阅读说明：本技术 非水性电解质溶液、可充电电池、微混合电池及电池系统 (Nonaqueous electrolyte solution, rechargeable battery, micro-hybrid battery, and battery system ) 是由 L·J·皮奈尔 C·坎皮恩 A·S·格兹泽 J·J·曹 于 2015-11-06 设计创作，主要内容包括：本发明公开了一种可充电电池、电池系统、微混合电池以及非水性电解质溶液。所述可充电电池包括含碳负极,能够进行嵌锂和脱锂；正极,包含锂过渡金属含氧阴离子盐电活性材料；分隔器；以及非水性电解质溶液,包含锂盐、双(三氟甲烷)磺酰胺锂、至少一种有机溶剂和1,3-丙烷磺内酯,其中,所述非水性电解质溶液不含γ-丁内酯,并且所述有机溶剂包含碳酸亚乙烯酯及亚硫酸乙烯酯。所述可充电电池在高温下维持长的充放电循环寿命并且在低温下也输出电力。(The invention discloses a rechargeable battery, a battery system, a micro-hybrid battery and a non-aqueous electrolyte solution. The rechargeable battery comprises a carbon-containing negative electrode capable of lithium intercalation and deintercalation; a positive electrode comprising a lithium transition metal oxyanion salt electroactive material; a separator; and a non-aqueous electrolyte solution comprising a lithium salt, lithium bis (trifluoromethane) sulfonamide, at least one organic solvent, and 1, 3-propane sultone, wherein the non-aqueous electrolyte solution does not contain gamma-butyrolactone, and the organic solvent comprises vinylene carbonate and vinyl sulfite. The rechargeable battery maintains a long charge-discharge cycle life at high temperatures and outputs power also at low temperatures.)

1. A rechargeable battery, comprising:

a carbon-containing negative electrode capable of lithium intercalation and deintercalation;

a positive electrode comprising a lithium transition metal oxyanion salt electroactive material;

a separator; and

a non-aqueous electrolyte solution comprising a lithium salt, lithium bis (trifluoromethane) sulfonamide, at least one organic solvent, and 1, 3-propane sultone, wherein the non-aqueous electrolyte solution does not contain gamma-butyrolactone, and the organic solvent comprises vinylene carbonate and vinyl sulfite.

2. The rechargeable battery according to claim 1,

the electrolyte solution contains 0.1 to 5 weight percent of ethylene sulfite, or

The electrolyte solution contains 1 to 3 weight percent of ethylene sulfite, or

The electrolyte solution contains 1 to 1.5 weight percent of ethylene sulfite.

3. The rechargeable battery according to claim 1,

the electrolyte solution contains 0.2 vol.% to 8 vol.% of the vinylene carbonate, or

The electrolyte solution contains 0.5 vol.% to 3 vol.% of the vinylene carbonate, or

The electrolyte solution contains 0.5 vol.% to 2 vol.% of the vinylene carbonate.

4. The rechargeable battery according to any one of claims 1 to 3,

the negative electrode comprises a carbon-containing material, and/or the negative electrode comprises non-graphitizable carbon, artificial graphite and/or natural graphite comprising a combination of a carbon-based material and silicon or silicon oxide.

5. The rechargeable battery according to claim 1, wherein the lithium transition metal oxyanion salt material is selected from the group consisting of:

formula Li_x(M′_1-aM″_a)_y(XO₄)_z、Li_x(M′_1-aM″_a)_y(OXO₄)_zOr Li_x(M′_1-aM″_a)_y(X₂O₇)_zHaving a temperature of at least 10 at 27 DEG C^-8(ii) S/cm, wherein M' is a first row transition metal, X is at least one of phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metals, 0.0001<a is less than or equal to 0.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that the sum of the products of the apparent valences of x, y (1-a) and M 'and the products of the apparent valences of ya and M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a);

formula (Li)_1-aM″_a)_xM′_y(XO₄)_z、(Li_1-aM″_a)_xM′_y(OXO₄)_zOr (Li)_1-aM″_a)_xM′_y(X₂O₇)_zHaving a temperature of at least 10 at 27 DEG C^-8(ii) conductivity of S/cm, wherein M' is a first row transition metal, X is phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum andat least one of tungsten, M' is one or more of metals of groups IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB, 0.0001<a is less than or equal to 0.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that (1-a) the sum of the products of x, ax and the apparent valence of M ", and the product of y and the apparent valence of M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a); and

formula (Li)_b-aM″_a)_xM′_y(XO₄)_z、(Li_b-aM″_a)_xM′_y(OXO₄)_zOr (Li)_b-aM″_a)_xM′_y(X₂O₇)_zHaving a temperature of at least about 10 at 27 ℃^-8(ii) S/cm, wherein M' is a first row transition metal, X is at least one of phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metals, 0.0001<a.ltoreq.0.1, a.ltoreq.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that the sum of (b-a) the products of x, ax and the apparent valency of M 'and the products of y and the apparent valency of M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a);

alternatively, the lithium transition metal oxyanion salt material is a lithium transition metal phosphate compound having a formula selected from the group consisting of:

(a)(Li_1-xZ_x)MPO₄wherein M is one or more of vanadium, chromium, manganese, iron, cobalt and nickel, Z is one or more of titanium, zirconium, niobium, aluminum, tantalum, tungsten or magnesium, and x is more than or equal to 0 and less than or equal to 0.05; and

(b)Li_1-xMPO₄wherein M is selected from the group consisting of vanadium, chromium, manganese, iron, cobalt and nickel, and x is greater than or equal to 0 and less than or equal to 1.

6. The rechargeable battery according to any one of claims 1 to 3,

the positive electrode has at least 5m²A specific surface area per gram, and

the positive electrode comprises an olivine-type lithium iron phosphate and preferably contains one or more other metals.

7. The rechargeable battery according to any one of claims 1 to 3,

the battery includes a Solid Electrolyte Interface (SEI) layer at the anode, and the SEI layer includes a reaction product resulting from a reaction of the carbon-containing negative electrode with vinyl sulfite; and

the area specific impedance at the anode is less than the impedance at the anode in a cell lacking the vinyl sulfite.

8. The rechargeable battery according to any one of claims 1 to 3,

the molar concentration of the lithium salt is between 0.5mol/l and 2.0mol/l, and

the lithium salt is selected from the group consisting of LiPF₆、LiClO₄、LiBF₄、LiCF₃SO₃、LiN(CF₃SO₂)₂、LiN(CF₃CF₂SO₂)₂、LiN(CF₃SO₂)(C₄F₉SO₂) And LiC (CF)₃SO₂)₃The group (2).

9. The rechargeable battery according to claim 1,

the organic solvent comprises at least one of: ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, gamma valerolactone, methyl acetate and methyl propionate, tetrahydrofuran, 2-methyltetrahydrofuran and tetrahydropyran, dimethoxyethane, dimethoxymethane, methylvinyl phosphate and ethylvinyl phosphate, trimethyl phosphate and triethyl phosphate, halides of the foregoing, vinyl carbonate (VEC) and fluoroethylene carbonate (FEC), poly (ethylene glycol) diacrylate, combinations of the foregoing, or

The electrolyte solution comprises a mixture of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and propylene carbonate.

10. A battery system comprising a plurality of rechargeable batteries, wherein,

the rechargeable battery comprising the rechargeable battery according to any one of claims 1 to 9,

the plurality of rechargeable batteries are configured to provide an operating voltage of 12-15 volts, an

The battery is capable of operating at a temperature of-30 ℃ to +70 ℃ without a battery management circuit.

11. A micro-hybrid battery, comprising:

a battery case;

a plurality of rechargeable batteries within the battery housing, the rechargeable batteries comprising the rechargeable battery of any one of claims 1-9; and

a disconnect switch for making and breaking conductive paths between the plurality of rechargeable batteries and external contacts, the batteries being capable of operating at a temperature of-30 ℃ to +70 ℃ without a battery management circuit.

12. The micro-hybrid battery of claim 11,

the battery has a capacity reduction of less than 10% after 300 charge-discharge cycles at 75 ℃, a charge rate of at least 1C, and a depth of discharge of 100%, or

The battery can provide at least 20% more current at-30 ℃ than a rechargeable battery lacking vinyl sulfite, or

The plurality of rechargeable batteries are configured to provide an operating voltage of 12-15 volts.

13. A non-aqueous electrolyte solution comprising:

a lithium salt,

lithium bis (trifluoromethane) sulfonamide,

at least one organic solvent, and

1, 3-propane sultone,

wherein the non-aqueous electrolyte solution does not contain gamma-butyrolactone, and the organic solvent contains vinylene carbonate and vinyl sulfite.

14. The non-aqueous electrolyte solution according to claim 13,

the electrolyte solution contains 0.1 wt% -5 wt%, 0.1 wt% -3 wt%, or 1 wt% -1.5 wt% of ethylene sulfite, and

the electrolyte solution contains 0.2 vol% -8 vol%, 0.5 vol% -3 vol%, or 0.5 vol% -2 vol% vinylene carbonate.

15. The non-aqueous electrolyte solution according to claim 13 or 14,

the solvent comprises at least one of: ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, gamma valerolactone, methyl acetate and methyl propionate, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, dimethoxyethane, dimethoxymethane, vinyl methyl phosphate and ethyl vinyl phosphate, trimethyl phosphate, triethyl phosphate, halides of the foregoing, vinylene carbonate (VEC) and fluoroethylene carbonate (FEC), poly (ethylene glycol) diacrylate, combinations of the foregoing, or

The electrolyte solution comprises a mixture of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and propylene carbonate.

Technical Field

The present invention relates to a non-aqueous electrolyte rechargeable battery having excellent low-temperature characteristics, long-term stability, and high energy density.

Background

Rechargeable batteries generate energy through electrochemical reactions. In conventional rechargeable batteries, the battery is designed to achieve optimal performance at or near room temperature. Either too high or too low a temperature can compromise the performance and/or life of the battery. To address performance issues at extreme temperatures, batteries may also incorporate heating and/or cooling systems, which adds volume, weight, complexity, and cost. In many cases, this limits the application of the battery in extreme temperature environments.

Disclosure of Invention

The inventors of the present invention have recognized that improved electrolyte formulations may be provided, thereby improving performance at extreme temperatures and reducing gassing (gassing). Some rechargeable batteries have been designed, which have a specific combination of anode, cathode and electrolyte compositions, thereby maintaining a long charge-discharge cycle life at high temperatures and outputting power also at low temperatures. For example, there is an electrolyte formulation having a first additive comprising a sulfonyl group for use in a rechargeable battery. The use of sulfonyl-containing additives in the electrolyte can provide a battery that maintains charge-discharge cycle life at high temperatures and still outputs power at low temperatures, thereby greatly reducing the need for a thermal management system.

In one embodiment, there is provided a rechargeable battery including: a carbon-containing negative electrode capable of lithium intercalation and deintercalation; a positive electrode comprising a lithium transition metal oxyanion salt electroactive material; a separator; and a non-aqueous electrolyte solution comprising a lithium salt andat least one organic solvent, wherein the non-aqueous electrolyte solution is free of gamma-butyrolactone, and the organic solvent comprises vinylene carbonate; and at least one sulfonyl-containing additive. In one example, the solution may additionally contain a co-salt, and the at least one additive may additionally comprise a second additive and/or an anti-gassing agent. In one example, there is provided a rechargeable battery containing a non-aqueous electrolyte solution comprising: lithium salt, LiPF₆0.6-2M; an organic solvent mixture comprising 35 vol.% ethylene carbonate, 5 vol.% propylene carbonate, 50 vol.% ethyl methyl carbonate and 10 vol.% diethyl carbonate; and at least one sulfonyl-containing additive, 0.1 to 5 wt.% of ethylene glycol sulfite and 0.2 to 8 wt.% of vinylene carbonate. The provided electrolyte formulations are capable of providing greater power at cold engine start compared to lead acid batteries and sustain longer charge-discharge cycle life at high temperatures.

The use of a sulfonyl-containing additive and vinylene carbonate in an organic electrolyte provides a stable, low impedance rechargeable lithium ion battery. The sulfonyl-containing additive may reduce impedance by reacting with the anode, thereby generating a stable Solid Electrolyte Interface (SEI) that is more ion-conductive than an electrolyte without the additive. In addition, vinylene carbonate may effectively passivate the carbon-based anode during first charge, so that the solubility of SEI is reduced, and thus, the decomposition of the sulfonyl additive may be reduced.

In another example, an electrolyte formulation is provided comprising: a first additive comprising a sulfonyl group, an anti-gassing agent, a second additive, and a salt system. In addition, the formulation comprises vinylene carbonate and a solvent system. The electrolyte formulation can be used in a variety of battery configurations, but is particularly beneficial for use in pouch-type battery configurations due to gassing reduction features.

The disclosed electrolyte formulations can reduce gassing over a wide temperature range during charge and discharge cycles. In addition, the ratio between the sulfonyl additive and vinylene carbonate can be controlled to maintain an improved SEI layer and thus to maintain improved charge-discharge cycle efficiency of the battery. As disclosed herein, optimized electrolyte formulations reduce/maintain impedance and provide improved power for cold start while also reducing gassing during high temperature charge-discharge cycles and/or storage.

As described herein, the first sulfonyl-containing additive may be 0.1-5 wt.% of the electrolyte formulation. The anti-gassing agent can be equal to or less than 2 wt.% of the electrolyte formulation and the second additive can be 0.1-5 wt.% of the electrolyte formulation. The additional additives may be selected so that both the vinylene carbonate loading is reduced and still good SEI growth is maintained. The salt system may comprise a lithium salt in combination with a co-salt, wherein the co-salt does not cause decomposition in the lewis acid form.

It is to be understood that the above summary is provided to facilitate a simplified description of the inventive concept and that the detailed description is provided for purposes of illustration. It is not intended to identify key or critical features of the claimed subject matter, the scope of which is defined solely by the claims that follow the detailed description. Additionally, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part hereof.

Drawings

Figure 1 shows the first capacity loss of the electrolyte formulation in LFP/graphite cells compared to the control electrolyte (LPF cathode, graphite anode, mini-cell ICL and n-ICL).

Figure 2 shows the first capacity loss of the electrolyte formulation in a cell with an NCM cathode and a graphite anode (NCM cathode, graphite anode, mini-cell ICL) compared to a control electrolyte.

Fig. 3 shows the impedance of the electrolyte formulation in an LFP/graphite cell (LFP cathode, graphite anode, mini-cell impedance) compared to a control electrolyte.

Figure 4 shows the impedance of the electrolyte formulation in the NCM/graphite cell (NCM cathode, graphite anode, small cell ACR impedance) compared to the control electrolyte.

Figure 5A shows the mixed pulse power performance (HPPC) at 23 ℃ under 1 second pulse power for the electrolyte formulation in LFP/graphite cells compared to the control electrolyte (LFP cathode, graphite anode, mini-cell HPPC, +23 degrees celsius (1 second discharge)).

Figure 5B shows the electrolyte formulation in LFP/graphite cells at 10 second pulsed power performance (HPPC) at 23 ℃ (LFP cathode, graphite anode, mini-cell HPPC, +23 degrees celsius (10 second discharge)) compared to control electrolytes.

Figure 6A shows the mixed pulse power performance (HPPC) at-20 ℃ under 1 second pulse power for the electrolyte formulation in LFP/graphite cells compared to the control electrolyte (LFP cathode, graphite anode, mini-cell HPPC, -20 degrees celsius (1 second discharge)).

Figure 6B shows the mixed pulse power performance (HPPC) at-20 ℃ under 10 seconds pulsed power for the electrolyte formulation in LFP/graphite cells compared to the control electrolyte (LFP cathode, graphite anode, mini-cell HPPC, -20 degrees celsius (10 seconds discharge)).

Figure 7 shows the power provided by the electrolyte formulation in LFP/graphite cells at-30 ℃ in cold start test (LFP cathode, graphite anode, small cell 70% SOC, cold start (2V-CV), -30 ℃ c) compared to control electrolytes.

Figure 8 shows the power provided by an NCM/graphite cell with the electrolyte formulation in a cold start test at-30 ℃ (NCM cathode, graphite anode, mini-cell cold start power at-30 ℃) compared to a control electrolyte.

Figure 9 shows the high temperature charge-discharge cycle life test results (1C charge, 4C discharge at 60 degrees celsius for NCM cathode, graphite anode, mini-cell) for NCM/graphite cells with the electrolyte formulation compared to the control electrolyte.

Fig. 10 shows the volume change at 60 ℃ storage conditions for LFP/graphite cells with the electrolyte formulation compared to control electrolytes (volume change time 1: one week for LFP/graphite, small cells after storage at 60 ℃ time 2: two weeks for storage again).

Fig. 11 shows an exemplary pouch-type battery configuration used in conjunction with the electrolyte formulation.

Fig. 12 is a schematic diagram of an exemplary micro-hybrid battery according to one or more embodiments (1230: casing, 1250: terminal bus, 1240: integrated BMS/FET, 1260: lower case, 1210 prism module, 1270: 20Ah prism battery).

Fig. 13 is a graph of an anode half-cell formation curve with ES additive only in the electrolyte, according to one or more embodiments.

Fig. 14 is a graph of single-use formation curves for two secondary batteries, one containing only an ES additive in the electrolyte and the other containing ES and VC in the electrolyte, according to one or more embodiments.

Fig. 15A and 15B are two graphs of the cold start current capability of three different 60Ah (fig. 15A) and 80Ah (fig. 15B) capacity batteries, which are a lead-acid AG1V1 battery, a control lithium metal phosphate battery, and a lithium metal phosphate battery with a modified electrolyte composition (cold start at 7V for 10 seconds 100%).

Fig. 16A and 16B are comparative plots of capacity loss at 55 ℃ for two 6Ah (fig. 16A) and 20Ah (fig. 16B) capacity batteries, a control lithium metal phosphate battery and a lithium metal phosphate battery with a modified electrolyte composition (fig. 16A: 6Ah prism, 55 degrees celsius storage, 100% SOC; fig. 16B: 20Ah prism, 55 degrees celsius storage, 100% SOC), respectively, according to one or more embodiments.

Fig. 17A and 17B are comparative plots of power loss at 55 ℃ for two 6Ah (fig. 17A) and 20Ah (fig. 17B) capacity batteries, a control lithium metal phosphate battery and a lithium metal phosphate battery with a modified electrolyte composition (fig. 17A: 6Ah prism, 55 degrees celsius storage, 100% SOC; fig. 17B: 20Ah prism, 55 degrees celsius storage, 100% SOC), respectively, according to one or more embodiments.

Fig. 18A and 18B are graphs comparing capacity loss at 45 ℃ for 5000 (fig. 18A) and 1800 (fig. 18B) charge-discharge cycles for lithium metal phosphate batteries and related competitive batteries with modified electrolyte compositions (fig. 18A: 1.5C-10C, 100% DOD at 45 ℃ charge-discharge cycles; fig. 18B: 1C-1C, 100% DOD at 45 ℃ charge-discharge cycles).

Fig. 19A and 19B are comparative plots of capacity loss for lithium metal phosphate cells and related competitive cells with modified electrolyte compositions at 60 ℃ (fig. 19A) and 75 ℃ (fig. 19B) (fig. 19A: 1C-4C, 100% DOD at 60 degrees celsius charge-discharge cycles; fig. 19B: 1C-4C, 100% DOD at 75 degrees celsius charge-discharge cycles).

Fig. 20 is a graph of relative DC resistance change versus number of charge and discharge cycles for two PHEV 20Ah batteries, a control lithium metal phosphate battery and a lithium metal phosphate battery with a modified electrolyte composition (charge and discharge cycles at 60 degrees celsius versus DCR vs. number of charge and discharge cycles 1C, 4C), respectively, according to one or more embodiments.

Detailed Description

Aspects of the present invention will now be described, by way of example, with reference to the above-described illustrated embodiments. Components, process steps, and other elements that may be substantially the same in one or more embodiments are listed close together and are described with the intent to avoid repetition. It should be noted, however, that closely listed elements may also differ to some extent.

The invention provides an optimized electrolyte formulation comprising: a first additive comprising a sulfonyl group, an anti-gassing agent, a second additive for reducing impedance, and a salt system. The optimized electrolyte formulation achieved an unexpected improvement in first-time capacity loss compared to the control electrolyte formulation, as shown in fig. 1 and 2. In addition, the optimized electrolyte formulations provided similar/or reduced direct current and alternating current resistances (DCR, ACR) as compared to the control electrolyte formulations, as shown in fig. 3, 4, 5A, 5B, 6A, and 6B. The optimized electrolyte formulation further exhibited improved cold start power as shown in fig. 7 and 8, and an unexpected improvement over charge-discharge cycling over a wider temperature range as shown in fig. 9. In addition, this particular electrolyte formulation has the unexpected result of reducing the impedance while simultaneously reducing gassing, as shown in fig. 10. The lower gassing characteristics of the electrolyte formulation enable the electrolyte formulation to be used in a variety of battery configurations, particularly the pouch-type battery configuration shown in fig. 11.

As described above, the electrolyte formulation enables low gassing at high temperatures and low impedance at very low temperatures and provides good SEI growth. Table 1 shows the range of additives and salt systems for example electrolyte formulations according to the present invention.

Table 1: electrolyte formulation

As shown in the table above, the electrolyte formulation can be viewed as having an additive system and a salt system. Each component contained in the additive system was less than 5 wt.%. The disclosed additive system comprises a first additive comprising a sulfonyl group, vinylene carbonate, an anti-gassing additive, and a second additive. The combination of the first sulfonyl-containing additive, vinylene carbonate, anti-gassing additive, and second additive reduces the resistance and enhances the SEI layer.

In addition, the anti-gassing additive in the disclosed additive system reduces gas generation that might otherwise occur as a result of the reaction of one or more other additives (e.g., the sulfonyl-containing first additive). The electrolyte additive system is specifically designed to control gas generation and mitigate increases in resistance due to certain additives, such as anti-gassing additives and SEI-forming additives, by providing a formulation that allows for a lower weight percentage of sulfonyl-containing additives, a lower weight percentage of SEI-forming additives, to be used in combination with the salt system.

Due to the inclusion of the co-salt,the disclosed salt system enables the use of lower amounts of LiPF₆. The co-salt is selected from materials that do not generate lewis acid species upon decomposition. The unexpected effect of including the co-salt is due to the fact that from LiPF₆The concentration of the lewis acid product formed by the decomposition is relatively low, so a relatively low weight percentage of the at least one sulfonyl-containing additive may be used. The unexpected benefit of a lower weight percentage of the at least one sulfonyl-containing additive is also that lower amounts of gassing inhibitor can be used to reduce the high impedance problems that typically occur with gassing inhibitors. This unique formulation results in a low gassing and reduced impedance battery as opposed to the use of anti-gassing additives and sulfonyl-containing additives.

In use, the electrolyte formulation provides an improved battery. For example, a rechargeable battery may include an anode (also referred to as a negative electrode), a cathode (also referred to as a positive electrode), a separator, and a non-aqueous electrolyte solution (such as an electrolyte of the present invention). Rechargeable batteries comprising the cells described herein have low gassing, maintain long charge-discharge cycle life over a wide temperature range, reduce impedance, and improve power at cold start. In another example, the electrolyte formulation may be used in a lithium ion battery.

As described above, the electrolyte formulation is a non-aqueous electrolyte solution and may include an additive system and a salt system. The additive system may include a first additive comprising a sulfonyl group, vinylene carbonate, an anti-gassing additive, and a second additive. In one example, the salt system may comprise LiPF₆And co-salts. Additionally, the solution comprises a solvent system.

The at least one sulfonyl-containing first additive may reduce the vinylene carbonate loading while still maintaining good SEI growth. For example, the first sulfonyl-containing additive may be represented by the following formula (1):

R₁—A—R₂ (1)

wherein R is₁And R₂Each independently being optionally substituted by aryl or halogen atomsSubstituted alkyl; an aryl group which may be substituted with an alkyl group or a halogen atom; or R₁And R₂May form a cyclic structure together with-a-, the cyclic structure may further contain an unsaturated bond, wherein "a" represents a formula selected from the group consisting of:

and

R₁and R₂There may be mentioned alkyl groups having 1 to 4 carbon atoms, and specifically methyl, ethyl, propyl, isopropyl and butyl groups. Examples of the aromatic group which can substitute for the alkyl group include phenyl, naphthyl and anthracenyl, of which phenyl is preferable. Examples of the halogen atom which can substitute for the alkyl group include a fluorine atom, a chlorine atom and a bromine atom. The alkyl group may be substituted with a plurality of such substituents, and simultaneous substitution with an aryl group and a halogen atom group is also possible.

From R₁And R₂The cyclic structure formed by bonding to each other and together with- -A- -is a four-membered ring or larger, and may contain a double bond or a triple bond. From R₁And R₂Examples of the groups bonded to each other include- -CH₂--、--CH₂CH₂CH₂--、--CH₂CH₂CH₂CH₂--、--CH₂CH₂CH₂CH₂CH₂--、--CH＝CH--、--CH＝CHCH₂--、--CH₂CH＝CHCH₂- - -and- -CH₂CH₂C≡CCH₂CH₂- -. One or more hydrogen atoms in these groups may be substituted with an alkyl group, a halogen atom, an aryl group, or the like.

In one or more embodiments, the electrolyte solution contains 0.1 wt.% to 5 wt.% of the compound represented by formula (1).

In one or more embodiments, the electrolyte solution contains 1 wt.% to 3 wt.% of the compound represented by formula (1). In another embodiment, the electrolyte solution contains 0.1 wt.% to 3 wt.% of the compound represented by formula (1).

In one or more embodiments, the electrolyte solution contains 1 wt.% to 1.5 wt.% of the compound represented by formula (1).

In one or more embodiments, the electrolyte solution contains 0.2 vol.% to 8 vol.% vinylene carbonate.

In one or more embodiments, the electrolyte solution contains 0.5 vol.% to 3 vol.% vinylene carbonate.

In one or more embodiments, the electrolyte solution contains 0.5 vol.% to 2 vol.% vinylene carbonate.

In one or more embodiments, the compound represented by formula (1) is vinyl sulfite.

In one or more embodiments, the electrolyte solution further comprises an aprotic solvent.

In one or more embodiments, the negative electrode comprises non-graphitizable carbon, artificial graphite, or natural graphite combinations of carbon-based materials with silicon or silicon oxides.

Specific examples of the molecule having "a" represented by the formula (2) include: linear sulfites such as dimethyl sulfite, diethyl sulfite, methylethyl sulfite, methylpropyl sulfite, ethylpropyl sulfite, diphenyl sulfite, methylphenyl sulfite, ethyl sulfite, dibenzyl sulfite, benzyl methyl sulfite, and benzyl ethyl sulfite; cyclic sulfite esters such as vinyl sulfite, propylene sulfite, butylene sulfite, vinylene sulfite, phenyl vinyl sulfite, 1-methyl-2-phenyl ethylene sulfite, and 1-ethyl-2-phenyl ethylene sulfite; and also the halides of such linear and cyclic sulfites.

Specific examples of the molecule having "a" represented by the formula (3) include: linear sulfones such as dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, methyl propyl sulfone, ethyl propyl sulfone, diphenyl sulfone, methyl phenyl sulfone, ethyl phenyl sulfone, dibenzyl sulfone, benzyl methyl sulfone, and benzyl ethyl sulfone; cyclic sulfones such as sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-ethylsulfolane, 3-ethylsulfolane, 2, 4-dimethylsulfolane, sulfolene, 3-methylsulfolane, 2-phenylsulfolane and 3-phenylsulfolane; and halides of such linear and cyclic sulfones.

Specific examples of the molecule having "A" shown in the formula (4) include: linear sulfonates such as methyl methanesulfonate, ethyl methanesulfonate, propyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, propyl ethanesulfonate, methyl benzenesulfonate, ethyl benzenesulfonate, propyl benzenesulfonate, phenyl methanesulfonate, phenyl ethanesulfonate, phenyl propanesulfonate, methyl benzylsulfonate, ethyl benzylsulfonate, propyl benzylsulfonate, benzyl methanesulfonate, benzyl ethanesulfonate, and benzyl propanesulfonate; cyclic sulfonic acid esters such as 1, 3-propane sultone, 1, 4-butane sultone, 3-phenyl-1, 3-propane sultone, and 4-phenyl-1, 4-butane sultone; and halides of such linear and cyclic sulfonates.

Specific examples of the molecule having "A" shown in the formula (5) include: linear sulfates such as dimethyl sulfate, diethyl sulfate, ethylmethyl sulfate, methylpropyl sulfate, ethylpropyl sulfate, methylphenyl sulfate, ethylphenyl sulfate, phenylpropyl sulfate, benzylmethyl sulfate, and benzylethyl sulfate; cyclic sulfates such as ethylene glycol cyclic sulfate, 1, 2-propylene glycol cyclic sulfate, 1, 3-propylene glycol cyclic sulfate, 1, 2-butylene glycol cyclic sulfate, 1, 3-butylene glycol cyclic sulfate, 2, 3-butylene glycol cyclic sulfate, phenyl ethylene glycol cyclic sulfate, methyl phenyl ethylene glycol cyclic sulfate, and ethyl phenyl ethylene glycol cyclic sulfate; and the halides of such linear and cyclic sulfates.

In the electrolyte formulation, the molecules represented by formula (1) may be used alone, or two or more of such molecules may be used in combination.

Examples of the first sulfonyl group-containing additive represented by formula (1) include vinyl sulfite, dimethyl sulfite, sulfolane, sulfolene, and sultone.

The amount of the first additive represented by formula (1) contained in the organic solvent of the non-aqueous electrolyte solution is preferably in the range of 0.05 to 100 vol.%, 0.05 to 60 vol.%, 0.1 to 15 vol.%, or 0.5 to 2 vol.%. Alternatively, the first additive accounts for 0.1-5 wt.%, 0.1-3 wt.%, or 0.1-1 wt.% of the electrolyte formulation. Some of the first additives represented by formula (1) are solid at room temperature, and such molecules are preferably used in an amount equal to or lower than the saturated solubility of the organic solvent used, more preferably in an amount of 60 wt.% or less, more preferably in an amount of 30 wt.% or less, of the saturated solubility. Thus, the additive remains dissolved and in solution in the organic solvent over the expected temperature range of use, such as between-30 ℃ and +70 ℃.

Vinylene carbonate is effective in passivating the carbon-based anode during first charge, and thus can reduce decomposition of the additive by making the SEI less soluble. The vinylene carbonate may be added in an amount of 0.1-5 wt.% of the electrolyte formulation. The vinylene carbonate amount can be adjusted such that the ratio (VC: -A- -) between the vinylene carbonate and the sulfonyl-containing additive is optimized to reduce the vinylene carbonate loading while still maintaining a good SEI layer to achieve improved battery charge-discharge cycle efficiency. In one example, the ratio between VC: -A-may be 1: 1. In another example, the ratio between VC: -A-may be 2: 1.5. In another example, the ratio between VC: -A-may be 2:1.

Additionally, in the additive system, the anti-gassing agent can be added to the electrolyte to reduce gas formation during cell use. In some examples, the anti-gassing agent can function by deactivating catalytic sites in the cathode active material. While anti-gassing agents generally increase the impedance of the battery, the presently disclosed electrolyte formulations provide improved and/or maintained impedance levels. In particular, the electrolyte formulation in the present invention can reduce the loading of anti-gassing agents, plus the specific combination of additives and salt systems, further reducing the cell impedance.

In some example embodiments, the anti-gassing agent may be less than 2.0 wt.%, less than 1.5 wt.%, or less than 1.0 wt.% in the electrolyte formulation. For example, the anti-gassing agent may be selected from at least one of the following: 1,5,2,4-dioxadithiane-2,2,4,4-tetraoxide (1,5,2, 4-dioxaadithane-2, 2,4,4-tetraoxide, MMDS), 1,3- (1-propenyl) sultone (PrS), or 1, 3-propane sultone. In another example, the anti-gassing agent can be at least one or more of 1,5,2,4-dioxadithiane-2,2,4,4-tetraoxide (MMDS), 1,3- (1-propenyl) sultone (PrS), or 1, 3-propane sultone.

In other examples, other anti-gassing agents may be selected that reduce gas formation during use of the cell. In one example, 1, 3-propane sultone may be used. The anti-gassing agent can be different from the at least one first sulfonyl-containing additive and can be used in combination with the sulfonyl-containing additive. It may be noted that the anti-gassing agent and the sulfonyl-containing additive may perform different functions in the electrolyte.

Additionally, as described above, the additive system may comprise a second additive. The second additive can be used to reduce the vinylene carbonate loading while still maintaining good SEI growth to achieve improved battery charge-discharge cycle efficiency. The second additive may be less than 5 wt.% of the electrolyte formulation. For example, the second additive may be in the range of 0.1 to 5.0 wt.%. In one embodiment, more than one second additive may be used to further reduce impedance while maintaining gas suppression and good charge-discharge cycle life over a wide temperature range. In one example, fluoroethylene carbonate (FEC) may be included as the second additive.

In addition to the additive system, the electrolyte formulation comprises a salt system. The salt system comprises a lithium salt and a co-salt. In particular, the salt system for the non-aqueous electrolyte solution comprises a lithium salt in combination with a co-salt, wherein the co-salt does not produce a lewis acid product upon decomposition. By adding a lithium salt such as LiPF₆And without LiPF₆The combination of co-salt phases of the disadvantages, the salt system chosen, retains the advantages of the lithium salt. By choosing to combine co-salts with lithium salts, the problem of strong lewis acids, such as by LiPF, can be solved₆Is generated by the decomposition mechanism of₅And OPF₃。

The lithium salt may be selected to have a reactivity with LiPF₆Similar advantageous properties. For example, the lithium salt may be selected from the following: LiPF₆、LiClO₄、LiBF₄、LiCF₃SO₃、LiN(CF₃SO₂)₂、LiN(CF₃CF₂SO₂)₂、LiN(CFSO₂)(C₄F₉SO₂) And LiC (CF)₃SO₂)₂。

The co-salt may be selected from salts having at least one or more of the following properties: salts that do not readily decompose; salts of lewis acid species are not produced upon decomposition (thus further reducing gassing via electrolyte decomposition); salts that are resistant to protic solvents or protic impurities in the solvent system; less salt is generated by self gassing; and salts having good conductivity at low temperatures and not increasing the cell impedance, especially at low temperatures. In addition, the selected co-salts may have one or more of the following other properties: high solubility in carbon-containing solvents, good electrical conductivity over a range of temperatures, and no increase in resistance. For example, the co-salt may be selected to be one that does not form or produce lewis acid type decomposition products during decomposition. In one example, the co-salt may be selected to be one that does not produce or generate lewis acid decomposition products during pyrolysis.

By way of example, and not limitation, theThe salt may include: for example, imide salts, triflate salts, organoborates, and fluorinated analogs thereof. Examples of the imide salt may include lithium bis (trifluoromethane) sulfonamide (LiTFSI) and lithium bis (pentafluoroethane sulfonyl) imide (LiBETI). Examples of the trifluoromethanesulfonate may include lithium trifluoromethanesulfonate (LiSO)₃CF₃). Examples of the organoborates may include lithium bis (oxalato) borate (LiBOB) and fluorinated analogs thereof such as lithium difluoro (oxalato) borate (LiFOB).

In one embodiment, the salt system may include LiPF₆And lithium salt of sulfonamide. As another non-limiting specific example, the salt system may include LiPF₆And LiTFSI.

The salt system may comprise up to 2.0M, or 0.5M to 1.5M, or 0.5M to 1.0M of a lithium salt. In one or more embodiments, the lithium salt is between 0.5M and 2M. The co-salt may be present as part of the overall molar loading of the salt in the salt system. The co-salt may be up to 0.25M or 0.05M to 0.15M.

In addition to the additive system and salt system, an organic solvent system may be included in the electrolyte formulation. Examples of the organic solvent include: cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate; cyclic esters such as gamma valerolactone; chain esters such as methyl acetate and methyl propionate; cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, and tetrahydropyran; chain ethers such as dimethoxyethane and dimethoxymethane; cyclic phosphate esters such as methyl vinyl phosphate and ethyl vinyl phosphate; linear phosphates such as trimethyl phosphate and triethyl phosphate; halides of the above; sulfur-containing organic solvents other than the substance represented by formula (1), and vinyl carbonate (VEC) and fluoroethylene carbonate (FEC), poly (ethylene glycol) diacrylate. These organic solvents may be used alone, or two or more of these solvents may be used in combination.

In one or more embodiments, the electrolyte solution comprises a mixture of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, and diethyl carbonate.

In one illustrative example, the electrolyte formulation may comprise: containing LiPF₆And a co-salt of LiTFSI; a solvent system comprising Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC) and Propylene Carbonate (PC); ethylene Sulfite (ES) as a sulfonyl group-containing additive; vinylene Carbonate (VC) and fluoroethylene carbonate (FEC) as additional additives, and 1, 3-Propane Sultone (PS) as an anti-gassing agent.

The rechargeable battery contains a positive electrode. In some examples, the positive electrochemically active material may be a lithium metal oxide. For example, LiCoO, lithium cobalt oxide₂Can be used as the electrochemically active material of the positive electrode. In some other examples, the positive electrochemically active material may be a lithium transition metal oxyanion salt material selected from the following groups:

(a) formula Li_x(M′_1-aM″_a)_y(XO₄)_z、Li_x(M′_1-aM″_a)_y(OXO₄)_zOr Li_x(M′_1-aM″_a)_y(X₂O₇)_zHaving a temperature of at least about 10 at 27 ℃^-8(ii) electrical conductivity of S/cm, wherein M 'is a first row transition metal, X is at least one of phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M' is one or more of group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metals, 0.0001<a is less than or equal to 0.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that the sum of the products of the apparent valences of x, y (1-a) and M 'and the products of the apparent valences of ya and M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a);

(b) formula (Li)_1-aM″_a)_xM′_y(XO₄)_z、(Li_1-aM″_a)_xM′_y(OXO₄)_zOr (Li)_1-aM″_a)_xM′_y(X₂O₇)_zHaving a temperature of at least about 10 at 27 ℃^-8(ii) S/cm, wherein M' is a first row transition metal, X is at least one of phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metals, 0.0001<a is less than or equal to 0.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that (1-a) the sum of the products of x, ax and the apparent valence of M ", and the product of y and the apparent valence of M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a);

(c) formula (Li)_b-aM″_a)_xM′_y(XO₄)_z、(Li_b-aM″_a)_xM′_y(OXO₄)_zOr (Li)_b-aM″_a)_xM′_y(X₂O₇)_zHaving a temperature of at least about 10 at 27 ℃^-8(ii) S/cm, wherein M' is a first row transition metal, X is at least one of phosphorus, sulfur, arsenic, boron, aluminum, silicon, vanadium, molybdenum and tungsten, M "is one or more of group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB and VIB metals, 0.0001<a.ltoreq.0.1, a.ltoreq.1, the values of x, y and z are each greater than 0 and the values of x, y and z are such that the sum of (b-a) the products of x, ax and the apparent valency of M 'and the products of y and the apparent valency of M' is equal to z and XO₄、X₂O₇Or OXO₄The product of the apparent valencies of (a).

In one or more embodiments, the lithium transition metal oxyanion salt material is a lithium transition metal phosphate compound having a formula selected from the group consisting of:

(a)(Li_1-xZ_x)MPO₄wherein M is one or more of vanadium, chromium, manganese, iron, cobalt and nickel, Z is one or more of titanium, zirconium, niobium, aluminum, tantalum, tungsten or magnesium, and x is 0-0.05; and

(b)Li_1-xMPO₄wherein M is selected from the group consisting of vanadium, chromium, manganese, iron, cobalt and nickel, and x is 0-1.

In other examples, the cathode active material is: having the formula (Li)_1-xZ_x)MPO₄Wherein M is one or more of vanadium, chromium, manganese, iron, cobalt and nickel, Z is one or more of titanium, zirconium, niobium, aluminum, tantalum, tungsten or magnesium, and x is 0-0.05; or Li_1-xMPO₄Wherein M is one selected from vanadium, chromium, manganese, iron, cobalt and nickel, and x is more than or equal to 0 and less than or equal to 1.

In yet another example, the positive electrochemically active material is a lithium metal phosphate, such as lithium iron phosphate. The electrochemically active material of the positive electrode can be present in the form of a powder or granules having a specific surface area of more than 5m²/g、10m²Per g, or greater than 15m²Per g, or more than 20m²In terms of/g, or even greater than 30m²/g。

For example, the cathode may comprise lithium metal phosphate. In one example, the lithium metal phosphate can be lithium iron phosphate, LiFePO₄. Further, LiFePO₄Can have an olivine structure and can be made in the form of fine particles having a large specific surface area, and these fine particles are unusually stable in the delithiated form even at high temperatures and in the presence of oxidizable organic solvents (e.g., electrolytes), thereby realizing safer Li-ion batteries with extremely high charge and discharge rates, and also exhibit excellent retention during their lithium intercalation and delithiation in hundreds or even thousands of high rate charge and discharge cycles.

The rechargeable battery includes a negative electrode capable of lithium intercalation and deintercalation. For example, the anode may comprise graphite or a silicon/graphite electrochemically active material. In one example, when a graphite carbonaceous material is used, artificial graphite processed by annealing soft pitch (graphitizable pitch) derived from various sources, purified natural graphite, or products obtained by subjecting the above graphite to various surface processing such as pitch may be used.

In one or more embodiments, the battery includes a Solid Electrolyte Interface (SEI) layer at the anode, and the SEI layer includes a reaction product obtained by reacting a carbon-containing negative electrode with an additive represented by formula (1).

In one or more embodiments, the area specific impedance (area specific impedance) at the anode is less than the impedance at the anode in a cell lacking the additive represented by formula (1).

There is no limitation on the method of manufacturing the anode or the cathode using the above active material. In one example, an electroactive material is mixed with a binder, a conductive material, a solvent, and the like to prepare a slurry, and then the slurry is coated on a substrate of a current collector, followed by drying to make an electrode. In addition, such electrode materials may be subjected to a roll forming or compression molding process to be prepared in a sheet or pellet form, respectively.

The type of binder used for manufacturing the electrode is not particularly limited as long as it can be stable with respect to the solvent and electrolyte solution used in the manufacture of the electrode. Examples of such binders include: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aramid, and cellulose; rubber polymers such as styrene-butadiene rubber, isoprene rubber, butadiene rubber, and ethylene propylene rubber; thermoplastic elastomeric polymers such as styrene-butadiene-styrene block copolymers and hydrogenated products thereof, styrene-ethylene-styrene block copolymers and hydrogenated products thereof; elastic resin polymers such as syndiotactic 1, 2-polybutadiene, ethylene-vinyl acetate copolymers and propylene- α -olefin (having 2 to 12 carbon atoms) copolymers; and fluorocarbon polymers such as polyvinylidene fluoride, polytetrafluoroethylene, and polytetrafluoroethylene-ethylene copolymers.

For the binder, polymer formulations having alkali metal ion (in particular lithium ion) conductivity may also be used. For such ion-conducting polymer formulations, complex systems of polymeric compounds in combination with lithium or alkali metal salts may be used.

The anode material and the binder may be mixed in various ways. For example, the particles of the anode material and the particles of the binder may be mixed, or the particles of the anode material may be bound with a fibrous binder to generate a mixture, or a layer of the binder may be deposited on the surface of the particles of the anode material. In one example, the mixing ratio of the binder to the anode material may be 0.1 to 30 wt.% of the anode material. In another example, the mixing ratio of the binder to the anode material may be 0.5 to 10 wt.% of the anode material. The addition of the binder in an amount exceeding 30 wt.% may increase the internal resistance of the electrode, while an amount below 0.1 wt.% may weaken the adhesive strength between the current collector and the anode material.

When the anode material is mixed with the binder, a conductive material may also be mixed therein. The conductive material may be a metal or a nonmetal, since the type of conductive material used is not limited. For example, the metallic conductive material may be composed of a metallic element such as Cu or Ni. In another example, the non-metallic conductive material may be a carbon material such as graphite, carbon black, acetylene black, and Ketjen black (Ketjen black). The average particle diameter of the conductive material may be 1 μm or less.

In one example, the mixing ratio of the conductive material may be 0.1 to 30 wt.% of the negative electrode material. In another example, the mixing ratio of the conductive material may be 0.5 to 15 wt.% of the negative electrode material. A mixing ratio of the conductive additive of more than 0.1 wt.% may provide a sufficiently formed conductive path between the conductive materials within the electrode.

The above mixture containing at least the anode material and the binder may be coated on a current collector foil. The application of the mixture to the current collector may be accomplished by means well known to those skilled in the art. For example, when the mixture is a slurry, the slurry may be applied to the current collector by roll coating. In another example, when the mixture contains a solvent, the solvent may be dried to remove the solvent, so that an electrode may be manufactured.

Positive electrodes containing positive electroactive materials having electrode specific surface areas of greater than 5m as measured using the nitrogen adsorption Brunauer-Emmet-Teller (BET) method after densification or calendering step²(ii) in terms of/g. The positive electrode may have less than on each side of the current collectorA thickness of 125 μm, for example, between about 50 μm and 125 μm, or between about 80 μm and 100 μm, and a volume porosity of about 40-70 vol.%. The loading of the active material is typically about 10-20mg/cm²And is usually about 11 to 15mg/cm²。

The negative active material may be composed of a powder or particles having a specific surface area greater than about 2m as measured using the nitrogen adsorption Brunauer-Emmet-Teller (BET) method²Per g, or 4m²In terms of/g, or even about 6m²(ii) in terms of/g. The anode may have a thickness of less than 75 μm, for example, between about 20 to 65 μm, or between about 40 to 55 μm, and a volume porosity of between about 20 to 40 vol.% on both sides of the current collector. The loading of the active material may typically be in the range of about 5-20mg/cm²Or about 4-5mg/cm²。

It is to be noted that there is no particular limitation on the manufacturing process of the positive electrode, and a similar method may be used for the negative electrode as described above.

It is to be noted that there is no particular limitation on the raw material and form of the separator used in the battery of the present invention. The separator serves to separate the positive electrode from the negative electrode to avoid physical contact of the positive electrode with the negative electrode. In one example, the separator may have high ion permeability and low electrical resistance. The material for the separator may preferably be selected from those having good stability to the electrolyte solution and good liquid retention characteristics. For example, a non-woven fabric or a porous film made of polyolefin such as polyethylene and polypropylene may be used as the separator, into which the electrolyte solution permeates.

The method of manufacturing a nonaqueous electrolyte solution battery using such a nonaqueous electrolyte solution, negative electrode, positive electrode, outer container, and separator is not particularly limited, and may be selected from commonly used methods. In addition to such a nonaqueous electrolyte solution, a negative electrode, a positive electrode, a casing or an outer casing material, and a separator, the nonaqueous electrolyte battery of the present invention may further include a gasket, a sealing plate, and a battery case. In one example, the non-aqueous electrolyte solution battery of the present invention may be configured as a pouch (pouch) due to low electrolyte gassing over a wide temperature range.

The batteries described herein exhibit advantageous properties over a wide temperature range over which battery operation can be expected. For example, the battery can be operated between-30 ℃ and +70 ℃. In addition, batteries with the disclosed electrolyte formulations have less gassing and lower impedance. The low impedance of the battery is important to improve performance at low temperatures and to extend the useful life of the battery. The above-described advantageous and unexpected properties may be achieved by an electrolyte formulation comprising an organic solvent, a first additive comprising a sulfonyl group, vinylene carbonate, an anti-gassing agent, a second additive to mitigate vinylene carbonate loading, and a salt system in which a lithium salt is combined with a co-salt, wherein the co-salt does not produce lewis acid decomposition products. The amount of vinylene carbonate can be adjusted such that the ratio between the sulfonyl-containing additive and the vinylene carbonate is optimized to reduce vinylene carbonate loading while still maintaining a good SEI layer, thereby improving battery charge-discharge cycle efficiency.

In general, the thicker the electrode layer (the higher the active material loading), the greater the overall cell capacity. However, thicker layers also increase electrode resistance. Contrary to conventional practice, a high capacity thick layer may be used in a low impedance (high rate) cell, according to one or more embodiments. The use of high specific surface area active materials while maintaining a sufficiently large pore volume can provide the desired capacity without increasing the impedance to unacceptably high levels.

In the context of battery containers, low gassing electrolyte formulations can be used in pouches as well as other configurations.

The choice of organic solvent in the electrolyte is also important to reduce the impedance. In some embodiments, the electrolyte is advantageously free of γ -butyrolactone, as γ -butyrolactone undergoes reductive oxidation at the negative electrode upon charging of the cell (see Petibon et al, Journal of the Electrochemical Society,160(1) A117-A124 (2013)). The resulting decomposition products may cause clogging of the separator. This blockage then increases the surface resistance of the negative electrode, thus increasing the impedance of the anode, resulting in significant capacity loss with charge and discharge cycles.

Furthermore, the use of additives as shown in formula (1) in addition to Vinylene Carbonate (VC) in the non-aqueous organic electrolyte also contributes to a stable low impedance lithium ion battery. Without being bound by any particular theory, it appears that the additive lowers the impedance by reacting with the anode to form an SEI that is more ionically conductive than when an electrolyte without the additive is used. In addition, VC can more effectively passivate the carbon-based anode upon first charge. VC prevents the additive from decomposing by making the SEI less soluble.

SEI results from the thermodynamic instability of graphite-based anodes in organic electrolytes. The graphite reacts with the electrolyte when the battery is first charged, i.e. when so-called formed (formation). This forms a porous passivation layer, also known as a Solid Electrolyte Interface (SEI), which protects the anode from further corrosion, moderates the charge rate and limits the current. The reaction consumes little lithium. At high temperatures, or when the battery is depleted to zero charge ("deep charge-discharge cycling"), the SEI may partially dissolve into the electrolyte. At high temperatures, the electrolyte also decomposes and side reactions accelerate, possibly leading to thermal depletion. As the temperature is lowered, another protective layer will form, but will consume more lithium, resulting in higher capacity loss. Thus, one advantage of the batteries described herein is the stability of the SEI at high temperatures, which is important to extend the battery life. In addition, the batteries described herein can provide reduced gassing over a wide temperature range.

However, if the SEI layer is excessively thickened, it actually becomes a barrier to lithium ions, increasing resistance. The thickness of the SEI layer affects power supply performance, which is very important for electric vehicles.

One way to define the cell impedance is to measure the area specific impedance. The impedance value may be determined for the entire cell or for a particular junction, such as an anode or cathode. Area Specific Impedance (ASI) is an impedance value obtained by dividing a device impedance by a surface area, and is defined as an impedance value at 1kHz (Ω) using an LCZ table or a frequency response analyzer) The measured impedance is multiplied by the surface area of the positive and negative electrodes (cm)²). Typically, the measurement is performed by applying a small (e.g., 5mV) sinusoidal voltage to the cell and measuring the resulting current response. The resulting response may be described by in-phase and out-of-phase components. The in-phase component of the impedance at 1kHz (i.e., the real or resistive component) is then multiplied by the surface area of the positive and negative electrodes (cm)²) The area specific impedance is obtained. The area specific impedance may be used to determine the impedance under the anode or cathode.

In another aspect, a battery system includes a plurality of rechargeable batteries as described in the foregoing embodiments. In one or more embodiments, the plurality of rechargeable batteries is configured to provide an operating range of about 12 volts to 15 volts. In another example, the plurality of rechargeable batteries are configured to provide an operating range of about 12 volts.

In one or more embodiments, the battery is capable of operating in a range of-30 ℃ to +70 ℃ without battery management circuitry.

In one or more embodiments, the battery system includes 4 to 16 batteries with cathodes comprising lithium iron phosphate.

In one aspect, the rechargeable battery is used in a battery system that operates as a micro-hybrid battery. Micro-hybrid batteries (or vehicles with start-stop features) are capable of stopping the internal combustion engine of the vehicle when the vehicle is stationary (such as because of a traffic light), saving up to 10% fuel over conventional vehicles. When the driver depresses the accelerator by releasing the brake pad, the engine is quickly restarted and the vehicle is then driven forward. While early micro-hybrid battery development focused on smooth engine restarts, the next generation systems considered recuperation of braking energy as one way to achieve greater fuel economy. Existing lead-acid micro-hybrid battery technology introduces some design constraints because it cannot be charged very quickly and the braking energy of the vehicle is largely lost. Batteries with lithium ion chemistry are able to accept much higher charge rates and are considered as a strong support for next generation micro-hybrid systems due to their greater fuel economy improvements.

The micro-hybrid battery may be used as a starting battery for a vehicle engine. They are close to the engine and under the hood so that it is often difficult to provide space to accommodate the larger thermal management circuits. Therefore, the battery needs to be able to start the engine without heat input at cold ambient temperatures as low as-30 ℃. In addition, batteries need to operate at the temperatures of an operating automotive engine (up to 70 ℃) for extended periods without external cooling. Conventional lithium ion batteries are subject to high impedance problems at low temperatures, which can impair their ability to start the engine. In addition, designs for increasing the power of lithium ion batteries at low temperatures tend to shorten their life at high temperatures. While lead-acid batteries have improved cold start capabilities, lead-acid batteries also suffer from shortened life span relative to lithium ion batteries used for start-stop applications.

The micro-hybrid battery may include: a battery case; a plurality of rechargeable batteries within the battery housing, wherein the rechargeable batteries comprise any of the foregoing embodiments; and a disconnection switch for switching on and off the conductive path between the plurality of rechargeable batteries and the external contact.

In one or more embodiments, the battery has a decrease in battery capacity of less than 10% after charging and discharging at 75 ℃ at a 100% depth of discharge for 300 charge and discharge cycles at a charge rate of at least 1C.

In one or more embodiments, the battery can provide at least 20% more current at 30 ℃ than a rechargeable battery lacking the additive represented by formula (1).

The nonaqueous electrolyte battery of the present invention has excellent low-temperature characteristics and long-term stability as well as excellent charge-discharge cycle characteristics when used in a micro-hybrid battery system. The present technology enhances the success of lithium ion batteries in micro-hybrid systems, particularly as starting batteries, because it greatly boosts the low temperature power of the battery, enabling it to start the vehicle engine even in the harshest low temperature environment. Furthermore, battery life growth in high temperature environments is significant because the common packaging location for starting batteries is in the engine compartment, where temperatures are typically higher than ambient temperatures when the vehicle is operating. In addition, the nonaqueous electrolyte solution of the battery of the present invention has low gassing in a temperature range.

The present application will be described in more detail below with reference to the following examples. Changes may be made in the materials, amounts, proportions, operations, etc. described hereinafter without departing from the spirit of the invention. Accordingly, the scope of the invention is not limited to the specific examples described below. The disclosed electrolyte formulations may be suitable for use in any form of battery, for example, prismatic batteries, button cells, can cells, pouch cells, and the like.

Examples of electrolyte formulations will be provided below. The electrolyte formulation has low gassing over a wide temperature range. An electrolyte formulation that reduces gassing over a wide range of temperatures is one example of an electrolyte described herein.

Example 1: electrolyte formulation

An example electrolyte formulation according to the invention comprises: LiPF₆1.0M; LiTFSI, 0.15M; EC, 40 vol.%; EMC, 45 vol.%; DEC, 10 vol.%; PC, 5 vol.%; ES, 1.5 wt.%; VC, 1 wt.%; and PS, 1.5 wt.%.

The electrolyte formulations were compared to control electrolyte formulations, as discussed below and with reference to fig. 1-10. The electrolyte formulations exhibit improved performance in low and high temperature tests relative to control electrolyte formulations.

The first control electrolyte formulation comprised: LiPF₆1.15M; EC, 30 vol.%; EMC, 55 vol.%; DEC, 10 vol.%; PC, 5 vol.%; ES, 1 wt.%; and VC, 2 wt.%. The first control electrolyte formulation contained a first additive ES comprising a sulfonyl group, but no salt solution and anti-gassing additive as in the present application were provided.

The second control electrolyte formulation comprised: LiPF₆1.15M; EC, 35 vol.%; EMC, 40 vol.%; DMC, 20 vol.%; PC, 5 vol.%; VC, 2.5 wt.%; triphenyl phosphite (TPPI), 0.2 wt.%; and PS, 2 wt.%. The second control electrolyte formulation contained PS, but no first additive or salt system containing sulfonyl groups was provided.

The above example electrolyte and control electrolyte formulations are referred to in the following description of the figures. The cell can be constructed using a lithium iron phosphate (LFP) cathode and a graphite anode, or a Nickel Cobalt Metal (NCM) cathode and a graphite anode. Other cathode/anode combinations may also be used.

Referring to fig. 1, the first capacity loss is shown for the formation (formation) and sizing (qualification) of a battery having a lithium iron phosphate (LFP) cathode and a graphite anode. An LFP/graphite cell was prepared with the electrolyte formulation described in example 1, and another LFP/graphite cell was prepared with the first control electrolyte formulation. The first capacity loss of the new electrolyte with reduced gassing during forming 101 and typing 102 shows an improvement in the first capacity loss compared to the first control electrolyte formulation in forming 103 and typing 104.

Referring to fig. 2, the first capacity loss for the formation and sizing of a battery with a Nickel Cobalt Manganese (NCM) cathode and a graphite anode is illustrated. An NCM/graphite cell was prepared with the electrolyte formulation described in example 1 and another NCM/graphite cell was prepared with the second control electrolyte formulation. The first capacity loss of the new electrolyte 201 with reduced gassing exhibits an improvement over the second control electrolyte formulation 202.

Thus, as shown in fig. 1 and 2, the first capacity loss data indicates that the new electrolyte formulations provided better first capacity loss than the first and second control electrolyte formulations under various test conditions.

Referring to fig. 3, the ac/dc resistance (ACR/NCR) impedance parity between the new electrolyte formulation and the second control electrolyte formulation in an LFP/graphite cell is illustrated. The new electrolyte formulations showed similar or lower impedance measurements for both DCR (squares) and ACR (diamonds) compared to the second control electrolyte.

Referring to fig. 4, the ACR impedance of the cell with the electrolyte in example 1 is illustrated. The new electrolyte formulation 401 exhibits improved ACR resistance in NCM/graphite cells compared to the second control electrolyte 402 of cells having an NCM cathode and a graphite anode.

Thus, as shown in fig. 3 and 4, the new electrolyte formulation maintains/reduces impedance.

Referring to fig. 5A and 5B, fig. 5A shows a hybrid pulsed power performance (HPPC) test at 23 ℃ under 1 second pulsed power, and fig. 5B shows a test at 23 ℃ under 10 second pulsed power. The new electrolyte formulation 501 exhibited a reduction in DCR during the HPPC test as compared to the first control electrolyte formulation 502. All of these electrolytes are used in LFP/graphite batteries.

Referring to fig. 6A and 6B, fig. 6A shows a hybrid pulse power performance (HPPC) test at-20 ℃ under 1 second pulsed power, and fig. 6B shows a test at-20 ℃ under 10 second pulsed power. The new electrolyte formulation 601 exhibited a significant DCR reduction during HPPC testing compared to the first control electrolyte formulation 602. Thus, the new electrolyte formulations also exhibit improved performance at low temperatures. All of these electrolytes are used in LFP/graphite batteries.

Referring to FIG. 7, power at 70% state of charge (SOC) during cold start at-30 ℃ is illustrated. The new electrolyte formulation 701, highlighted with an upper arrow (solid line), showed increased power compared to the first control electrolyte formulation 702, highlighted with a lower arrow (dashed line). Thus, the new electrolyte formulations also exhibit improved performance at low temperatures.

Referring to fig. 8, the power of the NCM/graphite cell during cold start at-30 ℃ is illustrated. The new electrolyte formulation 801 exhibited about a 20% power increase at cold start compared to the second control electrolyte formulation 802. Thus, the new electrolyte formulations exhibit improved performance at low temperatures.

Referring to fig. 9, charge and discharge cycle life of NCM cathode/graphite anode cells is illustrated. The new electrolyte (black line 901) exhibited improved charge-discharge cycle life compared to the second control electrolyte (gray line 902). Thus, the new electrolyte formulation can extend charge-discharge cycle life.

Referring to fig. 10, the gas volume of the LFP/graphite cell after storage at 60 ℃ is shown. At time 0, time 1, and time 2, the new electrolyte formulations 1001, 1002, and 1003 were compared at gassing levels to other acceptable electrolytes for pouch construction, such as the second control electrolyte formulations 1004, 1005, 1006. Therefore, the new electrolyte formulation gas evolution is lower.

The disclosed electrolyte formulations include an additive system and a salt system that provide a charge-discharge cycle system with low gassing over a wide temperature range. In one example, a disclosed formulation includes a non-aqueous electrolyte solution having a sulfonyl group, an anti-gassing agent, a second additive, and a salt system. The anti-gassing agent reduces gassing of the sulfonyl-containing additive, while the co-salt-containing salt system reduces LiPF₆Wherein the co-salt does not produce lewis acid decomposition products. Additionally, in some examples, a second additive such as FEC may be used to lower the resistance and enhance the SEI layer.

As mentioned briefly above, the new electrolyte formulations can be used in several different types of battery configurations, including pouch configurations. For example, the anti-gassing properties of the disclosed formulations can specifically improve use in pouch batteries.

Fig. 11 illustrates an exemplary bladder configuration for use with the disclosed electrolyte formulations. The pouch encloses the positive and negative plates and seals the positive and negative electrodes. For example, the pouch material may comprise a laminate comprising at least one of polyethylene, nylon, and aluminum foil. In one example, the inner assembly may be hermetically sealed in a capsule shell made of a bladder material. Other suitable materials may also be used to seal the internal components within the cell.

The diagram in fig. 11 shows various components in one example of a complete prismatic battery cell 200, including current collection tabs 304a, 304b, extension tabs 308a, 308b, welds 604a, 604b, and strips 504a, 504 b. The pouch configuration may be easily broken when a large amount of gas generation occurs within the battery. The use of the disclosed electrolyte formulations in pouch cells enables reduced gassing, improved/maintained impedance, improved cold start power, and use over a wider temperature range.

Fig. 12 illustrates a lithium-ion 12V micro-hybrid engine starting battery 1200 according to one embodiment. Consisting of a prismatic battery module 1210 having 16 20Ah cells 1220, all with a modified electrolyte composition, configured as 4s4p, capable of achieving a total capacity of 80Ah (1.06 kWh). The battery module is housed in a standard automobile starter battery enclosure 1230(EN50342-2, LN4), the external dimensions of enclosure 1230 being 175x190x315 mm. The unit includes an on-board battery management system with MOSFETs 1240 to control connections to vehicle systems. The management system includes a disconnect switch including a plurality of MOSFETs for making and breaking conductive paths between the plurality of rechargeable batteries and external contacts. The management system also includes a microprocessor configured by firmware to perform various functions, such as providing input protection and charge control, enabling/disabling circuitry to reduce current consumption and sensing the temperature and voltage of individual battery cells. The battery is connected to an operating voltage of 9-14.4V by the LIN bus protocol 1250 to support a standard 12V vehicle power grid. In some embodiments, the micro-hybrid battery has reduced thermal management circuitry. For more details, see U.S. patent application No.13/513665, which is incorporated by reference herein in its entirety.

Example 2: control group electrolyte formula

The electrolyte formulation of the control group was 1M LiPF₆The composition is as follows: EC PC EMC DEC 35:5:50:10 v/v% + VC 2 wt.%, EC representing ethylene carbonate; "PC" means propylene carbonate; "EMC" means ethyl methyl carbonate; "DEC" means diethyl carbonate; and "VC" represents vinylene carbonate.

Example 3: ES-only electrolyte formulations

The electrolyte formulation consists of 1M LiPF₆Composition, wherein EC: PC: EMC: DEC ═ 35:5:50:10 v/v%) + ES 1 wt%. Here, "ES" means vinyl sulfite. The addition of ES decreased the impedance because ES reacted with the anode to produce a Solid Electrolyte Interface (SEI) that was more ionically conductive than the control electrolyte described above. However, during formation, a battery having this electrolyte (i.e., an electrolyte containing only the ES additive) may not be charged because the SEI is unstable and may be in the decomposition phaseA large amount of gas is generated.

Fig. 13 illustrates this effect, where a carbon-based anode is first charged with a lithium half-cell (the "forming" phase of the SEI curve). A slurry is coated onto a 10 μm thick copper foil, the slurry comprising: 92 wt% artificial graphite, 4 wt% conductive graphite additive and 4 wt% polyvinylidene fluoride (PVDF) binder dissolved in N-methylpyrrolidone (NMP), and then dried in an oven and calender-molded to form an anode.

The voltage drop shown in fig. 13 indicates the formation of an electrolyte (formation). However, the voltage after the drop did not reach 0V (which would otherwise be 0V if the graphite was fully lithiated), indicating that the electrolyte was continuously decomposing and lacking in effective SEI formation (see, e.g., Abe et al, Electrochimia Acta 49(26),46l3-4622 (2004)).

Example 4: modified electrolyte formulation (ES + VC)

The "modified" electrolyte formulation is made up of 1M LiPF₆Composition wherein EC: PC: EMC: DEC ═ 35:5:50:10 v/v% + VC 2 wt.% + ES 1 wt.%.

Fig. 14 is a graph showing formation curves of secondary batteries having the electrolyte composition of example 3 ("ES only") and the electrolyte composition of example 4 ("ES + VC" "" modified "). The applied current steps are also shown. Both cells used the anode of example 3. A slurry was coated on a 20 μm thick aluminum foil, the slurry comprising: 92 wt.% LiFeO in N-methylpyrrolidone (NMP)₄4 wt.% of a conductive carbon additive and 4 wt.% of a polyvinylidene fluoride (PVDF) binder, then dried in an oven and calendered to form the cathodes of both cells. Prismatic cells using the cathode, anode and polyolefin microporous separator were assembled with the electrolyte, as would be understood by those skilled in the art.

As shown in fig. 14, the addition of VC and ES can reduce the battery resistance and contribute to the formation of a stable SEI layer. The voltage drop seen in the "ES-only" curve is indicative of electrolyte decomposition and gassing. The monotonic voltage increase of the "ES + VC" curve indicates the formation of a stable SEI layer.

The addition of ES as a companion additive in addition to VC in the organic electrolyte enables the appropriate formation of SEI in lithium ion batteries and the realization of low-resistance batteries.

Example 5: low temperature behavior

The behavior of secondary batteries with ("control") modified electrolyte and without the modified electrolyte was compared to glass fiber separator (AGM) lead acid batteries at low temperatures. The modified electrolyte cell is described in example 4(ES + VC). The electrolyte composition of the "control" cell was substantially the same as the modified cell except that the electrolyte composition did not contain ES or VC.

The results of a cold start at 7V for 10 seconds in fig. 15A (for a 60Ah battery) and fig. 15B (for an 80Ah battery). The difference in performance reflects the improvement that can be achieved using the modified electrolytes described herein.

As the graph in the figure shows, the battery with the modified electrolyte composition can provide 20-30% more current (between-20 ℃ and-15 ℃) than the control battery, and its cold start performance is the same as that of the lead-acid battery (-17 ℃).

Example 6: high temperature storage

The disclosed modified electrolyte cell (ES + VC of example 4) also exhibited improved high-temperature storage performance compared to the control cell. As shown in fig. 16A and 16B, the modified electrolyte battery exhibited less capacity loss after storage at high temperature (55 ℃) compared to the control group battery. Furthermore, as shown in fig. 17A and 17B, the modified electrolyte battery lost less power after storage at high temperature (55 ℃) relative to the control group.

Example 7: high temperature charge-discharge cycle

As shown in fig. 18A and 18B and fig. 19A and 19B, the modified electrolyte battery (ES + VC in example 4) also exhibited improved performance at high temperature charge-discharge cycles over other predominantly competing lithium ion batteries at various temperatures (45-75 ℃), charge-discharge rates (1C-10C) and number of charge-discharge cycles (300-5000).

Furthermore, as shown in fig. 20, the modified electrolyte cell (ES + VC in example 4) had a lower increase in resistance at 60 ℃ compared to the "control" cell.

As described herein, the modified electrolyte battery has improved low temperature characteristics and long-term stability, and thus a variety of different applications can be expected.

The voltage characteristics of the batteries make them particularly suitable for 12 volt battery replacement. Lithium metal phosphate (preferably lithium iron phosphate) cells constituting about 12 volts are particularly suitable for 4 cells.

In telecommunications, modified electrolyte secondary batteries can replace lead-acid batteries (used during power outages to maintain the base station in normal operation) because lead-acid batteries are susceptible to rapid degradation at high temperatures.

In transportation, the demand for fuel economy is greater and more electrical load is placed on the battery rather than the engine. This is particularly true on micro-hybrid cars, trucks, and buses that use "stop-and-start" technology, which requires the engine to be turned off when the driver decelerates or stops the vehicle. The modified electrolyte battery can enhance engine startability by improved cold start performance while extending the service life at high temperature storage, for example, twice the service life of a lead acid battery in micro-hybrid applications. The ability to extend temperature can also reduce the weight and cost of the battery by reducing or eliminating the thermal management circuitry typically used in extreme temperature conditions.

Reducing the cost and weight of the battery may also be applied to defense applications requiring wider operating temperatures, such as ground vehicles, space and satellite applications, aviation aircraft and portable personal devices, among others.

The foregoing discussion is to be understood as illustrative and not restrictive in any sense. While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

The corresponding structures, materials, acts, and equivalents of all means or method plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

Finally, it is to be understood that the articles, systems and methods described above are embodiments of the present invention, non-limiting examples, and are intended to encompass variations and extensions. Accordingly, the present invention includes all novel and nonobvious combinations and subcombinations of the articles, systems and methods disclosed herein, as well as any and all equivalents thereof.