阅读说明：本技术 用于高电压锂离子电池的基于聚(酮)的聚合物电解质 (Poly (ketone) -based polymer electrolytes for high voltage lithium ion batteries ) 是由 M.阿扎加萨米 K.西瓦南丹 H.B.埃托尼 J.P.麦罗亚 G.桑索里泽 K.R.贾德尔 于 2017-12-16 设计创作，主要内容包括：已经合成了新的基于聚(酮)的聚合物。当这些聚合物与电解质盐混合时,此类聚合物电解质在锂电池电芯中显示出优异的电化学氧化稳定性。它们的稳定性以及它们优异的离子传导性质使它们尤其适于作为高能量密度锂电池电芯中的电解质。(New poly (ketone) -based polymers have been synthesized. When these polymers are mixed with electrolyte salts, such polymer electrolytes exhibit excellent electrochemical oxidation stability in lithium battery cells. Their stability and their excellent ion-conducting properties make them particularly suitable as electrolytes in high energy density lithium battery cells.)

1. A polymer comprising:

a ketone-based polymer structure as described below:

a is an integer of 1 to 10;

b is an integer of 1 to 10;

n is an integer from 1 to 1000;

each of Z and Z₁Independently selected from:

wherein c is an integer from 0 to 10;

each R₁Independently selected from hydrogen, methyl, ethyl, propyl and isopropyl; and is

Each R is independently selected from:

wherein d, e, and f are integers, and each integer is independently 0 to 10; and is

Each X is independently selected from hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl.

2. The polymer of claim 1, further comprising an electrolyte salt, wherein the polymer is an electrolyte.

3. The polymer of claim 2, further comprising ceramic electrolyte particles.

4. The polymer of claim 1, wherein the polymer is crosslinked.

5. The polymer of claim 4, further comprising an electrolyte salt, wherein the polymer is an electrolyte.

6. A positive electrode comprising:

a positive electrode active material; and

a catholyte comprising the electrolyte of claim 2;

wherein positive electrode active material particles are mixed together with the catholyte.

7. The positive electrode of claim 6, wherein the catholyte further comprises a solid polymer electrolyte.

8. The positive electrode of claim 6, wherein the catholyte further comprises ceramic electrolyte particles.

9. The positive electrode of claim 6 wherein said catholyte is crosslinked.

10. The positive electrode of claim 6, wherein the positive electrode active material is selected from the group consisting of lithium iron phosphate, lithium metal phosphates, vanadium pentoxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, magnesium rich lithium nickel cobalt manganese oxide, lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof.

11. The positive electrode of claim 6, wherein the electrolyte salt is a lithium salt.

12. An electrochemical cell, comprising:

an anode configured to absorb and release lithium ions;

a cathode comprising cathode active material particles, an electron conducting additive, and a first catholyte;

a current collector adjacent the outer surface of the cathode; and

a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode;

wherein the first catholyte comprises the electrolyte of claim 2, and the electrolyte salt is a lithium salt.

13. The electrochemical cell of claim 12, wherein the first catholyte further comprises a solid polymer electrolyte.

14. The electrochemical cell of claim 12, wherein the first catholyte and the separator electrolyte are the same.

15. The electrochemical cell of claim 12, wherein the separator electrolyte comprises a solid polymer electrolyte.

16. The electrochemical cell of claim 12, further comprising a cover layer between the cathode and the separator region, the cover layer comprising a second catholyte comprising the electrolyte of claim 2.

17. The electrochemical cell of claim 16, wherein the first catholyte and the second catholyte are the same.

18. The electrochemical cell of claim 12, wherein the anode comprises a material selected from the group consisting of lithium metal, lithium alloys, lithium titanate, graphite, and silicon.

19. The electrochemical cell of claim 12, wherein the first catholyte further comprises ceramic electrolyte particles.

20. The electrochemical cell of claim 12, wherein the first catholyte is crosslinked.

Technical Field

The present invention relates generally to electrolytes for lithium batteries, and more particularly to electrolytes particularly suitable for use in cathodes and at high voltages.

More and more lithium battery manufacturers are using next generation cathode materials such as NCA (lithium nickel cobalt aluminum oxide), NCM (lithium nickel cobalt manganese oxide) and high energy NCM (HE-NCM-magnesium rich lithium nickel cobalt manganese oxide) to take advantage of their potential high gravimetric energy density (up to 300-. Cells made with such oxide cathode materials typically operate at higher voltages (e.g., up to 4.7V) than cells made with olivine cathode materials such as LFP (lithium iron phosphate) (e.g., 3.6-3.8V). Electrolytes that are stable at the lower voltages of LFP cells can be difficult to operate at higher voltages, especially in the cathode. Oxidative forms of degradation may lead to capacity degradation early in the cell life.

Therefore, there is a need to develop electrolytes that are particularly well suited for operation under the high voltage conditions of the next generation of cathode materials.

Background of the invention.

Summary of The Invention

In one embodiment of the present invention, a polymer is described. The polymer includes a ketone-based polymer structure described by the formula:

wherein a is an integer from 1 to 10; b is an integer of 1 to 10; and n is an integer from 1 to 1000. Each of Z and Z₁Independently selected from:

wherein c is an integer from 0 to 10; each R₁Independently selected from hydrogen, methyl, ethyl, propyl and isopropyl; and each R is independently selected from:

wherein d, e, and f are integers, and each integer is independently 0 to 10; and each X is independently selected from hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl.

In some embodiments of the invention, any of the polymers described herein are mixed with an electrolyte salt and can be used as a polymer electrolyte.

In some embodiments of the invention, any of the polymer electrolytes described herein further comprise ceramic electrolyte particles.

In some arrangements, any of the polymers described herein are crosslinked and may or may not be mixed with an electrolyte salt for use as a polymer electrolyte.

In one embodiment of the invention, the positive electrode includes a positive electrode active material; and a catholyte comprising any electrolyte described herein. The positive electrode active material particles are mixed with the catholyte. The catholyte may also include a solid polymer electrolyte. The catholyte may also include ceramic electrolyte particles. The catholyte may be crosslinked. The catholyte may contain an electrolyte salt that is a lithium salt.

The positive electrode active material may be any one of lithium iron phosphate, lithium metal phosphate, vanadium pentoxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, magnesium rich lithium nickel cobalt manganese oxide, lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof.

In another embodiment of the invention, an electrochemical cell includes an anode configured to absorb and release lithium ions; a cathode comprising cathode active material particles, an electron conducting additive, and a first catholyte; a current collector adjacent the outer surface of the cathode; and a separator region between the anode and the cathode, the separator region comprising a separator electrolyte configured to facilitate movement of lithium ions back and forth between the anode and the cathode. The first catholyte may include any electrolyte described herein. The first catholyte may also contain ceramic electrolyte particles. The first catholyte may be crosslinked. The electrolyte salt may be a lithium salt.

The first catholyte and/or the separator electrolyte may also contain a solid polymer electrolyte. In one arrangement, the first catholyte is the same as the separator electrolyte.

In one arrangement, there is a cover layer between the cathode and separator regions. The cover layer includes a second catholyte, which may be any electrolyte disclosed herein. The first catholyte and the second catholyte may or may not be the same.

The anode may contain any one of lithium metal, lithium alloy, lithium titanate, graphite, and silicon.

Brief description of the drawings

The foregoing aspects and others will become readily apparent to those skilled in the art from the following description of the illustrative embodiments, when read in conjunction with the accompanying drawings.

Fig. 1 is a graph showing cyclic voltammetry data for a ketone repeat structure according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of one configuration of a lithium battery cell containing electrolyte used in both the cathode and separator according to an embodiment of the invention.

Fig. 3 is a schematic illustration of another configuration of a lithium battery cell containing a catholyte and a separator electrolyte different from the catholyte, according to an embodiment of the invention.

Fig. 4 is a schematic diagram of another configuration of a lithium battery cell containing a catholyte and a cathode capping layer, according to an embodiment of the invention.

Detailed Description

Embodiments of the present invention are illustrated in the context of ketone polymers, which may be used as electrolytes or electrolyte additives in lithium battery cells and the like. However, the skilled person will readily appreciate that the materials and methods disclosed herein will have application in many other areas where high voltage electrolytes are required, particularly where long term stability is important.

These and other objects and advantages of the present invention will become more fully apparent from the following description taken in conjunction with the accompanying drawings.

All publications mentioned herein are incorporated herein by reference in their entirety for all purposes as if fully set forth herein.

In the present disclosure, the terms "negative electrode" and "anode" are both used to describe a negative electrode. Likewise, the terms "positive electrode" and "cathode" are both used to describe a positive electrode.

It is to be understood that the term "lithium metal" or "lithium foil" as used herein for the negative electrode describes both pure lithium metal and lithium-rich metal alloys, as is known in the art. Examples of lithium-rich metal alloys suitable for use as the anode include Li-Al, Li-Si, Li-Sn, Li-Hg, Li-Zn, Li-Pb, Li-C, or any other Li metal alloy suitable for use in a lithium metal battery. Other negative electrode materials that may be used in embodiments of the invention include materials in which lithium may be intercalated, such as graphite, as well as other materials that may absorb and release lithium ions, such as silicon, germanium, tin, and alloys thereof. Many of the embodiments described herein relate to batteries having a solid polymer electrolyte that functions as both an electrolyte and a separator. As is well known in the art, batteries with liquid electrolytes use inactive separator materials other than liquid electrolytes.

The following explanations are used throughout this disclosure: each variable is "independently selected" from the provided list. An example of such use can be found with reference to some X groups in the polymer structure of the present invention where there are many X. This example is "each X can be independently selected from hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl". This explanation is intended to indicate that for a particular X in the structure, any group in the list can be used. In selecting a group for another X in the structure, any group in the list can be used without regard to the selection made for the other X group. Thereby, the following arrangements are possible: all xs may be the same, all xs may be different, or some xs may be the same and some may be different.

The molecular weights given herein are number average molecular weights.

The term "solid polymer electrolyte" is used herein to refer to a polymer electrolyte that is solid at the operating temperature of the battery cell. Examples of useful battery cell operating temperatures include room temperature (25 ℃), 40 ℃, and 80 ℃.

In this disclosure, a range of values is given for a number of variables. It is to be understood that the possible values of any variable also include any range included within the given range.

Li in Molecular Dynamics (MD) based simulations⁺Repeated observation of interactions with other atoms, it appears that Li⁺Coordinated to a portion of the negatively charged atoms in the polymer electrolyte, or, when Li salt is insoluble in the polymer, to the negatively charged anion of the salt that has been added to the polymer to form the electrolyte. Using polyethylene oxide (PEO), Li⁺Coordinated to a portion of the negatively charged oxygen atoms in the PEO. Similarly, in poly (ketones), Li⁺Coordinated to the partially negatively charged oxygen in the carbonyl group.

Poly (ketone):

in some embodiments of the invention, the general structure of the ketone-based polymers is shown below. The ketone-based polymer has functional side chains Z and Z₁They may be linked directly as shown or via an extendable alkyl chain (not shown).

Each Z, Z₁And R is independently selected from the following list; a is an integer of 0 to 10; b is an integer of 1 to 10; and n is an integer from 1 to 1000.

To Z and Z₁C is an integer of 0 to 10, and R₁Can be hydrogen, methyl, ethyl, propyl or isopropyl.

For R, each d, e, and f is independently an integer from 0 to 10, and each X can be independently selected from hydrogen, fluoro, methyl, ethyl, isopropyl, and trifluoromethyl.

In another embodiment of the present invention, particles of a ceramic electrolyte are mixed into a poly (ketone) -based polymer electrolyte to form an enhanced composite electrolyte having excellent ion transport and mechanical properties. Such composite electrolytes may be used in the separator region or cathode of a lithium battery cell. Examples of ceramic electrolytes that can be used in admixture with poly (ketone) -based polymer electrolytes include, but are not limited to, those shown in table 1 below.

TABLE 1

Exemplary ceramic conductors for use as additives in poly (ketone) -based polymer electrolytes

Denotes the components are mixed together.

Table 2 below shows simulated lithium ion transport properties of various poly (ketone) -based polymers. The listed poly (ketone) polymers exhibit excellent lithium ion transport properties. In particular, polydiones (entries 1 and 2) and polytrienones (entries 4 and 5) are promising candidates for lithium ion transport applications.

TABLE 2

Lithium transport properties of poly (ketone) -based polymers

Item(s)	Polymer and method of making same	Chemical structure	Concentration of LiTFSI (% by weight)	κ (S/cm)	t +
						1	Poly (1, 3-nonyl diketone)		30	6.1 x 10-4	0.68
2	Poly (cis-non-6-ene-1, 3-dione)		30	1.21 x 10-3	0.67
						3	Polyhexylglyoxal		30	8.9 x 10-5	0.81
4	Poly (nonyl-1, 3, 5-trione)		30	9.5 x 10-4	0.75
						5	Poly (nonyl-1, 2, 3-trione)		30	1.1 x 10-4	0.59

Chemical stability of ketone groups

Table 3 shows the Ionization Potential (IP) and energy difference between keto tautomers modeled using Quantum Chemistry (QC) (method: M06-HF/aug-cc-pvtz// PBE 0/aug-cc-pvtz).

TABLE 3

Ionization Potential (IP) and energy difference between keto tautomers

。

Electrochemical stability of ketone groups

Cyclic voltammetry was measured using a three-electrode system comprising a Pt button working electrode, a Pt wire counter electrode, and a quasi-reference electrode consisting of a 10 mM AgNO immersed in a glass tube with a Vycor frit attached₃Ag filaments in a solution of 0.1M tetrabutylammonium hexafluorophosphate. The quasi-reference electrode was first aligned to 0.1M lithium tetrafluoroborate (LiBF) in propylene carbonate₄) Was calibrated to obtain E in a 10 mM ferrocene solution_ox(ferrocene/ferrocene ion) = 0.058V (vs Ag/Ag)⁺). The same ferrocene solution was then used to calibrate a lithium reference electrode (E)_ox(ferrocene/ferrocene ion) = 3.35-3.39V (relative to Li/Li)⁺)). The cyclic voltammetry is used for the 0.1M LiBF in the propylene carbonate₄Was performed at a scan rate of 5 mV/s and in a 0.1M solution of acetylacetone (dione). The cyclic voltammetry data was then vs. Li/Li⁺Normalized to reflect oxygen in lithium cellsChemical stability, since electrolyte materials made of acetylacetone can interact with lithium electrodes in practical battery cells. The results are shown in the graph of fig. 1. As shown in fig. 1, acetylacetone has electrochemical oxidation stability up to at least 4.5V, and the current density response is small even at 4.5V. This clearly shows that this type of ketone-based polymer system is stable at high voltages and can be used as an electrolyte in high energy density lithium ion batteries.

Cell design including ketone-based polymers

In one embodiment of the present invention, as shown in fig. 2, a lithium battery cell 200 has an anode 220 configured to absorb and release lithium ions. The anode 220 may be a lithium or lithium alloy foil, or it may be made of a material (e.g., graphite or silicon) into which lithium ions may be absorbed. Other options for anode 220 include, but are not limited to, lithium titanate and lithium-silicon alloys. The lithium battery cell 200 also has a cathode 240 that includes cathode active material particles 242, an electronically conductive additive such as carbon black (not shown), a current collector 244, a catholyte (electrolyte in the cathode) 246, and optionally a binder (not shown). In one arrangement, the catholyte 246 comprises any of the ketone-based polymer electrolytes disclosed above. In another arrangement, the catholyte 246 comprises a mixture or combination of other solid polymer electrolytes and ketone-based polymer electrolytes. A separator region 260 is present between anode 220 and cathode 240. The catholyte 246 extends all the way into the separator region 260 and facilitates lithium ions moving back and forth between the anode 220 and the cathode 240 as the cell 200 is cycled. The electrolyte 246 in the separator region 260 is the same as the catholyte in the cathode 240.

In another embodiment of the present invention, as shown in fig. 3, the lithium battery cell 300 has an anode 320 configured to absorb and release lithium ions. The anode 320 may be a lithium or lithium alloy foil, or it may be made of a material (e.g., graphite or silicon) into which lithium ions may be absorbed. Other options for anode 320 include, but are not limited to, lithium titanate and lithium-silicon alloys. The lithium battery cell 300 also has a cathode 340 that includes cathode active material particles 342, an electronically conductive additive such as carbon black (not shown), a current collector 344, a catholyte 346, and an optional binder (not shown). In one arrangement, the catholyte 346 includes any of the ketone-based polymer electrolytes disclosed above. In another arrangement, the catholyte 346 includes a mixture or combination of other solid polymer electrolytes with ketone-based polymer electrolytes. A separator electrolyte 360 is present between the anode 320 and the cathode 340. The separator electrolyte 360 facilitates lithium ions to move back and forth between the anode 320 and the cathode 340 as the cell 300 is cycled. The separator electrolyte 360 can include any electrolyte suitable for use in a lithium battery cell. In one arrangement, the separator electrolyte 360 contains a liquid electrolyte impregnated into a porous plastic material (not shown). In another arrangement, the separator electrolyte 360 contains a viscous liquid or gel electrolyte. In another arrangement, the separator region 360 contains a solid polymer electrolyte in which the ketone-based polymer is immiscible.

In another embodiment of the present invention, a battery cell having a third configuration is described. Referring to fig. 4, the lithium battery cell 400 has an anode 420 configured to absorb and release lithium ions. The anode 420 may be a lithium or lithium alloy foil, or it may be made of a material (e.g., graphite or silicon) into which lithium ions may be absorbed. Other options for anode 420 include, but are not limited to, lithium titanate and lithium-silicon alloys. The lithium battery cell 400 also has a cathode 450 that includes cathode active material particles 452, an electronically conductive additive (not shown), a current collector 454, a catholyte 456, an optional binder (not shown), and a cover layer 458. In one arrangement, the electrolyte in the cover layer 458 is the same as the catholyte 456. In another arrangement, the electrolyte in capping layer 458 is different from catholyte 456. Cover layer 458 and/or catholyte 456 may contain any ketone-based polymer electrolyte, or a mixture or combination of other solid polymer electrolytes with the ketone-based polymer electrolytes or electrolyte additives (in the solid polymer electrolyte matrix) disclosed herein. In one arrangement, the capping layer 458 is a solid electrolyte layer. A separator region 460 is present between the anode 420 and the cathode 450. The separator region 460 contains an electrolyte that facilitates lithium ions to move back and forth between the anode 420 and the cathode 450 as the cell 400 is cycled. The separator region may include any electrolyte suitable for use in a lithium battery cell. In one arrangement, the separator electrolyte 460 contains a liquid electrolyte impregnated into a porous plastic material (not shown). In another arrangement, the separator electrolyte 460 contains a viscous liquid or gel electrolyte. In another arrangement, the separator region 460 contains a solid polymer electrolyte in which the ketone-based polymer is immiscible.

The solid polymer electrolyte used in the separator region, such as separator region 360 or 460, can be any electrolyte suitable for Li batteries. Of course, many such electrolytes also include one or more electrolyte salts that help provide ionic conductivity. Examples of such electrolytes include, but are not limited to, block copolymers containing ion-conducting blocks and structural blocks that constitute the ion-conducting phase and the structural phase, respectively. The ionically conductive phase may contain one or more linear polymers such as polyethers, polyamines, polyimides, polyamides, polyalkylcarbonates, polynitriles, perfluoropolyethers, fluorocarbon polymers substituted with high dielectric constant groups such as nitriles, carbonates, and sulfones, and combinations thereof. In one arrangement, the ionically conductive phase contains one or more ketone-based polymers disclosed herein. The linear polymers may also be used in combination with polysiloxanes, polyalkoxysiloxanes, polyphosphazines, polyolefins and/or polydienes as graft copolymers to form the conductive phase. The structural phase may be composed of a polymer, such as polystyrene, hydrogenated polystyrene, polymethacrylate, poly (methyl methacrylate), polyvinylpyridine, polyvinylcyclohexane, polyimide, polyamide, polypropylene, polyolefin, poly (t-butyl vinyl ether), poly (cyclohexyl methacrylate), poly (cyclohexyl vinyl ether), poly (t-butyl vinyl ether), polyethylene, poly (phenylene ether), poly (2, 6-dimethyl-1, 4-phenylene ether), poly (phenylene sulfide sulfone), poly (phenylene sulfide ketone), poly (phenylene sulfide amide), polysulfone, a fluorocarbon such as polyvinylidene fluoride, or a copolymer containing styrene, methacrylate, or vinylpyridine. This is particularly useful if the structural phase is rigid and is glassy or crystalline.

With reference to the embodiments described in fig. 2,3 and 4, suitable cathode active materials include, but are not limited to, LFP (lithium iron phosphate), LMP (lithium metal phosphate, where the metal may be Mn, Co or Ni), V₂O₅(vanadium pentoxide), NCA (lithium nickel cobalt aluminum oxide), NCM (lithium nickel cobalt manganese oxide), high energy NCM (HE-NCM-magnesium rich lithium nickel cobalt manganese oxide), lithium manganese spinel, lithium nickel manganese spinel, and combinations thereof. Suitable electronically conductive additives include, but are not limited to, carbon black, graphite, vapor grown carbon fibers, graphene, carbon nanotubes, and combinations thereof. A binder may be used to hold the cathode active material particles and the electron conductive additive together. Suitable binders include, but are not limited to PVDF (polyvinylidene fluoride), PVDF-HFP (poly (vinylidene fluoride-co-hexafluoropropylene)), PAN (polyacrylonitrile), PAA (polyacrylic acid), PEO (polyethylene oxide), CMC (carboxymethylcellulose), and SBR (styrene-butadiene rubber).

Examples

The following examples provide details relating to the manufacture of poly (ketone) -based polymers according to the present invention. It should be understood that the following is representative only, and that the invention is not limited by the details set forth in the examples.

In one example, a synthetic route to produce poly (nonyl-1, 3-dione) is depicted below.

(1) Synthesis of (diallylacetone):

to a solution of acetylacetone (2 g, 20 mmol) in anhydrous cyclohexane (30 ml) was added sodium hydride (0.958 g, 40 mmol), and stirred at 20 ℃ for 30 minutes. Subsequently, Tetramethylethylenediamine (TMEDA) (5.9 ml, 40 mmol) was added to the reaction mixture followed by slow addition of sec-BuLi (30.6 ml, 40 mmol) at 0 ℃. The reaction was allowed to proceed at 20 ℃ for 24 hours. Allyl bromide (3.44 ml, 40 mmol) was then added and the reaction continued for an additional 4 hours at 20 ℃. The reaction was quenched by slow addition of water, the product was extracted into ethyl acetate and rotary evaporation gave the crude product. The crude product was subjected to column chromatography using an ethyl acetate/hexane mixture (5: 95) to give 1.0 g of 1 (30% yield).

(2) The synthesis of (2):

to a solution of (1) (0.8 g, 4.4 mmol) in dichloroethane (10 ml) was added Grubb's first generation catalyst (18 mg, 0.02 mmol) and stirred at 60 ℃ under high vacuum for 16 h. The polymer (2) was isolated as a brown viscous liquid by precipitation in methanol. The amount of the obtained polymer (2) was 0.13 g (20% yield).

(3) The synthesis of (2):

to a solution of (2) (0.5 g, 0.3 mmol) in ethyl acetate (10 ml) was added Pd/C (0.1 g) and at room temperature in n-H₂Stir vigorously under pressure for 24 hours. The polymer (3) was obtained in the form of a white powder by precipitation in methanol. The amount of the obtained polymer (3) was 0.4 g (80% yield).

The invention has been described herein in considerable detail in order to provide those skilled in the art with information relevant to the application of the novel principles and the construction and use of such specialized components as are required. However, it is to be understood that the invention may be carried out by different equipment, materials and devices, and that various modifications, both as to the equipment and operating procedures, may be accomplished without departing from the scope of the invention itself.