阅读说明：本技术 一种凝胶电解质组合物及其制备方法、凝胶电解质及其制备方法和应用 (Gel electrolyte composition and preparation method thereof, gel electrolyte and preparation method and application thereof ) 是由 李晓龙 宋文锋 王鹏 于 2021-08-31 设计创作，主要内容包括：本发明涉及锂电池技术领域,具体而言,涉及一种凝胶电解质组合物及其制备方法、凝胶电解质及其制备方法和应用。本发明的凝胶电解质组合物,包括第一聚合单体、第二聚合单体、锂盐、引发剂和溶剂；所述第一聚合单体包括甲基丙烯酸甲酯、苯乙烯、醋酸乙烯酯、丙烯腈、氟代丙烯酸酯、聚乙二醇二丙烯酸酯和聚乙二醇丙烯酸酯中的至少一种；所述第二聚合单体包括含有碳碳双键和/或碳氮三键的磷酸酯类物质。本发明的凝胶电解质组合物可用于制备具有优异导电性、阻燃性的凝胶电解质。阻燃性磷酸酯单体引入聚合物框架中,可极大地减少电池漏液的风险,得到的凝胶电解质具有阻燃和高电导率特点,提升了电池的安全性能。(The invention relates to the technical field of lithium batteries, in particular to a gel electrolyte composition and a preparation method thereof, a gel electrolyte and a preparation method and application thereof. The gel electrolyte composition comprises a first polymeric monomer, a second polymeric monomer, a lithium salt, an initiator and a solvent; the first polymerized monomer comprises at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, fluoroacrylate, polyethylene glycol diacrylate and polyethylene glycol acrylate; the second polymeric monomer comprises phosphate substances containing carbon-carbon double bonds and/or carbon-nitrogen triple bonds. The gel electrolyte composition can be used for preparing gel electrolyte with excellent conductivity and flame retardance. The flame-retardant phosphate monomer is introduced into the polymer frame, so that the risk of battery leakage can be greatly reduced, the obtained gel electrolyte has the characteristics of flame retardance and high conductivity, and the safety performance of the battery is improved.)

1. A gel electrolyte composition comprising a first polymeric monomer, a second polymeric monomer, a lithium salt, an initiator, and a solvent;

the first polymerized monomer comprises at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, fluoroacrylate, polyethylene glycol diacrylate and polyethylene glycol acrylate;

the second polymeric monomer comprises phosphate substances containing carbon-carbon double bonds and/or carbon-nitrogen triple bonds.

2. The gel electrolyte composition according to claim 1, wherein the second polymeric monomer comprises at least one of dimethyl vinylphosphate, diethyl vinylphosphonate, diethyl allylphosphonate, and dimethyl isopropenylphosphonate;

preferably, the molar ratio of the first polymerized monomer to the second polymerized monomer is (0.1-30): 1, preferably (0.2-5): 1.

3. The gel electrolyte composition according to claim 1, further comprising a plasticizer;

preferably, the plasticizer comprises at least one of vinylene carbonate, fluoroethylene carbonate, propylene carbonate and triethyl phosphate;

preferably, the mass of the plasticizer is 0.5% to 10% of the mass of the gel electrolyte composition;

preferably, the initiator comprises at least one of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide;

preferably, the lithium salt comprises lithium hexafluorophosphate.

4. The gel electrolyte composition according to claim 1, wherein a ratio of a total mass of the first and second polymeric monomers to a mass of the solvent is (1-99): (1-99), preferably (2-70): (30-98);

preferably, the solvent comprises ethylene carbonate, diethyl carbonate and dimethyl carbonate, and the mass ratio of the ethylene carbonate to the diethyl carbonate to the dimethyl carbonate is (1-4): (1-3): (1-3).

5. The method for preparing the gel electrolyte composition according to any one of claims 1 to 4, comprising the steps of:

mixing the above components.

6. A method for preparing a gel electrolyte, comprising the steps of:

the gel electrolyte composition according to any one of claims 1 to 4, which is subjected to polymerization under heating;

preferably, the gel electrolyte composition is subjected to the polymerization reaction in a cell or a glass container.

7. A method for preparing a gel electrolyte according to claim 6, wherein the temperature of the polymerization reaction is 50 to 110 ℃, preferably 50 to 80 ℃.

8. A method for preparing a gel electrolyte according to claim 6, wherein the polymerization reaction time is 1-48 h, preferably 6-24 h.

9. The gel electrolyte prepared by the method for preparing the gel electrolyte according to any one of claims 6 to 8.

10. A lithium ion battery comprising the gel electrolyte of claim 9.

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a gel electrolyte composition and a preparation method thereof, a gel electrolyte and a preparation method and application thereof.

Background

Lithium Ion Batteries (LIBs) have the characteristics of high energy density, high operating voltage, long cycle life and environmental friendliness. The battery manufacturer selects and optimizes the materials, the electrodes, the battery cores, the modules and the packs layer by layer, and develops and manufactures the battery products meeting the requirements of customers. The traditional lithium ion battery is a liquid system and faces a plurality of safety hazards in the long-term use process, such as drying of electrolyte, pollution and ignition caused by leakage, and even explosion. Researchers have generally solved the safety problem of the electrolyte from the root of the battery by using a locally over-concentrated/high-concentrated electrolyte or adding a phosphate/fluoro additive to the electrolyte. The method benefits from that the electrolyte containing phosphate can capture hydrogen radicals (H) in the combustion process, thereby achieving the effects of flame retardance and non-combustion of the electrolyte. However, this method cannot fix the phosphate free in the electrolyte, and after the cell is damaged, the electrolyte still flows out of the cell, which causes pollution to the working environment.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

The invention relates to a gel electrolyte composition, which comprises a first polymerized monomer, a second polymerized monomer, a lithium salt, an initiator and a solvent;

the first polymerized monomer comprises at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, fluoroacrylate, polyethylene glycol diacrylate and polyethylene glycol acrylate;

the second polymeric monomer comprises phosphate substances containing carbon-carbon double bonds and/or carbon-nitrogen triple bonds.

The gel electrolyte composition can be used for preparing gel electrolyte with excellent conductivity and flame retardance.

According to another aspect of the present invention, the present invention also relates to a method for preparing the gel electrolyte composition, comprising the steps of:

mixing the above components.

The preparation method of the gel electrolyte composition is simple and easy to implement, and all the components are uniformly mixed.

According to another aspect of the present invention, the present invention also relates to a method for preparing a gel electrolyte, comprising the steps of:

the gel electrolyte composition is subjected to polymerization reaction under the heating condition;

preferably, the gel electrolyte composition is subjected to the polymerization reaction in a cell or a glass container.

The gel electrolyte composition of the invention is polymerized under the heating condition to obtain the gel electrolyte.

According to another aspect of the invention, the invention also relates to the gel electrolyte prepared by the preparation method of the gel electrolyte.

The flame-retardant phosphate ester monomer is introduced into the polymer frame instead of being dissociated in the liquid electrolyte, so that the risk of leakage of the battery is greatly reduced; the synthesized gel electrolyte has the characteristics of flame retardance and high conductivity, and the safety performance of the battery is improved.

According to another aspect of the invention, the invention also relates to a lithium ion battery comprising a gel electrolyte as described above.

The lithium ion battery has excellent conductivity and flame retardance.

Compared with the prior art, the invention has the beneficial effects that:

(1) the gel electrolyte composition can be used for preparing gel electrolyte with excellent conductivity and flame retardance.

(2) The preparation method of the gel electrolyte composition is simple and easy to implement, and all the components are uniformly mixed.

(3) According to the invention, the flame-retardant phosphate is anchored in the polymer skeleton, so that the traditional gel polymer has the characteristic of flame retardance without losing the electrical property of the material; the gel electrolyte composition is subjected to polymerization reaction under the heating condition, so that a gel electrolyte can be obtained; the battery produced by the one-step liquid injection-polymerization process has the characteristic of high safety.

(4) The flame-retardant phosphate ester monomer is introduced into the polymer frame instead of being dissociated in the liquid electrolyte, so that the risk of leakage of the battery is greatly reduced; the synthesized gel electrolyte has the characteristics of flame retardance and high conductivity, and the safety performance of the battery is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is an optical picture of a gel electrolyte obtained in example 1;

FIG. 2 is a photograph showing a burning test of the gel electrolyte obtained in example 1;

fig. 3 is a room temperature impedance spectrum of the gel electrolyte obtained in example 1.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

According to an aspect of the present invention, the present invention relates to a gel electrolyte composition including a first polymeric monomer, a second polymeric monomer, a lithium salt, an initiator, and a solvent;

the first polymeric monomer comprises at least one of methyl methacrylate, styrene, vinyl acetate, acrylonitrile, fluoroacrylate, polyethylene glycol diacrylate (PEGDA), and polyethylene glycol acrylate;

the second polymeric monomer comprises phosphate substances containing carbon-carbon double bonds and/or carbon-nitrogen triple bonds.

The gel electrolyte composition can be used for preparing gel electrolyte with excellent conductivity and flame retardance.

The gel electrolyte composition of the present invention may be prepared by combining any one of the first and second polymeric monomers.

Preferably, the second polymeric monomer comprises at least one of dimethyl vinylphosphonate (DMVP), diethyl vinylphosphonate, diethyl allylphosphonate and dimethyl isopropenylphosphonate.

Preferably, the molar ratio of the first polymerized monomer to the second polymerized monomer is (0.1-30): 1, preferably (0.2-5): 1.

In one embodiment, the molar ratio of the first polymeric monomer to the second polymeric monomer is (0.1 to 90: 1), and may be selected from 0.1:1, 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, or 85: 1.

Preferably, the gel electrolyte composition further includes a plasticizer.

Preferably, the plasticizer comprises at least one of vinylene carbonate, fluoroethylene carbonate, propylene carbonate and triethyl phosphate;

preferably, the mass of the plasticizer is 0.5% to 10% of the mass of the gel electrolyte composition.

The proper amount of the plasticizer can further improve the conductivity of the gel electrolyte.

In one embodiment, the mass of the plasticizer is 0.5% to 10% of the mass of the gel electrolyte composition, and may be selected from 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9%.

Preferably, the initiator includes at least one of Azobisisobutyronitrile (AIBN), azobisisoheptonitrile, dibenzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide.

The invention adopts at least one of the initiators to better promote the polymerization reaction. The invention adopts a proper amount of initiator to control the polymerization reaction in a proper speed range; if the dosage of the initiator is too small, the initiation is not easy, and the reaction can not be carried out; if the initiator is too much, the reaction speed is too fast to be controlled easily.

Preferably, the lithium salt includes lithium hexafluorophosphate (LiPF)₆)。

Preferably, the ratio of the total mass of the first polymerized monomer and the second polymerized monomer to the mass of the solvent is (1-99): 1-99, preferably (2-70): 30-98.

In one embodiment, the ratio of the total mass of the first and second polymeric monomers to the mass of the solvent is (1-99) to (1-99), and may be selected from 1:99, 2:98, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:50, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, or 99: 1.

Preferably, the solvent comprises ethylene carbonate, diethyl carbonate and dimethyl carbonate, and the mass ratio of the ethylene carbonate to the diethyl carbonate to the dimethyl carbonate is (1-4): (1-3): (1-3).

In one embodiment, the mass ratio of ethylene carbonate, diethyl carbonate and dimethyl carbonate may also be selected from 1:1:1, 1:1:2, 1:2:1, 1:2:3, 2:3:1, 2:3:3, 3:1:1, 3:2:1, 4:2:3 or 4:3: 3.

According to another aspect of the present invention, the present invention also relates to a method for preparing the gel electrolyte composition, comprising the steps of:

mixing the above components.

The gel electrolyte composition disclosed by the invention is prepared by uniformly mixing all the components.

According to another aspect of the present invention, the present invention also relates to a method for preparing a gel electrolyte, comprising the steps of:

the gel electrolyte composition is subjected to polymerization reaction under heating.

The preparation method of the gel electrolyte is simple and easy to implement, and the gel electrolyte can be obtained by heating the gel electrolyte composition.

Preferably, the gel electrolyte composition is subjected to the polymerization reaction in a cell or a glass container.

Preferably, the glass container comprises a glass bottle.

In one embodiment, the gel electrolyte composition of the present invention may be placed in a glass container to be subjected to a polymerization reaction under heating to obtain a gel electrolyte.

In one embodiment, the gel electrolyte composition is injected into the battery core for polymerization reaction through a one-step method, and can be directly used in the existing battery production process.

Preferably, the temperature of the polymerization reaction is 50-110 ℃, and preferably 50-80 ℃.

In one embodiment, the polymerization temperature is 50-110 ℃, and can be 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃ or 105 ℃.

Preferably, the time of the polymerization reaction is 1-48 h, preferably 6-24 h.

In one embodiment, the polymerization reaction time is 1 to 48 hours, and 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, or 48 hours can be selected.

According to another aspect of the invention, the invention also relates to the gel electrolyte prepared by the preparation method of the gel electrolyte.

The gel electrolyte of the invention anchors free phosphate or other functional additives in the skeleton of the material, radically solves the leakage problem of the electrolyte and improves the safety performance of the battery.

In one embodiment, the gel electrolyte has a structure according to formula (i);

P-A-A-P-A-P-A-P-A-P-A-A-A-P

(Ⅰ)；

in the formula (I), A is polyethylene glycol diacrylate, and P is vinyl dimethyl phosphate.

The polyethylene glycol diacrylate ester provided by the invention provides a self-supporting polymer skeleton and conductive performance, and the alkenyl dimethyl phosphate provides a flame retardant function. The gel electrolyte FRGPE has a structure shown in a formula (I), wherein PEGDA and DMVP jointly form a polymer structure, on one hand, PEGDA contains a repeating unit structure (-CH2CH2O-) capable of conducting lithium ions, and the dissociation of LiPF6 is facilitated due to the existence of an ester group (COO-); monomers of DMVP contain electronegative functional groups (P ═ O), which is also advantageous for LiPF₆Liberation of more free Li⁺Participating in electric conduction; on the other hand, since two monomers are used for copolymerization, the crystallinity of the resulting material must be smaller than that of the product polymerized from its single components. Lower crystallinity means more amorphous regions, which is also beneficial for the dissociation and conduction of lithium salts.

According to another aspect of the invention, the invention also relates to a lithium ion battery comprising a gel electrolyte as described above.

The flame-retardant gel electrolyte can be directly formed in the battery in one step without changing any process of the existing liquid battery. Meanwhile, the gel battery prepared by the one-step method also solves the solid-solid interface contact problem in the solid electrolyte, and improves the cycle performance of the battery. The use and popularization of the one-step process provide a good design idea for the transition of the liquid battery to the solid battery.

The present invention will be further explained with reference to specific examples.

Example 1

A method of preparing a gel electrolyte comprising the steps of:

(a) mixing EC, EMC and DMC at room temperature, wherein the mass ratio of EC, EMC and DMC is 1:1:1, and adding certain amount of initiators of azobisisobutyronitrile and LiPF₆After completely dissolving, adding a first polymer monomer PEGDA and a second polymer monomer DMVP, wherein the molar ratio of the two monomers is 1:1, uniformly mixing the first polymerized monomer and the second polymerized monomer in a ratio of 35:65 to the total mass of the solvent to obtain a gel electrolyte composition;

(b) putting the gel electrolyte composition obtained in the step (a) into a glass bottle, putting the glass bottle into an oven, and reacting for 10 hours at 80 ℃ to obtain the gel electrolyte.

Example 2

A method of preparing a gel electrolyte comprising the steps of:

(a) mixing the EC, EMC and DMC solvents at room temperature, wherein the mass ratio of EC, EMC and DMC is 2:5:3, and adding certain amounts of initiators of azodiisoheptanonitrile and LiPF₆After the gel electrolyte composition is completely dissolved, adding a first polymer monomer PEGDA and a second polymer monomer DMVP, wherein the molar ratio of the two monomers is 0.5:1, and the ratio of the total mass of the first polymer monomer and the second polymer monomer to the total mass of the solvent is 40:60, and uniformly mixing to obtain the gel electrolyte composition;

(b) putting the gel electrolyte composition obtained in the step (a) into a glass bottle, putting the glass bottle into an oven, and reacting for 6 hours at 65 ℃ to obtain the gel electrolyte.

Example 3

A method of preparing a gel electrolyte comprising the steps of:

(a) mixing the EC, EMC and DMC at room temperature, adding cumene hydroperoxide and LiPF as initiators₆After the solution is completely dissolved, adding a first polymerization monomer PEGDA and a second polymerization monomer DMVP, wherein the molar ratio of the two monomers is 0.2:1, and the total mass of the first polymerization monomer and the second polymerization monomer and the solventThe total mass ratio is 65:35, and the gel electrolyte composition is obtained after uniform mixing;

(b) putting the gel electrolyte composition obtained in the step (a) into a glass bottle, putting the glass bottle into an oven, and reacting for 48 hours at 100 ℃ to obtain the gel electrolyte.

Example 4

A method of preparing a gel electrolyte under the same conditions as in example 1 except that the first polymeric monomer is methyl methacrylate and the second polymeric monomer is DMVP, and the molar ratio of methyl methacrylate to DMVP is 3: 2.

Example 5

A gel electrolyte was prepared as in example 1 except that the first monomer was styrene and the second monomer was DMVP, and the molar ratio of styrene to DMVP was 2: 3.

Example 6

A gel electrolyte was prepared as in example 1 except that the first monomer was acrylonitrile and the second monomer was DMVP, and the molar ratio of acrylonitrile to DMVP was 2: 3.

Example 7

A gel electrolyte was prepared as in example 1 except that the first monomer was fluoroacrylate and the second monomer was DMVP, and the molar ratio of fluoroacrylate to DMVP was 3: 2.

Example 8

A gel electrolyte is prepared by the same method as in example 1 except that the first polymeric monomer is methyl methacrylate, the second polymeric monomer is diethyl allylphosphonate and dimethyl isopropenylphosphonate, and the molar ratio of methyl methacrylate, diethyl allylphosphonate and dimethyl isopropenylphosphonate is 1:0.5: 0.5.

Example 9

A method for preparing a gel electrolyte, wherein the conditions were the same as those of example 2 except that in the step (a), after the addition of the first polymeric monomer and the second polymeric monomer, the plasticizer was added in an amount of 3% by mass based on the mass of the gel electrolyte composition, and the plasticizer was vinylene carbonate and triethyl phosphate in a mass ratio of 1: 1.

Examples of the experiments

1. Fig. 1 is an optical photograph of the gel electrolyte of example 1, having a self-supporting characteristic. Fig. 2 is a burning test picture of the gel electrolyte of example 1, exhibiting non-burning characteristics.

2. FIG. 3 is a room temperature impedance spectrum of the gel electrolyte obtained in example 1; the intersection point of the curve and the X axis is about 53.8 omega, and the room temperature lithium ion conductivity of the material is about 6 multiplied by 10 according to calculation^-2Scm^-1This indicates that the electrolyte prepared by this method has a low interfacial resistance and reduces the "resistance" to lithium ion transport from the electrochemical kinetics point of view.

The conductivity measured in the above manner for the materials obtained in other examples is shown in table 1;

TABLE 1 conductivity test results

Examples	Conductivity (S cm)-1)
		Example 1	6.0×10-3
Example 2	4.0×10-3
		Example 3	3.2×10-3
Example 4	1.8×10-3
		Example 5	1.2×10-3
Example 6	4.5×10-3
		Example 7	3.6×10-3
Example 8	2.7×10-3
		Example 9	4.2×10-3

According to the method, the phosphate substances containing carbon-carbon double bonds and/or carbon-carbon triple bonds are anchored in the polymer skeleton instead of being dissociated in the liquid electrolyte, and the prepared gel electrolyte applied to the battery can greatly reduce the risk of battery leakage. The gel electrolyte synthesized by the method has the characteristics of flame retardance and high conductivity, and the safety performance of the battery is greatly improved.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.