Solid-state battery and its flame-retardant polymer solid-state electrolyte
By leveraging the synergistic effect of halogenated monomers and halogenated esters, a flame-retardant polymer solid electrolyte was prepared, solving the flammability problem of lithium-ion batteries under abuse conditions and improving the safety and electrochemical performance of the batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-09-30
- Publication Date
- 2026-03-27
AI Technical Summary
The electrolyte in existing lithium-ion batteries is flammable under abuse conditions, leading to safety issues, and conventional flame retardants affect conductivity and electrochemical stability.
Flame-retardant polymer solid electrolytes were prepared by cross-linking reaction using the synergistic effect of halogenated monomers and halogenated esters, and a stable electrolyte structure was constructed by combining in-situ cross-linking.
It significantly improves the flame retardant and electrochemical properties of solid electrolytes, and enhances the high-temperature safety and cycle stability of batteries.
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Figure CN115911535B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of solid-state electrolyte lithium secondary batteries, and particularly relates to a lithium solid-state battery and a solid-state electrolyte thereof. BACKGROUND
[0002] The electrolyte is one of the core substances of the lithium ion battery that provides power for electric vehicles, and improves the mobility between the mobile anode and the cathode, playing a role of a medium. As an important component of lithium ion batteries, the electrolyte plays a bridge role in transmitting electric charges between the positive and negative electrodes, and is almost involved in all reaction processes occurring inside the battery. The electrolyte used in the current lithium ion battery is mostly organic system electrolyte. Under the condition of abuse such as overcharge, overdischarge, short circuit and thermal shock, the temperature of the battery rises rapidly, and the electrolyte generally has the problem of flammability, which often leads to the fire of the battery, and even explosion. Generally speaking, when the battery is abused, the temperature inside the battery will rise, and the temperature rise will cause the solid electrolyte film on the surface of the negative electrode to be destroyed, thereby causing a violent chemical reaction between the components in the electrolyte and the negative electrode. The decomposition of the organic solvent in the electrolyte produces hydroxyl radicals and hydrogen radicals, and these radicals will undergo a chain reaction to generate a large amount of heat. The generated heat promotes the reaction between the electrolyte and the lithium-embedded negative electrode, ultimately affecting the safety of the battery. The addition of certain additives to the electrolyte solution can make the flammable electrolyte become difficult or non-flammable, reduce the heat release and self-heat generation rate of the battery, and improve the thermal stability of the electrolyte, thereby avoiding the combustion or explosion of the battery under overheating conditions. At present, the flame retardant additives for lithium ion batteries are mostly organic phosphides, organic halides and phosphorus-halogen, phosphorus-nitrogen composite compounds. The phosphorus-based flame retardant has a certain mutual solubility with non-aqueous medium, but the viscosity of the phosphate-based flame retardant is large, which will reduce the conductivity of the electrolyte, and the electrochemical stability is poor. The halogen-based flame retardant is mainly organic fluorides, including fluorinated carbonates and alkyl perfluoroalkyl ether. Among them, fluorinated cyclic carbonates have good stability, high flash point and dielectric constant, not only have certain flame retardant effect, but also can optimize the properties of SEI film and improve the compatibility of electrolyte and negative electrode material.
[0003] However, ordinary olefinic acid ester polymers are unstable at the interface of the positive electrode or the negative electrode, especially in lithium cobaltate and ternary batteries with a voltage higher than 4.2V. Although the conventional flame retardant improves the room temperature performance of the battery, the melting point and boiling point of the flame retardant will decrease with the introduction of halogenated functional groups, which makes the electrolyte have the disadvantages of easy evaporation and poor high temperature performance. In summary, there is an urgent need in the art to develop a simple and efficient preparation method of flame-retardant in-situ gel electrolyte, and the preparation of solid-state lithium ion batteries with high energy density and cycle stability has always been a hot research topic in the art. SUMMARY
[0004] To solve the defects of the existing solid-state electrolyte, the first object of the present application is to provide a preparation method of a flame-retardant polymer solid-state electrolyte, aiming to prepare a solid-state electrolyte (also referred to as a solid electrolyte, a semi-solid electrolyte or a gel electrolyte) with good flame retardance and electrochemical performance.
[0005] The second object of the present application is to provide a flame-retardant polymer solid-state electrolyte prepared by the preparation method.
[0006] The third object of the present application is to provide a solid-state battery comprising the flame-retardant polymer solid-state electrolyte and a preparation method thereof.
[0007] A preparation method of a flame-retardant polymer solid-state electrolyte, comprising: performing a cross-linking reaction on a raw material solution in which a halogenated monomer, a halogenated acid ester, an initiator, a cross-linking agent and a base electrolyte of formula 1 are dispersed and / or dissolved to obtain a flame-retardant polymer solid-state electrolyte.
[0008]
[0009] Formula 1
[0010] R1, R2, R3 and Y are independently H, alkenyl, alkyl or alkyl with a substituent a, and the substituent a is at least one of aryl, halogen, alkenyl, alkoxy or ester group; wherein at least one of R1, R2, R3 and Y contains halogen; A is O or NR; and R is H or alkyl.
[0011] The halogenated acid ester is at least one of a carboxylic acid ester, a carbonate, a phosphoric acid ester, a phosphite, a pyrophosphoric acid ester, a polyphosphoric acid ester, a nitrogen-substituted phosphoric acid ester and a halogenated phosphoric acid ester containing a halogen substituent.
[0012] The present application researches and finds that the combination of the monomer of formula 1 containing a halogen substituent and the halogenated acid ester can achieve synergy, unexpectedly solve the problem that it is difficult to balance the flame retardance and the electrochemical performance, and significantly improve the flame retardance and the electrochemical performance of the solid-state electrolyte.
[0013] In the present application, the framework construction of the monomer of formula 1 containing a halogen and the chemical action between the halogenated acid ester are the keys to achieve synergy, strengthen the interaction between the polymer framework and other components, strengthen the stability of the solid-state electrolyte, reduce the embedding of the components into the electrode material in the cycle process, and improve the flame retardance and the electrochemical performance of the solid-state electrolyte. It is also found that further controlling the structure of the monomer and the structure and proportion of the halogenated acid ester can help to further improve the chemical action between the components, further improve the stability of the structure, and further improve the flame retardance and the electrochemical performance of the solid-state electrolyte.
[0014] In the present application, in formula 1, the alkyl is, for example, C1-C 12straight or branched chain saturated alkyl group (preferably C1-C6). The alkenyl group is, for example, a vinyl group or an alkenyl group which is mutually conjugated; the unsaturated carbon of the alkenyl group can have a substituent group, such as a C1-C6 alkyl group. The aryl group is, for example, a phenyl group or the like. The alkyl group having a substituent group a is an alkyl group in which any of the H of the alkyl group (for example, C1-C6 alkyl group) is replaced by a substituent group a. The number of the substituent group a is not less than (greater than or equal to) 1 and is less than or equal to a full substitution (the number is 2 * the number of carbons of the alkyl group + 1). In the present application, the formula 1 must have a halogen substituent group, and the halogen substituent group can be located at any of the permissible positions in the formula 1. In the present application, A can be O, that is, the formula 1 is a halogen-containing acrylate monomer. A can also be NR, that is, the formula 1 monomer is a halogen-containing acrylamide internal monomer. 12 The alkenyl group is, for example, a vinyl group or an alkenyl group which is mutually conjugated; the unsaturated carbon of the alkenyl group can have a substituent group, such as a C1-C6 alkyl group. The aryl group is, for example, a phenyl group or the like. The alkyl group having a substituent group a is an alkyl group in which any of the H of the alkyl group (for example, C1-C6 alkyl group) is replaced by a substituent group a. The number of the substituent group a is not less than (greater than or equal to) 1 and is less than or equal to a full substitution (the number is 2 * the number of carbons of the alkyl group + 1). In the present application, the formula 1 must have a halogen substituent group, and the halogen substituent group can be located at any of the permissible positions in the formula 1. In the present application, A can be O, that is, the formula 1 is a halogen-containing acrylate monomer. A can also be NR, that is, the formula 1 monomer is a halogen-containing acrylamide internal monomer.
[0015] As a preference, in the formula 1, R1, R2, R3 are independently H, C1-C6 alkyl group, or halogen-substituted C1-C6 alkyl group;
[0016] As a preference, in the formula 1, A is O;
[0017] As a preference, in the formula 1, Y is an alkyl group having a substituent group a, and the substituent group a contains at least a halogen;
[0018] As a preference, in the formula 1, the halogen is at least one of F, Cl, Br; further preferably F.
[0019] Further preferably, the halogenated monomer is at least one compound having the formula 1-A structure:
[0020]
[0021] In the formula 1-A, R1 is H or C1-C3 alkyl group; Y is a C1-C3 alkyl group having a halogen; preferably, the halogen is F or Cl; the number of the halogen is not less than 1; preferably not less than 2.
[0022] Further preferably, the halogenated monomer is two or more compounds having the formula 1-A structure, particularly preferably a mixed monomer of the formula 1-A compounds in which Y is a fluorine-substituted alkyl group and a chlorine-substituted alkyl group.
[0023] More preferably, the halogenated monomers include halogenated monomer a and halogenated monomer b, wherein halogenated monomer a is a compound of formula 1-A in which Y is substituted with 2 or more (preferably 4-6) fluorine; and halogenated monomer b is a compound of formula 1-A in which Y is substituted with 2 or more (preferably 2-3) chlorine. Preferably, the molar content of one of the mixed monomers is 20-60%, and the rest is other components.
[0024] The present application also found that further controlling the halogen and halogen content in the monomer of formula 1 helps to further improve the chemical action of the polymer framework and other components, and helps to further improve the stability of the solid-state electrolyte, improve the flame retardancy and stability of the solid-state electrolyte.
[0025] Preferably, the content of halogen in the halogenated monomer is greater than or equal to 7atm%.
[0026] In the present application, the combination of halogen-containing monomers and halogen-containing acid esters is the key to improving the flame retardancy and electrochemical performance of the solid-state electrolyte. In the present application, the halogenated acid ester can be a compound with halogen and having at least one structural fragment of formula 1-A.
[0027] Preferably, the halogenated acid ester is a compound having at least one of the following structural formulas:
[0028]
[0029]
[0030]
[0031] R4 and R5 are independently alkyl, alkyl containing substituent b; A1, A2 and A3 are independently H, alkyl, alkoxy, halogen, alkyl containing substituent b or alkoxy containing substituent b; and substituent b is at least one of aryl, halogen, alkenyl, alkoxy or ester group;
[0032] At least one of A1, A2, A3 and R4 contains halogen.
[0033] X is halogen.
[0034] In the present application, the alkyl in formula 2-A-C is, for example, a straight-chain or branched-chain saturated alkane of C1-C 12 The alkyl containing substituent b is alkyl (for example C1-C 12 , preferably alkyl in which any of the C-H groups in C1-C6 is replaced by a substituent b. The number of said substituent b is not less than (greater than or equal to) 1 and less than or equal to full substitution (the number is 2*the number of carbon atoms in the alkyl group+1). In the present application, the halogen substituent in formula 2-A-C must be present, and the halogen substituent can be located at any of the allowable positions in formula 2-A-C.
[0035] Further preferably, the halogenated acid ester is a compound of the following structural formula:
[0036]
[0037]
[0038] R6 is C1-C4 alkyl with a halogen substituent, wherein the number of halogens is not less than 1, preferably not less than 2; further preferably 2-3;
[0039] Said R4, R5 are independently C1-C4 alkyl.
[0040] Further preferably, the halogenated acid ester is a mixture of two or more compounds of formula 2-A-1, and particularly preferably is a mixed halogenated acid ester of 2-A-1 compounds in which R6 is an alkyl group substituted with fluorine and an alkyl group substituted with chlorine.
[0041] More preferably, the halogenated acid ester is a mixed halogenated acid ester of halogenated acid ester A and halogenated acid ester B, wherein the halogenated acid ester A is a compound of formula 2-A-1 in which R6 is a C1-C3 alkyl group substituted with 2 or more (preferably 2-4) fluorines; and the halogenated acid ester B is a compound of formula 2-A-1 in which R6 is a C1-C3 alkyl group substituted with 2 or more (preferably 2-3) chlorines.
[0042] When it is a mixed halogenated acid ester, the molar content of one is 20-60%, and the balance is the other component. For example, the content of halogenated acid ester A is 20-60%, and the balance is halogenated acid ester B.
[0043] Further research in the present application has found that the halogens in the halogen monomer and the halogenated acid ester are selected from the same element, preferably F, which can further improve the synergy and further improve the flame retardance and cycle stability of the solid-state electrolyte.
[0044] In the present application, the crosslinking agent, initiator and base electrolyte can all be conventional components in the industry.
[0045] For example, the crosslinking agent is one or more of methyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, pentaerythritol tetraacrylate, and bistrishydroxymethylpropane tetraacrylate.
[0046] Preferably, the initiator is an initiator capable of initiating polymerization of the halogen monomer, and is further preferably at least one of azobisisobutyronitrile, dibenzoyl peroxide;
[0047] Preferably, the base electrolyte comprises a conductive lithium salt and an organic solvent dissolving the conductive lithium salt;
[0048] Preferably, the conductive lithium salt is one or a mixture of more than one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisdifluorosulfonylimide, lithium bis-trifluoromethylsulfonylimide, lithium bisoxalate borate, lithium difluoro oxalate borate; and the organic solvent is one or a mixture of more than one of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate;
[0049] Preferably, the base electrolyte further comprises a functional additive, and preferably the functional additive is at least one of vinylene carbonate, fluorobenzene, adiponitrile;
[0050] Preferably, in the base electrolyte, the concentration of the conductive lithium salt is 0.7-2M;
[0051] Preferably, in the base electrolyte, the functional additive is added in an amount of 1-10% in the base electrolyte.
[0052] Preferably, in the starting raw material solution, the halogen monomer is 2-70wt% of the base electrolyte, and preferably 2-20wt%;
[0053] The halogen acid ester is 5-75wt% of the base electrolyte, and preferably 20-70wt%;
[0054] The crosslinking agent and the initiator are respectively 2-5% of the mass of the halogen monomer;
[0055] Preferably, the crosslinking reaction is carried out under heat treatment;
[0056] Preferably, the temperature of the heat treatment is 40-90℃.
[0057] The preparation method of the preferred solid-state electrolyte of the present application comprises the following steps:
[0058] (1) mixing the halogen acid ester and the base electrolyte to obtain solution A:
[0059] (2) then adding the halogen monomer, the crosslinking agent, and the monomer initiator into solution A and stirring to obtain mixture B (raw material solution); heating the mixture B to obtain the flame-retardant gel electrolyte.
[0060] The present application further provides the flame-retardant polymer solid-state electrolyte prepared by the preparation method.
[0061] The application also provides a solid-state lithium secondary battery, comprising a positive electrode, a separator and a negative electrode which are sequentially compounded, and the flame-retardant polymer solid-state electrolyte prepared by the preparation method.
[0062] The positive electrode, the separator and the negative electrode of the solid-state secondary battery can be known in the lithium battery field. For example, the positive electrode comprises a current collector and a positive electrode material compounded on the surface of the current collector, and the positive electrode material can comprise a positive electrode active material, a conductive agent and a binder. The negative electrode can comprise a current collector and a negative electrode material compounded on the surface of the current collector, and the negative electrode material can comprise a negative electrode active material, a conductive agent and a binder. The current collector, the negative electrode active material, the positive electrode active material, the conductive agent and the binder of the application can be known ingredients in the industry.
[0063] The application also provides a preparation method of the solid-state lithium secondary battery. The positive electrode, the separator and the negative electrode are sequentially compounded to form an electrode core, the electrode core is placed in a battery cell shell, the raw material solution is injected into the battery cell shell by using the preparation method, and in-situ crosslinking reaction is performed to form the solid-state electrolyte in-situ, thereby obtaining the solid-state lithium secondary battery.
[0064] The application researches and finds that, by the synergistic components and the in-situ crosslinking method, the solid-state electrolyte with complete structure and flame-retardant effect can be successfully constructed in the battery, and the electrochemical performance and safety of the obtained solid-state battery can be effectively improved.
[0065] The preferred preparation method of the solid-state battery of the application comprises the following steps:
[0066] (1) preparing a positive electrode sheet and a negative electrode sheet; the positive electrode sheet, the negative electrode sheet and the separator are prepared into an electrode core in a winding manner and placed in an aluminum plastic film.
[0067] (2) injecting the mixed solution B into the electrode core in (1), vacuum sealing the electrode core, standing at room temperature, and then performing in-situ thermal polymerization reaction at a temperature of 40-90 DEG C for 8-24 hours to obtain a lithium ion battery filled with a flame-retardant gel electrolyte.
[0068] The application has the following beneficial effects:
[0069] (1) The mutual cooperation of the halogenated monomer and the halogenated acid ester can realize synergy, improve the chemical combination between the components, improve the stability of the solid-state electrolyte, and improve the flame-retardant and electrochemical performance thereof.
[0070] (2) Further control of the structure, composition and proportion of the halogenated monomer and halogenated acid ester helps to further improve the synergy, further improve the flame retardation and electrochemical performance;
[0071] (3) The polymer skeleton described in the present application has a high degree of carbonylation, which can interact with the carbonyl in the electrolyte, absorb more electrolyte, reduce the volatilization of the electrolyte solvent at high temperature, and thus improve the high temperature performance of the battery. BRIEF DESCRIPTION OF DRAWINGS
[0072] Figure 1 is the SEM image of the base separator in Example 1;
[0073] Figure 2 is the SEM image of the composite electrolyte film obtained in Example 1;
[0074] Figure 3 is the constant current charge-discharge performance diagram of the lithium ion battery obtained in Example 1;
[0075] Figure 4 is the state of the gel under flame obtained in Example 1;
[0076] Figure 5 is the constant current charge-discharge performance diagram of the lithium ion battery obtained in Comparative Example 1. DETAILED DESCRIPTION
[0077] The following examples are intended to further illustrate the present application and are not intended to limit the scope of the claims.
[0078] Example 1:
[0079] Step (1): Preparation of raw material solution:
[0080] In this case, the structure of the halogenated acid ester is:
[0081] The structure of the halogenated monomer is:
[0082] The base electrolyte is: propylene carbonate as the solvent, lithium hexafluorophosphate as the conductive lithium salt, and chlorobenzene as the additive, mixed to obtain the base electrolyte, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0083] The halogenated acid ester, the halogenated monomer, a crosslinking agent (pentaerythritol tetraacrylate), and an initiator (azobisisobutyronitrile) are mixed in the base electrolyte to obtain a raw material solution. In the raw material solution, the halogenated acid ester is added in an amount of 75% (mass, the corresponding proportions below are also mass ratios) relative to the base electrolyte; the halogenated monomer is added in an amount of 2% (mass, the corresponding proportions below are also mass ratios) relative to the base electrolyte; the crosslinking agent is the same mass as the halogenated monomer; and the initiator is 2% of the mass of the halogenated monomer.
[0084] Step (2): Crosslinking
[0085] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF in a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, and after the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12 h, and then heated at 60°C for 6 h. Figure 1 is a SEM image of the original separator, Figure 2 is a SEM image of the separator after gelation by heating, as shown, the polymer skeleton is uniformly distributed on the separator, and the original porous structure of the separator disappears.
[0086] Figure 3 It is shown that the full battery prepared by the method has a specific capacity of 118 mAh / g after 500 cycles at room temperature when the positive electrode material is discharged at a constant current of 1C, showing good cycle performance. The gel prepared by the method is placed in a flame, as shown in Figure 4 , and cannot be burned for a period of time in the flame.
[0087] Example 2:
[0088] Compared with Example 1, the main difference is that the halogenated monomer is changed, specifically:
[0089] Step (1): Preparation of raw material solution:
[0090] In this case, the structure of the halogenated acid ester is:
[0091] The structure of the halogenated monomer is:
[0092] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0093] The halogenated acid ester, the halogenated monomer, a crosslinking agent (pentaerythritol tetraacrylate), and an initiator (azobisisobutyronitrile) are added to the base electrolyte solution to obtain a raw material solution. In the raw material solution, the halogenated acid ester is added in an amount of 75% relative to the base electrolyte solution; the halogenated monomer is added in an amount of 2% relative to the base electrolyte solution; the crosslinking agent is the same mass as the halogenated monomer; and the initiator is 2% of the mass of the halogenated monomer.
[0094] Step (2): Crosslinking
[0095] LiFeP04is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 115 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0096] Example 3:
[0097] Compared with Example 1, the only difference is that the halogenated monomer is changed, specifically:
[0098] Step (1): Preparation of raw material solution:
[0099] In this case, the structure of the halogenated acid ester is:
[0100] The structure of the halogenated monomer is:
[0101] The base electrolyte solution is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0102] The halogenated acid ester, the halogenated monomer, a crosslinking agent (pentaerythritol tetraacrylate), and an initiator (azobisisobutyronitrile) are added to the base electrolyte solution to obtain a raw material solution. In the raw material solution, the halogenated acid ester is added in an amount of 75% relative to the base electrolyte solution; the halogenated monomer is added in an amount of 2% relative to the base electrolyte solution; the crosslinking agent is the same mass as the halogenated monomer; and the initiator is 2% of the mass of the halogenated monomer;
[0103] Step (2): Crosslinking
[0104] LiFePO4 is selected as the positive active material, which is coated into positive electrode sheet with Super-P, PVDF according to the ratio of 8:1:1, dried and used. The prepared electrode is matched with polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, and after the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12 h, and then heated at 60℃ for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity can still be maintained at 120 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method is placed in the flame and cannot be burned.
[0105] Example 4:
[0106] Compared with Example 3, the only difference is that the halogenated acid ester is changed, specifically:
[0107] Step (1): Preparation of raw material solution:
[0108] In this case, the structure of the halogenated acid ester is:
[0109] The structure of the halogenated monomer is:
[0110] The basic electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0111] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator (azobisisobutyronitrile) are added to the basic electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the basic electrolyte is 75%; the addition amount of the halogenated monomer relative to the basic electrolyte is 2%; the mass of the crosslinking agent is the same as that of the halogenated monomer; and the amount of the initiator is 2% of the mass of the halogenated monomer.
[0112] Step (2): Crosslinking
[0113] LiFePO4 is selected as the positive active material, which is coated into positive electrode sheet with Super-P, PVDF according to the ratio of 8:1:1, dried and used. The prepared electrode is matched with polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, and after the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12 h, and then heated at 60℃ for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity can still be maintained at 126 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method is placed in the flame and cannot be burned.
[0114] Example 5:
[0115] The difference compared with Example 4 is mainly that the halogenated acid ester is changed, specifically:
[0116] Step (1): Preparation of raw material solution
[0117] In this case, the structure of the halogenated acid ester is:
[0118] The structure of the halogenated monomer is:
[0119] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0120] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator (azobisisobutyronitrile) are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 75%; the addition amount of the halogenated monomer relative to the base electrolyte is 2%; the mass of the crosslinking agent is the same as that of the halogenated monomer; and the amount of the initiator is 2% of the mass of the halogenated monomer.
[0121] Step (2): Crosslinking
[0122] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF in a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, and after the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 117mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0123] Example 6
[0124] The difference compared with Example 4 is mainly that the halogenated acid ester is changed, specifically:
[0125] Step (1): Preparation of raw material solution
[0126] In this case, the structure of the halogenated acid ester is:
[0127] The structure of the halogenated monomer is:
[0128] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0129] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 75%, the addition amount of the halogenated monomer relative to the base electrolyte is 2%, the mass of the crosslinking agent is the same as that of the halogenated monomer, and the initiator is 2% of the mass of the halogenated monomer.
[0130] Step (2): Crosslinking
[0131] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 127mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0132] Example 7:
[0133] Compared with Example 6, the only difference is that the halogenated monomer is changed, specifically:
[0134] Step (1): Preparation of raw material solution:
[0135] In this case, the structure of the halogenated acid ester is:
[0136] The structure of the halogenated monomer is:
[0137] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0138] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 75%, the addition amount of the halogenated monomer relative to the base electrolyte is 2%, the mass of the crosslinking agent is the same as that of the halogenated monomer, and the initiator is 2% of the mass of the halogenated monomer.
[0139] Step (2): Cross-linking
[0140] LiFePO4 was selected as the positive active material, which was coated with Super-P, PVDF in the ratio of 8:1:1 to form a positive electrode sheet, which was dried and used. The prepared electrode was matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After completing the packaging of the 2025 button cell, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity can still be maintained at 130 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0141] Example 8:
[0142] Compared with Example 7, the only difference is that the monomer content is adjusted, specifically:
[0143] Step (1): Preparation of raw material solution:
[0144] In this case, the structure of the halogenated acid ester is:
[0145] The structure of the halogenated monomer is:
[0146] The basic electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive. The concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0147] The halogenated acid ester, the halogenated monomer, the cross-linking agent (ethylene glycol dimethyl methacrylate), and the initiator (azobisisobutyronitrile) are added to the basic electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the basic electrolyte is 22.5%; the addition amount of the halogenated monomer relative to the basic electrolyte is 70%; the mass of the cross-linking agent is the same as that of the halogenated monomer; and the mass of the initiator is 2% of the mass of the halogenated monomer.
[0148] Step (2): Cross-linking
[0149] LiFePO4 was selected as the positive active material, which was coated with Super-P, PVDF in the ratio of 8:1:1 to form a positive electrode sheet, which was dried and used. The prepared electrode was matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After completing the packaging of the 2025 button cell, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity can still be maintained at 130 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0150] Example 9:
[0151] Compared with Example 7, the difference is only in the regulation of monomer and flame retardant content, specifically:
[0152] Step (1): raw material solution preparation:
[0153] In this case, the structure of the halogenated acid ester is:
[0154] The structure of the halogenated monomer is:
[0155] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0156] The halogenated acid ester, the halogenated monomer, the crosslinking agent (ethylene glycol dimethyl methacrylate), and the initiator (azobisisobutyronitrile) are mixed in the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 40%; the addition amount of the halogenated monomer relative to the base electrolyte is 50%; the mass of the crosslinking agent is the same as that of the halogenated monomer; and the amount of the initiator is 2% of the mass of the halogenated monomer;
[0157] Step (2): crosslinking
[0158] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet with Super-P and PVDF in a ratio of 8:1:1, and is dried for use. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 120mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0159] Example 10:
[0160] Compared with Example 7, the difference is only in the regulation of monomer species, which is a mixture of two kinds of halogenated monomers, specifically:
[0161] Step (1): raw material solution preparation:
[0162] In this case, the structure of the halogenated acid ester is:
[0163] The structure of the halogenated monomer is: The molar ratio is 1:1;
[0164] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0165] The halogenated acid ester, the halogenated monomer, the crosslinking agent (ethylene glycol dimethyl methacrylate), and the initiator (azobisisobutyronitrile) are mixed in the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 22.5%; the total addition amount of the halogenated monomer relative to the base electrolyte is 70%, and the mass ratio is 1:1; the mass of the crosslinking agent is the same as that of the total halogenated monomer; and the mass of the initiator is 2% of the total halogenated monomer.
[0166] Step (2): crosslinking
[0167] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, a 2025 button cell is packaged, and the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 133mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0168] Example 11:
[0169] Compared with Example 7, the only difference is that the type of flame retardant is two kinds of halogenated acid esters mixed, specifically:
[0170] Step (1): preparation of raw material solution:
[0171] In this case, the structure of the halogenated acid ester is: The molar ratio is 1:1.
[0172] The structure of the halogenated monomer is:
[0173] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0174] The halogenated acid ester, the halogenated monomer, a crosslinking agent (ethylene glycol dimethyl methacrylate), and an initiator (azobisisobutyronitrile) are added to the base electrolyte solution to obtain a raw material solution. In the raw material solution, the total halogenated acid ester is added in an amount of 22.5% relative to the base electrolyte solution, and the mass ratio is 1:1; the halogenated monomer is added in an amount of 70% relative to the base electrolyte solution; the crosslinking agent has the same mass as the halogenated monomer; and the initiator is 2% of the mass of the halogenated monomer.
[0175] Step (2): Crosslinking
[0176] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity can still be maintained at 128 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method cannot be burned when placed in a flame.
[0177] Example 12:
[0178] Compared with Example 10, the only difference is that the type of flame retardant is two halogenated acid esters mixed, and the specific type is:
[0179] Step (1): Preparation of raw material solution:
[0180] In this case, the structure of the halogenated acid ester is: The molar ratio is 1:1:
[0181] The structure of the halogenated monomer is: The molar ratio is 1:1:
[0182] The base electrolyte solution is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0183] The halogenated acid ester, the halogenated monomer, a crosslinking agent (ethylene glycol dimethyl methacrylate), and an initiator (azobisisobutyronitrile) are added to the base electrolyte solution to obtain a raw material solution. In the raw material solution, the total halogenated acid ester is added in an amount of 22.5% relative to the base electrolyte solution, and the mass ratio is 1:1; the total halogenated monomer is added in an amount of 70% relative to the base electrolyte solution, and the mass ratio is 1:1; the crosslinking agent has the same mass as the total halogenated monomer; and the initiator is 2% of the mass of the total halogenated monomer.
[0184] Step (2): Crosslinking
[0185] LiFePO4 was selected as the positive active material, which was coated with Super-P, PVDF in a ratio of 8:1:1 to form a positive electrode sheet, and dried for use. The prepared electrode was matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After completing the packaging of the 2025 button cell, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity could still be maintained at 138 mAh / g after 500 cycles, showing good cycle performance. The gel prepared by this method was placed in a flame, and could not be burned.
[0186] Comparative Example 1:
[0187] Compared with Example 7, the only difference is that a polymer monomer without halogen is selected, which is:
[0188] Step (1): Preparation of raw material solution:
[0189] In this case, the structure of the halogenated acid ester is:
[0190] The structure of the monomer is:
[0191] The basic electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0192] The halogenated acid ester, the monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the basic electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the basic electrolyte is 75%; the addition amount of the monomer relative to the basic electrolyte is 2%; the mass of the crosslinking agent is the same as that of the monomer; and the mass of the initiator is 2% of the mass of the monomer.
[0193] Step (2): Crosslinking
[0194] LiFePO4 was selected as the positive active material, which was coated with Super-P, PVDF in a ratio of 8:1:1 to form a positive electrode sheet, and dried for use. The prepared electrode was matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After completing the packaging of the 2025 button cell, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. As shown in Figure 5 , when discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity was only 50 mAh / g after 500 cycles, and the cycle performance was poor. The gel prepared by this method was placed in a flame, and could not be burned.
[0195] Comparative Example 2:
[0196] Compared with Example 7, the only difference is that the amount of the halogenated acid ester is adjusted, specifically:
[0197] Step (1): Preparation of raw material solution:
[0198] In this case, the structure of the halogenated acid ester is:
[0199] The structure of the halogenated monomer is:
[0200] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0201] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the amount of the halogenated acid ester added relative to the base electrolyte is 80%; the amount of the halogenated monomer added relative to the base electrolyte is 2%; the mass of the crosslinking agent is the same as that of the halogenated monomer; and the amount of the initiator is 2% of the mass of the halogenated monomer.
[0202] Step (2): Crosslinking
[0203] LiFePO4 is selected as the positive active material, which is coated with Super-P, PVDF in a ratio of 8:1:1 to form a positive electrode sheet, which is dried and used. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity is only 30mAh / g after 100 cycles, and the cycle performance is poor. The gel prepared by this method cannot be burned when placed in a flame.
[0204] Comparative Example 3:
[0205] Compared with Example 7, the only difference is that the amount of the halogenated acid ester is adjusted, specifically:
[0206] Step (1): Preparation of raw material solution:
[0207] In this case, the structure of the halogenated acid ester is:
[0208] The structure of the halogenated monomer is:
[0209] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0210] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 4%, the addition amount of the halogenated monomer relative to the base electrolyte is 2%, the mass of the crosslinking agent is the same as that of the halogenated monomer, and the initiator is 2% of the mass of the halogenated monomer.
[0211] Step (2): crosslinking
[0212] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, and the raw material solution obtained in step 1 is injected. After the 2025 button cell is packaged, the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity is only 103mAh / g after 500 cycles, and the cycle performance is poor. The gel prepared by this method can be burned when placed in a flame.
[0213] Comparative Example 4:
[0214] Compared with Example 8, the only difference is that the content of the monomer is adjusted, specifically:
[0215] Step (1): preparation of a raw material solution:
[0216] In this case, the structure of the halogenated acid ester is:
[0217] The structure of the halogenated monomer is:
[0218] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0219] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are added to the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 4%, the addition amount of the halogenated monomer relative to the base electrolyte is 2%, the mass of the crosslinking agent is the same as that of the halogenated monomer, and the initiator is 2% of the mass of the halogenated monomer.
[0220] Step (2): crosslinking
[0221] LiFePO4 was selected as the positive active material, which was coated into positive electrode sheet with Super-P, PVDF according to the ratio of 8:1:1, and dried for use. The prepared electrode was matched with polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After the 2025 button cell was packaged, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity remained only 87 mAh / g after 500 cycles, and the cycle performance was poor. The gel prepared by this method was placed in the flame and could not be burned.
[0222] Comparative Example 5:
[0223] Compared with Example 7, the only difference is that no monomer is contained, and only a liquid flame-retardant part is used, which is specifically:
[0224] Step (1): Preparation of raw material solution:
[0225] In this case, the structure of the halogenated acid ester is:
[0226] The basic electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive in the system, wherein the concentration of lithium hexafluorophosphate is 1M; the content of chlorobenzene is 2wt%.
[0227] The halogenated acid ester is added to the basic electrolyte to obtain the raw material solution. In the raw material solution, the content of the halogenated acid ester is 75%
[0228] Step (2): Crosslinking
[0229] LiFePO4 was selected as the positive active material, which was coated into positive electrode sheet with Super-P, PVDF according to the ratio of 8:1:1, and dried for use. The prepared electrode was matched with polypropylene separator and metal lithium, and the raw material solution obtained in step 1 was injected. After the 2025 button cell was packaged, the obtained battery was placed at room temperature for 12 h, and then heated at 60°C for 6 h. When discharged at 1C constant current of the positive electrode material at room temperature, the specific capacity remained only 36 mAh / g after 500 cycles, and the cycle performance was poor. The gel prepared by this method was placed in the flame and could not be burned.
[0230] Comparative Example 6:
[0231] Compared with Example 7, the only difference is that a non-halogenated acid ester is used, which is specifically:
[0232] Step (1): Preparation of raw material solution:
[0233] In this case, the structure of the halogenated acid ester is:
[0234] The structure of the halogenated monomer is:
[0235] The base electrolyte is a solution in which propylene carbonate is used as a solvent, lithium hexafluorophosphate is used as a conductive lithium salt, and chlorobenzene is added as an additive, wherein the concentration of lithium hexafluorophosphate is 1M, and the content of chlorobenzene is 2wt%.
[0236] The halogenated acid ester, the halogenated monomer, the crosslinking agent (pentaerythritol tetraacrylate), and the initiator are mixed in the base electrolyte to obtain a raw material solution. In the raw material solution, the addition amount of the halogenated acid ester relative to the base electrolyte is 75%, the addition amount of the halogenated monomer relative to the base electrolyte is 2%, the mass of the crosslinking agent (azobisisobutyronitrile) is the same as that of the halogenated monomer, and the initiator is 2% of the mass of the halogenated monomer.
[0237] Step (2): Crosslinking
[0238] LiFePO4 is selected as the positive active material, which is coated into a positive electrode sheet together with Super-P and PVDF at a ratio of 8:1:1, dried, and used. The prepared electrode is matched with a polypropylene separator and metal lithium, the raw material solution obtained in step 1 is injected, a 2025 button cell is packaged, and the obtained battery is placed at room temperature for 12h, and then heated at 60℃ for 6h. When discharged at 1C of the positive electrode material at room temperature, the specific capacity is only 82mAh / g after 500 cycles, and the cycle performance is poor. The gel prepared by this method cannot be burned when placed in a flame.
Claims
1. A method for preparing a flame-retardant polymer solid electrolyte, characterized in that, It is obtained by crosslinking a feed solution containing a halogenated monomer of formula 1-A, a halogenated ester, an initiator, a crosslinking agent, and a base electrolyte. The halogenated monomer is at least one compound having the structural formula 1-A: Formula 1-A In Formula 1-A, R1 is H or a C1-C3 alkyl group; Y is a C1-C3 alkyl group containing a halogen; the halogen is F or Cl; and the number of halogens is not less than 2. The haloester is a compound with the structural formula 2-A-1: Formula 2-A-1 R6 is a C1-C4 alkyl group with halogen substituents, wherein the number of halogens is not less than 2; R4 is a C1-C4 alkyl group; In the initial feed solution, the halogenated monomer constitutes 2–70 wt% of the weight of the base electrolyte. The haloester content is 5 to 75 wt% of the weight of the base electrolyte. The crosslinking agent and initiator are 2-5% of the mass of the halogenated monomer, respectively.
2. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, The halogenated monomers include halogenated monomer a and halogenated monomer b, wherein halogenated monomer a is a compound in Formula 1-A in which Y has two or more fluorine substitutions; and halogenated monomer b is a compound in Formula 1-A in which Y has two or more chlorine substitutions.
3. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 2, characterized in that, In a mixture of monomers, one monomer has a molar content of 20-60%, with the remainder being other components.
4. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, In Equation 2-A-1, the number of halogens in R6 is 2 to 3.
5. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, In the halogenated monomer, the content of the halogen is greater than or equal to 7 atm.
6. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, The halogen element in halogenated monomers and halogenated esters is the same, which is F.
7. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, The haloester is a mixed haloester of haloester A and haloester B, wherein haloester A is a compound of formula 2-A-1 in which R6 is a C1-C3 alkyl group with two or more fluorine substitutions; and haloester B is a compound of formula 2-A-1 in which R6 is a C1-C3 alkyl group with two or more chlorine substitutions.
8. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 7, characterized in that, In mixed haloesters, one of them has a molar content of 20-60%, with the remainder being other components.
9. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 1, characterized in that, The crosslinking agent is one or more of methyl methacrylate, ethylene glycol diacrylate, ethylene glycol diacrylate, pentaerythritol tetraacrylate, and bis(trimethylolpropane) tetraacrylate. The initiator is an initiator capable of initiating the polymerization of halogen monomers, and it is at least one of azobisisobutyronitrile and benzoyl peroxide; The basic electrolyte includes a conductive lithium salt and an organic solvent for dissolving the conductive lithium salt. The conductive lithium salt is one or a mixture of more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(difluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalateborate), and lithium difluorooxalateborate; the organic solvent is one or a mixture of more of propylene carbonate, ethylene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. The basic electrolyte also contains functional additives, wherein the functional additives are at least one of vinylene carbonate, fluorobenzene, and adiponitrile. In the basic electrolyte, the concentration of conductive lithium salt is 0.7~2 M; In the base electrolyte, the functional additive is added at a concentration of 1-10%.
10. The method for preparing the flame-retardant polymer solid electrolyte according to any one of claims 1 to 9, characterized in that, Crosslinking reaction is carried out under heat treatment.
11. The method for preparing the flame-retardant polymer solid electrolyte as described in claim 10, characterized in that, The heat treatment temperature is 40℃-90℃.
12. A flame-retardant polymer solid electrolyte prepared by the preparation method according to any one of claims 1 to 11.
13. A solid-state lithium secondary battery, characterized in that, The flame-retardant polymer solid electrolyte comprises a positive electrode, a separator, and a negative electrode sequentially compounded, and is compounded between the positive electrode, the separator, and the negative electrode.
14. The method for preparing a solid-state lithium secondary battery as described in claim 13, characterized in that, A positive electrode, a separator, and a negative electrode are sequentially composited to form a battery cell. The battery cell is placed inside a battery cell housing. Using the preparation method described in any one of claims 1 to 11, the raw material solution is injected into the battery cell housing, and an in-situ crosslinking reaction is carried out to form the solid electrolyte in situ, thereby obtaining the solid lithium secondary battery.
Citation Information
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