Polyionic liquid gel electrolyte and application thereof

Abstract

The application provides a kind of polyionic liquid gel electrolyte and its application, the precursor solution of the polyionic liquid gel electrolyte includes the following components according to weight percentage: N + Cationic center polyionic liquid monomer 30%-90%; Ionic liquid plasticizer 10%-70%; Lithium salt A 10%-80%. The polyionic liquid gel electrolyte provided by the application is combined with the solid-state porous positive electrode prepared by coating the organic-inorganic composite solid-state electrolyte, which constructs a continuous and stable ion transmission channel from the electrode interior to the electrolyte body, and is expected to effectively improve the electrochemical performance and energy density of the solid-state lithium battery while ensuring intrinsic high safety and thermal stability.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology and relates to a polyionic liquid gel electrolyte and its application. Background Technology

[0002] With the diversification of application scenarios, the market has placed higher demands on the energy density and safety of lithium batteries. Traditional liquid electrolytes typically contain low-flash-point organic solvents, which are prone to thermal runaway under abuse or extreme conditions, posing a risk of violent combustion or even explosion. Inorganic solid-state electrolytes are considered to have significantly improved safety due to their inherent non-flammability, but achieving uniform and continuous solid-solid contact at the electrode / electrolyte interface is difficult under limited stacking pressure. Polymer electrolytes, on the other hand, are considered an important option for improving the electrode / electrolyte interface contact in solid-state batteries due to their mechanical toughness.

[0003] Traditional polymer electrolyte matrices, such as PEO (polyethylene oxide), suffer from insufficient high-temperature stability. In contrast, polyionic liquids composed of anions and cations combine the advantages of polymers (easy processing and good mechanical toughness) with the non-volatile and high-temperature resistance of ionic liquids. Polymer solid electrolytes, however, rely excessively on polymer chain segment movement to achieve Li... + Transport, therefore, typically suffers from low ionic conductivity at room temperature (< 10). -4 S cm -1 This makes it difficult to directly apply in lithium batteries. By introducing small liquid molecules to form a polymer gel electrolyte, it is possible to address the issue of Li... + By regulating the solvation structure, it is decoupled from the jumping transport between polymer chain segments, thereby achieving efficient and rapid ion migration.

[0004] Currently, researchers have proposed a wealth of design strategies and optimization routes in the field of polymer gel electrolytes. For example, CN121983660A discloses a high-cycle-stability in-situ cured gel polymer electrolyte, which includes an electrolyte, a main crosslinking agent N,N'-methylenebisacrylamide, and a multi-arm crosslinking agent, achieving stable cycling of lithium-ion batteries for 500 cycles at 25°C and 1C. However, due to the abundance of crosslinking agents, the three-dimensional network structure formed by this gel electrolyte, while improving mechanical stability, can adversely affect the movement of polymer chain segments. Another example is CN121748514A, which discloses a wide-temperature-range gel polymer electrolyte, which includes ethylene carbonate, a eutectic agent, lithium difluorooxalate borate, and a polymer gelling agent, achieving 7×10⁻⁶ cycles. -4 S / cm ~ 9×10 -2It boasts a room-temperature ionic conductivity of S / cm and an operating temperature range of -50 to 190°C, but the 10-80% carbonate-based organic solvents it contains make it difficult to meet the thermal weight loss requirements of all-solid-state battery standards. For example, CN120657242A discloses a flame-retardant, high-ionic-conductivity gel electrolyte containing organic solvents, lithium salts, additives, monomers, crosslinking agents, initiators, and reactive flame retardants. It combines high ionic conductivity, mechanical strength, and flame retardancy, but the unsaturated phosphorus compounds used as flame retardants suffer from insufficient electrochemical stability, easily undergoing reduction on the lithium metal anode side and potentially oxidizing and decomposing on the high-voltage cathode side.

[0005] Therefore, there is an urgent need to develop a high-performance, intrinsically safe gel polymer electrolyte combined with a solidified cathode to prepare a high-performance solid-state lithium battery that can meet the thermogravimetric standards of all-solid-state batteries. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a polyionic liquid gel electrolyte and its applications. Specifically, the present invention provides a solid-state lithium battery based on a polyionic liquid gel electrolyte and a solidified cathode that meets the thermogravimetric requirements of all-solid-state batteries, and a method for its preparation. The polyionic liquid gel electrolyte is composed of a novel N-type electrolyte with fluorinated branches. + The solidified porous cathode, composed of a cation-centered polyionic liquid monomer, an ionic liquid plasticizer, a lithium salt, and an initiator, and coated with an organic-inorganic composite solid electrolyte, constructs a continuous and stable ion transport channel from the inside of the electrode to the electrolyte bulk phase. This is expected to effectively improve the electrochemical performance and energy density of solid-state lithium batteries while ensuring intrinsic high safety and thermal stability.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polyionic liquid gel electrolyte, wherein the precursor solution of the polyionic liquid gel electrolyte comprises, by weight percentage, the following components: N + Cationic center polyionic liquid monomer 30%~90%; Ionic liquid plasticizer 10%~70%; Lithium salt A: 10%~80%.

[0008] The polyionic liquid gel electrolyte provided by this invention introduces N + The combination of cationic-centered polyionic liquid monomers and ionic liquid plasticizers results in excellent thermal stability and electrochemical performance, effectively improving the safety and cycle stability of solid-state lithium batteries.

[0009] The N provided by this invention +The cationic center polyionic liquid monomer is an N-type monomer containing fluorinated branches. + Cationic-centered polyionic liquid monomer.

[0010] In this invention, the precursor solution of the polyionic liquid gel electrolyte, by weight percentage, contains N + The amount of cationic center polyionic liquid monomer can be 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, etc.

[0011] In this invention, the amount of ionic liquid plasticizer in the precursor solution of the polyionic liquid gel electrolyte can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, 70%, etc., by weight percentage.

[0012] In this invention, the amount of lithium salt A in the precursor solution of the polyionic liquid gel electrolyte can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 80%, etc., by weight percentage.

[0013] Preferably, the N + The cationic-centered polyionic liquid monomer was prepared by the following method: (A1) A nucleophilic substitution reaction is carried out between a secondary amine raw material and an olefinic halide to obtain an N-olefinic amine salt; (A2) The N-olefinic amine salt obtained in step (A1) is nucleophilically substituted with a halofluorinated alkane to undergo a quaternization reaction, resulting in a polyionic liquid monomer with a halo anion. (A3) The polyionic liquid monomer containing halide anions obtained in step (A2) is subjected to an anion exchange reaction with lithium salt B to obtain the N+ Cationic-centered polyionic liquid monomer.

[0014] Preferably, the secondary amine raw material in step (A1) has the structure shown in Formula I: Formula I; Among them, R 1 R 2 Each is independently selected from C1-C10 straight-chain or branched alkyl groups, or any one of pyrrolidinyl, morpholinyl, or piperidinyl groups having a carbon-branched structure; the dashed line indicates R. 1 R 2 They are either not connected, or connected in a loop.

[0015] Preferably, R 1 R 2 Each is independently selected from C1-C10 straight-chain or branched alkyl groups, and R 1 R 2 They are either not connected, or connected in a loop.

[0016] Preferably, the secondary amine raw material in step (A1) includes tetrahydropyrrole ( ) and / or dimethylamine ( ).

[0017] Preferably, the olefinic halide of step (A1) has the structure shown in Formula II: Formula II; Wherein, X is selected from halogens, such as F, Cl, Br, I, etc.; m is an integer from 0 to 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, or 9).

[0018] Preferably, the olefinic halide in step (A1) includes allyl bromide ( ) and / or 4-chloro-1-butene ( ).

[0019] Preferably, the halofluorinated alkane described in step (A2) has the structure shown in Formula III: Formula III; Among them, R f It is one of the following: an F atom, an alkyl chain containing at least one F atom, and an alkyl chain containing at least one C atom; Y is selected from halogens, such as F, Cl, Br, I, etc.; n is an integer from 0 to 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, or 9).

[0020] Preferably, the halofluorinated alkane in step (A2) includes 1-bromo-4,4,4-trifluorobutane ( ) and / or 1-chloro-4-fluorobutane ( ).

[0021] Preferably, the lithium salt B in step (A3) includes any one or a combination of at least two of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or lithium perchlorate (LiClO4).

[0022] Preferably, the molar ratio of the secondary amine raw material and the olefinic halide in step (A1) is 1:(1.1~1.5), for example, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45 or 1:1.5, etc.

[0023] Preferably, the temperature of the nucleophilic substitution reaction in step (A1) is 0~50℃, for example 0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, and more preferably 0~25℃.

[0024] Preferably, the nucleophilic substitution reaction in step (A1) takes 1 to 72 hours, for example, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 70 hours, or 72 hours, and is more preferably 10 to 20 hours.

[0025] Preferably, the molar ratio of the N-olefinic amine salt and the fluorinated haloalkane in step (A2) is 1:(1.1~1.5), for example, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45 or 1:1.5, etc.

[0026] Preferably, the temperature of the quaternization reaction in step (A2) is 50~100℃, such as 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, and more preferably 75~95℃.

[0027] Preferably, the quaternization reaction time in step (A2) is 1 to 72 h, for example, 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 50 h, 55 h, 60 h, 70 h or 72 h, and more preferably 20 to 30 h.

[0028] Preferably, the molar ratio of the polyionic liquid monomer with halide anions and lithium salt B in step (A3) is 1:(0.5~3), such as 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc.

[0029] Preferably, the temperature of the anion exchange reaction in step (A3) is 20~45℃, such as 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃ or 45℃, and more preferably 25~30℃.

[0030] Preferably, the anion exchange reaction time in step (A3) is 1 to 48 h, such as 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h or 48 h, and more preferably 6 to 24 h.

[0031] For example, when the lithium salt B in step (A3) is lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and R in formula III f When N is -CF3, + The synthesis reaction formula for the cationic-centered polyionic liquid monomer is shown below: Preferably, the ionic liquid plasticizer comprises any one or a combination of at least two of the following: N,N-dimethylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-ethyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-methyl-N-isobutylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-ethyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt, and N-butyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt.

[0032] Preferably, the lithium salt A comprises any one or a combination of at least two of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), or lithium tetrafluoroborate (LiBF4).

[0033] Secondly, the present invention provides a solidified positive electrode, wherein the raw materials for preparing the solidified positive electrode include a porous positive electrode, oxide solid electrolyte particles, a precursor solution of the polyionic liquid gel electrolyte described in the first aspect, and a photoinitiator.

[0034] Preferably, the porous cathode is made of any one of lithium-rich manganese-based, nickel-cobalt-manganese lithium, lithium iron phosphate, and lithium cobalt oxide.

[0035] Preferably, the oxide solid electrolyte particles include any one or a combination of at least two of LATP, LAGP, LLZO, and LLZTO.

[0036] Preferably, the particle size of the oxide solid electrolyte particles is 0.1~1μm, such as 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, etc., and more preferably 0.2~0.5μm.

[0037] Preferably, the photoinitiator comprises any one or a combination of at least two of 1-hydroxycyclohexylphenyl ketone (HCPK), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), or 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP).

[0038] Preferably, based on 100% by weight of the precursor solution of the polyionic liquid gel electrolyte, the amount of the oxide solid electrolyte particles is 5% to 50%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, and preferably 10% to 30%.

[0039] Preferably, based on 100% by weight of the precursor solution of the polyionic liquid gel electrolyte, the amount of the photoinitiator is 0.01% to 5%, for example, 0.01%, 0.03%, 0.05%, 0.08%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0040] Preferably, the solidified positive electrode is prepared by the following method: The amount of N in the formula + A precursor solution is obtained by mixing a cationic center polyionic liquid monomer, an ionic liquid plasticizer, and lithium salt A. Then, oxide solid electrolyte particles and a photoinitiator are added and mixed to obtain a mixture. The mixture is then placed on the surface of a porous cathode (e.g., by scraping, casting, or dripping) and then subjected to in-situ free radical polymerization to obtain the solidified cathode.

[0041] Preferably, the in-situ free radical polymerization is carried out under UV light irradiation for a duration of 2 to 10 minutes, such as 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0042] Thirdly, the present invention provides a solid-state lithium battery, the solid-state lithium battery comprising a solidified positive electrode, a separator, a negative electrode, and an electrolyte; The solidified cathode is as described in the second aspect; The raw materials for preparing the electrolyte include the precursor solution of the polyionic liquid gel electrolyte as described in the first aspect.

[0043] Preferably, the diaphragm comprises a GF / A diaphragm.

[0044] Preferably, the negative electrode comprises any one of silicon-carbon, lithium metal, or graphite.

[0045] Fourthly, the present invention provides a method for preparing a solid-state lithium battery as described in the third aspect, the method comprising the following steps: (1) Solidified positive electrode, separator and negative electrode are combined by stacking and packaged with aluminum-plastic film to obtain battery cell; (2) Add the amount of N in the formula + A precursor solution is obtained by mixing a cationic center polyionic liquid monomer, an ionic liquid plasticizer, and lithium salt A. Then, a thermal initiator is added to obtain a mixed solution. The mixed solution is then injected into the cell. After sufficient impregnation, in-situ free radical polymerization is carried out to obtain the solid-state lithium battery.

[0046] Preferably, the thermal initiator in step (2) includes any one or a combination of at least two of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), or potassium persulfate (KPS).

[0047] Preferably, in step (2), the amount of thermal initiator is 0.01% to 5%, based on the weight of the precursor solution as 100%, for example, 0.01%, 0.03%, 0.05%, 0.08%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0048] Preferably, the in-situ free radical polymerization in step (2) is carried out under heating conditions, the heating temperature is 60~80℃, for example 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃ or 80℃, etc., and the heating time is 4~15 h, for example 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc.

[0049] Compared with the prior art, the present invention has the following beneficial effects: The solid-state lithium battery based on polyionic liquid gel electrolyte provided by this invention abandons the traditional technical route that relies on low-flash-point organic solvents as plasticizers, and instead uses non-volatile, non-flammable, and thermally stable N-type electrolytes. + The cationic-centered polyionic liquid monomer is used as an ion transport additive. This design not only lowers the polymer's glass transition temperature and enhances chain segment mobility, but also optimizes ion migration kinetics.

[0050] On the positive electrode side, this invention employs a solidification strategy involving organic-inorganic composite electrolyte coating, effectively constructing ion transport channels within the porous electrode sheet while simultaneously improving the continuity of the electrode / electrolyte interface contact, thereby achieving long-cycle stability of the battery. Furthermore, the doping of oxide solid electrolyte particles further enhances the mechanical properties of the solidified interface layer, provides rapid ion transport channels, and effectively broadens the oxidation potential to improve compatibility with high-voltage positive electrodes.

[0051] The resulting solid-state lithium battery, which meets the thermal weight loss standard for all-solid-state batteries, is expected to significantly improve the electrochemical performance and energy density of solid-state batteries while ensuring intrinsic safety and effectively preventing thermal runaway. Detailed Implementation

[0052] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0053] Unless otherwise specified, the raw materials involved in the specific embodiments of this invention are all conventional materials in the field and can be obtained by purchasing commercially available products.

[0054] It should be noted that all the following operations are performed in a light-off glove box filled with argon gas, where the water and oxygen content are both below 0.01 ppm.

[0055] Preparation Example 1 This preparation example provides an N containing fluorinated branches. + The structural formula of the cationic-centered polyionic liquid monomer P1 is shown below: .

[0056] The preparation method includes the following steps: (1) Tetrahydropyrrole A1 and allyl bromide in a molar ratio of 1:1.5 were dissolved in diethyl ether and nucleophilic substitution reaction was carried out at 0°C for 12 hours to obtain N-allylpyrrole B1. (2) The N-allylpyrrolidine B1 and 1-bromo-4,4,4-trifluorobutane obtained in step (1) with a molar ratio of 1:1.3 were dissolved in ethyl acetate and subjected to a quaternization reaction at 85°C for 24 hours with stirring to obtain a product containing Br. - N of anions + Cationic-centered polyionic liquid monomer C1; (3) The N obtained in step (2) with a molar ratio of 1:3 + The cationic-centered polyionic liquid monomer C1 and LiTFSI were subjected to anion exchange reaction at 30°C for 20 hours under stirring to obtain the N containing fluorinated branches. + Cationic-centered polyionic liquid monomer P1.

[0057] The specific reaction formulas for steps (1) to (3) above are shown below: .

[0058] Preparation Example 2 This preparation example provides an N containing fluorinated branches. + The structural formula of the cationic-centered polyionic liquid P2 is shown below: .

[0059] The preparation method includes the following steps: (1) Dimethylamine A2 and 4-chloro-1-butene in a molar ratio of 1:1.3 were subjected to a nucleophilic substitution reaction at 5°C for 20 hours to obtain N,N-dimethyl-3-buten-1-amine B2. (2) The N,N-dimethyl-3-buten-1-amine B2 obtained in step (1) with a molar ratio of 1:1.5 and 1-chloro-4-fluorobutane were subjected to a quaternization reaction at 80°C for 28 hours to obtain a product containing Cl. - N of anions + Cationic-centered polyionic liquid monomer C2; (3) The N obtained in step (2) with a molar ratio of 1:3 + The cationic-centered polyionic liquid monomer C2 and LiTFSI were subjected to anion exchange reaction at 26°C for 12 hours under stirring to obtain the N containing fluorinated branches. + P2 is a cationic polyionic liquid with a cationic center.

[0060] The specific reaction formulas for steps (1) to (3) above are shown below: .

[0061] Example 1 A polyionic liquid gel electrolyte, wherein the precursor solution of the polyionic liquid gel electrolyte comprises, by weight percentage, the following components: N + 30% cationic-centered polyionic liquid monomer; 50% ionic liquid plasticizer; Lithium salt A 20%; Where, N + The cationic-centered polyionic liquid monomer is the N-containing fluorinated branched monomer provided in Preparation Example 1. + The cationic center polyionic liquid monomer P1, the ionic liquid plasticizer is N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, and the lithium salt A is LiTFSI.

[0062] The precursor solution of the polyionic liquid gel electrolyte was prepared by the following method: According to the above formula, add N to the reaction vessel. + The cationic center polyionic liquid monomer was mixed with ionic liquid plasticizer and lithium salt A, and stirred continuously for 50 min under completely dark conditions to obtain a clear and transparent precursor solution.

[0063] A solid-state positive electrode, said solid-state positive electrode being prepared by the following method: Take a portion of the precursor solution prepared above, then add oxide solid electrolyte particles and photoinitiator, and sonicate and stir thoroughly to obtain a mixture. Then drop the mixture onto the surface of the porous lithium cobalt oxide cathode. After it is completely wetted, place it in a small transition chamber under negative pressure for 10 minutes. Then irradiate it with a UV lamp with a wavelength of 365 nm for 5 minutes to fully polymerize and solidify it to obtain the solidified cathode. The oxide solid electrolyte particles are LLZTO nanoparticles (0.3 μm in diameter), and their amount is 10% of the weight of the precursor solution in this step; the photoinitiator is TPO, and its amount is 0.05% of the weight of the precursor solution in this step.

[0064] A solid-state lithium battery, the preparation method of which includes the following steps: (1) The solidified positive electrode, GF / A separator and negative electrode (lithium metal foil, 120μm) prepared above are stacked and assembled, and then sealed on three sides with aluminum-plastic film to obtain a battery cell; (2) Take the remaining precursor solution prepared above, add thermal initiator and stir evenly to obtain a mixed solution. Then inject the mixed solution into the cell, fully wet it and vacuum seal it. Then let it stand at room temperature for 12 h and then transfer it to a 65℃ forced-air oven for 15 h. After cooling to room temperature, a solid lithium battery based on polyionic liquid gel electrolyte and solidified positive electrode is obtained. In step (2), the thermal initiator is AIBN, and its amount is 0.1% of the weight of the precursor solution in this step.

[0065] Example 2 The only difference between this embodiment and Embodiment 1 is that N is... + The cationic-centered polyionic liquid monomer was replaced with an equal weight of the fluorinated branched N provided in Preparation Example 2. + The cationic-centered polyionic liquid P2, along with other substances, amounts, and preparation methods, is the same as in Example 1.

[0066] Example 3 The only difference between this embodiment and Example 1 is that, in the preparation of solid-state lithium batteries, the thermal initiator (AIBN) is replaced with an equal weight of BPO in step (2), and the polymerization method in this step is replaced with placing it in a high-temperature oven at 80°C for 8 hours. Other substances, amounts and steps are the same as in Example 1.

[0067] Example 4 The only difference between this embodiment and Example 1 is that, when preparing the solidified cathode, the oxide solid electrolyte particles (LLZTO nanoparticles with a particle size of 0.3 μm) are replaced with an equal weight of LATP nanoparticles with a particle size of 0.15 μm. In addition, when preparing the solid-state lithium battery, the polymerization initiation method in step (2) is replaced by transferring to a high-temperature oven at 60°C for 12 h. All other substances, amounts and steps are the same as in Example 1.

[0068] Example 5 The only difference between this embodiment and Example 1 is that, when preparing the solidified cathode, the amount of oxide solid electrolyte particles (LLZTO nanoparticles with a particle size of 0.3 μm) is increased to 30% of the weight of the precursor solution used in this step. All other substances, amounts, and preparation methods are the same as in Example 1.

[0069] Example 6 The only difference between this embodiment and Example 1 is the amount of each component in the precursor solution, as detailed below: N + 60% cationic-centered polyionic liquid monomer; 10% ionic liquid plasticizer; Lithium salt A 30%.

[0070] Example 7 The only difference between this embodiment and Example 1 is the amount of each component in the precursor solution, as detailed below: N + Cationic-centered polyionic liquid monomers account for 80%; 10% ionic liquid plasticizer; Lithium salt A 10%.

[0071] Comparative Example 1 The only difference between this comparative example and Example 1 is that the ionic liquid plasticizer N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt was not added to the precursor solution, and N... + The weight percentage of the cationic-centered polyionic liquid monomer P1 was increased to 60%, and the weight percentage of LiTFSI was increased to 40%. Other substances, amounts, and preparation methods were the same as in Example 1.

[0072] Comparative Example 2 The only difference between this comparative example and Example 1 is that the ionic liquid plasticizer N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt in the precursor solution is replaced with an equal weight of the organic solvent ethylene glycol dimethyl ether (DME). All other substances, amounts, and preparation methods are the same as in Example 1.

[0073] Comparative Example 3 The only difference between this comparative example and Example 1 is that the solidified cathode preparation step is not included, and when preparing the solidified lithium battery, the solidified cathode in step (1) is replaced with a porous lithium cobalt oxide cathode (i.e., the cathode sheet is not subjected to solidification treatment of organic-inorganic composite electrolyte).

[0074] Comparative Example 4 The only difference between this comparative example and Example 1 is that N was not added to the precursor solution. + The cation-centered polyionic liquid monomer was used, with the weight percentage of ionic liquid plasticizer increased to 71.4% and the weight percentage of LiTFSI increased to 28.6%. Other substances, dosages, and preparation methods were the same as in Example 1.

[0075] Comparative Example 5 The only difference between this comparative example and Example 1 is that the N in the precursor solution is... + The cationic center polyionic liquid monomer is replaced with an equal weight of vinylene carbonate (VC) monomer.

[0076] The thermal weight loss rate of the solid-state lithium batteries provided in the embodiments and comparative examples of the present invention was tested using the following methods: (1) Pretreatment: Before the formal test begins, the individual battery cells need to undergo a pretreatment cycle to ensure that the experimental subject is in an activated and stable state, and the experimental subject is fully discharged. Refer to the "All-Solid-State Battery Judgment Method" (T / CSAE 434-2025) for the following steps: A) Charge the battery cell at a constant current of not less than I3 as specified by the manufacturer until the cell reaches the charging termination voltage specified in the manufacturer's technical conditions, then switch to constant voltage charging. Stop charging when the charging current drops to 0.05I1, and let it rest for 1 hour after charging. Wherein, I3 and I1 refer to the current corresponding to 1 / 3C and 1C multipliers, respectively.

[0077] B) Discharge to the manufacturer's specified discharge cutoff condition using a current of not less than I3, and measure the discharge capacity (in Ah).

[0078] C) Let it sit for 30 minutes.

[0079] D) Repeat the above steps 3 times. The discharge capacity of each of the 3 discharges should not be less than the rated capacity and should not exceed 10% of the rated capacity.

[0080] (2) Drying test: A) Make a hole in the experimental subject (i.e., the solid-state lithium battery), and break the soft pack at the side seal (the break length should be no less than 2 cm ± 0.5 cm). The exposure time after breaking should not exceed 5 min.

[0081] B) Record the mass of the experimental subject, denoted as M0.

[0082] C) Place the experimental object in a vacuum drying oven at 120℃ for 6 hours. Vacuum treatment is performed every half hour during the test, and the vacuum is maintained for no less than 10 minutes. The vacuum degree is between -0.095 and -0.1 MPa.

[0083] After the test is completed, the vacuum drying oven is cooled to below 50°C, and the test subject is removed.

[0084] D) Record the mass of the experimental subject, denoted as M1.

[0085] (3) Data processing: The formula for calculating the battery weight loss rate η is as follows: η=(M0-M1) / M0×100% Where M0 is the initial mass of the experimental object and M1 is the final mass of the experimental object.

[0086] The performance test results are shown in Table 1.

[0087] Table 1 As can be seen from Table 1, the solid-state lithium batteries prepared in Examples 1-7, Comparative Examples 1, 3 and 4 of the present invention can all meet the standard of less than 1% thermal weight loss of all-solid-state batteries.

[0088] Comparative Example 2, due to the use of ethylene glycol dimethyl ether (DME) with a lower boiling point instead of the ionic liquid plasticizer N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, achieved a thermal weight loss rate of 46.13% after being placed under negative pressure at 120°C for 6 hours, which does not meet the standard of less than 1% thermal weight loss for all-solid-state batteries.

[0089] Comparative Example 5 used vinylene carbonate, which has poor thermal stability, instead of N. + The cationic-centered polyionic liquid monomer exhibited a thermal weight loss of 29.36% after being placed under negative pressure at 120°C for 6 hours, which does not meet the standard of less than 1% thermal weight loss for all-solid-state batteries. Cycle stability tests were conducted on the solid-state lithium batteries provided in the embodiments and comparative examples of this invention. The test methods are as follows: A stacking pressure of 5 MPa is applied to the solid-state lithium battery using a fixture, and then it is transferred to Neware's constant temperature (30°C) battery test cabinet. After being left for 6 hours, the discharge specific capacity of the battery at 0.1C is tested using a constant current charge-discharge test method. After 200 cycles, the total capacity retention rate can be calculated, thus reflecting its cycle stability.

[0090] The performance test results are shown in Table 2.

[0091] Table 2 As can be seen from Table 2, the solid-state lithium batteries provided in the embodiments of the present invention all have good cycle stability.

[0092] Compared with Example 1, the cycle stability of the solid-state lithium batteries provided by Comparative Example 1 and Comparative Example 3 was significantly reduced.

[0093] Compared with Example 1, although the thermal weight loss rate of Comparative Example 4 meets the requirements and the capacity retention rate only decreases slightly, it does not contain a polyionic liquid matrix and is a liquid electrolyte, which does not meet the requirement of "the tested sample must pass the visual inspection of the broken opening and show no liquid leakage" in the "All-Solid-State Battery Judgment Method" (T / CSAE 434-2025). Therefore, it cannot be judged as a solid-state lithium battery.

[0094] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate the polyionic liquid gel electrolyte and its application, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyionic liquid gel electrolyte, characterized in that, The precursor solution of the polyionic liquid gel electrolyte comprises the following components by weight percentage: N + Cationic center polyionic liquid monomer 30%~90%; Ionic liquid plasticizer 10%~70%; Lithium salt A: 10%~80%.

2. The polyionic liquid gel electrolyte according to claim 1, characterized in that, The N + The cationic-centered polyionic liquid monomer was prepared by the following method: (A1) A nucleophilic substitution reaction is carried out between a secondary amine raw material and an olefinic halide to obtain an N-olefinic amine salt; (A2) The N-olefinic amine salt obtained in step (A1) is nucleophilically substituted with a halofluorinated alkane to undergo a quaternization reaction, resulting in a polyionic liquid monomer with a halo anion. (A3) The polyionic liquid monomer containing halide anions obtained in step (A2) is subjected to an anion exchange reaction with lithium salt B to obtain the N + Cationic-centered polyionic liquid monomer.

3. The polyionic liquid gel electrolyte according to claim 2, characterized in that, The secondary amine raw material in step (A1) has the structure shown in Formula I: Formula I; Among them, R 1 R 2 Each is independently selected from C1-C10 straight-chain or branched alkyl groups, or any one of pyrrolidinyl, morpholinyl, or piperidinyl groups having a carbon-branched structure; the dashed line indicates R. 1 R 2 Not connected, or connected in a loop; Preferably, R 1 R 2 Each is independently selected from C1-C10 straight-chain or branched alkyl groups, and R 1 R 2 Not connected, or connected in a loop; Preferably, the secondary amine raw material in step (A1) includes tetrahydropyrrole and / or dimethylamine; Preferably, the olefinic halide of step (A1) has the structure shown in Formula II: Formula II; Wherein, X is selected from halogens; m is an integer between 0 and 10; Preferably, the olefinic halide in step (A1) comprises allyl bromide and / or 4-chloro-1-butene; Preferably, the halofluorinated alkane described in step (A2) has the structure shown in Formula III: Formula III; Among them, R f It is one of the following: an F atom, an alkyl chain containing at least one F atom, and an alkyl chain containing at least one C atom; Y is selected from halogens; n is an integer between 0 and 10; Preferably, the halofluorinated alkane in step (A2) includes 1-bromo-4,4,4-trifluorobutane and / or 1-chloro-4-fluorobutane; Preferably, the lithium salt B in step (A3) includes any one or a combination of at least two of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, or lithium perchlorate.

4. The polyionic liquid gel electrolyte according to claim 2 or 3, characterized in that, The molar ratio of the secondary amine raw material and the olefinic halide in step (A1) is 1:(1.1~1.5); Preferably, the temperature of the nucleophilic substitution reaction in step (A1) is 0~50℃, more preferably 0~25℃; Preferably, the nucleophilic substitution reaction in step (A1) takes 1 to 72 hours, more preferably 10 to 20 hours; Preferably, the molar ratio of the N-olefinic amine salt and the fluorinated haloalkane in step (A2) is 1:(1.1~1.5); Preferably, the temperature of the quaternization reaction in step (A2) is 50~100℃, more preferably 75~95℃; Preferably, the quaternization reaction in step (A2) takes 1 to 72 hours, more preferably 20 to 30 hours.

5. The polyionic liquid gel electrolyte according to any one of claims 2-4, characterized in that, In step (A3), the molar ratio of the polyionic liquid monomer with halide anions to lithium salt B is 1:(0.5~3). Preferably, the temperature of the anion exchange reaction in step (A3) is 20~45℃, more preferably 25~30℃; Preferably, the anion exchange reaction in step (A3) takes 1 to 48 hours, more preferably 6 to 24 hours.

6. The polyionic liquid gel electrolyte according to any one of claims 1-5, characterized in that, The ionic liquid plasticizer includes any one or a combination of at least two of the following: N,N-dimethylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-ethyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-methyl-N-isobutylpyrrolidine bis(trifluoromethanesulfonyl)imide salt, N-ethyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt, N-propyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt, and N-butyl-N-methylpiperidine bis(trifluoromethanesulfonyl)imide salt. Preferably, the lithium salt A comprises any one or a combination of at least two of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium difluorooxalate borate, lithium di(oxalate borate), or lithium tetrafluoroborate.

7. A solid-state positive electrode, characterized in that, The raw materials for preparing the solidified positive electrode include porous positive electrode, oxide solid electrolyte particles, precursor solution of polyionic liquid gel electrolyte according to any one of claims 1-6, and photoinitiator; Preferably, the porous cathode material includes any one of lithium-rich manganese-based, nickel-cobalt-manganese lithium, lithium iron phosphate, and lithium cobalt oxide; Preferably, the oxide solid electrolyte particles include any one or a combination of at least two of LATP, LAGP, LLZO, and LLZTO; Preferably, the particle size of the oxide solid electrolyte particles is 0.1~1μm, more preferably 0.2~0.5μm; Preferably, the photoinitiator comprises any one or a combination of at least two of 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, or 2-hydroxy-2-methyl-1-phenyl-1-propanone; Preferably, based on 100% by weight of the precursor solution of the polyionic liquid gel electrolyte, the amount of the oxide solid electrolyte particles is 5% to 50%, more preferably 10% to 30%; Preferably, based on 100% by weight of the precursor solution of the polyionic liquid gel electrolyte, the amount of the photoinitiator is 0.01% to 5%; Preferably, the solidified positive electrode is prepared by the following method: The amount of N in the formula + A precursor solution is obtained by mixing a cationic center polyionic liquid monomer, an ionic liquid plasticizer, and lithium salt A. Then, oxide solid electrolyte particles and a photoinitiator are added and mixed to obtain a mixture. The mixture is then placed on the surface of a porous cathode and then subjected to in-situ free radical polymerization to obtain the solidified cathode. Preferably, the in-situ free radical polymerization is carried out under UV light irradiation for 2 to 10 minutes.

8. A solid-state lithium battery, characterized in that, The solid-state lithium battery includes a solidified positive electrode, a separator, a negative electrode, and an electrolyte; The solidified positive electrode is the solidified positive electrode as described in claim 7; The raw materials for preparing the electrolyte include the precursor solution of the polyionic liquid gel electrolyte as described in any one of claims 1-6; Preferably, the diaphragm comprises a GF / A diaphragm; Preferably, the negative electrode comprises any one of silicon-carbon, lithium metal, or graphite.

9. A method for preparing a solid-state lithium battery as described in claim 8, characterized in that, The preparation method includes the following steps: (1) Solidified positive electrode, separator and negative electrode are combined by stacking and packaged with aluminum-plastic film to obtain battery cell; (2) Add the amount of N in the formula + A precursor solution is obtained by mixing a cationic center polyionic liquid monomer, an ionic liquid plasticizer, and lithium salt A. A thermal initiator is then added to obtain a mixed solution. The mixed solution is then injected into the cell and in-situ free radical polymerization is carried out to obtain the solid-state lithium battery.

10. The preparation method according to claim 9, characterized in that, The thermal initiator in step (2) includes any one or a combination of at least two of azobisisobutyronitrile, benzoyl peroxide, or potassium persulfate; Preferably, in step (2), the amount of thermal initiator is 0.01% to 5% based on 100% by weight of the precursor solution; Preferably, the in-situ free radical polymerization in step (2) is carried out under heating conditions, wherein the heating temperature is 60~80℃ and the heating time is 4~15 h.

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