Gel type lithium ion battery

Abstract

The invention discloses a gel type lithium ion battery, which comprises a positive plate, a negative plate and a gel electrolyte, in the gel type lithium ion battery, the liquid injection amount of a precursor electrolyte per Ah is recorded as a, the distance of the edge of at least one side edge of a negative electrode active material layer exceeding the edge of a positive electrode active material layer is recorded as b, and a and b satisfy 0.3 < = a * b < = 15. According to the present invention, the overhang area interface characteristic is improved by regulating and controlling the distance of the negative plate exceeding the edge of the positive plate and the injection amount of the gel electrolyte precursor electrolyte, the lithium precipitation or swelling risk of the overhang area is reduced, the safety of the battery is improved, and the gel type lithium ion battery has high energy density.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium secondary batteries, and in particular relates to a gel-type lithium ion battery. Background Art

[0002] Lithium secondary batteries, also known as lithium-ion batteries or LIBs, are rechargeable batteries that rely primarily on the movement of lithium ions between the positive and negative electrodes of the battery to store and release energy. They are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, long cycle life, and low self-discharge rate. Gel-type lithium-ion batteries are lithium-ion batteries that use gel electrolytes, which have some unique advantages and disadvantages. Gel electrolytes are usually gel-type systems composed of a polymer matrix, lithium salts, and organic solvents (plasticizers). This electrolyte combines the high ionic conductivity of liquid electrolytes with the good mechanical properties and thermal stability of solid electrolytes. Therefore, research on gel-type lithium-ion batteries has gradually increased.

[0003] In the current design of battery cells, if the negative electrode plate does not have a position to accept lithium ions, lithium ions will precipitate on the surface of the negative electrode plate to form lithium dendrites. These lithium dendrites may pierce the diaphragm, thereby causing an internal short circuit and thermal runaway. For safety reasons, the negative electrode is generally designed to be excessive in the positive electrode, usually by extending the length and / or width direction of the negative electrode active material layer beyond the edge of the positive electrode active material layer, that is, the negative electrode plate includes an overhang area (i.e., the area where the negative electrode plate and the positive electrode plate do not overlap) and a non-overhang area (i.e., the area where the negative electrode plate and the positive electrode plate overlap). However, after multiple fast charging cycles, lithium precipitation will also occur in the overhang area, and the continuous accumulation of precipitated lithium will also cause the diaphragm to be pierced, bringing serious safety hazards to lithium secondary batteries. By designing the overhang area, on the one hand, more lithium embedding sites can be provided to reduce the safety risks caused by lithium precipitation piercing the isolation membrane, and on the other hand, the safety risks caused by the misalignment of the pole pieces in the battery process can be reduced. However, too large an overhang will reduce the energy density, and too small an overhang will make it difficult to achieve the desired effect of improving safety performance. At the same time, during the long cycle of the battery, the electrolyte will settle, that is, the electrolyte will decrease or disappear in the overhang area, which will increase the problem of lithium plating in the overhang area.

[0004] Therefore, studying how to slow down the problem of lithium deposition in the overhang area of ​​the negative electrode sheet has become a hot topic. For example, in the prior art, the problem of lithium deposition in the overhang area is alleviated by increasing the surface density of the active layer in the overhang area, thereby extending the number of cycles and the service life of the lithium-ion battery. However, this method will bring the risk of edge bulging in the overhang area, and increasing the surface density of the active layer in the overhang area will also lead to a reduction in the energy density of the battery. For example, in the prior art, the amount of specific solvents used in the electrolyte is adjusted in combination with other parameters to reduce lithium deposition in the overhang area. However, these solvents are easily decomposed and gasified at high temperatures, thereby degrading the electrode interface and sacrificing the high temperature performance of the battery. Summary of the invention

[0005] In view of this, the primary purpose of the present invention is to provide a gel-type lithium-ion battery, which improves the interface characteristics of the overhang area by regulating the distance that the negative electrode sheet exceeds the edge of the positive electrode sheet and the injection amount of the gel electrolyte precursor electrolyte, reduces the risk of lithium plating in the overhang area, and improves the safety of the battery.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a gel-type lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet and a gel electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector, the gel electrolyte is formed by an in-situ cross-linking polymerization reaction of a precursor electrolyte, and in the gel-type lithium-ion battery, the injection amount of the precursor electrolyte per Ah is recorded as a, and the distance that the edge of at least one side of the negative electrode active material layer exceeds the edge of the positive electrode active material layer is recorded as b, and a and b satisfy 0.3≤a×b≤15.

[0008] In a further solution, a and b satisfy 1.0≤a×b≤8.

[0009] In a further embodiment, a distance b by which an edge of at least one side of the negative electrode active material layer exceeds an edge of the positive electrode active material layer satisfies 0.1 mm≤b≤5 mm.

[0010] In a further embodiment, the precursor electrolyte comprises a basic electrolyte, a polymerizable monomer and an initiator, wherein the basic electrolyte contains an electrolyte lithium salt, an organic solvent and an additive.

[0011] In a further embodiment, the electrolyte lithium salt is at least one of LiClO4, LiPF6, LiBF4, LiODFB, LiFSI, LiTFSi, LiCF3SO3, LiN(CF3SO2)2, and LiB(C2O4)2.

[0012] In a further embodiment, the organic solvent is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, 1,4-butyrolactone, dimethyltetrahydrofuran, 1,2-dimethoxyethane, methyl acetate, methyl propionate, ethyl propionate, methyl butyrate, trifluoromethylethylene carbonate, dimethyl sulfoxide, cyclopentane, 4-methyl-1,3-butyrolactone, propane sultone, ethylene sulfite, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.

[0013] In a further embodiment, the additive is at least one of VC, 1,3-PS, LiBOB, VEC, VES, ES, PES, MMDS, DTD, FEC, LiPO2F2, SN, AND, TMSB, TMSP, TMSPi, diphenyldifluorosilane, tris(2,2,2-trifluoroethyl)phosphite, 4-propylvinyl sulfate, tris(2,2,2-trifluoroethyl)phosphite, and diethyl cyanomethyl phosphate.

[0014] A further solution is characterized in that, in the precursor electrolyte, the mass percentage of the polymerizable monomer is 1% to 10%, the mass percentage of the initiator is 0.01% to 0.5%, and the remainder is the basic electrolyte.

[0015] In a further embodiment, in the basic electrolyte, the concentration of the electrolyte lithium salt is 0.7 mol / L to 1.6 mol / L.

[0016] In a further embodiment, in the basic electrolyte, the content of the additive is ≤10wt%.

[0017] In a further embodiment, the polymerizable monomer is at least one of polyethylene glycol diacrylate, tetraethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, and ethoxylated trimethylolpropane triacrylate.

[0018] In a further embodiment, the initiator is a thermal initiator or a photoinitiator.

[0019] In a further embodiment, the initiator is at least one of 2,2-azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, dodecyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, and 2-hydroxy-2-methyl-1-phenylacetone.

[0020] In a further embodiment, the gel-type lithium-ion battery is a laminated battery or a wound battery.

[0021] Beneficial effects of the present invention:

[0022] The present invention effectively improves the interface characteristics of the overhang area by adjusting the injection amount of the gel electrolyte precursor electrolyte, improves the dynamic performance of the overhang area, reduces the risks of lithium plating and bulging in the overhang area and the negative electrode sheet, expands the process boundary of the gel-type lithium-ion battery and improves the fault tolerance of the process, improves the safety performance of the gel-type lithium-ion battery, and simultaneously adopts a smaller overhang, so that the gel-type lithium-ion battery has a higher energy density. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0025] The present invention provides a gel-type lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet and a gel electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector, and the gel electrolyte is formed by an in-situ crosslinking polymerization reaction of a precursor electrolyte. In the present invention, by controlling the injection amount of the precursor electrolyte of the gel-type lithium-ion battery and the distance that the edge of at least one side of the negative electrode active material layer exceeds the edge of the positive electrode active material layer, the interface characteristics of the overhang area are optimized, and the dynamic performance of the overhang area is improved, thereby reducing the risk of lithium deposition in the overhang area and the negative electrode sheet, improving the energy density of the gel-type lithium-ion battery, and improving the safety performance of the gel-type lithium-ion battery. At the same time, in the present application, since the use of carboxylic acid ester organic solvents is avoided, the problem of easy decomposition and gas production at high temperature, thereby deteriorating the interface of the electrode sheet, is avoided. The present application optimizes the interface characteristics of the electrode sheet and well ensures the stability of the high temperature performance of the lithium-ion battery.

[0026] Specifically, in the gel-type lithium-ion battery, the injection amount of the precursor electrolyte per Ah is recorded as a, and the distance by which the edge of at least one side of the negative electrode active material layer exceeds the edge of the positive electrode active material layer is recorded as b, then a and b satisfy 0.3≤a×b≤15. Preferably, a and b satisfy 1.0≤a×b≤8.

[0027] In a further embodiment, the distance b of the edge of at least one side of the negative electrode active material layer beyond the edge of the positive electrode active material layer satisfies 0.1 mm ≤ b ≤ 5 mm, for example, it can be 0.1 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.6 mm, 2 mm, 3 mm, 4 mm or 5 mm, preferably, b satisfies 0.1 mm ≤ b ≤ 2 mm. By adopting a smaller overhang, the gel-type lithium-ion battery of the present invention has a higher energy density.

[0028] It is understandable that in the gel-type lithium-ion battery, the positive electrode sheet, the negative electrode sheet, etc. can all adopt conventional compositions in the art, which will not be elaborated in detail here.

[0029] In the present invention, the gel electrolyte is formed by an in-situ crosslinking polymerization reaction of a gel electrolyte precursor electrolyte, wherein the composition of the gel electrolyte precursor electrolyte includes a basic electrolyte, a polymerizable monomer and an initiator, wherein the basic electrolyte contains an electrolyte lithium salt, an organic solvent and an additive.

[0030] Among them, the electrolyte lithium salt, organic solvent and additives can all adopt conventional compositions in the field. For example, the electrolyte lithium salt can be at least one of LiClO4, LiPF6, LiBF4, LiODFB, LiFSI, LiTFSi, LiCF3SO3, LiN(CF3SO2)2, and LiB(C2O4)2, but is not limited thereto.

[0031] The organic solvent may be at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, 1,4-butyrolactone, dimethyltetrahydrofuran, 1,2-dimethoxyethane, methyl acetate, methyl propionate, ethyl propionate, methyl butyrate, trifluoromethylethylene carbonate, dimethyl sulfoxide, cyclopentane, 4-methyl-1,3-butyrolactone, propane sultone, ethylene sulfite, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether, but is not limited thereto.

[0032] The additive may be at least one of VC (vinyl carbonate), 1,3-PS, LiBOB, VEC, VES, ES, PES, MMDS, DTD, FEC, LiPO2F2, SN, AND, TMSB, TMSP, TMSPi, diphenyldifluorosilane, tris(2,2,2-trifluoroethyl)phosphite, 4-propyl vinyl sulfate, tris(2,2,2-trifluoroethyl)phosphite, and diethyl cyanomethyl phosphate; preferably, the additive is at least one of VC, 1,3-PS, DTD, FEC, LiPO2F2, TMSB, and diethyl cyanomethyl phosphate, but is not limited thereto.

[0033] In the present invention, the polymerizable monomer may be a compound conventionally used in the art for gel electrolytes that can be cross-linked and polymerized to form a high molecular polymer under certain conditions. Specific examples include at least one of polyethylene glycol diacrylate, tetraethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, and ethoxylated trimethylolpropane triacrylate, but are not limited thereto.

[0034] The initiator may be a thermal initiator (initiating cross-linking polymerization by heating) or a photoinitiator (initiating cross-linking polymerization by light irradiation) according to different polymerization conditions of the polymerizable monomers. For example, it may be at least one of 2,2-azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, dodecyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, and 2-hydroxy-2-methyl-1-phenylacetone, but is not limited thereto.

[0035] Further, it is understood that the content of each component in the precursor electrolyte can be adjusted or confirmed based on methods or means well known to those skilled in the art. In some specific embodiments of the present invention, in the precursor electrolyte, the mass percentage of the polymerizable monomer is 1% to 10%, preferably 2% to 8%; the mass percentage of the initiator is 0.01% to 0.5%, and the remainder is the basic electrolyte. In the basic electrolyte, the concentration of the electrolyte lithium salt is 0.7mol / L to 1.6mol / L. In the basic electrolyte, the content of the additive is 0 to 10%, preferably 1% to 5%.

[0036] In the present invention, each component in the precursor electrolyte exists independently of each other or in the form of a mixture, and has excellent fluidity, and is a liquid with good fluidity at -30°C to 30°C. By cross-linking and polymerizing the precursor electrolyte in the present invention, the obtained gel electrolyte can be endowed with excellent mechanical strength and lithium ion mobility, and its temperature stability, especially high temperature stability, can be improved. In addition, its oxygen resistance stability can also be improved.

[0037] Furthermore, the preparation of the gel-type lithium-ion battery in the present invention is not particularly limited. After the positive electrode sheet, the separator and the negative electrode sheet are assembled into a battery cell in a conventional manner in the art, a precursor electrolyte is injected into the battery cell, and then an in-situ cross-linking polymerization reaction is performed to obtain the battery.

[0038] In the present invention, the type of the gel-type lithium-ion battery is not particularly limited, and is preferably a laminated battery or a wound battery.

[0039] The present invention is described below by means of specific examples. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0040] Example 1

[0041] This embodiment provides a gel-type lithium-ion battery, and its preparation and assembly process is as follows:

[0042] 1. Preparation of positive electrode

[0043] The positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O2, conductive carbon black SP and binder PVDF are dispersed in NMP solvent in a mass ratio of 98:1:1 and mixed evenly to obtain positive electrode slurry; the positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained after drying, cold pressing and cutting, wherein the coating amount per unit area on both sides is 180g / m 2 .

[0044] 2. Preparation of negative electrode sheet

[0045] The negative electrode active material graphite, the thickener sodium carboxymethyl cellulose, the adhesive styrene butadiene rubber, and the conductive agent acetylene black are mixed in a mass ratio of 97:1:1:1, and deionized water is added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry is evenly coated on the surface of the negative electrode current collector copper foil; the negative electrode sheet is obtained by drying, cold pressing, and slitting, wherein the coating amount per unit area on both sides is 110g / m 2 .

[0046] 3. Diaphragm

[0047] A 14μm polypropylene diaphragm is used.

[0048] 4. Preparation of gel electrolyte precursor

[0049] First, prepare the basic electrolyte in a glove box: 1M LiPF6, 1wt% additive VC, organic solvent EC:EMC:DEC=1:1:1 (vol). Then, add monomer polyethylene glycol diacrylate (7wt%) and initiator 2,2-azobisisobutyronitrile (0.3wt%) to the basic electrolyte, mix well to obtain the precursor electrolyte.

[0050] 5. Assembly of laminated batteries

[0051] The positive electrode sheet, separator and negative electrode sheet are stacked in order, and the separator is placed between the positive and negative electrode sheets to play an isolating role. The negative electrode active material layer in the negative electrode sheet extends beyond the edge of the positive electrode active material layer in the positive electrode sheet in both width and length directions, and the overhang distance (overhang) is 2 mm. An aluminum-plastic film is put in, and then baked at 80°C to remove water, and 6g of the corresponding precursor electrolyte is injected. After sealing, the electrolyte is fully infiltrated into the internal electrode sheet and separator of the battery, and then the battery is placed in a 60°C oven for in-situ thermal polymerization for 24 hours. After hot and cold pressing, formation, clamping, capacity division and other processes, a finished laminated battery with a capacity of 2Ah is obtained.

[0052] Example 2

[0053] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the injection amount of the precursor electrolyte per Ah is 2.5 g.

[0054] Example 3

[0055] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the injection amount of the precursor electrolyte per Ah is 4 g.

[0056] Example 4

[0057] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the injection amount of the precursor electrolyte per Ah is 5 g.

[0058] Example 5

[0059] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 0.1 mm.

[0060] Example 6

[0061] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 0.5 mm.

[0062] Example 7

[0063] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 5 mm.

[0064] Example 8

[0065] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 0.5 mm and the injection amount of the precursor electrolyte per Ah is 2 g.

[0066] Example 9

[0067] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 2 mm and the polymerizable monomer in the precursor electrolyte is tetraethylene glycol diacrylate.

[0068] Example 10

[0069] This embodiment provides a gel-type lithium-ion battery, which adopts the same implementation as that of Embodiment 1, except that the overhang area is 2 mm and the polymerizable monomer in the precursor electrolyte is pentaerythritol triacrylate.

[0070] Comparative Example 1

[0071] This comparative example provides a gel-type lithium-ion battery, which adopts the same implementation as that of Example 5, except that the precursor electrolyte is the base electrolyte.

[0072] Comparative Example 2

[0073] This comparative example provides a gel-type lithium-ion battery, which adopts the same implementation as that of Example 1, except that the precursor electrolyte is the base electrolyte.

[0074] Comparative Example 3

[0075] This comparative example provides a gel-type lithium-ion battery, which adopts the same implementation as Example 1, except that the overhang area is 5 mm and the injection amount of the precursor electrolyte per Ah is 4 g.

[0076] Comparative Example 4

[0077] This comparative example provides a gel-type lithium-ion battery, which adopts the same implementation as Example 1, except that the overhang area is 0.1 mm and the injection amount of the precursor electrolyte per Ah is 2 g.

[0078] Table 1 Overhang area and injection amount and polymerizable monomer information in the examples and comparative examples

[0079]

[0080]

[0081] Performance Testing

[0082] The electrochemical performance test and lithium precipitation analysis of the gel-type lithium ion batteries in the examples and comparative examples were performed according to the following methods.

[0083] (1) Fast charging performance test:

[0084] The battery cell is charged and discharged for the first time at a current of 1C (i.e. the current value that completely discharges the theoretical capacity within 1 hour), specifically including: at 25°C, the battery cell is charged at a constant current of 1C to a voltage of 4.4V, then charged at a constant voltage to a current of ≤0.05C, left to stand for 5 minutes, and then discharged at a constant current of 0.33C to a voltage of 2.8V, and its actual capacity is recorded as C0. Then the battery cell is charged at a constant current of 3.0C0, with a charging cut-off voltage of 4.4V, and after each charging is completed, it needs to be discharged at 1C0 to a full battery discharge cut-off voltage of 2.8V.

[0085] (2) Lithium precipitation:

[0086] After completing the fast charge cycle life test, disassemble the battery and observe the lithium deposition around the electrode.

[0087] The test results are shown in Table 2.

[0088] Table 2 Fast charging performance and lithium plating

[0089]

[0090]

[0091] The test results in Table 2 show that reasonable control of the injection volume of the gel electrolyte precursor electrolyte and the distance of the overhang area can reduce lithium plating and improve the fast charge cycle life. At the same time, by reasonably controlling the injection volume of the gel electrolyte, the overhang distance of the positive and negative pole pieces can be effectively reduced to a certain extent, the energy density of the gel lithium-ion battery cell can be improved, and the risk of lithium plating or bulging can be reduced.

[0092] It should be noted that the embodiments of the present invention are only examples to make the technical solution of the present application clearer, and do not mean that the present invention is only applicable to the battery or gel electrolyte type in the present application. The common gel lithium-ion battery compositions in the field can adopt the solution of the present invention and obtain the corresponding technical effects. The specific protection scope shall be subject to the scope of the claims.

[0093] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0094] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A gel-type lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet and a gel electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer formed on the surface of the negative electrode current collector, and the gel electrolyte is formed by an in-situ crosslinking polymerization reaction of a precursor electrolyte, characterized in that: In the gel-type lithium-ion battery, the injection amount of the precursor electrolyte per Ah is recorded as a, and the distance that the edge of at least one side of the negative electrode active material layer exceeds the edge of the positive electrode active material layer is recorded as b, and a and b satisfy 0.3≤a×b≤15.

2. The gel-type lithium ion battery according to claim 1, characterized in that: a and b satisfy 1.0≤a×b≤8.

3. The gel-type lithium ion battery according to claim 1 or 2, characterized in that: A distance b by which an edge of at least one side of the negative electrode active material layer exceeds an edge of the positive electrode active material layer satisfies 0.1 mm≤b≤5 mm.

4. The gel-type lithium ion battery according to claim 1, characterized in that: The precursor electrolyte comprises a basic electrolyte, a polymerizable monomer and an initiator, wherein the basic electrolyte contains an electrolyte lithium salt, an organic solvent and an additive; Preferably, the electrolyte lithium salt is at least one of LiClO4, LiPF6, LiBF4, LiODFB, LiFSI, LiTFSi, LiCF3SO3, LiN(CF3SO2)2, and LiB(C2O4)2; Preferably, the organic solvent is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, methyl butyl carbonate, 1,4-butyrolactone, dimethyltetrahydrofuran, 1,2-dimethoxyethane, methyl acetate, methyl propionate, ethyl propionate, methyl butyrate, trifluoromethylethylene carbonate, dimethyl sulfoxide, cyclopentane, 4-methyl-1,3-butyrolactone, propane sultone, ethylene sulfite, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; Preferably, the additive is at least one of VC, 1,3-PS, LiBOB, VEC, VES, ES, PES, MMDS, DTD, FEC, LiPO2F2, SN, AND, TMSB, TMSP, TMSPi, diphenyldifluorosilane, tris(2,2,2-trifluoroethyl)phosphite, 4-propylvinyl sulfate, tris(2,2,2-trifluoroethyl)phosphite, and diethyl cyanomethyl phosphate.

5. The gel-type lithium ion battery according to claim 4, characterized in that: In the precursor electrolyte, the mass percentage of the polymerizable monomer is 1% to 10%, the mass percentage of the initiator is 0.01% to 0.5%, and the remainder is the basic electrolyte.

6. The gel-type lithium ion battery according to claim 4, characterized in that: In the basic electrolyte, the concentration of the electrolyte lithium salt is 0.7 mol / L to 1.6 mol / L.

7. The gel-type lithium ion battery according to claim 4, characterized in that: In the basic electrolyte, the content of the additive is ≤10wt%.

8. The gel-type lithium ion battery according to claim 4, characterized in that: The polymerizable monomer is at least one of polyethylene glycol diacrylate, tetraethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, and ethoxylated trimethylolpropane triacrylate.

9. The gel-type lithium ion battery according to claim 4, characterized in that: The initiator is a thermal initiator or a photoinitiator; Preferably, the initiator is at least one of 2,2-azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, dodecyl peroxide, diisopropylbenzene peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, and 2-hydroxy-2-methyl-1-phenylacetone.

10. The gel-type lithium ion battery according to claim 1, characterized in that: The gel-type lithium-ion battery is a laminated battery or a wound battery.

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