Whole-domain integrated gel semi-solid battery and preparation method thereof

Abstract

The invention provides a global integrated gel semi-solid battery and a preparation method thereof, and the preparation method comprises the following steps: preparing a pre-semi-solid positive plate and a pre-semi-solid negative plate by using positive slurry and negative slurry containing a grafted prepolymer, coating a diaphragm with the grafted prepolymer slurry, preparing a pre-semi-solid diaphragm, and preparing the global integrated gel semi-solid battery. And assembling the pre-semi-solid positive plate, the pre-semi-solid negative plate and the pre-semi-solid diaphragm into a battery, injecting an electrolyte added with an initiator, sealing, and carrying out in-situ polymerization to obtain the global integrated gel semi-solid battery. A pole piece and electrolyte in the gel semi-solid battery assembled by adopting the method are in a gel state with good uniformity, so that the volume change of an electrode active material in the charge-discharge process can be relieved, the substance migration speed of an electrode interface is reduced, the interface side reaction and the gas production rate in the charge-discharge process are reduced, and the performances such as cycle performance, high temperature and energy storage are improved; and the formed gel electrolyte has relatively high ionic conductivity, so that the rate capability of the battery can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of rechargeable secondary batteries, and in particular relates to a fully integrated gel semi-solid battery and a preparation method thereof. Background Art

[0002] As a high-performance secondary green battery, lithium-ion batteries have the advantages of high voltage, high energy density (including volume energy and mass specific energy), low self-discharge rate, wide operating temperature range, long cycle life, environmental protection, no memory effect, and the ability to charge and discharge at large currents. They are the most promising power batteries in the coming years. However, current commercial lithium-ion secondary batteries mainly use flammable organic carbonate electrolytes, which have great safety risks and cannot meet the higher requirements of current social development for energy storage devices.

[0003] Gel polymer electrolytes (GPEs) have been extensively studied for their potential applications in various electrochemical devices due to their inherent advantages, such as no solvent leakage and no volatility. Furthermore, GPEs have demonstrated superior performance and improved safety compared to commercial liquid electrolytes due to their processability and environmental friendliness.

[0004] However, when gel polymer electrolytes are applied to lithium-ion secondary batteries, insufficient liquid absorption by the gel polymer often results in an excessively high proportion of gel monomers in the overall electrolyte, resulting in low conductivity and reduced battery performance. The biggest obstacle hindering the application of gel polymer electrolytes is battery consistency. Gel monomers are often added to the electrolyte before being injected into the battery. The varying densities of these monomers inevitably lead to sedimentation, resulting in an uneven gel. This in turn leads to low battery yields and inability to guarantee performance.

[0005] Therefore, in order to improve the electrochemical performance and uniformity of gel polymer electrolyte lithium-ion secondary batteries, it is urgent to develop new gel polymer electrolytes with high ionic conductivity and preparation processes. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a fully integrated gel semi-solid battery and a preparation method thereof.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In one aspect, the present invention provides a method for preparing a fully integrated gel semi-solid battery, the method comprising the following steps:

[0009] A pre-semi-solid positive electrode sheet and a pre-semi-solid negative electrode sheet are prepared using a positive electrode slurry and a negative electrode slurry containing a grafted prepolymer, the grafted prepolymer slurry is coated on the separator to prepare a pre-semi-solid separator, and then the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the pre-semi-solid separator are assembled into a battery, an electrolyte added with an initiator is injected, the battery is sealed, and in-situ polymerization is performed to obtain the fully integrated gel semi-solid battery.

[0010] In the present invention, full-domain integration refers to the consistent gelation of the positive electrode, negative electrode and diaphragm of the entire battery. The gel semi-solid battery of the present invention can achieve uniform gelation at the positive electrode, negative electrode and diaphragm, overcoming the problem in the prior art that the grafted prepolymer in the electrolyte cannot maintain its original state during the long-term injection process, and generally micro-polymerization will continue to occur, resulting in the inability to ensure the consistency of the later battery with the earlier battery and the inability to achieve consistent gelation.

[0011] Preferably, the preparation method comprises the following steps:

[0012] S1. Mixing positive electrode slurry 1 with a material containing a grafted prepolymer to obtain positive electrode slurry 2, and preparing a pre-semi-solid positive electrode sheet using positive electrode slurry 2; the grafted prepolymer is at least one compound having a structure shown in Formula I:

[0013]

[0014] wherein R is one or a combination of at least two of a carboxyl group, a ketone group, an ester group, a benzene ring, an alkyl group, an amino group, a four- to twelve-membered cycloalkyl group, a nitrogen heterocycle, a phosphorus heterocycle, or a silicon heterocycle, and n is an integer of 2 to 8;

[0015] S2, mixing the negative electrode slurry 1 with a material containing a grafted prepolymer to obtain a negative electrode slurry 2, and using the negative electrode slurry 2 to prepare a pre-semi-solid negative electrode sheet;

[0016] S3, coating the grafted prepolymer slurry on both surfaces of the diaphragm to prepare a diaphragm sheet;

[0017] S4, assembling a pre-semi-solid positive electrode sheet, a pre-semi-solid negative electrode sheet, and a separator sheet into a battery, injecting an electrolyte, and sealing the battery to obtain a battery, wherein an initiator is added to the electrolyte;

[0018] S5. The battery is polymerized in situ to obtain the fully integrated gel semi-solid battery.

[0019] In the present invention, a gel semi-solid electrode is prepared by adding a grafted prepolymer to the diaphragm and electrode slurry, thereby constructing a gel semi-solid secondary battery. The grafted prepolymer has the characteristics of high conductivity and good oxidative stability, and is designable and multifunctional. It also has the properties of a solid powder, is easily soluble in organic solvents or water, and is easy to apply to the diaphragm and mix in the electrode slurry. Without changing the electrode electrode preparation process, it can further achieve in-situ uniform gelation of the electrode across the entire battery scale, improving the battery's electrochemical performance while increasing consistency and yield. The grafted prepolymer can be well dissolved in the electrolyte. After the battery is filled with electrolyte, the electrolyte at the positive electrode, negative electrode, and diaphragm fully dissolves and diffuses the grafted prepolymer, achieving a uniform dispersion of the grafted prepolymer throughout the battery. After curing, the battery exhibits uniformity as a whole. During the gel polymerization process, the grafted prepolymer composition forms more uniform and abundant nanopores in the electrode, enhancing electrode wetting through the capillary effect, increasing the electrode specific surface area, mass transfer capacity, and electrochemical activity, thereby improving the battery's electrochemical performance. At the electrode, due to the presence of the gel layer, the material migration at the electrode interface is slowed down, the side reactions at the interface are reduced, and various performances such as high temperature and storage are improved; the gel layer at the diaphragm can increase the mechanical strength of the diaphragm and improve battery safety.

[0020] In the present invention, the graft prepolymer is solid powder.

[0021] Preferably, the graft prepolymer is at least one compound having any one of the structures of formula (I-1) to formula (I-4):

[0022]

[0023] In formulas (I-1) to (I-4), R is one or a combination of at least two of a carboxyl group, a keto group, an ester group, a benzene ring, an alkyl group, an amino group, a four- to twelve-membered cycloalkyl group, a nitrogen heterocycle, a phosphorus heterocycle, or a silicon heterocycle;

[0024] Preferably, R is The wavy lines represent the attachment sites of the groups.

[0025] In the present invention, the grafted prepolymer may refer to a single grafted prepolymer or a combination of multiple grafted prepolymers, and the prepolymer skeleton has one or more elements such as carbon, oxygen, hydrogen, silicon, sulfur, nitrogen, phosphorus, fluorine, etc. The prepolymer skeleton may be a linear or cyclic structure.

[0026] Preferably, the graft prepolymer is any one or a combination of at least two of the following compounds:

[0027]

[0028]

[0029] Preferably, the designed electrolyte absorption of the positive electrode sheet is set to account for A% of the total electrolyte, the designed electrolyte absorption of the negative electrode sheet is set to account for B% of the total electrolyte, and the designed electrolyte absorption of the diaphragm sheet is set to account for 100%-B%-A% of the total electrolyte; the amount of the grafted prepolymer in step S1 is 0.9A% to 1.1A% of the total amount of the grafted prepolymer in step S1, step S2 and step S3; the amount of the grafted prepolymer in step S2 is 0.9B% to 1.1B% of the total amount of the grafted prepolymer in step S1, step S2 and step S3; the amount of the grafted prepolymer in step S3 is The total amount of the polymer ranges from (100%-1.1B%-1.1A%) to (100%-0.9B%-0.9A%), for example, it can be 100%-1.1B%-1.1A%, 100%-1.0B%-1.1A%, 100%-1.1B%-1.0A%, 100%-1.0B%-1.0A%, 100%-0.9B%-1.1A%, 100%-0.9B%-1.0A%, 100%-0.9B%-0.9A%, 100%-1.1B%-0.9A%, 100%-1.0B%-0.9A%, 100%-1.1B%-0.9A%, etc.

[0030] Preferably, in step S1 and step S2, the material containing the grafted prepolymer further comprises one or a combination of at least two of a functional additive, a wetting agent and a solvent.

[0031] Preferably, the functional additive is one or a combination of at least two of carbon nanotubes, graphene, phosphate flame retardants, organic or inorganic nitrogen-based flame retardants, two-dimensional materials or inorganic nano-oxide particles.

[0032] Preferably, the two-dimensional material is one or a combination of at least two of carbon nitride (CN), boron nitride (BN), molybdenum disulfide (MoS2), tungsten disulfide (WS2), molybdenum diselenide (MoSe2), tungsten diselenide (WSe2) or MXene.

[0033] Preferably, the wetting agent is one or a combination of at least two of trialkyl phosphate, linear high molecular weight ester, fluorobenzene, phosphorus pentoxide or a high molecular weight copolymer containing an affinity group.

[0034] Preferably, the high molecular copolymer containing affinity groups is one or a combination of at least two of polyacrylate copolymers, polyether copolymers, polyurethane copolymers or silicone copolymers.

[0035] Preferably, the solvent in the material containing the grafted prepolymer in step S1 is a strong polar solvent, preferably NMP or the like.

[0036] Preferably, in step S2, the solvent in the material containing the grafted prepolymer is water.

[0037] Further preferably, in step S1 and step S2, the material containing the grafted prepolymer includes the grafted prepolymer, a functional additive, a wetting agent and a solvent.

[0038] Further preferably, the mass ratio of the grafted prepolymer, the functional additive and the wetting agent in the material containing the grafted prepolymer in step S1 and step S2 is 90-99:1-5:1-5, for example, 90:5:5, 91:5:4, 91:4:5, 92:3:5, 92:4:4, 92:5:3, 93:2:5, 93:3:4, 93:4:3, 93:5:2, 94:1:5, 94:2:4, 94:3:3, 94:4:2, 94:5:1, 95:1:4, 95:2:3, 95:3:2, 95:4:1, 96:1:3, 96:2:2, 96:3:1, 97:1:2, 97:2:1, 98:1:1, etc. Furthermore, the grafted prepolymer-containing material can be added to a solvent (organic solvent or water) in the order of the grafted prepolymer composition, functional additives, and wetting agent, wherein the organic solvent is a highly polar solvent and is volatile. The material is then uniformly mixed by stirring and ultrasonication to form the grafted prepolymer-containing material. The grafted prepolymer-containing material includes a grafted prepolymer solid powder, functional additives, and wetting agent, which can be dissolved in an aqueous or organic solvent. The material is added during the coating process on the diaphragm and the preparation of the electrode slurry. The solvent is evaporated by high-temperature baking without changing the preparation process. Only an appropriate amount of initiator is added during electrolyte injection. High-temperature curing is performed to achieve in-situ gelation of the electrode and battery in a semi-solid state.

[0039] Preferably, in step S1 and step S2, the solid content of the material containing the grafted prepolymer is 10-40%, for example, 10%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 38% or 40%.

[0040] Preferably, the positive electrode slurry 1 in step S1 includes a positive electrode active material, a binder, a conductive agent and a solvent.

[0041] Preferably, the positive electrode active material is selected from lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (LiNiCoMnO2, abbreviated as NCM), lithium nickel cobalt aluminum oxide (LiNiCoAlO2, abbreviated as NCA), lithium iron phosphate (LiFePO4, abbreviated as LFP), etc.

[0042] Preferably, the solvent is selected from N-methylpyrrolidone.

[0043] Preferably, the mass ratio of the positive electrode slurry 1 and the material containing the grafted prepolymer in step S1 is 90-99:1-10, for example, 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3, 98:2 or 99:1.

[0044] Preferably, the process of preparing the pre-semi-solid positive electrode sheet using the positive electrode slurry 2 in step S1 includes coating, drying, slitting, and sheeting.

[0045] Preferably, the negative electrode slurry 1 in step S2 includes a negative electrode active material, a binder, a conductive agent and water.

[0046] Preferably, the negative electrode active material is selected from graphite (such as natural graphite, artificial graphite), silicon-based materials (such as silicon-carbon composite materials, nano-silicon), lithium titanate (Li4Ti5O 12 )wait.

[0047] Preferably, the mass ratio of the negative electrode slurry 1 and the material containing the grafted prepolymer in step S2 is 90-99:1-10, for example, 90:10, 91:9, 92:8, 93:7, 94:6, 95:5, 96:4, 97:3, 98:2 or 99:1.

[0048] Preferably, the process of preparing the pre-semi-solid negative electrode sheet using the negative electrode slurry 2 in step S2 includes coating, drying, slitting, and sheeting.

[0049] Preferably, the graft prepolymer slurry in step S3 comprises a graft prepolymer, a functional additive, a wetting agent and a solvent. The functional additive and the wetting agent are as described above.

[0050] Preferably, the mass ratio of the graft prepolymer, the functional additive and the wetting agent is 90-99:1-5:1-5, for example, 90:5:5, 91:5:4, 91:4:5, 92:3:5, 92:4:4, 92:5:3, 93:2:5, 93:3:4, 93:4:3, 93:5:2, 94:1:5, 94:2:4, 94:3:3, 94:4:2, 94:5:1, 95:1:4, 95:2:3, 95:3:2, 95:4:1, 96:1:3, 96:2:2, 96:3:1, 97:1:2, 97:2:1, 98:1:1, etc., preferably 94-98:1-3:1-3.

[0051] Preferably, in step S3, the grafted prepolymer slurry is coated on both surfaces of the diaphragm, and the diaphragm sheet is prepared by drying and cutting.

[0052] Preferably, the total mass of the grafted prepolymer contained in the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the separator sheet in step S4 accounts for 0.5wt% to 10wt% of the mass of the electrolyte, preferably 0.8wt% to 3wt%, for example, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.2wt%, 2.5wt%, 2.8wt%, 3wt%, etc.

[0053] Preferably, the mass of the initiator described in step S4 is 0.8-5wt% of the total mass of the grafted prepolymer contained in the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the separator sheet, for example, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 2.2wt%, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt% and the like.

[0054] Preferably, the initiator in step S4 is an azo initiator.

[0055] In the present invention, the electrolyte in step S4 can be a conventional liquid electrolyte.

[0056] Preferably, the temperature of the in situ polymerization in step S5 is 50-80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc., and the time of the in situ polymerization is 2-10h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.

[0057] In the present invention, the grafted prepolymer For example, the gel polymerization reaction is shown as follows:

[0058]

[0059] On the other hand, the present invention provides a fully integrated gel semi-solid battery prepared by the preparation method described above.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] In the fully integrated gel semi-solid battery prepared by the preparation method provided by the present invention, the in-situ formed gel semi-solid electrode, diaphragm and semi-solid battery have extremely strong deformation ability, which can alleviate the adverse effects caused by the volume change of the electrode active material during the charging and discharging process. The grafted prepolymer is dispersed in the electrode to make the gel more uniform, and a uniform gel is achieved on the scale of the entire electrode; the in-situ formed gel electrolyte has good uniformity, and has a high ionic conductivity that is only 1-5% lower than that of the basic liquid electrolyte. It is evenly and densely coated on the surface of the electrode active material, thereby improving the rate performance of the battery; and the gel coating slows down the migration of substances at the electrode interface, reduces interfacial side reactions and gas production during charging and discharging, and improves various aspects of high temperature and storage performance; the gel electrolyte mixture will form more uniform and abundant nanopores in the electrode during the gel polymerization process, enhance the electrode infiltration through capillary effect, and increase the electrode specific surface area, mass transfer capacity and electrochemical activity, thereby improving the electrochemical performance of the battery.

[0062] The preparation method provided by the present invention has designable functionality for gel electrolytes, such as flame retardancy, high conductivity, etc., and has better process adaptability and compatibility than solid electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Graph showing the battery cycle capacity test results for Example 1 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0065] The composition of the liquid electrolyte used in the following embodiments and comparative examples is as follows: the volume ratio of EC (ethylene carbonate): EMC (ethylene methyl carbonate): DEC (diethyl carbonate) in the liquid electrolyte is 3:5:2, wherein the concentration of LiPF6 is 1.1 mol / L, the concentration of VC (vinylene carbonate) is 2 wt %, the concentration of PS (polystyrene) is 1 wt %, and the concentration of LiFSI (lithium bis(fluorosulfonyl)imide) is 1 wt %. However, the liquid electrolyte may also be composed of other conventional liquid electrolytes.

[0066] Example 1

[0067] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer is mixed with carbon nanotubes and fluorobenzene in a mass ratio of 98:1:1 to obtain a mixed material.

[0068] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the ternary positive electrode accounted for 10wt% of the total electrolyte, or 0.22g; the liquid absorption of the graphite negative electrode accounted for 50wt% of the total electrolyte, or 1.1g; and the liquid absorption of the separator accounted for 40wt% of the total electrolyte, or 0.88g. Furthermore, the grafted prepolymer accounts for 1wt% of the electrolyte mass, so the amount of grafted prepolymer added to the positive electrode is 0.0022g, the amount of grafted prepolymer added to the negative electrode is 0.011g, and the amount of grafted prepolymer added to the separator is 0.0088g.

[0069] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 1 (solid content of 20%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), and the positive electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid positive electrode sheet;

[0070] Using water as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 2 (solid content of 15%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%), and the negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet;

[0071] Using water as a dispersant, the mixed material and the dispersant are mixed, and dispersed by ultrasonic stirring to obtain a mixed slurry 3 (solid content of 15%); the mixed slurry 3 is coated on a diaphragm, and the diaphragm is dried and cut to obtain a diaphragm sheet;

[0072] The pre-semi-solid positive electrode sheet, pre-semi-solid negative electrode sheet and separator sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 2wt% of the mass of the grafted prepolymer material, that is, 0.00044g.

[0073] After electrolyte injection and sealing, the cell was left to stand at room temperature to allow the grafted prepolymer to fully dissolve in the electrolyte. Appropriate pressure was then applied (0.2 MPa) for 24 hours. After this, the cell was hot-pressed and cured at 1 MPa, 70°C, and 4 hours, resulting in a gel semi-solid electrode and battery. After formation, secondary sealing, and volume separation, its electrochemical performance was tested.

[0074] Example 2

[0075] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer, carbon nanotubes and fluorobenzene are mixed in a mass ratio of 90:9:1 to obtain a mixed material.

[0076] A 0.6Ah graphite / LiCoO2 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. Of this, the positive electrode absorbed 15wt% of the total electrolyte, or 0.33g; the graphite negative electrode absorbed 40wt% of the total electrolyte, or 0.88g; and the separator absorbed 45wt% of the total electrolyte, or 0.99g. Furthermore, the grafted prepolymer accounts for 2wt% of the electrolyte mass, resulting in a total of 0.0066g of grafted prepolymer added to the positive electrode, 0.0176g to the negative electrode, and 0.0198g to the separator.

[0077] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 1 (solid content of 20%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), and the positive electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid positive electrode sheet;

[0078] Using water as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 2 (solid content of 15%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%), and the negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet;

[0079] Using water or NMP as a dispersant, the mixed material and the dispersant are mixed, and dispersed by ultrasonic stirring to obtain a mixed slurry 3 (solid content of 15%); the mixed slurry 3 is coated on a diaphragm, and the diaphragm is dried and cut to obtain a diaphragm sheet;

[0080] The pre-semi-solid positive electrode sheet, pre-semi-solid negative electrode sheet and separator sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 3wt% of the mass of the grafted prepolymer material, i.e. 0.00132g.

[0081] After electrolyte injection and sealing, the battery was left to stand at room temperature and then pressurized to 0.1 MPa for 36 hours. After this, it was hot-pressed to cure at 0.8 MPa, 65°C, and 6 hours, resulting in a gel semi-solid electrode and battery. After formation, secondary sealing, and volume separation, its electrochemical performance was tested.

[0082] Example 3

[0083] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer is mixed with carbon nanotubes and fluorobenzene in a mass ratio of 95:3:2 to obtain a mixed material.

[0084] A 0.6Ah graphite / LiFeO4 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. Of this, the positive electrode absorbed 20% of the total electrolyte, or 0.44g; the graphite negative electrode absorbed 60wt% of the total electrolyte, or 1.32g; and the separator absorbed 20wt% of the total electrolyte, or 0.44g. Furthermore, the grafted prepolymer accounts for 1.5wt% of the electrolyte mass. Therefore, the amount of grafted prepolymer added to the positive electrode is 0.0066g, the amount added to the negative electrode is 0.0198g, and the amount added to the separator is 0.0066g.

[0085] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 1 (solid content of 20%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), and the positive electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid positive electrode sheet;

[0086] Using water as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 2 (solid content of 15%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%), and the negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet;

[0087] Using water or NMP as a dispersant, the mixed material and the dispersant are mixed, and dispersed by ultrasonic stirring to obtain a mixed slurry 3 (solid content of 15%); the mixed slurry 3 is coated on a diaphragm, and the diaphragm is dried and cut to obtain a diaphragm sheet;

[0088] The pre-semi-solid positive electrode sheet, pre-semi-solid negative electrode sheet and separator sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 2.5wt% of the mass of the grafted prepolymer material, that is, 0.000825g.

[0089] After electrolyte injection and sealing, the battery was left to stand at room temperature and then pressurized to 0.3 MPa for 48 hours. After this, it was hot-pressed to cure at 1.2 MPa, 60°C, and 5 hours, resulting in a gel semi-solid electrode and battery. After formation, secondary sealing, and volume separation, its electrochemical performance was tested.

[0090] Example 4

[0091] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer is mixed with carbon nanotubes and fluorobenzene in a mass ratio of 97:2:1 to obtain a mixed material.

[0092] A 0.6Ah silicon-carbon / NCM622 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the ternary positive electrode sheet accounted for 10wt% of the total electrolyte, or 0.22g; the liquid absorption of the silicon-carbon negative electrode sheet accounted for 70wt% of the total electrolyte, or 1.54g; and the liquid absorption of the separator accounted for 20wt% of the total electrolyte, or 0.44g. In addition, the grafted prepolymer accounted for 3wt% of the electrolyte mass. The amount of grafted prepolymer added to the positive electrode was 0.0066g, the amount of grafted prepolymer added to the negative electrode was 0.0462g, and the amount of grafted prepolymer added to the separator was 0.0132g.

[0093] N-methylpyrrolidone (NMP) is used as a dispersant, the mixed material and the dispersant are mixed, and a mixed slurry 1 (solid content of 20%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%). The positive electrode slurry is coated, dried, cut, and sliced to obtain a pre-semi-solid positive electrode sheet.

[0094] Using water as a dispersant, the mixed material and the dispersant are mixed, and a mixed slurry 2 (solid content of 15%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%). The negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet.

[0095] Using water as a dispersant, the mixed material and the dispersant are mixed, and a mixed slurry 3 is obtained by ultrasonic stirring and dispersion; the mixed slurry 3 is coated on the diaphragm, and the diaphragm is dried and cut to obtain a diaphragm sheet.

[0096] The pre-semi-solid positive electrode sheet, pre-semi-solid negative electrode sheet and separator sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 1.5wt% of the mass of the grafted prepolymer material, i.e. 0.00099g.

[0097] After electrolyte injection and sealing, the battery was left to stand at room temperature and then pressurized to 0.3 MPa for 40 hours. After this, it was hot-pressed to cure at 1.3 MPa, 66°C, and 7 hours, resulting in a gel semi-solid electrode and battery. After formation, secondary sealing, and volume separation, its electrochemical performance was tested.

[0098] Example 5

[0099] The only difference between this embodiment and embodiment 1 is that the grafted prepolymer contents of the positive electrode, negative electrode and separator are different, specifically:

[0100] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the ternary positive electrode accounted for 10wt% of the total electrolyte, or 0.22g; the liquid absorption of the graphite negative electrode accounted for 50wt% of the total electrolyte, or 1.1g; and the liquid absorption of the separator accounted for 40wt% of the total electrolyte, or 0.88g. Furthermore, the grafted prepolymer accounts for 1wt% of the electrolyte mass, so the amount of grafted prepolymer added to the positive electrode is 0.00231g, the amount of grafted prepolymer added to the negative electrode is 0.01155g, and the amount of grafted prepolymer added to the separator is 0.00814g.

[0101] Example 6

[0102] The only difference between this embodiment and embodiment 1 is that the grafted prepolymer contents of the positive electrode, negative electrode and separator are different, specifically:

[0103] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the ternary positive electrode accounted for 10wt% of the total electrolyte, or 0.22g; the liquid absorption of the graphite negative electrode accounted for 50wt% of the total electrolyte, or 1.1g; and the liquid absorption of the separator accounted for 40wt% of the total electrolyte, or 0.88g. Furthermore, the grafted prepolymer accounts for 1wt% of the electrolyte mass, so the amount of grafted prepolymer added to the positive electrode is 0.00209g, the amount of grafted prepolymer added to the negative electrode is 0.01067g, and the amount of grafted prepolymer added to the separator is 0.00924g.

[0104] Comparative Example 1 (liquid battery)

[0105] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the positive electrode accounted for 15wt% of the total electrolyte, i.e., 0.33g. The liquid absorption of the graphite negative electrode accounted for 40wt% of the total electrolyte, i.e., 0.88g. The liquid absorption of the separator accounted for 45wt% of the total electrolyte, i.e., 0.99g.

[0106] The positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) is coated, dried, cut and sliced to obtain a positive electrode sheet;

[0107] The negative electrode active slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) is coated, dried, cut and sliced to obtain a negative electrode sheet;

[0108] Cutting the diaphragm into pieces to obtain diaphragm sheets;

[0109] The positive electrode sheet, the negative electrode sheet and the diaphragm sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; wherein no initiator is added to the electrolyte.

[0110] After the electrolyte injection and sealing are completed, let it stand at room temperature and apply appropriate pressure to 0.2MPa for 24h. After standing, hot press it at a pressure of 1MPa and a temperature of 70℃ for 4h. After the second sealing and volume separation, test its electrochemical properties.

[0111] Comparative Example 2 (no grafted prepolymer added to the diaphragm)

[0112] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer is mixed with carbon nanotubes and fluorobenzene in a mass ratio of 98:1:1 to obtain a mixed material.

[0113] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. Of this, the ternary positive electrode absorbed 10wt% of the total electrolyte, or 0.22g; the graphite negative electrode absorbed 50wt% of the total electrolyte, or 1.1g; and the separator absorbed 40wt% of the total electrolyte, or 0.88g. Furthermore, a grafted prepolymer accounted for 1wt% of the electrolyte mass. The amounts of grafted prepolymer added to the positive and negative electrodes were 0.00367g and 0.01833g, respectively; no grafted prepolymer was added to the separator.

[0114] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material and the dispersant are mixed, and ultrasonic stirring and dispersion are performed to obtain a mixed slurry 1 (solid content of 20%); the mixed slurry 1 is mixed with a positive electrode active material slurry (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), and the positive electrode slurry is coated, dried, cut, and sliced to obtain a pre-semi-solid positive electrode sheet;

[0115] Using water as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 2 (solid content of 15%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%), and the negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet;

[0116] The diaphragm is cut into diaphragm sheets;

[0117] The semi-solid positive and negative electrode sheets and the separator sheet are then wound, shelled, grooved, injected with electrolyte, and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 2wt% of the mass of the grafted prepolymer material, i.e. 0.00044g.

[0118] After electrolyte injection and sealing, the battery is left at room temperature and pressurized to 0.2 MPa for 24 hours. After this, it is hot-pressed and cured at 1 MPa, 70°C, and 4 hours. This results in a gel-state battery with semi-solid positive and negative electrodes. After formation, secondary sealing, and capacity separation, its electrochemical performance is tested.

[0119] Comparative Example 3 (grafted prepolymers were added to the positive electrode, negative electrode, and separator, but the proportions of grafted prepolymers at the three locations and the proportions of electrolyte absorption were quite different)

[0120] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer, carbon nanotubes and fluorobenzene are mixed in a mass ratio of 98:1:1 to obtain a mixed material.

[0121] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The ternary positive electrode absorbed 10wt% of the total electrolyte, or 0.22g; the graphite negative electrode absorbed 50wt% of the total electrolyte, or 1.1g; and the separator absorbed 40wt% of the total electrolyte, or 0.88g. Furthermore, 0.0044g of grafted prepolymer was added to the positive electrode; 0.011g to the negative electrode; and 0.0132g to the separator.

[0122] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 1 (solid content of 20%) is obtained by ultrasonic stirring and dispersion; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), and the positive electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid positive electrode sheet;

[0123] Using water as a dispersant, the mixed material and the dispersant are mixed, and the mixed slurry 2 is obtained by ultrasonic stirring and dispersion; the mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, and the solid content is 43.9%) to obtain a negative electrode slurry (solid content 43.9%), and the negative electrode slurry is coated, dried, cut, and sheeted to obtain a pre-semi-solid negative electrode sheet;

[0124] Using water as a dispersant, the mixed material and the dispersant are mixed, and dispersed by ultrasonic stirring to obtain a mixed slurry 3 (solid content of 15%); the mixed slurry 3 is coated on a diaphragm, and the diaphragm is dried and cut to obtain a diaphragm sheet;

[0125] The pre-semi-solid positive electrode sheet, pre-semi-solid negative electrode sheet and separator sheet are then wound, shelled, grooved, injected with electrolyte and sealed to obtain a soft-pack battery cell; the initiator azobisisobutyronitrile (AIBN) is added to the electrolyte, and the added amount is 2wt% of the mass of the grafted prepolymer material, that is, 0.000572g.

[0126] After electrolyte injection and sealing, the battery was left to stand at room temperature and then pressurized to 0.2 MPa for 24 hours. After this, it was hot-pressed to cure at 1 MPa, 70°C, and 4 hours, resulting in a gel semi-solid electrode and battery. After formation, secondary sealing, and volume separation, its electrochemical performance was tested.

[0127] Comparative Example 4 (adding grafted prepolymer and initiator to the positive and negative electrodes and polymerizing them first, and then assembling the battery with the electrolyte)

[0128] N,N'-methylenebisacrylamide (MBA) is used as a solid graft prepolymer, and the solid graft prepolymer is mixed with carbon nanotubes and fluorobenzene in a mass ratio of 98:1:1 to obtain a mixed material.

[0129] A 0.6Ah graphite / NCM811 soft pack was designed with a total liquid electrolyte injection volume of 2.2g. The liquid absorption of the ternary positive electrode accounted for 10wt% of the total electrolyte, i.e., 0.22g; the liquid absorption of the graphite negative electrode accounted for 50wt% of the total electrolyte, i.e., 1.1g; and the liquid absorption of the separator accounted for 40wt% of the total electrolyte, i.e., 0.88g. The grafted prepolymer accounted for 1wt% of the electrolyte mass, and the addition amounts of the grafted prepolymer at the positive and negative electrodes were 0.00367g and 0.01833g, respectively.

[0130] Using N-methylpyrrolidone (NMP) as a dispersant, the mixed material is mixed with the dispersant and initiator azobisisobutyronitrile (AIBN), and dispersed by ultrasonic stirring to obtain a mixed slurry 1 (solid content of 20%), and the added amount of the initiator is 2wt% (0.0000734g) of the weight of the grafted prepolymer; the mixed slurry 1 is mixed with a positive electrode active material slurry (including lithium nickel cobalt manganese oxide (NCM811), PVDF binder, conductive carbon black (the mass ratio of the three is 8:1:1) and NMP, with a solid content of 68.0%) to obtain a positive electrode slurry (solid content of 68%), the positive electrode slurry is coated and dried, and roller pressed at 75°C and 0.5MPa to obtain a positive electrode sheet of a gel electrolyte, which is then cut and sheeted to obtain a positive electrode sheet;

[0131] Using water as a dispersant, the mixed material is mixed with the dispersant and the initiator azobisisobutyronitrile (AIBN), and dispersed by ultrasonic stirring to obtain a mixed slurry 2 (solid content of 15%). The amount of the initiator added is 2 wt% (0.0003666 g) of the grafted prepolymer mass. The mixed slurry 2 is mixed with a negative electrode active material slurry (including graphite, CMC-SBR binder, conductive carbon black (the mass ratio of the three is 8:1:1) and water, with a solid content of 43.9%) to obtain a negative electrode slurry (solid content of 43.9%). The negative electrode slurry is coated and dried, and then rolled at 75°C and 0.5 MPa to obtain a negative electrode sheet of a gel electrolyte. The negative electrode sheet is then cut and sheeted.

[0132] The diaphragm is cut into diaphragm sheets;

[0133] The semi-solid positive and negative electrode sheets and separator sheets are then wound, shelled, grooved, injected with electrolyte, and sealed to obtain soft-pack battery cells; after formation, secondary sealing, and capacity separation, their electrochemical properties are tested.

[0134] All battery tests were completed in the Xinwei test cabinet. The test voltage range was 3.0~4.2V, the test temperature was 60℃, and the test current was 1C. The battery performance is shown in Table 1.

[0135] Figure 1 This is the test chart of capacity retention at 60°C.

[0136] Table 1

[0137]

[0138] As can be seen from Table 1, the capacity retention rates of the in-situ assembled graphite / NCM811 soft-pack batteries in each example were all above 95% after 200 cycles, while in Comparative Example 1, the capacity retention rate was only 25.6% after 39 cycles, and the capacity retention rate of the soft-pack battery in Comparative Example 2 was 63.4% after 200 cycles. This indicates that the in-situ formed gel semi-solid electrode has excellent high-temperature stability, protecting the electrode interface and preventing vigorous reaction between the electrolyte and the active material at high temperatures, thereby effectively improving the high-temperature cycling performance of the battery. It also shows that adding prepolymers to the positive electrode, negative electrode, and separator can improve battery performance.

[0139] As can be seen from Table 1, the impedance, capacity retention rate and capacity recovery rate of the graphite / NCM811 soft-pack battery assembled in Example 1 under the storage conditions are 11.1%, 97.8% and 99.3%, respectively. The impedance of the graphite / NCM811 soft-pack batteries assembled in Example 5 and Example 6 increased under the storage conditions, and the capacity retention rate and capacity recovery rate decreased. The impedance of the graphite / NCM811 soft-pack battery in Comparative Example 3 increased significantly under the storage conditions, and the capacity retention rate and capacity recovery rate also decreased significantly, which reflects the importance of controlling the addition amount of each grafted prepolymer addition position.

[0140] It can be seen from Table 1 that compared with the graphite / NCM811 soft-pack batteries assembled in situ in each embodiment, the battery assembled in situ in comparative example 1 has a significant increase in impedance, and the capacity retention rate and capacity recovery rate are significantly reduced, which shows that the polymer battery assembled by the in situ gel process in the present invention has obvious advantages over the battery assembled by the liquid electrolyte; compared with the graphite / NCM811 soft-pack batteries assembled in situ in each embodiment, the graphite / NCM811 soft-pack batteries assembled in comparative example 4 using in situ gel semi-solid electrodes have increased impedance under the storage conditions, and the capacity retention rate and capacity recovery rate are also significantly reduced, which reflects that the battery assembled by in situ gel after introducing the electrolyte in the present invention has better performance than the battery directly assembled by in situ gel semi-solid electrodes.

[0141] In summary, gel semi-solid batteries assembled by adding an appropriate amount of grafted prepolymer to the positive electrode, negative electrode, and separator, adapted to the liquid absorption amount, can significantly improve the battery's high-temperature cycling and high-temperature storage performance. When the grafted prepolymer is added only to the positive and negative electrodes, the effect of the battery assembled using in-situ polymerization is not significantly improved. The performance of the battery assembled using the electrode pieces prepared using a non-in-situ curing strategy is also significantly inferior to the batteries assembled using in-situ polymerization (Comparative Example 4). Each embodiment designs the amount of grafted prepolymer added at each location based on the liquid absorption amount of the positive, negative electrodes, and separator, and adopts an in-situ gel process, which can better ensure the uniformity of the gel electrolyte electrode size, reduce battery impedance, and improve the overall performance of the battery.

[0142] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the fully integrated gel semi-solid battery and its preparation method, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacement of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a fully integrated gel semi-solid battery, characterized in that: The preparation method comprises the following steps: A pre-semi-solid positive electrode sheet and a pre-semi-solid negative electrode sheet are prepared using a positive electrode slurry and a negative electrode slurry containing a grafted prepolymer, the grafted prepolymer slurry is coated on the separator to prepare a pre-semi-solid separator, and then the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the pre-semi-solid separator are assembled into a battery, an electrolyte added with an initiator is injected, the battery is sealed, and in-situ polymerization is performed to obtain the fully integrated gel semi-solid battery.

2. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: S1. Mixing positive electrode slurry 1 with a material containing a grafted prepolymer to obtain positive electrode slurry 2, and preparing a pre-semi-solid positive electrode sheet using positive electrode slurry 2; the grafted prepolymer is at least one compound having a structure shown in Formula I: wherein R is one or a combination of at least two of a carboxyl group, a ketone group, an ester group, a benzene ring, an alkyl group, an amino group, a four- to twelve-membered cycloalkyl group, a nitrogen heterocycle, a phosphorus heterocycle, or a silicon heterocycle, and n is an integer of 2 to 8; S2, mixing the negative electrode slurry 1 with a material containing a grafted prepolymer to obtain a negative electrode slurry 2, and using the negative electrode slurry 2 to prepare a pre-semi-solid negative electrode sheet; S3, coating the grafted prepolymer slurry on both surfaces of the diaphragm to prepare a diaphragm sheet; S4, assembling a pre-semi-solid positive electrode sheet, a pre-semi-solid negative electrode sheet, and a separator sheet into a battery, injecting an electrolyte, and sealing the battery to obtain a battery, wherein an initiator is added to the electrolyte; S5. The battery is polymerized in situ to obtain the fully integrated gel semi-solid battery.

3. The preparation method according to claim 2, characterized in that The graft prepolymer is at least one compound having any one of the structures of formula (I-1) to formula (I-4): In formulas (I-1) to (I-4), R is one or a combination of at least two of a carboxyl group, a keto group, an ester group, a benzene ring, an alkyl group, an amino group, a four- to twelve-membered cycloalkyl group, a nitrogen heterocycle, a phosphorus heterocycle, or a silicon heterocycle; Preferably, R is The wavy lines represent the attachment sites of the groups; Preferably, the graft prepolymer is any one or a combination of at least two of the following compounds:

4. The preparation method according to any one of claims 1 to 3, characterized in that The designed electrolyte absorption of the positive electrode sheet is set to account for A% of the total electrolyte, the designed electrolyte absorption of the negative electrode sheet is set to account for B% of the total electrolyte, and the designed electrolyte absorption of the diaphragm sheet is set to account for 100%-B%-A% of the total electrolyte; the amount of the grafted prepolymer in step S1 is 0.9A% to 1.1A% of the total amount of the grafted prepolymer in steps S1, S2 and S3; the amount of the grafted prepolymer in step S2 is 0.9B% to 1.1B% of the total amount of the grafted prepolymer in steps S1, S2 and S3; the amount of the grafted prepolymer in step S3 is (100%-1.1B%-1.1A%) to (100%-0.9B%-0.9A%) of the total amount of the grafted prepolymer in steps S1, S2 and S3.

5. The preparation method according to any one of claims 2 to 4, characterized in that In step S1 and step S2, the material containing the grafted prepolymer further comprises one or a combination of at least two of a functional additive, a wetting agent, and a solvent; Preferably, the functional additive is one or a combination of at least two of carbon nanotubes, graphene, phosphate flame retardants, organic or inorganic nitrogen-based flame retardants, two-dimensional materials or inorganic nano-oxide particles; Preferably, the two-dimensional material is one or a combination of at least two of carbon nitride, boron nitride, molybdenum disulfide, tungsten disulfide, molybdenum diselenide, tungsten diselenide or MXene; Preferably, the wetting agent is one or a combination of at least two of trialkyl phosphate, linear polymer ester, fluorobenzene, phosphorus pentoxide or a high molecular weight copolymer containing an affinity group; Preferably, the polymer copolymer containing affinity groups is one or a combination of at least two of polyacrylate copolymers, polyether copolymers, polyurethane copolymers or siloxane copolymers; Preferably, the solvent in the material containing the grafted prepolymer in step S1 is a highly polar solvent, preferably NMP; Preferably, in step S2, the solvent in the material containing the grafted prepolymer is water.

6. The preparation method according to any one of claims 2 to 5, characterized in that In step S1 and step S2, the material containing the grafted prepolymer includes the grafted prepolymer, a functional additive, a wetting agent and a solvent; Further preferably, the mass ratio of the grafted prepolymer, the functional additive and the wetting agent in the material containing the grafted prepolymer in step S1 and step S2 is 90-99:1-5:1-5.

7. The preparation method according to any one of claims 2 to 6, characterized in that In the steps S1 and S2, the solid content of the material containing the grafted prepolymer is 10-40%; Preferably, the positive electrode slurry 1 in step S1 includes a positive electrode active material, a binder, a conductive agent and a solvent; Preferably, the positive electrode active material is selected from lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide or lithium iron phosphate; Preferably, the solvent is selected from N-methylpyrrolidone; Preferably, the mass ratio of the positive electrode slurry 1 and the material containing the grafted prepolymer in step S1 is 90-99:1-10; Preferably, the process of preparing the semi-solid positive electrode sheet using the positive electrode slurry 2 in step S1 includes coating, drying, slitting, and sheeting; Preferably, the negative electrode slurry 1 in step S2 includes a negative electrode active material, a binder, a conductive agent and water. Preferably, the negative electrode active material is selected from graphite, silicon-based materials or lithium titanate; Preferably, the mass ratio of the negative electrode slurry 1 and the material containing the grafted prepolymer mixed in step S2 is 90-99:1-10; Preferably, the process of preparing the pre-semi-solid negative electrode sheet using the negative electrode slurry 2 in step S2 includes coating, drying, slitting, and sheeting; Preferably, the graft prepolymer slurry in step S3 comprises a graft prepolymer, a functional additive, a wetting agent and a solvent; Preferably, the mass ratio of the graft prepolymer, the functional additive and the wetting agent is 90-99:1-5:1-5, preferably 94-98:1-3:1-3; Preferably, in step S3, the grafted prepolymer slurry is coated on both surfaces of the diaphragm, and the diaphragm sheet is prepared by drying and cutting.

8. The preparation method according to any one of claims 2 to 7, characterized in that The total mass of the grafted prepolymer contained in the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the separator sheet in step S4 accounts for 0.5wt% to 10wt% of the mass of the electrolyte; Preferably, the mass of the initiator in step S4 is 0.8 to 5 wt% of the total mass of the grafted prepolymer contained in the pre-semi-solid positive electrode sheet, the pre-semi-solid negative electrode sheet and the separator sheet; Preferably, the initiator in step S4 is an azo initiator.

9. The preparation method according to any one of claims 2 to 8, characterized in that The temperature of the in-situ polymerization in step S5 is 50-80° C., and the time of the in-situ polymerization is 2-10 hours.

10. A fully integrated gel semi-solid battery prepared by the preparation method according to any one of claims 1 to 9.

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