Semi-solid-state battery and preparation method therefor

Abstract

The present invention relates to the technical field of batteries, and provides a semi-solid-state battery and a preparation method therefor. The semi-solid-state battery comprises a battery core and a gel electrolyte. The battery core comprises a positive electrode sheet and a negative electrode sheet, and a three-dimensional network structure coating is disposed on the positive electrode sheet and / or the negative electrode sheet; a preparation raw material of the three-dimensional network structure coating comprises: a fiber material and an initiator; the gel electrolyte is formed by reacting and agglomerating an electrolyte precursor solution and the initiator; the electrolyte precursor solution comprises: a monomer and a crosslinking agent. The semi-solid-state battery has a low resistance, a high specific capacity, a good electrical performance, and a safety performance.

Description

Semi-solid battery and preparation method thereof Technical Field

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

[0002] Currently, commercial secondary batteries typically use liquid electrolytes, which contain large amounts of flammable and easily leakable organic carbonate small molecule solvents, posing significant safety risks. Replacing traditional electrolytes with solid or semi-solid electrolytes effectively avoids electrolyte leakage and volatilization, offering an effective approach to addressing secondary battery safety concerns. Semi-solid / solid electrolytes can generally be categorized as organic polymer electrolytes and inorganic solid electrolytes, further subdivided into solid polymer electrolytes, gel polymer electrolytes, polyelectrolytes, composite polymer electrolytes, and inorganic electrolytes.

[0003] However, it is currently difficult for batteries made with conventional gel electrolytes to achieve the electrical performance level of liquid electrolytes. The main reasons are that the polymerization inside the gel electrolyte is uneven, which obstructs the ion transmission path; and the polymerization inside the battery electrode causes the electron conduction between active materials to be blocked, resulting in rapid performance degradation.

[0004] Therefore, it is of great significance to provide a semi-solid-state battery with uniform gel electrolyte polymerization and excellent electrochemical performance.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a semi-solid-state battery and a preparation method thereof.

[0007] The present invention is achieved through the following technical solutions:

[0008] The present invention provides a semi-solid-state battery, which includes a battery cell and a gel electrolyte. The battery cell includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet and / or the negative electrode sheet are provided with a three-dimensional network structure coating. The raw materials for preparing the three-dimensional network structure coating include: fiber material and initiator; the gel electrolyte is condensed by the reaction of an electrolyte precursor solution and the initiator; the electrolyte precursor solution includes: monomers and a cross-linking agent.

[0009] The coating provided on the electrode of the present invention contains a fiber material that can form a three-dimensional network structure on the surface of the battery electrode. The initiator is anchored inside the three-dimensional network structure through hydrogen bonding. Then, the monomer and cross-linking agent used for thermal polymerization are added to the electrolyte precursor solution, which can react with the initiator at the interface of the battery electrode to form a gel electrolyte, so that the gel electrolyte of the semi-solid battery is uniformly polymerized and has excellent electrochemical performance. The present invention fixes the position of the initiator through the three-dimensional network structure coating to control the polymerization site. On the one hand, it can effectively control the uniformity of the polymerization, preventing the ion transmission channel from being blocked due to uneven polymerization, thereby causing poor electrochemical performance. On the other hand, it can control the polymerization reaction to occur only at the electrode interface, preventing polymerization from occurring inside the electrode and between active particles, resulting in blocked electron conduction between active substances and causing poor kinetic performance.

[0010] As a preferred embodiment of the semi-solid-state battery of the present invention, the three-dimensional network structure coating is prepared by dispersing the fiber material and initiator in solvent I, stirring uniformly to obtain a three-dimensional network structure coating slurry, applying the slurry to the positive electrode sheet and / or the negative electrode sheet, and drying. The mass ratio of the fiber material to the initiator is 1:(0.02-0.3). Preferably, the drying temperature is 60°C-100°C.

[0011] The present invention has found that when the fiber material and initiator are in the above mass ratio, the initiator can be evenly distributed in the three-dimensional network structure coating and firmly anchored, which is conducive to the uniform polymerization of the subsequent gel electrolyte. Furthermore, the mass ratio of fiber material to initiator can be 1:0.02, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, or 1:0.3, but is not limited to these.

[0012] When preparing the three-dimensional network structure coating of the present invention, the type of solvent I is not limited and can be water or an organic solvent. Preferably, the solvent I can be water or N-methylpyrrolidone. In some embodiments, the three-dimensional network structure coating is disposed on the positive electrode sheet, and the solvent I is N-methylpyrrolidone. In some embodiments, the three-dimensional network structure coating is disposed on the negative electrode sheet, and the solvent I is water.

[0013] As a preferred embodiment of the semi-solid-state battery of the present invention, the raw materials for preparing the three-dimensional network structure coating further include ceramic materials. Conventionally, the ceramic materials include at least one of aluminum oxide, titanium dioxide, silicon dioxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, NASICON solid electrolyte, perovskite solid electrolyte, LISICON solid electrolyte, and garnet solid electrolyte; the molecular formula of the NASICON solid electrolyte is Li 1+x Ti 2-x Mx (PO4)3 or Li 1+x Ge 2-x M x (PO4)3, wherein 0.1<x<0.7, M comprises at least one of Al, Ga, In, and Sc; the molecular formula of the perovskite solid electrolyte is Li 3x La (2 / 3)-x TiO3, wherein 0<x<0.16; the molecular formula of the LISICON type solid electrolyte is Li 14 ZnGe4O 16 The molecular formula of the garnet-type solid electrolyte is Li5La3M2O 12 or Li7La3Zr2O 12 , wherein M includes at least one of Ta and Nb.

[0014] In the raw materials for preparing the three-dimensional network coating of the present invention, the mass ratio of the fiber material to the ceramic material can be 1:(0-5), for example, 1:0.1, 1:0.2, 1:0.5, 1:1, 1:2, 1:3, 1:4.

[0015] The coating of the present invention may further include ceramic materials and fiber materials to jointly construct a three-dimensional network framework. The ceramic material may be the aforementioned oxide, hydroxide, or inorganic solid electrolyte. Preferably, when the aforementioned solid electrolyte material is used as the ceramic material and added to the coating, it can effectively increase the rigidity and ionic conductivity of the electrolyte. The rigidity of the electrolyte can effectively prevent the growth of lithium dendrites and the resulting internal short circuits, further improving the safety and electrochemical performance of the battery.

[0016] As a preferred embodiment of the semi-solid-state battery of the present invention, the raw materials for preparing the three-dimensional network structure coating further include a dispersant and a binder; the mass ratio of the fiber material to the dispersant can be 1:(0-0.05), for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04; the mass ratio of the fiber material to the binder can be 1:(0-0.2), for example, 1:0.01, 1:0.02, 1:0.05, 1:0.1, 1:0.15. In some embodiments, in the raw materials for preparing the three-dimensional network structure coating of the present invention, the mass ratio of the fiber material, dispersant, binder, and ceramic material is 1:(0-0.05):(0.01-0.2):(0-5).

[0017] Preferably, the mass ratio of the fiber material, dispersant, binder, and ceramic material is 1:(0.01-0.05):(0.01-0.2):(0.1-5). For example, the mass ratio of the fiber material, dispersant, binder, and ceramic material may be 1:0.01:0.01:0.1, 1:0.02:0.02:0.2, 1:0.02:0.02:0.5, 1:0.01:0.01:1, 1:0.01:0.01:2, 1:0.01:0.01:3, 1:0.01:0.01:4, 1:0.01:0.01:5, 1:0.03:0.1:0.5, 1:0.04:0.2:0.5, or 1:0.05:0.15:0.5, but is not limited thereto.

[0018] Preferably, the preparation method of the three-dimensional network structure coating is: dispersing the fiber material in solvent I, adding other raw materials for preparing the three-dimensional network structure coating, such as the dispersant, binder, ceramic material, and initiator, stirring evenly to obtain a three-dimensional network structure coating slurry, applying it on the positive electrode sheet and / or the negative electrode sheet, and drying it.

[0019] As a preferred embodiment of the semi-solid-state battery of the present invention, at least one of the following is satisfied:

[0020] (1-1) The fiber material comprises at least one of cellulose nanofibers, cellulose nanocrystals, glass fibers, silica nanofibers, silicate fiber materials, polyester fibers, and polyaramid fibers;

[0021] (1-2) the initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethanesulfonate, magnesium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, and tin trifluoromethanesulfonate;

[0022] (1-3) The dispersant comprises at least one of isopropyl alcohol, triolein, oleic acid, terpineol, triethyl phosphate, triethylhexyl phosphate, sodium lauryl sulfate, methylpentyl alcohol, cellulose derivatives, polyacrylamide, and polyethylene glycol esters of fatty acids;

[0023] (1-4) The binder includes at least one of polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile, polyimide, styrene-butadiene rubber, polyacrylic acid, and sodium carboxymethyl cellulose.

[0024] Preferably, the fiber material comprises at least one of cellulose nanofibers, cellulose nanocrystals, polyester fibers and polyaramid fibers.

[0025] When the above-mentioned preferred fiber materials are selected, the semi-solid-state battery can have better electrochemical performance.

[0026] As a preferred embodiment of the semi-solid-state battery of the present invention, the diameter of the fiber material is 50nm-200nm, and the length is 0.5μm-5μm. For example, the diameter of the fiber material can be 50nm, 100nm, 150nm, 200nm, and the length of the fiber material can be 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm. Fiber materials within this diameter and length range can enable semi-solid-state batteries to have better electrochemical performance. If the diameter of the fiber material is too small, it will cause great difficulties in the preparation of the coating; if the diameter of the fiber material is too large, it will not be able to form a three-dimensional network structure at the nanoscale, affecting the anchoring of the initiator in the coating. The fiber material length is within 0.5μm-5μm, which can make the flexibility and entanglement of the fiber material at an appropriate level, thereby realizing a three-dimensional network structure.

[0027] As a preferred embodiment of the semi-solid state battery of the present invention, the thickness of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet or the negative electrode sheet is 3μm-20μm. For example, the thickness of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet or the negative electrode sheet can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm, but is not limited to this.

[0028] As a preferred embodiment of the semi-solid battery of the present invention, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet or the negative electrode sheet is 2 mg / cm 2 -17mg / cm 2 For example, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet or the negative electrode sheet can be 2 mg / cm 2 , 3mg / cm 2 , 4mg / cm 2 , 5mg / cm 2 , 6mg / cm 2 , 7mg / cm 2 , 8mg / cm 2 , 9mg / cm 2 、10mg / cm 2 , 11mg / cm 2 , 12mg / cm 2、13mg / cm 2 、14mg / cm 2 、15mg / cm 2 、16mg / cm 2 or 17 mg / cm 2 , but not limited to this.

[0029] In the present invention, the coating layer having the above-mentioned thickness and coating surface density is selected to ensure the polymerization uniformity of the electrolyte and improve the performance of the battery.

[0030] Preferably, the electrolyte precursor solution further comprises an alkali metal salt, an additive and a solvent II.

[0031] As a preferred embodiment of the semi-solid-state battery of the present invention, the electrolyte precursor solution comprises, by mass percentage, 0.7-1.5 mol / L of alkali metal salt, 0.5%-5% of additives, 3%-7% of monomers and 0.2%-1.5% of cross-linking agent, with the remainder being solvent II. In some embodiments, the concentration of alkali metal salt in the electrolyte precursor solution is 0.7-1.5 mol / L, for example, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L. In some embodiments, the mass percentage of additives in the electrolyte precursor solution is 0.5%-5%, for example, 1%, 2%, 3%, 4%. In some embodiments, the mass percentage of monomers in the electrolyte precursor solution is 3%-7%, for example, 4%, 5%, 6%. In some embodiments, the mass percentage of the cross-linking agent in the electrolyte precursor solution is 0.2%-1.5%, for example, 0.5%, 0.8%, 1%, or 1.2%.

[0032] As a preferred embodiment of the semi-solid-state battery of the present invention, at least one of the following is satisfied:

[0033] (2-1) The solvent II comprises at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, methylpropyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, propyl acetate, γ-butyrolactone, fluoroethylene carbonate, fluoropropylene carbonate, 4-trifluoromethylethylene carbonate, methyl trifluoroethyl carbonate, and bistrifluoroethyl carbonate;

[0034] (2-2) The alkali metal salt includes one of lithium salt, potassium salt and sodium salt;

[0035] (2-3) The additive includes at least one of tris(2,2,2-trifluoroethyl)phosphite, fluoroethylene carbonate, vinylene carbonate, bisfluoroethylene carbonate, vinyl sulfate, 1,3-propylene sultone, and halogenated alkyl phosphate;

[0036] (2-4) The monomers include vinyl acetate, dimethyl allyl malonate, diethyl allyl malonate, methallyl carbonate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, methyl methacrylate, butyl methacrylate, vinylene carbonate, vinyl ethylene carbonate, methyl vinyl sulfone, ethyl vinyl sulfone, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, acrylamide, N,N-methylenebisacrylamide, caprolactam, butyrolactam At least one of amide, maleic anhydride, acrylonitrile, ethyl 2-cyanoacrylate, butyl 2-cyanoacrylate, isooctyl 2-cyano-3,3-diphenylacrylate, 1-cyclohexeneacetonitrile, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, polyethylene glycol methacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxyethyl acrylate, polyethylene glycol, 1,3-dioxolane, dioxane, vinylmethoxysilane, ethyl 2-(trimethylsiloxy)methacrylate, trivinylcyclotrisiloxane, and tris(2-methoxyethoxy)vinylsilane;

[0037] (2-5) The crosslinking agent includes at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, and polyether acrylate.

[0038] As a preferred embodiment of the semi-solid-state battery of the present invention, the battery includes a lithium-ion battery, a sodium-ion battery or a potassium-ion battery.

[0039] As a preferred embodiment of the semi-solid-state battery of the present invention, when the battery is a lithium-ion battery, the alkali metal salt in the electrolyte precursor solution is a lithium salt.

[0040] The lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium nitrate, lithium perchlorate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorobis(oxalatophosphate), lithium tetrafluorooxalatophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl imide) and lithium bis(trifluoromethanesulfonyl imide).

[0041] As a preferred embodiment of the semi-solid-state battery of the present invention, when the battery is a sodium ion battery, the alkali metal salt in the electrolyte precursor solution is a sodium salt.

[0042] As a preferred embodiment of the semi-solid-state battery of the present invention, when the battery is a potassium ion battery, the alkali metal salt in the electrolyte precursor solution is a potassium salt.

[0043] As a preferred embodiment of the semi-solid-state battery of the present invention, the battery is a lithium-ion battery.

[0044] Another object of the present invention is to provide a method for preparing the semi-solid-state battery, comprising the following steps:

[0045] S1. The three-dimensional network structure coating slurry is applied to the surface of the positive electrode and / or negative electrode sheet and dried;

[0046] S2. The positive electrode sheet and the negative electrode sheet obtained in step S1 are made into a battery cell;

[0047] S3. Inject the electrolyte precursor solution into the obtained battery cell, seal it, age it, heat it to 40°C-90°C for thermal polymerization for 20min-48h, cool it down, and let it stand to obtain the semi-solid-state battery.

[0048] The present invention applies a coating containing an initiator and a fiber material to the electrode, which can anchor the initiator in the three-dimensional network structure of the coating, and further reacts the electrolyte precursor solution with the initiator through thermal polymerization to obtain a uniformly polymerized gel electrolyte, thereby improving the electrochemical performance of the battery.

[0049] Preferably, in step S1, the coating method is gravure, transfer, extrusion or spraying; and the drying temperature is 60°C-100°C.

[0050] Preferably, in step S2, the positive electrode sheet, the negative electrode sheet and the separator are formed into a battery cell by lamination or winding.

[0051] Preferably, in step S3, the aging temperature is 40°C-50°C.

[0052] The present invention has the following beneficial effects: the coating provided on the electrode of the present invention contains a fiber material, which can form a three-dimensional network structure on the surface of the battery electrode. The initiator is anchored inside the three-dimensional network structure through hydrogen bonding, controlling the polymerization site. Then, the monomer and cross-linking agent used for thermal polymerization are added to the electrolyte precursor electrolyte, which can react with the initiator to polymerize at the interface of the battery electrode to form a gel electrolyte. On the one hand, the uniformity of the polymerization can be effectively controlled to prevent the obstruction of ion transmission channels caused by uneven polymerization, thereby causing poor electrochemical performance. On the other hand, the polymerization reaction can be controlled to occur only at the electrode interface, preventing polymerization from occurring inside the electrode and between active particles, resulting in obstruction of electronic conduction between active substances and causing poor kinetic performance. The semi-solid-state battery of the present invention has low resistance, high specific capacity, and good electrical and safety performance. DETAILED DESCRIPTION

[0053] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0054] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0055] The silicon-carbon negative electrode active material used in the examples and comparative examples was purchased from Lanxi Zhide New Energy Materials Co., Ltd. with the brand name S0332. The perovskite-type solid electrolyte lanthanum lithium titanate powder (LLTO) used in the examples and comparative examples was purchased from Blue Good New Energy Co., Ltd. with the brand name LG1522. The NASICON-type solid electrolyte powder lithium aluminum titanium phosphate (LATP) used in the examples and comparative examples was purchased from B&T New Materials Group Co., Ltd. with the brand name BEO-1S.

[0056] Example 1

[0057] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive and negative electrode sheets, wherein the negative electrode sheet is provided with a three-dimensional network structure coating; the preparation method of the semi-solid lithium-ion battery is as follows:

[0058] S1. Preparation of positive electrode: LiNi 0.8 Co 0.1 Mn 0.1 The positive electrode active material O2 (NCM811), the conductive carbon black (sp) as a conductive agent, the conductive carbon nanotubes as a conductive agent, and the binder polyvinylidene fluoride are uniformly mixed in N-methylpyrrolidone at a mass ratio of 96:2:0.5:1.5 to form a positive electrode slurry. The positive electrode slurry is coated on one side of the current collector aluminum foil, dried and rolled at 120°C, and then the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with the positive electrode active material layer coated on both sides is then cold pressed; after trimming and cutting, the positive electrode sheet of the lithium-ion battery is made;

[0059] S2. Preparation of a three-dimensional network coating slurry: 0.3 kg of cellulose nanofibers, 6 g of triethyl phosphate (dispersant) and 0.03 kg of styrene-butadiene rubber (SBR) binder were added to 3.5 kg of deionized water, and after stirring, 30 g of azobisisobutyronitrile initiator was added and stirred again to obtain a three-dimensional network coating slurry; the diameter of the fiber material cellulose nanofiber was 50-100 nm and the length was 0.5 μm-2 μm;

[0060] S3. Preparation of negative electrode sheet: Silicon-carbon negative electrode active material, conductive agent SP, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber are mixed uniformly in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry, which is coated on one side of the current collector copper foil and dried and rolled at 105°C. The negative electrode slurry is then coated and dried on the other side of the copper foil according to the above method. The prepared copper foil with the negative electrode active material layer on both sides is then cold pressed to obtain a negative electrode sheet;

[0061] S4. Setting a three-dimensional network structure coating on the negative electrode sheet: Then, the three-dimensional network structure coating slurry prepared in S2 is applied to the negative electrode active material layer on both sides of the negative electrode sheet obtained in S3 by a transfer coater. The drying temperature is 85°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 7.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 102 μm is produced;

[0062] S5. Preparation of battery cells: A 9 μm thick polyethylene porous film was selected as a separator. The positive electrode sheet, separator, and negative electrode sheet having a three-dimensional network structure coating were wound into a battery cell. The battery cell capacity was approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets. The positive electrode was spot-welded to an aluminum tab, and the negative electrode was spot-welded to a nickel tab.

[0063] S6. Prepare an electrolyte precursor solution: The reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) are stirred for 4 hours and added to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1), and then lithium hexafluorophosphate (LiPF6) and an additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) are added and stirred thoroughly; in the electrolyte precursor solution, the content of the reaction monomer is 5wt%; the content of the cross-linking agent is 1.2wt%; the concentration of LiPF6 is 1mol / L, the content of the additive is 5wt%, and the balance is solvent;

[0064] S7. Prepare the battery: Place the battery cell obtained in step S5 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 40°C, heat to 60°C for thermal polymerization for 12h, cool to 40°C and let stand to obtain the semi-solid lithium-ion battery.

[0065] Example 2

[0066] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive and negative electrode sheets, wherein the negative electrode sheet is provided with a three-dimensional network structure coating. The preparation method of the semi-solid lithium-ion battery is as follows:

[0067] S1. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotube, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry, the positive electrode slurry is coated on one side of the current collector aluminum foil, and after drying and rolling at 120°C, the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed; after trimming and cutting, the lithium-ion battery positive electrode sheet is produced;

[0068] S2. Preparation of three-dimensional network structure coating slurry: 0.3 kg cellulose nanofibers, 0.15 kg perovskite solid electrolyte lithium lanthanum titanate powder (LLTO, Li 3x La (2 / 3)x TiO3), 6g triethyl phosphate and 0.03kg styrene-butadiene rubber (SBR) binder, after fully stirring, 30g azobisisobutyronitrile initiator was added, and stirred again to obtain a three-dimensional network structure coating slurry; the fiber material cellulose nanofiber has a diameter of 50nm-100nm and a length of 0.5μm-2μm;

[0069] S3. Preparation of negative electrode sheet: Silicon-carbon negative electrode active material, conductive agent SP, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber are mixed uniformly in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry. The slurry is applied to one side of the current collector copper foil and dried at 105°C. The negative electrode slurry is then applied to the other side of the copper foil and dried according to the above method. The prepared copper foil with the negative electrode active material layer on both sides is then cold pressed to obtain a negative electrode sheet.

[0070] S4. Setting a three-dimensional network structure coating on the negative electrode sheet: Then, the prepared three-dimensional network structure coating slurry is applied to the negative electrode active material layer on both sides of the negative electrode sheet through a transfer coater for a second coating. The drying temperature is 95°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 9.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 102 μm is produced;

[0071] S5. Preparation of battery cells: A 9 μm thick polyethylene porous film was selected as a separator. The positive electrode sheet, separator, and negative electrode sheet having a three-dimensional network structure coating were wound into a battery cell. The battery cell capacity was approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets. The positive electrode was spot-welded to an aluminum tab, and the negative electrode was spot-welded to a nickel tab.

[0072] S6. Prepare an electrolyte precursor solution: The reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) are stirred for 4 hours and added to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1), and then lithium hexafluorophosphate (LiPF6) and an additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) are added and stirred thoroughly; in the electrolyte precursor solution, the content of the reaction monomer is 5wt%; the content of the cross-linking agent is 1.2wt%; the concentration of LiPF6 is 1mol / L, the content of the additive is 5wt%, and the balance is solvent;

[0073] S7. Prepare the battery: Place the battery cell obtained in step S5 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 50°C, heat to 60°C for 12h, cool to 50°C and let stand to obtain the semi-solid lithium-ion battery.

[0074] Example 3

[0075] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet is provided with a three-dimensional network structure coating. The preparation method of the semi-solid lithium-ion battery is as follows:

[0076] S1. Preparation of a three-dimensional network structure coating slurry: 0.3 kg of cellulose nanocrystals, 6 g of triethyl phosphate and 0.03 kg of polyvinylidene fluoride (PVDF) binder were added to 3.5 kg of N-methylpyrrolidone (NMP), stirred thoroughly, and then 30 g of azobisisobutyronitrile initiator was added and stirred again to obtain a three-dimensional network structure coating slurry; the diameter of the fiber material cellulose nanocrystals was 50 nm-100 nm and the length was 0.5 μm-2 μm;

[0077] S2. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotubes, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry. The positive electrode slurry is coated on one side of the current collector aluminum foil, dried and rolled at 120°C, and then the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed to obtain a positive electrode sheet;

[0078] S3. Setting a three-dimensional network structure coating on the positive electrode sheet: The prepared three-dimensional network structure coating slurry is then applied to the positive electrode active material layer on both sides of the positive electrode sheet using a transfer coater. The drying temperature is 85°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 7.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery positive electrode sheet with a total thickness of 127 μm is produced;

[0079] S4. Prepare the negative electrode sheet: Mix the silicon-carbon negative electrode active material, the conductive agent SP, the thickener sodium carboxymethyl cellulose, and the binder styrene-butadiene rubber in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry, apply it on one side of the current collector copper foil, dry and roll it at 105°C, and then apply the negative electrode slurry on the other side of the copper foil and dry it according to the above method. Then, cold press the prepared copper foil with the negative electrode active material layer on both sides; trim and cut the pieces to make the lithium-ion battery negative electrode sheet;

[0080] S5. Preparation of battery cells: A polyethylene porous film with a thickness of 9 μm was selected as a separator. The positive electrode sheet, separator, and negative electrode sheet provided with the three-dimensional network structure coating were wound into a battery cell. The battery cell capacity was approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets. The positive electrode was spot-welded to an aluminum tab, and the negative electrode was spot-welded to a nickel tab.

[0081] S6. Prepare an electrolyte precursor solution: The reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) are stirred for 4 hours and added to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1), and then lithium hexafluorophosphate (LiPF6) and an additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) are added and stirred thoroughly; in the electrolyte precursor solution, the content of the reaction monomer is 5wt%; the content of the cross-linking agent is 1.2wt%; the concentration of LiPF6 is 1mol / L, the content of the additive is 5wt%, and the balance is solvent;

[0082] S7. Prepare the battery: Place the battery cell obtained in step S5 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 40°C, heat to 60°C for thermal polymerization for 12h, cool to 40°C and let stand to obtain the semi-solid lithium-ion battery.

[0083] Example 4

[0084] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet is provided with a three-dimensional network structure coating. The preparation method of the semi-solid lithium-ion battery is as follows:

[0085] S1. Preparation of three-dimensional network structure coating slurry: 0.3 kg polyester fiber, 0.15 kg NASICON solid electrolyte powder lithium aluminum titanium phosphate (LATP, Li 1+x Ti2 -x Al x (PO4) 3), 6g of triethyl phosphate and 0.03kg of polyvinylidene fluoride (PVDF) binder are fully stirred, and then 30g of azobisisobutyronitrile initiator is added and stirred again to obtain a three-dimensional network structure coating slurry; the polyester fiber has a diameter of 50nm-100nm and a length of 0.5μm-2μm;

[0086] S2. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotubes, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry. The positive electrode slurry is coated on one side of the current collector aluminum foil, dried and rolled at 120°C, and then the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed to obtain a positive electrode sheet;

[0087] S3. Setting a three-dimensional network structure coating on the positive electrode sheet: Then the prepared three-dimensional network structure coating slurry is applied to the positive electrode active material layer on both sides of the positive electrode sheet through a transfer coater for a second coating. The drying temperature is 95°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 9.3mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery positive electrode sheet with a total thickness of 127 μm is produced;

[0088] S4. Prepare the negative electrode sheet: Mix the silicon-carbon negative electrode active material, the conductive agent SP, the thickener sodium carboxymethyl cellulose, and the binder styrene-butadiene rubber in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry, apply it on one side of the current collector copper foil, dry and roll it at 105°C, and then apply the negative electrode slurry on the other side of the copper foil and dry it according to the above method. Then, cold press the prepared copper foil with the negative electrode active material layer on both sides; trim and cut the pieces to make the lithium-ion battery negative electrode sheet;

[0089] S5. Preparation of battery cells: A polyethylene porous film with a thickness of 9 μm was selected as a separator. The positive electrode sheet, separator, and negative electrode sheet with a three-dimensional network structure coating were wound into a battery cell. The battery cell capacity was approximately 10 Ah. The separator was located between adjacent positive and negative electrodes. The positive electrode was spot-welded to an aluminum tab and the negative electrode was spot-welded to a nickel tab.

[0090] S6. Prepare an electrolyte precursor solution: The reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) are stirred for 4 hours and added to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1), and then lithium hexafluorophosphate (LiPF6) and an additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) are added and stirred thoroughly; in the electrolyte precursor solution, the content of the reaction monomer is 5wt%; the content of the cross-linking agent is 1.2wt%; the concentration of LiPF6 is 1mol / L, the content of the additive is 5wt%, and the balance is solvent;

[0091] S7. Prepare the battery: Place the battery cell obtained in step S5 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 40°C, heat to 60°C for thermal polymerization for 12h, cool to 40°C and let stand to obtain the semi-solid lithium-ion battery.

[0092] Example 5

[0093] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive and negative electrode sheets, wherein the negative electrode sheet is provided with a three-dimensional network structure coating; the preparation method of the semi-solid lithium-ion battery is as follows:

[0094] S1. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotube, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry, the positive electrode slurry is coated on one side of the current collector aluminum foil, and after drying and rolling at 120°C, the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed; after trimming and cutting, the lithium-ion battery positive electrode sheet is produced;

[0095] S2. Preparation of a three-dimensional network coating slurry: 0.3 kg of cellulose nanofibers, 6 g of triethyl phosphate and 0.03 kg of styrene-butadiene rubber (SBR) binder were added to 3.5 kg of deionized water, stirred thoroughly, and then 30 g of azobisisobutyronitrile initiator was added and stirred again to obtain a three-dimensional network coating slurry; the diameter of the fiber material cellulose nanofiber was 100 nm-200 nm and the length was 2 μm-5 μm;

[0096] S3. Preparation of negative electrode sheet: Silicon-carbon negative electrode active material, conductive agent SP, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber are mixed uniformly in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry, which is coated on one side of the current collector copper foil and dried and rolled at 105°C. The negative electrode slurry is then coated and dried on the other side of the copper foil according to the above method. The prepared copper foil with the negative electrode active material layer on both sides is then cold pressed to obtain a negative electrode sheet;

[0097] S4. Setting a three-dimensional network structure coating on the negative electrode sheet: Then, the prepared three-dimensional network structure coating slurry is applied to the negative electrode active material layer on both sides of the negative electrode sheet through a transfer coater for a second coating. The drying temperature is 85°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 11 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 9 μm; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 105 μm is produced;

[0098] S5. Preparation of battery cells: A 9 μm thick polyethylene porous film was selected as a separator. The positive electrode sheet, separator, and negative electrode sheet having a three-dimensional network structure coating were wound into a battery cell. The battery cell capacity was approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets. The positive electrode was spot-welded to an aluminum tab, and the negative electrode was spot-welded to a nickel tab.

[0099] S6. Prepare an electrolyte precursor solution: The reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) are stirred for 4 hours and added to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1), and then lithium hexafluorophosphate (LiPF6) and an additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) are added and stirred thoroughly; in the electrolyte precursor solution, the content of the reaction monomer is 5wt%; the content of the cross-linking agent is 1.2wt%; the concentration of LiPF6 is 1mol / L, the content of the additive is 5wt%, and the balance is solvent;

[0100] S7. Preparation of battery: The battery cell obtained in step S5 is placed in an aluminum-plastic packaging bag, baked, and then injected with the above-mentioned electrolyte precursor solution, sealed, formed, aged at 40°C, heated to 60°C for thermal polymerization for 12h, cooled to 40°C and allowed to stand, thereby obtaining the semi-solid lithium-ion battery.

[0101] Example 6

[0102] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte. The battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are both provided with a three-dimensional network structure coating. The preparation method of the semi-solid lithium-ion battery is as follows:

[0103] S1. Preparation of a three-dimensional network structure coating slurry for the positive electrode: 0.3 kg of cellulose nanofibers, 6 g of triethyl phosphate, and 0.03 kg of polyvinylidene fluoride (PVDF) binder were added to 3.5 kg of N-methylpyrrolidone (NMP), stirred thoroughly, and then 30 g of azobisisobutyronitrile initiator was added and stirred again to obtain a three-dimensional network structure coating slurry; the diameter of the cellulose nanofibers of the fiber material was 50 nm-100 nm and the length was 0.5 μm-2 μm;

[0104] S2. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotubes, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry. The positive electrode slurry is coated on one side of the current collector aluminum foil, dried and rolled at 120°C, and then the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed to obtain a positive electrode sheet;

[0105] S3. Setting a three-dimensional network structure coating on the positive electrode sheet: Then, the three-dimensional network structure coating slurry prepared in S1 is applied to the positive electrode active material layer on both sides of the positive electrode sheet through a transfer coater. The drying temperature is 85°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 15 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 12 μm; after trimming and cutting, a lithium-ion battery positive electrode sheet with a total thickness of 127 μm is produced;

[0106] S4. Preparation of a three-dimensional network coating slurry for the negative electrode: 0.3 kg of cellulose nanofibers, 6 g of triethyl phosphate, and 0.03 kg of styrene-butadiene rubber (SBR) binder were added to 3.5 kg of deionized water, stirred thoroughly, and then 30 g of azobisisobutyronitrile initiator was added and stirred again to obtain a three-dimensional network coating slurry; the diameter of the fiber material cellulose nanofiber was 50 nm-100 nm and the length was 0.5 μm-2 μm;

[0107] S5. Prepare the negative electrode sheet: Mix the silicon-carbon negative electrode active material, conductive agent SP, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry. Apply the slurry to one side of the current collector copper foil and dry it at 105°C before rolling it up. Then, apply the negative electrode slurry to the other side of the copper foil and dry it as described above. The prepared copper foil with the negative electrode active material layer on both sides is then cold pressed.

[0108] S6. Setting a three-dimensional network structure coating on the negative electrode sheet: Then, the three-dimensional network structure coating slurry prepared in S4 is applied to the negative electrode active material layer on both sides of the negative electrode sheet by a transfer coater. The drying temperature is 85°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 7.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 102 μm is produced;

[0109] S7. Preparation of a battery cell: A polyethylene porous film having a thickness of 9 μm was selected as a separator, and the positive electrode sheet having a three-dimensional network structure coating obtained in S3, the separator, and the negative electrode sheet having a three-dimensional network structure coating obtained in S6 were wound into a battery cell having a battery capacity of approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets, and the positive electrode was spot-welded to an aluminum tab and the negative electrode was spot-welded to a nickel tab;

[0110] S8. Prepare an electrolyte precursor solution: Add the reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1) after being fully stirred for 4 hours. Then, add lithium hexafluorophosphate (LiPF6) and the additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) and stir thoroughly. In the electrolyte precursor solution, the content of the reaction monomer is 5 wt%; the content of the cross-linking agent is 1.2 wt%; the concentration of LiPF6 is 1 mol / L, the content of the additive is 5 wt%, and the balance is solvent.

[0111] S9. Prepare the battery: Place the battery cell obtained in step S7 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal it, form it, age it at 40°C, heat it to 60°C for thermal polymerization for 12h, cool it to 40°C and let it stand, to obtain the semi-solid lithium-ion battery.

[0112] Example 7

[0113] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte. The battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are both provided with a three-dimensional network structure coating. The preparation method of the semi-solid lithium-ion battery is as follows:

[0114] S1. Preparation of positive electrode three-dimensional network structure coating slurry: 0.3 kg polyaramid fiber, 0.15 kg NASICON solid electrolyte powder lithium aluminum titanium phosphate (LATP, Li 1+x Ti 2-x Al x (PO4) 3), 6g of triethyl phosphate and 0.03kg of polyvinylidene fluoride (PVDF) binder are fully stirred, and then 30g of azobisisobutyronitrile initiator is added and stirred again to obtain a three-dimensional network structure coating slurry; the diameter of the polyaramid fiber is 50nm-100nm and the length is 0.5μm-2μm;

[0115] S2. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotubes, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry. The positive electrode slurry is coated on one surface of the current collector aluminum foil, dried and rolled at 120°C, and then the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed to obtain a positive electrode sheet;

[0116] S3. Setting a three-dimensional network structure coating on the positive electrode sheet: The three-dimensional network structure coating slurry prepared in S1 is then applied to the positive electrode active material layer on both sides of the positive electrode sheet using a transfer coater. The drying temperature is 95°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the positive electrode sheet is 9.3 mg / cm 2 The thickness of the three-dimensional network structure coating on one side of the positive electrode sheet in the thickness direction is 6 μm; after trimming and cutting, a lithium-ion battery positive electrode sheet with a total thickness of 127 μm is produced;

[0117] S4. Preparation of a three-dimensional network structure coating slurry for the negative electrode: 0.3 kg of polyaramid fiber, 0.15 kg of perovskite-type solid electrolyte lanthanum titanate lithium powder (LLTO, Li 3x La (2 / 3)-x TiO3), 6g triethyl phosphate and 0.03kg styrene-butadiene rubber (SBR) binder, after fully stirring, 30g azobisisobutyronitrile initiator was added, and stirred again to obtain a three-dimensional network structure coating slurry; the diameter of the polyaramid fiber was 50nm-100nm, and the length was 0.5μm-2μm;

[0118] S5. Prepare the negative electrode sheet: Mix the silicon-carbon negative electrode active material, conductive agent SP, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry. Apply the slurry to one side of the current collector copper foil and dry it at 105°C before rolling it up. Then, apply the negative electrode slurry to the other side of the copper foil and dry it according to the above method. Then, cold press the prepared copper foil with the negative electrode active material layer on both sides.

[0119] S6. Setting a three-dimensional network structure coating on the negative electrode sheet: Then, the three-dimensional network structure coating slurry prepared in S4 is applied to the negative electrode active material layer on both sides of the negative electrode sheet by a transfer coater. The drying temperature is 95°C. After drying, the coating surface density of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 9.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 6 μm; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 102 μm is produced;

[0120] S7. Preparation of a battery cell: A polyethylene porous film having a thickness of 9 μm was selected as a separator, and the positive electrode sheet having a three-dimensional network structure coating of the above S3, the separator, and the negative electrode sheet having a three-dimensional network structure coating of S6 were wound into a battery cell having a battery capacity of approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets, the positive electrode was spot-welded to an aluminum tab, and the negative electrode was spot-welded to a nickel tab;

[0121] S8. Prepare an electrolyte precursor solution: Add the reaction monomer vinylene carbonate (VC) and the cross-linking agent polyethylene glycol diacrylate (PEGDA) to a solvent (the solvent formula is a mixed solution of propylene carbonate (PC): ethylene carbonate (EC): dimethyl carbonate (DMC) with a volume ratio of 1:1:1) after being fully stirred for 4 hours. Then, add lithium hexafluorophosphate (LiPF6) and the additive tris(2,2,2-trifluoroethyl) phosphite (TTFP) and stir thoroughly. In the electrolyte precursor solution, the content of the reaction monomer is 5 wt%; the content of the cross-linking agent is 1.2 wt%; the concentration of LiPF6 is 1 mol / L, the content of the additive is 5 wt%, and the balance is solvent.

[0122] S9. Prepare the battery: Place the battery cell obtained in step S7 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal it, form it, age it at 40°C, heat it to 60°C for thermal polymerization for 12h, cool it to 40°C and let it stand, to obtain the semi-solid lithium-ion battery.

[0123] Example 8

[0124] The difference between the preparation method of this embodiment and that of Example 2 is that, in the preparation process of the three-dimensional network structure coating, an equal amount of glass fibers are used to replace the cellulose nanofibers. The rest is the same as that of Example 2, and the semi-solid lithium-ion battery of this embodiment is prepared.

[0125] Example 9

[0126] The difference between the preparation method of this embodiment and that of Example 2 is that, during the preparation of the three-dimensional network structure coating, the amount of initiator added is 6 g, and the rest is the same as that of Example 2, to prepare the semi-solid lithium ion battery of this embodiment.

[0127] Example 10

[0128] The difference between the preparation method of this embodiment and that of Example 2 is that, during the preparation of the three-dimensional network structure coating, the amount of initiator added is 90 g, and the rest is the same as that of Example 2, to prepare the semi-solid lithium ion battery of this embodiment.

[0129] Example 11

[0130] The difference between the preparation method of this embodiment and that of Example 2 is that, during the preparation of the three-dimensional network structure coating, the amount of initiator azobisisobutyronitrile added is 3 g, and the rest is the same as in Example 2, to prepare a semi-solid lithium-ion battery.

[0131] Example 12

[0132] The difference between the preparation method of this embodiment and that of Example 2 is that, during the preparation of the three-dimensional network structure coating, the amount of initiator azobisisobutyronitrile added is 120 g, and the rest is the same as in Example 2, to prepare a semi-solid lithium-ion battery.

[0133] Example 13

[0134] The difference between the preparation method of this embodiment and that of embodiment 2 is that the coating surface density of the three-dimensional network structure coating on one side after drying is 1.5 mg / cm 2 , and the thickness of the three-dimensional network structure coating on one side is 2 μm; the rest are the same as in Example 2, and a semi-solid lithium-ion battery is prepared.

[0135] Example 14

[0136] The difference between the preparation method of this embodiment and that of embodiment 2 is that the coating surface density of the three-dimensional network structure coating on one side after drying is 25 mg / cm 2 , and the thickness of the three-dimensional network structure coating on one side is 20 μm; the rest are the same as in Example 2, and a semi-solid lithium-ion battery is prepared.

[0137] Comparative Example 1

[0138] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator spaced between the positive electrode sheet and the negative electrode sheet. The preparation method of the semi-solid lithium-ion battery is as follows:

[0139] S1. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotube, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry, the positive electrode slurry is coated on one side of the current collector aluminum foil, and after drying and rolling at 120°C, the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method. The prepared aluminum foil with a positive electrode active material layer on both sides is then cold pressed; after trimming and cutting, the lithium-ion battery positive electrode sheet is produced;

[0140] S2. Preparation of negative electrode sheet: Silicon-carbon negative electrode active material, conductive agent conductive carbon black (sp), thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber are mixed uniformly in a mass ratio of 96:1.5:1.0:1.5 in deionized water to form a negative electrode slurry, which is coated on one side of the current collector copper foil and dried and rolled at 105°C. The negative electrode slurry is then coated and dried on the other side of the copper foil according to the above method. The prepared copper foil with a negative electrode active material layer on both sides is then cold pressed; after trimming and cutting, a lithium-ion battery negative electrode sheet with a total thickness of 102μm is produced;

[0141] S3. Preparation of battery cells: A polyethylene porous film having a thickness of 9 μm was selected as a separator, and the positive electrode sheet, separator, and negative electrode sheet were wound into a battery cell having a battery capacity of approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets, and the positive electrode was spot-welded to an aluminum tab and the negative electrode was spot-welded to a nickel tab;

[0142] S4. Preparation of an electrolyte precursor solution: The preparation of the electrolyte precursor solution in this comparative example is the same as in Example 1, except that 30 g of azobisisobutyronitrile is additionally added to the electrolyte precursor solution, wherein the electrolyte precursor solution contains azobisisobutyronitrile in an amount of 10 wt %;

[0143] S5. Prepare the battery: Place the battery cell obtained in step S3 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 40°C, heat to 60°C for thermal polymerization for 12h, cool to 40°C and let stand to obtain the semi-solid lithium-ion battery.

[0144] Comparative Example 2

[0145] A semi-solid lithium-ion battery comprises a battery cell and a gel electrolyte. The battery cell comprises a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive and negative electrode sheets. The negative electrode sheet is provided with a three-dimensional network structure coating, and the coating does not contain an initiator. The preparation method of the semi-solid lithium-ion battery is as follows:

[0146] S1. Preparation of positive electrode sheet: NCM811 positive electrode active material, conductive agent SP, conductive agent carbon nanotubes, and binder polyvinylidene fluoride are mixed uniformly in a mass ratio of 96:2:0.5:1.5 in N-methylpyrrolidone to form a positive electrode slurry, the positive electrode slurry is coated on one side of the current collector aluminum foil, and after drying and rolling at 120°C, the positive electrode slurry is coated and dried on the other side of the aluminum foil according to the above method, and then the prepared aluminum foil with a positive electrode active material layer on both sides is cold pressed; after trimming, cutting, and slitting, a lithium-ion battery positive electrode sheet is produced;

[0147] S2. Preparation of negative electrode sheet: Preparation of three-dimensional network structure coating: 0.3kg cellulose nanofibers, 6g triethyl phosphate and 0.03kg styrene-butadiene rubber (SBR) binder were added to 3.5kg deionized water and stirred thoroughly to obtain a three-dimensional network structure coating slurry; the fiber material cellulose nanofibers had a diameter of 50-100nm and a length of 0.5μm-2μm;

[0148] The silicon-carbon negative electrode active material, conductive agent sp, thickener sodium carboxymethyl cellulose, and binder styrene-butadiene rubber were mixed evenly in deionized water at a mass ratio of 96:1.5:1.0:1.5 to form a negative electrode slurry, which was coated on one side of the current collector copper foil and dried and rolled at 105°C. The negative electrode slurry was then coated and dried on the other side of the copper foil according to the above method. The prepared copper foil with a negative electrode active material layer on both sides was cold pressed to obtain a negative electrode sheet. The prepared three-dimensional network structure coating slurry was then coated twice on both sides of the negative electrode sheet by a transfer coater. The drying temperature was 85°C. The surface density of the three-dimensional network structure coating after drying was 7.3 mg / cm 2 The thickness of the three-dimensional network structure coating on either side of the thickness direction of the negative electrode sheet is 6 μm; after trimming, cutting, and slitting, a lithium-ion battery negative electrode sheet with a total thickness of 102 μm is produced;

[0149] S3. Preparation of battery cells: A polyethylene porous film having a thickness of 9 μm was selected as a separator, and the positive electrode sheet, separator, and negative electrode sheet were wound into a battery cell having a battery capacity of approximately 10 Ah. The separator was located between adjacent positive and negative electrode sheets, and the positive electrode was spot-welded to an aluminum tab and the negative electrode was spot-welded to a nickel tab;

[0150] S4. Preparation of an electrolyte precursor solution: The preparation of the electrolyte precursor solution in this comparative example is the same as in Example 1, except that 30 g of azobisisobutyronitrile is additionally added to the electrolyte precursor solution, wherein the electrolyte precursor solution contains azobisisobutyronitrile in an amount of 10 wt %;

[0151] S5. Prepare the battery: Place the battery cell obtained in step S3 in an aluminum-plastic packaging bag, inject the above-mentioned electrolyte precursor solution after baking, seal, form, age at 40°C, heat to 60°C for thermal polymerization for 12h, cool to 40°C and let stand to obtain the semi-solid lithium-ion battery.

[0152] Comparative Example 3

[0153] The difference between the preparation method of this comparative example and that of Example 1 is that cellulose nanofibers are not added during the preparation of the three-dimensional network structure coating. The rest is the same as that of Example 1, and a semi-solid lithium-ion battery is prepared.

[0154] Performance test: The following tests were performed on the semi-solid lithium-ion batteries prepared in the above examples and comparative examples:

[0155] Specific capacity test: fully charge to 4.2V at 0.33C constant voltage and constant current to 0.05C, and discharge to 2.5V at 1C to obtain the discharge capacity; the discharge capacity is then divided by the mass of the positive electrode active material (the positive electrode active material is the material in the positive electrode active layer except the conductive agent and the binder. For example, for Example 1, the mass of the positive electrode active material is the mass of NCM811) to obtain the specific capacity.

[0156] First-effect test: fully charge the battery to 4.2V at 0.33C constant voltage and constant current (CVCC) to 0.05C to obtain the charge capacity. Then discharge the battery to 2.5V at 1C to obtain the discharge capacity. The ratio of the discharge capacity to the charge capacity is the first-effect test.

[0157] DC internal resistance test: fully charge the battery to 4.2V at 0.33C constant voltage and constant current (CVCC) to 0.05C, then discharge it at 2C for 30s. Subtract the voltage after 30s of discharge from the voltage before 30s to get the voltage difference. Then divide the voltage difference by the discharge current to get the DC internal resistance.

[0158] Needle penetration test: A needle penetration test is conducted on a safety testing machine. Specifically, a 5mm to 8mm high-temperature resistant steel needle (the cone angle of the needle tip is 45° to 60°, and the surface of the needle is smooth, free of rust, oxide layer and oil) is used to penetrate the battery at a speed of 25mm / s in a direction perpendicular to the large surface of the battery. The penetration position should be close to the geometric center of the punctured surface, and the steel needle should remain in the battery. The absence of smoke and fire is used as the criterion for passing the needle penetration test.

[0159] The results of the above tests are shown in Table 1.

[0160] Table 1 Electrical and safety performance test results of the embodiments and comparative examples

[0161] As can be seen from Table 1, the semi-solid batteries of Examples 1-10 of the present invention have good electrical properties and safety performance. In Comparative Example 1, the safety of the semi-solid battery is significantly reduced due to the lack of a three-dimensional network structure coating. In Comparative Example 2, the initiator is placed in the electrolyte solution, and the degree of coagulation of the gel electrolyte cannot be effectively controlled, resulting in a decrease in the electrical performance and safety of the semi-solid battery. In Comparative Example 3, no fiber material is added to the coating, and the initiator cannot be anchored in the coating. The electrical performance of the semi-solid battery is significantly reduced, and the safety performance is simultaneously reduced.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A semi-solid battery, comprising a battery cell and a gel electrolyte, wherein the battery cell comprises a positive electrode sheet and a negative electrode sheet, characterized in that: The positive electrode sheet and / or the negative electrode sheet is provided with a three-dimensional network structure coating; the raw materials for preparing the three-dimensional network structure coating include: fiber material and initiator; the gel electrolyte is condensed by the reaction of an electrolyte precursor solution and the initiator; the electrolyte precursor solution includes: a monomer and a cross-linking agent.

2. The semi-solid-state battery according to claim 1, characterized in that: The preparation method of the three-dimensional network structure coating is: disperse the fiber material and the initiator in solvent I, stir evenly and then apply them on the positive electrode sheet and / or the negative electrode sheet, and dry them; the mass ratio of the fiber material to the initiator is 1: (0.02-0.3).

3. The semi-solid-state battery according to claim 1, characterized in that: The raw materials for preparing the three-dimensional network structure coating also include ceramic materials.

4. The semi-solid-state battery according to claim 3, characterized in that: The raw materials for preparing the three-dimensional network structure coating also include a dispersant and a binder; the mass ratio of the fiber material, the dispersant, the binder, and the ceramic material is 1: (0-0.05): (0.01-0.2): (0-5).

5. The semi-solid-state battery according to claim 4, characterized in that: The semi-solid-state battery satisfies at least one of the following: (1-1) The fiber material comprises at least one of cellulose nanofibers, cellulose nanocrystals, glass fibers, silica nanofibers, silicate fiber materials, polyester fibers, and polyaramid fibers; (1-2) the initiator includes at least one of azobisisobutyronitrile, azobisisoheptylnitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, stannous octoate, lithium acetate, triethyl phosphine, triphenyl phosphine, tri-n-butyl phosphine, tributyltin oxide, tetrabutyl titanate, tetrabutyl zirconate, trialkyltin alkoxide, dialkyltin oxide, N-methylethylenediamine, dimethylformamide, triethyleneethylenediamine, methyldiethylene glycolamine, triethylenediamine, aluminum trifluoromethanesulfonate, magnesium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide and tin trifluoromethanesulfonate; (1-3) The dispersant includes isopropyl alcohol, triolein, oleic acid, terpineol, triethyl phosphate, triethylhexyl phosphate, sodium lauryl sulfate, methyl amyl alcohol, cellulose derivatives, polyacrylamide At least one of an amine and a fatty acid polyethylene glycol ester; (1_4) The binder includes at least one of polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile, polyimide, styrene-butadiene rubber, polyacrylic acid, and sodium carboxymethyl cellulose.

6. The semi-solid-state battery according to claim 1, characterized in that: The fiber material has a diameter of 50 nm to 200 nm and a length of 0.5 μm to 5 μm.

7. The semi-solid-state battery according to claim 1, characterized in that: The thickness of the three-dimensional network structure coating on either side of the positive electrode sheet or the negative electrode sheet in the thickness direction is 3 μm-20 μm, and the coating surface density of the three-dimensional network structure coating on either side of the positive electrode sheet or the negative electrode sheet in the thickness direction is 2 mg / cm 2 -17mg / cm 2 .

8. The semi-solid-state battery according to claim 1, characterized in that: The electrolyte precursor solution also includes an alkali metal salt, an additive and a solvent II; in terms of mass percentage, the electrolyte precursor solution includes: 0.7-1.5 mol / L of an alkali metal salt, 0.5%-5% of an additive, 3%-7% of a monomer and 0.2%-1.5% of a cross-linking agent, and the remainder is solvent II.

9. The semi-solid-state battery according to claim 8, characterized in that: The semi-solid-state battery satisfies at least one of the following: (2-1) the solvent II comprises at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, methylpropyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl butyrate, propyl acetate, γ-butyrolactone, fluoroethylene carbonate, fluoropropylene carbonate, 4-trifluoromethylethylene carbonate, methyl trifluoroethyl carbonate and bistrifluoroethyl carbonate; (2-2) The alkali metal salt includes one of a lithium salt, a potassium salt and a sodium salt; (2-3) The additive includes at least one of tris(2,2,2-trifluoroethyl)phosphite, fluoroethylene carbonate, vinylene carbonate, bisfluoroethylene carbonate, vinyl sulfate, 1,3-propylene sultone, and halogenated alkyl phosphate; (2-4) The monomers include vinyl acetate, dimethyl allyl malonate, diethyl allyl malonate, methallyl carbonate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, methyl methacrylate, butyl methacrylate, vinylene carbonate, vinylethylene carbonate, methyl vinyl sulfone, ethyl vinyl sulfone, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, acrylamide, N,N-methylenebisacrylamide, caprolactam, butyrolactam, maleic anhydride, acrylonitrile, At least one of 2-cyanoacrylate ethyl, 2-cyano-2-acrylate butyl, 2-cyano-3,3-diphenylacrylate isooctyl, 1-cyclohexeneacetonitrile, hexafluorobutyl methacrylate, trifluoroethyl methacrylate, polyethylene glycol methacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, ethoxyethyl acrylate, polyethylene glycol, 1,3-dioxolane, dioxane, vinylmethoxysilane, 2-(trimethylsiloxy)ethyl methacrylate, trivinylcyclotrisiloxane, and tris(2-methoxyethoxy)vinylsilane; (2-5) The crosslinking agent includes at least one of polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, and polyether acrylate.

10. The method for preparing a semi-solid-state battery according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Applying the three-dimensional network structure coating slurry on the surface of the positive electrode sheet and / or the negative electrode sheet and drying; S2. The positive electrode sheet and the negative electrode sheet obtained in step S1 are made into a battery cell; S3. Inject the electrolyte precursor solution into the obtained battery cell, seal it, age it, heat it to 40°C-90°C for thermal polymerization for 20min-48h, cool it down, and let it stand to obtain the semi-solid-state battery.

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