Energy storage device, method for manufacturing the same, and production system thereof

Abstract

The present invention relates to an energy storage device, a method for manufacturing the same, and a production system thereof. The energy storage device includes: a porous separator impregnated with a non-aqueous liquid electrolyte or a gel electrolyte, or a solid-state electrolyte; a positive electrode active material layer coated on one side of the separator or solid-state electrolyte; a negative electrode active material layer coated on a side of the separator or solid-state electrolyte opposite to the positive electrode active material layer; a positive electrode current collector deposited on the positive electrode active material layer; and a negative electrode current collector deposited on the negative electrode active material layer.

Description

Technical Field

[0001] This invention relates generally to the field of electrochemistry, and particularly to the field of energy storage. Specifically, this invention relates to energy storage devices such as secondary batteries, including lithium-ion secondary batteries, methods for their preparation, and production systems thereof. Background Technology

[0002] In recent years, with the large-scale application of energy storage devices such as lithium-ion batteries, increasingly higher demands have been placed on them. For example, the market demand for high-performance, high-capacity energy storage devices such as lithium-ion batteries is growing. To increase the capacity of energy storage devices such as lithium-ion batteries, higher-capacity active materials are typically used, or the amount of active material loaded is increased (i.e., the amount used per unit area, in other words, the active material layer is made thicker). However, when the amount of active material used per unit area is increased, and thus the thickness of the active material layer increases, the specific capacity and cycle performance of energy storage devices such as lithium-ion batteries decrease significantly, especially under high-rate charge and discharge conditions.

[0003] To meet the growing demand for high-performance, high-capacity energy storage devices, such as secondary batteries like lithium-ion secondary batteries, it is urgent to develop a new type of energy storage device, such as a new type of secondary battery like lithium-ion secondary batteries. Summary of the Invention

[0004] This invention was made in view of the above-mentioned problems existing in the prior art.

[0005] In a first aspect, the present invention relates to an energy storage device, such as a secondary battery like a lithium-ion secondary battery, comprising...

[0006] Porous membranes impregnated with non-aqueous liquid electrolytes or gel electrolytes, or solid electrolytes;

[0007] A positive electrode active material layer is coated on one side of the separator or solid electrolyte;

[0008] A negative electrode active material layer is coated on the side of the separator or solid electrolyte opposite to the positive electrode active material layer;

[0009] Positive current collector, which is deposited on the positive active material layer; and

[0010] The negative electrode current collector is deposited on the negative electrode active material layer.

[0011] In a second aspect, the present invention relates to a method for manufacturing an energy storage device, such as a secondary battery like a lithium-ion secondary battery, according to the first aspect of the invention, comprising:

[0012] (1) Provide a porous membrane and a non-aqueous liquid electrolyte or gel electrolyte, or provide a solid electrolyte;

[0013] (2) Provide a positive electrode slurry including a positive electrode active material and a negative electrode slurry including a negative electrode active material;

[0014] (3) Simultaneously or in any order, the positive electrode slurry is coated on one side of the separator or solid electrolyte, and the negative electrode slurry is coated on the side of the separator or solid electrolyte opposite to the positive electrode slurry, and then dried;

[0015] (4) Deposit a positive current collector on the obtained positive electrode active material layer, and deposit a negative current collector on the obtained negative electrode active material; and

[0016] (5) The product obtained in step (4) is contained in a battery package, wherein, if a separator is used, a non-aqueous liquid electrolyte or a gel electrolyte is injected into the product obtained in step (4).

[0017] In a third aspect, the present invention relates to a production system for manufacturing energy storage devices, such as secondary batteries like lithium-ion secondary batteries, according to the first aspect of the invention, comprising:

[0018] (a) A mixing device that mixes raw materials to obtain a positive electrode slurry or a negative electrode slurry;

[0019] (b) A coating apparatus that coats a positive or negative electrode slurry from a mixing device onto a separator or solid electrolyte;

[0020] (c) A drying apparatus for drying a slurry coated on the diaphragm or the solid electrolyte to obtain a positive electrode active material layer and / or a negative electrode active material layer;

[0021] (d) A rolling device for rolling a positive electrode active material layer or a negative electrode active material layer; and

[0022] (e) A current collector deposition apparatus, wherein the current collector deposition apparatus deposits a positive current collector or a negative current collector on the positive or negative electrode active material layer.

[0023] The cell structure of this invention can significantly reduce the volume and mass proportion of auxiliary components (such as sheet-like current collectors for coating active materials) in the battery, thereby increasing the specific capacity and volumetric capacity of energy storage devices, such as secondary batteries like lithium-ion secondary batteries. Furthermore, in addition to the increase in specific capacity due to the reduction in the mass and volume of auxiliary components, the inventors, after extensive research, discovered that compared to conventional energy storage devices such as lithium-ion secondary batteries that coat positive and negative electrode active materials onto the positive and negative electrode current collectors, and energy storage devices such as lithium-ion secondary batteries that coat active materials only on one side of the separator and deposit current collectors, and attach the other side of the separator to the current collector coated with active materials, and energy storage devices such as lithium-ion secondary batteries that coat positive and negative electrode active materials on both sides of the separator and then attach conventional sheet-like current collectors, the energy storage device of this invention exhibits better electrochemical performance, especially at higher active material loadings.

[0024] This invention improves the specific capacity and cycle performance of energy storage devices, such as secondary batteries like lithium-ion batteries, by coating positive and negative electrode active materials onto a separator and then depositing current collectors on the positive and negative electrode active material layers. Further research by the inventors revealed that this improvement is more pronounced when the amount of active material loaded is increased; furthermore, even with increased charge / discharge rates, the improvement remains significant with increased active material loading, which is beneficial for improving the specific capacity and cycle performance of lithium-ion batteries under high-rate conditions; and even with increased active material loading and increased charge / discharge rates, the improvement remains significant with increased cycle counts. Compared to existing technologies, the energy storage devices of this invention, such as secondary batteries like lithium-ion batteries, achieve improved specific capacity and cycle performance by increasing the amount of active material per unit area to increase capacity, thus better meeting market demands. Attached Figure Description

[0025] To more clearly illustrate the technical solution of the present invention, the accompanying drawings required for describing the embodiments will be briefly described below. It should be understood that these drawings are only for the purpose of facilitating a better understanding of the present invention by those skilled in the art, and are not intended to limit the scope of the present invention.

[0026] Figure 1 This is a schematic diagram of the structure of a secondary battery, such as a lithium-ion secondary battery, according to the present invention.

[0027] Figure 2 For the batteries of embodiments 1-3 according to the present invention, at 1mAh / cm 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0028] Figure 3For the batteries of embodiments 4-6 according to the present invention, at 2mAh / cm 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0029] Figure 4 For the batteries of embodiments 7-9 according to the present invention, at 3mAh / cm 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0030] Figure 5 For the battery of embodiments 7'-9' according to the present invention, at 3mAh / cm 2 A graph showing the loading of positive electrode active material and the specific capacity at a rate of 1.0C versus the number of cycles.

[0031] Figure 6 According to embodiments 10-12 of the present invention, the battery has a capacity of 3 mAh / cm². 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0032] Figure 7 According to embodiments 13-15 of the present invention, the battery has a capacity of 3 mAh / cm². 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0033] Figure 8 For the batteries of embodiments 16-18 according to the present invention, at 3mAh / cm 2 The graph shows the loading of the positive electrode active material and the specific capacity at a rate of 0.4C versus the number of cycles.

[0034] Figure 9 This is a schematic diagram of a production system for an energy storage device, such as a secondary battery or a lithium-ion secondary battery, according to the present invention. Detailed Implementation

[0035] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, this application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages described in this application can be compatible and / or combined together.

[0036] Unless otherwise specified, the technical terms used in this specification have the same meaning as commonly understood by those skilled in the art.

[0037] This invention relates to energy storage devices, such as secondary batteries like lithium-ion secondary batteries, their preparation methods, and production systems.

[0038] The present invention will be described in detail below.

[0039] Energy storage devices

[0040] In a first aspect, the present invention relates to an energy storage device, such as a secondary battery like a lithium-ion secondary battery, comprising...

[0041] Porous membranes impregnated with non-aqueous liquid electrolytes or gel electrolytes, or solid electrolytes;

[0042] A positive electrode active material layer is coated on one side of the separator or solid electrolyte;

[0043] A negative electrode active material layer is coated on the side of the separator or solid electrolyte opposite to the positive electrode active material layer;

[0044] Positive current collector, which is deposited on the positive active material layer; and

[0045] The negative electrode current collector is deposited on the negative electrode active material layer.

[0046] Compared to traditional energy storage devices such as lithium-ion batteries, which coat positive and negative electrode active materials onto the current collectors, and energy storage devices such as lithium-ion batteries that coat active materials and deposit current collectors only on one side of the separator and attach the other side of the separator to the current collector coated with active materials, and energy storage devices that coat positive and negative electrode active materials on both sides of the separator and then attach conventional sheet-like current collectors, by coating both positive and negative electrode active materials onto the separator and then depositing current collectors on the positive and negative electrode active material layers, the specific capacity and cycle performance of energy storage devices such as lithium-ion batteries can be improved. Further research by the inventors revealed that the improvement is more pronounced when the active material loading is increased; furthermore, with increased active material loading, the improvement remains significant even with further increases in charge / discharge rate, which is beneficial for improving the specific capacity and cycle performance of energy storage devices such as lithium-ion batteries under high-rate conditions; and further still, with increased active material loading and increased charge / discharge rate, the improvement remains significant even with increased cycle count. Compared to existing technologies, the energy storage devices of the present invention, such as secondary batteries like lithium-ion secondary batteries, have improved specific capacity and cycle performance when increasing capacity by increasing the amount of active material per unit area, which helps to better meet market demands.

[0047] In some embodiments, the energy storage device is a lithium-ion secondary battery, a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor, preferably a lithium-ion secondary battery, a sodium-ion secondary battery, or a lithium-sulfur secondary battery.

[0048] The energy storage device of the present invention will be described below using a lithium-ion secondary battery as an example. Those skilled in the art will readily understand that the sodium-ion secondary battery, lithium-sulfur secondary battery, and capacitor of the present invention can be obtained by referring to the description of lithium-ion secondary batteries and making appropriate adjustments.

[0049] Lithium-ion secondary batteries

[0050] In some embodiments, the energy storage device of the present invention is a lithium-ion secondary battery.

[0051] This invention does not have any particular requirements on the type of diaphragm, and any diaphragm conventionally used in the art can be used. In some embodiments, the diaphragm may be selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyamide, and poly(p-phenylene terephthalamide).

[0052] This invention does not have any particular requirements regarding the type of non-aqueous liquid electrolyte. The non-aqueous liquid electrolyte includes organic solvents and lithium electrolyte salts.

[0053] In some embodiments, the organic solvent may be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0054] In some embodiments, the electrolyte lithium salt may be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroborate (LiBF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0055] In some embodiments, the concentration of lithium ions in the non-aqueous liquid electrolyte is 0.5 to 1.5 mol / L, for example 0.8 to 1.2 mol / L.

[0056] In some embodiments, the non-aqueous liquid electrolyte may optionally include additives. As an example, the additives may include those that facilitate film formation on the negative electrode or the positive electrode, and may also include additives that improve battery performance, such as those that improve the battery's high-temperature or low-temperature performance.

[0057] This invention does not place particular emphasis on the type of gel electrolyte; any gel electrolyte conventionally used in the art can be employed. In some embodiments, the gel electrolyte is selected from one or more of polyvinylidene fluoride (PVDF), vinylidene fluoride hexafluoropropylene copolymer P (VDFHFP), polyethylene oxide (PEO), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). Furthermore, it will be readily understood by those skilled in the art that the gel electrolyte of this invention may also include a lithium salt, as described above regarding lithium salts in non-aqueous liquid electrolytes.

[0058] This invention does not have any particular requirements regarding the type of solid electrolyte; any solid electrolyte conventionally used in the art can be employed. The solid electrolyte can be selected from one or more of inorganic solid electrolytes or polymer electrolytes, preferably from one or more of oxides, sulfides, and polymers. For example, the solid electrolyte can be selected from lithium garnet oxide (Li7La3Zr2O). 12 One or more of the following: lithium oxide (LLZO), tin oxide (SnO2), bismuth oxide (Bi2O3), lithium sulfide (Li2S), sodium sulfide (Na2S), silicates, phosphates, siloxanes, perovskite oxides, lithium oxides, and polymer solid electrolytes.

[0059] This invention does not impose any particular requirement on the type of positive electrode active material, and any positive electrode active material commonly used in the art can be used. In some embodiments, the positive electrode active material is selected from, for example, one or more of lithium transition metal composite oxides, and composite oxides obtained by adding other transition metals, non-transition metals, or non-metals to lithium transition metal composite oxides. In some embodiments, the layered transition metal oxide may have the general formula Li x M y O2, wherein M is selected from one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg, and the general formula satisfies valence equilibrium. Furthermore, the layered transition metal oxide may be doped with elements with high electronegativity, such as one or more of S, N, F, Br, Cl, I, and CN. For example, the positive electrode active material may be selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphates with an olivine structure, such as LiMn2O4, LiNiMnCoO2, and LiNiO5Co. 0.3 Mn0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi1 / 3Co1 / 3Mn1 / 3O2, LiFePO4, LiNiCoAlO2 and Li2TiO, etc.

[0060] In some embodiments, the content of the positive electrode material, based on the total weight (dry weight) of the positive electrode active material layer, can be a commonly used amount in the art, for example, 70-99% by weight, or 80-90% by weight.

[0061] In some embodiments, the positive electrode active material layer may also include a binder, a conductive agent, and optional other additives such as thickeners.

[0062] In some embodiments, the positive electrode binder is selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), waterborne acrylic resin, and sodium carboxymethyl cellulose (CMC-Na).

[0063] In some embodiments, the content of the positive electrode binder may be 0.5-15.0% by weight, for example 2.0-5.0% by weight, based on the total weight (dry weight) of the positive electrode active material.

[0064] In some embodiments, the positive electrode conductive agent may be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0065] In some embodiments, the content of the positive electrode conductive agent may be 0.5-15.0% by weight, for example 2.0-5.0% by weight, based on the total weight (dry weight) of the positive electrode active material.

[0066] In some embodiments, the thickener may be selected from sodium carboxymethyl cellulose, etc.

[0067] In some embodiments, the content of the thickener may be 0.2-4.0% by weight, for example 0.2-2.5% by weight, based on the total weight (dry weight) of the positive electrode active material.

[0068] In some embodiments, any negative electrode active material commonly used by those skilled in the art can be employed. For example, the negative electrode active material may be one or more of natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate, and metallic sodium, preferably one or more of graphite and silicon-based materials, and more preferably one or more of graphite, silicon-carbon composites, and silicon alloys.

[0069] In some embodiments, the content of the negative electrode material, based on the total weight (dry weight) of the negative electrode active material layer, can be a commonly used amount in the art, for example, 70-99% by weight, or 80-90% by weight.

[0070] In some embodiments, the negative electrode active material layer may also include binders, conductive agents, etc.

[0071] In some embodiments, the negative electrode binder is not particularly required. As an example, the negative electrode binder is selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), waterborne acrylic resin, and sodium carboxymethyl cellulose (CMC-Na).

[0072] In some embodiments, the content of the negative electrode binder may be 0.5-15.0% by weight, for example 2.0-5.0% by weight, based on the total weight (dry weight) of the negative electrode active material layer.

[0073] In some embodiments, the negative electrode conductive agent is not particularly required. As an example, the negative electrode conductive agent may be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0074] In some embodiments, the content of the negative electrode conductive agent may be 0.5-15.0% by weight, for example 2.0-5.0% by weight, based on the total weight (dry weight) of the negative electrode active material layer.

[0075] In some embodiments, the positive electrode current collector material may be a conductive material suitable for the deposition process and meeting the requirements of the chemical and electrochemical environment on the positive electrode side of the battery, such as an alloy formed of one or more elements such as aluminum, nickel, iron, and carbon.

[0076] In some embodiments, the negative electrode current collector material may be a conductive material suitable for the deposition process and meeting the requirements of the chemical and electrochemical environment on the negative electrode side of the battery, such as an alloy formed of one or more elements such as copper, nickel, iron, and carbon.

[0077] In some embodiments, the loading of the positive electrode active material is 0.5-5.0 mAh / cm³. 2 For example, 1.0-3.0 mAh / cm³ 2 In this invention, the term "capacity" refers to the capacity (mAh / cm²) of the positive or negative electrode active material carried per unit area, calculated according to theoretical capacity. 2This can also be referred to as "area capacity." For example, the loading of the positive electrode active material can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mAhh / cm³. 2 Within the range defined by , or any two of them.

[0078] In some embodiments, the loading of the negative electrode active material is 0.5-5.0 mAh / cm³. 2 For example, 1.0-3.0 mAh / cm³ 2 As an example, the loading of the negative electrode active material can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mAhh / cm³. 2 Within the range defined by , or any two of them.

[0079] In some embodiments, the thickness of the positive electrode current collector is 0.5-5.0 μm. Those skilled in the art will readily understand that, in this invention, the positive electrode current collector may be continuous or discrete. In this invention, the thickness of the positive electrode current collector can be measured and calculated by subtracting the thickness of the positive electrode active material layer before current collector deposition from the sum of the thickness of the positive electrode active material layer after current collector deposition and the thickness of the positive electrode current collector. As an example, the thickness of the positive current collector can be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 μm, or within the range defined by any two of these.

[0080] In some embodiments, the thickness of the negative current collector is 0.5-5.0 μm. Those skilled in the art will readily understand that the thickness of the negative current collector can be measured or calculated in a similar and / or in the same manner as the thickness of the positive current collector. As an example, the thickness of the positive current collector can be within the range defined by 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 μmm, or any two of these.

[0081] In some embodiments, the diaphragm or solid electrolyte further includes a surface coating, which comprises one or more of alumina, hydrated alumina, attapulgite, aramid, carbon nanotubes, graphene, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), aqueous acrylic resin, and sodium carboxymethyl cellulose (CMC-Na).

[0082] The energy storage device of the present invention has been described above using a lithium-ion secondary battery as an example. Those skilled in the art will readily understand that the energy storage device of the present invention can also be a sodium-ion secondary battery, a lithium-sulfur secondary battery, or a capacitor. Furthermore, those skilled in the art can refer to the lithium-ion secondary battery described above and make appropriate adjustments to obtain the sodium-ion secondary battery, lithium-sulfur secondary battery, or capacitor of the present invention.

[0083] In some embodiments, the energy storage device of the present invention is a sodium-ion secondary battery. When the energy storage device is a sodium-ion secondary battery, the positive electrode active material is selected from one or more of layered transition metal oxides or Prussian blue analogues, preferably one or more of NaNi1 / 3Fe1 / 3Mn1 / 3O2, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), Na3V2(PO4)3, NaFePO4, and NaMnFe(CN)6; and / or the negative electrode active material is selected from one or more of natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon-based materials, and tin-based materials, preferably one or more of graphite and silicon-based materials, and more preferably one or more of graphite, silicon-carbon composites, and silicon alloys.

[0084] In some embodiments, the energy storage device of the present invention is a lithium-sulfur secondary battery. When the energy storage device is a lithium-sulfur secondary battery, the positive electrode active material is selected from one or more of inorganic compounds such as lithium sulfide, titanium sulfide, and phosphorus sulfide, or organic compounds having straight-chain alkyl, branched-chain alkyl, cycloalkanes, aromatics, or heteroatom-containing aromatics combined with sulfur, preferably one or more of sulfur-carbon composite positive electrode materials and sulfurized polyacrylonitrile; and / or the negative electrode active material is selected from metallic lithium.

[0085] In some embodiments, the energy storage device of the present invention is a capacitor. When the energy storage device is a capacitor, the positive electrode active material is selected from one or more of metal oxides, conductive polymers, and carbon materials, preferably one or more of MnO2, NiO, Co3O4, polyaniline, polypyrrole, activated carbon, graphene, and biochar; and / or the negative electrode active material is selected from one or more of metals, carbon materials, conductive polymers, metal oxides, and metal-organic framework (MOF) derived materials, preferably one or more of aluminum, zinc, activated carbon, graphite, polyaniline, polypyrrole, polythiophene, and MnO2. The energy storage device is also described in a method for preparing a secondary battery, such as a lithium-ion secondary battery.

[0086] A second aspect of the present invention provides a method for preparing an energy storage device, such as a secondary battery like a lithium-ion secondary battery, according to the first aspect of the present invention, comprising:

[0087] (1) Provide a porous membrane and a non-aqueous liquid electrolyte or gel electrolyte, or provide a solid electrolyte;

[0088] (2) Provide a positive electrode slurry including a positive electrode active material and a negative electrode slurry including a negative electrode active material;

[0089] (3) Simultaneously or in any order, the positive electrode slurry is coated on one side of the separator or solid electrolyte, and the negative electrode slurry is coated on the side of the separator or solid electrolyte opposite to the positive electrode slurry, and then dried;

[0090] (4) Deposit a positive current collector on the obtained positive electrode active material layer, and deposit a negative current collector on the obtained negative electrode active material; and

[0091] (5) The product obtained in step (4) is contained in a battery package, wherein, if a separator is used, a non-aqueous liquid electrolyte or a gel electrolyte is injected into the product obtained in step (4).

[0092] Step (1)

[0093] As mentioned above, the present invention does not have any particular requirements on the type of diaphragm, non-aqueous liquid electrolyte or gel electrolyte or solid electrolyte, and any diaphragm, non-aqueous liquid electrolyte or gel electrolyte or solid electrolyte conventionally used in the art can be used.

[0094] Step (2)

[0095] The positive electrode slurry can be prepared using methods commonly used in the art. For example, the positive electrode slurry is prepared by uniformly dispersing the positive electrode active material, conductive agent, binder, etc., in a solvent (e.g., N-methylpyrrolidone (NMP)) to obtain the positive electrode slurry.

[0096] In some embodiments, the solid content of the positive electrode slurry is 80-90% (by mass).

[0097] Similarly, the negative electrode slurry can be prepared using methods commonly used in the art. For example, the negative electrode slurry is prepared by uniformly dispersing the negative electrode active material, conductive agent, binder, etc., in a solvent (e.g., N-methylpyrrolidone (NMP)) to obtain the negative electrode slurry.

[0098] In some embodiments, the solid content of the negative electrode slurry is 80-90%.

[0099] Step (3)

[0100] In step (3), the positive electrode slurry is coated onto one side of the separator or solid electrolyte simultaneously or in any order, and the negative electrode slurry is coated onto the side of the separator or solid electrolyte opposite to the positive electrode slurry, and then dried.

[0101] This invention does not impose any particular requirements on the coating method for the positive or negative electrode slurry; any coating method conventionally used in the art can be employed. Examples include blade coating, brush coating, spray coating, and dip coating. In some embodiments, the coating speed can be in the range of 1.0-15.0 cm / s, preferably 1.0-8.0 cm / s.

[0102] In some embodiments, after coating, drying can be performed at a temperature of 10-80°C and a vacuum of 0.01-10000 Pa to remove the solvent.

[0103] In some embodiments, the uniformly mixed positive or negative electrode slurry can be heated (e.g., to a temperature of 10-150°C) and then sprayed onto a separator or solid electrolyte. In this case, the slurry still has a high temperature after coating, and the solvent can be removed by evaporation after a period of time, resulting in a dry positive or negative electrode active material layer.

[0104] In the preparation method of this invention, the positive electrode slurry and the negative electrode slurry are coated on opposite sides of the separator or solid electrolyte. See also Figure 1 The positive electrode active material layer 101 is on one side of the separator 102, and the negative electrode active material layer 103 is on the other side of the separator 102; the positive electrode current collector 100 is deposited on the positive electrode active material layer 101, and the negative electrode current collector 104 is deposited on the negative electrode active material layer 103.

[0105] In some implementations, there is no requirement for the order of coating the positive electrode active material and coating the negative electrode active material; they can be performed simultaneously or sequentially.

[0106] Step (4)

[0107] In step (4), a positive current collector is deposited on the obtained positive active material layer, and a negative current collector is deposited on the obtained negative active material.

[0108] In some embodiments, the method for depositing the current collector includes one or more of magnetron sputtering, electrodeposition, electroless plating, spraying, and vapor deposition, with magnetron sputtering being preferred.

[0109] In some embodiments, the magnetron sputtering process conditions are: substrate temperature of 10-150°C, substrate rotation speed of 0-20 rpm, target-substrate distance of 20-200 mm; and main cavity vacuum of 5 × 10⁻⁶ mm. -3 -5×10 -6 The process gas pressure is 0.5-1.5 Pa, the power supply is 20-500 W, and the sputtering time is 60-3600 s.

[0110] In some embodiments, the preparation method according to the present invention further includes a rolling step of rolling the positive electrode active material layer or the negative electrode active material layer. As an example, the rolling may be performed after obtaining a dry positive electrode active material layer, or after obtaining a dry negative electrode active material layer, or after depositing a positive current collector, or after depositing a negative current collector, or at one or more of the above time points. Preferably, the rolling step is performed after obtaining dry positive and negative electrode active material layers on both sides of the separator, to facilitate the current collector deposition step and to allow for better physical and electrical contact between the deposited current collector and the active material layer.

[0111] In some embodiments, the rolling conditions are as follows: rolling pressure of 1-200 MPa, preferably 1-50 MPa; rolling temperature of 20-180°C; and rolling cycles of 1-10. For example, multiple rolling cycles at low pressure can be used. As an example, rolling can be performed 5 times at a pressure of 2-50 MPa. Multiple rolling cycles at low pressure are beneficial for improving the surface quality of the diaphragm, facilitating electrolyte wetting and lithium ion transport, thereby improving cycle performance. As an example, the pressure for rolling can be within the range of 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 150, 180, 200 MPa, or any two of these; the rolling temperature can be within the range of 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 °C, or any two of these; and / or the number of rolling cycles can be within the range of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or any two of these.

[0112] Step (5)

[0113] In step (5), the product obtained in step (4) is contained in a battery package, wherein, in the case of a separator, a non-aqueous liquid electrolyte or a gel electrolyte is injected into the product obtained in step (4).

[0114] This invention does not impose any particular requirements on the form of battery packaging. In some embodiments, the sodium-ion secondary battery may also include an outer packaging for encapsulating the electrode assembly and electrolyte. For example, the outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc., or it may be a soft pack, such as a pouch-type soft pack, for example, a soft pack made of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0115] There are no particular restrictions on the shape of sodium-ion secondary batteries; they can be cylindrical, square, or any other shape.

[0116] Energy storage devices such as secondary batteries, such as lithium-ion secondary battery production systems

[0117] A third aspect of the present invention provides a production system for an energy storage device, such as a secondary battery, including a lithium-ion secondary battery, comprising:

[0118] (a) A mixing device that mixes raw materials to obtain a positive electrode slurry or a negative electrode slurry;

[0119] (b) A coating apparatus that coats a positive or negative electrode slurry from a mixing device onto a separator or solid electrolyte;

[0120] (c) A drying apparatus for drying a slurry coated on the diaphragm or the solid electrolyte to obtain a positive electrode active material layer and / or a negative electrode active material layer;

[0121] (d) A rolling device for rolling a positive electrode active material layer or a negative electrode active material layer; and

[0122] (e) A current collector deposition device that deposits a positive current collector or a negative current collector on the diaphragm or solid electrolyte.

[0123] See Figure 9 1 and 3 are coating devices, which can coat positive and negative electrode slurries on both sides of the separator respectively; 2 and 4 are drying devices, which evaporate the solvent of the slurry by providing a certain temperature and vacuum to obtain the active material layer; 5 is a rolling device, which can achieve densification of the internal particles of the active material layer and improve the surface smoothness by rolling multiple times under low pressure without damaging the microstructure of the separator or solid electrolyte; 6 and 7 are magnetron sputtering devices, which can obtain the positive electrode current collector and the negative electrode current collector by magnetron sputtering of the positive electrode active material layer and the negative electrode active material layer respectively. Figure 9 The energy storage device manufacturing system shown can continuously process the diaphragm shown in a to obtain the integrated energy storage device shown in b. The energy storage device manufacturing system of the present invention has a simple process flow, and the equipment used is compatible with existing industrial production equipment. It is suitable for roll-to-roll production and can realize low-cost, continuous, and large-scale preparation of integrated energy storage devices with high production efficiency.

[0124] In a typical implementation, the separator a first passes through a coating device 1 to coat one side of the separator with a positive electrode slurry (or a negative electrode slurry). The separator coated with the positive electrode slurry (or negative electrode slurry) continues through a drying device 2 to dry the coated positive electrode slurry (or negative electrode slurry). Then, as the system continues forward, it passes through a coating device 3 to coat the opposite side of the separator to the side coated with the positive electrode slurry (or negative electrode slurry). Similarly, the separator coated with the negative electrode slurry (or positive electrode slurry) may continue through a drying device 4 to dry the coated negative electrode slurry (or positive electrode slurry). Optionally, the system further passes through a rolling device 5, preferably multiple rolling at low pressure, to achieve particle densification within the active material layer and improve surface smoothness. After rolling, the system further passes through a magnetron sputtering device 6 to deposit a positive electrode current collector (or negative electrode current collector) onto the positive electrode active material layer (or negative electrode active material layer). Similarly, the system further passes through a magnetron sputtering device 7 to deposit a negative current collector (or a positive current collector) on the negative electrode active material layer (or positive electrode active material layer). It will be readily understood by those skilled in the art that the above embodiments are merely illustrative, and that those skilled in the art can also make appropriate adjustments to the energy storage device production system of the present invention according to actual needs.

[0125] In some embodiments, the production system of the present invention is a continuous production system.

[0126] In some embodiments, the production system of the present invention is an automated production system. Those skilled in the art will readily understand that automated sample feeding devices for diaphragms, positive electrode slurries, negative electrode slurries, target materials, etc., can be used as needed to achieve automated production.

[0127] In some embodiments, at least one of the steps of coating, drying, rolling, or current collector deposition on one side of the diaphragm or solid electrolyte is performed independently of at least one of the above steps on the opposite side; preferably, coating, drying, rolling, and / or current collector deposition is performed first on one side of the diaphragm or solid electrolyte, and then coating, drying, rolling, and / or current collector deposition is performed on the opposite side of the diaphragm or solid electrolyte. Example

[0128] To make the objectives, technical solutions, and advantages of this invention clearer, the following description uses a lithium-ion secondary battery as an example to further illustrate the invention. Those skilled in the art will understand that, with appropriate adjustments to the embodiments of the lithium-ion secondary battery, the sodium-ion secondary battery, lithium-sulfur secondary battery, and capacitor of this invention can be obtained. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit its scope.

[0129] Example 1

[0130] Preparation of lithium-ion secondary batteries

[0131] Step (1)

[0132] diaphragm or solid electrolyte

[0133] The diaphragm is model Celgard2500, composed of polypropylene / polyethylene / polypropylene composite diaphragm, and manufactured by Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0134] Step (2)

[0135] Positive electrode slurry:

[0136] The positive electrode slurry is prepared by dispersing the positive electrode active material, conductive agent, and binder in an N-methylpyrrolidone (NMP) solvent. The positive electrode active material is lithium iron phosphate, model P198-S20, accounting for 80% of the total mass of the positive electrode slurry excluding the solvent; the conductive agent is Super-P conductive carbon black, accounting for 10% of the total mass of the positive electrode slurry excluding the solvent; and the binder is polyvinylidene fluoride (PVDF), accounting for 10% of the total mass of the positive electrode slurry excluding the solvent. All materials were purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0137] Negative electrode slurry:

[0138] The negative electrode slurry is prepared by dispersing the negative electrode active material, conductive agent, and binder in N-methylpyrrolidone (NMP) solvent. The negative electrode active material is artificial fast-charging graphite, specifically fast-charging graphite-B, and comprises 80% of the negative electrode slurry by weight (excluding the solvent). The conductive agent is Super-P conductive carbon black, comprising 10% of the negative electrode slurry by weight (excluding the solvent). The binder is polyvinylidene fluoride (PVDF), comprising 10% of the negative electrode slurry by weight (excluding the solvent). All materials were purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0139] Step (3)

[0140] The positive and negative electrode slurries were coated onto the separator or solid electrolyte and then dried. The coating and drying conditions were as follows: coating was done by blade coating at a speed of 3 cm / s; the drying temperature was 30℃, the vacuum degree during drying was 0.1 Pa, and the drying time for both the positive and negative electrode slurries after coating was 36 h. The positive electrode active material loading was 1.0 mAh / cm³. 2 The loading capacity of the negative electrode active material is 1.15 mAh / cm³. 2That is, the negative electrode / positive electrode capacity ratio (N / P ratio) is 1.15 (when the loading of positive or negative electrode active materials changes, the loading of negative or positive electrode active materials is adjusted accordingly to maintain the N / P ratio at 1.15). After coating is completed, rolling is performed under the following conditions: pressure 20MPa, temperature 30℃, and rolling 5 times.

[0141] Step (4)

[0142] Magnetron sputtering of positive and negative electrode current collectors. Using the positive and negative electrode active material layers prepared in step (3) as substrates, current collectors were obtained by magnetron sputtering with aluminum (positive electrode) and copper (negative electrode) metal targets, respectively. The magnetron sputtering conditions were as follows: substrate temperature (i.e., temperature of the positive and negative electrode active material layers) was 20℃, substrate rotation speed was 5 r / min, target-substrate distance was 300 mm, and main cavity vacuum was 5 × 10⁻⁶. -4 Argon was used as the process gas at a pressure of 0.6 Pa, and the sputtering power was 100 W. The sputtering times were 20 min (positive electrode active material layer) and 15 min (negative electrode active material layer), respectively, resulting in positive and negative electrode current collector layer thicknesses of 2 μm. This yielded an integrated battery cell.

[0143] Step (5)

[0144] electrolyte

[0145] The electrolyte used was a lithium salt electrolyte, consisting of 1 mol / L LiPF6 dissolved in a solvent with a volume ratio of DMC:EC:DEC = 1:1:1, purchased from Suzhou Duoduo Chemical Reagent Co., Ltd.

[0146] Secondary batteries

[0147] A coin cell battery is obtained by placing a positive electrode pad, the integrated battery cell, and a negative electrode spring sheet from bottom to top inside the positive electrode shell, injecting electrolyte, and then snapping the negative electrode shell together and pressing it into place. The positive electrode shell, negative electrode shell, pad, and spring sheet used are all made of stainless steel and were purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0148] Example 2

[0149] Step 1: Coat one side of the diaphragm with negative electrode slurry, dry it, and then magnetron sputter the negative electrode current collector. The composition of the negative electrode slurry, the loading of the negative electrode active material, and the process parameters for coating, drying, rolling, and magnetron sputtering are the same as in Example 1.

[0150] Step 2: Coat the positive electrode slurry onto the aluminum foil, dry it, and roll it to obtain the positive electrode sheet. The composition of the positive electrode slurry, the loading of the positive electrode active material, and the process parameters for coating and drying are the same as in Example 1.

[0151] Step 3: Place the positive electrode pad, positive electrode sheet, negative electrode-separator composite membrane obtained in Step 1, and negative electrode spring sheet in the positive electrode shell from bottom to top. Inject electrolyte, snap the negative electrode shell in place, and press the sheet to obtain a coin cell. The positive electrode shell, negative electrode shell, pad, spring sheet, and electrolyte used are the same as in Example 1.

[0152] Example 3

[0153] Step 1: Coating the positive electrode slurry and negative electrode slurry on both sides of the separator, drying, and rolling. The composition of the positive electrode slurry and negative electrode slurry, the loading of positive active material, the loading of negative active material, and the process parameters for coating, drying, and rolling are the same as in Example 1.

[0154] Step 2: Carbon-coated copper foil is bonded to the negative electrode active material layer via hot pressing, and carbon-coated aluminum foil is bonded to the positive electrode active material layer via hot pressing to obtain the battery cell. In the hot pressing step, the pressure is 30-50 MPa and the temperature is 100℃. Both the carbon-coated copper foil and the carbon-coated aluminum foil were purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0155] Step 3: Assemble the obtained battery cells into button cells. The battery casing material, electrolyte composition, and assembly process are the same as in Example 1.

[0156] Examples 4-6

[0157] Except that the loading capacity of the positive electrode active material is changed to 2.0 mAh / cm³. 2 Except for the above, the other conditions in Examples 4, 5 and 6 are the same as those in Examples 1, 2 and 3, respectively.

[0158] Examples 7-9

[0159] Except that the loading capacity of the positive electrode active material is changed to 3.0 mAh / cm³. 2 Except for the above, the other conditions in Examples 7, 8 and 9 are the same as those in Examples 1, 2 and 3, respectively.

[0160] Examples 10-12

[0161] Except for changing the positive electrode active material to NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 Except for O2), the other conditions in Examples 10, 11 and 12 are the same as those in Examples 7, 8 and 9, respectively.

[0162] The NCM811 is a nickel-cobalt-manganese NCM811 (single crystal), purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0163] Examples 13-15

[0164] Except for changing the negative electrode active material to Si / C, the other conditions in Examples 13, 14 and 15 are the same as those in Examples 7, 8 and 9, respectively.

[0165] The Si / C material is a 650-K silicon-carbon anode material, purchased from Dongguan Kelude Experimental Equipment Technology Co., Ltd.

[0166] Examples 16-18

[0167] Except for changing the positive electrode active material to NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 Apart from O2), the other conditions in Examples 16, 17 and 18 are the same as those in Examples 13, 14 and 15, respectively.

[0168] II. Evaluation of Implementation Examples

[0169] 1. Specific capacity test

[0170] After assembly, the button cells were left to stand at 50°C for 12 hours to allow the electrolyte to wet the active material layer. The testing process involved first performing 10 charge-discharge cycles at 0.1C to activate the electrode materials, followed by cycle tests at various set rates. For each cycle, the discharge cutoff voltage for graphite-LFP cells was 2.5V, and the charge cutoff voltage was 3.7V; for graphite-NCM811 cells, the discharge cutoff voltage was 2.7V, and the charge cutoff voltage was 4.3V; for Si / C-LFP cells, the discharge cutoff voltage was 2.5V, and the charge cutoff voltage was 3.7V; and for Si / C-NCM811 cells, the discharge cutoff voltage was 2.7V, and the charge cutoff voltage was 4.3V. After each charge or discharge cycle, the cells were left to stand for 5 minutes before proceeding to the next step.

[0171] The number of cycles is 100-300 (excluding the initial 10 cycles for activation). The average discharge capacity of the total cycle is obtained by averaging the discharge capacity of each cycle. The average discharge capacity is used as the numerator, and the weight (dry weight) of the positive electrode active material layer in the battery is used as the denominator (excluding the weight of current collectors, separators, and other inactive components, thus only reflecting the specific capacity of the positive electrode active material). The average discharge specific capacity is obtained by dividing the two.

[0172] 2. Cycle retention rate test

[0173] After the cycle test is completed, the discharge specific capacity of the last cycle is divided by the discharge specific capacity of the first cycle after the activation process is completed to obtain the capacity retention rate after a certain number of cycles.

[0174] The performance test results of Examples 1-18 can be found here. Figures 2 to 8 The specific capacity and capacity retention rate after n cycles are summarized in Table 1.

[0175] Table 1. Partial process conditions and electrochemical performance test results of Examples 1-18

[0176] *: Number of cycles;

[0177] **: Examples 7'-9' use a different charging rate than Examples 7-9.

[0178] Referring to Examples 1-3, the secondary battery of Example 1 has an average specific capacity of 149.7 mAh / g after 100 cycles, which is higher than that of Example 2 (140.7 mAh / g) or Example 3 (139.5 mAh / g). Meanwhile, the cycle retention rate of Example 1 is 97.6%, which is higher than that of Example 2 (95.5%) or Example 3 (90.7%). Therefore, compared to conventional batteries that coat positive and negative electrode active materials onto the current collectors, and batteries that coat active materials only on one side of the separator and deposit current collectors while attaching the other side of the separator to the current collector coated with active materials, the battery of the present invention can achieve higher specific capacity and higher cycle capacity retention.

[0179] Referring to Examples 7-9, the loading of the active material is 3 mAh / cm³. 2 In the case of the prior art, the secondary battery of Example 7 exhibits an average specific capacity of 139.4 mAh / g after 100 cycles, significantly higher than that of Example 8 (124.4 mAh / g) or Example 9 (96.4 mAh / g). Simultaneously, the cycle retention rate of Example 7 is 93.9%, significantly higher than that of Example 8 (81.7%) or Example 9 (70.0%). In other words, with a higher active material loading, the improvement in specific capacity and cycle performance of the secondary battery of the present invention is more pronounced. Those skilled in the art will readily understand that, compared to the prior art, the secondary battery of the present invention is advantageous in achieving improved specific capacity and cycle performance when increasing the content of active material to improve the capacity of the secondary battery. Furthermore, this also contributes to the "thinning" and "lighter" design of the secondary battery.

[0180] Referring to Examples 7'-9', at a charge / discharge rate of 1.0C, the secondary battery of Example 7' exhibits an average specific capacity of 133.1 mAh / g after 300 cycles, significantly higher than that of Example 8' (85.9 mAh / g) or Example 9' (58.3 mAh / g). Simultaneously, the cycle retention rate of Example 7' is 91.3%, significantly higher than that of Example 8' (32.3%) or Example 9' (4.0%). In other words, at higher charge / discharge rates, the improvement in specific capacity and cycle performance of the secondary battery of the present invention is more pronounced. This indicates that the secondary battery of the present invention also possesses improved rate performance.

[0181] Referring to Examples 13-15, after 150 cycles, the secondary battery of Example 13 exhibits an average specific capacity of 137.6 mAh / g, significantly higher than that of Example 14 (114.6 mAh / g) or Example 15 (114.7 mAh / g). Simultaneously, the cycle retention rate of Example 13 is 91.9%, significantly higher than that of Example 14 (65.3%) or Example 15 (60.0%). In other words, the improvement in specific capacity and cycle performance of the secondary battery of the present invention is more pronounced with a greater number of cycles.

[0182] The above description is merely an exemplary embodiment of the present invention. It should be noted that those skilled in the art can make improvements to the present invention without departing from the inventive concept, and all such improvements fall within the scope of protection of the present invention.

Claims

1. Energy storage devices, including Porous membranes impregnated with non-aqueous liquid electrolytes or gel electrolytes, or solid electrolytes; A positive electrode active material layer is coated on one side of the separator or solid electrolyte; A negative electrode active material layer is coated on the side of the separator or solid electrolyte opposite to the positive electrode active material layer; A positive electrode current collector, which is deposited on the positive electrode active material layer; and The negative electrode current collector is deposited on the negative electrode active material layer; After obtaining dry positive and negative electrode active material layers on both sides of the separator or solid electrolyte, and before the current collector deposition step, a rolling step is performed. The rolling conditions are as follows: Roller pressure is 1-50 MPa; The rolling temperature is 20-180℃; and The number of rolling cycles is 2-10. The energy storage device is a lithium-ion secondary battery, and the loading of the positive electrode active material is 3.0-5.0 mAh / cm³. 2 .

2. The energy storage device according to claim 1, satisfying one or more of the following conditions: i. The diaphragm is selected from one or more of polyethylene, polypropylene, polyethylene terephthalate, polyimide, polyamide, and poly(p-phenylene terephthalamide); ii. The non-aqueous liquid electrolyte includes a non-aqueous organic solvent, wherein the non-aqueous organic solvent is selected from one or more of the following: ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. iii. The gel electrolyte is selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride hexafluoropropylene copolymer, polyethylene oxide, polyacrylonitrile, and polymethyl methacrylate; iv. The solid electrolyte is selected from one or more of inorganic solid electrolytes or polymer solid electrolytes; v. The positive electrode active material layer and / or the negative electrode active material layer comprises one or more of graphite, superconducting carbon, carbon black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers; and / or vi. The positive electrode active material layer and / or the negative electrode active material layer further include one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, styrene-butadiene rubber, waterborne acrylic resin, and sodium carboxymethyl cellulose.

3. The energy storage device according to claim 1, wherein the loading of the positive electrode active material is 4.0-5.0 mAh / cm³. 2 ; and / or The loading of the negative electrode active material is 0.5-5.0 mAh / cm³. 2 .

4. The energy storage device according to any one of claims 1-3, wherein the thickness of the positive electrode current collector is 0.5-5 μm, and / or The thickness of the negative electrode current collector is 0.5-5 μm.

5. The energy storage device according to any one of claims 1-3, wherein the diaphragm or solid electrolyte further comprises a surface coating, the surface coating comprising one or more of alumina, hydrated alumina, attapulgite, aramid, carbon nanotubes, graphene, polyvinylidene fluoride, styrene-butadiene rubber, waterborne acrylic resin, and sodium carboxymethyl cellulose.

6. The energy storage device according to any one of claims 1-3, wherein the positive electrode active material is selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphates with an olivine structure, and / or The negative electrode active material is selected from one or more of the following: natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon-based materials, tin-based materials, lithium titanate, and metallic lithium.

7. The energy storage device according to any one of claims 1-3, wherein the non-aqueous liquid electrolyte comprises a lithium salt, the lithium salt being selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorophosphate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

8. The energy storage device according to claim 2, wherein the solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes and polymer solid electrolytes.

9. The energy storage device according to claim 3, wherein the loading of the negative electrode active material is 1.0-3.0 mAh / cm³. 2 .

10. The energy storage device according to claim 6, wherein the positive electrode active material is selected from LiMn2O4, LiNiMnCoO2, and LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 One or more of O2 and LiFePO4.

11. The energy storage device according to claim 6, wherein the negative electrode active material is selected from one or more of graphite and silicon-based materials.

12. The energy storage device according to claim 6, wherein the negative electrode active material is selected from one or more of graphite, silicon-carbon composite and silicon alloy.

13. The energy storage device according to claim 2, wherein the carbon black is selected from acetylene black and Ketjen black.

14. A method for preparing an energy storage device according to any one of claims 1-13, comprising: (1) Provide a porous membrane and a non-aqueous liquid electrolyte or gel electrolyte, or provide a solid electrolyte; (2) Provide a positive electrode slurry including a positive electrode active material and a negative electrode slurry including a negative electrode active material; (3) Simultaneously or in any order, the positive electrode slurry is coated on one side of the separator or solid electrolyte, and the negative electrode slurry is coated on the side of the separator or solid electrolyte opposite to the positive electrode slurry, and then dried; (4) Deposit a positive current collector on the obtained positive electrode active material layer, and deposit a negative current collector on the obtained negative electrode active material; and (5) The product obtained in step (4) is contained in a battery package, wherein, if a separator is used, a non-aqueous liquid electrolyte or a gel electrolyte is injected into the product obtained in step (4). After obtaining dry positive and negative electrode active material layers on both sides of the separator or solid electrolyte, and before the current collector deposition step, a rolling step is performed. The rolling conditions are as follows: Roller pressure is 1-50 MPa; The rolling temperature is 20-180℃; and The number of rolling cycles is 2-10.

15. The preparation method according to claim 14, wherein the deposition includes one or more of magnetron sputtering, electrodeposition, electroless plating, spraying, and vapor deposition.

16. The preparation method according to claim 15, wherein the deposition is magnetron sputtering.

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