Membrane electrode and solid-state lithium battery and preparation method thereof

Abstract

The present invention relates to the technical field of lithium-ion batteries, and discloses a membrane electrode, a solid-state lithium battery and a preparation method thereof. The membrane electrode sequentially includes a current collector, at least one positive electrode layer and at least one electrolyte layer; the porosity of the membrane electrode is 1% - 15%, the compaction density is 2.5 g / cm<supgt;3< / supgt> - 4.8 g / cm<supgt;3< / supgt>, and the peel strength between the positive electrode layer and the electrolyte layer is 600 - 800 N / m. This membrane electrode has a low porosity and a high compaction density, and the electrodes and the electrolyte in the membrane electrode are in close contact, which can significantly reduce the impedance of the solid-state lithium battery prepared from this membrane electrode and improve the battery energy density and cycle rate performance.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries and discloses a membrane electrode and a solid-state lithium battery and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in consumer electronics and electric vehicles. In order to improve the safety and energy density of lithium-ion batteries, it is necessary to use solid electrolytes to replace flammable electrolytes and research and develop high-performance solid-state lithium batteries.

[0003] At present, the compaction density of the positive and negative electrodes in the preparation process of lithium-ion batteries is relatively low. This is because in the process of preparing the pole piece, the active material, conductive agent, and binder must first be mixed in a liquid solvent to form a slurry, which is then coated on the current collector and then dried to remove the solvent. In the above process, there may be a reaction between the solvent and the active material, which reduces the specific capacity and stability of the active material; after the solvent is removed from the pole piece, a certain amount of pores are formed, resulting in a low energy density of the lithium battery. In addition, the performance of some solvent-sensitive materials is reduced or even fails after contact with solvents, such as the slurry of high-nickel ternary materials absorbing moisture and becoming jelly, and the sulfide electrolyte material is deactivated after contact with common solvents. In addition, the existing manufacturing methods will reduce the performance of solid-state lithium batteries. For example, there are pores of different sizes in the electrodes prepared by the wet method, which makes it impossible for the active material in the electrode to completely contact with the solid electrolyte, increasing the impedance between the electrode and the solid electrolyte, and affecting the battery rate performance.

[0004] According to the production process, lithium batteries can be divided into wound batteries and laminated batteries. During the charging and discharging process of laminated batteries, the stress is evenly distributed inside the electrode, so the distribution of current in the laminated battery is also more even, which is conducive to improving the rate performance of the battery, reducing polarization, and improving the energy density of the battery. Moreover, its shape and structure are flexible, which can make full use of the space of the shell corners, improve the energy density of the battery, and can also be used to produce specialized products with complex shapes, which is more suitable for the preparation of solid-state batteries. However, laminated batteries have the disadvantages of low pole piece cutting pass rate, it is difficult to maintain high consistency of pole piece quality (section, burrs, etc.), low lamination efficiency and pole piece alignment accuracy, and high process complexity. Generally, the generation of pole piece burrs and dust can be reduced from three aspects: punching method, punching die structure, and punching die material and processing accuracy. At present, the commonly used measures include optimizing the mold structure; improving the mold manufacturing and assembly accuracy; using laser die cutting method; using die cutting and lamination integrated machine to avoid collision and friction between pole pieces and material boxes, and reduce the potential risk of pole piece defects. However, these improvement measures have limited effects and will undoubtedly increase manufacturing costs. Therefore, it is necessary to design and manufacture high-performance solid-state lithium batteries from both the battery structure and production process. Summary of the invention

[0005] The object of the present invention is to overcome the problems existing in the prior art, namely, the wet-prepared electrodes have pores of different sizes, which cannot achieve good microscopic and macroscopic contact with the solid electrolyte, and there may be side reactions between the solvent and the electrolyte or electrode components, and the solid-state battery process is complex. Provided are a membrane electrode, a solid-state lithium battery and a preparation method thereof. The membrane electrode has a low porosity and a high tap density, and the electrode and the electrolyte in the membrane electrode are in close contact, which can significantly reduce the impedance of the solid-state lithium battery prepared from the membrane electrode, and improve the battery energy density and cycle rate performance.

[0006] To achieve the above object, in the first aspect of the present invention, there is provided a membrane electrode, characterized in that the membrane electrode sequentially includes a current collector, at least one positive electrode layer and at least one electrolyte layer;

[0007] The porosity of the membrane electrode is 1%-15%, and the tap density is 2.5 g / cm 3 -4.8 g / cm 3 , and the peel strength between the positive electrode layer and the electrolyte layer is 600-800 N / m.

[0008] In the second aspect of the present invention, there is provided a preparation method of a membrane electrode, characterized in that the method includes the following steps:

[0009] (1) Mix, knead and first hot-press the positive electrode components to prepare a film, and perform the first lamination with the current collector to obtain a positive electrode plate;

[0010] (2) Mix, knead and second hot-press the electrolyte components to prepare a film, and perform the second lamination with the positive electrode plate obtained in step (1) to obtain the membrane electrode.

[0011] In the third aspect of the present invention, there is provided a membrane electrode prepared by the above preparation method.

[0012] In the fourth aspect of the present invention, there is provided a solid-state lithium battery, the solid-state lithium battery includes a lithium negative electrode and a membrane electrode, characterized in that the membrane electrode is the above membrane electrode.

[0013] In the fifth aspect of the present invention, there is provided a method for preparing the above solid-state lithium battery, characterized in that the method includes the following steps:

[0014] S1. In an argon atmosphere with a water content ≤ 10 ppm and an oxygen content ≤ 10 ppm, laminate and cut the lithium negative electrode and the membrane electrode to obtain a battery cell;

[0015] S2. Stack at least two battery cells, weld the tabs, and encapsulate the housing to obtain the solid-state lithium battery.

[0016] Through the above technical solutions, the membrane electrode, the solid-state lithium battery and the preparation method thereof provided by the present invention achieve the following beneficial effects:

[0017] The membrane electrode provided by the present invention has a low porosity and a high tap density, improving the microscopic contact between the electrode and the electrolyte and reducing the battery impedance, thereby further improving the energy density and cycle rate performance of the solid-state lithium battery prepared from the membrane electrode.

[0018] Furthermore, in the preparation method of the membrane electrode provided by the present invention, no solvent is used, which can avoid the performance degradation or failure of solvent-sensitive materials after contacting the solvent, and reduce the adverse effects of the residual solvent after drying. In particular, the electrode and the solid electrolyte membrane in the membrane electrode are integrally formed, with close contact between the two, which can reduce the battery impedance. Moreover, without the influence of solvent small molecules in the electrolyte, the breakdown voltage resistance of the electrolyte can be improved, further improving the rate performance and cycle life of the battery.

[0019] Even further, for the solid-state lithium battery provided by the present invention, a step-by-step cutting process is adopted, and the cutting method is changed from up-and-down reciprocating punching to rolling slicing, which can extend the service life of the mold, reduce the generation of dust, and keep the battery manufacturing environment clean; at the same time, burrs can be reduced, improving the safety of the battery. Description of the Drawings

[0020] Figure 1 is a schematic diagram of the cutting process of the solid-state lithium battery of the present invention.

[0021] Figure 2 is the cycle curve of the solid-state lithium batteries prepared in Example 1 and Comparative Example 1. Detailed Embodiments

[0022] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0023] The first aspect of the present invention provides a membrane electrode, characterized in that the membrane electrode sequentially includes a current collector, at least one positive electrode layer and at least one electrolyte layer;

[0024] The porosity of the membrane electrode is 1% - 15%, and the tap density is 2.5 g / cm 3 - 4.8 g / cm 3 , and the peel strength between the positive electrode layer and the electrolyte layer is 600 - 800 N / m.

[0025] In the present invention, the membrane electrode has a low porosity and a high compaction density, which improves the microscopic contact between the electrode and the electrolyte and reduces the battery impedance, thereby further improving the energy density and cycle rate performance of the solid-state lithium battery prepared from the membrane electrode.

[0026] Furthermore, when the porosity of the membrane electrode is 5%-10%, the membrane electrode and the solid-state lithium battery prepared from the membrane electrode have more excellent performance.

[0027] Furthermore, when the positive electrode layer is a lithium cobalt oxide positive electrode material, the compaction density of the membrane electrode is 4.5 g / cm 3 -4.8 g / cm 3 ; or, when the positive electrode layer is a lithium manganese oxide positive electrode material, the compaction density of the membrane electrode is 3.5 g / cm 3 -3.9 g / cm 3 ; or, when the positive electrode layer is a multi-component positive electrode material, the compaction density of the membrane electrode is 3.9 g / cm 3 -4.5 g / cm 3 ; or, when the positive electrode layer is an olivine positive electrode material, the compaction density of the membrane electrode is 2.5 g / cm 3 -3.2 g / cm 3 ; or, when the positive electrode layer is a lithium-rich manganese-based positive electrode material, the compaction density of the membrane electrode is 2.6 g / cm 3 -3 g / cm 3 When this is the case, the membrane electrode and the solid-state lithium battery prepared from the membrane electrode have more excellent performance.

[0028] In the present invention, the multi-component positive electrode material is selected from at least one of lithium nickel manganese oxide positive electrode material, lithium nickel cobalt manganese oxide positive electrode material, lithium nickel cobalt aluminum oxide positive electrode material, etc. The olivine positive electrode material is selected from at least one of lithium iron phosphate positive electrode material, lithium manganese iron phosphate positive electrode material, lithium manganese phosphate positive electrode material, etc.

[0029] Furthermore, when the peel strength between the positive electrode layer and the electrolyte layer is 650-750 N / m, the membrane electrode and the solid-state lithium battery prepared from the membrane electrode have more excellent performance.

[0030] In the present invention, the membrane electrode may include a plurality of positive electrode layers and / or a plurality of electrolyte layers, and each positive electrode layer and / or electrolyte layer may have different components to meet the requirements of different functional batteries.

[0031] In the present invention, preferably, the membrane electrode includes 1 positive electrode layer and 2 electrolyte layers.

[0032] In the second aspect of the present invention, a method for preparing a membrane electrode is provided, characterized in that the preparation method includes the following steps:

[0033] (1) Mix, knead, and perform the first hot pressing on the positive electrode components to prepare a film, and then perform the first lamination with the current collector to obtain the positive electrode plate.

[0034] (2) Mix, knead, and perform the second hot pressing on the electrolyte components to prepare a film, and then perform the second lamination with the positive electrode plate obtained in step (1) to obtain the membrane electrode.

[0035] In the present invention, in the method for preparing the membrane electrode, no solvent is used, which can avoid the performance reduction or failure of solvent-sensitive materials after contacting the solvent, and reduce the adverse effects of the residual solvent after drying.

[0036] Furthermore, the integration of the electrode and the solid electrolyte membrane in the membrane electrode has the advantage of close contact, which can reduce the battery impedance. Moreover, without the influence of solvent small molecules in the electrolyte, the voltage resistance of the electrolyte can be improved, further improving the rate performance and cycle life of the battery.

[0037] According to the present invention, in step (1), the positive electrode components include a positive electrode active material, a conductive agent, a lithium salt, and a binder.

[0038] According to the present invention, the mass ratio of the positive electrode active material, the conductive agent, the lithium salt, and the binder is 65-98:0.5-10:0.5-10:1-15.

[0039] Furthermore, the mass ratio of the positive electrode active material, the conductive agent, the lithium salt, and the binder is 70-92:1-5:1-5:2-10.

[0040] According to the present invention, the positive electrode active material is selected from lithium cobaltate (LiCoO2), lithium manganate (LiMnO2), lithium nickel manganese oxide (LiNi 1-α Mn α O2, 0 < α < 1), lithium nickel cobalt manganese oxide (LiNi β Co γ Mn δ O2, β + γ + δ = 1, β, γ, and δ are all greater than 0), lithium nickel cobalt aluminate (LiNi κ Co λ Al μ O2, κ + λ + μ = 1, κ, λ, and μ are all greater than 0), etc. multi-component positive electrode materials, olivine positive electrode materials such as lithium iron phosphate (LiFePO4), lithium iron manganese phosphate (LiFeMnPO4), lithium manganese phosphate (LiMnPO4), and lithium-rich manganese-based materials [σLi2MnO3·(1-σ)LiNi ω Co γ Mn δAt least one of O2, where 0 < σ < 1, ω + γ + δ = 1, and ω, γ, and δ are all greater than 0.

[0041] According to the present invention, the conductive agent is selected from at least one of Super P, acetylene black, graphite, KS-6, carbon nanotubes, graphene, and carbon fiber.

[0042] According to the present invention, the lithium salt is selected from at least one of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), and lithium difluoro(oxalato)borate (LiDFOB).

[0043] According to the present invention, the binder is selected from small molecule organic compounds and / or high molecular polymers, and the mass ratio of the small molecule organic compound to the high molecular polymer is 0:100 - 100:0, preferably 20 - 80:80 - 20.

[0044] In the present invention, the small molecule organic compound is selected from acrylate compounds and / or vinyl ester compounds, preferably at least one of polyethylene glycol dimethyl ether (PEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol diacrylate (PEGDA), polyethylene glycol dimethacrylate (PEGDMA), triethylene glycol dimethacrylate (TEGDMA), and trimethylolpropane triacrylate (TMPTA).

[0045] Furthermore, when a small molecule organic compound is selected as the binder, the binder further includes an initiator, and based on the amount of the binder, the amount of the initiator is 0.1 - 5 wt%, preferably 0.5 - 2 wt%.

[0046] In the present invention, the initiator is selected from azo initiators and / or peroxide initiators, preferably at least one of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, and methyl ethyl ketone peroxide.

[0047] In the present invention, the high molecular polymer is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), (vinylidene fluoride - hexafluoropropylene) copolymer (PVDF - HFP), polyethylene oxide (PEO), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), polypropylene carbonate (PPC), polycarbonate ethylene carbonate (PEC), and polycaprolactone (PCL).

[0048] According to the present invention, the current collector is aluminum foil, preferably reticulated aluminum foil and / or carbon-coated aluminum foil.

[0049] According to the present invention, in step (2), the electrolyte components include an organic substance, a lithium salt, and an inorganic nano-powder.

[0050] According to the present invention, based on the total weight of the electrolyte components, the dosage of the organic substance is 5-90 wt%, the dosage of the lithium salt is 5-50 wt%, and the content of the inorganic nano-powder is 0-90 wt%.

[0051] Furthermore, based on the total weight of the electrolyte components, the dosage of the organic substance is 10-80 wt%, the dosage of the lithium salt is 10-36 wt%, and the dosage of the inorganic nano-powder is 10-70 wt%.

[0052] According to the present invention, the organic substance is selected from small molecule organic substances and / or high molecular polymers.

[0053] According to the present invention, the mass ratio of the small molecule organic substance to the high molecular polymer is 0:100-100:0, preferably 20-80:80-20.

[0054] According to the present invention, the small molecule organic substance is selected from acrylate compounds and / or ether compounds.

[0055] In the present invention, the small molecule organic substance is selected from at least one of polyethylene glycol dimethyl ether (PEGDME), triethylene glycol dimethyl ether (TEGDME), polyethylene glycol diacrylate (PEG200DA, PEG400DA, PEG600DA), polyethylene glycol dimethacrylate (PEG200DMA, PEG400DMA, PEG600DMA), triethylene glycol dimethacrylate (TEGDMA), and trimethylolpropane triacrylate (TMPTA).

[0056] Furthermore, when a small molecule organic substance is selected as the organic substance, the organic substance further includes an initiator. Based on the dosage of the organic substance, the dosage of the initiator is 0.1-5 wt%, preferably 0.5-2 wt%.

[0057] In the present invention, the initiator is selected from azo initiators and / or peroxide initiators, preferably selected from at least one of azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide, tert-butyl benzoyl peroxide, and methyl ethyl ketone peroxide.

[0058] In the present invention, the high molecular polymer includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), (vinylidene fluoride - hexafluoropropylene) copolymer (PVDF - HFP), polyethylene oxide (PEO), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN), poly(propylene carbonate) (PPC), poly(ethylene carbonate) (PEC), and polycaprolactone (PCL).

[0059] According to the present invention, the lithium salt is at least one of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), and lithium difluoro(oxalato)borate (LiDFOB).

[0060] According to the present invention, the inorganic nano - powder is selected from at least one of silicon dioxide (SiO2), titanium dioxide (TiO2), aluminum oxide (Al2O3), zirconium dioxide (ZrO2), lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 (PO4)3), lithium aluminum lanthanum zirconate (Li 6.24 Al 0.24 La3Zr2O 11.98 ), lithium lanthanum niobium zirconate (Li 6.4 La3Zr 1.4 Nb 0.6 O 12 ), lithium lanthanum titanate (Li 0.5 La 0.5 TiO3), Li 10 GeP2S 12 , Li2S - P2S5, Li3InCl3Br3, Li3InCl6, Li3InBr6, Li2InCa 0.5 Br6, and Li 2.8 Y 0.8 Zr 0.2 Cl 5.4 Br 0.4 .

[0061] In the present invention, adding the above - mentioned specific inorganic nano - powder to the electrolyte components can improve the properties of the solid - state electrolyte such as ionic conductivity and interfacial stability, making the prepared membrane electrode and solid - state lithium battery have more excellent properties.

[0062] According to the present invention, the conditions for the first hot pressing include: a line load of 200 - 600 N / mm, a temperature of 60 - 100 °C, and a roller speed of 2 m / min - 16 m / min; the conditions for the first laminating include: a line load of 200 - 300 N / mm, a temperature of 80 - 100 °C, and a roller speed of 2 m / min - 16 m / min.

[0063] In the present invention, under the above first hot pressing conditions, the positive electrode component is prepared into a film, and under the first laminating conditions, the positive electrode component film is laminated with the current collector to obtain a positive electrode sheet. The obtained positive electrode sheet has the characteristics of low porosity and high tap density, and further enables the finally obtained membrane electrode to have excellent performance.

[0064] Further preferably, the conditions for the first hot pressing include: a line load of 300 - 480 N / mm, a temperature of 75 - 90 °C, and a roller speed of 4 - 10 m / min; the conditions for the first laminating include: a line load of 220 - 280 N / mm, a temperature of 85 - 95 °C, and a roller speed of 4 - 10 m / min

[0065] According to the present invention, the conditions for the second hot pressing include: a line load of 100 - 400 N / mm, a temperature of 60 - 100 °C, and a roller speed of 2 m / min - 16 m / min; the conditions for the second laminating include: a line load of 50 - 100 N / mm, a temperature of 80 - 100 °C, and a roller speed of 2 m / min - 16 m / min.

[0066] In the present invention, under the above second hot pressing conditions, the electrolyte component is prepared into a film, and under the second laminating conditions, the electrolyte component film is laminated with the positive electrode sheet to obtain a membrane electrode. The obtained membrane electrode has good contact between the positive electrode and the electrolyte, and the interfacial impedance between the two is low. Moreover, the positive electrode is no longer directly exposed to the air, which can reduce the influence of water, oxygen, carbon dioxide, etc. in the environment on the positive electrode. Furthermore, the solid-state lithium battery prepared from the membrane electrode has excellent performance.

[0067] Further preferably, the conditions for the second hot pressing include: a line load of 180 - 300 N / mm, a temperature of 70 - 90 °C, and a roller speed of 6 - 12 m / min; the conditions for the second laminating include: a line load of 75 - 90 N / mm, a temperature of 85 - 95 °C, and a roller speed of 6 - 12 m / min.

[0068] In the present invention, the first hot pressing conditions and the second hot pressing conditions may be the same or different.

[0069] In the present invention, the mixing of the cathode component or the electrolyte component can be carried out through a high-shear and / or high-pressure process to obtain a uniform mixture. Preferably, the above-mentioned high-shear and / or high-pressure process can be carried out in equipment such as a jet mill, a colloid mill, a mechanical mill, a high-energy ball mill, etc. In the present invention, the cathode component or the electrolyte component can be made into a film by a hot press and the fitting between the current collector, the cathode, the electrolyte, and the anode can be achieved.

[0070] The third aspect of the present invention provides a membrane electrode prepared by the above preparation method.

[0071] The fourth aspect of the present invention provides a solid-state lithium battery, the solid-state lithium battery includes a lithium anode and a membrane electrode, and is characterized in that the membrane electrode is the above-mentioned membrane electrode.

[0072] According to the present invention, the lithium anode is selected from a lithium-copper composite structure and / or a lithium-nickel composite structure.

[0073] According to the present invention, the energy density of the lithium battery is 150-500 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles; the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.62.

[0074] According to the present invention, when the cathode material is a lithium cobalt oxide cathode material, the energy density of the lithium battery under the condition of 2.5-4.7V is 300-450 Wh / kg, the capacity retention rate is greater than 94.2% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.85.

[0075] According to the present invention, when the cathode material is a lithium manganese oxide cathode material, the energy density of the lithium battery under the condition of 2.5-4.5V is 150-280 Wh / kg, the capacity retention rate is greater than 93.5% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.82.

[0076] According to the present invention, when the cathode material is a multi-component cathode material, the energy density of the lithium battery under the condition of 2.5-4.5V is 270-400 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.80.

[0077] According to the present invention, when the cathode material is a lithium-rich manganese-based cathode material, the energy density of the lithium battery under the condition of 2-5V is 270-400 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.62.

[0078] According to the present invention, when the positive electrode material is an olivine positive electrode material, the energy density of the lithium battery under the conditions of 2.5 - 4V is 180 - 260 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.85.

[0079] The fifth aspect of the present invention provides a method for preparing a solid-state lithium battery, which is characterized in that the method includes the following steps:

[0080] S1. In an argon atmosphere with a water content ≤ 10 ppm and an oxygen content ≤ 10 ppm, the lithium negative electrode and the membrane electrode are laminated and cut to obtain battery cells;

[0081] S2. At least two battery cells are stacked, the electrode tabs are welded, and the housing is encapsulated to obtain the solid-state lithium battery.

[0082] In the present invention, in an argon atmosphere with a low water content and a low oxygen content, the lithium negative electrode and the membrane electrode are laminated and cut to obtain battery cells, which can reduce the side reactions between water and oxygen and other components, so that the prepared solid-state lithium battery has more excellent effects.

[0083] Further, in step S1, more excellent technical effects can be obtained when the water content ≤ 1 ppm and the oxygen content ≤ 1 ppm.

[0084] In the present invention, the lithium negative electrode and the membrane electrode are laminated and cut step by step to obtain multiple battery cells. Preferably, the rolling slicing method is used for cutting. Compared with the reciprocating punching process, it can extend the service life of the die, reduce the generation of dust, and the battery manufacturing environment is clean; at the same time, burrs can be reduced and the safety of the battery can be improved.

[0085] In the present invention, as Figure 1 shown, the cutting process includes: the first step of longitudinal discontinuous cutting, the second step of transverse cutting of the electrode tab, and the third step of final forming transverse cutting. Among them, the solid line is the first step of longitudinal discontinuous cutting, the dashed line is the transverse cutting of the electrode tab, and the dotted line is the final forming transverse cutting.

[0086] The present invention will be described in detail below through examples.

[0087] The raw materials involved in the present invention are purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and the solvents are purchased from Beijing Tongguang Fine Chemical Co., Ltd.

[0088] Charge and discharge cycle test: Charge to 4.3V with a charging current of 0.1C on a charge and discharge tester, switch to constant voltage charging until the charging current ≤ 0.01C, and then discharge to 3.0V with a discharge current of 0.1C to form 2 cycles, and then repeat the charge and discharge with a current of 0.2C to obtain the battery capacity retention rate graph.

[0089] The porosity of the membrane electrode was measured by mercury intrusion method;

[0090] The tap density of the membrane electrode was calculated by measuring the mass and volume of the membrane electrode;

[0091] The peel strength of the membrane electrode refers to the national standard GBT 2792-2014;

[0092] The energy density of the lithium battery is the ratio of the energy after the battery is fully charged to the mass; the cycle life is the number of cycles when the 0.5C charge-discharge capacity retention rate is greater than 80%.

[0093] Example 1

[0094] Step 1: The cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI and polyethylene oxide were mixed evenly in a jet mill according to the mass ratio of 83:5:3:9, and a 60-μm-thick cathode film was obtained using a hot press. Then, the cathode film was laminated onto an aluminum foil to obtain a cathode sheet. Among them, the hot pressing conditions were: linear load 350 N / mm, temperature 80 °C, roller speed 5.2 m / min; the lamination conditions were: linear load 240 N / mm, temperature 85 °C, roller speed 6 m / min.

[0095] Step 2: Polyethylene oxide, polypropylene carbonate, LiTFSI and Li 10 GeP2S 12 were mixed evenly in a high-energy ball mill according to the mass ratio of 65:5:15:15, and a 20-μm-thick electrolyte film was obtained using a hot press. Then, the electrolyte film was laminated onto the cathode sheet in sequence to obtain a membrane electrode M1. Among them, the hot pressing conditions were: linear load 220 N / mm, temperature 80 °C, roller speed 8 m / min; the lamination conditions were: linear load 80 N / mm, temperature 87 °C, roller speed 8 m / min. After testing, the porosity of the membrane electrode M1 was 7.6%, the tap density was 4 g / cm 3 , and the peel strength was 657 N / m.

[0096] Step 3: Under an argon atmosphere with both water content and oxygen content less than 10 ppm, the lithium-copper composite film was roll-pressed onto the membrane electrode, and a laminated battery cell was obtained by stepwise cutting; then stacking, welding the tabs, and casing encapsulation were carried out to obtain a solid-state battery.

[0097] The assembled battery was subjected to charge-discharge cycle testing at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example was 310 Wh / kg, the ratio of 2C rate discharge capacity to 0.1C rate discharge capacity was 0.86, and the capacity retention rate after 100 cycles was 91.3%, as Figure 2 shown. ByFigure 2 It can be seen that the solid-state battery prepared by the dry method has better cycle performance.

[0098] Example 2

[0099] Step 1: Mix the cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, polyethylene oxide, and polytetrafluoroethylene evenly in a jet mill according to the mass ratio of 83:5:3:4:5. Use a hot press to obtain a 60-μm-thick cathode film, and then attach the cathode film to an aluminum foil to obtain a cathode sheet. Among them, the hot pressing conditions are: line load 350 N / mm, temperature 80 °C, roller speed 5.2 m / min; the attachment conditions are: line load 240 N / mm, temperature 85 °C, roller speed 6 m / min.

[0100] Step 2: Mix polyethylene oxide, polypropylene carbonate, LiTFSI, and Li 10 GeP2S 12 evenly in a high-energy ball mill according to the mass ratio of 65:5:15:15. Use a hot press to obtain a 20-μm-thick electrolyte film, and then sequentially attach the electrolyte film to the cathode sheet to obtain a membrane electrode M2. Among them, the hot pressing conditions are: line load 220 N / mm, temperature 80 °C, roller speed 8 m / min; the attachment conditions are: line load 80 N / mm, temperature 87 °C, roller speed 8 m / min. After testing, the porosity of the membrane electrode M2 is 7.6%, the compaction density is 4 g / cm 3 , and the peel strength is 711 N / m..

[0101] Step 3: Under an argon atmosphere with both the water content and oxygen content less than 10 ppm, roll the lithium-copper composite film onto the membrane electrode, and stepwise cut it to obtain a laminated battery cell; then stack, weld the tabs, and encapsulate the shell to obtain a solid-state battery.

[0102] Perform charge-discharge cycle tests on the assembled battery at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example is 312 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is 0.85, and the capacity retention rate after 100 cycles is 92.2%.

[0103] Example 3

[0104] Step 1: Mix the cathode material (LiNi 0.8 Co 0.1 Mn 0.1O2), acetylene black, LiFSI, and polyethylene oxide were mixed evenly in a jet mill at a mass ratio of 83:5:3:9. A 60-μm-thick positive electrode film was obtained using a hot press, and then the positive electrode film was laminated onto an aluminum foil to obtain a positive electrode sheet. Among them, the hot pressing conditions were: line load 350 N / mm, temperature 80 °C, and roller speed 5.2 m / min; the lamination conditions were: line load 240 N / mm, temperature 85 °C, and roller speed 6 m / min.

[0105] Step 2: Polyethylene oxide, polypropylene carbonate, LiTFSI, and Li 10 GeP2S 12 were mixed evenly in a high-energy ball mill at a mass ratio of 65:5:15:15. A 20-μm-thick electrolyte film was obtained using a hot press, and then the electrolyte film was laminated onto the positive electrode sheet in sequence to obtain a membrane electrode M3. Among them, the hot pressing conditions were: line load 220 N / mm, temperature 80 °C, and roller speed 8 m / min; the lamination conditions were: line load 80 N / mm, temperature 87 °C, and roller speed 8 m / min. After testing, the porosity of the membrane electrode M3 was 7.6%, the compaction density was 4 g / cm 3 ³, and the peel strength was 657 N / m.

[0106] Step 3: Under an argon atmosphere with a water content and an oxygen content both less than 1 ppm, a lithium-copper composite film was roll-pressed onto the membrane electrode, and then step-by-step cutting was performed to obtain a stacked battery cell; subsequently, stacking, welding of the tabs, and housing encapsulation were carried out to obtain a solid-state battery.

[0107] The assembled battery was subjected to charge-discharge cycle testing at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example was 310 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate was 0.86, and the capacity retention rate after 100 cycles was 93.5%.

[0108] Example 4

[0109] Step 1: The positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide were mixed evenly in a jet mill at a mass ratio of 83:5:3:9. A 60-μm-thick positive electrode film was obtained using a hot press, and then the positive electrode film was laminated onto an aluminum foil to obtain a positive electrode sheet. Among them, the hot pressing conditions were: line load 400 N / mm, temperature 80 °C, and roller speed 5.2 m / min; the lamination conditions were: line load 240 N / mm, temperature 85 °C, and roller speed 6 m / min.

[0110] Step 2: Polyethylene oxide, polypropylene carbonate, LiTFSI, and Li 10 GeP2S 12Mix them evenly in a high-energy ball mill according to the mass ratio of 65:5:15:15, and use a hot press to obtain an electrolyte membrane with a thickness of 20 μm. Then, attach the electrolyte membrane to the positive electrode sheet in sequence to obtain a membrane electrode M4. Among them, the conditions for hot pressing are: line load 220 N / mm, temperature 80 °C, and roller speed 8 m / min; the conditions for attachment are: line load 80 N / mm, temperature 87 °C, and roller speed 8 m / min. After testing, the porosity of the membrane electrode M4 is 6.4%, and the compaction density is 4.1 g / cm 3 , and the peel strength is 668 N / m.

[0111] Step 3: Under an argon atmosphere with a water content and an oxygen content both less than 10 ppm, roll the lithium copper composite film onto the membrane electrode, and cut it step by step to obtain a stacked battery cell; then stack, weld the tabs, and encapsulate the shell to obtain a solid-state battery.

[0112] Perform charge-discharge cycle tests on the assembled battery at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example is 330 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is 0.82, and the capacity retention rate after 100 cycles is 91.5%.

[0113] Example 5

[0114] Step 1: Mix the positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide evenly in a jet mill according to the mass ratio of 83:5:3:9, and use a hot press to obtain a positive electrode membrane with a thickness of 60 μm. Then, attach the positive electrode membrane to the aluminum foil to obtain a positive electrode sheet. Among them, the conditions for hot pressing are: line load 350 N / mm, temperature 80 °C, and roller speed 5.2 m / min; the conditions for attachment are: line load 240 N / mm, temperature 85 °C, and roller speed 6 m / min.

[0115] Step 2: Mix polyethylene oxide, PEG200DA (containing 0.8 wt% azobisisobutyronitrile), LiTFSI, and Li 6.4 La3Zr 1.4 Nb 0.6 O 12 evenly in a high-energy ball mill according to the mass ratio of 40:30:15:15, and use a hot press to obtain an electrolyte membrane with a thickness of 20 μm. Then, attach the electrolyte membrane to the positive electrode sheet in sequence to obtain a membrane electrode M5. Among them, the conditions for hot pressing are: line load 220 N / mm, temperature 80 °C, and roller speed 8 m / min; the conditions for attachment are: line load 80 N / mm, temperature 87 °C, and roller speed 8 m / min. After testing, the porosity of the membrane electrode M5 is 7.2%, and the compaction density is 4 g / cm 3, The peel strength is 676 N / m.

[0116] Step 3: Under an argon atmosphere with both water content and oxygen content less than 10 ppm, roll the lithium copper composite film onto the membrane electrode, and stepwise cut it to obtain a stacked battery cell; then stack, weld the tabs, and encapsulate the case to obtain a solid-state battery.

[0117] The assembled battery was tested by charge-discharge cycling at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example is 311 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is 0.88, and the capacity retention rate after 100 cycles is 93.8%.

[0118] Example 6

[0119] Step 1: Mix the cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide evenly in a jet mill according to the mass ratio of 83:5:3:9, and use a hot press to obtain a 60-μm-thick cathode film, then attach the cathode film to an aluminum foil to obtain a cathode sheet. Among them, the hot pressing conditions are: linear load 350 N / mm, temperature 80 °C, roller speed 5.2 m / min; the attachment conditions are: linear load 240 N / mm, temperature 85 °C, roller speed 6 m / min.

[0120] Step 2: Mix polyethylene oxide, PEG200DA (containing 0.8 wt% azobisisobutyronitrile), LiTFSI, and Li 6.4 La3Zr 1.4 Nb 0.6 O 12 evenly in a high-energy ball mill according to the mass ratio of 40:30:15:15, and use a hot press to obtain a 20-μm-thick electrolyte film, then sequentially attach the electrolyte film to the cathode sheet to obtain a membrane electrode M6. Among them, the hot pressing conditions are: linear load 250 N / mm, temperature 75 °C, roller speed 8 m / min; the attachment conditions are: linear load 80 N / mm, temperature 87 °C, roller speed 8 m / min. After testing, the porosity of the membrane electrode M6 is 7.2%, and the compaction density is 4 g / cm 3 , The peel strength is 680 N / m.

[0121] Step 3: Under an argon atmosphere with both water content and oxygen content less than 10 ppm, roll the lithium copper composite film onto the membrane electrode, and stepwise cut it to obtain a stacked battery cell; then stack, weld the tabs, and encapsulate the case to obtain a solid-state battery.

[0122] The assembled battery was subjected to charge-discharge cycle testing at 60 °C. After testing, the solid-state lithium battery prepared in this example had an energy density of 313 Wh / kg, a ratio of 2C rate discharge capacity to 0.1C rate discharge capacity of 0.89, and a capacity retention rate of 93.1% after 100 cycles.

[0123] Example 7

[0124] Step 1: The cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide were mixed evenly in an air jet mill according to a mass ratio of 83:5:3:9. A cathode film with a thickness of 60 μm was obtained using a hot press, and then the cathode film was laminated onto an aluminum foil to obtain a cathode sheet. Among them, the hot pressing conditions were: linear load 350 N / mm, temperature 80 °C, and roller speed 5.2 m / min; the lamination conditions were: linear load 240 N / mm, temperature 85 °C, and roller speed 6 m / min.

[0125] Step 2: Polyethylene oxide, PEG200DA (containing 0.8 wt% azobisisobutyronitrile), LiTFSI, and Li 6.4 La3Zr 1.4 Nb 0.6 O 12 were mixed evenly in a high-energy ball mill according to a mass ratio of 50:20:15:15. An electrolyte film with a thickness of 20 μm was obtained using a hot press, and then the electrolyte film was laminated onto the cathode sheet in sequence to obtain a membrane electrode M7. Among them, the hot pressing conditions were: linear load 250 N / mm, temperature 75 °C, and roller speed 8 m / min; the lamination conditions were: linear load 80 N / mm, temperature 87 °C, and roller speed 8 m / min. After testing, the porosity of the membrane electrode M7 was 7.2%, the compaction density was 4.0 g / cm 3 , and the peel strength was 669 N / m.

[0126] Step 3: Under an argon atmosphere with a water content and an oxygen content both less than 10 ppm, a lithium-copper composite film was roll-pressed onto the membrane electrode, and then cut step by step to obtain a stacked battery cell; subsequently, stacking, welding the tabs, and casing encapsulation were carried out to obtain a solid-state battery.

[0127] The assembled battery was subjected to charge-discharge cycle testing at 60 °C. After testing, the solid-state lithium battery prepared in this example had an energy density of 316 Wh / kg, a ratio of 2C rate discharge capacity to 0.1C rate discharge capacity of 0.90, and a capacity retention rate of 90.3% after 100 cycles.

[0128] Example 8

[0129] Step 1: The cathode material (LiNi 0.8 Co0.1 Mn 0.1 O₂), acetylene black, LiFSI and polyethylene oxide are mixed evenly in a jet mill according to a mass ratio of 83:5:3:9, and a 60-μm-thick positive electrode film is obtained using a hot press. Then, the positive electrode film is laminated onto an aluminum foil to obtain a positive electrode sheet. Among them, the hot pressing conditions are: linear load 350 N / mm, temperature 80 °C, roller speed 5.2 m / min; the lamination conditions are: linear load 240 N / mm, temperature 85 °C, roller speed 6 m / min.

[0130] Step 2: Polyethylene oxide, poly(ethylene carbonate), LiTFSI and Li 6.4 La₃Zr 1.4 Nb 0.6 O 12 are mixed evenly in a high-energy ball mill according to a mass ratio of 10:30:10:50, and a 20-μm-thick electrolyte film is obtained using a hot press. Then, the electrolyte film is successively laminated onto the positive electrode sheet to obtain a membrane electrode M8. Among them, the hot pressing conditions are: linear load 250 N / mm, temperature 75 °C, roller speed 8 m / min; the lamination conditions are: linear load 80 N / mm, temperature 87 °C, roller speed 8 m / min. After testing, the porosity of the membrane electrode M8 is 7.7%, the tap density is 4 g / cm 3 , and the peel strength is 690 N / m.

[0131] Step 3: Under an argon atmosphere with a water content and an oxygen content both less than 10 ppm, a lithium copper composite film is roll-pressed onto the membrane electrode, and then step-by-step cutting is performed to obtain a stacked battery cell; subsequently, stacking, welding of the tabs, and housing encapsulation are carried out to obtain a solid-state battery.

[0132] The assembled battery is subjected to charge-discharge cycle testing at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example is 305 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is 0.91, and the capacity retention rate after 100 cycles is 94.7%.

[0133] Example 9

[0134] Step 1: The positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O₂), acetylene black, LiFSI and polyethylene oxide are mixed evenly in a jet mill according to a mass ratio of 83:5:3:9, and a 60-μm-thick positive electrode film is obtained using a hot press. Then, the positive electrode film is laminated onto an aluminum foil to obtain a positive electrode sheet. Among them, the hot pressing conditions are: linear load 300 N / mm, temperature 80 °C, roller speed 5.2 m / min; the lamination conditions are: linear load 200 N / mm, temperature 85 °C, roller speed 6 m / min.

[0135] Step 2: Mix polyethylene oxide, poly(propylene carbonate), LiTFSI, and Li 10 GeP2S 12 uniformly in a high-energy ball mill according to a mass ratio of 65:5:15:15, and use a hot press to obtain an electrolyte membrane with a thickness of 20 μm. Then, attach the electrolyte membrane to the positive electrode sheet in sequence to obtain a membrane electrode M9. Among them, the hot pressing conditions are: linear load of 220 N / mm, temperature of 80 °C, and roller speed of 8 m / min; the attachment conditions are: linear load of 80 N / mm, temperature of 87 °C, and roller speed of 8 m / min. After testing, the porosity of the membrane electrode M9 is 12.6%, the tap density is 3.8 g / cm 3 , and the peel strength is 680 N / m.

[0136] Step 3: Under an argon atmosphere with a water content and an oxygen content both less than 10 ppm, roll the lithium copper composite film onto the membrane electrode, and cut it step by step to obtain a stacked battery cell; then stack, weld the tabs, and encapsulate the case to obtain a solid-state battery.

[0137] Perform charge-discharge cycle tests on the assembled battery at 60 °C. After testing, the energy density of the solid-state lithium battery prepared in this example is 303 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is 0.82, and the capacity retention rate after 100 cycles is 90.6%.

[0138] Comparative Example 1

[0139] Step 1: Mix the positive electrode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide uniformly in a stirrer according to a mass ratio of 83:5:3:9 and an appropriate amount of N-methyl-2-pyrrolidone, and coat it on an aluminum foil, and dry it at 130 °C for 0.5 h to obtain a positive electrode sheet, where the thickness of the positive electrode membrane is 60 μm.

[0140] Step 2: Mix polyethylene oxide, poly(propylene carbonate), LiTFSI, and Li 10 GeP2S 12 uniformly in a high-energy ball mill according to a mass ratio of 65:5:15:15, and use a hot press to obtain an electrolyte membrane with a thickness of 20 μm. Then, attach the electrolyte membrane to the positive electrode sheet in sequence to obtain a membrane electrode DM1. Among them, the hot pressing conditions are: linear load of 220 N / mm, temperature of 80 °C, and roller speed of 8 m / min; the attachment conditions are: linear load of 80 N / mm, temperature of 87 °C, and roller speed of 8 m / min. After testing, the porosity of the membrane electrode DM1 is 20.1%, the tap density is 3.6 g / cm 3 , and the peel strength is 464 N / m.

[0141] The operations in Step 3 and the tests are the same as those in Example 1 and will not be elaborated here.

[0142] The assembled battery was subjected to charge-discharge cycle tests at 60°C. After testing, the energy density of the solid-state lithium battery prepared in Comparative Example 1 was 243 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate was 0.68, and the capacity retention rate after 100 cycles was 77.3%. It can be seen that Figure 2 compared with the solid-state battery prepared by the dry method, the battery in this example has a faster cycle decay.

[0143] Comparative Example 2

[0144] Step 1: The cathode material (LiNi 0.8 Co 0.1 Mn 0.1 O2), acetylene black, LiFSI, and polyethylene oxide were mixed evenly in a jet mill according to a mass ratio of 83:5:3:9. A cathode film with a thickness of 60 μm was obtained using a hot press, and then the cathode film was laminated onto an aluminum foil to obtain a cathode sheet. Among them, the hot-pressing conditions were: linear load 350 N / mm, temperature 80°C, and roller speed 5.2 m / min; the lamination conditions were: linear load 240 N / mm, temperature 85°C, and roller speed 6 m / min.

[0145] Step 2: Polyethylene oxide, poly(propylene carbonate), LiTFSI, and Li 10 GeP2S 12 were dissolved in an appropriate amount of N-methyl-2-pyrrolidone according to a mass ratio of 65:5:15:15 to obtain a uniformly dispersed electrolyte slurry. The above electrolyte slurry was doctor-bladed onto the cathode sheet using a coater, dried in a blast oven at 60°C for 24 h, and then dried in a vacuum at 60°C for 5 h to obtain a membrane electrode DM2, where the thicknesses of the cathode film and the electrolyte film were 60 μm and 15 μm, respectively. After testing, the porosity of the membrane electrode DM1 was 4.2%, the tap density was 4 g / cm 3 3, and the peel strength was 853 N / m.

[0146] The operations in Step 3 and the tests are the same as those in Example 1 and will not be elaborated here.

[0147] The assembled battery was subjected to charge-discharge cycle tests at 60°C. After testing, the energy density of the solid-state lithium battery prepared in Comparative Example 2 was 208 Wh / kg, the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate was 0.51, and the capacity retention rate after 100 cycles was 65.1%.

[0148] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A membrane electrode, characterized in that, The membrane electrode sequentially includes a current collector, at least one positive electrode layer, and at least one electrolyte layer; The porosity of the membrane electrode is 6.4% - 15%, and the tap density is 2.5 g / cm 3 - 4.8 g / cm 3 , and the peel strength between the positive electrode layer and the electrolyte layer is 600 - 800 N / m; The preparation method of the membrane electrode includes the following steps: (1) Mix, knead, and perform first hot pressing on the positive electrode components to prepare a thin film, and perform first lamination with the current collector to obtain a positive electrode sheet; (2) Mix, knead, and perform second hot pressing on the electrolyte components to prepare a thin film, and perform second lamination with the positive electrode sheet obtained in step (1) to obtain the membrane electrode; Among them, the conditions of the first hot pressing include: the linear load is 200 - 600 N / mm, the temperature is 60 - 100 °C, and the roller speed is 2 m / min - 16 m / min; the conditions of the first lamination include: the linear load is 200 - 300 N / mm, the temperature is 80 - 100 °C, and the roller speed is 2 m / min - 16 m / min; Among them, the conditions of the second hot pressing include: the linear load is 50 - 500 N / mm, the temperature is 60 - 100 °C, and the roller speed is 2 m / min - 16 m / min; the conditions of the second lamination include: the linear load is 50 - 100 N / mm, the temperature is 80 - 100 °C, and the roller speed is 2 m / min - 16 m / min.

2. The membrane electrode according to claim 1, wherein The porosity of the membrane electrode is 6.4% - 10%; When the positive electrode layer is a lithium cobalt oxide positive electrode material, the tap density of the membrane electrode is 4.5 g / cm 3 - 4.8 g / cm 3 ; And / or, when the positive electrode layer is a lithium manganate positive electrode material, the tap density of the membrane electrode is 3.5 g / cm 3 - 3.9 g / cm 3 ; And / or, when the positive electrode layer is a multi-component positive electrode material, the tap density of the membrane electrode is 3.9 g / cm 3 - 4.5 g / cm 3 ; And / or, when the positive electrode layer is an olivine positive electrode material, the compaction density of the membrane electrode is 2.5 g / cm 3 -3.2 g / cm 3 ; And / or, when the positive electrode layer is a lithium-rich manganese-based positive electrode material, the tap density of the membrane electrode is 2.6 g / cm 3 - 3 g / cm 3 ; And / or, the peel strength between the positive electrode layer and the electrolyte layer is 650 - 750 N / m.

3. A method for preparing the membrane electrode according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Mix, knead, and perform first hot pressing on the positive electrode components to prepare a thin film, and perform first lamination with the current collector to obtain a positive electrode sheet; (2) Mix, knead, and perform second hot pressing on the electrolyte components to prepare a thin film, and perform second lamination with the positive electrode sheet obtained in step (1) to obtain the membrane electrode; Among them, the conditions of the first hot pressing include: the linear load is 200 - 600 N / mm, the temperature is 60 - 100 °C, and the roller speed is 2 m / min - 16 m / min; the conditions of the first lamination include: the linear load is 200 - 300 N / mm, the temperature is 80 - 100 °C, and the roller speed is 2 m / min - 16 m / min.

4. The preparation method according to claim 3, wherein In step (1), the positive electrode components include a positive electrode active material, a conductive agent, a lithium salt, and a binder; And / or, the current collector is aluminum foil.

5. The preparation method according to claim 4, wherein In step (1), the mass ratio of the positive electrode active material, the conductive agent, the lithium salt, and the binder is 65 - 98:0.5 - 10:0.5 - 10:1 - 15; And / or, the current collector is a mesh aluminum foil and / or a carbon-coated aluminum foil.

6. The preparation method according to claim 5, wherein, In step (1), the mass ratio of the positive electrode active material, the conductive agent, the lithium salt, and the binder is 70 - 92:1 - 5:1 - 5:2 - 10.

7. The preparation method according to claim 4, wherein, The positive electrode active material is selected from at least one of lithium cobaltate, lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium manganese iron phosphate, lithium manganese phosphate, and lithium-rich manganese-based materials; And / or, the conductive agent is selected from at least one of Super P, acetylene black, graphite, KS-6, carbon nanotubes, graphene, carbon fiber, and activated carbon; And / or, the lithium salt is selected from at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, and lithium difluoro(oxalato)borate.

8. The preparation method according to claim 4, wherein The binder is selected from small molecule organic compounds and / or high molecular polymers, and the mass ratio of the small molecule organic compound to the high molecular polymer is 0:100 - 100:

0.

9. The preparation method according to claim 8, wherein, The mass ratio of the small molecule organic compound to the high molecular polymer is 20 - 80:80 - 20; And / or, the small molecule organic compound is selected from acrylate compounds and / or vinyl ester compounds; And / or, the high molecular polymer is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, (vinylidene fluoride - hexafluoropropylene) copolymer, polyethylene oxide, polydimethylsiloxane, polymethyl methacrylate, polypropylene carbonate, poly(ethylene carbonate), and polycaprolactone.

10. The preparation method according to claim 9, wherein, The small molecule organic compound is selected from at least one of dimethyl polyethylene glycol ether, dimethyl triethylene glycol ether, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, dimethyl triethylene glycol ether, and trimethylolpropane triacrylate.

11. According to the preparation method described in claim 3, wherein, In step (2), the electrolyte component includes an organic compound, a lithium salt, and an inorganic nano - powder.

12. The preparation method according to claim 11, wherein, Based on the total weight of the electrolyte component, the dosage of the organic compound is 5 - 90 wt%, the dosage of the lithium salt is 5 - 50 wt%, and the content of the inorganic nano - powder is 0 - 90 wt%.

13. According to the preparation method described in claim 12, wherein, Based on the total weight of the electrolyte component, the dosage of the organic compound is 10 - 80 wt%, the dosage of the lithium salt is 10 - 36 wt%, and the content of the inorganic nano - powder is 10 - 70 wt%.

14. The preparation method according to claim 11, wherein, The organic compound is selected from small molecule organic compounds and / or high molecular polymers, and the mass ratio of the small molecule organic compound to the high molecular polymer is 0:100 - 100:

0.

15. The preparation method according to claim 14, wherein, The mass ratio of the small molecule organic compound to the high molecular polymer is 20 - 80:80 - 20; And / or, the small molecule organic compound is selected from acrylate compounds and / or ether compounds; And / or, the high molecular polymer is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, (vinylidene fluoride - hexafluoropropylene) copolymer, polyethylene oxide, polydimethylsiloxane, polymethyl methacrylate, polypropylene carbonate, poly(ethylene carbonate), and polycaprolactone; And / or, the lithium salt is selected from at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, and lithium difluoro(oxalato)borate; And / or, the inorganic nano powder is selected from silicon dioxide, titanium dioxide, aluminum oxide, lithium aluminum titanium phosphate, lithium aluminum lanthanum zirconate, lithium niobium lanthanum zirconate, lithium lanthanum titanate, Li 10 GeP2S 12 , Li2S-P2S5, Li3InCl3Br3, Li3InCl6, Li3InBr6, Li2InCa 0.5 Br6 and Li 2.8 Y 0.8 Zr 0.2 Cl 5.4 Br 0.4 and at least one of the following.

16. The preparation method according to claim 15, wherein The small molecule organic compound is selected from at least one of dimethyl polyethylene glycol ether, dimethyl triethylene glycol ether, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, dimethyl triethylene glycol ether, and trimethylolpropane triacrylate.

17. A solid-state lithium battery, the solid-state lithium battery comprising a lithium negative electrode and a membrane electrode, characterized in that, The membrane electrode is the membrane electrode according to claim 1 or 2.

18. The solid-state lithium battery according to claim 17, wherein, The lithium negative electrode is selected from a lithium - copper composite structure and / or a lithium - nickel composite structure.

19. The solid-state lithium battery according to claim 17 or 18, wherein, The energy density of the lithium battery is 150 - 500 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.

62.

20. The solid-state lithium battery according to claim 17 or 18, wherein, When the cathode material is lithium cobalt oxide cathode material, the energy density of the lithium battery under the condition of 2.5 - 4.7V is 300 - 450 Wh / kg, the capacity retention rate is greater than 94.2% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.85; and / or, when the cathode material is lithium manganate cathode material, the energy density of the lithium battery under the condition of 2.5 - 4.5V is 150 - 280 Wh / kg, the capacity retention rate is greater than 93.5% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.82; and / or, when the cathode material is a multi-component cathode material, the energy density of the lithium battery under the condition of 2.5 - 4.5V is 270 - 400 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.80; and / or, when the cathode material is a lithium-rich manganese-based cathode material, the energy density of the lithium battery under the condition of 2 - 5V is 270 - 400 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.62; and / or, when the cathode material is an olivine cathode material, the energy density of the lithium battery under the condition of 2.5 - 4V is 180 - 260 Wh / kg, the capacity retention rate is greater than 90% after 100 cycles, and the ratio of the discharge capacity at 2C rate to the discharge capacity at 0.1C rate is greater than 0.

85.

21. A method for preparing a solid-state lithium battery according to any one of claims 17-20, characterized in that, The method includes the following steps: S1. In an argon atmosphere with a water content ≤ 10 ppm and an oxygen content ≤ 10 ppm, the lithium negative electrode and the membrane electrode are bonded and cut to obtain a battery unit; S2. At least two battery units are stacked, the electrode tabs are welded, and the housing is encapsulated to obtain the solid-state lithium battery.

22. The method according to claim 21, wherein, In step S1, the water content is ≤ 1 ppm and the oxygen content is ≤ 1 ppm; and / or, the cutting is rolling slicing.

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