All-solid-state metal lithium battery and preparation method thereof

Abstract

The invention provides an all-solid-state metal lithium battery and a preparation method thereof. The all-solid-state metal lithium battery comprises a positive electrode, a solid electrolyte and a negative electrode which are sequentially stacked, and the negative electrode is a lithium composite negative electrode and comprises a modified graphitized membrane material serving as a current collector; the active substance layer is compounded on the surface of the modified graphitized membrane material, and the active substance layer is metal lithium or lithium alloy foil which is continuously or intermittently distributed; and the lithium storage supplement layer is formed by diffusing lithium atoms into the modified graphitized membrane material. According to the all-solid-state metal lithium battery negative electrode, the modified graphitized membrane material and the metal lithium are used for forming the negative electrode, due to the fact that the densities of the modified graphitized membrane material and the metal lithium are small, and due to the existence of the lithium storage supplementing layer, the obtained all-solid-state battery is high in energy density and long in cycle life.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more specifically, to an all-solid-state lithium metal battery and its preparation method. Background Technology

[0002] Lithium-ion rechargeable batteries, as a type of battery capable of repeated charging and discharging, are widely used in 3C products, new energy vehicles, energy storage power stations, and other fields. With the increasing demand for longer driving range, the energy density of existing lithium-ion batteries (generally below 200Wh / kg) cannot meet the need for higher energy densities.

[0003] Lithium metal anodes are characterized by their low density (0.534 g / cm³). 3 The highest theoretical specific capacity (3860 mAh / g) and the lowest electrochemical potential (-3.04 V VS. standard hydrogen electrode) have always been a research hotspot, making it the preferred anode for high energy density (>300 Wh / kg) secondary batteries.

[0004] Using self-supporting lithium strips as the negative electrode results in the highest specific energy of the battery cell. However, lithium strip products with a thickness of less than 50µm are unsuitable for automated roll forming due to the material's softness and low tensile strength. There is an urgent need to find a lightweight material that can support the automated roll forming production of metallic lithium.

[0005] Currently, liquid lithium-ion batteries use electrolytes with low flash points and high volatility. When the battery experiences an internal short circuit or is subjected to mechanical impact, it is prone to thermal runaway, leading to safety accidents. On the other hand, in current solid-state batteries, the transport of lithium ions and electrons is through solid-solid conduction, resulting in a very short cycle life, rarely exceeding 50 cycles.

[0006] In conclusion, developing a long-life all-solid-state lithium metal battery is of paramount importance. Summary of the Invention

[0007] The purpose of this invention is to provide an all-solid-state lithium metal battery and its preparation method. This all-solid-state lithium metal battery employs a modified graphitized composite anode, which is formed by laminating continuously or intermittently distributed lithium metal or lithium alloy foils onto the surface of a modified graphitized film. Lithium atoms can diffuse into the modified graphitized film during the hot-pressing process to form a lithium storage replenishment layer. This anode has a tensile strength greater than 15 MPa, facilitating industrial production. Furthermore, the presence of the lithium storage replenishment layer contributes to extending the battery's cycle life in the later stages of cycling.

[0008] According to one aspect of the present invention, an all-solid-state lithium metal battery is provided, the all-solid-state lithium metal battery comprising:

[0009] positive electrode;

[0010] Solid electrolytes; and

[0011] Negative electrode, wherein the negative electrode is a lithium composite negative electrode, comprising:

[0012] Modified graphitized film material as a current collector;

[0013] An active material layer is composited on the surface of the modified graphitized film, wherein the active material...

[0014] The substrate is a continuous or intermittently distributed metallic lithium or lithium alloy foil; and

[0015] A lithium storage replenishment layer formed by the diffusion of lithium atoms into the modified graphitized film material.

[0016] The positive electrode, solid electrolyte, and negative electrode are stacked or wrapped in sequence, and the active material layer of the negative electrode is in contact with the solid electrolyte.

[0017] According to certain preferred embodiments of the present invention, the positive electrode active material in the positive electrode comprises one or more of lithium iron phosphate, lithium-rich manganese-based materials, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, vanadium pentoxide, manganese dioxide, sulfur carbon, sulfurized polyacrylonitrile, iron disulfide and oxygen.

[0018] According to certain preferred embodiments of the present invention, the solid electrolyte comprises one or more of sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, and polymer solid electrolytes.

[0019] According to certain preferred embodiments of the present invention, the lithium metal battery may be a pouch battery, a cylindrical battery, or a steel-cased battery.

[0020] According to certain preferred embodiments of the present invention, the all-solid-state lithium metal battery anode meets the following requirements:

[0021] The modified graphitized membrane material includes graphite or graphitized organic polymer and modifier and structural reinforcing agent, or is obtained by graphitization treatment of a membrane material made of graphene, modifier and structural reinforcing agent, wherein the modifier is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers, the structural reinforcing agent is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid, and the organic polymer is selected from polyimide or polyacrylonitrile;

[0022] The graphitization treatment is carried out at a temperature of 2300-3000℃ for 0.5-2 hours.

[0023] The modifier accounts for 0.1%-10% by mass, and the structural reinforcing agent accounts for 0.1%-10% by mass;

[0024] The thickness of the lithium storage replenishment layer is 0.5-25 μm; preferably greater than 2 μm, more preferably greater than 5 μm;

[0025] The sheet resistance of the modified graphitized film is 0.1-100 mΩ / cm. 2 The membrane material thickness is 5-25μm, and the membrane density is 1.3-2.0g / cm³. 3 The tensile strength of the membrane material is 15-100 MPa;

[0026] The thickness of the lithium metal or lithium alloy foil is 1-100 μm and the width is 50-1400 mm.

[0027] The lithium alloy foil is a foil material formed by combining metallic lithium with any one or at least two elements selected from Ag, Au, Sn, Si, Zn, Al, Mg, In, Ga, B, Mn, Sb, Cr, C, V, Cu, Fe, or Ti.

[0028] Both sides of the modified graphitized film are coated with an active material layer;

[0029] The release film is a polyethylene terephthalate, polypropylene, or polyethylene plastic film with a silicone oil coating on its surface.

[0030] According to another aspect of the present invention, a method for preparing an all-solid-state lithium metal battery is provided, the method comprising the following steps:

[0031] Step 1: Preparation of lithium composite anode;

[0032] Step 2: Preparation of the positive electrode: The positive electrode material is coated on the current collector using a dry or wet coating process to obtain the positive electrode layer;

[0033] Step 3: Preparation of solid electrolyte membrane: The polymer solid electrolyte or inorganic solid electrolyte and lithium salt are formed into a membrane by a dry process, or the polymer solid electrolyte or inorganic solid electrolyte, lithium salt and solvent are formed into a membrane by a wet process.

[0034] Step 4: The lithium composite anode, solid electrolyte membrane, and cathode are stacked or wound to form a battery cell, and the isostatic pressing process is used to make the layers in close contact.

[0035] According to certain preferred embodiments of the present invention, the lithium composite anode is prepared by the following steps:

[0036] Step 1: Prepare the modified graphitized film material, and roll it up together with one side of the release film;

[0037] Step 2: Unwind the lithium metal / lithium alloy foil and the modified graphitized film. Then, perform low-pressure bonding of the modified graphitized film with the side of the lithium metal / lithium alloy foil facing the side of the film without the release film attached. The pressure is set to 1-2 MPa. Remove the release film to obtain a single-sided lithium composite negative electrode.

[0038] Step 3: Unwind another roll of lithium metal / lithium alloy foil, and pressure bond the side of the single-sided lithium composite anode without composite lithium to the unwound lithium metal / lithium alloy foil. The pressure is set to 3-5 MPa to obtain a preliminary double-sided lithium composite anode.

[0039] Step 4: The preliminary double-sided lithium composite anode is rolled by hot rollers. The temperature of the hot rollers is 40-60℃ and the pressure is set to 1-2MPa to obtain the lithium composite anode.

[0040] Compared with the prior art in this field, the lithium metal battery of the present invention has at least the following advantages:

[0041] 1. The negative electrode of this all-solid-state lithium metal battery uses a lightweight graphitized film as a support material to enhance the tensile strength of the lithium metal itself, enabling automated production applications.

[0042] 2. Due to the presence of a lithium storage replenishment layer, the cycle life of this all-solid-state lithium metal battery is extended by about 10% in the later stages of cycling. Attached Figure Description

[0043] Figure 1 The figures show the battery cycle performance curves for the examples and comparative examples. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to specific embodiments. Other embodiments are considered and may be implemented without departing from the scope or spirit of the present invention. Therefore, the following detailed description is non-limiting.

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. The technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] Example

[0047] In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0048] Test methods

[0049] Tensile strength tests were performed on the negative electrode materials prepared in the following examples and comparative examples, and electrochemical performance (battery cycle) tests were performed on the lithium metal batteries prepared therefrom, according to the test methods described in detail below.

[0050] Tensile strength test

[0051] The negative electrode test strips prepared in the examples and comparative examples were 87.5 mm long and 12.5 mm wide. Three strips were cut for each material and tensile tests were performed on a tensile testing device (BT series, manufactured by Shenzhen Beite Instrument Equipment Co., Ltd.). Specifically, the test procedures were as follows:

[0052] GB-228-87 Metallic Materials - Tensile Testing Method. The results are shown in Table 1 below.

[0053] Battery Cycle Test

[0054] All-solid-state lithium metal batteries were assembled using the negative electrodes prepared in the following examples and comparative examples, respectively. Charge-discharge tests were performed on the assembled all-solid-state lithium metal batteries. The charge-discharge current was 7.5 mA, and the voltage range was 2.5-4.35 V. Cycling was continued until the end of the battery life, and the number of charge-discharge cycles was recorded. The test results show... Figure 1 .

[0055] Example 1:

[0056] Preparation of modified graphitized film materials:

[0057] Flake graphite powder was oxidized with concentrated sulfuric acid, the product was washed with water until neutral, and dried at low temperature to obtain product A. Product A, single-walled carbon nanotubes, and polyvinylidene fluoride resin were mixed at a mass ratio of 97.5:

[0058] Mix in a 1.5:1 ratio, add trace amounts of 1-methyl-2-pyrrolidone solvent, knead until uniform, and use a roller press with a pressure set to 3 MPa to prepare a graphitized film with a thickness of 20 μm. One side is bonded to a release film and rolled up together. The tensile strength of the film is 16.5 MPa.

[0059] Preparation of lithium composite anode 1:

[0060] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and the 20μm thick graphitized film prepared above are unwound and rolled together. Using a roller press, the pressure is set to 2MPa to obtain a preliminary single-sided lithium composite anode.

[0061] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0062] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 2 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain lithium composite anode 1 for use in batteries, with a lithium storage replenishment layer thickness of 5 μm.

[0063] The aforementioned lithium composite anode 1, cathode, and solid electrolyte are assembled into a lithium metal pouch battery. The cathode uses a high-nickel ternary cathode material (NCM811, already coated with sulfides); the solid electrolyte uses a sulfide solid electrolyte (Li). 10 GeP2S 12 ).

[0064] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0065] Example 2:

[0066] Preparation of modified graphitized film materials:

[0067] First, a polyimide polymer was synthesized. The polyimide was then carbonized at 1300℃ for 1 hour, followed by graphitization at 2600℃ for 1 hour to obtain the graphitized product (B). Product B, multi-walled carbon nanotubes, and polytetrafluoroethylene (powder, particle size less than 12μm, Aladdin) were mixed in a mass ratio of 97.5:1:1.5. A trace amount of 1-methyl-2-pyrrolidone was added and mixed evenly. A 17μm thick film was prepared using a roller press with a pressure of 5MPa. The film was then rolled up together with a PET plastic film coated with a thin layer of silicone oil to obtain a rolled graphitized film with a tensile strength of 20.1MPa.

[0068] Preparation of lithium composite anode 2:

[0069] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and a 17μm thick graphitized film prepared above are unwound and rolled together. Using a roller press with a pressure of 1MPa, a preliminary single-sided lithium composite anode is obtained.

[0070] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0071] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 50°C, and a rolling speed of 30 m / min to obtain lithium composite anode 2 (with a lithium storage supplement layer thickness of 10 μm) for use in batteries.

[0072] The aforementioned lithium composite anode 2, cathode, and solid electrolyte are assembled into a lithium metal pouch battery. The cathode uses a high-nickel ternary cathode material (NCM811); the solid electrolyte uses polyethylene oxide (PEO, average molecular weight 1.2 million) and Li7La3Zr2O. 12 Composite solid electrolyte.

[0073] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0074] Example 3:

[0075] The graphitized film material modified in Example 3 is the same as that in Example 2.

[0076] The 20μm thick lithium foil in Example 2 was replaced with a 20μm thick lithium-magnesium alloy foil (magnesium content of 5%). A roll of lithium-magnesium alloy foil and the 17μm thick graphitized film prepared above were unwound and rolled up. Using a roller press with the pressure set to 2MPa, a preliminary single-sided lithium composite anode was obtained.

[0077] Another 20μm thick lithium-magnesium alloy foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0078] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 45°C, and a rolling speed of 30 m / min to obtain lithium composite anode 3 (with a lithium storage supplement layer thickness of 10 μm) for use in batteries.

[0079] The aforementioned lithium composite anode 3, cathode, and solid electrolyte are assembled into a lithium metal pouch battery. The cathode uses a high-nickel ternary cathode material (NCM811); the solid electrolyte uses Li7La3Zr2O. 12 .

[0080] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0081] Example 4:

[0082] Preparation of modified graphitized film: A 5% solid content graphene oxide oily slurry was used, followed by a 0.4% solid content single-walled carbon nanotube slurry, and finally a 0.5% polyvinylidene fluoride slurry. The three were mixed thoroughly, with a graphene:single-walled carbon nanotube:polyvinylidene fluoride mass ratio of 98:1:1. The new slurry was applied to a PET plastic film coated with a thin silicone oil layer using a 250μm doctor blade, and then dried at 45 degrees Celsius for 10 hours to form a pre-dried graphene oxide film. The graphene oxide film was then transferred from the PET film... The ET plastic film is peeled off to obtain a self-supporting graphene oxide film. The graphene oxide film is then placed in a vitamin C solution (0.5 mol / L) for reduction at 80℃ for 24 hours to obtain a reduced graphene film. The reduced graphene film is further compacted under the protection of upper and lower film materials to obtain a shaped graphene film. The rolled graphene film is then subjected to a high-temperature treatment at 2500℃ for 30 minutes to obtain a graphitized film with a thickness of 12 μm and a tensile strength of 23.5 MPa.

[0083] Preparation of lithium composite anode 4:

[0084] The active material is a 20μm thick lithium foil in roll. A roll of lithium foil and a 12μm thick graphitized film prepared above are unwound and rolled together. Using a roller press, the pressure is set to 1.5MPa to obtain a preliminary single-sided lithium composite anode.

[0085] Another 20μm thick lithium foil and a preliminary single-sided lithium composite anode are unwound and pressed using a roller press with a pressure of 4MPa to obtain a preliminary double-sided lithium composite anode.

[0086] The initial double-sided lithium composite anode is then subjected to a hot rolling process with a pressure of 1 MPa, a temperature of 45°C, and a rolling speed of 40 m / min to obtain lithium composite anode 4 (with a lithium storage replenishment layer thickness of 7.5 μm) for use in batteries.

[0087] The above-mentioned lithium composite anode 4, cathode and solid electrolyte are assembled into a lithium metal pouch battery. The cathode uses a high-nickel ternary cathode material (NCM811); the solid electrolyte uses polyvinylidene fluoride-hexafluoropropylene copolymer and lithium bis(trifluoromethanesulfonamide) (LiTFSI) as the lithium salt.

[0088] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0089] Example 5: The lithium composite anode 3 of Example 3 was used, and the positive electrode was a high-nickel ternary positive electrode material (NCM811); the solid electrolyte was Li3YCl6 solid electrolyte.

[0090] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0091] Comparative Example 1:

[0092] Using 40µm lithium metal foil as the negative electrode, the 40µm thick pure lithium foil is easily bent and deformed during the unwinding and die-cutting process, and there is also the problem of tape breakage, resulting in an uneven surface of the electrode sheet, which cannot be used in continuous production.

[0093] Comparative Example 2:

[0094] The active material is a 20μm thick lithium foil in rolls. Two rolls of lithium foil and a 6μm thick copper foil are unwound and rolled up. The pressure is set to 3MPa using a roller press to obtain the lithium composite negative electrode 5.

[0095] The aforementioned lithium composite anode 5, cathode, and solid electrolyte are assembled into a lithium metal pouch battery. The cathode uses a high-nickel ternary cathode material (NCM811, already coated with sulfides); the solid electrolyte uses a sulfide solid electrolyte (Li). 10 GeP2S 12 ).

[0096] Based on the battery cycle testing method described above, the obtained all-solid-state lithium metal pouch battery was subjected to battery cycle testing, and the results showed... Figure 1 middle.

[0097] Table 1 Tensile strength values ​​of the negative electrode

[0098] name Average tensile strength (MPa) of three tests Example 1 (Lithium Composite Anode 1) 17.8 Example 2 (Lithium Composite Anode 2) 22.5 Example 3 (Lithium Composite Anode 3) 25.7 Example 4 (Lithium Composite Anode 4) 26.9 Comparative Example 1 (Lithium Metal Foil) 0.36

[0099] As can be seen from the table above, the lithium foil used in Comparative Example 1 has the lowest tensile strength, making it unsuitable for continuous production. The lithium composite anodes of Examples 1-4 all have tensile strengths greater than 15 MPa, allowing for continuous production.

[0100] Figure 1 Cycle curves of the all-solid-state lithium metal pouch cells prepared in Examples 1, 2, 3, 4, 5, and Comparative Example 2 of this invention are shown. From... Figure 1As can be seen, the discharge capacity of the all-solid-state lithium metal batteries in Examples 1, 2, 3, 4, 5, and Comparative Example 2 begins to decay after 40 cycles. Due to the presence of the lithium storage replenishment layer, the composite negative electrode in Examples 1-5 can maintain its capacity for approximately 30 more cycles after 50 cycles without decay. For Comparative Example 2, lacking a lithium storage replenishment layer, the capacity continuously decays after 40 cycles. The data shows that the lithium storage replenishment layer begins to function in the later stages of battery cycling, releasing and storing a certain amount of capacity, thus delaying the decay of battery capacity.

[0101] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this invention and their equivalents, this disclosure is also intended to include such modifications and variations.

Claims

1. An all-solid-state lithium metal battery, the all-solid-state lithium metal battery comprising: positive electrode; Solid electrolyte; and Negative electrode, wherein the negative electrode is a lithium composite negative electrode, comprising: Modified graphitized film material as a current collector; An active material layer is composited on the surface of the modified graphitized film, wherein the active material... The substrate is a continuous or intermittently distributed metallic lithium or lithium alloy foil; and A lithium storage replenishment layer is formed by the diffusion of lithium atoms into the modified graphitized film material, wherein the positive electrode, solid electrolyte and negative electrode are stacked or wrapped in sequence, and the active material layer of the negative electrode is in contact with the solid electrolyte.

2. The all-solid-state lithium metal battery according to claim 1, wherein the positive electrode active material in the positive electrode is selected from one or more of lithium iron phosphate, lithium-rich manganese-based materials, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, vanadium pentoxide, manganese dioxide, sulfur carbon, sulfurized polyacrylonitrile, iron disulfide and oxygen.

3. The all-solid-state lithium metal battery according to claim 1, wherein the solid electrolyte includes one or more of sulfide solid electrolyte, oxide solid electrolyte, halide solid electrolyte, and polymer solid electrolyte.

4. The all-solid-state lithium metal battery according to claim 1, wherein the all-solid-state lithium metal battery is a pouch battery, a cylindrical battery, or a steel-cased battery.

5. The all-solid-state lithium metal battery according to claim 1, wherein the modified graphitized film material comprises graphite or graphitized organic polymer and modifier and structural reinforcing agent, or is obtained by graphitization treatment of a film material made of graphene, modifier and structural reinforcing agent, wherein the modifier is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers, wherein the structural reinforcing agent is selected from at least one of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid, and wherein the organic polymer is selected from polyimide or polyacrylonitrile; The graphitization treatment is performed at a temperature of 2300-3000℃ for 0.5-2 hours. The modifier accounts for 0.1%-10% by mass, and the structural reinforcing agent accounts for 0.1%-10% by mass. The sheet resistance of the modified graphitized film is 0.1-100 mΩ / cm. 2 The membrane material has a thickness of 5-25 μm and a density of 1.3-2.0 g / cm³. 3 The tensile strength of the membrane material is 15-100MPa.

6. The all-solid-state lithium metal battery according to claim 1, wherein the thickness of the lithium storage replenishment layer is 0.5-25 μm; preferably greater than 2 μm, more preferably greater than 5 μm.

7. The all-solid-state lithium metal battery according to claim 1, wherein the thickness of the lithium metal or lithium alloy foil is 1-100 μm and the width is 50-1400 mm; The lithium alloy foil is a foil material formed by combining metallic lithium with any one or at least two elements selected from Ag, Au, Sn, Si, Zn, Al, Mg, In, Ga, B, Mn, Sb, Cr, C, V, Cu, Fe, or Ti.

8. A method for preparing an all-solid-state lithium metal battery according to any one of claims 1 to 7, the method comprising the following steps: Step 1: Preparation of lithium composite anode; Step 2: Preparation of the positive electrode: The positive electrode material is coated on the current collector using a dry or wet coating process to obtain the positive electrode layer; Step 3: Preparation of solid electrolyte membrane: The polymer solid electrolyte or inorganic solid electrolyte and lithium salt are formed into a membrane by a dry process, or the polymer solid electrolyte or inorganic solid electrolyte, lithium salt and solvent are formed into a membrane by a wet process. Step 4: The lithium composite anode, solid electrolyte membrane, and cathode are stacked or wound to form a battery cell, and the isostatic pressing process is used to make the layers in close contact.

9. The preparation method according to claim 8, wherein the lithium composite anode is prepared by the following steps: Step 1: Prepare the modified graphitized film material, and roll it up together with one side of the release film; Step 2: Unwind the lithium metal / lithium alloy foil and the modified graphitized film. Then, perform low-pressure bonding of the modified graphitized film with the side of the lithium metal / lithium alloy foil facing the side of the film without the release film attached. The pressure is set to 1-2 MPa. Remove the release film to obtain a single-sided lithium composite negative electrode. Step 3: Unwind another roll of lithium metal / lithium alloy foil, and pressure bond the side of the single-sided lithium composite anode without composite lithium to the unwound lithium metal / lithium alloy foil. The pressure is set to 3-5 MPa to obtain a preliminary double-sided lithium composite anode. Step 4: The preliminary double-sided lithium composite anode is rolled by hot rollers. The temperature of the hot rollers is 40-60℃ and the pressure is set to 1-2MPa to obtain the lithium composite anode.

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