A method for regenerating and repairing waste lithium cobalt oxide positive electrode material
Through the regeneration and repair method of supplementing lithium ions with co-doping of Mn, N, and S at high temperature, the problem of recycling and performance improvement of lithium cobalt oxide positive electrode materials for waste lithium ion batteries is solved, and efficient and low-cost electrode material regeneration and repair is achieved. The product shows excellent electrochemical performance under high pressure.
Patent Information
- Application Number
- CN202310225436.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-10
- Publication Date
- 2025-06-06
- Estimated Expiration
- 2043-03-10
AI Technical Summary
The prior art lacks low-cost and efficient recycling technology for lithium cobalt oxide cathode material for waste lithium-ion batteries, and regeneration and repair electrode materials are difficult to meet the standards for use of commercial electrode materials, especially at high voltages, with poor cycling stability.
High-performance lithium cobalt oxide cathode material (LCOMNS) was prepared by regeneration and repair methods of high temperature supplementation of lithium ions and co-doping of Mn, N, and S to restore layered structure and electrochemical properties, and inhibit harmful phase change during the release of lattice oxygen and deliquification.
The efficient regeneration and repair of waste lithium cobalt oxide cathode material is achieved. The obtained product has excellent discharge specific capacity and cycle stability under high pressure, and the preparation method is simple and economic benefits are high.
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Figure CN116364909B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of waste lithium-ion battery recycling, and in particular to a method for regenerating and repairing waste lithium cobalt oxide positive electrode materials. Background Art
[0002] Lithium-ion batteries have the advantages of high energy density, long life, high voltage, and low self-discharge rate, and are widely used in electrochemical energy storage devices for electronic devices and electric vehicles. In recent years, with the use of electronic products such as 3C products, smart wearables, and electric vehicles, the output of lithium cobalt oxide batteries has increased dramatically, and at the same time, a large amount of waste lithium cobalt oxide positive electrode materials and production waste from lithium ion batteries that need to be processed have been generated. Since waste lithium cobalt oxide positive electrode materials for lithium ion batteries contain a large amount of scarce metal resources such as cobalt and lithium, they can be used as a secondary source of metal elements. At the same time, its waste lithium ion battery components, such as toxic heavy metals and organic solvents, cause certain harm to the environment and human health. Therefore, considering the resource availability and environmental hazards of waste lithium ion batteries, it is of great significance to recycle waste lithium cobalt oxide positive electrode materials for lithium ion batteries.
[0003] At present, the main problem facing the recycling technology of waste lithium-ion batteries is the lack of low-cost and efficient recycling technology. Metal element extraction technology and non-destructive electrode material repair technology are the main recycling methods at present. Metal element extraction technology is to enrich, separate and recover the valuable metal elements in the positive electrode materials of waste lithium-ion batteries through methods such as hydrometallurgy, pyrometallurgy, biometallurgy, and mechanochemistry. However, it requires a relatively complex process flow, high energy consumption, and low economic benefits. In addition, secondary pollution such as waste slag and acidic wastewater is inevitably generated. Compared with the separation method for recovering metals from waste lithium-ion batteries, non-destructive electrode material repair technology is an effective recycling method. It can avoid the complex separation process, maximize the recovery of positive electrode materials, and realize the recycling of lithium-ion batteries. Effective and large-scale recycling of waste lithium-ion battery positive electrode materials is an urgent need to solve the environmental pollution and resource consumption caused by improper disposal. In addition, when lithium cobalt oxide is charged to a voltage higher than 4.3V, unstable phase changes such as anodic redox, oxygen escape, and side reactions with electrolytes will always occur, resulting in serious capacity decay. Whether the regenerated and repaired electrode materials can meet the use standards of commercial electrode materials is the primary issue facing the reuse of waste electrodes. Therefore, repairing and improving the performance of waste lithium-ion battery positive electrode materials and ensuring their cycle stability under high voltage are the challenges faced by regenerated and repaired electrodes. Summary of the invention
[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a regeneration and repair of waste lithium cobalt oxide positive electrode materials and their applications. The preparation method of the present invention is simple, and makes maximum use of waste lithium ion battery positive electrode materials. High-performance lithium cobalt oxide positive electrode materials (LCOMNS) are obtained by high-temperature lithium ion supplementation and Mn, N, and S co-doping and regeneration and repair. High-temperature lithium supplementation is beneficial to eliminate cracks and nano-impurity particles on the surface of waste electrode materials, directly repair the crystal structure of failed electrode materials, and restore the layered structure and electrochemical properties. The doping of Mn, N, and S inhibits the release of lattice oxygen and stabilizes the surface structure. Compared with commercial lithium cobalt oxide positive electrode materials, the regenerated and repaired LCOMNS has better electrochemical performance and cycle stability.
[0005] To achieve the above object, the present invention adopts the following technical solution: a method for regenerating and repairing waste lithium cobalt oxide positive electrode materials, comprising the following steps:
[0006] S1, adding manganese acetate and thiourea to an ethanol solution, stirring and mixing at a temperature of 50-100 ° C, and then adding waste lithium cobalt oxide powder and stirring to obtain a mixed solution, wherein the molar ratio of waste lithium cobalt oxide powder to manganese acetate and thiourea is (5-20): 0.18: 0.25, and the amount of the ethanol solution is 5-50mL / 10mmol waste lithium cobalt oxide powder; the mixed solution is evaporated and then dried to obtain a black powder;
[0007] S2. Mix the black powder and lithium carbonate in a molar ratio of 1:(0.1-0.5), grind them uniformly, and anneal them at 800-900° C. for 5-15 hours to obtain a high-performance lithium cobalt oxide positive electrode material, namely, LCOMNS material.
[0008] As a further improvement of the regeneration and repair method of waste lithium cobalt oxide positive electrode materials:
[0009] Preferably, the waste lithium cobalt oxide powder described in step S1 is collected from waste lithium cobalt oxide batteries, and the specific steps are as follows: dismantling and separating the waste lithium cobalt oxide batteries, calcining the disassembled positive electrode plates at a temperature of 400-600° C. for 1-2 hours to anneal, removing the binder and carbon black in the plates, and peeling off the waste lithium cobalt oxide powder from the aluminum foil.
[0010] Preferably, before disassembling and separating the used lithium cobalt oxide batteries, the used lithium cobalt oxide batteries are immersed in a 0.5-2 mol / L NaCl solution for complete discharge.
[0011] Preferably, in S1, the mixed solution is heated to 80-150° C. to evaporate the solvent, and then placed in an oven at 70-150° C. for drying.
[0012] Preferably, the molar ratio of the waste lithium cobalt oxide powder to manganese acetate and thiourea in step S1 is 10:0.18:0.25, and the amount of the ethanol solution is 25 mL / 10 mmol of the waste lithium cobalt oxide powder.
[0013] Preferably, in step S2, the annealing is performed by heating to 800-900° C. at a heating rate of 2-10° C. / min.
[0014] Preferably, the prepared LCOMNS material is used as a positive electrode material in a lithium-ion battery to carry out an electrochemical performance test.
[0015] Preferably, the steps of using the prepared LCOMNS material as a positive electrode material in a lithium-ion battery to conduct an electrochemical performance test are as follows:
[0016] Weigh LCOMNS material, polyvinylidene fluoride binder and SuperP conductive agent in a mass ratio of 8:1:1, add them into N-methylpyrrolidone in turn and mix to obtain a black slurry with a solid content of 40%;
[0017] The black slurry is coated on aluminum foil and vacuum dried at 70-120°C for 5-15 hours. The solid content on the coated aluminum foil after drying is 1.5-2 mg / cm 2 The dried coated aluminum foil was punched into a 14 mm disc as the positive electrode, the lithium sheet was used as the negative electrode, Celgard2500 was used as the separator between the positive and negative electrodes, and 1.0MLiPF 6 As the electrolyte, it was assembled into CR2025 button cells for electrochemical performance testing.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] 1) The present invention provides a method for regenerating and repairing waste lithium cobalt oxide positive electrode materials, wherein the collected waste lithium cobalt oxide powder is evenly mixed with manganese acetate and thiourea, and then an appropriate amount of Li 2 CO 3 The LCOMNS material doped with Mn, N and S is obtained by grinding fully and annealing. The LCOMNS material doped with Li and Mn, N and S is restored from the high temperature. The layered structure of the waste lithium cobalt oxide is restored. The co-doping of the three ions of Mn, N and S inhibits the release of lattice oxygen and harmful phase changes during the delithiation process, and stabilizes the surface structure. The electrochemical performance test is carried out by loading into a button battery. In the voltage range of 3.0-4.5V, it has a high discharge specific capacity and cycle stability. This strategy provides an effective method for directly converting waste batteries into high energy density batteries. Therefore, the present invention can not only maximize the use of the positive electrode material of waste lithium cobalt oxide batteries, but also has a simple preparation method, and the obtained product has excellent electrochemical performance under high pressure.
[0020] Among them, in order to ensure the safe disassembly of the battery, the used lithium cobalt oxide battery is immersed in NaCl solution for complete discharge, and then the battery is disassembled and separated. The used lithium cobalt oxide positive electrode is calcined to remove the binder and carbon black in the electrode, the aluminum foil remains intact, and the powder is easier to peel off from the aluminum foil.
[0021] The LCOMNS material, a product of doping waste lithium cobalt oxide positive electrode materials with Mn, N, and S, was mixed with polyvinylidene fluoride binder, SuperP conductive agent and appropriate amount of N-methylpyrrolidone to obtain a black slurry, which was coated on aluminum foil, dried, and stamped as the positive electrode. The lithium sheet was used as the negative electrode, Celgard2500 was used as the separator between the positive and negative electrodes, and 1.0MLiPF 6 As an electrolyte, it is used to assemble CR2025 button cells. The electrochemical properties of the active materials were tested on the CHI760E electrochemical workstation and LAND test system. Under room temperature conditions, the electrochemical performance was evaluated by testing cyclic voltammetry (CV), cycle performance and rate performance, which confirmed that the regeneration and repair product LCOMNS of the waste lithium-ion battery lithium cobalt oxide positive electrode material doped with Mn, N, and S provided by the present invention can inhibit the escape of lattice oxygen and harmful phase changes under high pressure, and has excellent discharge specific capacity and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.
[0023] Figure 1 The electron microscope images of the LCOMNS material prepared in Example 1 of the present invention, wherein (a)-(b) are scanning electron microscope images at different magnifications, and (c)-(d) are transmission electron microscope images at different magnifications.
[0024] Figure 2 This is the X-ray diffraction pattern of the LCOMNS material prepared in Example 1 of the present invention.
[0025] Figure 3 This is a cyclic voltammetry curve of the LCOMNS material prepared in Example 1 of the present invention.
[0026] Figure 4 (a) is a first cycle charge-discharge curve diagram of the LCOMNS material prepared in Example 1 of the present invention at 0.2C, and (b) is a charge-discharge curve diagram of different cycles at 0.5C.
[0027] Figure 5 This is a cycle performance diagram of the LCOMNS material prepared in Example 1 of the present invention.
[0028] Figure 6 This is a rate performance diagram of the LCOMNS material prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.
[0030] Example 1
[0031] This embodiment provides a regeneration and repair of waste lithium cobalt oxide positive electrode materials, which specifically includes the following steps:
[0032] Step S1, immersing the waste lithium cobalt oxide battery in a 1 mol NaCl solution to completely discharge it, then disassembling and separating the battery, recovering the positive electrode sheet of the waste lithium cobalt oxide battery, calcining it at 500° C. for 2 hours, and peeling off and collecting the waste lithium cobalt oxide powder from the aluminum foil;
[0033] Step S2, 0.031 g of manganese acetate, 0.019 g of thiourea and 25 mL of ethanol solution were uniformly mixed, fully stirred at a temperature of 70° C. for 1 hour, and then 1 g of waste lithium cobalt oxide powder was added and stirred for 1 hour to obtain a mixed solution; wherein the molar ratio of waste lithium cobalt oxide powder to manganese acetate and thiourea was 10:0.18:0.25;
[0034] The temperature of the mixed solution was raised to 100°C, and the temperature was maintained to evaporate the solution, and the solid was collected and dried in an oven at 120°C to obtain a black powder;
[0035] Step S3, mixing the above black powder and lithium carbonate in a molar ratio of 1:0.15, grinding evenly, heating to 850° C. at a heating rate of 5° C. / min and annealing for 10 hours to obtain a high-performance lithium cobalt oxide positive electrode material, namely, LCOMNS material 1.
[0036] The LCOMNS material regenerated and repaired from the waste lithium cobalt oxide positive electrode material prepared in Example 1 of the present invention was subjected to microstructure observation, component analysis and electrochemical performance testing, thereby obtaining the following experimental results:
[0037] (1) The LCOMNS material prepared in Example 1 of the present invention was observed and photographed using a scanning electron microscope and a high-power transmission microscope, and the following Figure 1The scanning electron microscope images and high-magnification transmission electron microscope images shown; among them, Figure 1 (a) and 1(b) are scanning electron microscope images of the LCOMNS material prepared in Example 1 of the present invention at different resolutions; Figure 1 (c) and Figure 1 (d) is a high-magnification transmission electron microscope image of the LCOMNS material prepared in Example 1 of the present invention at different resolutions. Figure 1 (a) and Figure 1 (b) It can be seen that the LCOMNS material prepared in Example 1 of the present invention is uniformly covered with a layer of rough and uniform small particles on a relatively smooth surface; Figure 1 (c) and Figure 1 (d) It can be seen that the surface of the LCOMNS material prepared in Example 1 of the present invention has small particles distributed on it, which corresponds to the results of the scanning electron microscope image. The small particles on the surface of LCOMNS clearly have a lattice fringe spacing of 0.164nm, which is related to the (114) surface of lithium sulfate. The results show that high-valent S is doped into LCOMNS to form SO 4 2- Polyanions.
[0038] (2) The components of LCOMNS prepared by X-ray diffractometer and regenerated from the waste lithium cobalt oxide battery positive electrode material prepared in Example 1 of the present invention were analyzed, and the following were obtained: Figure 2 The X-ray diffraction pattern shown; wherein, Figure 2 The horizontal axis is represented by 2θ (i.e., diffraction angle), and the vertical axis is represented by intensity. Figure 2 It can be seen that the diffraction peaks of the product finally prepared in Example 1 of the present invention at 18.9°, 37.4°, 38.4°, 39.1°, 45.2°, 46.4°, 49.4°, 59.6°, 65.4°, 66.4° and 69.7° can all be compared with the diffraction peaks of LiCoO 2 The (003), (101), (006), (012), (104), (015), (107), (018), (110) and (113) crystal planes of (JCPDS.50-0653) correspond to each other, indicating that the LiCoO 2 The main structure of.
[0039] (3) The steps of testing the electrochemical performance of LCOMNS material 1 as a positive electrode material in a lithium-ion battery are as follows: weigh LCOMNS material 1, polyvinylidene fluoride binder and SuperP conductive agent in a mass ratio of 8:1:1, add them to N-methylpyrrolidone and mix them to obtain a black slurry with a solid content of 100 mg; apply the black slurry on aluminum foil and vacuum dry it at 110°C for 10 hours. After drying, the content of solid matter on the coated aluminum foil is 1.5 mg / cm 2 On the LAND test system, the dried coated aluminum foil was punched into 14 mm discs as the positive electrode, the lithium sheet was used as the negative electrode, Celgard2500 was used as the separator between the positive and negative electrodes, and 1.0MLiPF 6 As the electrolyte, CR2025 button cells were assembled for electrochemical performance testing.
[0040] The assembled CR2025 button cell was electrochemically tested using cyclic voltammetry (scan rate of 0.1 mV / s) on a CHI760E electrochemical workstation. Figure 3 The cyclic voltammetry curves are shown. The main anodic / cathodic peaks of LCOMNS at 4.04 / 3.86 V are Co 3+ / Co 4+ For the reversible transformation that occurred, two pairs of weak peaks were observed at 4.11 / 4.06V and 4.18 / 4.14V, which is due to the reversible transformation of LCO from hexagonal (H1) to monoclinic (M). The regenerated and repaired LCOMNS has a higher redox peak, indicating that its charge transfer kinetics is faster. The voltage difference between the anode and cathode peaks of LCOMNS is smaller, indicating that the doping of Mn, N, and S accelerates the diffusion kinetics of lithium ions on the cathode surface. Due to the synergistic effect of doping, the Li + The diffusion barrier weakens the polarization during the charge and discharge process and inhibits electrode oxidation.
[0041] The assembled CR2025 button battery was charged and discharged in the LAND test system, and the results were as follows: Figure 4 The charge and discharge curves are shown in Figure 1. Figure 4 (a) is the first cycle charge and discharge curve of LCOMNS prepared in Example 1 of the present invention at 0.2C, Figure 4 (b) is a charge and discharge curve of LCOMNS prepared in Example 1 of the present invention at different cycles at 0.5C. Figure 4 (a) and Figure 4 (b) It can be seen that the initial discharge capacity of the LCOMNS regenerated and repaired by doping Mn, N, and S with the waste cobalt oxide lithium battery positive electrode material prepared in Example 1 of the present invention in the first cycle within the voltage range of 3.0 to 4.5 V at 0.2C is 213.7 mAh / g; at 0.5C, as the number of charge and discharge cycles increases, the discharge capacity decays slightly.
[0042] The assembled CR2025 button battery was tested for cycle performance in the LAND test system, and the results were as follows: Figure 5 The cycling performance results of LCOMNS at 0.5C are shown in Figure 2. Figure 5 It can be seen that within the voltage range of 3.0-4.5V, after 100 cycles, the discharge specific capacity still remains at 192.6mAh / g, and the capacity retention rate is 92.5%. The regenerated and repaired LCOMNS material has stable cycle performance.
[0043] The assembled CR2025 button battery was tested on the LAND test system for rate performance, and the results were as follows: Figure 6 The rate performance of LCOMNS at 0.1C, 0.2C, 0.5C, 1C, 2C, 3C and 5C is shown. Figure 6 It can be seen that: in the voltage range of 3.0-4.5V, the discharge specific capacity of LCOMNS is 210.7, 211, 205.7, 197.4, 185.1176.1 and 162.2mAh / g respectively. The regenerated and repaired LCOMNS material can still maintain a high discharge specific capacity at high rate.
[0044] Example 2
[0045] This embodiment provides a regeneration and repair of waste lithium cobalt oxide positive electrode materials. The specific steps are referred to Example 1, except that manganese acetate is not added in step S2, and finally a lithium cobalt oxide positive electrode material, namely, LCONS material 2, is obtained.
[0046] Referring to the method of assembling CR2025 button cells using LCOMNS material 1 prepared in Example 1, LCONS material 2 was used to assemble CR2025 button cells for electrochemical performance testing, and the results were as follows: within the voltage range of 3.0-4.5V, at 0.1C, 0.2C, 0.5C, 1C, 2C, 3C and 5C rates, the discharge specific capacities of LCONS were 191.1, 189, 184.4, 177.8, 167.8, 160.7 and 149.8 mAh / g, respectively. At different rates, the discharge specific capacities of LCONS material 2 were all lower than those of LCOMNS material 1.
[0047] Example 3
[0048] This embodiment provides a regeneration and repair of waste lithium cobalt oxide positive electrode materials. The specific steps refer to those of Example 1, except that in step S2, thiourea is not added, and only manganese acetate is added to achieve single element Mn doping, and finally a lithium cobalt oxide positive electrode material, namely, LCOM material 3, is obtained.
[0049] Referring to the method of assembling CR2025 button cells using LCOMNS material 1 prepared in Example 1, LCOM material 3 was used to assemble CR2025 button cells for electrochemical performance testing, and the results were as follows: within the voltage range of 3.0-4.5V and at 0.1C, 0.2C, 0.5C, 1C, 2C, 3C and 5C rates, the discharge specific capacities of LCOM were 198.4, 187.9, 179.4, 170, 154.2, 141.0 and 119.7 mAh / g, respectively. Compared with LCOMNS material 1, the discharge specific capacities of LCOM material 3 at different rates were lower.
[0050] In summary, the embodiments of the present invention can not only recycle the positive electrode materials of waste lithium cobalt oxide batteries to the maximum extent, but also have a simple preparation method. The effective doping of Mn, N, and S inhibits the escape of lattice oxygen and stabilizes the surface structure. The obtained product LCOMNS has excellent discharge specific capacity and cycle stability under high voltage.
[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A method for regenerating and repairing waste lithium cobalt oxide positive electrode materials, It is characterized in that The steps include: S1, adding manganese acetate and thiourea to an ethanol solution, stirring and mixing at a temperature of 50-100 ° C, and then adding waste lithium cobalt oxide powder and stirring to obtain a mixed solution, wherein the molar ratio of waste lithium cobalt oxide powder to manganese acetate and thiourea is (5-20): 0.18: 0.25, and the amount of the ethanol solution is 5-50mL / 10mmol waste lithium cobalt oxide powder; the mixed solution is evaporated and then dried to obtain a black powder; S2. Mix the black powder and lithium carbonate in a molar ratio of 1:(0.1-0.5), grind them uniformly, and anneal them at 800-900° C. for 5-15 hours to obtain a high-performance lithium cobalt oxide positive electrode material, namely, LCOMNS material.
2. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 1, It is characterized in that The waste lithium cobalt oxide powder described in step S1 is collected from waste lithium cobalt oxide batteries, and the specific steps are as follows: dismantling and separating the waste lithium cobalt oxide batteries, calcining the disassembled positive electrode plates at a temperature of 400-600° C. for 1-2 hours to anneal, removing the binder and carbon black in the plates, and peeling off the waste lithium cobalt oxide powder from the aluminum foil.
3. The regeneration and repair method of waste lithium cobalt oxide positive electrode material according to claim 2, It is characterized in that Before disassembling and separating the spent lithium cobalt oxide batteries, the spent lithium cobalt oxide batteries are immersed in a 0.5-2 mol / L NaCl solution for complete discharge.
4. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 1, It is characterized in that In step S1, the mixed solution is heated to 80-150° C. to evaporate the solvent, and then placed in an oven at 70-150° C. for drying.
5. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 1, It is characterized in that The molar ratio of the waste lithium cobalt oxide powder to manganese acetate and thiourea in step S1 is 10:0.18:0.25, and the amount of the ethanol solution is 25 mL / 10 mmol of the waste lithium cobalt oxide powder.
6. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 1, It is characterized in that In step S2, the material is heated to 800-900° C. at a heating rate of 2-10° C. / min for annealing.
7. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 1, It is characterized in that The prepared LCOMNS material was used as the positive electrode material in lithium-ion batteries for electrochemical performance testing.
8. The method for regenerating and repairing waste lithium cobalt oxide positive electrode materials according to claim 7, It is characterized in that The steps for testing the electrochemical performance of the prepared LCOMNS material as a cathode material in a lithium-ion battery are as follows: Weigh LCOMNS material, polyvinylidene fluoride binder and SuperP conductive agent in a mass ratio of 8:1:1, add them into N-methylpyrrolidone in turn and mix to obtain a black slurry with a solid content of 40%; The black slurry is coated on aluminum foil and vacuum dried at 70-120°C for 5-15 hours. The solid content on the coated aluminum foil after drying is 1.5-2 mg / cm 2 The dried coated aluminum foil was punched into a 14 mm disc as the positive electrode, the lithium sheet was used as the negative electrode, Celgard 2500 was used as the separator between the positive and negative electrodes, and 1.0 M LiPF 6 As the electrolyte, it was assembled into CR2025 button cells for electrochemical performance testing.