A method for producing spherical cobalt tetroxide with a multilayer structure

Abstract

The present invention relates to a method for producing multilayer spherical cobalt tetroxide, belonging to the field of battery manufacturing technology. This method utilizes an innovative process combining doping enhancement, gradient pore design, and carbon composites to effectively address the problem of multilayer spherical hollow cobalt tetroxide easily collapsing during high-temperature calcination and battery charge-discharge cycles. The resulting multilayer spherical cobalt tetroxide combines high specific surface area with high stability, significantly improving the charge-discharge efficiency and cycle life of lithium-ion batteries.

Description

Technical Field

[0001] The invention belongs to the technical field of battery production and manufacturing, and relates to a production method of spherical cobalt tetroxide with a multi-layer structure. Background Art

[0002] With the rapid development of the lithium-ion battery industry, the performance of cathode materials has become a key factor in determining the overall performance of batteries. As a highly promising precursor for lithium-ion battery cathode materials, cobalt tetroxide (Co3O4) has attracted considerable attention for its performance, with the specific surface area being a particularly crucial factor.

[0003] Specific surface area is directly related to the electrochemical activity of a material. Cobalt tetroxide, with its large surface area, can create more active sites for electrochemical reactions, significantly improving battery charge and discharge performance and cycle stability. During the battery's charge and discharge process, the high surface area of ​​cobalt tetroxide facilitates smoother insertion and extraction of lithium ions, effectively accelerating the reaction rate and improving charge and discharge efficiency. It also reduces electrode polarization, significantly extending the battery's cycle life.

[0004] Therefore, developing a production method to increase the specific surface area of ​​cobalt tetroxide has important practical significance and market demand. Summary of the Invention

[0005] The object of the present invention is to provide a method for producing multi-layer spherical cobalt oxide. The prepared multi-layer spherical cobalt oxide has both high specific surface area and high stability.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for producing multi-layer spherical cobalt oxide comprises the following steps:

[0008] S1. Adding a soluble cobalt salt and a precipitant to deionized water and stirring to obtain a mixed solution 1;

[0009] S2, adding a morphology directing agent to the mixed solution 1, stirring, and ultrasonically treating to obtain a mixed solution 2;

[0010] S3, the mixed solution 2 is placed in a reactor, the pH of the mixed solution 2 is adjusted to 9-11 in stages, and the mixture is reacted at 60-80° C. for 3-5 hours to generate a hollow spherical precursor. After the reaction is completed, the precursor is washed, centrifuged, and dried;

[0011] S4. calcining the treated precursor in stages: in the first stage, heating the temperature to 300-400° C. at a heating rate of 2-5° C. / min and keeping the temperature for 1-2 hours; in the second stage, heating the temperature to 500-600° C. at a heating rate of 5-8° C. / min and keeping the temperature for 2-3 hours to form spherical cobalt trioxide with a multilayer structure.

[0012] Furthermore, a dopant is added to the mixed solution 1 in step S2. The dopant is manganese nitrate, and the doping amount of the manganese nitrate is 0.5-5% of the molar amount of the cobalt salt.

[0013] Preferably, the morphology directing agent comprises citric acid and sodium lauryl sulfate, the molar ratio of the citric acid to the cobalt salt is 1:(1-2), and the mass ratio of the citric acid to sodium lauryl sulfate is 1:(0.1-0.5).

[0014] Furthermore, in step S3, the pH value of the mixed solution 2 is adjusted in stages:

[0015] a. In the first stage, the pH of the mixed solution 2 is adjusted to 8-9, and the mixture is reacted in a reactor at 60-70°C for 1-2 hours to form a dense core layer;

[0016] b. In the second stage, the pH of the mixed solution 2 is adjusted to 10-11, and the mixture is reacted in a reactor at 70-80°C for 2-3 hours to generate a porous shell layer, thereby forming a core-shell gradient pore structure.

[0017] Preferably, during the calcination process in step S4, a mixed gas of nitrogen and air is introduced, and the volume of the nitrogen accounts for 10-30% of the volume of the mixed gas.

[0018] Furthermore, after the calcination in step S4, the following steps are further included:

[0019] Carbon source composite treatment: The calcined product is mixed with a carbon source and calcined at 700-800°C for 1-2 hours to form a carbon coating layer.

[0020] Preferably, the carbon source is one of glucose, polyvinyl pyrrolidone or graphene, and the mass ratio of the carbon source to the calcined product is (0.1-0.3):1.

[0021] Preferably, the precipitant in step S1 is one of sodium hydroxide, sodium carbonate or ammonia water, and the molar ratio of the precipitant to the cobalt salt is (2-4):1.

[0022] Beneficial effects of the present invention:

[0023] (1) The multi-layered spherical hollow structure of cobalt tetroxide produced by the present invention effectively solves the specific surface area problem mentioned in the background technology. The hollow spherical structure of cobalt tetroxide forms a larger space inside, and the multi-layer structure increases the surface level of the material. The combination of the two significantly increases the specific surface area of ​​cobalt tetroxide. The larger specific surface area provides more active sites for electrochemical reactions, which helps lithium ions to be embedded and extracted more smoothly, thereby improving the charge and discharge performance and cycle stability of the battery.

[0024] (2) Through the synergistic effect of doping enhancement, gradient pore design and carbon composite process, the problem of easy collapse of cobalt tetroxide in multi-layer spherical hollow structure during high temperature calcination and battery charge and discharge cycle is effectively solved. First, in the early stage of structure formation, step S3 forms a dense core layer in the first stage by adjusting the pH value in stages. This core layer serves as the basis of the entire structure, providing a solid support for cobalt tetroxide and greatly enhancing the ability of the structure to resist deformation. Secondly, the dopant is added. In step S2, the dopant (manganese nitrate) will be evenly dispersed in the core layer and shell layer. The ions in the dopant enter the lattice of cobalt tetroxide, optimize the overall crystal structure, enhance the interaction force between atoms, and comprehensively improve the intrinsic stability of cobalt tetroxide. Finally, the carbon source composite treatment in step S4 puts a layer of "armor" on the material, and the formed carbon coating layer is wrapped around the outermost layer of the cobalt tetroxide particles. It not only improves the conductivity of the material, but also gives the structure a certain flexibility and mechanical strength. When stress is generated during high-temperature calcination or battery charge-discharge cycling, the carbon coating effectively buffers the effects of external stress on the internal structure, protecting the core-shell structure. Throughout the entire preparation process, each process step works in tandem to enhance the material's structural stability at various levels. From the dense inner core layer, to the uniformly doped and reinforced overall structure, to the outer carbon coating, these three elements work together from the inside out to create a solid defense for the multi-layered spherical hollow structure of cobalt oxide, providing it with enhanced structural stability.

[0025] (3) The high specific surface area and stable structure make the transmission of lithium ions during the battery charging and discharging process more efficient, accelerate the reaction rate, and improve the charging and discharging efficiency. At the same time, the stable structure effectively reduces the electrode polarization phenomenon, greatly extending the cycle life of the battery. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0027] Example 1

[0028] A method for producing multi-layer spherical cobalt oxide comprises the following steps:

[0029] S1: Preparation of mixed solution 1

[0030] In a 500 mL three-necked flask, 200 mL of deionized water was added, and then 200 mL of 1 mol / L cobalt nitrate solution (Co(NO3)2·6H2O, 1 mol / L) was taken and added to the deionized water in the three-necked flask. Then, according to the molar ratio of cobalt salt to precipitant being 1:2, 5.6 mol / L ammonia water (precipitant) was added dropwise to the three-necked flask. At the same time, a mechanical stirrer was turned on and stirred at 300 rpm for 30 minutes to obtain a mixed solution 1.

[0031] S2: Preparation of mixed solution 2

[0032] A morphology-directing agent and a dopant, specifically citric acid and sodium lauryl sulfate, were added to mixed solution 1. Citric acid was added to mixed solution 1 at a molar ratio of cobalt salt to citric acid of 1.5:1. Sodium lauryl sulfate was also added to mixed solution 1 at a mass ratio of citric acid to sodium lauryl sulfate of 1:0.1. Manganese nitrate, a dopant, was weighed to 0.5% of the molar amount of cobalt salt and added to mixed solution 1. The mixture was then stirred to thoroughly mix the ingredients. The mixture was then transferred to an ultrasonic device and sonicated at 40 kHz for 30 minutes to produce mixed solution 2.

[0033] S3: Generation of hollow spherical precursors and post-processing

[0034] a. The first stage: the mixed solution 2 was transferred to a reactor, and the pH of the mixed solution 2 was adjusted to 8, and the reaction was carried out at 60 ° C for 2 hours to generate a hollow spherical precursor;

[0035] b. In the second stage, the pH was adjusted to 10, the reactor temperature was raised to 70°C, and the reaction was continued for 3 hours to generate a porous shell layer, thereby forming a core-shell gradient pore structure;

[0036] c. After the conditioning reaction is complete, transfer the product from the reactor to a centrifuge tube and centrifuge at an appropriate speed. Wash the precipitate with deionized water. Repeat the centrifugation and washing process three times. Place the washed precipitate in a vacuum drying oven at 80°C for 12 hours.

[0037] S4: Calcination and carbon source composite treatment

[0038] The treated precursor is calcined in stages:

[0039] The first stage of calcination: the precursor is placed in a high-temperature calcination furnace, and a mixture of nitrogen and air (nitrogen accounts for 10% by volume, that is, the volume ratio of nitrogen to air is 1:9) is introduced. The furnace temperature is raised to 300°C at a heating rate of 2°C / min and kept at this temperature for 2 hours.

[0040] Second stage calcination: After the first stage calcination, the furnace temperature was raised to 500°C at a heating rate of 5°C / min and kept at this temperature for 3 hours to form a multilayer spherical cobalt oxide;

[0041] Finally, a carbon source was added to the sample: glucose was used in a ball mill at a mass ratio of calcined product to carbon source of 1:0.1. The calcined product and glucose were ball-milled for 40 minutes. The mixed sample was then calcined in an argon atmosphere at 700°C for 2 hours to form a carbon coating.

[0042] Example 2

[0043] A method for producing multi-layer spherical cobalt oxide comprises the following steps:

[0044] S1: Preparation of mixed solution 1

[0045] In a 500 mL three-necked flask, 200 mL of deionized water was added, and then 200 mL of 1 mol / L cobalt nitrate solution (Co(NO3)2·6H2O, 1 mol / L) was taken and added to the deionized water in the three-necked flask. Then, 8.1 mol / L ammonia water (precipitant) was added dropwise to the three-necked flask according to the molar ratio of cobalt salt to precipitant of 1:3. At the same time, a mechanical stirrer was turned on and stirred at 300 rpm for 30 minutes to obtain a mixed solution 1.

[0046] S2: Preparation of mixed solution 2

[0047] A morphology-directing agent and a dopant, specifically citric acid and sodium lauryl sulfate, were added to mixed solution 1. Citric acid was added to mixed solution 1 at a molar ratio of cobalt salt to citric acid of 1.5:1. Sodium lauryl sulfate was also added to mixed solution 1 at a mass ratio of citric acid to sodium lauryl sulfate of 1:0.3. Manganese nitrate, a dopant, was weighed at 3% of the molar amount of cobalt salt and added to mixed solution 1. The mixture was then stirred thoroughly to mix the ingredients. The mixture was then transferred to an ultrasonic device and sonicated at 40 kHz for 30 minutes to produce mixed solution 2.

[0048] S3: Generation of hollow spherical precursors and post-processing

[0049] a. The first stage: the mixed solution 2 was transferred to a reactor, and the pH of the mixed solution 2 was adjusted to 8.5, and the reaction was carried out at 65 ° C for 1.5 hours to generate a hollow spherical precursor;

[0050] b. In the second stage, the pH was adjusted to 10.5, the reactor temperature was raised to 75°C, and the reaction was continued for 2.5 hours to generate a porous shell layer, thereby forming a core-shell gradient pore structure;

[0051] c. After the conditioning reaction is complete, transfer the product from the reactor to a centrifuge tube and centrifuge at an appropriate speed. Wash the precipitate with deionized water. Repeat the centrifugation and washing process three times. Place the washed precipitate in a vacuum drying oven at 80°C for 12 hours.

[0052] S4: Calcination and carbon source composite treatment

[0053] The treated precursor is calcined in stages:

[0054] The first stage of calcination: the precursor is placed in a high-temperature calcination furnace, and a mixture of nitrogen and air (nitrogen accounts for 20% by volume, that is, the volume ratio of nitrogen to air is 2:8) is introduced. The furnace temperature is raised to 350°C at a heating rate of 3.5°C / min and kept at this temperature for 1.5 hours.

[0055] Second stage calcination: After the first stage calcination, the furnace temperature was raised to 550°C at a heating rate of 6.5°C / min and kept at this temperature for 2.5 hours to form a multi-layered spherical cobalt oxide.

[0056] Carbon source composite treatment: The calcined product and glucose were ball milled in a ratio of 1:0.2 (mass ratio). The mixed sample was then calcined in an argon atmosphere at 750°C for 1.5 hours to form a carbon coating.

[0057] Example 3

[0058] A method for producing multi-layer spherical cobalt oxide comprises the following steps:

[0059] S1: Preparation of mixed solution 1

[0060] In a 500 mL three-necked flask, 200 mL of deionized water was added, and then 200 mL of 1 mol / L cobalt nitrate solution (Co(NO3)2·6H2O, 1 mol / L) was taken and added to the deionized water in the three-necked flask. Then, 10.7 mol / L ammonia water (precipitant) was added dropwise to the three-necked flask according to the molar ratio of cobalt salt to precipitant of 1:4. At the same time, a mechanical stirrer was turned on and stirred at 300 rpm for 30 minutes to obtain a mixed solution 1.

[0061] S2: Preparation of mixed solution 2

[0062] A morphology-directing agent and a dopant, specifically citric acid and sodium lauryl sulfate, were added to mixed solution 1. Citric acid was added to mixed solution 1 at a molar ratio of cobalt salt to citric acid of 2:1. Sodium lauryl sulfate was also added to mixed solution 1 at a mass ratio of citric acid to sodium lauryl sulfate of 1:0.5. Manganese nitrate, a dopant, was weighed at 5% of the molar amount of cobalt salt and added to mixed solution 1. The mixture was then stirred to thoroughly mix the ingredients. The mixture was then transferred to an ultrasonic device and sonicated at 40 kHz for 30 minutes to produce mixed solution 2.

[0063] S3: Generation of hollow spherical precursors and post-processing

[0064] a. The first stage: the mixed solution 2 was transferred to a reactor, and the pH of the mixed solution 2 was adjusted to 9, and the reaction was carried out at 70 ° C for 1 hour to generate a hollow spherical precursor;

[0065] b. In the second stage, the pH was adjusted to 11, the reactor temperature was raised to 80°C, and the reaction was continued for 2 hours to generate a porous shell layer, thereby forming a core-shell gradient pore structure;

[0066] c. After the conditioning reaction is complete, transfer the product from the reactor to a centrifuge tube and centrifuge at an appropriate speed. Wash the precipitate with deionized water. Repeat the centrifugation and washing process three times. Place the washed precipitate in a vacuum drying oven at 80°C for 12 hours.

[0067] S4: Calcination and carbon source composite treatment

[0068] The treated precursor is calcined in stages:

[0069] The first stage of calcination: the precursor is placed in a high-temperature calcination furnace, and a mixture of nitrogen and air (nitrogen accounts for 30% by volume, that is, the volume ratio of nitrogen to air is 3:7) is introduced. The furnace temperature is raised to 400°C at a heating rate of 5°C / min and kept at this temperature for 1 hour.

[0070] Second stage calcination: After the first stage calcination, the furnace temperature was raised to 600°C at a heating rate of 8°C / min and kept at this temperature for 2 hours to form a multi-layered spherical cobalt oxide.

[0071] Carbon source composite treatment: Glucose was used as the carbon source in a calcined product:carbon source mass ratio of 1:0.3. The calcined product and glucose were ball milled for 40 minutes. The mixed sample was then calcined in an argon atmosphere at 800°C for 1 hour to form a carbon coating.

[0072] Comparative Example 1

[0073] The difference from Example 2 is that: in step S3, the staged pH control is cancelled, the pH of the mixed solution 2 is adjusted to 10.5, and then the mixed solution 2 is transferred to a reactor and reacted at 75° C. for 4 hours.

[0074] Comparative Example 2

[0075] The difference from Example 2 is that manganese nitrate is not added in step S2.

[0076] Comparative Example 3

[0077] The difference from Example 2 is that the carbon composite treatment in step S4 is omitted.

[0078] Test Case

[0079] The finished products of the multilayer spherical cobalt trioxide prepared in Example 2 and Comparative Examples 1-3 were used as samples to conduct the following tests:

[0080] (1) Specific surface area test (BET nitrogen adsorption method): 50 mg of sample was placed in a Quantachrome Autosorb-iQ instrument and vacuum degassed at 200°C for 6 hours. Nitrogen adsorption-desorption was then performed at liquid nitrogen temperature (77K). The specific surface area was calculated using the BET model. A larger specific surface area indicates a greater number of electrochemically active sites.

[0081] (2) Tap density test: 5 g of sample was placed in a 25 mL graduated cylinder and vibrated at 250 times per minute using a Hosokawa PT-S tap density meter. The density (g / cm2) was recorded when the sample was tapped to a constant volume. 3 ).

[0082] (3) Cycle retention test (500 cycles):

[0083] Battery Assembly: Sample, acetylene black, and PVDF were slurried in an 80:10:10 ratio, coated onto aluminum foil, and vacuum-dried at 120°C for 12 hours. Coin cells (CR2032) were assembled in a glove box using metallic lithium as the counter electrode and a 1M LiPF6 / EC:DMC (1:1) electrolyte.

[0084] Test conditions: 0.5C (1C=137 mA / g), voltage window 3.0-4.3 V, record the 1st and 500th discharge capacities, and calculate the retention rate (%).

[0085] (4) Mechanical strength test: 1g of sample was placed in a mold and subjected to a pressure of 10 MPa for 5 minutes. After removal, the sample was passed through a 325 mesh sieve (45 μm) and the mass percentage of unbroken particles was calculated. The lower the crushing rate, the higher the mechanical strength of the material and the better the electrode processing performance.

[0086] The test data of the above four test cases are shown in Table 1.

[0087] Table 1:

[0088]

[0089] As can be seen from Table 1:

[0090] (1) The specific surface area of ​​Example 2 reaches 82.5m 2 / g, while Comparative Example 1 is only 45.6m 2 / g. Comparative Example 1 eliminated the staged pH control, which prevented the formation of a core-shell gradient pore structure and significantly affected the specific surface area. In contrast, the present invention achieves a multi-layered spherical hollow structure by adjusting the pH value in stages to form a dense core layer and a porous shell layer. This structure has a large internal space and rich surface layers, effectively increasing the specific surface area and providing more active sites for electrochemical reactions.

[0091] (2) The tap density of Example 2 is 2.02 g / cm 3 , higher than 1.68g / cm2 of Comparative Example 1 3 , 1.78g / cm2 of Comparative Example 2 3 and 1.95 g / cm2 of Comparative Example 3 3 Comparative Example 1 lacks staged pH regulation, which prevents the formation of a reasonable core-shell gradient pore structure. The internal structure is loose, resulting in a low tap density. Comparative Example 2 does not add manganese nitrate for doping and strengthening, and the overall structure is not compact enough. Comparative Example 3 does not undergo carbon composite treatment, and the structural strength and density of the material are slightly inferior. This shows that the dense core layer and gradient pore structure formed by staged pH adjustment, combined with doping and carbon composite processes, can effectively improve the tap density of the material and optimize the internal structure of the material.

[0092] (3) The cycle retention rate of Example 2 is 94.7%, which is much higher than 72.1% of Comparative Example 1, 85.2% of Comparative Example 2, and 82.6% of Comparative Example 3. Comparative Example 1 cancels the staged pH control, resulting in poor structural stability. The structure is prone to collapse during the charge and discharge cycle, resulting in obstructed lithium ion transmission and low cycle retention rate; Comparative Example 2 lacks doping strengthening, and the crystal structure is not stable enough, which affects the charge and discharge performance; Comparative Example 3 does not undergo carbon composite treatment, and cannot effectively buffer external stress, thereby reducing the cycle life of the battery. This shows that the present invention enhances the structural stability of the material and reduces the electrode polarization phenomenon through the synergy of multiple processes, thereby significantly improving the cycle retention rate of the battery.

[0093] (4) The breakage rate of Example 2 was 5.2%, significantly lower than the 18.7% of Comparative Example 1, the 12.3% of Comparative Example 2, and the 15.9% of Comparative Example 3. Comparative Example 1 lacked a reasonable gradient pore structure, resulting in low mechanical strength and easy breakage. Comparative Example 2 was undoped and lacked structural strength. Comparative Example 3 lacked the protection of a carbon coating and was even more susceptible to breakage under pressure. This demonstrates that the gradient pore structure formed by staged pH control, doping enhancement, and carbon composite technology greatly enhanced the mechanical strength of the material and improved its stability during processing and use.

[0094] In summary, through detailed analysis of Example 2 and the data of each comparative example, it can be seen that the multi-layer structure spherical cobalt tetroxide production method of the present invention utilizes staged pH adjustment, doping enhancement and carbon composite process, and is significantly better than the comparative samples in performance indicators such as specific surface area, tap density, cycle retention rate and mechanical strength. It not only increases the specific surface area and provides more active sites for electrochemical reactions, but also enhances the structural stability and ensures the performance of the material in high temperature calcination and charge and discharge cycles, thereby comprehensively improving the charge and discharge performance and cycle life of the battery, demonstrating the advanced nature and superiority of the production method.

[0095] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for producing multi-layer spherical cobalt oxide, characterized in that: The following steps are involved: S1. Adding a soluble cobalt salt and a precipitant to deionized water and stirring to obtain a mixed solution 1; S2, adding a morphology directing agent to the mixed solution 1, stirring, and ultrasonically treating to obtain a mixed solution 2; S3, the mixed solution 2 is placed in a reactor, the pH of the mixed solution 2 is adjusted to 9-11 in stages, and the mixture is reacted at 60-80° C. for 3-5 hours to generate a hollow spherical precursor. After the reaction is completed, the precursor is washed, centrifuged, and dried; S4, calcining the treated precursor in stages: in the first stage, heating the temperature to 300-400° C. at a heating rate of 2-5° C. / min and keeping the temperature for 1-2 hours; in the second stage, heating the temperature to 500-600° C. at a heating rate of 5-8° C. / min and keeping the temperature for 2-3 hours to form a multilayer spherical cobalt oxide; In step S2, a dopant is further added to the mixed solution 1, wherein the dopant is manganese nitrate, and the dopant amount of the manganese nitrate is 0.5-5% of the molar amount of the cobalt salt; In step S3, the pH value of the mixed solution 2 is adjusted in stages: a. In the first stage, the pH of the mixed solution 2 is adjusted to 8-9, and the mixture is reacted in a reactor at 60-70°C for 1-2 hours to form a dense core layer; b. In the second stage, the pH of the mixed solution 2 is adjusted to 10-11, and the reaction is carried out in a reactor at 70-80 ° C for 2-3 hours to generate a porous shell layer, thereby forming a core-shell gradient pore structure; After the calcination, the step S4 further comprises: Carbon source composite treatment: The calcined product is mixed with a carbon source and calcined at 700-800°C for 1-2 hours to form a carbon coating layer.

2. The method for producing multi-layer spherical cobalt oxide according to claim 1, characterized in that: The morphology directing agent includes citric acid and sodium lauryl sulfate, the molar ratio of the citric acid to the cobalt salt is 1:(1-2), and the mass ratio of the citric acid to sodium lauryl sulfate is 1:(0.1-0.5).

3. The method for producing multi-layer spherical cobalt oxide according to claim 1, characterized in that: During the calcination process in step S4, a mixed gas of nitrogen and air is introduced, and the volume of the nitrogen accounts for 10-30% of the volume of the mixed gas.

4. The method for producing multi-layer spherical cobalt oxide according to claim 1, characterized in that: The carbon source is one of glucose, polyvinyl pyrrolidone or graphene, and the mass ratio of the carbon source to the calcined product is (0.1-0.3):

1.

5. The method for producing multi-layer spherical cobalt oxide according to claim 1, characterized in that: The precipitant in step S1 is one of sodium hydroxide, sodium carbonate or ammonia water, and the molar ratio of the precipitant to the cobalt salt is (2-4):1.

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