Positive electrode active material for alkaline battery and preparation method of positive electrode active material

Abstract

The invention discloses a positive electrode active material for an alkaline battery, and belongs to the technical field of battery materials. The positive electrode material is prepared from the following raw materials in parts by weight: 100-120 parts of modified manganese dioxide, 0.5-0.8 part of an additive, 1-3 parts of carbon nanotubes, 0.2-0.4 part of polyvinyl alcohol and 3-5 parts of a positive electrode electrolyte. The prepared modified manganese dioxide has a flower-ball-shaped layered three-dimensional structure, the flower-ball-shaped layered three-dimensional structure is composed of a plurality of irregular sheets, the structure has high porosity and short diffusion length, and an efficient transmission path is provided for zinc ions, so that the zinc ions can be diffused and migrated in the material more easily; therefore, the charge-discharge rate and the cycle performance of the battery are improved, and the material can be used as an alkaline battery positive electrode material, and especially has a very wide application prospect in secondary zinc-manganese batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials, and particularly relates to a positive electrode active material for an alkaline battery and a preparation method thereof. Background Art

[0002] With the development of society, the energy crisis and environmental problems have become increasingly serious. As a new type of environmentally friendly energy storage device, secondary batteries have been widely used, ranging from daily portable electronic devices such as mobile phones, computers, and digital cameras to electric vehicles and even large-scale energy storage power grids. Under the background of vigorously promoting energy conservation and environmental protection, various batteries have developed rapidly, such as lead-acid batteries and lithium-ion batteries, which occupy a large market share. At present, the reversible capacity of lithium-ion secondary batteries can reach 200 mAh·g -1 , and the energy density reaches 260 Wh·kg -1 , and the cycle life exceeds 1000 times; lead-acid batteries are inexpensive and easy to obtain, and are easy to recycle, and the reversible capacity is maintained at about 100 mAh·g -1 . However, lithium-ion batteries have high costs, limited lithium resources, and poor safety, while lead-acid batteries have low energy density, short working life, contain heavy metals, and are not environmentally friendly. Therefore, it is particularly important to develop secondary batteries with high capacity, fast charge and discharge, good safety, rich raw material resources, environmental friendliness, and strong adaptability.

[0003] Common alkaline secondary batteries include nickel-iron batteries, nickel-cadmium batteries, nickel-zinc batteries, nickel-metal hydride batteries, silver-zinc batteries, zinc-manganese batteries, etc. Among them, zinc-manganese secondary batteries generally use MnO2 as the positive electrode, Zn as the negative electrode, and KOH solution as the electrolyte. During discharge, the Zn negative electrode undergoes an oxidation reaction, releasing electrons to the external circuit. The electrons move to the MnO2 positive electrode and undergo a reduction reaction. Inside the battery, ions move between the positive and negative electrodes with the help of the electrolyte. During charging, under the action of an externally applied reverse current, the positive and negative electrode reactions proceed in the reverse direction, and the active substances at both electrodes return to their initial states, converting electrical energy into chemical energy. Zinc-manganese secondary batteries have the advantages of low self-discharge, no memory effect, simple structure, low energy consumption, and environmental friendliness. They can not only improve resource utilization but also significantly reduce environmental pollution caused by battery waste. Among them, manganese dioxide as the positive electrode material is inexpensive, environmentally friendly, has multiple variable valence states, and has strong ion storage performance. It is the most commonly used positive electrode material for traditional zinc-manganese batteries in recent years. Although manganese dioxide has many advantages as the positive electrode material for zinc-manganese batteries, there are still some problems: (1) The conductivity of the positive electrode MnO2 is poor, resulting in the electrochemical reaction occurring only on the electrode surface, which greatly limits the utilization rate of the electrode material; (2) Most MnO2 materials have problems such as unstable structure and easy conversion to other valence states. During the charge and discharge process, electrochemically inert Mn3O4 is generated and serious volume expansion occurs, making the deep charge and discharge reversibility of MnO2 poor and the cycle performance not ideal. Therefore, it is urgently necessary to further research and seek MnO2 positive electrode materials that are inexpensive, have a stable structure, good cycle performance, and are suitable for large-scale production to meet market demands. Summary of the Invention

[0004] The purpose of the present invention is to provide a positive electrode active material for alkaline batteries, which can improve the structural stability and conductivity of the positive electrode material MnO2, thereby further improving the electrochemical performance of battery materials.

[0005] To achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A positive electrode active material for alkaline batteries is made from the following raw materials in parts by weight: 100 - 120 parts of modified manganese dioxide, 0.5 - 0.8 parts of additive, 1 - 3 parts of carbon nanotubes, 0.2 - 0.4 parts of polyvinyl alcohol, and 3 - 5 parts of positive electrode electrolyte.

[0007] Preferably, the modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer to a microwave hydrothermal reaction kettle, set the heating rate to rise to 100 °C, keep the temperature for the reaction, after the reaction is completed, cool to room temperature, centrifuge, wash the solid product several times with absolute ethanol and deionized water, and dry the precipitate at 80 °C to obtain modified flower-like manganese dioxide.

[0008] Preferably, the specific method for setting the heating rate is: Raise the temperature to 100 °C within 2 min.

[0009] Preferably, the reaction time for keeping the temperature is 5 min.

[0010] Preferably, the additive is one of cerium oxide, indium oxide, and neodymium oxide.

[0011] Preferably, the carbon nanotubes are single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0012] Preferably, the positive electrode electrolyte is an aqueous potassium hydroxide solution with a mass concentration of 35%.

[0013] The present invention also provides a preparation method for the positive electrode active material of the above alkaline battery, which includes the following steps:

[0014] (1) Prepare modified manganese dioxide;

[0015] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate to obtain the positive electrode material, and then coat it onto a titanium mesh that has been cleaned with alcohol through a doctor blade. The titanium mesh is taken out after drying in an oven at 60 °C for 12 h, and the titanium foil is cut into positive electrode sheets with a cutting machine for use.

[0016] The beneficial effects of the present invention are as follows: The modified manganese dioxide prepared by the present invention has a flower-like spherical hierarchical three-dimensional structure. The flower-like spherical three-dimensional structure is composed of many irregular thin flakes. This structure has a high porosity and a short diffusion length, providing an efficient transmission path for zinc ions, enabling zinc ions to diffuse and migrate more easily in the material, thereby improving the charge and discharge rate and cycling performance of the battery. At the same time, the doping of copper-lithium ions can significantly increase the conductivity of the manganese dioxide material, which helps to improve the charge transport efficiency inside the battery, thereby reducing the internal resistance of the battery and improving the output performance of the battery. The synergistic effect of copper ions and lithium ions can also improve the conductivity of manganese dioxide and the stability of the manganese dioxide tunnel structure, increase ion and electron defects, change the effective reaction surface, electron and ion transport ability of MnO2, and can also promote the kinetics of the redox reaction on the material surface, thereby realizing the improvement of the battery capacity. At the same time, it can better maintain the structural integrity during the charge and discharge process, which helps to extend the service life and cycling stability of the battery. Therefore, the electrode active material prepared by the present invention can be used as the positive electrode material of alkaline batteries, especially in the application of secondary zinc-manganese batteries, and has a very broad application prospect. Description of the Drawings

[0017] Figure 1 SEM micrograph of the microscopic morphology of the modified manganese dioxide prepared by the present invention;

[0018] Figure 2 Test result graph of electrochemical impedance of different embodiments of the present invention;

[0019] Figure 3 Test result graph of cyclic voltammetry of the positive electrode active material of different embodiments of the present invention;

[0020] Figure 4 Cycling performance graph of the full battery assembled with different embodiments of the present invention at a 1C rate. Detailed Embodiments

[0021] The technical solutions of the present invention will be further described below in conjunction with specific embodiments, but not limited thereto.

[0022] Example 1

[0023] A positive electrode active material for alkaline batteries is made from the following raw materials in parts by weight: 120 parts of modified manganese dioxide, 0.8 part of additive, 3 parts of carbon nanotubes, 0.4 part of polyvinyl alcohol, and 5 parts of positive electrode electrolyte.

[0024] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer to a microwave hydrothermal reaction kettle, set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool to room temperature, centrifuge, wash the solid product with anhydrous ethanol and deionized water several times, and dry the precipitate at 80 °C to obtain modified spherical manganese dioxide.

[0025] The additive is cerium oxide.

[0026] The carbon nanotubes are single-walled carbon nanotubes.

[0027] The positive electrode electrolyte is an aqueous solution of potassium hydroxide with a mass concentration of 35%.

[0028] A preparation method of the above-mentioned positive electrode active material for alkaline batteries, which includes the following steps:

[0029] (1) Prepare modified manganese dioxide;

[0030] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate to obtain the positive electrode material, and then coat it onto a titanium mesh cleaned with alcohol through a doctor blade. The titanium mesh is taken out after drying in an oven at 60 °C for 12 h, and the titanium foil is cut into positive electrode sheets for use with a cutting machine.

[0031] Example 2

[0032] A positive electrode active material for alkaline batteries is made from the following raw materials in parts by weight: 100 parts of modified manganese dioxide, 0.5 part of additive, 1 part of carbon nanotubes, 0.2 part of polyvinyl alcohol, and 3 parts of positive electrode electrolyte.

[0033] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue stirring for 10 min, then transfer to a microwave hydrothermal reaction kettle, set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool to room temperature, centrifuge, wash the solid product several times with absolute ethanol and deionized water, and dry the precipitate at 80 °C to obtain modified flower-like manganese dioxide.

[0034] The additive is indium oxide.

[0035] The carbon nanotubes are multi-walled carbon nanotubes.

[0036] The positive electrode electrolyte is an aqueous potassium hydroxide solution with a mass concentration of 35%.

[0037] A preparation method of the positive electrode active material of the above-mentioned alkaline battery, which comprises the following steps:

[0038] (1) Prepare modified manganese dioxide;

[0039] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate, and it is the positive electrode material. Then coat it onto a titanium mesh cleaned with alcohol through a doctor blade die. Take out the titanium mesh after drying in an oven at 60 °C for 12 h, and cut the titanium foil into positive electrode sheets for use.

[0040] Example 3

[0041] A positive electrode active material for an alkaline battery, which is made from the following raw materials in parts by weight: 110 parts of modified manganese dioxide, 0.7 part of additive, 2 parts of carbon nanotubes, 0.3 part of polyvinyl alcohol, and 4 parts of positive electrode electrolyte.

[0042] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue stirring for 10 min, then transfer it into a microwave hydrothermal reaction kettle, set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool it to room temperature, centrifuge, wash the solid product with anhydrous ethanol and deionized water for several times, and dry the precipitate at 80 °C to obtain modified spherical manganese dioxide.

[0043] The additive is neodymium oxide.

[0044] The carbon nanotubes are single-walled carbon nanotubes.

[0045] The positive electrode electrolyte is an aqueous solution of potassium hydroxide with a mass concentration of 35%.

[0046] A preparation method of the positive electrode active material of the above alkaline battery, which comprises the following steps:

[0047] (1) Prepare modified manganese dioxide;

[0048] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate to obtain the positive electrode material, and then coat it onto a titanium mesh cleaned with alcohol through a doctor blade die. After the titanium mesh is dried in an oven at 60 °C for 12 h, take it out, and cut the titanium foil into positive electrode sheets for use.

[0049] Example 4

[0050] A positive electrode active material for an alkaline battery, which is made of the following raw materials in parts by weight: 110 parts of modified manganese dioxide, 0.6 part of additive, 2 parts of carbon nanotubes, 0.3 part of polyvinyl alcohol, and 5 parts of positive electrode electrolyte.

[0051] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer it into a microwave hydrothermal reaction kettle, set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool it to room temperature, centrifuge, wash the solid product several times with absolute ethanol and deionized water, and dry the precipitate at 80 °C to obtain modified flower-like manganese dioxide.

[0052] The additive is one of indium oxides.

[0053] The carbon nanotubes are single-walled carbon nanotubes.

[0054] The positive electrode electrolyte is an aqueous potassium hydroxide solution with a mass concentration of 35%.

[0055] A preparation method of the positive electrode active material for the above alkaline battery includes the following steps:

[0056] (1) Prepare modified manganese dioxide;

[0057] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate, and it is the positive electrode material. Then coat it onto a titanium mesh that has been cleaned with alcohol through a slitting die. Take out the titanium mesh after drying it in an oven at 60 °C for 12 h, and cut the titanium foil into positive electrode sheets for use.

[0058] Example 5

[0059] A positive electrode active material for an alkaline battery is made from the following raw materials in parts by weight: 120 parts of modified manganese dioxide, 0.8 part of additive, 1 part of carbon nanotubes, 0.2 part of polyvinyl alcohol, and 4 parts of positive electrode electrolyte.

[0060] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer it into a microwave hydrothermal reaction kettle, set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool it to room temperature, centrifuge, wash the solid product with anhydrous ethanol and deionized water for several times, and dry the precipitate at 80 °C to obtain modified flower-like manganese dioxide.

[0061] The additive is neodymium oxide.

[0062] The carbon nanotubes are single-walled carbon nanotubes.

[0063] The positive electrode electrolyte is an aqueous potassium hydroxide solution with a mass concentration of 35%.

[0064] A preparation method of the positive electrode active material of the above alkaline battery, which comprises the following steps:

[0065] (1) Prepare modified manganese dioxide;

[0066] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate to obtain the positive electrode material, and then coat it onto the titanium mesh cleaned with alcohol through a doctor blade die. Take out the titanium mesh after drying in an oven at 60 °C for 12 h, and cut the titanium foil into positive electrode sheets for use.

[0067] Comparative Example 1

[0068] A positive electrode active material for an alkaline battery, which is made from the following raw materials in parts by weight: 120 parts of modified manganese dioxide, 0.8 part of additive, 1 part of carbon nanotubes, 0.2 part of polyvinyl alcohol, and 4 parts of positive electrode electrolyte.

[0069] The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 20 mg of urea and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer it into a microwave hydrothermal reaction kettle, and set the temperature to rise to 100 °C within 2 min, keep the temperature for reaction for 5 min, after the reaction is completed, cool it to room temperature, centrifuge, wash the solid product with absolute ethanol and deionized water several times, and dry the precipitate at 80 °C to obtain modified spherical manganese dioxide.

[0070] The additive is neodymium oxide.

[0071] The carbon nanotubes are single-walled carbon nanotubes.

[0072] The positive electrode electrolyte is an aqueous solution of potassium hydroxide with a mass concentration of 35%.

[0073] A preparation method of the positive electrode active material of the above alkaline battery includes the following steps:

[0074] (1) Prepare modified manganese dioxide;

[0075] (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate, and it is the positive electrode material. Then coat it onto the titanium mesh cleaned with alcohol through a doctor blade die. Take out the titanium mesh after drying in an oven at 60 °C for 12 h, and cut the titanium foil into positive electrode sheets with a cutting machine for use.

[0076] In this comparative example, except that copper acetate anhydrous is not added in the preparation method of the modified manganese dioxide, other raw materials and preparation methods are the same as those in Example 5.

[0077] Comparative Example 2

[0078] In this comparative example, except that lithium nitrate is not added in the preparation method of the modified manganese dioxide, other raw materials and preparation methods are the same as those in Example 5.

[0079] Comparative Example 3

[0080] In this comparative example, except that copper acetate anhydrous and lithium nitrate are not added in the preparation method of the modified manganese dioxide, other raw materials and preparation methods are the same as those in Example 5.

[0081] Comparative Example 4

[0082] A positive electrode active material for an alkaline battery, which is made from the following raw materials in parts by weight: 120 parts of manganese dioxide, 0.8 part of additive, 1 part of carbon nanotube, 0.2 part of polyvinyl alcohol, and 4 parts of positive electrode electrolyte.

[0083] The manganese dioxide used in this comparative example is a commercially available raw material. Other raw materials are the same as those in Example 5.

[0084] A preparation method of a positive electrode active material for an alkaline battery includes the following steps: Mix manganese dioxide, additive, carbon nanotube, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, and evacuate to obtain the positive electrode material. Then coat it onto a titanium mesh cleaned with alcohol through a slitting die. Take out the titanium mesh after drying it in an oven at 60°C for 12 h, and cut the titanium foil into positive electrode sheets for use.

[0085] Performance Test

[0086] The microscopic morphology of the modified manganese dioxide positive electrode active material obtained in Example 5 was analyzed by scanning electron microscopy, specifically as Figure 1 shown. The modified manganese dioxide prepared in Example 5 has a flower-ball-shaped hierarchical three-dimensional structure. The flower-ball-shaped three-dimensional structure is composed of many irregular thin sheets, and the diameter of the flower ball is 2 - 3 μm. This structure has a high porosity and a short diffusion length, providing an efficient transmission path for zinc ions, enabling zinc ions to diffuse and migrate more easily in the material, thereby improving the charge and discharge rate and cycle performance of the battery.

[0087] Using the positive electrode sheet obtained in Example 5 of the present invention as the positive electrode, a metal zinc sheet as the negative electrode, and an aqueous solution of potassium hydroxide with a mass concentration of 35% as the electrolyte, a full battery was assembled and tested.

[0088] Select the positive electrode active materials for alkaline batteries prepared in Example 5 and Comparative Examples 1 - 4, and perform AC impedance testing using an electrochemical analyzer. Electrochemical impedance testing parameters: The test frequency range is from 0.1×10 -6 to 1×10 6 Hz. The EIS spectrum and the corresponding fitting circuit are as Figure 2 shown. In the fitting circuit diagram, Rs and Rct are the electrolyte resistance and charge transfer resistance respectively, CPE1 is a constant phase angle element related to the interfacial resistance, and W0 is an element of the Warburg resistance. Among them, Rct can reflect the difficulty of the charge transfer process at the electrode / electrolyte interface. From Figure 2It can be seen that the impedance Rct of the positive electrode material prepared in Example 5 of the present invention is significantly lower than the impedance values of Comparative Examples 1-4. This indicates that the introduction of the copper-lithium bimetal in the electrode material prepared by the present invention and the synergistic effect of composite materials such as carbon nanotubes further enhance the conductivity of the material, and the electrochemical performance of the material is good.

[0089] The cyclic voltammetry (CV) curve was tested using a CHI 660E electrochemical workstation, and the scanning rate was 1 mV·s -1 , and the voltage range was 0.8 - 2.0 V. The results are as Figure 3 shown. It can be seen from Figure 3 that the peak value of the cyclic voltammetry test of the positive electrode active material prepared in Example 5 of the present invention is the highest, which indicates that the battery assembled with the positive electrode sheet prepared by the present invention has a higher capacity. This is because the manganese dioxide material after doping with copper-lithium bimetal ions has higher activity and conductivity, and the structural stability of the prepared three-dimensional flower-like layered structure of MnO2 is further improved.

[0090] The charge / discharge test and cycle stability test of the zinc-manganese battery were carried out using a CT2001 battery test system, and the test condition was 1C. The results are as Figure 4 shown. It can be found that the cyclic performance of the positive electrode active material prepared in Example 5 of the present invention is good. Under the condition of 1C, the initial discharge specific capacity can reach 363 mAh / g, and the capacity retention rate is above 80% after 500 cycles, while Comparative Examples 1-4 decay more severely. This indicates that the positive electrode material prepared by the present invention has good cyclic performance and prolongs the service life of the battery.

[0091] It should be noted that the above embodiments are only some of the embodiments of the preferred ways to implement the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Claims

1. A positive electrode active material for an alkaline battery, characterized in that, It is made from the following raw materials in parts by weight: 100 - 120 parts of modified manganese dioxide, 0.5 - 0.8 part of additive, 1 - 3 parts of carbon nanotubes, 0.2 - 0.4 part of polyvinyl alcohol, and 3 - 5 parts of positive electrode electrolyte.

2. The positive electrode active material for an alkaline battery according to claim 1, wherein The modified manganese dioxide is prepared by the following method: Prepare 100 ml of 0.5 mol / L manganese sulfate solution, add 12.55 g of ammonium persulfate thereto, stir evenly with a magnetic stirrer, then add 50 ml of ethylene glycol and 5 mmol of sodium dodecylbenzenesulfonate, and stir and react at room temperature for 30 - 40 min; then add 1 mmol of anhydrous copper acetate, 20 mg of urea, and 1 mmol of lithium nitrate, continue to stir for 10 min, then transfer to a microwave hydrothermal reaction kettle, set the heating rate to rise to 100 °C, keep the temperature for reaction, after the reaction is completed, cool to room temperature, centrifuge, wash the solid product with anhydrous ethanol and deionized water several times, and dry the precipitate at 80 °C to obtain modified spherical manganese dioxide.

3. The positive electrode active material for an alkaline battery according to claim 2, characterized in that, The specific method for setting the heating rate is: Raise the temperature to 100 °C within 2 min.

4. The positive electrode active material for an alkaline battery according to claim 2, wherein, The reaction time for keeping the temperature is 5 min.

5. The positive electrode active material for an alkaline battery according to claim 1, characterized in that, The additive is one of cerium oxide, indium oxide, and neodymium oxide.

6. The positive electrode active material of the alkaline battery according to claim 1, characterized in that, The carbon nanotubes are single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

7. The positive electrode active material of the alkaline battery according to claim 1, characterized in that, The positive electrode electrolyte is an aqueous potassium hydroxide solution with a mass concentration of 35%.

8. A method for preparing a positive electrode active material of an alkaline battery according to any one of claims 1-7, characterized in that, It includes the following steps: (1) Prepare modified manganese dioxide; (2) Mix the modified manganese dioxide, additive, carbon nanotubes, and polyvinyl alcohol evenly to obtain a mixed powder. Ball-mill the mixed powder at a rotation speed of 300 - 400 r / min for 4 - 6 h, then add the positive electrode electrolyte, mix evenly, evacuate to obtain the positive electrode material, and then coat it onto a titanium mesh cleaned with alcohol through a slitting die. Take out the titanium mesh after drying it in an oven at 60 °C for 12 h, and cut the titanium foil into positive electrode sheets for use.

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