A battery cathode material, its preparation method, and the battery composition thereof

Abstract

The application belongs to the field of battery materials, and relates to a battery positive electrode material, a preparation method thereof and a battery composed of the battery positive electrode material. The battery positive electrode material comprises manganese dioxide nanowires and a conductive polymer, and the conductive polymer is coated on the surface of the manganese dioxide nanowires. The preparation method comprises the following steps: adding the manganese dioxide nanowires into a dispersion solvent, adjusting pH, and adding a polymer monomer for polymerization reaction to obtain the positive electrode material of the polymer-coated manganese dioxide nanowires. The manganese dioxide itself is used as an oxidizing agent to initiate the polymerization reaction of the conductive polymer, so that a conformal coating layer is formed on the surface of the manganese dioxide nanowires, the binding force between the coating layer and the manganese dioxide nanowires is stronger, the manganese dioxide itself is used as an oxidizing agent to initiate the polymerization reaction without adding an additional oxidizing agent, the reaction condition is mild, the initial nanowire morphology of the manganese dioxide nanowires is ensured, the coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, and thus the conductivity of the inner manganese dioxide nanowires is ensured.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, and relates to a battery cathode material, its preparation method, and a battery composed thereof. Background Technology

[0002] Aqueous zinc-ion batteries have attracted widespread attention due to their environmental friendliness, high safety, and low cost. Manganese dioxide (MCO), with its high specific capacity, high voltage plateau, and abundant reserves, is the most studied cathode material and holds great promise for large-scale applications. Different structural morphologies can impart different properties to the material. MCO nanowires, in particular, possess the advantages of one-dimensional metal oxide materials, exhibiting unique characteristics such as large surface area, abundant active sites, and rapid ion diffusion. However, when used as cathode materials in aqueous zinc-ion batteries, MCO nanowires still face serious structural collapse and poor conductivity issues, hindering their further development.

[0003] To address the above issues, current solutions include conductive material coating, ion doping, and the creation of oxygen vacancies. However, these solutions often only address one aspect of the problem. For example, conductive material coating can improve the structural stability and outer conductivity of the material, but it cannot simultaneously improve the conductivity of the inner layer. Ion doping can improve the structural stability of the material, but it cannot improve the conductivity. Oxygen vacancies can improve the internal conductivity of the material, but they are less effective in improving structural stability. Therefore, to simultaneously improve the structural stability of the material, as well as the internal and external conductivity, it is necessary to combine two or more modification methods. This results in overly complex procedures that cannot be achieved in a single step, and the controllability of the intermediate processes is reduced, potentially damaging the intrinsic structure of the manganese dioxide nanowires, making it difficult to achieve the desired modification effect. Summary of the Invention

[0004] The present invention aims to provide a battery cathode material, its preparation method, and the battery composition thereof. Manganese dioxide itself acts as an oxidant to initiate the polymerization reaction of a conductive polymer on the surface of manganese dioxide nanowires. Through a one-step reaction, a conformal coating layer is formed on the surface of the manganese dioxide nanowires, reducing the self-polymerization products of the conductive polymer. The conformal coating layer has a stronger bonding force with the manganese dioxide nanowires. Since manganese dioxide itself acts as the oxidant, no additional oxidant is needed, and the reaction conditions are mild, ensuring the initial nanowire morphology of the manganese dioxide nanowires. The conductive polymer coating effectively stabilizes the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner manganese dioxide nanowires and improving the cycle stability of the polymer-coated manganese dioxide nanowires. Simultaneously, the conformal coating of the conductive polymer introduces oxygen vacancies, which improves electron transport in the polymer-coated manganese dioxide nanowires. Based on the improved conductivity of the conductive polymer, the conductivity of the polymer-coated manganese dioxide nanowires is further enhanced.

[0005] In a first aspect, the present invention provides a battery cathode material comprising manganese dioxide nanowires and a conductive polymer, wherein the conductive polymer is coated on the surface of the manganese dioxide nanowires.

[0006] Both conductive polymers and manganese dioxide nanowires possess high conductivity. Coating the surface of manganese dioxide nanowires with conductive polymers ensures the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner layer of manganese dioxide nanowires. The combination of these two structures further improves the conductivity and stability of the manganese dioxide nanowires coated with conductive polymers.

[0007] In some embodiments, the battery cathode material has oxygen vacancies.

[0008] The conformal coating of conductive polymers enables the introduction of oxygen vacancies, which can improve electron transport in manganese dioxide nanowires coated with conductive polymers. Based on the improved conductivity of conductive polymers, the conductivity of manganese dioxide nanowires coated with conductive polymers is further improved, thereby enhancing the rate performance of manganese dioxide nanowires coated with conductive polymers.

[0009] In some embodiments, the conductive polymer includes at least one of 3,4-ethylenedioxythiophene polymer, pyrrole polymer, and aniline polymer.

[0010] 3,4-ethylenedioxythiophene polymers, pyrrole polymers, and aniline polymers, used as coating layers for cathode materials, not only possess excellent conductivity themselves, but also exhibit stronger bonding with manganese dioxide nanowires. This effectively stabilizes the structure of manganese dioxide nanowires, facilitates the introduction of oxygen vacancies, and enhances electron transport within the polymer-coated manganese dioxide nanowires, thereby improving their conductivity.

[0011] In some embodiments, the manganese dioxide nanowires are prepared by a hydrothermal reaction of ammonium sulfate, manganese sulfate, and ammonium persulfate;

[0012] Preferably, the molar ratio of ammonium sulfate, manganese sulfate and persulfate is 3-5:0.5-1.5:1;

[0013] Preferably, the hydrothermal reaction temperature is 150-200℃, and the hydrothermal reaction time is 20-30 h.

[0014] The prepared manganese dioxide nanowires have a more stable structure and better conductivity. Batteries made using the prepared manganese dioxide nanowires as positive electrodes have better specific capacity and stability.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned cathode material, comprising the following steps:

[0016] Manganese dioxide nanowires were added to a dispersion solvent, the pH range was adjusted, polymer monomers were added and mixed, and a polymerization reaction was carried out to obtain manganese dioxide nanowires coated with a positive electrode material polymer.

[0017] Adding manganese dioxide nanowires to a dispersion solvent makes it easier to mix them with polymer monomers. Using manganese dioxide itself as an oxidant initiates the polymerization reaction of the conductive polymer on the surface of the manganese dioxide nanowires. This one-step reaction forms a conformal coating layer on the surface of the manganese dioxide nanowires, reducing the products of self-polymerization of the conductive polymer. The conformal coating layer has a stronger bond with the manganese dioxide nanowires. Since manganese dioxide itself acts as the oxidant, no additional oxidant is needed, and the reaction conditions are mild, ensuring the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer effectively stabilizes the structure of the manganese dioxide nanowires, thus ensuring the conductivity of the inner layer. The resulting manganese dioxide nanowires have a more stable structure and better conductivity.

[0018] In some implementations, the pH range is 2.5-4.5;

[0019] Preferably, the pH range is 3-4.

[0020] The pH of the polymerization reaction also affects the structure of the conductive polymer-coated manganese dioxide nanowires, thus affecting their conductivity. Ultimately, it was found that conductive polymer-coated manganese dioxide nanowires prepared with a polymerization reaction pH in the range of 3-4 have higher specific capacity and stability.

[0021] In some embodiments, the manganese dioxide nanowires are mixed with the polymer monomer at a mass ratio of 0.5-2.5:1;

[0022] Preferably, the manganese dioxide nanowires and the polymer monomers are mixed in a mass ratio of 1-2:1; the polymer monomers include at least one of 3,4-ethylenedioxythiophene monomer, pyrrole monomer, and aniline monomer.

[0023] Within this ratio of manganese dioxide nanowires to polymer monomers, the coating layer can both completely and uniformly coat the manganese dioxide nanowires and maximize conductivity. When the amount of conductive polymer monomers is too small, such as when the mass ratio of conductive polymer monomers to manganese dioxide nanowires is less than 0.5, the conductivity and rate performance of the resulting polymer-coated manganese dioxide nanowires are low due to the small amount of conductive polymer layer coated on the surface of the manganese dioxide nanowires. Conversely, when the amount of conductive polymer monomers is too large, such as when the mass ratio of conductive polymer monomers to manganese dioxide nanowires is greater than 2.5, the specific capacity and capacity retention of the battery composed of the polymer-coated manganese dioxide nanowire cathode material actually decrease.

[0024] 3,4-Ethylenedioxythiophene polymers, pyrrole polymers, and aniline polymers possess excellent conductivity and exhibit stronger bonding with manganese dioxide nanowires. This effectively stabilizes the structure of manganese dioxide nanowires, facilitates the introduction of oxygen vacancies, and enhances electron transport in the polymer-coated manganese dioxide nanowires, thereby improving their conductivity.

[0025] In some embodiments, the manganese dioxide nanowires are prepared by a hydrothermal reaction of ammonium sulfate, manganese sulfate, and ammonium persulfate.

[0026] Preferably, the molar ratio of ammonium sulfate, manganese sulfate, and persulfate is 3-5:0.5-1.5:1;

[0027] Preferably, the hydrothermal reaction temperature is 150-200℃, and the hydrothermal reaction time is 20-30 h.

[0028] When the molar ratio of ammonium sulfate, manganese sulfate, and persulfate is 3-5:0.5-1.5:1 and the reaction temperature is within the range of 150-200℃, the manganese dioxide nanowires prepared as the positive electrode of the battery have good specific capacity and stability.

[0029] In a third aspect, the present invention provides a battery comprising any of the above-described positive electrode materials.

[0030] Since the conductive polymer and manganese dioxide nanowires in the cathode material have high conductivity, the coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires and ensure the conductivity of the inner manganese dioxide nanowires. The combination of the two structures further improves the conductivity and stability of the manganese dioxide nanowires coated with conductive polymer. The battery made using this cathode material has higher specific capacity and stability.

[0031] In a fourth aspect, the present invention provides a method for preparing a battery, comprising the following steps:

[0032] S1. Preparation of battery positive electrode: The battery positive electrode material according to any one of claims 1-4 or the positive electrode material prepared by the preparation method according to any one of claims 5-8 is added to N-methylpyrrolidone and mixed into a uniform slurry. The slurry is coated on titanium foil to prepare a zinc-ion battery positive electrode.

[0033] S2. Battery preparation: Using zinc sheet as negative electrode, glass fiber as separator, and zinc sulfate as electrolyte, assemble into button cell;

[0034] Preferably, the mass ratio of the positive electrode material, acetylene black, and polyvinylidene fluoride is 5-10:0.5-2:1;

[0035] Preferably, the solid content of the slurry is 55% to 60%.

[0036] When the mass ratio of cathode material, acetylene black, and polyvinylidene fluoride is 5-10:0.5-2:1, and the solid content of the slurry is 55%~60%, the ratio of cathode material to N-methylpyrrolidone can be guaranteed, and the resulting battery has higher specific capacity and stability.

[0037] In summary, this application includes at least one of the following beneficial technical effects:

[0038] Both conductive polymers and manganese dioxide nanowires possess high conductivity. Coating the surface of manganese dioxide nanowires with conductive polymers ensures the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner layer of manganese dioxide nanowires. The combination of these two structures further improves the conductivity and stability of the manganese dioxide nanowires coated with conductive polymers. Attached Figure Description

[0039] Figure 1 This is a SEM image of the PEDOT-coated manganese dioxide nanowires from Example 1.

[0040] Figure 2 The images show the Raman spectra of manganese dioxide, PEDOT, and PEDOT-coated manganese dioxide in Example 5.

[0041] Figure 3 The image shows the electron paramagnetic resonance (EPR) spectrum of the manganese dioxide nanowires coated with manganese dioxide and PEDOT in Example 5.

[0042] Figure 4 The graphs show the rate performance of the batteries in Example 5 and Comparative Example 1 at different current densities.

[0043] Figure 5 The graph shows the cycle performance of the batteries in Example 5 and Comparative Example 1 after 500 cycles at a current density of 0.4 A / g. Detailed Implementation

[0044] The following specific embodiments further illustrate the technical solution of the present invention. These specific embodiments do not represent a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention.

[0045] Currently, manganese dioxide nanowires, when used as cathode materials in aqueous zinc-ion batteries, suffer from severe structural collapse and poor conductivity. Solutions include conductive material coating, ion doping, and the creation of oxygen vacancies. However, these methods often only address one aspect of the problem. For example, conductive material coating can improve the structural stability and outer layer conductivity, but cannot simultaneously improve the conductivity of the inner layer. Ion doping can improve structural stability but not conductivity. Oxygen vacancies can improve internal conductivity but are less effective in maintaining structural stability. Therefore, to simultaneously improve both structural stability and internal and external conductivity, a combination of two or more modification methods is required. This results in overly complex procedures that cannot be achieved in a single step, reduced controllability of intermediate processes, and potential damage to the intrinsic structure of the manganese dioxide nanowires, making it difficult to achieve the desired modification results.

[0046] Based on this, we attempted to prepare a new cathode material. Since manganese dioxide nanowires have a large specific surface area and abundant active sites, they can increase the reaction area between the material and zinc ions. Manganese dioxide nanowires can improve the overall specific capacity. Therefore, we chose manganese dioxide nanowires as the base material.

[0047] We explored combining different materials with manganese dioxide nanowires and ultimately found that using conductive polymers as coating materials to coat the surface of manganese dioxide nanowires resulted in conductive polymer-coated manganese dioxide nanowires with excellent conductivity in both the inner and outer layers. Furthermore, the structure was stable, exhibiting high cycle stability and rate performance. In the preparation process, a conductive structure could be coated onto the surface of manganese dioxide nanowires in a single reaction. Further analysis confirmed that the internal structure of the resulting material remained manganese dioxide nanomaterials, thus the inner layer possessed high conductivity. Analysis showed that the outer coating layer was primarily a product of the polymerization reaction of conductive polymer monomers, exhibiting high conductivity and stability. Numerous oxygen vacancies were also found in this structural layer.

[0048] Analysis of the results shows that manganese dioxide itself acts as an oxidant, initiating the polymerization reaction of conductive polymer monomers on the surface of manganese dioxide nanowires. This one-step reaction forms a conformal coating layer on the surface of the manganese dioxide nanowires, reducing the self-polymerization products of the conductive polymer in solution. Adding additional oxidants leads to the formation of more self-polymerized conductive polymers in solution, affecting the coating effect of the conductive polymer layer on the manganese dioxide surface. The conductive polymer can only polymerize on the surface of manganese dioxide nanowires to form a conformal coating layer. The conformal coating layer has a stronger binding force with the manganese dioxide nanowires. Since manganese dioxide itself acts as an oxidant, self-initiation does not require the addition of additional oxidants, and the reaction conditions are mild, ensuring the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer effectively stabilizes the structure of the manganese dioxide nanowires, thus ensuring the conductivity of the inner layer and improving the cycle stability of the coated manganese dioxide nanowires. Simultaneously, the conductive polymer also enhances the electronic conductivity of the manganese dioxide nanowires.

[0049] Furthermore, the conformal coating of conductive polymers enables the introduction of oxygen vacancies, which can improve electron transport in manganese dioxide nanowires coated with conductive polymers. Based on the improved conductivity of conductive polymers, the conductivity of manganese dioxide nanowires coated with conductive polymers is further improved, thereby enhancing the rate performance of manganese dioxide nanowires coated with conductive polymers.

[0050] Furthermore, during the preparation of manganese dioxide nanowires, we found that not any conductive polymer can achieve the above-mentioned effect when coated on the surface of manganese dioxide nanowires. The conductive polymers that can achieve the above-mentioned effect are mainly 3,4-ethylenedioxythiophene monomer, pyrrole monomer, and aniline monomer. Among them, manganese dioxide nanowires coated with conductive polymer prepared by using 3,4-ethylenedioxythiophene monomer as a conductive polymer monomer, when used as the positive electrode of the battery, not only have a high specific capacity at different current densities, but also have the highest capacity retention rate.

[0051] The ratio of conductive polymer monomers to manganese dioxide nanowires is not arbitrary. When the amount of conductive polymer monomers is too small, such as when the mass ratio of conductive polymer monomers to manganese dioxide nanowires is less than 0.5, the conductivity and rate performance of the resulting polymer-coated manganese dioxide nanowires are low due to the smaller conductive polymer layer coating the surface of the manganese dioxide nanowires. Conversely, when the amount of conductive polymer monomers is too large, such as when the mass ratio of conductive polymer monomers to manganese dioxide nanowires is greater than 2.5, the specific capacity and capacity retention of the battery composed of the polymer-coated manganese dioxide nanowire cathode material actually decrease. Furthermore, the pH of the polymerization reaction also affects the structure of the polymer-coated manganese dioxide nanowires, thus influencing their conductivity. Ultimately, it was found that polymer-coated manganese dioxide nanowires prepared with a polymerization reaction pH in the range of 3-4 exhibit higher specific capacity and stability.

[0052] Meanwhile, the proportion of raw materials, temperature and time of the hydrothermal reaction were also adjusted during the experiment. When the molar ratio of ammonium sulfate, manganese sulfate and persulfate was 3-5:0.5-1.5:1 and the reaction temperature was in the range of 150-200℃, the manganese dioxide nanowires prepared as the positive electrode of the battery had good specific capacity and stability.

[0053] Example 1

[0054] A method for preparing a positive electrode material, wherein the positive electrode material is manganese dioxide nanowires coated with a conductive polymer, includes the following steps:

[0055] 1. Preparation of manganese dioxide nanowires

[0056] Ammonium sulfate, manganese sulfate, and ammonium persulfate were added to 200 mL of deionized water and stirred until completely dissolved. The solution was then transferred to a high-temperature reactor for hydrothermal reaction. Magnetic stirring was applied to the reaction solution. After the reaction was completed, the solution was centrifuged and dried to obtain manganese dioxide nanowires.

[0057] In some embodiments, the molar ratio of ammonium sulfate, manganese sulfate and persulfate is 3-5:0.5-1.5:1, such as 3:0.5:1, 4:1:1, 4:1.5:1, 5:0.5:1, etc.

[0058] In some embodiments, the temperature of the hydrothermal reaction is 150-200°C, and the time of the hydrothermal reaction is 20-30 h, such as a hydrothermal reaction temperature of 150°C and a hydrothermal reaction time of 30 h, a hydrothermal reaction temperature of 160°C and a hydrothermal reaction time of 28 h, etc.

[0059] In this embodiment, 20 mmol of ammonium sulfate, 5 mmol of manganese sulfate, and 5 mmol of ammonium persulfate were added to 200 mL of deionized water and stirred until completely dissolved. The solution was then transferred to a high-temperature reactor and subjected to a hydrothermal reaction at 180°C for 24 h. Simultaneously, the reaction solution was magnetically stirred. After the reaction was completed, the solution was centrifuged and dried to obtain manganese dioxide nanowires.

[0060] 2. Preparation of positive electrode material: manganese dioxide nanowires coated with conductive polymer.

[0061] Manganese dioxide nanowires were added to a dispersion solvent, the pH range was adjusted, polymer monomers were added and mixed, and a polymerization reaction was carried out to obtain manganese dioxide nanowires coated with a positive electrode material polymer.

[0062] In some embodiments, the pH range is adjusted to 2.5-4.5, such as pH 2.5, pH 3, pH 3.5, pH 4.5, etc.

[0063] In some embodiments, the mass ratio of manganese dioxide nanowires to the polymer monomer is 0.5-2.5:1, such as 0.5:1, 1:1, 2:1, or 2.5:1.

[0064] In some embodiments, the polymer monomer includes at least one of 3,4-ethylenedioxythiophene monomer, pyrrole monomer, and aniline monomer, such as the polymer monomer being one of 3,4-ethylenedioxythiophene monomer, pyrrole monomer, or aniline monomer; the polymer monomer being a mixture of the three monomers 3,4-ethylenedioxythiophene monomer, pyrrole monomer, and aniline monomer; the polymer monomer being a mixture of the two monomers 3,4-ethylenedioxythiophene monomer and pyrrole monomer; the polymer monomer being a mixture of the two monomers 3,4-ethylenedioxythiophene monomer and aniline monomer; the polymer monomer being a mixture of the two monomers pyrrole monomer and aniline monomer, etc.

[0065] In some embodiments, the dispersant is deionized water or pure water, etc.

[0066] In this embodiment, 1.0 g of the manganese dioxide nanowires obtained in step 1 were weighed and added to 500 mL of deionized water. The mixture was ultrasonically dispersed and continuously stirred. An appropriate amount of dilute hydrochloric acid was added to adjust the pH of the mixture to between 3 and 4. Then, 0.5 g of the conductive polymer monomer 3,4-ethylenedioxythiophene monomer was added. The mixture was ultrasonically dispersed and stirred at high speed. After polymerization for 12 h, the mixture was centrifuged and freeze-dried to obtain PEDOT-coated manganese dioxide nanowires (O...). v-MnO2@PEDOT), the resulting PEDOT-coated manganese dioxide nanowires are rich in oxygen vacancies.

[0067] Example 2

[0068] A method for preparing manganese dioxide nanowires coated with a conductive polymer as a positive electrode material differs from Example 1 in that the conductive polymer monomer in the step of preparing the manganese dioxide nanowires coated with the conductive polymer is a pyrrole monomer.

[0069] Example 3

[0070] A method for preparing a positive electrode material, manganese dioxide nanowires coated with a conductive polymer, differs from Example 1 in that, in the step of preparing the manganese dioxide nanowires coated with a conductive polymer, the conductive polymer monomer is an aniline monomer.

[0071] Example 4

[0072] A method for preparing manganese dioxide nanowires coated with a conductive polymer as a positive electrode material differs from Example 1 in that, in the step of preparing manganese dioxide nanowires coated with a conductive polymer, the amount of 3,4-ethylenedioxythiophene monomer added is 1.0 g.

[0073] Example 5

[0074] A method for preparing a button cell battery includes the following steps:

[0075] S1. Preparation of the battery positive electrode

[0076] The PEDOT-coated manganese dioxide nanowires prepared in Example 1 were added to N-methylpyrrolidone as the positive electrode material and mixed into a uniform slurry. The slurry was then coated onto titanium foil to prepare a zinc-ion battery positive electrode.

[0077] In some embodiments, the mass ratio of the cathode material, acetylene black, and polyvinylidene fluoride is 5-10:0.5-2:1, such as 5:0.5:1, 8:1:1, or 10:1.5:1.

[0078] In some embodiments, the solid content of the slurry is 55% to 60%, such as 55%, 56%, 57%, 58%, 59%, 60%, etc.

[0079] In this embodiment, the PEDOT-coated manganese dioxide nanowires rich in oxygen vacancies prepared in Example 1 are used as active materials. They are added to N-methylpyrrolidone in a mass ratio of active material, acetylene black and polyvinylidene fluoride of 8:1:1 and mixed into a uniform slurry. The solid content of the slurry is controlled at 55%. The slurry is coated on titanium foil to prepare a zinc-ion battery cathode.

[0080] S2, Battery fabrication

[0081] A CR2025 button cell is assembled using a zinc sheet as the negative electrode, glass fiber as the separator, and zinc sulfate as the electrolyte.

[0082] Example 6

[0083] A method for preparing a button cell battery includes the following steps:

[0084] S1. Preparation of battery cathode: The polypyrrole-coated manganese dioxide nanowires prepared in Example 2 are used as active materials. They are added to N-methylpyrrolidone in a mass ratio of active material, acetylene black and polyvinylidene fluoride of 8:1:1. The mixture is ground into a uniform slurry with a solid content of 55% to 60%. The slurry is coated on titanium foil to prepare a zinc-ion battery cathode.

[0085] S2. Battery preparation: Using zinc sheet as negative electrode, glass fiber as separator, and zinc sulfate as electrolyte, CR2025 button cell is assembled.

[0086] Example 7

[0087] A method for preparing a button cell battery includes the following steps:

[0088] S1. Preparation of battery cathode: The polyaniline-coated manganese dioxide nanowires prepared in Example 3 are used as active materials. They are added to N-methylpyrrolidone in a mass ratio of active material, acetylene black and polyvinylidene fluoride of 8:1:1. The mixture is ground into a uniform slurry with a solid content of 55% to 60%. The slurry is coated on titanium foil to prepare a zinc-ion battery cathode.

[0089] S2. Battery preparation: Using zinc sheet as negative electrode, glass fiber as separator, and zinc sulfate as electrolyte, CR2025 button cell is assembled.

[0090] Example 8

[0091] A method for preparing a button cell battery includes the following steps:

[0092] S1. Preparation of battery cathode: The PEDOT-coated manganese dioxide nanowires rich in oxygen vacancies prepared in Example 4 are used as active materials. They are added to N-methylpyrrolidone in a mass ratio of active material, acetylene black and polyvinylidene fluoride of 8:1:1. The mixture is ground into a uniform slurry with a solid content of 55% to 60%. The slurry is coated on titanium foil to prepare a zinc-ion battery cathode.

[0093] S2. Battery preparation: Using zinc sheet as negative electrode, glass fiber as separator, and zinc sulfate as electrolyte, CR2025 button cell is assembled.

[0094] Performance testing

[0095] 1. The button batteries obtained in Examples 5-8 were subjected to the following performance tests:

[0096] (1) Rate performance was tested at different current densities. The specific test method was to clamp the button cell battery onto the Xinwei Battery Tester. After confirming that the battery was normal and had no short circuit, the parameters were set on the BTS client on the control computer. The parameters set included the mass of the active material, the test current densities of 0.1, 0.2, 0.4, 0.8, 1.0, 1.5, 2.0, 3.0, and 5.0 A / g, the charging cut-off voltage of 1.8V, the discharging cut-off voltage of 0.8V, and 5 cycles at different current densities. The specific capacity, voltage, and other data for each cycle were recorded.

[0097] (2) Cycling performance was tested at a current density of 0.4 A / g. The specific test method was to clamp the button cell battery onto the Xinwei Battery Tester, check that the battery was normal and had no short circuit, and then set the parameters on the BTS client on the control computer. The parameters set included the mass of the active material, the test current density of 0.4 A / g, the charging cut-off voltage of 1.8 V, the discharging cut-off voltage of 0.8 V, and the number of cycles of 500. The specific capacity was recorded after the first and 500th cycles, and the battery capacity retention rate was calculated.

[0098] The test results are as follows:

[0099] Table 1 Performance test results of the button batteries prepared in Examples 5-8

[0100]

[0101] In this invention, conductive polymer-coated manganese dioxide nanowires are obtained by coating the surface of manganese dioxide nanowires with conductive polymer as the coating material. The resulting battery, which is then used as the positive electrode material, exhibits high specific capacity and high capacity retention at different current densities.

[0102] The reason for this may be that manganese dioxide itself acts as an oxidant, initiating the polymerization reaction of conductive polymer monomers on the surface of manganese dioxide nanowires. This one-step reaction forms a conformal coating layer on the surface of the manganese dioxide nanowires, reducing the products of self-polymerization of the conductive polymer. The conductive polymer can only polymerize on the surface of the manganese dioxide nanowires to form a conformal coating layer. The conformal coating layer has a stronger binding force with the manganese dioxide nanowires. Since manganese dioxide itself acts as an oxidant, no additional oxidant is needed, and the reaction conditions are mild, ensuring the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner layer of manganese dioxide nanowires and improving the cycle stability of the manganese dioxide nanowires coated with conductive polymer. At the same time, the conductive polymer can also improve the electronic conductivity of the manganese dioxide nanowires.

[0103] Furthermore, the conformal coating of the conductive polymer introduces oxygen vacancies, which improves electron transport in the polymer-coated manganese dioxide nanowires. This further enhances the conductivity of the polymer-coated manganese dioxide nanowires, thereby improving their rate performance. These factors combined result in excellent conductivity in both the inner and outer layers of the polymer-coated manganese dioxide nanowires, along with structural stability, leading to high cycle stability and rate performance in the fabricated battery.

[0104] In Example 5, the manganese dioxide nanowires coated with conductive polymer, prepared using 3,4-ethylenedioxythiophene monomer as the conductive polymer monomer, served as the positive electrode of the battery. This showed superior performance compared to the manganese dioxide nanowires coated with conductive polymer prepared using pyrrole monomer and aniline monomer as the conductive polymer monomers in Examples 6 and 7, respectively. However, in Example 8, the mass of both the conductive polymer monomer and the manganese dioxide nanowires in the manganese dioxide nanowires coated with conductive polymer as the positive electrode was greater than in Example 5. The resulting battery exhibited lower specific capacity and capacity retention at different current densities compared to Example 5. This demonstrates that a higher content of conductive polymer monomer does not necessarily improve the specific capacity of the battery.

[0105] 2. The PEDOT-coated manganese dioxide nanowires prepared in Example 1 were surface-scanned using a high-energy electron beam (SEM) image, as shown below. Figure 1 As shown.

[0106] from Figure 1As can be seen from Example 1, the aspect ratio of the PEDOT-coated manganese dioxide nanowires exceeds 100, indicating that the PEDOT-coated manganese dioxide nanowires have a large specific surface area and abundant active sites, which can increase the reaction area between the material and zinc ions and improve the specific capacity of the material. This demonstrates that the in-situ PEDOT coating of manganese dioxide initiated by itself does not damage the structure of the manganese dioxide nanowires, ensuring the initial nanowire morphology. The coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner layer manganese dioxide nanowires and improving the cycle stability of the polymer-coated manganese dioxide nanowires.

[0107] 3. Raman spectroscopy was used to test the manganese dioxide nanowires, PEDOT, and PEDOT-coated manganese dioxide nanowires in Example 5. The specific testing method was as follows: The Raman spectrometer was turned on, and the control software was started. The material was prepared as powder and spread evenly on a glass slide. The slide was placed on the sample stage of the Raman spectrometer, and the sample was focused using a microscope to ensure the laser beam accurately irradiated the test area of ​​the sample. The wavelength range for the test was set to 200–2000 cm⁻¹ on the control computer. -1 Select a suitable laser source, set the integration time to 10 seconds, and start spectral collection. The software will automatically record the scattered light. After the integration time is complete, the software will generate a spectrum, such as the Raman spectrum shown below. Figure 2 As shown.

[0108] from Figure 2 As can be seen from the Raman spectrum of PEDOT-coated manganese dioxide nanowires, both the Mn-O characteristic peaks of manganese dioxide and the C, Cα=Cβ, and C=C characteristic peaks of PEDOT are present. This indicates that PEDOT was successfully coated on the surface of manganese dioxide nanowires, and further proves that the in-situ coating of PEDOT initiated by manganese dioxide does not damage the structure of manganese dioxide nanowires.

[0109] 4. Electron paramagnetic resonance (EPR) spectra of manganese dioxide nanowires and PEDOT-coated manganese dioxide nanowires from Example 5 were obtained using paramagnetic resonance (EPR) technology. The specific method was as follows: the ESR spectrometer was turned on, the control software was started, the sample was loaded into the ESR sample tube, and the sample tube was placed in the sample chamber in a magnetic field. The microwave frequency was set, typically in the range of 9-10 GHz. The magnetic field range was set, typically between 0.3-1.0 T (Tesla). A magnetic field scan was started, and the magnetic field was gradually increased or decreased, recording the microwave absorption under different magnetic fields. The instrument recorded the relationship between microwave absorption and the magnetic field, forming an ESR spectrum. The results are shown below. Figure 3 As shown.

[0110] from Figure 3As can be seen from the EPR spectrum of PEDOT-coated manganese dioxide nanowires, a significant signal is observed at g=2.003, while the EPR spectrum of manganese dioxide nanowires shows no signal peak. The presence of the signal peak indicates the presence of oxygen vacancies in the PEDOT-coated manganese dioxide nanowires. The introduction of oxygen vacancies can improve electron transport in the conductive polymer-coated manganese dioxide nanowires. Based on the improved conductivity of the conductive polymer, the conductivity of the polymer-coated manganese dioxide nanowires is further enhanced, thereby improving the rate performance of the polymer-coated manganese dioxide nanowires.

[0111] Comparative Example 1

[0112] A method for preparing a button cell battery differs from Example 5 in that the manganese dioxide nanowires are not coated with conductive polymer monomers, and the prepared manganese dioxide nanowires are directly used as active materials to prepare the positive electrode of a zinc-ion battery.

[0113] Comparative Example 2

[0114] A method for preparing a button cell differs from Example 5 in that an external oxidant is added to initiate the in-situ coating of conductive polymer with manganese dioxide nanowires. In the step of preparing conductive polymer-coated manganese dioxide nanowires, 0.5g of 3,4-ethylenedioxythiophene monomer is added along with 2.0g of ferric chloride oxidant. The mixture is ultrasonically dispersed and stirred at high speed. After polymerization for 12 hours, the mixture is centrifuged and freeze-dried.

[0115] Comparative Example 3

[0116] A method for preparing a button cell differs from Example 5 in that, in the step of coating manganese dioxide nanowires with conductive polymer, the mass of the conductive polymer monomer 3,4-ethylenedioxythiophene monomer is 1g, and the mass of the manganese dioxide nanowires is 10g.

[0117] Comparative Example 4

[0118] A method for preparing a button cell battery differs from Example 5 in that, in the step of preparing conductive polymer-coated manganese dioxide nanowires, the pH is adjusted to be greater than 4.

[0119] Comparative Example 5

[0120] A method for preparing a button cell differs from Example 5 in that, in the step of preparing manganese dioxide nanowires, 10 mmol of ammonium sulfate, 10 mmol of manganese sulfate, and 10 mmol of persulfate are added to 200 mL of deionized water, stirred until completely dissolved, and then transferred to a high-temperature reactor. The hydrothermal reaction is carried out at 180°C for 24 h, while the reaction solution is magnetically stirred. After the reaction is completed, the solution is centrifuged, dried, and manganese dioxide nanowires are obtained.

[0121] Comparative Example 6

[0122] A method for preparing a button cell differs from Example 5 in that, in the step of preparing manganese dioxide nanowires, 20 mmol of ammonium sulfate, 5 mmol of manganese sulfate, and 5 mmol of ammonium persulfate are added to 200 mL of deionized water, stirred until completely dissolved, and then transferred to a high-temperature reactor. The hydrothermal reaction is carried out at 120°C for 24 h, while the reaction solution is magnetically stirred. After the reaction is completed, the solution is centrifuged, dried, and manganese dioxide nanowires are obtained.

[0123] 1. Using the same method as in the examples, the specific capacity of the button batteries prepared in Comparative Examples 1-6 was tested at a current density of 0.1 A / g; the rate performance was tested at a current density of 5.0 A / g; and the cycle performance was tested at a current density of 0.4 A / g. The capacity retention rate of the battery was detected after 500 cycles.

[0124] The test results are as follows:

[0125]

[0126] In Comparative Example 1, the manganese dioxide nanowires were not coated with conductive polymer monomers. The prepared manganese dioxide nanowires were directly used as the active material to prepare the positive electrode of the zinc-ion battery. The resulting button battery showed a significant decrease in specific capacity and capacity retention at different current densities compared to the button battery prepared in Example 5. This may be because the prepared manganese dioxide nanowires were directly used as the active material to prepare the positive electrode of the zinc-ion battery, and no conductive coating layer was formed on the surface of the manganese dioxide nanowires, resulting in poor conductivity.

[0127] In Comparative Example 2, the conductive polymer-coated manganese dioxide nanowires prepared by adding an additional 2.0g of ferric chloride as an oxidant resulted in button batteries with significantly lower specific capacity and capacity retention at different current densities compared to the button batteries in Example 5. This demonstrates that the present invention can form a conformal coating layer on the surface of manganese dioxide nanowires in a one-step process, reducing the products of conductive polymer self-polymerization. The conformal coating layer has a stronger bonding force with the manganese dioxide nanowires. Manganese dioxide itself acts as a self-initiating oxidant without the need for additional oxidants, resulting in mild reaction conditions that preserve the initial nanowire morphology of the manganese dioxide nanowires. The coated conductive polymer layer can effectively stabilize the structure of the manganese dioxide nanowires, thereby ensuring the conductivity of the inner manganese dioxide nanowires and improving the cycle stability of the polymer-coated manganese dioxide nanowires.

[0128] The conductive polymer-coated manganese dioxide nanowires prepared in Comparative Example 3, when used to assemble a coin cell, exhibited lower specific capacity and capacity retention than the coin cell in Example 5 at different current densities. This demonstrates that when using conductive polymer-coated manganese dioxide nanowires, a low polymer monomer content has limited effect on improving conductivity. Furthermore, as the polymer monomer content gradually increases, conductivity initially increases and then decreases. Excessively high polymer monomer content not only leads to increased costs but also causes conductivity to decrease when the ratio of polymer monomers to manganese dioxide nanowires exceeds 1:1.

[0129] In Comparative Example 4, the pH value in the manganese dioxide nanowire preparation step was greater than 4. The resulting conductive polymer-coated manganese dioxide nanowires were used to assemble a button battery. However, the specific capacity and capacity retention rate of the button battery in Example 5 were not as good as those in Example 5 at different current densities. The capacity retention rate was significantly lower than that in Example 5. This shows that the pH value in the manganese dioxide nanowire preparation step has a significant impact on the reaction results. Both excessively high and excessively low pH values ​​are not conducive to the formation of a stable polymer coating layer on the surface of manganese dioxide nanowires.

[0130] In Comparative Example 5, the ratio of ammonium sulfate, manganese sulfate, and ammonium persulfate in the preparation of manganese dioxide nanowires was 1:1:1. The resulting conductive polymer-coated manganese dioxide nanowires were used to assemble button batteries. However, the specific capacity and capacity retention of the button batteries were not as good as those in Example 5 at different current densities. This may be because the ratio of ammonium sulfate, manganese sulfate, and ammonium persulfate affects the structure of the generated manganese dioxide nanowires, resulting in differences in the conductivity of the manganese dioxide nanowires.

[0131] In Comparative Example 6, the manganese dioxide nanowires were prepared by hydrothermal reaction at 120°C for 24 hours. The resulting conductive polymer-coated manganese dioxide nanowires were used to assemble a button battery. The specific capacity and capacity retention of the button battery were not as good as those in Example 5 at different current densities. This shows that the hydrothermal reaction temperature has a significant impact on the structure of manganese dioxide nanowires, which can also lead to differences in the conductivity of manganese dioxide nanowires.

[0132] 2. Obtain the rate performance curves of the button batteries prepared in Example 5 and Comparative Example 1 at different current densities. Specifically, the button batteries from Example 5 and Comparative Example 1 were clamped onto a Xinwei battery tester. After confirming the batteries were functioning normally without short circuits, parameters were set on the BTS client on the control computer. The set parameters included the mass of the active material, the test current densities (0.1, 0.2, 0.4, 0.8, 1.0, 1.5, 2.0, 3.0, 5.0 A / g), the charging cut-off voltage (1.8V), the discharging cut-off voltage (0.8V), and 5 cycles at different current densities. The specific capacity, voltage, and other data for each cycle were recorded. The data was exported and plotted using ORIGIN. The results are shown below. Figure 4 As shown.

[0133] from Figure 4 As can be seen from Example 5, the rate performance of the battery made with PEDOT-coated manganese dioxide nanowires is better than that of the button battery made with manganese dioxide nanowires directly as the positive electrode material in Comparative Example 1.

[0134] 3. Obtain the cycle performance curves of the button batteries prepared in Example 5 and Comparative Example 1 after 500 cycles at a current density of 0.4 A / g. Specifically, the button batteries were clamped onto a Xinwei battery tester. After confirming the batteries were functioning normally without short circuits, parameters were set on the BTS client on the control computer. The set parameters included the mass of the active material, the test current density of 0.4 A / g, the charging cut-off voltage of 1.8 V, the discharging cut-off voltage of 0.8 V, and the number of cycles (500). The specific capacity of each cycle was recorded. After the test, the data was exported and plotted using ORIGIN. The results are shown below. Figure 5 As shown.

[0135] from Figure 5 As can be seen from Example 5, the cycle stability of the battery made with PEDOT-coated manganese dioxide is better than that of the battery made with manganese dioxide nanowires directly as the positive electrode in Comparative Example 1.

[0136] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for preparing a battery cathode material, characterized by, The method comprises the following steps: The manganese dioxide nanowire is added into a dispersion solvent, a pH range is adjusted, a polymer monomer is mixed, and a polymerization reaction is performed to obtain a conductive polymer coated manganese dioxide nanowire; the pH range is 2.5-4.5; the mixing mass ratio of the manganese dioxide nanowire to the polymer monomer is 0.5-2.5:1; the polymer monomer is a 3,4-ethylenedioxythiophene monomer; the manganese dioxide nanowire is prepared by hydrothermal reaction of ammonium sulfate, manganese sulfate and ammonium persulfate; the molar ratio of the ammonium sulfate, the manganese sulfate and the ammonium persulfate is 3-5:0.5-1.5:1; the temperature of the hydrothermal reaction is 150-200 DEG C, and the time of the hydrothermal reaction is 20-30 h.

2. The production method according to claim 1, wherein The pH range is 3-4.

3. The production method according to claim 1, wherein The mixing mass ratio of the manganese dioxide nanowire to the polymer monomer is 1-2:

1.

4. A cathode material for a battery produced by the method of any one of claims 1 to 3, characterized in that, The battery anode material comprises manganese dioxide nanowires and a conductive polymer coated on the surface of the manganese dioxide nanowires.

5. The battery cathode material of claim 4, wherein, The battery anode material has oxygen vacancies.

6. A battery, characterized by The battery anode material is prepared by the preparation method in any one of claims 1-3.

7. The method for preparing the battery as described in claim 6, characterized in that, The method comprises the following steps: S1, preparing a battery anode: the battery anode material in any one of claims 4-5 or the anode material prepared by the preparation method in any one of claims 1-3 is added into N-methylpyrrolidone to mix into a uniform slurry, the slurry is coated on a titanium foil to prepare a zinc ion battery anode; the solid content of the slurry is 55%-60%; S2, preparing a battery: a metal zinc sheet is used as a negative electrode, glass fiber is used as a separator, and zinc sulfate is used as an electrolyte to assemble a button cell; the mass ratio of the anode material, acetylene black and polyvinylidene fluoride is 5-10:0.5-2:1.

Images