WO2023088412A1

WO2023088412A1 - Positive electrode material, and preparation method therefor and application thereof

Info

Publication number: WO2023088412A1
Application number: PCT/CN2022/132790
Authority: WO
Inventors: 傅洋; 陈璞
Original assignee: 瑞海泊(常州)能源科技有限公司
Priority date: 2021-11-18
Filing date: 2022-11-18
Publication date: 2023-05-25
Also published as: CN116137321A

Abstract

A positive electrode material, and a preparation method therefor and an application thereof. The method comprises the following steps: (1) mixing electrolytic manganese dioxide, a conductive agent, a polymer, an oxide, and a grinding ball, and then performing sanding; (2) performing spray drying on a sanded mixture; and under a protective atmosphere, sintering a product obtained in step (2) so as to obtain a positive electrode material.

Description

Positive electrode material and its preparation method and application

priority information

This disclosure requests the priority of the Chinese patent application with the patent application number 202111368709.3 and the application title "cathode material and its preparation method and application" submitted to the State Intellectual Property Office of China on November 18, 2021, and its entire content is passed References are incorporated in this disclosure.

technical field

The disclosure belongs to the technical field of batteries, and in particular relates to a positive electrode material and a preparation method and application thereof.

Background technique

With the excessive exploitation and utilization of oil, coal, natural gas and other resources, it has led to the depletion of non-renewable resources and environmental pollution. Energy and the environment have become difficult problems hindering the sustainable development of the world today. Therefore, it is particularly urgent to look for green energy to replace traditional fossil fuels and to seek the harmonious development of people and the environment. Zinc-ion batteries have attracted extensive attention because of their divalent metals can increase the discharge specific capacity of the battery system, and also because of their advantages such as small volume, low cost, aqueous electrolyte, green and pollution-free. Zinc ion battery is composed of positive electrode, negative electrode, electrolyte and separator. The positive electrode is an active material that can embed zinc ions. The negative electrode is zinc sheet or zinc powder. The electrolyte is mainly water-based electrolyte. short circuit due to contact.

As a cathode material for zinc-ion batteries, MnO ₂ has the characteristics of high power density and high energy density, and the Coulombic efficiency is close to 100%. In addition, manganese is abundant in natural reserves and is environmentally friendly, so it has great potential as a cathode material for zinc-ion batteries. However, _MnO2 has poor electronic conductivity and the dissolution of manganese ions during charging and discharging, which hinders its practical application in ion batteries. At the same time, the hydrogen evolution reaction at the negative electrode will lead to instability of the battery system and affect battery life.

Therefore, the existing cathode materials for zinc-ion batteries need to be improved.

public content

The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent. Therefore, an object of the present disclosure is to propose a positive electrode material and its preparation method and application. The positive electrode material prepared by this method can inhibit the dissolution of active materials during charging and discharging, improve the utilization rate of active materials, and effectively inhibit The hydrogen evolution reaction of the negative electrode delays or prevents the capacity decay during the cycle to a certain extent, and its application to the aqueous zinc-manganese battery can improve the stability, rate performance, cycle life and safety of the aqueous zinc-manganese battery.

In one aspect of the present disclosure, the present disclosure proposes a method for preparing a cathode material. According to an embodiment of the present disclosure, the method includes:

(1) Sand milling after electrolytic manganese dioxide, conductive agent, polymer, oxide and grinding balls are mixed;

(2) The mixture after sanding is spray-dried;

(3) Sintering the product obtained in step (2) under a protective atmosphere, so as to obtain a positive electrode material.

According to the method for preparing the positive electrode material in the embodiment of the present disclosure, the electrolytic manganese dioxide, the conductive agent, the polymer, the oxide and the grinding ball are mixed and sand-milled, and the particle size of the electrolytic manganese dioxide after sand-milling can reach several Ten nanometers, the added conductive agent can have uniform and sufficient contact with the primary particles of electrolytic manganese dioxide after sanding, thereby improving the electronic conductivity of electrolytic manganese dioxide. The addition of polymer, on the one hand, can improve the binding force of the secondary particles, so that the pelleting rate of the particles is better, on the other hand, it can inhibit the dissolution of manganese ions in the process of charging and discharging the active material electrolytic manganese dioxide, and improve the utilization of the active material Rate. The addition of oxides can effectively inhibit the hydrogen evolution reaction of the negative electrode, and to some extent delay or prevent the capacity decay during the cycle. Then, the sand-milled mixture is spray-dried and then sintered to obtain the positive electrode material. Therefore, the positive electrode material prepared by this method can inhibit the dissolution of the active material during the charging and discharging process, improve the utilization rate of the active material, and effectively inhibit the hydrogen evolution reaction of the negative electrode, and delay or prevent the capacity attenuation during the cycle process to a certain extent. Applying it to the aqueous zinc-manganese battery can improve the stability, rate performance, cycle life and safety of the aqueous zinc-manganese battery.

In addition, the method for preparing positive electrode materials according to the above-mentioned embodiments of the present disclosure may also have the following additional technical features:

In some embodiments of the present disclosure, the mass ratio of the total mass of the electrolytic manganese dioxide, the conductive agent, the polymer to the oxide, and the grinding ball is (0.01-20):1, and the The sanding speed is 1000~3000r/min, and the time is 0.5~2h. Thereby, the elution of the active material during the charge and discharge process can be suppressed, the utilization rate of the active material can be improved, and the hydrogen evolution reaction of the negative electrode can be effectively suppressed.

In some embodiments of the present disclosure, in step (1), the mass ratio of the electrolytic manganese dioxide, the conductive agent, the polymer and the oxide is 100:(0-5):( 0~3): (0~3). Thereby, the elution of the active material during the charge and discharge process can be suppressed, the utilization rate of the active material can be improved, and the hydrogen evolution reaction of the negative electrode can be effectively suppressed.

In some embodiments of the present disclosure, the conductive agent includes at least one of CNT, AB, SP, KS-6, KS-15 and graphene.

In some embodiments of the present disclosure, the polymer includes at least one of gelatin, PAA, PVA, PSS, PTFE, and PAM.

In some embodiments of the present disclosure, the oxide includes at least one of Bi ₂ O ₃ , MgO, SiO ₂ and ZrO ₂ .

In some embodiments of the present disclosure, in step (1), the electrolytic manganese dioxide, the conductive agent, the polymer, the oxide, the additive and the ball are mixed, wherein the The additives include at least one of bismuth nitrate, ammonium fluoride, sodium fluoride, aluminum sulfate, titanium sulfate and zirconium sulfate. Thus, the dissolution of manganese ions can be effectively suppressed, and the cycle performance of the battery cell can be improved.

In some embodiments of the present disclosure, the mass ratio of the electrolytic manganese dioxide to the additive is 100:(0-20).

In some embodiments of the present disclosure, in step (2), the inlet air temperature of the spray drying is 150°C-300°C, the outlet air temperature is 100-200°C, and the air volume is 0-30L/min. Thereby, the elution of the active material during the charge and discharge process can be suppressed, the utilization rate of the active material can be improved, and the hydrogen evolution reaction of the negative electrode can be effectively suppressed.

In some embodiments of the present disclosure, in step (3), the sintering temperature is 100-400° C., and the holding time is 0.1-20 h. Thereby, the elution of the active material during the charge and discharge process can be suppressed, the utilization rate of the active material can be improved, and the hydrogen evolution reaction of the negative electrode can be effectively suppressed.

In a second aspect of the present disclosure, the present disclosure provides a positive electrode material. According to an embodiment of the present disclosure, the positive electrode material is prepared by the above method. Therefore, the positive electrode material can inhibit the dissolution of the active material during the charge and discharge process, improve the utilization rate of the active material, and effectively inhibit the hydrogen evolution reaction of the negative electrode, and delay or prevent the capacity decay during the cycle process to a certain extent.

In a third aspect of the present disclosure, the present disclosure provides an aqueous zinc-manganese battery. According to an embodiment of the present disclosure, the aqueous zinc-manganese battery includes a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode is prepared by using the above-mentioned positive electrode material. Thus, the stability, rate performance, cycle life and safety of the aqueous zinc-manganese battery are improved.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

Description of drawings

The above and/or additional aspects and advantages of the present disclosure will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, in which:

1 is a schematic flow diagram of a method for preparing a positive electrode material according to an embodiment of the present disclosure;

Fig. 2 is the SEM picture of the positive electrode material in embodiment 1;

Fig. 3 is the SEM picture of the positive electrode material in embodiment 1;

Fig. 4 is the electrical performance curve diagram of the aqueous zinc-manganese battery in embodiment 1;

Fig. 5 is the electrical performance curve diagram of the aqueous zinc-manganese battery in embodiment 2;

Fig. 6 is the electrical performance curve diagram of the aqueous zinc-manganese battery in embodiment 3;

Fig. 7 is the electrical performance curve diagram of the aqueous zinc-manganese battery in embodiment 4;

FIG. 8 is a graph showing electrical performance of the aqueous zinc-manganese battery in Example 5. FIG.

Detailed ways

The embodiments described below by referring to the figures are exemplary and are intended to explain the present disclosure and should not be construed as limiting the present disclosure.

In one aspect of the present disclosure, the present disclosure proposes a method for preparing a cathode material. According to an embodiment of the present disclosure, referring to FIG. 1 , the method includes:

S100: Sanding after mixing electrolytic manganese dioxide, conductive agent, polymer, oxide and grinding balls

In this step, the electrolytic manganese dioxide, conductive agent, polymer, oxide and grinding balls are mixed and then sand-milled. After sand-milling, the particle size of electrolytic manganese dioxide can reach tens of nanometers. The mill can have uniform and sufficient contact with the primary particles of electrolytic manganese dioxide, thereby improving the electronic conductivity of electrolytic manganese dioxide. The added polymer, on the one hand, can improve the binding force of the secondary particles, so that the particles have a better spherical rate; In the electrolyte, it can inhibit the dissolution of manganese ions in the active material electrolytic manganese dioxide during charging and discharging, and improve the utilization rate of the active material. The added oxide can inhibit the dissolution and deposition reaction of manganese ions, thereby reducing the pH in the electrolyte. fluctuations, reducing the corrosion of the negative electrode, thereby effectively inhibiting the hydrogen evolution reaction of the negative electrode, and delaying or preventing the capacity decay during the cycle to a certain extent.

It should be noted that the specific types of the above-mentioned conductive agents, polymers and oxides are not particularly limited, and those skilled in the art can select according to actual needs. For example, conductive agents include but are not limited to CNT (carbon nanotubes), AB At least one of (acetylene black), SP (conductive carbon black), KS-6 (conductive graphite), KS-15 (conductive graphite) and graphene, polymers include but not limited to gelatin, PAA (polyacrylic acid), At least one of PVA (polyvinyl alcohol), PSS (sodium polystyrene sulfonate), PTFE (polytetrafluoroethylene) and PAM (polyacrylamide), oxides include but not limited to Bi ₂ O ₃ , MgO, At least one of SiO ₂ and ZrO ₂ .

Further, the mass ratio of the total mass of the electrolytic manganese dioxide, conductive agent, polymer and oxide to the grinding ball is (0.01-20):1. The inventors found that if the mass ratio of the total mass of electrolytic manganese dioxide, conductive agent, polymer and oxide to the mass of the grinding ball is too high, the sanding of the material will not be sufficient, and the particle size of the material cannot be greatly reduced, which will lead to the spraying process. A good spherical material cannot be formed; if the mass ratio of the total mass of electrolytic manganese dioxide, conductive agent, polymer and oxide to the mass of the grinding ball is too low, the yield of the material will be reduced, and a large amount of material will remain in the sanding chamber middle.

Further, the sanding speed is 1000-3000r/min, and the time is 0.5-2h. Preferably, the sanding speed is 2500r/min, and the sanding time is 1h. The inventors have found that if the rotational speed of the sand mill is too high, the crystal lattice of the material will be destroyed, which will cause the phase transition of the material, and will have a negative impact on the added polymer, causing the polymer polymer chain to be destroyed; if the sand mill If the rotational speed is too low, the particle size of the material cannot be greatly reduced, and the sanding effect cannot be achieved; if the sanding time is too long, the synthesis efficiency of the material will be reduced, and the crystal lattice of the material will be destroyed to a certain extent. A certain degree of phase change is caused. If the sanding time is too short, the material will not be fully sanded, and the particle size distribution of the material will not be concentrated, which will have a negative impact on the later balling of the material.

Further, the mass ratio of the electrolytic manganese dioxide, conductive agent, polymer and oxide is 100: (0-5): (0-3): (0-3), preferably electrolytic manganese dioxide, conductive agent, The mass ratio of the polymer to the oxide is 100:(0.1-5):(0.01-3):(0.01-3). The inventors have found that if too little electrolytic manganese dioxide is added, the energy density of the cell will be reduced, and the cost will increase; if too much conductive agent is added, the cost of the material will be increased, and the energy density of the cell will be reduced. Too much polymer or oxide will reduce the conductivity of the material and affect the performance of the gram capacity.

Further, in this step, electrolytic manganese dioxide, conductive agent, polymer, oxide, additives and grinding balls are mixed, wherein the additives include bismuth nitrate, ammonium fluoride, sodium fluoride, aluminum sulfate, titanium sulfate and at least one of zirconium sulfate. The inventors found that by adding additives to the material, the corresponding ions (Bi ³⁺ , F ^- , Al ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ ) can be doped into MnO ₂ , thereby suppressing the dissolution of manganese ions, Improve the cycle performance of the cell; at the same time, the mass ratio of the electrolytic manganese dioxide to the additive is 100:(0-20), preferably 100:(0-5). The inventors have found that if the mass ratio of electrolytic manganese dioxide to additives is too high, it will be difficult to suppress the dissolution reaction of manganese ions, which is not conducive to the improvement of battery cycle performance; if the mass ratio of electrolytic manganese dioxide to additives is too low, it will lead to The activity of the material is reduced, which limits the gram capacity of the material and increases the cost.

S200: Spray drying the sanded mixture

In this step, the sand-milled mixture obtained above is spray-dried, specifically, the air inlet temperature of the above-mentioned spray drying is 150°C-300°C, the air outlet temperature is 100-200°C, and the air volume is 0-30L/min , preferably, the air volume is 20L/min. The inventors found that if the air inlet temperature is too high, the material will be looser, and the hollow ball phenomenon will easily appear; if the air inlet temperature is too low, there will be too much residual moisture in the material; Loose, prone to hollow ball phenomenon, if the air outlet temperature is too low, it will cause too much residual moisture in the material.

S300: Sintering the product obtained in step S200 under a protective atmosphere

In this step, the product obtained in the above step S200 is sintered under a protective atmosphere. Through sintering, the residual moisture in the product obtained in step S200 can be further reduced, and the binding force of the primary particles can be improved, thereby making the positive electrode material sphericity Keep it better.

Further, the sintering temperature is 100-400°C, and the holding time is 0.1-20h. The inventors have found that if the sintering temperature is too high, the phase transition of the material will be caused, and if the sintering temperature is too low, the binding force of the primary particles will be low and the sphericity cannot be maintained.

In a second aspect of the present disclosure, the present disclosure provides a positive electrode material. According to an embodiment of the present disclosure, the positive electrode material is prepared by the above method. Therefore, the positive electrode material can inhibit the dissolution of the active material during the charge and discharge process, improve the utilization rate of the active material, and effectively inhibit the hydrogen evolution reaction of the negative electrode, and delay or prevent the capacity decay during the cycle process to a certain extent. It should be noted that the features and advantages described above with respect to the method for preparing the positive electrode material are also applicable to the positive electrode material, and will not be repeated here.

In a third aspect of the present disclosure, the present disclosure provides an aqueous zinc-manganese battery. According to an embodiment of the present disclosure, the aqueous zinc-manganese battery includes a positive electrode, a negative electrode, an electrolyte and a separator, wherein the positive electrode is prepared by using the above-mentioned positive electrode material. Thus, the stability, rate performance, cycle life and safety of the aqueous zinc-manganese battery are improved.

It should be noted that the above-mentioned positive electrode is a positive electrode sheet made of the positive electrode material as the active material. Specifically, the positive electrode material, acetylene black, sodium hydroxymethyl cellulose and acrylate polymer are in a mass ratio of 80:15:2: 3 After mixing, add water and stir to form a slurry, and then attach the slurry to the positive electrode current collector by coating or pulling the slurry to obtain the positive electrode sheet.

It should be noted that the specific types of the above-mentioned negative electrode and separator are not particularly limited, and those skilled in the art can choose according to actual needs. For example, the negative electrode includes but is not limited to at least one of zinc and zinc alloys, and the zinc alloy can be Zinc-nickel alloy, zinc-tin alloy, zinc-antimony alloy or zinc-bismuth alloy, etc., and the negative electrode can be a pole piece made of zinc foil or zinc powder through drawing process; the diaphragm includes but not limited to glass fiber, dust-free paper, dialysis membrane , at least one of non-woven fabrics and cellulose films.

Further, the electrolytic solution is a mixture of zinc salt and manganese salt, and the concentration of the zinc salt is 0.5-2.0 mol/L, and the concentration of the manganese salt is 0.1-1.0 mol/L. The inventors have found that if the concentration of the zinc salt is too high, the ionic conductivity of the electrolyte will decrease, and the polarization of the cell will increase; if the concentration of the zinc salt is too low, the electrical performance of the cell will be reduced. If the manganese salt If the concentration of manganese salt is too high, the ionic conductivity of the electrolyte will decrease, and the polarization of the cell will increase. If the concentration of manganese salt is too low, the electrical performance of the cell will be reduced. Specifically, the zinc salt can be at least one of zinc sulfate, zinc nitrate, zinc chloride and zinc trifluoromethanesulfonate, and the manganese salt can be at least one of manganese sulfate, manganese nitrate, manganese chloride and manganese trifluoromethanesulfonate. at least one of the .

It should be noted that the features and advantages described above for the method for preparing the positive electrode material are also applicable to the aqueous zinc-manganese battery, and will not be repeated here.

The present disclosure will be described below with reference to specific embodiments. It should be noted that these embodiments are only illustrative and do not limit the present disclosure in any way. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

Example 1

Preparation of cathode material

(1) Mix 97wt% electrolytic manganese dioxide, 3wt% CNT, and grinding balls according to the ball-to-material ratio of 2:1, and then perform sanding. The sanding speed is 2500r/min, and the sanding time is 1h.

(2) Spray-dry the sand-milled mixture. The inlet air temperature for spray drying is 180° C., the outlet air temperature is 120° C., and the air volume is 20 L/min.

(3) The product obtained in step (2) is sintered under an argon protective atmosphere, the sintering temperature is 200°C, and the holding time is 4h, the positive electrode material can be obtained. 2, it can be seen that the particle size of the positive electrode material particles prepared by it is about 10 μm, and the particle shape is spherical particles; it can be seen from Figure 3 that the positive electrode material is a composite material of electrolytic manganese dioxide and CNT, and electrolytic manganese dioxide and The CNTs are evenly dispersed, and the two build a conductive network, thereby improving the conductivity of the positive electrode material and increasing the activity and utilization of the positive electrode material.

Preparation of the positive electrode sheet: mix the positive electrode material, acetylene black, sodium hydroxymethyl cellulose and acrylate polymer according to the mass ratio of 80:15:2:3, add water and stir to form a slurry, and then pass the slurry through drawing Attached to the positive electrode current collector in the same way, the positive electrode sheet can be obtained.

The positive pole piece is used as the positive pole, and the pole piece made of zinc-bismuth alloy drawn on copper mesh is used as the negative pole. The separator is glass fiber, and the electrolyte is zinc sulfate and manganese sulfate. The concentration of manganese is 0.4mol/L.

Assemble the battery and perform electrochemical performance test. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 200mAh/g, and the stable gram capacity is 195mAh/g after 5 cycles, and the gram capacity has almost no decay after 100 cycles, the capacity retention rate is 97%, and the average Coulombic efficiency is 99.43 %. The electrical performance data of the battery is shown in Figure 4.

Example 2

3wt% CNT was replaced by a mixture of 1%wtCNT, 1%wtSP and 1wt% graphene, and the rest of the process was the same as in Example 1.

Assemble the battery and perform electrochemical performance test. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of the test data results: the first 5 laps of the gram capacity is up to 190mAh/g, after 5 laps, the gram capacity has a long period of slow rise, and after 50 laps, the gram capacity tends to be stable, maintaining at 220mAh/g, and the cycle reaches 100 laps There is no capacity fading, and the average Coulombic efficiency is 99.36%. The electrical performance data of the battery is shown in Figure 5.

Example 3

Preparation of cathode material

(1) Mix 95wt% electrolytic manganese dioxide, 3wt% CNT, 2wt% gelatin, and grinding balls according to the ball-to-material ratio of 2:1, and then perform sanding. The sanding speed is 2500r/min, and the sanding time is 1h.

(3) The product obtained in step (2) is sintered under an argon protective atmosphere at a temperature of 200° C. and a holding time of 4 hours to obtain the positive electrode material.

The positive pole piece is used as the positive pole, the pole piece made of zinc-bismuth alloy drawn on copper mesh is used as the negative pole, the separator is glass fiber, the electrolyte is zinc sulfate and manganese sulfate, the concentration of zinc sulfate is 1.0mol/L, the concentration of manganese It is 0.4mol/L.

Assemble the battery and perform electrochemical performance test. The test conditions are: constant current charge and discharge, the voltage range is 1.0-1.9V, the current density is 50mA/g in the first 5 cycles, and the current density is 125mA/g after 5 cycles. Analysis of the test data results: the first 5 cycles of the gram capacity showed a maximum of 175mAh/g, and after 5 cycles, the gram capacity slowly rose and tended to be stable, maintaining at 185mAh/g, and the gram capacity did not show a large decline after 100 cycles, and the capacity retention rate was 94.59% , with an average Coulombic efficiency of 99.21%. The electrical performance data of the battery is shown in Figure 6.

Example 4

2wt% gelatin was replaced by 0.2wt% PAA, and the rest of the process was the same as in Example 3.

Assemble the battery and perform electrochemical performance test. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the initial gram capacity is low, the first 10 cycles of gram capacity is in a rapid rising stage, the 10th cycle of gram capacity can reach 150mAh/g, and the gram capacity after 10 cycles tends to be stable and gradually maintains at around 185mAh/g , there is no significant attenuation after 100 cycles, the capacity retention rate is 97.29%, and the average Coulombic efficiency is 99.54%. The electrical performance data are shown in Figure 7.

Example 5

Preparation of cathode material

(1) After mixing 95wt% electrolytic manganese dioxide, 3wt% CNT, 2wt% _Bi2O3 and grinding balls according to the ball-to-material ratio of 2: ₁ , carry out sand milling, the speed of sand milling is 2500r/min, the time of sand milling for 1h.

Assemble the battery and perform electrochemical performance test. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 180mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 175mAh/g. There is no obvious decline in gram capacity after 120 cycles, the capacity retention rate is 94.28%, and the average coulomb The efficiency is 99.56%. The electrical performance data are shown in Figure 8.

Example 6

After mixing 95wt% electrolytic manganese dioxide, 2wt% CNT, 2wt% gelatin and 1wt% _Bi2O3 and grinding balls according to the ball-to-material ratio of 2: ₁ , sand milling is carried out, and the speed of sand milling is 2500r/min. Time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, the voltage range is 1.0-1.9V, the current density is 50mA/g for the first 5 cycles, and the current density is 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 190mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 178mAh/g. After 120 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 92%, and the average coulomb The efficiency is 99.52%.

Example 7

Mix 93wt% electrolytic manganese dioxide, 4wt% AB, 2wt% PAA and 1wt% MgO with grinding balls according to the ball-to-material ratio of 2:1 and perform sanding. The speed of sanding is 2500r/min, and the time of sanding is 1h , all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 193mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 181mAh/g. After 120 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 91%, and the average coulomb The efficiency is 99.41%.

Example 8

93wt% electrolytic manganese dioxide, 4wt% SP, 2wt% PVA and 1wt% SiO ₂ and grinding balls are mixed according to the ball-to-material ratio of 2:1 and sand milled. The speed of sand milling is 2500r/min, and the time of sand milling is 1h, the rest are the same as in Example 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 195mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 173mAh/g. There is no obvious decline in gram capacity after 120 cycles, the capacity retention rate is 90%, and the average coulomb The efficiency is 99.4%.

Example 9

93wt% electrolytic manganese dioxide, 4wt% KS-6, 2wt% PSS and 1wt% ZrO ₂ and grinding balls are mixed according to the ball-to-material ratio of 2:1 and sand milled. The speed of sand milling is 2500r/min. Time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 186mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 171mAh/g. There is no obvious decline in gram capacity after 120 cycles, the capacity retention rate is 92%, and the average coulomb The efficiency is 99.43%.

Example 10

After mixing 93wt% electrolytic manganese dioxide, 4wt% graphene, 2wt% PAM and 1wt% MgO and grinding balls according to the ball-to-material ratio of 2:1, sand milling is carried out, the speed of sand milling is 2500r/min, and the time of sand milling is 1h, the rest are the same as in Example 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 196mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 182mAh/g. After 120 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 90%, and the average coulomb The efficiency is 99.44%.

Example 11

93wt% electrolytic manganese dioxide, 4wt% KS-15, 2wt% PTFE and 1wt% ZrO ₂ and grinding balls are mixed according to the ball-to-material ratio of 2:1 and sand milled. The speed of sand milling is 2500r/min. Time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 184mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 171mAh/g. The gram capacity does not show obvious decay after 120 cycles, the capacity retention rate is 90%, and the average coulomb The efficiency is 99.4%.

Example 12

After mixing 93wt% electrolytic manganese dioxide, 4wt% KS-15, 3wt% bismuth nitrate and grinding balls according to the ball-to-material ratio of 2:1, sand milling is carried out. The speed of sand milling is 2500r/min, and the time of sand milling is 1h. All the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 195mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 185mAh/g. After 100 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 95%, and the average coulomb The efficiency is 99.5%.

Example 13

Mix 97wt% electrolytic manganese dioxide, 2wt% PSS, 1wt% bismuth nitrate, and grinding balls according to the ball-to-material ratio of 2:1 and then sand mill. The speed of sand milling is 2500r/min, and the time of sand milling is 1h. Example 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of the test data results: the highest gram capacity in the first 5 cycles is 150mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 134mAh/g. The gram capacity does not show obvious decay after 100 cycles, the capacity retention rate is 96%, and the average coulomb The efficiency is 99.7%.

Example 14

After mixing 93wt% electrolytic manganese dioxide, 1wt% PSS, 4wt% CNT, 2wt% bismuth nitrate and grinding balls according to the ball-to-material ratio of 2:1, sand milling is carried out. The speed of sand milling is 2500r/min, and the time of sand milling is 1h, the rest are the same as in Example 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of the test data results: the highest gram capacity in the first 5 cycles is 225mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 200mAh/g. The gram capacity does not show obvious decay after 120 cycles, the capacity retention rate is 95%, and the average coulomb The efficiency is 99.5%.

Example 15

Mix 93wt% electrolytic manganese dioxide, 1wt% PAA, 5wt% AB, 1wt% ammonium fluoride, and grinding balls according to the ball-to-material ratio of 2:1 and then sand mill. The sanding speed is 2500r/min, and the sanding time is Be 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of the test data results: the highest gram capacity in the first 5 cycles is 201mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 183mAh/g. There is no obvious decline in gram capacity after 100 cycles, the capacity retention rate is 94%, and the average coulomb The efficiency is 99.5%.

Example 16

Mix 93wt% electrolytic manganese dioxide, 1wt% PVA, 5wt% SP, 1wt% sodium fluoride and grinding balls according to the ball-to-material ratio of 2:1 and then perform sand milling. The speed of sand milling is 2500r/min. Be 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 210mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 185mAh/g. After 100 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 92%, and the average coulomb The efficiency is 99.4%.

Example 17

After mixing 93wt% electrolytic manganese dioxide, 0.5wt% PTFE, 5wt% graphene, 1.5wt% aluminum sulfate and grinding balls according to the ball-to-material ratio of 2:1, sand milling is carried out at a speed of 2500r/min. The time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 205mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 187mAh/g. There is no obvious decline in gram capacity after 100 cycles, the capacity retention rate is 91%, and the average coulomb The efficiency is 99.4%.

Example 18

After mixing 93wt% electrolytic manganese dioxide, 1wt% PAM, 5wt% KS-15, 1wt% titanium sulfate and grinding balls according to the ball-to-material ratio of 2:1, sand milling is carried out at a speed of 2500r/min. The time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 175mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 152mAh/g. There is no obvious decline in gram capacity after 100 cycles, the capacity retention rate is 92%, and the average coulomb The efficiency is 99.5%.

Example 19

93wt% electrolytic manganese dioxide, 1wt% gelatin, 4wt% KS-15, 2wt% zirconium sulfate and grinding balls were mixed according to the ball-to-material ratio of 2:1 and then sand milled. The speed of sand milling was 2500r/min. The time is 1h, all the other are with embodiment 5.

Perform electrochemical performance tests. The test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 185mAh/g, and the cycle capacity is relatively stable after 5 cycles, maintaining at 156mAh/g. After 120 cycles, the gram capacity has no obvious attenuation, the capacity retention rate is 93%, and the average coulomb The efficiency is 99.5%.

comparative example

Preparation of cathode material:

97wt% electrolytic manganese dioxide and 3wt% CNT were uniformly mixed without sand grinding and spray drying to obtain the positive electrode material.

Positive electrode sheet preparation and battery assembly: the process is the same as in Example 1.

Perform electrochemical performance tests. The battery test conditions are: constant current charge and discharge, voltage range 1.0-1.9V, current density 50mA/g for the first 5 cycles, and 125mA/g after 5 cycles. Analysis of test data results: the highest gram capacity in the first 5 cycles is 150mAh/g, after the current density is adjusted to 125mA/g, the gram capacity is 128mAh/g, and the gram capacity has a large decay after 100 cycles, and the capacity retention rate is 75%. Coulombic efficiency is 98%.

This shows that after the application mixes electrolytic manganese dioxide, conductive agent, polymer, oxide and grinding balls and carries out sand grinding and spray drying, manganese dioxide and conductive agent are mixed better, and the contact is more sufficient, forming a Three-dimensional conductive network, which is conducive to the development of the capacity of electrolytic manganese dioxide and the maintenance of electrical properties.

The embodiments of the present application have been described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Those of ordinary skill in the art will Under the inspiration of this application, without departing from the purpose of this application and the scope of protection of the claims, many forms can also be made, all of which belong to the protection of this application.

Claims

A method for preparing a positive electrode material, comprising:

(1) Sand milling after electrolytic manganese dioxide, conductive agent, polymer, oxide and grinding balls are mixed;

(2) The mixture after sanding is spray-dried;

(3) Sintering the product obtained in step (2) under a protective atmosphere, so as to obtain a positive electrode material.
The method according to claim 1, wherein, in step (1), the mass ratio of the total mass of the electrolytic manganese dioxide, the conductive agent, the polymer and the oxide and the grinding ball is ( 0.01～20): 1, the speed of the sand mill is 1000～3000r/min, and the time is 0.5～2h.
The method according to claim 1 or 2, wherein, in step (1), the mass ratio of the electrolytic manganese dioxide, the conductive agent, the polymer and the oxide is 100:(0～ 5): (0~3): (0~3).
The method according to any one of claims 1-3, wherein the conductive agent comprises at least one of CNT, AB, SP, KS-6, KS-15 and graphene.
The method according to any one of claims 1-4, wherein the polymer comprises at least one of gelatin, PAA, PVA, PSS, PTFE and PAM.
The method according to any one of claims 1-5, wherein the oxide comprises at least one of Bi2O3 , MgO , SiO2 and ZrO2 .
The method according to any one of claims 1-6, wherein, in step (1), the electrolytic manganese dioxide, the conductive agent, the polymer, the oxide, the additive and the The grinding balls are mixed, wherein the additive includes at least one of bismuth nitrate, ammonium fluoride, sodium fluoride, aluminum sulfate, titanium sulfate and zirconium sulfate.
The method according to any one of claims 1-7, wherein the mass ratio of the electrolytic manganese dioxide to the additive is 100:(0-20).
The method according to any one of claims 1-8, wherein, in step (2), the air inlet temperature of the spray drying is 150°C-300°C, the air outlet temperature is 100-200°C, and the air volume is 0～30L/min.
The method according to any one of claims 1-9, wherein, in step (3), the sintering temperature is 100-400°C, and the holding time is 0.1-20h.
A positive electrode material, wherein the positive electrode material is prepared by the method according to any one of claims 1-10.
An aqueous zinc-manganese battery comprising a positive pole, a negative pole, an electrolyte and a diaphragm, wherein the positive pole comprises the positive electrode material obtained by the method according to any one of claims 1-10 or the positive electrode material according to claim 11 .
The aqueous zinc-manganese battery according to claim 12, wherein the negative electrode comprises at least one of zinc and a zinc alloy.
The aqueous zinc-manganese battery according to claim 12 or 13, wherein the electrolyte is a mixture of zinc salt and manganese salt.
The aqueous zinc-manganese battery according to any one of claims 12-14, wherein the concentration of the zinc salt is 0.5-2.0 mol/L, and the concentration of the manganese salt is 0.1-1.0 mol/L.
The aqueous zinc-manganese battery according to any one of claims 12-15, wherein the separator comprises at least one of glass fiber, dust-free paper, dialysis membrane, non-woven fabric and cellulose membrane.