Potassium-doped chain-type trimanganese tetraoxide positive electrode material, and preparation method and application thereof

Abstract

The application discloses a kind of potassium-doped chain-like trimanganese tetroxide positive electrode materials and its preparation method and application, belong to the field of aqueous zinc-ion battery, preparation method includes: configuration isopropanol and deionized water mixed solution with a portion of.In magnetic stirring, manganese acetate, potassium chloride and nitrilotriacetic acid are dissolved into mixed solution, K-Mn-NTA, i.e.K-Mn-NCs precursor is prepared by hydrothermal method;Afterwards, K-Mn3O4-NCs is prepared by annealing method;Finally, polyaniline is in-situ polymerized on K-Mn3O4-NCs to obtain K-Mn3O4-NCs@PANI;The positive electrode material of the application is applied to zinc-ion battery, can improve the cycle performance and rate capability of zinc-ion battery, improve the conductivity of positive electrode material while inhibiting the dissolution of Mn, improve the electrochemical performance of zinc-ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aqueous zinc-ion batteries, and particularly relates to a potassium-doped chain trimanganese tetraoxide cathode material and a preparation method and application thereof. BACKGROUND

[0002] With the development of science and technology, the research and development of high-efficiency energy storage technology have attracted widespread attention. Compared with lithium-ion batteries which are expensive and have safety issues, aqueous zinc-ion batteries (AZIBs) are expected to become a substitute for lithium-ion batteries due to their abundant resources, environmental friendliness, low cost and high safety. Cathode materials are one of the important elements affecting the electrochemical performance of AZIBs. In recent years, many cathode materials have been developed, such as manganese-based oxides, vanadium-based oxides, polyanion compounds, quinone compounds and Prussian blue analogues. Manganese oxides have attracted widespread attention due to their abundant reserves, environmental friendliness, high discharge voltage and ease of synthesis. However, the practical application of these oxides in azib faces some challenges, such as dissolution problems during the cycling process, volume expansion, Zn 2+ slow reaction kinetics and poor intrinsic conductivity. These problems cause the capacity of aqueous zinc-ion batteries to decay during the cycling process, which seriously hinders the commercial development of aqueous zinc-ion batteries.

[0003] In order to overcome these obstacles and make manganese-based cathodes practical in AZIBs, researchers have explored various research strategies, including morphology / structure design, protective layer construction, defect engineering and ion / molecular pre-doping. The morphology / structure design strategy includes developing 2D structures and 3D structures of porous / hollow / hierarchical cathode nano / microstructures. These nanostructures have a large specific surface area and high conductivity, thereby increasing the contact area between the active material and the electrolyte. Therefore, the electronic conductivity and ion diffusion path are improved, which promotes the rapid extraction of Zn 2+ ions in the cathode and improves the reaction kinetics. The protective layer strategy aims to form a coating layer on the surface of the manganese-based cathode, such as carbon, conductive polymers and a series of metal oxides, to prevent direct contact with the electrolyte and thus reduce the dissolution of Mn 2+ . Cathode defect engineering aims to improve conductivity by adjusting the local electronic structure, while improving the diffusion capacity of zinc ions by introducing unsaturated sites as active chemisorption sites. Through the introduction of ions and molecules, ion / molecular pre-insertion can increase the interlayer spacing, thereby reducing the strong electrostatic interaction between highly polarized zinc ions and Mn-O layers. This method reduces the migration barrier of zinc ions and is considered a viable solution to improve reaction kinetics.

[0004] However, these strategies inevitably bring some negative effects. The morphology / structure design of cathode and the construction of protective layer inevitably lead to the reduction of active material. Defect engineering usually induces the instability of crystal structure, while ion / molecule pre-intercalation often leads to the blockage of ion channels. Although many studies have reported strategies to improve the electrochemical performance of manganese dioxide anodes, the theoretical capacity of manganese dioxide is still relatively low (250-308 mAh g -1 ). In recent years, low-valence manganese oxides, such as Mn3O4, Mn2O3 and MnO, have attracted widespread attention. Among them, due to its unique +2 and +3 mixed valence, the theoretical capacity of Mn3O4 is higher than that of Mn 4+ / Mn 3+ -based AZIBs (~308 mAh g -1 ) by 468.56 mAh g -1 , and is considered a promising anode material. However, the inherent shortcomings of manganese oxides, such as volume expansion, poor electronic / ionic conductivity, slow zinc ion reaction kinetics and dissolution problems, still need to be overcome in Mn3O4. These shortcomings often lead to rapid capacity decay and limited rate performance, hindering the practical application of Mn3O4 in AZIBs. In this work, we adopt a synthesis strategy to combine morphology / structure design, ion doping and protective layer encapsulation to address these challenges. SUMMARY

[0005] Technical problems solved:

[0006] The present application solves the technical problems of poor conductivity of manganese-based metal oxides, dissolution and volume expansion of Mn during the reaction, slow Zn 2+ reaction kinetics and other technical problems, and provides a potassium-doped chain-like trimanganese tetroxide positive electrode material, a preparation method and application thereof, so that the prepared zinc ion battery material can improve the conductivity of manganese-based materials, inhibit the inherent dissolution problem of manganese-based materials, and improve the electrochemical performance of zinc ion batteries.

[0007] Technical solutions:

[0008] To achieve the above-mentioned purpose, the technical solutions are as follows:

[0009] A potassium-doped chain-like trimanganese tetroxide positive electrode material, the positive electrode material is a K-Mn3O4-NCs@PANI composite material, the positive electrode material is composed of K-doped trimanganese tetroxide nanochains and a polyaniline protective layer tightly wrapped outside the trimanganese tetroxide nanochains, the diameter of the K-doped trimanganese tetroxide nanochains is 10-30 nm, and the thickness of the polyaniline coating is 5-10 nm.

[0010] A preparation method of a potassium-doped chain-like trimanganese tetroxide positive electrode material, specifically comprising the following steps:

[0011] Step 1: A mixed solution A of isopropyl alcohol and deionized water is configured, and under magnetic stirring, manganese acetate tetrahydrate, potassium chloride and nitrilotriacetic acid are dissolved into the mixed solution in a mass ratio of 8-9:1-2:1.5-3 to obtain a mixed solution B; then the mixed solution B is transferred to a reaction kettle and heated at 180 DEG C for 12 h; after the temperature of the reaction kettle drops to room temperature, the pink precipitate is washed with deionized water and anhydrous ethanol for three times, and then transferred to a vacuum drying box for drying to obtain K-Mn-NTA, a white powder K-Mn-NCs precursor;

[0012] Step 2: The white powder is ground and placed on a quartz boat, and the quartz boat is placed in a tube furnace, then calcined in an air environment for 4 hours, and K-Mn3O4-NCs powder is obtained after cooling;

[0013] Step 3: A mixed solution C of concentrated hydrochloric acid and deionized water is configured in a volume ratio of 1:40, and the mixed solution C is evenly placed in two beakers, which are respectively marked as A and B; aniline is added dropwise into beaker A and ultrasonically treated at a power of 180 W, and K-Mn3O4-NCs powder is dispersed into the ultrasonically treated solution; ammonium persulfate is added into beaker B and dissolved by stirring at a speed of 800 rpm, and then the solution is added dropwise into beaker A, and stirred at 800 rpm for 4 hours; finally, K-Mn3O4-NCs@PANI is obtained after centrifugation, ultrasonic washing and drying.

[0014] Further, in the first step, the volume ratio of isopropyl alcohol to deionized water is 1:4, the magnetic stirring speed is 800 rpm, and the amount of isopropyl alcohol and deionized water is 10 mL and 40 mL.

[0015] Further, in the first step, the amount of manganese acetate tetrahydrate, potassium chloride and nitrilotriacetic acid is 8 g, 1 g and 1.5 g respectively.

[0016] Further, in the first step, the temperature of vacuum drying is 60 DEG C, and the vacuum time is 8 h.

[0017] Further, in the second step, the calcination temperature is 400 DEG C.

[0018] Further, in the third step, the amount is 1 ml and 40 ml respectively.

[0019] Further, in the third step, the mass volume ratio of K-Mn3O4-NCs: aniline: ammonium persulfate is 0.4 g:200 μL:0.5 g.

[0020] Further, the third step is centrifugation at 6000 rpm for 15 min; ultrasonic cleaning at 180 W for 10 min, drying at 60℃ for 8h.

[0021] The application also discloses application of the potassium-doped chain-like trimanganese tetroxide positive electrode material in a water-based zinc ion battery.

[0022] Advantages:

[0023] The application provides a potassium-doped chain-like trimanganese tetroxide positive electrode material and a preparation method and application thereof.

[0024] 1. The application coats a PANI conductive protective layer on the K-Mn3O4-NCs to obtain a zinc ion battery positive electrode material with a network structure, and the positive electrode material has a high aspect ratio, high conductivity and good stability.

[0025] 2. The K + Doping can adjust the local electronic structure of the Mn3O4 cathode, induce oxygen vacancies, improve the conductivity, and provide more active sites for Zn 2+ Diffusion;

[0026] 3. The 1D K-Mn3O4-NCs in the application are composed of K-Mn3O4 nanoparticles and conductive carbon, thereby effectively reducing the contact resistance between particles and promoting the rapid transfer of electrons.

[0027] 4. The high aspect ratio of the K-Mn3O4-NCs significantly increases the electrochemical reaction area and shortens the diffusion length of Zn 2+ ;

[0028] 5. The polyaniline layer in the application is in-situ polymerized on the K-Mn3O4-NCs, which not only shields corrosion, but also connects the 1D K-Mn3O4-NCs into a continuous conductive network, inhibits volume expansion, and improves stability.

[0029] 6. The specific capacity of the positive electrode material for the positive electrode of the zinc ion battery is as high as 510 mAh g -1 Under a current density of 0.1 Ag -1 , and reaches 203 mAh g -1 Under a current density of 5 Ag -1 .

[0030] 7. The zinc ion battery of the present application has good cycle performance, and after 20000 cycles at 5 Ag -1 , the specific capacity is maintained at 90.3 mAh g -1 , and the average capacity per cycle decreases by 0.026 ‰. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a scanning electron microscope (SEM) image of K-Mn3O4-NCs@PANI obtained in Example 1 of the present application;

[0032] Figure 2 is a high-resolution transmission electron microscope (HRTEM) image of K-Mn3O4-NCs@PANI obtained in Example 1 of the present application;

[0033] Figure 3 is a structural schematic diagram of K-Mn3O4-NCs@PANI obtained in Example 1 of the present application;

[0034] Figure 4 is a transmission electron microscope (TEM) image of K-Mn3O4-NCs@PANI obtained in Example 1 of the present application;

[0035] Figure 5 is a rate performance diagram of zinc ion batteries of Example 1 and Comparative Examples 1, 2, 3, and 4 provided by the present application;

[0036] Figure 6 is a specific capacity and cycle performance diagram of zinc ion batteries of Example 1 and Comparative Examples 1, 2, 3, and 4 provided by the present application at 5 Ag -1 current density within 20000 cycles. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present application, the principles and features of the present application are described in detail below in combination with the drawings and preferred embodiments, and the embodiments are only used to explain the present application and do not limit the scope of the present application.

[0038] All raw materials of the present application are not particularly limited in source, and can be purchased on the market or prepared according to conventional methods well known to those skilled in the art.

[0039] In order to further illustrate the present application, the preparation method and application of the polyaniline-coated potassium-doped chain-like trimanganese tetraoxide zinc ion battery positive electrode material provided by the present application are described in detail below in combination with the embodiments.

[0040] Example 1:

[0041] A method for preparing a potassium-doped chain-like manganese tetroxide cathode material specifically includes the following steps:

[0042] Step 1: Prepare a mixed solution A of 10 mL isopropanol and 40 mL deionized water. Under magnetic stirring at 800 rpm, dissolve 8 g manganese acetate tetrahydrate, 1 g potassium chloride, and 1.5 g nitric acid in the mixed solution to obtain mixed solution B. Then transfer mixed solution B to a reaction vessel and heat at 180 °C for 12 h. After the reaction vessel temperature drops to room temperature, wash the pink precipitate three times with deionized water and anhydrous ethanol. After washing, transfer the precipitate to a vacuum drying oven and dry at 60 °C for 12 h to obtain K-Mn-NTA, i.e., a white powder.

[0043] K-Mn-NCs precursors;

[0044] Step 2: Grind the white powder and place it on a quartz boat. Then, place the quartz boat in a tube furnace and heat it in air.

[0045] K-Mn3O4-NCs powder can be obtained by calcining at 400℃ for 4 hours and then cooling.

[0046] Step 3: Prepare a mixed solution C by mixing 1 mL of concentrated hydrochloric acid with 40 mL of deionized water. Distribute the mixed solution C evenly into two beakers, labeled A and B respectively. Add 200 μL of aniline dropwise to beaker A and sonicate it at a power of 180 W. Disperse K-Mn3O4-NCs powder into the sonicated solution. Add 0.5 g of ammonium persulfate to beaker B and stir at 800 rpm to dissolve it. Then add this solution dropwise to beaker A and stir at 800 rpm for 4 hours. Finally, after centrifugation, ultrasonic washing, and drying at 60–75 °C for 12 hours, centrifuge at 6000 rpm for 15 min. Ultrasonic cleaning is performed at a power of 180 W for 10 min to obtain K-Mn3O4-NCs@PANI.

[0047] Figure 1 This is a scanning electron microscope (SEM) image of K-Mn3O4-NCs@PANI obtained in Example 1. Figure 1 Due to the encapsulation with polyaniline, the surface of K-Mn3O4-NCs@PANI becomes smoother, and the diameter of these chain-like structures is approximately 30 nm. Figure 2 High-resolution transmission electron microscopy (HRTEM) image of K-Mn3O4-NCs@PANI. (Source: [Original Text]) Figure 2 It can be seen that the lattice spacing of the composite material is approximately 0.31 nm. Figure 3The diagram shows the K-Mn3O4-NCs@PANI structure obtained in Example 1 of this invention. It can be seen that the above materials eventually form a conductive network. The 1D K-Mn3O4-NCs are protected inside the PANI layer, and the K-Mn3O4k particles are interconnected to form a stable one-dimensional chain structure. Figure 4 The image shown is a transmission electron microscope (TEM) image of K-Mn3O4-NCs@PANI obtained in Example 1 of this invention. It can be seen that the PANI protective layer is very comprehensively wrapped on the surface of the K-Mn3O4-NCs nanochains.

[0048] Application of potassium-doped chain-like manganese tetroxide cathode material in aqueous zinc-ion batteries:

[0049] Step 1, preparation of slurry: K-Mn3O4-NCs@PANI is thoroughly ground and stirred with conductive carbon black and binder (PVDF) in a ratio of 8:1:1, and the mixture is then uniformly mixed to form a slurry;

[0050] Step 2: Use a mold to evenly coat the slurry onto the titanium foil, and then transfer the titanium foil to a vacuum drying oven to dry at 50°C for 10 hours;

[0051] Step 3, Electrode sheet fabrication: Cut the dried titanium foil into small circular pieces with a diameter of 16mm. These circular pieces are the positive electrode sheets.

[0052] Step 4: Use the prepared circular electrode as the positive electrode and the glass fiber filter membrane as the diaphragm, 2 mol L -1 Using ZnSO4 solution as the electrolyte and zinc sheet as the negative electrode, a coin-type CR2032 symmetrical battery was assembled in the following order: negative electrode shell, spring, gasket, negative electrode sheet, separator, positive electrode sheet, and positive electrode shell. Electrochemical performance was tested after standing for 12 hours.

[0053] Example 2:

[0054] A method for preparing a potassium-doped chain-like manganese tetroxide cathode material specifically includes the following steps:

[0055] Step 1: Prepare a mixed solution A of 10 mL isopropanol and 40 mL deionized water. Under magnetic stirring at 800 rpm, dissolve 6 g manganese acetate tetrahydrate, 0.8 g potassium chloride, and 1 g nitric acid triacetic acid into the mixed solution to obtain mixed solution B. Then, transfer mixed solution B to a reaction vessel and heat at 180 °C for 12 h. After the reaction vessel temperature drops to room temperature, wash the pink precipitate three times with deionized water and anhydrous ethanol. After washing, transfer it to a vacuum drying oven and dry at 60 °C for 12 h to obtain K-Mn-NTA, i.e., the white powder K-Mn-NCs precursor.

[0056] Second step: After grinding the white powder, place it on a quartz boat and put the quartz boat in a tube furnace, then calcine it at 350°C for 4 hours in an air environment. After cooling, K-Mn3O4-NCs powder is obtained;

[0057] Third step: Prepare mixed solution C by mixing 1 ml of concentrated hydrochloric acid and 40 ml of deionized water. Take an equal amount of mixed solution C and place it in two beakers, labeled A and B respectively. Add 150 μL of aniline dropwise to beaker A and ultrasonicate it at a power of 180 W. Disperse K-Mn3O4-NCs powder into the ultrasonicated solution. Add 0.4 g of ammonium persulfate to beaker B and stir to dissolve at a stirring speed of 800 rpm. Then, add the solution dropwise to beaker A. Finally, stir at 800 rpm for 4 hours. After centrifugation, ultrasonic washing, and drying at 60-75°C for 12 hours, centrifuge at 6000 rpm for 15 minutes and ultrasonic clean at 180 W for 10 minutes to obtain K-Mn3O4-NCs@PANI.

[0058] Comparative Example 1

[0059] A method for preparing a positive electrode material, specifically comprising the following steps:

[0060] First step: Prepare mixed solution A by mixing 10 mL of isopropyl alcohol and 40 mL of deionized water. Dissolve 8 g of manganese acetate tetrahydrate, 1 g of potassium chloride, and 1.5 g of nitrilotriacetic acid into the mixed solution under magnetic stirring at 800 rpm to obtain mixed solution B. Then, transfer mixed solution B to a reaction kettle and heat it at 180°C for 12 h. When the temperature of the reaction kettle drops to room temperature, wash the pink precipitate with deionized water and anhydrous ethanol three times, and then transfer it to a vacuum drying oven for drying at 60°C for 12 h to obtain K-Mn-NTA, which is a white powder K-Mn-NCs precursor.

[0061] Second step: After grinding the white powder, place it on a quartz boat and put the quartz boat in a tube furnace, then calcine it at 400°C for 4 hours in an air environment. After cooling, K-Mn3O4-NCs powder is obtained;

[0062] Third step, preparation of slurry: Grind, stir, and mix K-Mn3O4-NCs, conductive carbon black, and binder (PVDF) in a ratio of 8:1:1 to prepare a slurry.

[0063] Step 2: Use a mold to evenly coat the slurry on a titanium foil, then transfer the titanium foil to a vacuum drying oven for drying at 50°C for 10 hours.

[0064] Step 3, preparation of electrode sheet: Cut the dried titanium foil into small round pieces with a diameter of 16 mm. These round pieces are the positive electrode sheets.

[0065] Step 4: The prepared circular electrode was used as the positive electrode, the glass fiber filter membrane was used as the separator, and 2 mol L -1 ZnSO4 solution was used as the electrolyte, and zinc sheet was used as the negative electrode. The negative electrode shell, spring, gasket, negative electrode sheet, separator, positive electrode sheet, and positive electrode shell were assembled in order to form a button CR2032 symmetric battery. After standing for 12 h, the electrochemical performance was tested.

[0066] Comparative Example 2:

[0067] A preparation method of a positive electrode material, specifically comprising the following steps:

[0068] First step: A mixed solution A of isopropyl alcohol 10 mL and deionized water 40 mL was prepared, and 8 g of manganese acetate tetrahydrate and 1.5 g of nitrilotriacetic acid were dissolved in the mixed solution to obtain a mixed solution B under magnetic stirring at 800 rpm; then the mixed solution B was transferred to a reaction kettle and heated at 180°C for 12 h; after the temperature of the reaction kettle dropped to room temperature, the pink precipitate was washed with deionized water and anhydrous ethanol for three times and transferred to a vacuum drying oven for drying at 60°C for 12 h to obtain Mn-NTA, i.e., white powder Mn-NCs precursor;

[0069] Second step: The white powder was ground and placed on a quartz boat, and the quartz boat was placed in a tube furnace, then calcined at 400°C for 4 hours in an air environment, and after cooling, Mn3O4-NCs powder was obtained;

[0070] Third step, preparation of slurry: Mn3O4-NCs, conductive carbon black, and binder (PVDF) were fully ground, stirred, and mixed in a ratio of 8:1:1 to prepare the slurry;

[0071] Step 2: The slurry was uniformly coated on the titanium foil using a mold, and then the titanium foil was transferred to a vacuum drying oven for drying at 50°C for 10 hours;

[0072] Step 3, preparation of electrode sheet: The dried titanium foil was cut into small circular pieces with a diameter of 16 mm, which were the positive electrode sheets;

[0073] Step 4: The prepared circular electrode was used as the positive electrode, the glass fiber filter membrane was used as the separator, and 2 mol L -1 ZnSO4 solution was used as the electrolyte, and zinc sheet was used as the negative electrode. The negative electrode shell, spring, gasket, negative electrode sheet, separator, positive electrode sheet, and positive electrode shell were assembled in order to form a button CR2032 symmetric battery. After standing for 12 h, the electrochemical performance was tested.

[0074] Comparative Example 3:

[0075] A preparation method of a positive electrode material, specifically comprising the following steps:

[0076] First step: configure a mixed solution A of isopropyl alcohol 10 mL and deionized water 40 mL, dissolve 8 g of manganese acetate tetrahydrate into the mixed solution under magnetic stirring at 800 rpm to obtain a mixed solution B; then transfer the mixed solution B into a reaction kettle and heat at 180℃

[0077] for 12 h; when the temperature of the reaction kettle drops to room temperature, wash the pink precipitate with deionized water and anhydrous ethanol for three times, and transfer to a vacuum drying oven for drying at 60℃ for 12 h to obtain a Mn salt, i.e., a Mn precursor;

[0078] Second step: grind the Mn precursor powder, place it on a quartz boat and put the quartz boat into a tube furnace, and then calcine at 400℃ for 4 h in an air environment; after cooling, Mn3O4 is obtained;

[0079] Third step, preparation of slurry: Mn3O4, conductive carbon black and binder (PVDF) are fully ground, stirred and mixed in a ratio of 8:1:1 to prepare a slurry;

[0080] Step 2: use a mold to evenly coat the slurry on a titanium foil, and then transfer the titanium foil to a vacuum drying oven for drying at 50℃ for 10 h;

[0081] Step 3: preparation of electrode sheet: cut the dried titanium foil into small round sheets with a diameter of 16 mm, which are positive electrode sheets;

[0082] Step 4: use the prepared round electrode sheet as a positive electrode, a glass fiber filter membrane as a separator, 2 mol L -1 of ZnSO4 solution as an electrolyte, and a zinc sheet as a negative electrode, to assemble a button CR2032 symmetrical battery in the order of negative electrode shell, spring, gasket, negative electrode sheet, separator, positive electrode sheet and positive electrode shell. After standing for 12 h, test the electrochemical performance.

[0083] Test example

[0084] The zinc ion batteries obtained in Example 1 and Comparative Examples 1, 2 and 3 were subjected to constant current charge-discharge, cycle performance test and rate performance test by using a charge-discharge instrument of Shenzhen Xinwei Co., Ltd. The test temperature in this paper was ambient temperature 26℃, and the charge-discharge voltage cutoff range was 0.8-1.8 V. The test results are shown in Figure 5 and Figure 6 .

[0085] Figure 5 The rate performance graph of the zinc ion batteries obtained in Example 1 and Comparative Examples 1, 2 and 3 provided by the present application is provided. The discharge specific capacity of the zinc ion battery assembled by using K-Mn3O4-NCs@PANI provided in this Example 1 as a positive electrode material is 501.5 mAh g -1 at 0.1 Ag -1to 5 Ag -1 203.2 mAh g -1 , the capacity retention rate was 40.5%, and when the current density returned to 5 Ag -1 , the corresponding capacity was restored to 491.5 mAh g -1 , with strong reversibility. The specific capacity of Comparative Examples 1, 2 and 3 at each current density was significantly lower than that of the zinc ion battery with K-Mn3O4-NCs@PANI as the positive electrode. Figure 6 The long cycle performance of the zinc ion battery obtained by Example 1 and Comparative Examples 1, 2 and 3 of the present application is shown in the graph. Figure 6 As can be seen from the graph, the zinc ion battery assembled with K-Mn3O4-NCs@PANI as the positive electrode material provided by Example 1 had excellent long cycle performance at a current density of 5 Ag -1 , with an initial capacity of 190.0 mAh g -1 , and still maintaining a specific capacity of 90.3 mAh g -1 after 20,000 cycles, with an average capacity decrease of 0.026‰ per cycle. The capacity of the zinc ion battery with the electrode material of Comparative Examples 1, 2 and 3 decayed rapidly, and the stability of the discharge specific capacity was poor, and the manganese dissolved severely. The zinc ion battery with the K-Mn3O4-NCs@PANI material as the electrode had excellent rate performance and high stability, and exhibited excellent electrochemical performance, with good initial specific capacity, cycle performance and rate performance.

[0086] The above has exemplarily described the present application, and it should be noted that any simple modification, change or equivalent replacement without creative labor by those skilled in the art without departing from the core of the present application falls within the protection scope of the present application.

Claims

1. A potassium-doped chain-like trimanganese tetroxide anode material, the anode material is a K-Mn3O4-NCs@PANI composite material, the anode material is composed of K-doped trimanganese tetroxide nanochains and a polyaniline protective layer tightly wrapped outside the trimanganese tetroxide nanochains, the K-doped trimanganese tetroxide nanochains have a diameter of 10-30 nm, and the polyaniline coating has a thickness of 5-10 nm.

2. The method for preparing the potassium-doped chain-type trimanganese tetraoxide cathode material of claim 1, characterized in that, Specifically comprising the following steps: In the first step, a mixed solution A of isopropyl alcohol and deionized water is prepared, under magnetic stirring, manganese acetate tetrahydrate, potassium chloride and nitrilotriacetic acid are dissolved into the mixed solution in a mass ratio of 8-9:1-2:1.5-3 to obtain a mixed solution B; then the mixed solution B is transferred into a reaction kettle and heated at 180℃ for 12 h; after the temperature of the reaction kettle decreases to room temperature, the pink precipitate is washed with deionized water and anhydrous ethanol for three times, and then transferred into a vacuum drying box to obtain K-Mn-NTA, i.e., a white powder K-Mn-NCs precursor, after drying; In the second step, the white powder is ground and placed on a quartz boat which is placed in a tube furnace, and then calcined in an air environment for 4 hours, and the K-Mn3O4-NCs powder is obtained after cooling; In the third step, a mixed solution C of concentrated hydrochloric acid and deionized water is prepared in a volume ratio of 1:40, the mixed solution C is evenly placed in two beakers, which are respectively marked as A and B; aniline is added dropwise into beaker A and ultrasonically treated at a power of 180 W, and K-Mn3O4-NCs powder is dispersed into the solution after ultrasonic treatment; ammonium persulfate is added into beaker B and dissolved by stirring at a speed of 800 rpm, and then the solution is added dropwise into beaker A, and stirred at 800 rpm for 4 hours; finally, K-Mn3O4-NCs@PANI is obtained after centrifugation, ultrasonic washing and drying.

3. The method of claim 2, wherein the method further comprises: In the first step, the volume ratio of isopropyl alcohol to deionized water is 1:4, the magnetic stirring speed is 800 rpm, and the amount of isopropyl alcohol and deionized water is 10 mL and 40 mL. ​ 4. The method of claim 2, wherein the potassium-doped chain-type trimanganese tetraoxide cathode material is prepared by the following steps of: In the first step, the amount of manganese acetate tetrahydrate, potassium chloride and nitrilotriacetic acid is 8 g, 1 g and 1.5 g, respectively. ​ 5. The method of claim 2, wherein the potassium-doped chain-type trimanganese tetraoxide cathode material is prepared by the following steps of: In the first step, the temperature of vacuum drying is 60℃, and the vacuum time is 8 h. ​ 6. The method for preparing the potassium-doped chain-like manganese tetroxide cathode material according to claim 2, characterized in that, In the second step, the calcination temperature is 400℃.

7. The method for preparing the potassium-doped chain-like manganese tetroxide cathode material according to claim 2, characterized in that, In the third step, the amount of concentrated hydrochloric acid and deionized water is 1 ml and 40 ml, respectively.

8. The method for preparing the potassium-doped chain-like manganese tetroxide cathode material according to claim 2, characterized in that, In the third step, the mass volume ratio of K-Mn3O4-NCs, aniline and ammonium persulfate is 0.4 g:200 μL:0.5 g.

9. The method for preparing the potassium-doped chain-like manganese tetroxide cathode material according to claim 2, characterized in that, In the third step, the centrifuge speed is 6000 rpm, the centrifugation time is 15 min, the ultrasonic cleaning machine power is 180 W, the ultrasonic time is 10 min, the drying temperature is 60℃, and the drying time is 8 h.

10. The use of the potassium-doped chain-type trimanganese tetraoxide cathode material of claim 1 in a water-based zinc ion battery, characterized in that: The potassium-doped chain-type trimanganese tetraoxide positive electrode material is used as a positive electrode of a water-based zinc ion battery, 2M zinc sulfate aqueous solution is used as an electrolyte, glass fiber GF-D is used as a diaphragm, a zinc sheet is used as a negative electrode, and a CR2032 battery shell is used to assemble a zinc ion battery at room temperature; and the assembled battery is subjected to long cycle test on a battery test cabinet Neware BTS 7.6.0.

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