Aqueous zinc ion battery negative electrode material with polymer modification layer and preparation method of aqueous zinc ion battery negative electrode material

Abstract

The invention discloses an aqueous zinc ion battery negative electrode material with a polymer modification layer and a preparation method of the aqueous zinc ion battery negative electrode material, valine-doped polyaniline is prepared by a chemical oxidation method, the required aqueous zinc ion battery negative electrode material is prepared by a dispensing method, and the aqueous zinc ion battery negative electrode material is simple to prepare and easy to operate. When the water-based zinc ion battery electrolyte is applied to a water-based zinc ion battery, the cycle performance of the water-based zinc ion battery can be effectively improved, the water-based zinc ion battery has a good and stable deposition / stripping process, the performance is excellent under different current densities, an obvious effect of inhibiting zinc dendrites is achieved, and commercialization of the water-based zinc ion battery is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode materials for batteries, and particularly relates to a negative electrode material for an aqueous zinc-ion battery with a polymer modification layer and a preparation method thereof. Background Art

[0002] The depletion of fossil energy and environmental deterioration are two major severe challenges faced by humanity currently. Developing advanced electrochemical energy storage devices to safely collect and store renewable clean energy is considered the key to solving the above problems. Aqueous zinc-ion batteries (AZIBs) stand out among energy storage devices due to their high theoretical capacity (820 mAh g -1 ), low reduction potential (-0.762 V vs. SHE), low cost, high safety, etc. Therefore, aqueous zinc-ion batteries have great potential in addressing the challenges of power conversion and storage technologies and are expected to become candidates for the next-generation large-scale energy storage devices.

[0003] However, the large-scale application of aqueous zinc-ion batteries still faces some problems. Since zinc ions are prone to uneven deposition during the deposition / stripping process and tend to accumulate in areas with high current density, forming zinc dendrites, these dendrites can penetrate the separator, resulting in short circuits and greatly reducing the service life of the battery. In addition, the grown zinc dendrites may fall off, forming "dead zinc", leading to the loss of anode material and a decrease in Coulombic efficiency; more importantly, in a weakly acidic electrolyte, hydrogen evolution (HER) and corrosion of the zinc negative electrode destroy the reversibility of the cycle, inevitably reducing the battery life and Coulombic efficiency.

[0004] Currently, the key research issues of aqueous zinc-ion batteries mainly focus on the zinc negative electrode, and the solution strategies can be roughly divided into three categories: interface protection layer strategy, electrolyte modification strategy, and zinc negative electrode structure optimization. Constructing an inorganic or organic protection layer on the zinc metal surface can provide an isolation barrier between the electrode and the electrolyte, isolate the direct contact between metallic zinc and the electrolyte, and prevent side reactions from occurring. In addition, an inert physical protection layer with a high Young's modulus can significantly prevent the generation of zinc dendrites; the electrolyte modification strategy can adjust the solvation structure of zinc ions, thereby preventing side reactions from occurring.

[0005] Chinese Patent Application CN114824195A discloses a composite negative electrode material for a zinc battery, a preparation method thereof, and an application. The composite negative electrode material includes metallic zinc Zn and copper telluride Cu xA mixture of Te; the preparation method includes: mixing copper telluride powder and zinc powder, and ball-milling under a protective atmosphere of inert gas to obtain zinc powder coated with copper telluride; or grinding and mixing copper telluride powder, organic solvent and binder evenly, then coating on a zinc sheet and drying in vacuum to obtain a zinc sheet coated with copper telluride. The composite anode material is used in aqueous zinc-ion batteries or non-aqueous zinc-ion batteries. The invention can solve the problems of zinc dendrites and low capacity and high potential of the embedded anode material, and has outstanding electrochemical performance. Chinese Patent Application CN115810708A discloses a nitrogen-doped carbon-coated zinc powder anode for zinc-ion batteries, its preparation method and application, including the steps: 1. ultrasonically cleaning zinc powder; 2. preparing a PVP solution; 3. ultrasonically oscillating zinc powder and PVP solution; 4. drying and volatilizing ethanol to obtain PVP-coated zinc powder; 5. calcining the sample and cooling it; 6. making an anode; 7. assembling a symmetric electrolyte to test the cycling performance of the anode, assembling an aqueous zinc-ion battery, and assembling a quasi-solid-state battery. The invention performs nitrogen-doped carbon coating treatment on commercial zinc powder, with simple process, convenient operation, strong controllability and repeatability, and can be prepared on a large scale. Compared with traditional commercial zinc powder and zinc foil, the nitrogen-doped carbon-coated zinc powder is more uniformly and densely deposited during continuous cycling. Therefore, whether as the anode of a zinc-ion battery in a symmetric battery or a full battery, the cycling stability of the nitrogen-doped carbon-coated zinc powder has been significantly improved. However, these methods have cumbersome processing procedures, large interfacial impedance, and the loadable cycling current density of the prepared anode material is small, which to a certain extent affects the overall stability of the battery and needs to be further improved. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a cathode material for aqueous zinc-ion batteries with a polymer modification layer and its preparation method. Valine-doped polyaniline is prepared by a chemical oxidation method, and the required cathode material for aqueous zinc-ion batteries is prepared by a drop-coating method. The preparation of this cathode material for aqueous zinc-ion batteries is simple and easy to operate.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A cathode material for aqueous zinc-ion batteries with a polymer modification layer, the cathode material for aqueous zinc-ion batteries is obtained by drop-coating a polymer modification layer slurry on a zinc cathode and drying; the polymer modification layer slurry includes valine-doped polyaniline, a binder and an organic solvent.

[0009] Preferably, the zinc cathode is a zinc foil with a thickness of 80 - 100 μm, and the structural formula of the valine-doped polyaniline is as follows:

[0010]

[0011] Preferably, the thickness of the polymer modification layer is 10 - 20 μm.

[0012] More preferably, the thickness of the polymer modification layer can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm; however, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0013] The present invention also protects a preparation method of a negative electrode material for an aqueous zinc - ion battery with the polymer modification layer as described above, comprising the following steps:

[0014] S1. Add aniline and valine into deionized water, mix evenly, then dropwise add ammonium persulfate solution, carry out stirring reaction, after the reaction is completed, filter by suction and dry to obtain valine - doped polyaniline;

[0015] S2. Add the valine - doped polyaniline in step S1 into an organic solvent, then add a binder, mix evenly to obtain a polymer modification layer slurry, and then drop - coat it on the zinc negative electrode and dry to obtain the negative electrode material for the aqueous zinc - ion battery with the polymer modification layer.

[0016] Preferably, in step S1, the concentration of the ammonium persulfate solution is 200 - 250 g / L, and the mass ratio of aniline, valine, deionized water, and ammonium persulfate solution is 1.5 - 2.5:0.5 - 0.7:70 - 100:24 - 26.

[0017] Preferably, the dropping rate in step S1 is 1 - 1.5 mL / min.

[0018] Preferably, the temperature of the stirring reaction in step S1 is 20 - 30 °C, and the time is 12 - 24 h.

[0019] More preferably, the temperature of the stirring reaction in step S1 can be 20 °C, 21 °C, 22 °C, 23 °C, 24 °C, 25 °C, 26 °C, 27 °C, 28 °C, 29 °C, 30 °C, and the time can be 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h; however, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0020] Preferably, in step S2, the organic solvent is N - methylpyrrolidone or water, and the binder is polyvinylidene fluoride or carboxymethyl cellulose.

[0021] Preferably, the mass ratio of the binder to the valine - doped polyaniline in step S2 is 1:2 - 9; the drying temperature is 60 - 80 °C, and the time is 4 - 10 h.

[0022] More preferably, the mass ratio of the binder and valine-doped polyaniline described in step S2 can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9; the drying temperature can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, and the time can be 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h; however, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] The present invention also protects the application of the negative electrode material of the aqueous zinc ion battery with the polymer modification layer as described above in the aqueous zinc ion battery.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The negative electrode material of the aqueous zinc ion battery with the polymer modification layer provided by the present invention effectively improves the comprehensive electrochemical performance of the aqueous zinc ion battery by constructing a valine-doped polyaniline (VPANI) interfacial protection layer; the -NH-, =N-, -NH 2 active functional groups in the polymer modification layer can form hydrogen bonds with the water sheath layer in the hydrated zinc ions, thereby improving the desolvation ability, reducing the hydrogen evolution reaction caused by the contact of water molecules with metallic zinc, inhibiting the hydrogen evolution corrosion of the zinc negative electrode, maintaining the coulombic efficiency at a high level, and significantly prolonging the battery cycle life; at the same time, the functional groups in the modification layer have lone pair electrons, which can induce the rapid removal of zinc ions in the hydrated zinc ions, improve the transport efficiency of zinc ions in the electrolyte, promote the uniform deposition of zinc ions, and show excellent deposition / stripping reversibility at different current densities, and the cycle stability is significantly improved compared with the unmodified system; the amount of by-products generated at the modified electrode / electrolyte interface is reduced, and the charge transfer resistance is decreased, effectively improving the electrochemical stability of the zinc negative electrode.

[0026] (2) The negative electrode material of the aqueous zinc ion battery with the polymer modification layer provided by the present invention has the polymer modification layer doped with valine in polyaniline. The introduction of valine molecules can not only increase the richness of active functional groups but also help to regulate the hydrophilicity and hydrophobicity of the polymer modification layer. The hydrophobic alkyl chain of valine reduces the water permeability of the interface layer, while its hydrophilic carboxylic acid group maintains an appropriate ionic conduction ability. This microenvironment regulation reduces the direct contact area of the electrolyte and at the same time ensures the necessary zinc ion migration channels, suppressing side reactions while maintaining the electrode reaction kinetics.

[0027] (3) The anode material for aqueous zinc-ion batteries with a polymer modification layer provided by the present invention helps to improve the dual coupling effect of desolvation and uniform electric field to regulate the zinc-ion deposition process. The polar functional groups in VPANI can partially strip the solvation sheath of Zn2+, reducing the deposition activation energy. At the same time, its high dielectric constant characteristic makes the interfacial electric field distribution more uniform, avoiding the concentration of local current density.

[0028] (4) The anode material for aqueous zinc-ion batteries with a polymer modification layer provided by the present invention can effectively improve the cycling performance of aqueous zinc-ion batteries, enabling the aqueous zinc-ion batteries to have a good and stable deposition / stripping process, excellent performance at different current densities, and an obvious effect on inhibiting zinc dendrites, which helps to realize the commercialization of aqueous zinc-ion batteries. Description of the Drawings

[0029] Figure 1 SEM image of valine-doped polyaniline (VPANI) prepared in Example 1 of the present invention;

[0030] Figure 2 Infrared spectra of valine-doped polyaniline (VPANI) prepared in Example 1 of the present invention, polyaniline (PANI) prepared in Comparative Example 1, and valine (Val);

[0031] Figure 3 Charge-discharge curves of symmetric cells of the anode material for aqueous zinc-ion batteries with a polymer modification layer (VPANI@Zn) prepared in Example 1 of the present invention, the anode material for aqueous zinc-ion batteries with a polymer modification layer (PANI@Zn) prepared in Comparative Example 1, and a pure zinc electrode at a current density of 1 mA·cm -2 and a areal capacity of 1 mAh·cm -2 ;

[0032] Figure 4 Charge-discharge curves of asymmetric cells of the anode material for aqueous zinc-ion batteries with a polymer modification layer (Cu / / VPANI@Zn) prepared in Example 1 of the present invention, the anode material for aqueous zinc-ion batteries with a polymer modification layer (Cu / / PANI@Zn) prepared in Comparative Example 1, and a pure zinc electrode at a current density of 2 mA·cm -2 and a areal capacity of 1 mAh·cm -2 ;

[0033] Figure 5 Anode material for aqueous zinc-ion batteries with a polymer modification layer (MnO 2 / / VPANI@Zn) prepared in Example 1 of the present invention, anode material for aqueous zinc-ion batteries with a polymer modification layer (MnO 2 / / Rate performance of the (PANI@Zn) and pure zinc electrodes in the full cell at different current densities;

[0034] Figure 6 The negative electrode material of the aqueous zinc-ion battery with a polymer modification layer prepared in Example 1 of the present invention (MnO 2 / / The negative electrode material of the aqueous zinc-ion battery with a polymer modification layer prepared in Comparative Example 1 (MnO 2 / / (PANI@Zn) and the pure zinc electrode in the full cell at 1Ag -1 The cycling performance below. Detailed implementation manners

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Example 1

[0037] A preparation method of a negative electrode material for an aqueous zinc-ion battery with a polymer modification layer includes the following steps:

[0038] S1. Add 1.86 g of aniline and 0.584 g of valine to 80 g of deionized water to obtain solution A. Subsequently, dissolve 4.56 g of ammonium persulfate in 20 mL of deionized water to obtain solution B. Use a peristaltic pump to drop solution B into solution A at a speed of 1 mL / min. After the dropping is completed, stir and react at 25 °C for 12 h. Then, perform suction filtration with absolute ethanol and pure water in sequence, and dry at 60 °C to obtain valine-doped polyaniline (VPANI);

[0039] S2. Add 45 mg of valine-doped polyaniline and 5 mg of polyvinylidene fluoride (PVDF) to 3 mL of N-methylpyrrolidone, and mix evenly to obtain a polymer modification layer slurry; Cut a zinc foil with a thickness of 90 μm into circular electrodes with a diameter of 14 mm, add ethanol for ultrasonic cleaning and air drying; Then, use a pipette to drop the polymer modification layer slurry onto the surface of the zinc foil, and dry at 70 °C for 8 h to obtain the negative electrode material of the aqueous zinc-ion battery with the polymer modification layer (with a thickness of 12 μm), denoted as VPANI@Zn.

[0040] Example 2

[0041] A preparation method of a negative electrode material for an aqueous zinc-ion battery with a polymer modification layer includes the following steps:

[0042] S1. Add 2.5 g of aniline and 0.7 g of valine to 100 g of deionized water to obtain solution A. Subsequently, dissolve 5 g of ammonium persulfate in 20 mL of deionized water to obtain solution B. Use a peristaltic pump to drip solution B into solution A at a rate of 1.3 mL / min. After the dripping is completed, stir and react at 20 °C for 24 h. Then, filter successively with absolute ethanol and pure water, and dry at 60 °C to obtain valine-doped polyaniline (VPANI);

[0043] S2. Add 45 mg of valine-doped polyaniline and 5 mg of polyvinylidene fluoride (PVDF) to 1 mL of N-methylpyrrolidone, and mix evenly to obtain the polymer-modified layer slurry; Cut a zinc foil with a thickness of 80 μm into circular electrodes with a diameter of 14 mm, add ethanol for ultrasonic cleaning and air drying; Then, use a pipette to drip the polymer-modified layer slurry onto the surface of the zinc foil, and dry at 80 °C for 4 h to obtain the negative electrode material of the aqueous zinc-ion battery with the polymer-modified layer (thickness: 10 μm).

[0044] Example 3

[0045] A preparation method of a negative electrode material for an aqueous zinc-ion battery with a polymer-modified layer, comprising the following steps:

[0046] S1. Add 1.5 g of aniline and 0.5 g of valine to 70 g of deionized water to obtain solution A. Subsequently, dissolve 4 g of ammonium persulfate in 20 mL of deionized water to obtain solution B. Use a peristaltic pump to drip solution B into solution A at a rate of 1.5 mL / min. After the dripping is completed, stir and react at 30 °C for 12 h. Then, filter successively with absolute ethanol and pure water, and dry at 60 °C to obtain valine-doped polyaniline (VPANI);

[0047] S2. Add 45 mg of valine-doped polyaniline and 5 mg of polyvinylidene fluoride (PVDF) to 5 mL of N-methylpyrrolidone, and mix evenly to obtain the polymer-modified layer slurry; Cut a zinc foil with a thickness of 100 μm into circular electrodes with a diameter of 14 mm, add ethanol for ultrasonic cleaning and air drying; Then, use a pipette to drip the polymer-modified layer slurry onto the surface of the zinc foil, and dry at 60 °C for 10 h to obtain the negative electrode material of the aqueous zinc-ion battery with the polymer-modified layer (thickness: 20 μm).

[0048] Comparative Example 1

[0049] A preparation method of a negative electrode material for an aqueous zinc-ion battery with a polymer-modified layer, comprising the following steps:

[0050] S1. Add 1.86 g of aniline to 80 g of deionized water to obtain solution A. Subsequently, dissolve 4.56 g of ammonium persulfate in 20 mL of deionized water to obtain solution B. Use a peristaltic pump to drip solution B into solution A at a rate of 1 mL / min. After the dripping is completed, stir and react at 25 °C for 12 h. Then, perform suction filtration successively with absolute ethanol and pure water, and dry at 60 °C to obtain polyaniline (PANI).

[0051] S2. Add 45 mg of polyaniline and 5 mg of polyvinylidene fluoride (PVDF) to 3 mL of N-methylpyrrolidone, and mix evenly to obtain the polymer-modified layer slurry. Cut a zinc foil with a thickness of 90 μm into circular electrodes with a diameter of 14 mm, add ethanol for ultrasonic cleaning, and air dry. Then, use a pipette to drop-cast the polymer-modified layer slurry on the surface of the zinc foil and dry at 70 °C for 8 h to obtain the negative electrode material (with a thickness of 12 μm) of the aqueous zinc-ion battery with the polymer-modified layer, denoted as PANI@Zn.

[0052] As Figure 2 shown, by comparing the infrared spectra of VPANI, PANI, and valine, it is proved that valine is doped into polyaniline.

[0053] Application Example 1: Assembly of Symmetric Battery

[0054] Use the negative electrode material of the aqueous zinc-ion battery with the polymer-modified layer prepared in Example 1 as the positive and negative electrodes of the symmetric battery. The electrolyte used is 2 M Zn(SO4) 2 , and the dosage is 130 μL. Under normal temperature and atmospheric conditions, assemble the VPANI@Zn / / VPANI@Zn symmetric battery. The battery case model used is CR2032. The assembly sequence of the aqueous zinc-ion battery is successively the positive electrode case, the negative electrode material of the aqueous zinc-ion battery coated with the polymer-modified layer, the glass fiber separator (GF / D), the negative electrode material of the aqueous zinc-ion battery coated with the polymer-modified layer, the gasket, the spring piece, and the positive electrode case.

[0055] Use the negative electrode material of the aqueous zinc-ion battery with the polymer-modified layer prepared in Comparative Example 1 as the positive and negative electrodes of the symmetric battery. The electrolyte used is 2 M Zn(SO4) 2 , and the dosage is 130 μL. Under normal temperature and atmospheric conditions, assemble the PANI@Zn / / PANI@Zn symmetric battery. The battery case model used is CR2032. The assembly sequence of the aqueous zinc-ion battery is successively the positive electrode case, the negative electrode material of the aqueous zinc-ion battery coated with the polymer-modified layer, the glass fiber separator (GF / D), the negative electrode material of the aqueous zinc-ion battery coated with the polymer-modified layer, the gasket, the spring piece, and the positive electrode case.

[0056] Pure zinc electrode symmetric battery: The assembly method is the same as above, except that 99% pure zinc foils are used for both the positive and negative electrode plates, denoted as Zn / / Zn symmetric battery.

[0057] Test results: The voltage-time curve performance of the assembled VPANI@Zn / / VPANI@Zn, PANI@Zn / / PANI@Zn, and Zn / / Zn symmetric cells at a current of 1 mA cm -2 and an areal capacity of 1 mAh cm -2 is as follows Figure 3 shown. The experimental results prove that VPANI@Zn / / VPANI@Zn can withstand stable cycling for 1000 hours without short circuit, which is superior to that of Comparative Example 1 and pure zinc sheet in ZnSO 4 electrolyte in terms of electrochemical performance.

[0058] Application Example 2: Assembly of Asymmetric Cells

[0059] Using a pure copper (16 mm) electrode sheet as the positive electrode sheet of a button cell, placing a separator, dropping an electrolyte, and then placing the negative electrode of the aqueous zinc-ion battery with the polymer modification layer prepared in Example 1, ensuring that the coated side contacts the separator, placing a gasket, a spring piece, and a negative electrode case, and encapsulating the battery using a battery encapsulation machine to obtain a Cu / / VPANI@Zn asymmetric cell.

[0060] Using a pure copper (16 mm) electrode sheet as the positive electrode sheet of a button cell, placing a separator, dropping an electrolyte, and then placing the negative electrode of the aqueous zinc-ion battery with the polymer modification layer prepared in Comparative Example 1, ensuring that the coated side contacts the separator, placing a gasket, a spring piece, and a negative electrode case, and encapsulating the battery using a battery encapsulation machine to obtain a Cu / / PANI@Zn asymmetric cell.

[0061] Asymmetric cell with pure zinc electrode: The assembly method is the same as above, and the negative electrode sheet uses 99% pure zinc foil, marked as Cu / / Zn asymmetric cell.

[0062] Test results: The curve performance of the assembled Cu / / VPANI@Zn, Cu / / PANI@Zn, and Cu / / Zn asymmetric cells at 2 mA cm -2 and an areal capacity of 1 mAh cm -2 , with a cut-off voltage of 0.6 V is as follows Figure 4 shown. The experimental results prove that the Coulombic efficiency of Cu / / VPANI@Zn is 99.64% after 1000 cycles. It is higher than the cycle life and Coulombic efficiency of Cu / / PANI@Zn and Cu / / Zn asymmetric cells.

[0063] Application Example 3: Assembly of Full Cells

[0064] Preparation of manganese dioxide positive electrode material: Dissolve 0.768 g of MnSO 4 ·H 2O and 0.476 g of KMnO 4 。The obtained KMnO 4 solution was dropped into the MnSO 4 solution. After stirring for 30 minutes, the mixture was transferred to a polytetrafluoroethylene-lined high-pressure reactor and heated at 160 °C for 12 hours. After natural cooling, the resulting precipitate was centrifuged and washed with deionized water. Finally, the precipitate was dried in an oven at 80 °C to obtain MnO 2 。

[0065] Preparation of manganese dioxide positive electrode sheet: MnO 2 , acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone solution according to a mass ratio of 7:2:1, and were sufficiently mechanically stirred to prepare a slurry. The slurry was evenly scraped onto a titanium foil with a thickness of 30 μm and placed in a vacuum oven at 80 °C for 12 h. After taking it out, it was punched into a circular electrode sheet with a diameter of 12 mm.

[0066] The manganese dioxide positive electrode sheet was placed into the positive electrode case. Then, a separator was placed and electrolyte was dropped until the separator was completely wetted. Subsequently, the negative electrode sheet of the aqueous zinc ion battery with the polymer modification layer prepared in Example 1, a stainless steel gasket, a stainless steel spring piece and a negative electrode case were sequentially placed. Then, it was placed in a sealer for pressure packaging to obtain MnO 2 / / VPANI@Zn full battery, and the electrolyte was 2 M ZnSO 4 +0.2 M MnSO 4 。

[0067] The manganese dioxide positive electrode sheet was placed into the positive electrode case. Then, a separator was placed and electrolyte was dropped until the separator was completely wetted. Subsequently, the negative electrode sheet of the aqueous zinc ion battery with the polymer modification layer prepared in Comparative Example 1, a stainless steel gasket, a stainless steel spring piece and a negative electrode case were sequentially placed. Then, it was placed in a sealer for pressure packaging to obtain MnO 2 / / PANI@Zn full battery. The electrolyte was 2 M ZnSO 4 +0.2 M MnSO 4 。

[0068] Pure zinc electrode full battery: The assembly method was the same as above, except that 99% pure zinc foil was used for all the negative electrode sheets.

[0069] Test results: The assembled full batteries were charged and discharged cyclically at different currents. As Figure 5 shown, the specific capacity of the MnO 2 / / VPANI@Zn full battery at different current densities was higher than that of MnO 2 / / PANI@Zn and MnO 2 / / Zn.

[0070] The assembled full batteries were at 1 A g-1 The charge-discharge cycles are carried out at a current of Figure 6 As shown in 2 The specific capacity of the MnO 2 / / VPANI@Zn full cell after 1000 cycles is higher than that of MnO 2 / / PANI@Zn and MnO

[0071] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A negative electrode material for an aqueous zinc ion battery having a polymer modified layer, characterized in that: The aqueous zinc ion battery negative electrode material is obtained by dripping a polymer modified layer slurry on a zinc negative electrode and drying the polymer modified layer slurry; the polymer modified layer slurry comprises valine-doped polyaniline, a binder and an organic solvent.

2. The aqueous zinc ion battery negative electrode material of the polymer modified layer according to claim 1, characterized in that: The zinc negative electrode is a zinc foil with a thickness of 80-100 μm, and the structural formula of the valine-doped polyaniline is as follows:

3. The aqueous zinc ion battery negative electrode material of the polymer modified layer according to claim 1, characterized in that: The thickness of the polymer modified layer is 10-20 μm.

4. A method for preparing an aqueous zinc ion battery negative electrode material having a polymer modified layer as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: S1, adding aniline and valine into deionized water, mixing evenly, then dropping ammonium persulfate solution, stirring to react, and after the reaction is completed, filtering and drying to obtain valine-doped polyaniline; S2, adding the valine-doped polyaniline in step S1 into an organic solvent, then adding a binder, mixing evenly to obtain a polymer modified layer slurry, then drop-coating it on the zinc negative electrode, and drying to obtain the aqueous zinc ion battery negative electrode material with the polymer modified layer.

5. The preparation method according to claim 4, characterized in that: The concentration of the ammonium persulfate solution in step S1 is 200-250 g / L, and the mass ratio of the aniline, valine, deionized water, and ammonium persulfate solution is 1.5-2.5:0.5-0.7:70-100:24-26.

6. The preparation method according to claim 4, characterized in that: The dripping rate in step S1 is 1-1.5 mL / min.

7. The preparation method according to claim 4, characterized in that: The stirring reaction in step S1 is carried out at a temperature of 20-30° C. and for a time of 12-24 hours.

8. The preparation method according to claim 4, characterized in that: In step S2, the organic solvent is N-methylpyrrolidone or water, and the binder is polyvinylidene fluoride or carboxymethyl cellulose.

9. The preparation method according to claim 4, characterized in that: In step S2, the mass ratio of the binder to the valine-doped polyaniline is 1:2-9; the drying temperature is 60-80° C. and the drying time is 4-10 hours.

10. Use of an aqueous zinc ion battery negative electrode material having a polymer modified layer as claimed in any one of claims 1 to 3 in an aqueous zinc ion battery.

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