Metal powder negative electrode for aqueous metal-air battery, aqueous metal-air battery and method for manufacturing the same

Abstract

The application discloses a metal powder negative electrode for an aqueous metal-air battery, the aqueous metal-air battery and a preparation method thereof, and relates to the technical field of batteries. The metal powder negative electrode comprises a foamed nickel base body, a porous structure is formed in the foamed nickel base body, metal powder is filled in the porous structure, and a leakage prevention layer is arranged on the foamed nickel base body and used for preventing the metal powder from leaking out. The PPI of the foamed nickel base body is 10-110, and the diameter of the metal powder is 0.018mm-0.18mm. The metal powder negative electrode has good corrosion resistance, adjustability, processability and low cost, the contact between the metal powder and the current collector is stable, the corrosion and passivation of the metal powder negative electrode are greatly alleviated, and the utilization rate of the metal powder and the discharge performance of the metal-air battery are improved. The metal-air battery has excellent discharge capacity and discharge time under high current density.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water-based air battery, in particular to a metal powder negative electrode for water-based metal air battery, a water-based metal air battery and a preparation method thereof. BACKGROUND

[0002] Zinc-air battery has high theoretical energy density (1086 Wh kg -1 ), low cost, safety and environmental protection. The negative electrode material is abundant metal zinc in the crust. The positive active material is oxygen, which can be directly obtained from the air. Zinc-air battery has various types, including water-based battery, solid-state battery, flexible battery and button cell. Among them, water-based zinc-air battery is most suitable for large-scale energy storage field. Aluminum-air battery has an energy density of 8100 Wh kg -1 , higher than that of zinc-air battery, and the negative electrode material is metal aluminum, but the corrosion of aluminum negative electrode is more serious than that of zinc. The main configuration of aluminum-air battery is water-based battery and solid-state battery, which has a broader application prospect like zinc-air battery.

[0003] At present, the preparation method of metal powder-based metal air battery negative electrode is to mix metal powder, binder, conductive agent and corrosion inhibitor to form a metal paste, which is uniformly stirred and coated on the surface of the negative electrode current collector, dried and formed at a certain temperature, and then used after cooling. This method is complicated, the added binder is unstable in strong alkaline electrolyte, and the metal powder inevitably falls off from the current collector under long-term discharge state. In addition, the binder is not conductive, and the added corrosion inhibitor forms a corrosion-resistant film on the surface of the metal powder, which hinders the contact between the metal powder particles, resulting in unstable discharge under high current density. Some binders and corrosion inhibitors are high in cost and not suitable for large-scale commercial application. Therefore, the existing technology has defects and needs to be improved and developed. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a metal powder negative electrode for water-based metal air battery, a water-based metal air battery and a preparation method thereof, aiming at the above-mentioned defects of the prior art.

[0005] The technical solution adopted by the present application to solve the technical problem is as follows:

[0006] A metal powder negative electrode for water-based metal air battery, comprising:

[0007] A foamed nickel substrate with a porous structure formed inside;

[0008] Metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder, aluminum powder, magnesium powder and iron powder;

[0009] A leakage prevention layer is arranged on the nickel foam substrate and is used to prevent the metal powder from leaking out.

[0010] The PPI of the nickel foam substrate is 10-110, and the diameter of the metal powder is 0.018-0.18 mm.

[0011] Nickel foam is a material with a porous structure, which is composed of many small geometrically regular holes and connected channels, and exhibits a very large specific surface area and porosity. Therefore, nickel foam has the characteristics of high electrical conductivity, lightweight, uniform structure, good corrosion resistance, high porosity, etc. At present, the existing technology method uses a binder to connect the metal powder together to make a metal paste. The binder, such as polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose, etc., is not conductive, which will reduce the reactivity of the metal powder, and an electrically conductive agent such as carbon black, carbon nanotube, graphene, polyaniline, etc. material needs to be added additionally. The binder is unstable during long-time discharge, and the metal paste will fall off from the surface of the current collector. In the present application, the metal powder is dispersed in the pores of the nickel foam substrate, which can increase the contact area between the metal powder and the nickel foam substrate, and the three-dimensional channel structure of the nickel foam can stabilize the metal powder, without the need for additional binder and conductive agent, effectively preventing the metal powder from falling off.

[0012] The PPI of the nickel foam substrate is 10-110, and the PPI of the nickel foam refers to the number of pores per inch. The higher the PPI value, the smaller the pore size of the nickel foam substrate, and the more the number of pores. The lower the PPI value, the larger the pore size of the nickel foam substrate, and the fewer the number of pores. The pore size of the nickel foam substrate is 0.42-3.57 mm, and the pore size of the nickel foam substrate is larger than the diameter of the metal powder. Therefore, the nickel foam substrate with different pore sizes and the metal powder with different diameters are crucial to the dispersion state and reactivity of the metal powder.

[0013] When the nickel foam substrate with different pore sizes is loaded with the metal powder with the same diameter, from the perspective of the negative electrode reaction, first, the small-pore nickel foam substrate means that the single pore unit of the nickel foam substrate can accommodate less metal powder, and the contact area between the metal powder and the metal powder is smaller. On the contrary, the contact area between the metal powder and the electrolyte is larger, i.e. the metal powder is more fully in contact with the electrolyte, resulting in an accelerated reaction rate of the metal powder. Second, compared with the large-pore nickel foam substrate, the local OH - concentration in the small-pore nickel foam substrate is higher, and the reaction rate of the metal powder is faster.

[0014] From the perspective of passivation, the smaller the pore size of the nickel foam substrate, the greater the transmission resistance of the reaction products such as ZnO and electrolyte, making it difficult for ZnO to fall off the surface of the metal powder, reducing the conductivity of the negative electrode, leading to uneven stripping of the metal powder, reducing the discharge voltage and discharge time. But when the pore size of the nickel foam substrate increases to a certain extent, the metal powder will fall off from the pore size of the nickel foam substrate, reducing the utilization rate of the metal powder.

[0015] When the nickel foam substrate with the same pore size loads metal powder with different diameters, the particle size of the metal powder is too small, which increases the specific surface area of the metal powder and increases the corrosion rate of the metal powder; the particle size of the metal powder is too large, which makes it difficult for the metal powder to enter the gap of the nickel foam substrate, leading to uneven dispersion of the metal powder. The smaller the diameter of the metal powder, the more the number of metal powders that can be accommodated by a single pore unit of the nickel foam substrate, and the larger the contact area between the metal powders. On the contrary, the contact area between the metal powder and the electrolyte is smaller, that is, the metal powder and the electrolyte are less in contact, resulting in a decrease in the reaction rate of the metal powder.

[0016] Therefore, when the pore size of the nickel foam substrate is within a suitable range and the diameter of the metal powder is within a suitable range, that is, the PPI of the nickel foam substrate is 10-110, and the diameter of the metal powder is 0.018-0.18 mm, the comprehensive performance of the metal powder negative electrode is better, for example, the utilization rate of the metal powder is higher, the loading stability of the metal powder is higher, the discharge voltage is higher, the discharge time is longer, and the capacity is larger.

[0017] The mass ratio of the nickel foam substrate to the metal powder is 1:0.65-1.5. Too small mass of the metal powder will reduce the discharge time of the battery; too small mass of the metal powder will also make the metal powder more likely to overflow from the pores of the nickel foam.

[0018] The metal powder negative electrode for the aqueous metal-air battery, wherein when the metal powder is zinc powder, the PPI of the nickel foam substrate is 10-30; when the metal powder is aluminum powder, the PPI of the nickel foam is 20-75; the leak-proof layer is a waterproof and breathable film.

[0019] Preferably, when the metal powder is zinc powder, the PPI of the nickel foam substrate is 10-30, the pore size of the nickel foam substrate is 1.72-3.57 mm, and the aqueous zinc-air battery has good discharge effect. When the metal powder is aluminum powder, the PPI of the nickel foam substrate is 20-75, the pore size of the nickel foam substrate is 0.6-2.49 mm, and the aqueous aluminum-air battery has good discharge effect. The leak-proof layer can use a waterproof and breathable film, and the leak-proof layer can also use a grid layer.

[0020] An aqueous metal-air battery, comprising:

[0021] A housing having a window;

[0022] a positive electrode, disposed in the window of the casing;

[0023] a negative electrode, employing the metal powder negative electrode for aqueous metal-air battery according to any one of the preceding embodiments, and disposed in the casing away from the window;

[0024] an alkaline electrolyte, disposed in the casing;

[0025] wherein the positive electrode and the negative electrode are both disposed below the liquid level of the alkaline electrolyte.

[0026] Specifically, the positive electrode is an air positive electrode, which reacts with oxygen in the air, and the air enters the positive electrode from the window. The negative electrode is a metal powder negative electrode, and the electrolyte is an alkaline electrolyte. The metal powder reacts with the hydroxide of the alkaline electrolyte.

[0027] The aqueous metal-air battery, wherein the alkaline electrolyte comprises: a soluble acetate, a strong base, and water; wherein the concentration of the soluble acetate is 0.04 mol L -1 ~ 0.3 mol L -1 ; and the concentration of the strong base is 1 mol L -1 ~ 6 mol L -1 .

[0028] Specifically, the alkaline electrolyte comprises: a soluble acetate, a strong base, and water, the concentration of the soluble acetate is 0.04 mol L -1 ~ 0.3 mol L -1 ; and the concentration of the strong base is 1 mol L -1 ~ 6 mol L -1 . The soluble acetate can be zinc acetate Zn(AC)2, sodium acetate, potassium acetate, ammonium acetate, aluminum acetate, etc. The strong base can be KOH or NaOH. Preferably, the concentration of the soluble acetate is 0.2 mol L -1 . When the metal powder is zinc powder or iron powder, the concentration of the strong base is 6 mol L -1 , for example, the concentration of KOH is 6 mol L -1 . When the metal powder is aluminum powder or magnesium powder, the concentration of the strong base is 1 mol L -1 , for example, the concentration of KOH is 1 mol L -1 . When the metal powder is aluminum powder or magnesium powder, the alkaline electrolyte can also add corrosion inhibitors, such as glycerol, ethylene glycol, methanol, dimethyl sulfoxide, sulfolane, etc.

[0029] The aqueous metal-air battery, wherein the positive electrode comprises: a current collector, a waterproof and air-permeable conductive film, and a catalytic layer disposed in sequence; wherein the catalytic layer is made of a catalyst, a conductive carbon material, and polytetrafluoroethylene.

[0030] Specifically, the current collector is used to connect the catalytic layer and the external circuit. The waterproof, air-permeable and conductive film has a thickness of 0.3-1 mm. The waterproof, air-permeable and conductive film is used to build a three-phase interface, prevent the electrolyte from completely penetrating the catalyst of the catalytic layer and reducing the catalytic activity, and not hinder the entry of air.

[0031] The water-based metal-air battery, wherein the current collector extends out of the liquid level to form a positive electrode connecting part; the negative electrode is extended out of the liquid level to form a negative electrode connecting part.

[0032] Specifically, in order to facilitate the connection of the external circuit, the positive electrode connecting part is arranged on the current collector, and the negative electrode connecting part is arranged on the negative electrode. The positive electrode connecting part and the negative electrode connecting part are used to connect the external circuit. The waterproof, air-permeable and conductive film and the catalytic layer in the positive electrode are located below the liquid level of the alkaline electrolyte, and the positive electrode connecting part is located above the liquid level of the alkaline electrolyte. The negative electrode connecting part does not load metal powder.

[0033] The water-based metal-air battery, wherein the current collector is foamed nickel.

[0034] Specifically, the current collector can be foamed nickel.

[0035] A preparation method of the water-based metal-air battery according to any one of the preceding items, wherein the method comprises the steps of:

[0036] Preparation of the positive electrode, and assembling the positive electrode in the shell;

[0037] Preparation of the negative electrode, and assembling the negative electrode in the shell;

[0038] Injecting the alkaline electrolyte into the shell.

[0039] Specifically, the positive electrode, the negative electrode and the alkaline electrolyte can be prepared respectively, and then the positive electrode is assembled in the shell, the negative electrode is assembled in the shell, and the alkaline electrolyte is injected into the shell to form the water-based metal-air battery.

[0040] The preparation method of the water-based metal-air battery, wherein the preparation of the negative electrode and the assembling of the negative electrode in the shell comprises:

[0041] Cutting and bending the foamed nickel to obtain a foamed nickel base;

[0042] Connecting the leakage-proof layer to the foamed nickel base, and pouring metal powder to obtain the negative electrode;

[0043] Assembling the negative electrode in the shell.

[0044] Specifically, the nickel foam substrate is cut and bent from nickel foam, after bending, a part of the nickel foam substrate is loaded with metal powder as a loading part, and another part is connected to the external circuit as a negative electrode connecting part. The metal powder is poured into the loading part of the nickel foam substrate and shaken slightly to make the metal powder fully enter the loading part of the nickel foam substrate. The nickel foam substrate is L-shaped, in order to make the height of the loading part in the negative electrode and the height of the catalyst in the positive electrode substantially the same, a cushioning layer can be used to raise the nickel foam substrate. The cushioning layer can use polyethylene sponge.

[0045] The preparation method of the aqueous metal-air battery, wherein the preparation of the positive electrode and the assembly of the positive electrode in the shell comprises:

[0046] Mixing the catalyst, the conductive carbon material, the polytetrafluoroethylene and the volatile solvent and rolling into a catalytic layer;

[0047] Stacking the waterproof and breathable conductive film and the catalytic layer on the current collector in sequence to obtain the positive electrode;

[0048] Assembling the positive electrode in the shell.

[0049] Specifically, the preparation method of the catalytic layer is as follows: providing a slurry of the catalyst, the conductive carbon material, the polytetrafluoroethylene and anhydrous ethanol; placing the oxygen catalyst and the conductive carbon material in a mortar, adding dropwise the anhydrous ethanol and the slurry of the polytetrafluoroethylene to grind into a flaky shape, rolling into a thin layer, drying and cutting to obtain the catalytic layer. The conductive carbon material serves to enhance the electrical conductivity of the catalyst, the anhydrous ethanol serves to mix the catalyst and the conductive carbon material uniformly, and the slurry of the polytetrafluoroethylene serves to form a film of the catalyst and the conductive carbon material.

[0050] The nickel foam loaded metal powder negative electrode obtained by the preparation method is simple in preparation method, and the problems of corrosion, passivation of the metal powder and poor contact between the metal powder and the current collector are solved, so that the nickel foam loaded metal powder negative electrode is suitable for large-scale practical application. The metal-air battery has excellent discharge specific capacity and discharge time under high current density. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 is the optical photo of the nickel foam with different PPI in the embodiment of the application.

[0052] Figure 2 is the scanning electron microscope photo of the nickel foam with different PPI in the embodiment of the application.

[0053] Figure 3 is the scanning electron microscope photo of the 100-250 mesh (0.058-0.15 mm) zinc powder loaded on the nickel foam with different PPI in the embodiment of the application.

[0054] Figure 4Figure 1 is an optical photo of the preparation process of 30 PPI foam nickel loaded with 100-250 mesh (0.058-0.15 mm) zinc powder negative electrode and aqueous battery from different angles in the embodiments of the present application.

[0055] Figure 5 Figure 2 is a schematic diagram of a zinc-air battery in the embodiments of the present application.

[0056] Figure 6 Figure 3 is the discharge capacity of different PPI foam nickel loaded with 100-250 mesh (0.058-0.15 mm) zinc powder and zinc sheet at a current density of 100 mA / cm 2 in the embodiments of the present application.

[0057] Figure 7 Figure 4 is the utilization rate of zinc powder of different PPI foam nickel loaded with 100-250 mesh (0.058-0.15 mm) zinc powder at a current density of 100 mA / cm 2 in the embodiments of the present application.

[0058] Figure 8 Figure 5 is the discharge capacity of different PPI foam nickel loaded with 800 mesh (about 0.018 mm) zinc powder and zinc sheet at a current density of 100 mA / cm 2 in the embodiments of the present application.

[0059] Figure 9 Figure 6 is the utilization rate of zinc powder of different PPI foam nickel loaded with 800 mesh (about 0.018 mm) zinc powder at a current density of 100 mA / cm 2 in the embodiments of the present application.

[0060] Figure 10 Figure 7 is the concentration of hydroxyl ions on the surface of small pores in the finite element simulation in the embodiments of the present application.

[0061] Figure 11 Figure 8 is the concentration of hydroxyl ions on the surface of large pores in the finite element simulation in the embodiments of the present application.

[0062] Figure 12 Figure 9 is the hydrogen evolution potential and current density of different PPI foam nickel and 100-250 mesh (0.058-0.15 mm) zinc powder in the embodiments of the present application.

[0063] Figure 13 Figure 10 is a schematic diagram of the discharge principle of zinc powder loaded by different PPI foam nickel in the embodiments of the present application.

[0064] Figure 14 Figure 11 is a schematic diagram of the effect of different PPI foam nickel and different mesh zinc powder on the reaction in the embodiments of the present application.

[0065] Figure 15This refers to the discharge capacity of 30PPI foamed nickel and 100-250 mesh (0.058-0.15mm) zinc powder in electrolytes of different concentrations in the embodiments of the present invention.

[0066] Figure 16 This refers to the discharge time of zinc sheet and 1g of 100-250 mesh (0.058-0.15mm) zinc powder loaded with 30PPI nickel foam in the embodiment of the present invention.

[0067] Figure 17 In this embodiment of the invention, different PPI nickel-fed aluminum powder with 80 mesh (approximately 0.18 mm) loading is used at 5 mA / cm². 2 The discharge capacity at the current density.

[0068] Figure 18 In this embodiment of the invention, different PPI nickel-fed aluminum powder with 400 mesh (approximately 0.036 mm) loading is used at 5 mA / cm². 2 The discharge capacity at the current density.

[0069] Figure 19 This is a schematic diagram illustrating the effect of different PPI nickel foams and different mesh sizes of aluminum powder on the reaction in an embodiment of the present invention. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0071] Because zinc and aluminum have more negative reduction potentials than hydrogen, metallic zinc or aluminum are thermodynamically unstable in alkaline solutions, leading to hydrogen evolution corrosion (HEC) on the surface of the zinc or aluminum anode. HEC consumes electrons in the battery, reducing its energy conversion efficiency. Furthermore, HEC may also promote passivation of the zinc or aluminum anode surface, further affecting the battery's charge-discharge performance. The large specific surface area of ​​the metal powder exacerbates the corrosion phenomenon.

[0072] In the field of metal-air batteries based on metal powder, metal powder is usually mixed with binders and conductive agents, stirred to form a metal paste, and then applied to the surface of the current collector. Determining the optimal ratio of metal powder to binders and conductive agents requires extensive research and is quite complex. In strongly alkaline solutions, the binder exhibits poor stability, resulting in weak contact between the metal paste and the current collector. The use of binders and conductive agents increases costs, making them unsuitable for large-scale use.

[0073] This application uses a nickel foam matrix to support metal powder. The metal powder is confined and fixed by the nickel foam matrix. No binder or conductive agent is added to the metal powder. The utilization rate of the metal powder is high, making it suitable for large-scale use.

[0074] Example 1. (1) Cut the polyethylene sponge into 30 mm (length) * 20 mm (width) * 40 mm (thickness) and place it in the battery mold (the battery mold serves as the shell of the battery), keeping the upper surface of the polyethylene sponge and the center of the catalytic layer of the positive electrode (or the center of the window) at the same horizontal line. Cut the waterproof and breathable film (the waterproof and breathable film serves as the leak-proof layer) into 30 mm (length) * 20 mm (width) and place it on the upper surface of the polyethylene sponge, the function of the waterproof and breathable film is to prevent the zinc powder from falling down. Fold the 30PPI foam nickel substrate of 60 mm (length) * 30 mm (width) * 3 mm (thickness) so that the area of the zinc powder loaded foam nickel substrate (i.e. the loading part) is 30 mm (length) * 20 mm (width), and place it on the waterproof and breathable film, the foam nickel substrate not loaded with zinc powder (i.e. the negative electrode connecting part) is used to connect the external wire. Pour 1 g of 100-250 mesh (0.058-0.15 mm) zinc powder into the loading part of the 30PPI foam nickel substrate of 30 mm (length) * 20 mm (width) * 3 mm (thickness).

[0075] (2) Provide 60 mg of catalyst, 10 mg of conductive carbon material, 20 μL of polytetrafluoroethylene slurry, and 30 mL of anhydrous ethanol; place the oxygen catalyst and conductive carbon material in a mortar, add anhydrous ethanol and polytetrafluoroethylene slurry dropwise, grind for 30 min to form flakes, roll into a thin layer, dry at 60°C, and cut to obtain the catalytic layer.

[0076] Specifically, as shown in Figure 5 , the foam nickel is used as the current collector, the length and width dimensions of the current collector are 4 cm * 5 cm, the length and width dimensions of the waterproof and breathable conductive film are 3.5 cm * 3.5 cm, and the length and width dimensions of the catalytic layer are 1 cm * 1 cm. The thickness of the current collector is 1 mm. The current collector is used to connect the catalytic layer and the external circuit. The thickness of the waterproof and breathable conductive film is 0.7 mm. After the positive and negative electrodes are prepared respectively, pour 60 mL of 6 mol L -1 KOH and 0.2 mol L -1 Zn(AC)2 electrolyte to form a water-based zinc-air battery (denoted as 30 / 100-250, wherein 30 represents the PPI of the foam nickel substrate, and 100-250 represents the mesh number of the zinc powder), and start discharging. The preparation method of the catalyst is:

[0077] A mixture of 113 mg of Fe(N03)3*9H20 and 1.09 g of Zn(N03)2*6H20 in 30 mL of methanol, 1.314 g of dimethylimidazole in 15 mL of methanol, and the above solution were mixed, stirred at room temperature for 24 h, rinsed with methanol and N,N-dimethylformamide three times in sequence, and the obtained powder was dried at 70 °C overnight. Subsequently, the sample was placed in a tube furnace, kept at 900 °C for 3 h under a nitrogen atmosphere, and cooled to room temperature to obtain a black powder. 50 mg of the black powder and 0.705 g of ZnCl2were dissolved in 20 mL of deionized water, stirred for 1 h, and then the solution was placed in a 50 mL hydrothermal kettle, kept at 160 °C for 24 h, rinsed with deionized water and anhydrous ethanol three times in sequence, and the obtained powder was dried at 70 °C overnight. Subsequently, the sample was placed in a tube furnace, kept at 900 °C for 1 h under a nitrogen atmosphere, and cooled to room temperature to obtain a catalyst.

[0078] Example Two. Different from Example One, the zinc powder was loaded on a 75 PPI nickel foam substrate, and a water-based zinc-air battery was assembled (denoted as 75 / 100-250, wherein 75 represents the PPI of the nickel foam substrate, and 100-250 represents the mesh number of the zinc powder), and discharge was started.

[0079] Example Three. Different from Example One, the zinc powder was loaded on a 110 PPI nickel foam substrate, and a water-based zinc-air battery was assembled (denoted as 110 / 100-250, wherein 110 represents the PPI of the nickel foam substrate, and 100-250 represents the mesh number of the zinc powder), and discharge was started.

[0080] Example Four. Different from Example One, the zinc powder was loaded on a 20 PPI nickel foam substrate, and a water-based zinc-air battery was assembled (denoted as 20 / 100-250, wherein 20 represents the PPI of the nickel foam substrate, and 100-250 represents the mesh number of the zinc powder), and discharge was started.

[0081] Example Five. Different from Example One, the zinc powder was loaded on a 10 PPI nickel foam substrate, and a water-based zinc-air battery was assembled (denoted as 10 / 100-250, wherein 10 represents the PPI of the nickel foam substrate, and 100-250 represents the mesh number of the zinc powder), and discharge was started.

[0082] Example Six. (1) Polyethylene sponge was cut into 30 mm (length) * 20 mm (width) * 40 mm (thickness) and placed in a battery mold, keeping the upper surface of the polyethylene sponge and the center of the catalytic layer of the positive electrode at the same horizontal line. The waterproof and breathable film was cut into 30 mm (length) * 20 mm (width) and placed on the upper surface of the polyethylene sponge, and the waterproof and breathable film functioned to prevent the zinc powder from falling down. The 30PPI foam nickel substrate of 60 mm (length) * 30 mm (width) * 3 mm (thickness) was bent so that the foam nickel substrate loaded with zinc powder had an area of 30 mm (length) * 20 mm (width) and was placed on the waterproof and breathable film, and the foam nickel substrate not loaded with zinc powder was used to connect the external lead wire. 1 g of 800 mesh (about 0.018 mm) zinc powder was poured into the loading part of the 30PPI foam nickel substrate of 30 mm (length) * 20 mm (width) * 3 mm (thickness).

[0083] (2) 60 mg of catalyst, 10 mg of conductive carbon material, 20 μL of polytetrafluoroethylene slurry, and 30 mL of anhydrous ethanol were provided; the oxygen catalyst and the conductive carbon material were placed in a mortar, and the anhydrous ethanol and the polytetrafluoroethylene slurry were added dropwise and ground for 30 min to form flakes, which were rolled into a thin layer and dried at 60°C, and then cut to obtain the catalytic layer.

[0084] Specifically, the foam nickel was used as the current collector, the length and width dimensions of the current collector were 4 cm * 5 cm, the length and width dimensions of the waterproof and breathable conductive film were 3.5 cm * 3.5 cm, and the length and width dimensions of the catalytic layer were 1 cm * 1 cm. The thickness of the current collector was 1 mm. The current collector was used to connect the catalytic layer and the external circuit. The thickness of the waterproof and breathable film was 0.7 mm. After the positive and negative electrodes were prepared, 60 mL of an electrolyte of 6M KOH and 0.2M Zn(AC)2 was poured to form an aqueous zinc-air battery (denoted as 30 / 800, wherein 30 represents the PPI of the foam nickel substrate, and 800 represents the mesh number of the zinc powder), and discharging was started.

[0085] Example Seven. Different from Example Six, the zinc powder was loaded on a 75PPI foam nickel substrate, and an aqueous zinc-air battery was assembled (denoted as 75 / 800, wherein 75 represents the PPI of the foam nickel substrate, and 800 represents the mesh number of the zinc powder), and discharging was started.

[0086] Example Eight. Different from Example Six, the zinc powder was loaded on a 110PPI foam nickel substrate, and an aqueous zinc-air battery was assembled (denoted as 110 / 800, wherein 110 represents the PPI of the foam nickel substrate, and 800 represents the mesh number of the zinc powder), and discharging was started.

[0087] Example Nine. Different from Example Six, the zinc powder was loaded on a 20PPI foam nickel substrate, and an aqueous zinc-air battery was assembled (denoted as 20 / 800, wherein 20 represents the PPI of the foam nickel substrate, and 800 represents the mesh number of the zinc powder), and discharging was started.

[0088] Example Ten. Different from Example Six, the zinc powder is filled in the 10 PPI nickel foam substrate, and the water-based zinc-air battery is assembled (denoted as 10 / 800, wherein 10 represents the PPI of the nickel foam substrate, and 800 represents the mesh number of the zinc powder), and the discharge is started.

[0089] Example Eleven. Different from Example One, the electrolyte is 60 mL of 4 mol L -1 KOH and 0.2 mol L -1 Zn(AC)2, and the battery is assembled and the discharge is started.

[0090] Example Twelve. Different from Example One, the electrolyte is 60 mL of 6 mol L -1 KOH and 0.1 mol L -1 Zn(AC)2, and the battery is assembled and the discharge is started.

[0091] Example Thirteen. Different from Example One, the electrolyte is 60 mL of 6 mol L -1 KOH and 0.3 mol L -1 Zn(AC)2, and the battery is assembled and the discharge is started.

[0092] Comparative Example. Different from Example One, 1 g of high-purity zinc sheet (purity 99.999%, thickness 0.3 mm) is placed in the battery mold, and the battery is assembled (denoted as zinc sheet), and the discharge is started.

[0093] As shown in FIG. 1, with the decrease of the PPI of the nickel foam, the pore size of the nickel foam substrate increases. Figure 1

[0094] As shown in FIG. 2, the nickel foam substrate is a three-dimensional network structure, with the decrease of the PPI of the nickel foam, the pore size of the nickel foam substrate increases, and the number of the skeleton of the nickel foam substrate decreases. The large pore size of the nickel foam substrate helps to increase the transmission and mass transfer efficiency of the ions in the pore. The pore size of the 110 PPI nickel foam substrate is 0.4 to 0.5 mm, the pore size of the 75 PPI nickel foam substrate is about 0.6 mm, the pore size of the 30 PPI nickel foam substrate is about 1.72 mm, the pore size of the 20 PPI nickel foam substrate is about 2.49 mm, and the pore size of the 10 PPI nickel foam substrate is about 3.57 mm. Figure 2

[0095] As shown in FIG. 3, the 100-250 mesh (0.058-0.15 mm) zinc powder is filled in the interstices of the skeleton of the nickel foam substrate with different PPI, and a small part of the zinc powder is on the skeleton of the nickel foam substrate. Figure 3

[0096] Figure 4 ​​​​As shown in Figure (a), the polyethylene sponge is cut into 30mm (length) * 20mm (width) * 40mm (thickness) pieces and placed in the battery mold, ensuring that the upper surface of the polyethylene sponge and the center of the positive electrode catalyst layer are on the same horizontal line. Figure 4 As shown in Figure (b), the waterproof and breathable membrane is cut to 30mm (length) * 20mm (width) and placed on the upper surface of the polyethylene sponge. The function of the waterproof and breathable membrane is to prevent the zinc powder from falling downwards. Figure 4 As shown in Figure (c), a 60mm (length) * 30mm (width) * 3mm (thickness) 30PPI nickel foam substrate is bent so that the zinc powder-loaded nickel foam substrate has an area of ​​30mm (length) * 20mm (width) and is placed on a waterproof and breathable membrane. The unloaded nickel foam substrate is used to connect external wires. Figure 4 As shown in Figure (d), 1g of 100-250 mesh (0.058-0.15mm) zinc powder is poured into a 30mm (length) * 20mm (width) * 3mm (thickness) foam nickel matrix. Figure 4 (e) diagram and Figure 4 Image (f) shows real photos of an aqueous zinc-air battery taken from different angles.

[0097] like Figure 6 As shown, the theoretical battery capacity of 1g of zinc is 820mAh. However, due to corrosion and passivation side reactions of zinc sheets or zinc powder, the actual battery capacity of zinc sheets or zinc powder is lower than the theoretical battery capacity. The following explanation uses actual battery capacities. The capacity of the 1g zinc sheet battery in the comparative example is 761mAh; the capacity of the 1g zinc powder battery in Example 1 is 611mAh, reaching 80.3% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 2 is 343.7mAh, reaching 45.2% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 3 is 241mAh, reaching 31.7% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 4 is 520.7mAh, reaching 68.4% of the zinc sheet battery capacity; and the capacity of the zinc powder battery in Example 5 is 494mAh, reaching 65% of the zinc sheet battery capacity. It can be observed that as the PPI of the nickel foam gradually decreases from 110 to 30, the pore size of the nickel foam matrix gradually increases, and the capacity of the zinc powder gradually increases. As the PPI of nickel foam gradually decreases from 30 to 10, the pore size of the nickel foam matrix continues to increase, while the capacity of zinc powder gradually decreases. The discharge capacity of batteries formed by nickel foam matrices with PPI of 30, 20, and 10 is generally greater than that of batteries formed by nickel foam matrices with PPI of 75 and 110.

[0098] like Figure 7As shown, the zinc powder utilization rate was 75% in Example 1, 42% in Example 2, 29.4% in Example 3, 63.5% in Example 4, and 60.2% in Example 5. As the PPI of the nickel foam gradually decreased from 110 to 30, the pore size of the nickel foam matrix gradually increased, and the zinc powder utilization rate gradually increased. Conversely, as the PPI of the nickel foam gradually decreased from 30 to 10, the pore size of the nickel foam matrix continued to increase, and the zinc powder utilization rate gradually decreased. The zinc powder utilization rates of batteries formed from nickel foam matrices with PPIs of 30, 20, and 10 were generally higher than those formed from nickel foam matrices with PPIs of 75 and 110.

[0099] like Figure 8 As shown, the capacity of the 1g zinc sheet battery in the comparative example is 761mAh; the capacity of the zinc powder battery in Example 6 is 505mAh, reaching 66.4% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 7 is 445mAh, reaching 58.5% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 8 is 357mAh / g, reaching 46.9% of the zinc sheet battery capacity. The capacity of the zinc powder battery in Example 9 is 556mAh, reaching 67.8% of the zinc sheet battery capacity; the capacity of the zinc powder battery in Example 10 is 516.6mAh, reaching 63% of the zinc sheet battery capacity. It can be observed that as the PPI of the nickel foam gradually decreases from 110 to 20, the pore size of the nickel foam matrix gradually increases, and the battery capacity of the zinc powder gradually increases. As the PPI of nickel foam decreases from 20 to 10, the pore size of the nickel foam matrix continues to increase, and the battery capacity of zinc powder decreases. The discharge capacity of batteries formed by nickel foam matrices with 30 PPI, 20 PPI, and 10 PPI is generally greater than that of batteries formed by nickel foam matrices with 75 PPI and 110 PPI.

[0100] like Figure 9 As shown, the zinc powder utilization rate was 61.6% in Example 6, 54.3% in Example 7, 43.5% in Example 8, 67.9% in Example 9, and 63% in Example 10. As the PPI of the nickel foam gradually decreased from 110 to 20, the pore size of the nickel foam matrix gradually increased, and the zinc powder utilization rate gradually increased. As the PPI of the nickel foam decreased from 20 to 10, the pore size of the nickel foam matrix continued to increase, and the zinc powder utilization rate decreased. The zinc powder utilization rates of nickel foam matrices with PPIs of 30, 20, and 10 were generally greater than those of nickel foam matrices with PPIs of 75 and 110.

[0101] like Figure 10 and Figure 11As shown, the finite element method (FEM) simulation of hydroxide ion concentrations on the surfaces of small and large pores was performed. For the same volume of nickel foam matrix, small pores correspond to a greater number of pores, while large pores correspond to a smaller number of pores. The FEM simulation only studies the effect of pore size on hydroxide ion concentration in the pores of the nickel foam matrix; for ease of modeling, the shapes of both small and large pores are set as triangles and rectangles, respectively. Figure 10 The model displays a total of 14 holes, four on the top and bottom surfaces and six in the center. The hydroxide ion concentration on the surface of the sphere is 5 × 10⁻⁶. 4 molcm -3 . Figure 11 The display shows a total of 9 large pores, with three pores each on the upper and lower surfaces of the sphere, and three pores in the middle. The hydroxide ion concentration on the surface of the sphere is 4 × 10⁻⁶. 4 molcm -3 As the PPI of nickel foam decreases, the pore size of the nickel foam matrix increases, and the concentration of hydroxide ions on the pore surface gradually decreases.

[0102] The reaction equation for an alkaline zinc-air battery is as follows: Under alkaline conditions, the reaction process at the zinc negative electrode is as follows:

[0103]

[0104] The formation reaction of the zinc negative electrode passivation layer under alkaline conditions:

[0105]

[0106] (1) is the dissolution reaction of the zinc anode under alkaline conditions, and (2) and (3) are the reactions that form the passivation layer.

[0107] Under alkaline conditions, a conjugate corrosion reaction occurs on the zinc anode:

[0108]

[0109] 2H2O+2e - →2OH - +H2↑(4).

[0110] Under alkaline conditions, the positive electrode reaction process is as follows:

[0111]

[0112] like Figure 13 As shown, during the discharge process of a zinc-air battery, as indicated by reactions (1) to (3) at the negative electrode, the zinc negative electrode loses electrons and becomes Zn(OH)4. 2- Zn(OH)4 2-ZnO after saturation in the electrolyte, which is an important part of the normal operation of zinc-air batteries in alkaline environment. Oxygen at the positive electrode gets electrons from the external circuit, which are lost by zinc, and is reduced to hydroxyl ions. The dissolution and passivation behavior of the zinc anode plays an important role in the performance of zinc-air batteries. A fast dissolving zinc anode can provide a large current for the battery, however, a high passivation rate of the zinc anode greatly shortens the battery life. A moderate inhibition of the passivation rate of the zinc anode while maintaining the activity of the zinc anode can improve the discharge performance of the battery. Therefore, it is necessary to promote reaction (1) and inhibit reaction (2) and reaction (3).

[0113] Reaction (4) is a hydrogen evolution corrosion reaction, and reactions (1), (3) and (4) form a conjugate corrosion reaction. The electrons formed on the zinc surface by reaction (1) and the active water molecules formed on the zinc surface by reaction (3) can react with reaction (4) and release hydrogen. Of course, isolated water molecules in the electrolyte can also react with reaction (4) on the zinc surface. Reaction (4) consumes the electrons obtained by reaction (1), reduces the energy conversion efficiency of the battery, and inhibiting reaction (4) can improve the discharge performance of the battery.

[0114] The influencing factors of reaction (1) are the activity of Zn and the concentration of hydroxyl ions c[OH - ]. The smaller the particle size of the zinc powder, the higher the activity of Zn, and reaction (1) can be promoted; the smaller the pore size of the foam nickel substrate, the higher the concentration of hydroxyl ions, and reaction (1) can be promoted. Conversely, the larger the particle size of the zinc powder, the lower the activity of Zn, and reaction (1) can be inhibited; the larger the pore size of the foam nickel substrate, the lower the concentration of hydroxyl ions, and reaction (1) can be inhibited.

[0115] The influencing factors of reactions (2) and (3) are the concentration of Zn(OH)4 2- c[Zn(OH)4 2- ]. The larger the pore size of the foam nickel substrate, the faster the mass transfer of Zn(OH)4 2- , the lower c[Zn(OH)4 2- ], and the less likely the passivation layer to be generated, and reactions (2) and (3) can be inhibited; the larger the particle size of the zinc powder, the lower c[Zn(OH)4 2- ], and the less likely the passivation layer to be generated, and reactions (2) and (3) can be inhibited. Conversely, the smaller the pore size of the foam nickel substrate, the slower the mass transfer of Zn(OH)4 2- , the higher c[Zn(OH)4 2- ], and the more likely the passivation layer to be generated, and reactions (2) and (3) can be promoted; the smaller the particle size of the zinc powder, the higher c[Zn(OH)4 2-The higher the concentration of OH", the easier the passivation layer is generated, and the reactions (2) and (3) can be promoted.

[0116] The reaction (4) is related to the reaction (1) and the reaction (3). The electrons on the surface of the zinc negative electrode obtained in the reaction (1) and the active water molecules on the surface of the zinc negative electrode obtained in the reaction (3) are prone to the reaction (4) to obtain hydrogen. Therefore, the reaction (1) and the reaction (3) are inhibited, and the reaction (4) is inhibited.

[0117] In order to improve the discharge performance of the battery, the reaction (1) needs to be promoted and the reactions (2) to (4) need to be inhibited. The particle size of the zinc powder has opposite effects on the reactions (1) and (2) to (4), and the pore size of the foamed nickel matrix has opposite effects on the reactions (1) and (2) to (4). Therefore, when the particle size of the zinc powder is in a suitable particle size range and the pore size of the foamed nickel matrix is in a suitable pore size range, it is beneficial to promote the reaction (1) and inhibit the reactions (2) to (4).

[0118] As shown in Figure 14 , when the particle size of the zinc powder is in a suitable particle size range and the pore size of the foamed nickel matrix is in a suitable pore size range, and the small-pore foamed nickel is matched with the small-particle-size zinc powder, the reaction (1) is mainly promoted. When the particle size of the zinc powder is in a suitable particle size range and the pore size of the foamed nickel matrix is in a suitable pore size range, and the large-pore foamed nickel is matched with the large-particle-size zinc powder, the reactions (2) to (4) are mainly inhibited. When the particle size of the zinc powder is in a suitable particle size range and the pore size of the foamed nickel matrix is in a suitable pore size range, and the small-pore foamed nickel is matched with the large-particle-size zinc powder, the reaction (1) is promoted and the reactions (2) to (4) are inhibited. When the particle size of the zinc powder is in a suitable particle size range and the pore size of the foamed nickel matrix is in a suitable pore size range, and the large-pore foamed nickel is matched with the small-particle-size zinc powder, the reaction (1) is promoted and the reactions (2) to (4) are inhibited.

[0119] Specifically, first, when the OH - concentration near the zinc powder negative electrode is increased or the particle size of the zinc powder is reduced, Zn is more prone to react with OH - to generate Zn(OH)4 2- . At the same time, the increase of Zn(OH)4 2- directly leads to the increase of Zn(OH)2 and ZnO, that is, the increase of the OH - concentration near the zinc powder negative electrode and the reduction of the particle size of the zinc powder increase the reactivity of zinc while accelerating the passivation of the zinc powder. Second, the Zn(OH)2 and ZnO passivation films generated after the dissolution of zinc prevent the further oxidation of the zinc powder to a certain extent, and have the effect of inhibiting the dissolution of zinc. However, ZnO has a high OH -Zn is easily dissolved by the electrolyte, leading to the detachment of Zn(OH)2and ZnO passivation films from the surface of the zinc powder, exposing active Zn, and thus further exacerbating the passivation of the zinc powder. In the process of detachment, the Zn(OH)2and ZnO passivation films carry a portion of unreacted zinc powder into the electrolyte, reducing the utilization of the zinc powder, leading to unstable discharge voltage and fluctuation of the battery, and reducing the discharge capacity of the battery. The passivation films also hinder the contact between the zinc powder and the electrolyte and the contact between the zinc powders, leading to inhibition of the electrochemical activity of the zinc powder.

[0120] Secondly, the standard reduction potential of zinc / zinc oxide (-1.26 V vs. SHE) is lower than the potential of the hydrogen evolution reaction (-0.83 V vs. SHE), so zinc is thermodynamically unstable in water or aqueous solution. Oxidation of zinc and reduction of hydrogen ions in the electrolyte near the zinc constitute a micro-battery. As shown in the conjugate reaction process, i.e., reactions (1), (3), and (4), zinc dissolution produces electrons, Zn(OH)2dehydrates, and water evolves hydrogen at the cathode, forming a conjugate corrosion reaction. When the ionized hydrogen ions in the electrolyte solution obtain sufficient electrons released by the oxidation of zinc, they combine to form H2, which generally occurs on the surface of the zinc negative electrode. The general steps of the cathodic reduction reaction of H2O molecules on the surface of zinc are as follows: H2O molecules that evolve hydrogen on the cathode migrate to the surface of zinc, H2O molecules obtain electrons on the surface of zinc to generate H atoms adsorbed on the surface of zinc, H atoms recombine on the surface of zinc to generate H2molecules, and H2molecules desorb to form H2gas bubbles.

[0121] Since H2is continuously generated and evolves from the electrolyte solution to the air, the activity of the product of reaction (4) in the electrolyte solution is low. From the perspective of kinetics, more Zn and OH - react to generate more electrons, and a large number of electrons combine with H2O on the surface of zinc to generate more H2. The evolved hydrogen gas also isolates the zinc powder and the electrolyte, increases the transfer impedance of Zn(OH)4 2- and OH - , and reduces the capacity and voltage of the battery.

[0122] Thirdly, the pore size of the foamed nickel is large and the particle size of the zinc powder is small, which is not conducive to the fixation of the zinc powder by the foamed nickel, and a portion of the zinc powder may fall off from the pores of the foamed nickel matrix into the electrolyte, i.e., when the pore size of the foamed nickel matrix increases to a certain extent, the number of three-dimensional skeletons of the foamed nickel matrix decreases, which weakens the confinement of the foamed nickel matrix on the zinc powder, thus reducing the discharge capacity and utilization of the zinc powder.

[0123] For example, Figure 12As shown, as the PPI of nickel foam gradually decreased from 110 to 30, the hydrogen evolution potential of zinc powder shifted significantly to the negative, and the hydrogen evolution current decreased significantly. When the PPI of nickel foam gradually decreased from 30 to 10, the hydrogen evolution potential of zinc powder shifted slightly to the negative, and the hydrogen evolution current decreased slightly. This indicates that when the PPI of the nickel foam matrix decreases to a certain value, that is, when the pore size of the nickel foam matrix increases to a certain value, the change in the pore size of the nickel foam matrix has no significant effect on the hydrogen evolution of zinc powder. In other words, when the pore size is small (75 / 100-250, 110 / 100-250), hydrogen evolution is more severe and will promote the reaction to a large extent (4); when the pore size is large (30 / 100-250, 20 / 100-250, 10 / 100-250), hydrogen evolution is less severe and will promote the reaction to a certain extent (1), specifically as follows Figure 14 As shown.

[0124] like Figure 13 As shown, when zinc powder of different particle sizes is loaded onto nickel foam substrates of the same volume but different pore sizes, the hydroxide ion concentration in the pore units of the large-pore nickel foam substrate is lower. Although it inhibits reaction (1) to some extent, it can also inhibit reactions (2) to (4) to some extent. While the small-pore size promotes reaction (1) to some extent, as discussed above, it also promotes reactions (2) to (4) while promoting reaction (1). As the discharge proceeds, the small-pore size leads to more severe passivation of zinc powder and hydrogen evolution. The large-pore size of the nickel foam substrate means that the number of zinc powder particles that can be accommodated in a single pore unit of the nickel foam substrate is greater, resulting in a larger contact area between zinc powder particles in each pore and a smaller contact area between zinc powder particles and electrolyte. This can inhibit reaction (1) and also inhibit reactions (2) to (4) to some extent. Compared with large-particle-size zinc powder, small-particle-size zinc powder has a larger specific surface area, higher activity, and is more likely to promote reaction (1) and simultaneously promote reactions (2) to (4). Therefore, zinc powders of different particle sizes all have a corresponding optimal local hydroxide ion concentration.

[0125] For example, the local hydroxide ion concentrations in the pore sizes of nickel foam matrices with 110 PPI, 75 PPI, 30 PPI, 20 PPI, and 10 PPI are c[OH] , ... - ] 110 c[OH] - ] 75 c[OH] - ] 30 c[OH] - ] 20 c[OH] - ] 10 , where c[OH - ] 110 >c[OH - ] 75 >c[OH- ] 30 c[OH - ] 20 c[OH - ] 10 (alkaline electrolyte, the local concentration of hydroxyl ions in the pores is different due to the different pore sizes of the foamed nickel matrix), the 100-250 mesh (0.058-0.15 mm) zinc powder is most suitable for the concentration of c[OH - ] 30 (30 / 100-250 sample, as shown in Figure 6 , the effect is best), c[OH - ] 110 and the local concentration of hydroxyl ions c[OH - ] 75 is higher, which will exacerbate the passivation and hydrogen evolution corrosion of zinc powder (as shown in Figure 6 , the effect of 110 / 100-250 sample and 75 / 100-250 sample is poor), the pore size of 20PPI and 10PPI is larger, which will reduce the activity of zinc powder (as shown in Figure 6 , the effect of 20 / 100-250 sample and 10 / 100-250 sample is slightly worse). The 800 mesh (0.058-0.15 mm) zinc powder is most suitable for the concentration of c[OH - ] 20 (20 / 800 sample, as shown in Figure 8 , the effect is best), c[OH - ] 110 , c[OH - ] 75 and c[OH - ] 30 is higher, which will exacerbate the corrosion of zinc powder (as shown in Figure 8 , the effect of 110 / 800 sample and 75 / 800 sample is poor, and the effect of 30 / 800 sample is slightly worse), the pore size of 10PPI is larger, which will reduce the activity of zinc powder (as shown in Figure 8 , the effect of 10 / 800 sample is slightly worse).

[0126] Therefore, under the premise of using 6M KOH and 0.2M Zn(AC)2 electrolyte, by using foamed nickel matrix with different pore sizes, the local concentration of hydroxyl ions near zinc powder with different mesh can be adjusted to effectively reduce the corrosion of zinc powder and obtain the optimal discharge capacity and zinc powder utilization rate.

[0127] In comparison with the method of configuring zinc powder into zinc paste which is widely used at present, the present application does not need to add binder and conductive agent, does not need long time stirring and even drying steps, is simple to operate and has low cost. In strong alkaline electrolyte, zinc paste will fall off from the surface of current collector during long time and large current discharge process, which reduces the utilization of zinc powder and the capacity of battery. In addition, the binder is not conductive, which hinders the contact between zinc powder particles and inevitably hinders the transport of zinc ions, reducing the activity of zinc powder. The larger the current density is, the higher the requirement of battery discharge on the ion transport between zinc powder particles is, therefore, the method of configuring zinc powder into zinc paste cannot meet the requirement of large discharge current density on good contact between zinc powder particles, which will lead to unstable discharge voltage of battery.

[0128] As shown in Figure 15 , the discharge capacity and average discharge voltage of battery in electrolyte of 6M KOH and 0.2M Zn(AC)2 are superior to those in electrolyte of 4M KOH and 0.2M Zn(AC)2. At present, the electrolyte of alkaline zinc-air battery is generally 6M KOH and 0.2M Zn(AC)2, which comprehensively considers the conductivity of electrolyte and the activity of positive and negative electrodes. The low concentration of hydroxyl ions described in the foregoing will inhibit the corrosion of zinc powder, but too low concentration of hydroxyl ions such as 4M KOH will reduce the conductivity of electrolyte and the dissolution of zinc oxide generated by negative electrode, so that zinc powder cannot contact with electrolyte. In addition, too low concentration of hydroxyl ions will reduce the activity of oxygen reduction at positive electrode.

[0129] As shown in Figure 16 , the discharge capacity of zinc powder is tested by constant current discharge test, and the test conditions are discharge for 30 min and rest for 30 min. The working time of 30PPI nickel foam substrate, 250mm, 1g zinc powder is 10.7h, and the working time of 1g zinc sheet is 13.3h, and the working time of zinc powder reaches 81% of that of zinc sheet.

[0130] Figure 16 The zinc sheet used is special for laboratory test, and the thickness of experimental grade zinc sheet is only 0.3mm, and the purity is 99.999%. The test scale is small. When zinc-air battery is used in large scale, the amount of application grade zinc sheet used as negative electrode can reach kilogram level. If the thickness of application grade zinc sheet needs to be kept at about 0.3mm, it will increase the manufacturing cost greatly. However, the increase of thickness of application grade zinc sheet will make it more prone to passivation, that is, the generation of dense zinc oxide with poor conductivity covering the surface of application grade zinc sheet will lead to the internal part of zinc sheet unable to contact with electrolyte and unable to continue to participate in the reaction, which will significantly reduce the utilization of application grade zinc sheet and the discharge capacity of battery. The increase of the number of replacement of application grade zinc sheet will also increase the process of processing the oxide film on the surface of application grade zinc sheet.

[0131] The stability of the negative electrode during operation and the convenience of use are required in large-scale applications. The application-level zinc sheet, which simultaneously serves as a negative electrode current collector and an active material, has the following problems: (1) If the external connecting wire connected to the application-level zinc sheet is immersed in the electrolyte, the application-level zinc sheet is consumed in large quantities as the reaction proceeds, and there are serious problems such as perforation and shedding, which can cause unstable connection between the application-level zinc sheet and the external circuit, which can cause the battery to fail, and even cause safety problems. (2) If a part of the application-level zinc sheet is placed above the electrolyte to connect the external circuit, this will reduce the use efficiency of this part of the application-level zinc sheet. Moreover, the application-level zinc sheet connected to the external circuit is inevitably corroded, which makes it difficult to accurately determine the actual reaction quality of the application-level zinc sheet, making it difficult to calculate the energy density of the battery.

[0132] In large-scale applications, compared with the application-level zinc sheet, zinc powder has the advantages of low cost, adjustability and processability, and the mass of zinc powder participating in the reaction can be accurately determined, and it is expected to achieve the same discharge capacity as the application-level zinc sheet or even exceed the application-level zinc sheet. In addition, the zinc powder is loaded in the pores of the foam nickel matrix, i.e., the negative active material and the current collector are separated, the three-dimensional porous structure of the foam nickel matrix maintains the contact area between the zinc powder and the current collector, and the discharge stability and safety of the battery are increased. After the zinc powder is completely reacted, only new zinc powder needs to be poured into the foam nickel matrix, which is convenient to operate and saves time. In summary, compared with the zinc paste and zinc sheet, the zinc powder negative electrode for aqueous zinc-air batteries, the aqueous zinc-air battery and the preparation method thereof of the present application are more suitable for large-scale practical applications.

[0133] Example Fourteen. (1) Cut the polyethylene sponge into 30 mm (length) * 20 mm (width) * 40 mm (thickness) and place it in the battery mold (the battery mold serves as the shell of the battery). The upper surface of the polyethylene sponge and the center of the catalytic layer of the positive electrode (or the center of the window) are kept on the same horizontal line. Cut the waterproof and breathable film (the waterproof and breathable film serves as the leak-proof layer) into 30 mm (length) * 20 mm (width) and place it on the upper surface of the polyethylene sponge. The function of the waterproof and breathable film is to prevent the aluminum powder from falling down. Fold the 60 mm (length) * 30 mm (width) * 3 mm (thickness) 30PPI foam nickel matrix so that the area of the aluminum powder loaded foam nickel matrix (i.e., the loading part) is 30 mm (length) * 20 mm (width), and place it on the waterproof and breathable film. The foam nickel matrix without aluminum powder (i.e., the negative electrode connecting part) is used to connect the external wire. Pour 0.2 g of 80 mesh (0.18 mm) aluminum powder into the loading part of the 30 mm (length) * 20 mm (width) * 3 mm (thickness) 30PPI foam nickel matrix.

[0134] (2) Provide 60 mg of catalyst, 10 mg of conductive carbon material, 20 μL of polyvinylidene fluoride slurry and 30 mL of anhydrous ethanol; place the oxygen catalyst and conductive carbon material in a mortar, add anhydrous ethanol and polyvinylidene fluoride slurry and grind for 30 min until it becomes a sheet, roll it into a thin layer, dry it at 60 °C and cut it to obtain the catalyst layer.

[0135] Specifically, such as Figure 5 As shown, nickel foam is used as the current collector, with dimensions of 4cm x 5cm. The waterproof, breathable, and conductive membrane measures 3.5cm x 3.5cm, and the catalyst layer measures 1cm x 1cm. The current collector is 1mm thick and is used to connect the catalyst layer and the external circuit. The waterproof, breathable, and conductive membrane is 0.7mm thick. After the positive and negative electrodes are prepared, 48mL of 1mol L... -1 KOH, 12 mL glycerol and 0.04 mol L -1 The Zn(AC)2 electrolyte forms an aqueous aluminum-air battery (denoted as 30 / 80, where 30 represents the PPI of the nickel foam matrix and 80 is the mesh size of the aluminum powder), and discharge begins. The catalyst is the self-made catalyst mentioned above.

[0136] Example 15. Unlike Example 14, the aluminum powder was loaded onto a 10 PPI nickel foam matrix, assembled into an aqueous aluminum-air battery (denoted as 10 / 80, where 10 represents the PPI of the nickel foam matrix and 80 is the mesh size of the aluminum powder), and started discharging.

[0137] Example 16. Unlike Example 14, the aluminum powder was loaded onto a 20 PPI nickel foam matrix, assembled into an aqueous aluminum-air battery (denoted as 20 / 80, where 20 represents the PPI of the nickel foam matrix and 80 is the mesh size of the aluminum powder), and started discharging.

[0138] Example 17. Unlike Example 14, the aluminum powder was loaded onto a 75 PPI nickel foam matrix, assembled into an aqueous aluminum-air battery (denoted as 75 / 80, where 75 represents the PPI of the nickel foam matrix and 80 is the mesh size of the aluminum powder), and started discharging.

[0139] Example 18. Unlike Example 14, the aluminum powder was loaded onto a 110 PPI nickel foam matrix, which was assembled into an aqueous aluminum-air battery (denoted as 110 / 80, where 110 represents the PPI of the nickel foam matrix and 80 is the mesh size of the aluminum powder), and then started discharging.

[0140] Example 19. (1) Cut a polyethylene sponge into 30mm (length) * 20mm (width) * 40mm (thickness) pieces and place them in a battery mold (the battery mold serves as the battery casing), keeping the upper surface of the polyethylene sponge and the center (or the center of the window) of the positive electrode catalyst layer at the same horizontal level. Cut a waterproof and breathable membrane (the waterproof and breathable membrane serves as a leak-proof layer) into 30mm (length) * 20mm (width) pieces and place it on the upper surface of the polyethylene sponge. The function of the waterproof and breathable membrane is to prevent aluminum powder from falling downwards. Bend a 60mm (length) * 30mm (width) * 3mm (thickness) 30PPI foam nickel substrate so that the area of ​​the aluminum powder-loaded foam nickel substrate (i.e., the load part) is 30mm (length) * 20mm (width), and place it on the waterproof and breathable membrane. The non-aluminum powder-loaded foam nickel substrate (i.e., the negative electrode connection part) is used to connect external wires. 0.2g of 400-mesh (0.036mm) aluminum powder was poured into the support portion of a 30mm (length) * 20mm (width) * 3mm (thickness) foam nickel matrix.

[0141] (2) Provide 60 mg of catalyst, 10 mg of conductive carbon material, 20 μL of polyvinylidene fluoride slurry and 30 mL of anhydrous ethanol; place the oxygen catalyst and conductive carbon material in a mortar, add anhydrous ethanol and polyvinylidene fluoride slurry and grind for 30 min until it becomes a sheet, roll it into a thin layer, dry it at 60 °C and cut it to obtain the catalyst layer.

[0142] Specifically, such as Figure 5 As shown, nickel foam is used as the current collector, with dimensions of 4cm x 5cm. The waterproof, breathable, and conductive membrane measures 3.5cm x 3.5cm, and the catalyst layer measures 1cm x 1cm. The current collector is 1mm thick and is used to connect the catalyst layer and the external circuit. The waterproof, breathable, and conductive membrane is 0.7mm thick. After the positive and negative electrodes are prepared, 48mL of 1mol L... -1 KOH, 12 mL glycerol and 0.04 mol L -1 The Zn(AC)2 electrolyte forms an aqueous aluminum-air battery (denoted as 30 / 400, where 30 represents the PPI of the nickel foam matrix and 400 is the mesh size of the aluminum powder), and discharge begins. The catalyst is the self-made catalyst mentioned above.

[0143] Example 20. Unlike Example 19, the aluminum powder was loaded onto a 10 PPI nickel foam matrix, assembled into an aqueous aluminum-air battery (denoted as 10 / 400, where 10 represents the PPI of the nickel foam matrix and 400 is the mesh size of the aluminum powder), and discharge was initiated.

[0144] Example Twenty-one. Unlike Example Nineteen, the aluminum powder was loaded into a 20 PPI nickel foam matrix, and assembled into an aqueous aluminum-air battery (denoted as 20 / 400, where 20 represents the PPI of the nickel foam matrix and 400 is the mesh size of the aluminum powder), and discharged.

[0145] Example Twenty-two. Unlike Example Nineteen, the aluminum powder was loaded into a 75 PPI nickel foam matrix, and assembled into an aqueous aluminum-air battery (denoted as 75 / 400, where 75 represents the PPI of the nickel foam matrix and 400 is the mesh size of the aluminum powder), and discharged.

[0146] Example Twenty-three. Unlike Example Nineteen, the aluminum powder was loaded into a 110 PPI nickel foam matrix, and assembled into an aqueous aluminum-air battery (denoted as 110 / 400, where 110 represents the PPI of the nickel foam matrix and 400 is the mesh size of the aluminum powder), and discharged.

[0147] As shown in Table 2, the aluminum powder battery capacity of Example Fourteen was 54.6 mAh; the aluminum powder battery capacity of Example Fifteen was 17.7 mAh; and the aluminum powder battery capacity of Example Sixteen was 43 mAh. The aluminum powder battery capacity of Example Seventeen was 40.4 mAh; and the aluminum powder battery capacity of Example Eighteen was 39 mAh. It can be observed that as the PPI of the nickel foam decreased from 110 to 30, the pore size of the nickel foam matrix increased, and the capacity of the aluminum powder increased. As the PPI of the nickel foam decreased from 30 to 10, the pore size of the nickel foam matrix continued to increase, and the capacity of the aluminum powder decreased. The discharge capacity of the batteries formed with the 30 PPI, 20 PPI, and 75 PPI nickel foam matrices were greater than the discharge capacity of the batteries formed with the 10 PPI and 110 PPI nickel foam matrices. Figure 17 As shown in Table 3, the aluminum powder battery capacity of Example Nineteen was 36.9 mAh; the aluminum powder battery capacity of Example Twenty was 10.8 mAh; and the aluminum powder battery capacity of Example Twenty-one was 35.8 mAh / g. The aluminum powder battery capacity of Example Twenty-two was 28.5 mAh; and the aluminum powder battery capacity of Example Twenty-three was 9.8 mAh. It can be observed that as the PPI of the nickel foam decreased from 110 to 20, the pore size of the nickel foam matrix increased, and the capacity of the aluminum powder increased. As the PPI of the nickel foam decreased from 20 to 10, the pore size of the nickel foam matrix continued to increase, and the capacity of the aluminum powder decreased. The discharge capacity of the batteries formed with the 30 PPI, 20 PPI, and 75 PPI nickel foam matrices were greater than the discharge capacity of the batteries formed with the 10 PPI and 110 PPI nickel foam matrices.

[0148] Figure 18 The basic aluminum-air battery reaction is as follows: In a basic condition, the aluminum anode reaction process is:

[0149] The basic aluminum-air battery reaction is as follows: In a basic condition, the aluminum anode reaction process is:

[0150] ​

[0151] The formation reaction of the aluminum anode passivation layer under alkaline conditions:

[0152]

[0153] (6) is the dissolution reaction of aluminum anode under alkaline conditions, and (7) and (8) are the passivation layer formation reactions.

[0154] Under alkaline conditions, a conjugate corrosion reaction occurs on the aluminum anode:

[0155]

[0156] 4H2O+3e - →4OH - +2H2↑(9).

[0157] Under alkaline conditions, the positive electrode reaction process is as follows:

[0158]

[0159] During the discharge process of an aluminum-air battery, as shown in reactions (6) to (8) at the negative electrode, the aluminum negative electrode loses electrons and becomes Al(OH)4. - Al(OH)4 - Upon reaching saturation in the electrolyte, aluminum decomposes into Al2O3, which is the dissolution and passivation process of aluminum. This dissolution and passivation process is an important part of the normal operation of aluminum-air batteries in an alkaline environment. Oxygen at the positive electrode receives electrons lost by aluminum from the external circuit and is reduced to hydroxide ions. The dissolution and passivation behavior of the aluminum negative electrode plays an important role in the performance of aluminum-air batteries. Rapidly dissolving aluminum negative electrodes can enable the battery to provide a large current; however, the high passivation rate of aluminum negative electrodes also greatly shortens the battery life. While maintaining the activity of aluminum negative electrodes, moderately suppressing the passivation rate of aluminum negative electrodes can improve the discharge performance of the battery. Therefore, it is necessary to promote reaction (6) and suppress reaction (7) and reaction (8).

[0160] Reaction (9) is a hydrogen evolution corrosion reaction, and reactions (6), (8), and (9) form a conjugate corrosion reaction. Electrons formed on the aluminum surface in reaction (6) and active water molecules formed on the aluminum surface in reaction (8) can react in reaction (9) and release hydrogen gas. Of course, isolated water molecules in the electrolyte can also react in reaction (9) on the aluminum surface. Reaction (9) consumes electrons obtained in reaction (6), reducing the energy conversion efficiency of the battery. Inhibiting reaction (9) can improve the discharge performance of the battery.

[0161] The factors affecting reaction (6) are: the activity of Al and the concentration of hydroxide ions c[OH] -The smaller the particle size of the aluminum powder, the higher the activity of Al, and the reaction (6) can be promoted. The smaller the pore size of the nickel foam substrate, the higher the concentration of hydroxyl, and the reaction (6) can be promoted. Conversely, the larger the particle size of the aluminum powder, the lower the activity of Al, and the reaction (6) can be inhibited. The larger the pore size of the nickel foam substrate, the lower the concentration of hydroxyl, and the reaction (6) can be inhibited.

[0162] The influencing factors of the reactions (7) and (8) are the concentration c[Al(OH)4 - ] of Al(OH)4 - . The larger the pore size of the nickel foam substrate, the faster the mass transfer of Al(OH)4 - , the lower the c[Al(OH)4 - ], and the passive layer is less likely to be generated, and thus the reactions (7) and (8) can be inhibited. The larger the particle size of the aluminum powder, the lower the c[Al(OH)4 - ], and the passive layer is less likely to be generated, and thus the reactions (7) and (8) can be inhibited. Conversely, the smaller the pore size of the nickel foam substrate, the slower the mass transfer of Al(OH)4 - , the higher the c[Al(OH)4 - ], and the passive layer is more likely to be generated, and thus the reactions (7) and (8) can be promoted. The smaller the particle size of the aluminum powder, the higher the c[Al(OH)4 - ], and the passive layer is more likely to be generated, and thus the reactions (7) and (8) can be promoted.

[0163] The reaction (9) is related to the reactions (6) and (8). The electrons on the surface of the aluminum negative electrode obtained in the reaction (6) and the active water molecules on the surface of the aluminum negative electrode obtained in the reaction (8) are likely to react (9) to obtain hydrogen. Therefore, the reactions (6) and (8) can be inhibited to inhibit the reaction (9).

[0164] In order to improve the discharge performance of the battery, the reaction (6) needs to be promoted and the reactions (7) to (9) need to be inhibited. The particle size of the aluminum powder has opposite effects on the reactions (6) and (7) to (9), and the pore size of the nickel foam substrate has opposite effects on the reactions (6) and (7) to (9). Therefore, when the particle size of the aluminum powder is within a suitable range and the pore size of the nickel foam substrate is within a suitable range, the reaction (6) can be promoted and the reactions (7) to (9) can be inhibited.

[0165] As Figure 19As shown, when the particle size of the aluminum powder is within the appropriate particle size range and the pore size of the nickel foam matrix is within the appropriate pore size range, and the small-pore-size nickel foam is matched with the small-particle-size aluminum powder, the main performance is to promote reaction (6). When the particle size of the aluminum powder is within the appropriate particle size range and the pore size of the nickel foam matrix is within the appropriate pore size range, and the large-pore-size nickel foam is matched with the large-particle-size aluminum powder, the main performance is to inhibit reactions (7)-(9). When the particle size of the aluminum powder is within the appropriate particle size range and the pore size of the nickel foam matrix is within the appropriate pore size range, and the small-pore-size nickel foam is matched with the large-particle-size aluminum powder, the performance is to promote reaction (6) and inhibit reactions (7)-(9). When the particle size of the aluminum powder is within the appropriate particle size range and the pore size of the nickel foam matrix is within the appropriate pore size range, and the large-pore-size nickel foam is matched with the small-particle-size aluminum powder, the performance is to promote reaction (6) and inhibit reactions (7)-(9).

[0166] Specifically, first, when the OH - concentration near the aluminum powder negative electrode is increased or the particle size of the aluminum powder is reduced, Al is more likely to react with OH - to generate Al(OH)4 - . At the same time, the increase of Al(OH)4 - directly leads to the increase of Al(OH)3 and Al2O3, that is, the increase of the OH - concentration near the aluminum powder negative electrode and the reduction of the particle size of the aluminum powder not only improve the reactivity of aluminum, but also accelerate the passivation of the aluminum powder. Second, the Al(OH)3 and Al2O3 passivation films generated after the dissolution of aluminum prevent the further oxidation of the aluminum powder to some extent, and have the effect of inhibiting the dissolution of aluminum. However, Al2O3 is unstable under high OH - concentration, and Al is easily dissolved in the electrolyte, causing the Al(OH)3 and Al2O3 passivation films to fall off from the surface of the aluminum powder, exposing active Al, thereby further accelerating the passivation of the aluminum powder. In the process of falling off, the Al(OH)3 and Al2O3 passivation films will carry a part of the unreacted aluminum powder into the electrolyte, reducing the utilization rate of the aluminum powder, leading to unstable battery discharge voltage, fluctuations, and reduced battery discharge capacity. The passivation film also hinders the contact between the aluminum powder and the electrolyte and the contact between the aluminum powders, resulting in inhibition of the electrochemical activity of the aluminum powder.

[0167] Secondly, the standard reduction potential of aluminum / aluminum oxide (-2.35 V vs. SHE) is lower than the potential of hydrogen evolution reaction (-0.83 V vs. SHE), therefore, aluminum is thermodynamically unstable in water or aqueous solution. The oxidation of aluminum and the reduction of hydrogen ions in the electrolyte near the aluminum constitute a micro-battery. As the conjugate reaction process, i.e. reaction (6), reaction (8), reaction (9) shows, the dissolution of aluminum generates electrons, Al(OH)3dehydrates, water is hydrogen-evolved at the cathode, forming a conjugate corrosion reaction. When the ionized hydrogen ions in the electrolyte solution get enough electrons released by the oxidation of aluminum, they will combine to generate H2, and this reaction usually occurs on the surface of the aluminum negative electrode. The general steps of the cathodic reduction reaction of H2O molecules on the aluminum surface are as follows: H2O molecules are hydrogen-evolved on the cathode and migrate to the aluminum surface, H2O molecules obtain electrons on the aluminum surface to generate H atoms adsorbed on the aluminum surface, H atoms recombine on the aluminum surface to generate H2molecules, and H2molecules desorb to form H2gas bubbles.

[0168] Since H2is continuously evolved from the electrolyte solution to the air after its generation, the activity of the product of reaction (9) in the electrolyte solution is low. From the perspective of kinetics, more Al and OH - react to generate more electrons, and a large number of electrons combine with H2O on the surface of the aluminum to generate more H2. The evolved hydrogen gas also insulates the aluminum powder and the electrolyte, increases the transfer impedance of Al(OH)4 - and OH - , and reduces the battery capacity and voltage.

[0169] Thirdly, the pore size of the foamed nickel is large and the particle size of the aluminum powder is small, which is not conducive to the fixation of the aluminum powder by the foamed nickel, and part of the aluminum powder may fall off from the pore size of the foamed nickel matrix into the electrolyte, i.e. when the pore size of the foamed nickel matrix increases to a certain extent, the number of the three-dimensional skeletons of the foamed nickel matrix decreases, which will lead to the weakening of the confinement of the aluminum powder by the foamed nickel matrix, thereby reducing the discharge capacity and utilization rate of the aluminum powder.

[0170] Example Twenty-Four. Different from Example Fourteen, the aluminum powder is replaced by magnesium powder, and a water-based magnesium-air battery is assembled and started to discharge.

[0171] Example Twenty-Five. Different from Example Fourteen, the aluminum powder is replaced by iron powder, and a water-based iron-air battery is assembled and started to discharge.

[0172] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A metal powder negative electrode for aqueous metal-air batteries, characterized in that, The application relates to a metal powder negative electrode for an aqueous metal-air battery, which comprises: a foamed nickel base with a porous structure formed inside; metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder and aluminum powder; the foamed nickel base can be poured with new metal powder after the reaction of the metal powder; a leakage-proof layer arranged on the foamed nickel base and used for preventing the metal powder from leaking out; wherein when the metal powder is zinc powder, the PPI of the foamed nickel base is 10-30; when the metal powder is aluminum powder, the PPI of the foamed nickel base is 20-75; the diameter of the metal powder is 0.018mm-0.18mm; and the leakage-proof layer is a waterproof and air-permeable film. The application relates to a metal powder negative electrode for an aqueous metal-air battery, which comprises: a foamed nickel base with a porous structure formed inside; metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder and aluminum powder; the foamed nickel base can be poured with new metal powder after the reaction of the metal powder; a leakage-proof layer arranged on the foamed nickel base and used for preventing the metal powder from leaking out; wherein when the metal powder is zinc powder, the PPI of the foamed nickel base is 10-30; when the metal powder is aluminum powder, the PPI of the foamed nickel base is 20-75; the diameter of the metal powder is 0.018mm-0.18mm; and the leakage-proof layer is a waterproof and air-permeable film. The application relates to a metal powder negative electrode for an aqueous metal-air battery, which comprises: a foamed nickel base with a porous structure formed inside; metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder and aluminum powder; the foamed nickel base can be poured with new metal powder after the reaction of the metal powder; a leakage-proof layer arranged on the foamed nickel base and used for preventing the metal powder from leaking out; wherein when the metal powder is zinc powder, the PPI of the foamed nickel base is 10-30; when the metal powder is aluminum powder, the PPI of the foamed nickel base is 20-75; the diameter of the metal powder is 0.018mm-0.18mm; and the leakage-proof layer is a waterproof and air-permeable film. The application relates to a metal powder negative electrode for an aqueous metal-air battery, which comprises: a foamed nickel base with a porous structure formed inside; metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder and aluminum powder; the foamed nickel base can be poured with new metal powder after the reaction of the metal powder; a leakage-proof layer arranged on the foamed nickel base and used for preventing the metal powder from leaking out; wherein when the metal powder is zinc powder, the PPI of the foamed nickel base is 10-30; when the metal powder is aluminum powder, the PPI of the foamed nickel base is 20-75; the diameter of the metal powder is 0.018mm-0.18mm; and the leakage-proof layer is a waterproof and air-permeable film. The application relates to a metal powder negative electrode for an aqueous metal-air battery, which comprises: a foamed nickel base with a porous structure formed inside; metal powder filled in the porous structure; the metal powder is selected from at least one of zinc powder and aluminum powder; the foamed nickel base can be poured with new metal powder after the reaction of the metal powder; a leakage-proof layer arranged on the foamed nickel base and used for preventing the metal powder from leaking out; wherein when the metal powder is zinc powder, the PPI of the foamed nickel base is 10-30; when the metal powder is aluminum powder, the PPI of the foamed nickel base is 20-75; the diameter of the metal powder is 0.018mm-0.18mm; and the leakage-proof layer is a waterproof and air-permeable film. ​ 2. The metal powder negative electrode for a water- based metal-air battery according to claim 1, characterized by, ​ 3. A water- based metal-air battery, characterized by, ​ ​ ​ ​ ​ ​ 4. The aqueous metal-air cell according to claim 3, wherein ​ ​ wherein the concentration of soluble acetate is 0.04 mol L -1 ~ 0.3 mol L -1 ; The concentration of the strong base is 1 mol L -1 ~ 6 mol L -1 .

5. The aqueous metal-air cell according to claim 3, wherein ​ ​ ​ 6. The aqueous metal-air cell according to claim 5, wherein ​ 7. The aqueous metal-air cell according to claim 5, wherein ​ 8. A method for producing the aqueous metal-air battery as claimed in any one of claims 3 to 7, characterized by, ​ ​ ​ ​ 9. The production method of a water-based metal-air battery according to claim 8, characterized by, ​ ​ ​ ​ 10. The production method of a water-based metal-air battery according to claim 8, characterized by, ​ ​ ​ ​

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