Zinc negative electrode material, zinc negative electrode, negative electrode preparation method and nickel-zinc battery

Abstract

The invention provides a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method and a nickel-zinc battery in order to solve the problem that in the prior art, zinc dendrites are likely to be generated in the charging and discharging process of the zinc negative electrode, and battery short circuit is caused. The zinc negative electrode material comprises a negative electrode active material and a negative electrode additive, the negative electrode additive comprises a first negative electrode additive, and the first negative electrode additive is zinc coated with an aluminum-containing substance; the aluminum-containing substance comprises one or more of alloy aluminum, aluminate, an aluminum compound and an aluminum organic matter, and the negative electrode active material comprises zinc oxide. According to the zinc negative electrode material provided by the invention, the first negative electrode additive in the negative electrode additives comprises the zinc coated with the aluminum-containing substance, a protective film layer is formed on the surface of the zinc after the zinc is coated with the aluminum-containing substance, and the protective film layer has remarkable advantages in multiple aspects of inhibiting zinc corrosion and dendritic crystal growth, improving stability and improving electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode and battery manufacturing, and particularly relates to a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery. Background Art

[0002] Nickel-zinc batteries have gradually been widely used in the fields of consumer electronics, energy storage, and electric vehicles due to their advantages of high energy density, environmental friendliness, and non-toxicity. However, the structural stability and cycle life of the zinc negative electrode in nickel-zinc batteries are still important issues restricting their widespread use. Zinc dendrites are easily generated on the zinc negative electrode during charge and discharge, leading to battery short circuits; in addition, the electrode will also fail due to corrosion and volume expansion, thereby shortening the battery life. These problems urgently need to be solved through material modification to improve the stability and safety of nickel-zinc batteries. Summary of the Invention

[0003] Aiming at the problem that zinc dendrites are easily generated on the zinc negative electrode during charge and discharge, resulting in battery short circuits in the prior art, a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery are provided.

[0004] The technical solutions adopted by the present invention to solve the above technical problems are as follows: On the one hand, the present invention provides a zinc negative electrode material, including a negative electrode active material and a negative electrode additive, the negative electrode additive includes a first negative electrode additive, and the first negative electrode additive is zinc coated with an aluminum-containing substance; The aluminum-containing substance includes one or more of alloy aluminum, aluminate, aluminum chloride, aluminum oxide, and aluminum organic matter, and the negative electrode active material includes zinc oxide.

[0005] Optionally, the alloy aluminum includes one or more of aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, and aluminum-zinc alloy; and / or, the aluminate includes one or more of calcium aluminate, zinc aluminate, beryllium aluminate, silicon aluminate, and aluminum phosphate; and / or, the aluminum chloride includes one or more of aluminum monochloride, aluminum dichloride, and aluminum trichloride; and / or, the aluminum oxide includes one or more of α-aluminum oxide, γ-aluminum oxide, and aluminum tetroxide; and / or, the aluminum organic matter includes one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0006] Optionally, in the first negative electrode additive, the mass content of the aluminum-containing substance is 2%-5%.

[0007] Optionally, in the zinc coated with the aluminum-containing substance, the mass ratio of the aluminum-containing substance to zinc is 1:1-5.

[0008] Optionally, in the zinc coated with the aluminum-containing substance, the coating thickness of the aluminum-containing substance is 2-10 μm.

[0009] Optionally, the negative electrode additive further includes a second negative electrode additive, and the second negative electrode additive includes In2O3 and Bi2O3; In the zinc negative electrode material, the added mass of In2O3 is 0.5%-1.5%, and the added mass of Bi2O3 is 2%-8%.

[0010] Optionally, the preparation method of the first negative electrode additive includes at least one of chemical deposition method, in-situ deposition method, and spray drying method.

[0011] Optionally, the negative electrode active material includes one or more of zinc and zinc oxide.

[0012] On the other hand, the present invention provides a zinc negative electrode, which includes a negative electrode current collector and a negative electrode material layer. The negative electrode material layer is disposed on the negative electrode current collector, and the negative electrode material layer includes the above-mentioned zinc negative electrode material.

[0013] Optionally, the negative electrode material layer further includes a conductive agent, a thickening agent, and a binder; The mass ratio of the negative electrode active material, the negative electrode additive, the conductive agent, the thickening agent, and the binder is 86-90:6-8:0.5-2:1-4:0.1-1; and / or, the conductive agent includes one or more of nickel powder, nickel carbonyl powder, cobalt oxide, graphene, graphite, acetylene black, and carbon powder; and / or, the thickening agent includes one or more of sodium polyacrylate, sodium carboxymethyl cellulose, and polyvinyl alcohol; and / or, the binder includes one or more of styrene-butadiene rubber and polytetrafluoroethylene.

[0014] Optionally, the preparation method of the zinc negative electrode includes the following operations: Take the conductive agent and the thickening agent, mix them evenly, then add the second negative electrode additive and mix evenly to obtain mixture A; Add the first negative electrode additive to mixture A, after blending, add the negative electrode active material and mix evenly again to obtain mixture B; Add the binder to mixture B and mix evenly to obtain the negative electrode slurry; Coat the negative electrode slurry onto the corresponding negative electrode current collector to obtain the zinc negative electrode.

[0015] On the other hand, the present invention provides a nickel-zinc battery, which includes a positive electrode, a separator, an electrolyte, and the above-mentioned zinc negative electrode or the zinc negative electrode prepared by the above-mentioned zinc negative electrode preparation method.

[0016] The beneficial effects of the present invention are as follows: The zinc negative electrode material provided by the present invention includes a negative electrode additive, and the first negative electrode additive in the negative electrode additive includes zinc coated with an aluminum-containing substance. The zinc coated with the aluminum-containing substance can form a dense protective film layer on the surface of the zinc, reduce the direct contact between the zinc and the electrolyte, and inhibit the corrosion of the zinc; at the same time, the Al in the aluminum-containing substance can react with the OH- ions in the alkaline electrolyte to generate aluminum compounds with a passivation effect, further slowing down the corrosion; on the one hand, the dense protective film layer formed on the zinc surface can improve the uniformity of the electrochemical reaction on the zinc surface, reduce the local current density, and thus inhibit the growth of dendrites. After the aluminum-containing substance is coated on the zinc , its dissolution and redeposition process is more uniform, reducing the rate of active material loss; on the other hand, the dense protective film layer formed helps zinc maintain the stability of the mechanical structure during long-term charging and discharging, reducing electrode deformation and volume expansion; the coating of the dense protective film layer can reduce the side reactions on the electrode surface, thereby reducing the polarization of the electrode and improving the discharge efficiency; in summary, zinc coated with aluminum-containing substances in zinc negative electrode materials has significant advantages in inhibiting zinc corrosion, dendrite growth, improving stability and improving electrochemical properties, providing new development ideas for improving the performance of nickel-zinc batteries and other related alkaline battery systems. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] The present invention provides a zinc negative electrode material, comprising a negative electrode active material and a negative electrode additive, wherein the negative electrode additive comprises a first negative electrode additive, and the first negative electrode additive comprises zinc coated with an aluminum-containing substance; The aluminum-containing substance includes one or more of alloy aluminum, aluminate, aluminum compound and aluminum organic matter, and the negative electrode active material includes zinc oxide.

[0019] It should be noted that the zinc negative electrode is extremely susceptible to corrosion in an alkaline electrolyte environment, resulting in frequent hydrogen escape and zinc dissolution, causing a sharp decrease in battery capacity and potential safety hazards; the zinc negative electrode material provided in the present application has a coating layer formed by an aluminum-containing substance that adheres to the zinc surface. With its dense characteristics, it blocks the direct interaction path between zinc and the electrolyte, thereby playing a role in inhibiting zinc corrosion. The aluminum element in the aluminum-containing substance has unique chemical activity, and reacts chemically with OH- ions in the alkaline electrolyte to generate aluminum compounds with significant passivation efficiency, further strengthening the corrosion resistance of the zinc surface.

[0020] During the charge and discharge process, zinc dendrites are likely to form on the zinc anode, which is also not conducive to improving the performance of nickel-zinc batteries. After the zinc is coated with an aluminum-containing coating layer, by optimizing the charge distribution, the peak value of the local current density is effectively reduced, the driving force for the rapid growth of dendrites is weakened, and the growth of dendrites is inhibited.

[0021] The aluminum-containing coating layer can effectively reduce the occurrence frequency of side reactions on the surface of the zinc electrode. By reducing the interfacial resistance between the electrode and the electrolyte, the polarization phenomenon of the electrode is significantly alleviated, and thus the power output efficiency of the battery during the discharge process is improved.

[0022] In some embodiments, the alloy aluminum includes one or more of aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, and aluminum-zinc alloy; the aluminate includes one or more of calcium aluminate, zinc aluminate, beryllium aluminate, silicon aluminate, and aluminum phosphate; and / or, the chloride of aluminum includes one or more of aluminum monochloride, aluminum dichloride, and aluminum trichloride; and / or, the oxide of aluminum includes one or more of α-aluminum oxide, γ-aluminum oxide, and aluminum tetroxide; and / or, the organic matter of aluminum includes one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

[0023] Specifically, the content of the aluminum-containing substance can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%.

[0024] In some embodiments, in the zinc coated with the aluminum-containing substance, the purity of zinc is 90%-95%, and the particle size is 20-80 μm.

[0025] In some embodiments, for the zinc coated with the aluminum-containing substance, the mass ratio of the aluminum-containing substance to zinc is 1:1-5.

[0026] Specifically, when the mass ratio of the aluminum-containing substance to zinc is limited within the above range, a protective film with a more appropriate quality can be formed on the surface of zinc. If the proportion of the aluminum-containing substance is too small, a complete, continuous, and dense protective film may not be formed, thus unable to effectively reduce the direct contact between zinc and the electrolyte, and the corrosion inhibition effect on zinc is weakened. If the proportion of the aluminum-containing substance is too large, the protective film may be too thick, affecting the electrochemical reaction activity of zinc and reducing the electrochemical performance of the battery; when the content of zinc is too high, the formed coating layer may not completely and evenly cover zinc, and thus cannot well inhibit zinc corrosion, affecting the overall performance of the battery.

[0027] In some embodiments, in the zinc coated with the aluminum-containing substance, the coating thickness of the aluminum-containing substance is 2-10 μm.

[0028] Specifically, when the coating thickness of the aluminum-containing substance is relatively thin, zinc ions can relatively easily diffuse through the coating film layer to the electrode surface for deposition; the coating film layer can provide some initial nucleation sites to guide the uniform deposition of zinc ions, prevent the rapid local aggregation of zinc ions to form dendrites, and the relatively thin coating film layer has a small hindrance to the diffusion of zinc ions, enabling the charge and discharge process of the battery to proceed relatively efficiently, and avoiding the difficulty of ion transport caused by an overly thick coating film layer from affecting the battery performance.

[0029] If the coating thickness is too thick, the diffusion of zinc ions through the coating film layer to the electrode surface will be greatly hindered, resulting in an increase in the internal resistance of the battery. Moreover, due to the difficulty of ion transport, a local ion concentration difference is formed inside the coating film layer or between the coating film layer and the electrode surface, which easily causes zinc dendrites to grow at the interface between the coating film layer and the electrode; During the battery assembly process or the charge and discharge cycle process, due to the volume change of the electrode material or external mechanical stress, the overly thick coating film layer is prone to cracking and falling off, which is not conducive to the protection of the zinc electrode.

[0030] In some embodiments, the negative electrode additive further includes a second negative electrode additive, and the second negative electrode additive includes In2O3 and Bi2O3; In the zinc negative electrode material, the added mass of In2O3 is 0.5% - 1.5%, and the added mass of Bi2O3 is 2% - 8%.

[0031] In2O3 plays roles such as improving conductivity and enhancing cycle stability in the battery negative electrode, thereby significantly improving the battery performance; specifically, when In2O3 is used as an additive in the zinc negative electrode material, it can effectively reduce the internal resistance of the battery, thereby improving the charge and discharge efficiency of the battery, and further significantly improving the overall conductivity of the electrode material. In addition, the structural stability of In2O3 enables it to maintain a relatively high capacity after multiple charge and discharge cycles. By compounding with other negative electrode materials such as graphite or silicon, In2O3 helps to alleviate the structural damage caused by volume changes during the charge and discharge process of these materials, thereby improving the cycle stability of the battery; Bi2O3 (bismuth oxide) plays roles such as improving the electrochemical performance, inhibiting dendrite formation, and enhancing the cycle life in the negative electrode material of nickel-zinc batteries; specifically, in nickel-zinc batteries, Bi2O3 as an additive can effectively inhibit the formation of dendrites, thereby improving the safety and cycle stability of the battery. By adding an appropriate amount of Bi2O3, a dendrite-free zinc anode can be prepared, which is beneficial to improving the energy density and power of the battery; Bi2O3 can alleviate the volume expansion problem during the charge and discharge process through compounding with zinc materials, and improve the cycle stability of the electrode material.

[0032] Specifically, the added mass of the In2O3 can be 0.5%, 1% or 1.5%; the added mass of the Bi2O3 can be 2%, 3%, 4%, 5%, 6%, 7% or 8%; In some embodiments, the preparation method of the first negative electrode additive includes at least one of chemical deposition method, in-situ deposition method and spray drying method.

[0033] Specifically, the chemical deposition method generates a dense aluminum-containing coating film on the zinc surface through chemical deposition; the zinc material is immersed in a solution containing aluminum, and aluminum-containing substances are deposited on the zinc surface through specific reaction conditions (such as controlling the pH value and reaction temperature).

[0034] The in-situ deposition method adjusts the composition of the electrolyte during the operation of the battery, so that aluminum-containing substances are gradually generated and deposited on the zinc surface during the electrode reaction.

[0035] The spray drying method sprays a suspension of aluminum-containing substances on the zinc surface, and then forms a uniform and dense aluminum-containing coating film through drying and solidification.

[0036] The aluminum-containing substances have good compatibility, adhesion and stability with the zinc surface, which helps to form a stable protective layer around the zinc particles, slows down the dissolution and corrosion reactions of zinc, and can self-repair during the charge and discharge process to adapt to the volume change of the electrode, thereby significantly extending the battery life and slowing down self-discharge.

[0037] In some embodiments, the negative electrode active material includes one or more of zinc and zinc oxide.

[0038] As an active metal, zinc is a key substance participating in the electrochemical reaction. During the discharge of the nickel-zinc battery, zinc turns into zinc ions and enters the electrolyte, and electrons form an electric current through the external circuit to realize the discharge function of the battery; zinc oxide can also participate in the reaction in the battery system. During the charging process, zinc oxide can be converted into zinc, increasing the total amount of active substances participating in the reaction inside the battery, which helps to improve the battery capacity and charge-discharge efficiency.

[0039] In another embodiment of the present invention, a zinc negative electrode is provided, which includes a negative electrode current collector and a negative electrode material layer. The negative electrode material layer is disposed on the negative electrode current collector, and the negative electrode material layer includes the above-mentioned zinc negative electrode material.

[0040] In some embodiments, the negative electrode material layer further includes a conductive agent, a thickening agent and a binder; The mass ratio of the negative electrode active material, the negative electrode additive, the conductive agent, the thickening agent and the binder is 86-90:6-8:0.5-2:1-4:0.1-1; and / or, the conductive agent includes one or more of nickel powder, nickel carbonyl powder, cobalt oxide, graphene, graphite, acetylene black and carbon powder; and / or, The thickener includes one or more of sodium polyacrylate, sodium carboxymethyl cellulose, and polyvinyl alcohol; and / or, The binder includes one or more of styrene-butadiene rubber and polytetrafluoroethylene.

[0041] Specifically, the conductive agent includes one or more of nickel powder, nickel carbonyl powder, cobalt oxide, graphene, graphite, acetylene black, and carbon powder; The thickener includes sodium polyacrylate (PAANa), sodium carboxymethyl cellulose (CMC), and polyvinyl alcohol (PVA), and the mass ratio of sodium polyacrylate:sodium carboxymethyl cellulose:polyvinyl alcohol is 1:7:2; The binder includes styrene-butadiene rubber (SBR) and polytetrafluoroethylene (PTFE), and the mass ratio of styrene-butadiene rubber (SBR):polytetrafluoroethylene (PTFE) is 3:7. In some embodiments, the preparation method of the zinc negative electrode includes the following operations: Take the conductive agent and the thickener, mix them evenly, then add the second negative electrode additive and mix evenly to obtain mixture A; Add the first negative electrode additive to mixture A, after blending, add the negative electrode active material and mix evenly again to obtain mixture B; Add the binder to mixture B and mix evenly to obtain the negative electrode slurry; Coat the negative electrode slurry onto the corresponding negative electrode current collector to obtain the zinc negative electrode.

[0042] Specifically, the specific preparation of the first negative electrode additive includes: Take an aluminum-containing substance and mix it with a solvent to form an aluminum-containing solution, then immerse zinc into the aluminum-containing solution, and deposit aluminum in the aluminum-containing solution onto the zinc surface by one of chemical deposition method, in-situ generation method, and spray drying method to obtain the first negative electrode additive, i.e., zinc coated with the aluminum-containing substance; Another embodiment of the present invention provides a nickel-zinc battery, including a positive electrode, a separator, an electrolyte, and the zinc negative electrode or the zinc negative electrode prepared by the preparation method of the zinc negative electrode.

[0043] Specifically, the separator is placed between the positive electrode and the negative electrode to form an electric core, and then the electric core is assembled with the battery case and filled with liquid to obtain the nickel-zinc battery; The nickel-zinc battery provided by the present invention has a zinc negative electrode. In the zinc negative electrode material, the zinc negative electrode material includes a negative electrode additive, and the first negative electrode additive in the negative electrode additive includes zinc coated with an aluminum-containing substance. The zinc coated with the aluminum-containing substance will form a dense protective film layer on the surface of the zinc, reducing the direct contact between the zinc and the electrolyte and inhibiting the corrosion of the zinc. At the same time, Al in the aluminum-containing substance can react with OH- ions in the alkaline electrolyte to generate an aluminum compound with a passivating effect, further slowing down the corrosion. On the one hand, the dense protective film layer formed on the surface of the zinc can improve the uniformity of the electrochemical reaction on the surface of the zinc, reduce the local current density, and thus inhibit the growth of dendrites. After the zinc is coated with the aluminum-containing substance, its dissolution and redeposition processes are more uniform, reducing the rate of loss of the active material. On the other hand, the formed dense protective film layer helps the zinc to maintain the stability of the mechanical structure during long-term charge and discharge processes, reducing electrode deformation and volume expansion. The coating of the dense protective film layer can reduce the side reactions on the surface of the zinc electrode, thereby reducing the polarization phenomenon of the electrode and improving the discharge efficiency. In summary, the zinc coated with the aluminum-containing substance in the zinc negative electrode material has significant advantages in inhibiting zinc corrosion, dendrite growth, enhancing stability, and improving electrochemical performance, providing new development ideas for improving the performance of nickel-zinc batteries and other related alkaline battery systems.

[0044] The positive electrode includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is selected from one or more of Ni(OH)2 (nickel hydroxide), ZnO, CoO (cobalt oxide), Ni powder, Ca(OH)2, Y2O3 (yttrium trioxide), and Yb2O3 (ytterbium trioxide); The positive electrode current collector is nickel foam with a basis weight of 280 g / m 2 of.

[0045] The positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent are blended to obtain the positive electrode active material layer.

[0046] The positive electrode conductive agent can be at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene, or reduced graphene oxide.

[0047] The separator can be an existing conventional separator, which can be a ceramic separator, a polymer separator, a non-woven fabric, an inorganic-organic composite separator, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP separators. The following further illustrates the present invention through examples.

[0048]

[0049] Example 1 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention, and includes the following operating steps: Preparing the negative electrode: Take calcium aluminate and mix it with a solvent to form a calcium aluminate solution, then immerse zinc into the calcium aluminate solution, and deposit calcium aluminate in the calcium aluminate solution on the zinc surface through chemical deposition to obtain zinc coated with an aluminum-containing substance (coating thickness is 5 μm), that is, the first negative electrode additive; In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:1; Mix 68% ZnO, 20% of the first negative electrode additive, 1% In2O3, 6% Bi2O3, 1.5% conductive agent, 3% binder, and 0.5% thickener to obtain a zinc negative electrode material slurry; Coat the zinc negative electrode material slurry on the surface of the negative electrode current collector, and obtain a zinc negative electrode through rolling, softening, and cutting.

[0050] Preparing the positive electrode: Mix Ni(OH)2, ZnO, CoO, Ni powder, Ca(OH)2, Y2O3, Yb2O3, graphite, CMC, and PTFE according to a mass ratio of 80:1:3:2:1:2:2:1:5:3 to obtain a positive electrode slurry; Coat the positive electrode slurry on the surface of the positive electrode current collector, and obtain a positive electrode of the nickel-zinc battery through rolling, softening, and cutting.

[0051] Preparing the electrolyte: Mix 30% KOH, 2% ZnO, 10% silica sol, 5% disodium hydrogen phosphate, and 53% water to obtain an electrolyte.

[0052] Stack the positive electrode, separator, and zinc negative electrode in sequence, with the separator in the middle of the positive and negative electrodes to prepare an electric core. Place the electric core in an outer packaging bag for drying, inject the above electrolyte, and obtain a nickel-zinc battery through processes such as vacuum packaging, standing, forming, and shaping.

[0053] Example 2 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention, and includes most of the operations in Example 1. The difference is that: Use aluminum-zinc alloy to coat zinc, and use the in-situ method for coating. The coating method is as follows: Disperse Zn evenly in ethanol, add an appropriate amount of dispersant polyvinylpyrrolidone to obtain a mixture; Then add aluminum-zinc alloy to the above mixture, and add reducing agent NaBH4 and stir to obtain a reactant; Use NH4OH to control the pH of the reactants and continue stirring for 2 hours for aging; Collect the reactants by centrifugation or filtration and wash the reactants with deionized water / ethanol; Dry at 80 - 100 °C and perform heat treatment at 300 - 500 °C to obtain zinc coated with aluminum-zinc alloy.

[0054] Example 3 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: Use alumina to coat zinc and use the spray drying method for coating. The operation method is as follows: Stir and mix alumina, polyvinylpyrrolidone dispersant, and ethanol in a mass ratio of 1:0.5:10 to obtain a mixture.

[0055] Feed the above mixture into a nozzle through a high-pressure pump and spray the mixture evenly on the surface of zinc by high-pressure spraying. After drying, obtain zinc coated with alumina.

[0056] Example 4 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: Use triethylaluminum to coat zinc.

[0057] Example 5 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:3.

[0058] Example 6 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:4.

[0059] Example 7 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a method for preparing a negative electrode, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:5.

[0060] Example 8 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:3.5.

[0061] Example 9 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the preparation of the zinc negative electrode, in the zinc coated with the aluminum-containing substance, the coating thickness of the aluminum-containing substance is 2 μm.

[0062] Example 10 This example is used to illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: In the zinc coated with the aluminum-containing substance, the coating thickness of the aluminum-containing substance is 10 μm.

[0063] Comparative Example 1 This comparative example is used to comparatively illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: The first negative electrode additive does not include zinc coated with an aluminum-containing substance.

[0064] Comparative Example 2 This comparative example is used to comparatively illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: The first negative electrode additive is zinc coated with graphite.

[0065] Comparative Example 3 This comparative example is used to comparatively illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: The first negative electrode additive is zinc coated with calcium oxide.

[0066] Comparative Example 4 This comparative example is used to comparatively illustrate a zinc negative electrode material, a zinc negative electrode, a negative electrode preparation method, and a nickel-zinc battery disclosed by the present invention. It includes most of the operations in Example 1, and the differences are as follows: The first negative electrode additive is calcium aluminate.

[0067] Performance Test The following performance tests were carried out on Examples 1-10 and Comparative Examples 1-4 prepared above: Cycle life At a temperature of 25 °C, charge the zinc-nickel batteries prepared in each example and comparative example at 1C to 1.9V and then charge at a constant voltage of 1.9V until the cut-off current is 13.5mA, discharge at 1C to 1.3V, repeat the charge and discharge until the battery capacity is reduced to 60% of the first charge, and record the number of charge and discharge cycles.

[0068] High-temperature cycle capacity retention rate (1) Under the condition of 25 °C, charge the battery to full charge in a constant current and constant voltage charging mode, charge at 0.2C to 1.9V, and then charge at a constant voltage of 1.9V until the cut-off current is 13.5mA to end the charging. (2) Place the fully charged battery in an oven at 60 °C and store it for 28 days. (3) After the storage is completed, discharge at 0.2C to 1.3V, then charge using the same charging method as in (1), let it stand for 10 min, and then discharge at 0.2C to 1.3V. Repeat the above charging and discharging steps 3 times.

[0069] Fill the obtained test results into Table 1.

[0070] Table 1 It can be seen from the test results in Table 1 that the cycle performance of Examples 1-10 is better than that of Comparative Examples 1-4, indicating that the zinc negative electrode material with aluminum-containing substance-coated zinc of the present invention can effectively improve the cycle life of nickel-zinc batteries, and plays a good role in inhibiting the growth of zinc dendrites and reducing corrosion, thereby maintaining the stability of the battery during multiple charge and discharge cycles; In terms of the high-temperature cycle capacity retention rate, the capacity retention rates of the examples are mostly between 40% and 50%, and the capacity recovery rates are between 88% and 95%. The capacity retention rate of Comparative Example 1 is 30%, and the capacity recovery rate is 85%. The capacity retention rate of Comparative Example 2 is 35%, and the capacity recovery rate is 88%. This shows that the zinc negative electrode material of the present invention can better maintain and recover the battery capacity in a high-temperature environment and reduce performance degradation; In Comparative Example 3, zinc coated with calcium oxide is used as the first negative electrode additive, and its test results are much worse than those of Example 1. The aluminum-containing substance-coated zinc can form a dense protective film, effectively blocking the contact between the electrolyte and zinc. Calcium oxide reacts with water to form calcium hydroxide. In the battery environment, this conversion may make the protective film structure loose and unable to tightly cover the zinc surface, resulting in easy penetration of the electrolyte, increasing the contact opportunity between zinc and the electrolyte, accelerating the corrosion of zinc, and affecting the service life of the battery. That is, it shows that the protective layer formed by calcium oxide-coated zinc has a worse effect than the protective layer formed by the aluminum-containing substance provided in this application; In Comparative Example 4, using calcium aluminate as the first negative electrode additive is also not conducive to improving the battery performance. The coating structure of aluminum-containing substances coating zinc improves the uniformity of the electrochemical reaction on the zinc surface, making the dissolution and redeposition processes of zinc more uniform, reducing the local current density. However, the pure aluminum-containing substances cannot directly act on the electrochemical reaction on the zinc surface and it is difficult to effectively inhibit dendrite growth; As can be seen from Examples 1-4, the cycling performance of Example 1 is slightly better than that of Examples 2-4. That is, calcium aluminate coating is relatively more excellent in improving the cycle life. It is speculated that the possible reason is related to the protective film characteristics formed by calcium aluminate on the zinc surface, making it better in inhibiting zinc corrosion and dendrite growth; From the test data of Example 1 and Examples 5-8, the test result of Example 1 is the best, followed by Examples 8 and 5, and there is no obvious difference between Examples 6-7. It is speculated that the reason is that in Example 1, the mass ratio of the aluminum-containing substance to zinc is 1:1, and the ratio of the aluminum-containing substance to zinc is relatively uniform, which is conducive to forming a uniform and complete protective layer on the zinc surface, reducing the direct contact between zinc and the electrolyte, and playing the role of inhibiting zinc corrosion. Compared with Example 1, in Examples 5-8, the content of zinc increases, and there may be a situation where the formed coating layer cannot completely and uniformly cover zinc, thus unable to effectively inhibit zinc corrosion and affecting the overall performance of the battery; Comparing Examples 9-10 with Example 1, the coating thickness of Example 1 is 5 μm, the coating thickness of Example 9 is 2 μm, and the coating thickness of Example 10 is 10 μm. The cycling performance and storage performance of Example 1 are better, indicating that when the coating thickness changes within a certain range, the battery performance fluctuates. Too thin or too thick coating layers may not be conducive to performance improvement. When the coating thickness in this application is limited to 5 μm, it can better balance the ion transport of the battery.

[0071] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A zinc negative electrode material, characterized in that, It includes a negative electrode active material and a negative electrode additive. The negative electrode additive includes a first negative electrode additive, and the first negative electrode additive is zinc coated with an aluminum-containing substance; The aluminum-containing substance includes one or more of alloy aluminum, aluminate, aluminum chloride, aluminum oxide, and aluminum organic compound. The negative electrode active material includes zinc oxide.

2. The zinc negative electrode material according to claim 1, wherein The alloy aluminum includes one or more of aluminum-copper alloy, aluminum-magnesium alloy, aluminum-manganese alloy, and aluminum-zinc alloy; and / or, the aluminate includes one or more of calcium aluminate, zinc aluminate, beryllium aluminate, silicon aluminate, and aluminum phosphate; and / or, the aluminum chloride includes one or more of aluminum monochloride, aluminum dichloride, and aluminum trichloride; and / or, the aluminum oxide includes one or more of α-aluminum oxide, γ-aluminum oxide, and aluminum tetroxide; and / or, the aluminum organic compound includes one or more of triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

3. The zinc negative electrode material according to claim 1, characterized in that, In the first negative electrode additive, the mass ratio of the aluminum-containing substance to zinc is 1:1 - 5.

4. A zinc negative electrode material according to claim 1, characterized in that, In the zinc coated with the aluminum-containing substance, the coating thickness of the aluminum-containing substance is 2 - 10 μm.

5. A zinc negative electrode material according to claim 1, characterized in that The negative electrode additive further includes a second negative electrode additive, and the second negative electrode additive includes In2O3 and Bi2O3; In the zinc negative electrode material, the added mass of In2O3 is 0.5% - 1.5%, and the added mass of Bi2O3 is 2% - 8%.

6. The zinc negative electrode material according to claim 1, characterized in that, The preparation method of the first negative electrode additive includes at least one of chemical deposition method, in-situ deposition method, and spray drying method.

7. A zinc negative electrode material according to claim 1, characterized in that, The negative electrode active material includes one or more of zinc and zinc oxide.

8. A zinc negative electrode, characterized in that, It includes a negative electrode current collector and a negative electrode material layer. The negative electrode material layer is disposed on the negative electrode current collector, and the negative electrode material layer includes the zinc negative electrode material according to any one of claims 1 - 7.

9. A zinc negative electrode according to claim 8, characterized in that, The negative electrode material layer further includes a conductive agent, a thickening agent, and a binder; The mass ratio of the negative electrode active material, the negative electrode additive, the conductive agent, the thickening agent, and the binder is 86 - 90:6 - 8:0.5 - 2:1 - 4:0.1 - 1; and / or The conductive agent includes one or more of nickel powder, nickel carbonyl powder, cobalt oxide, graphene, graphite, acetylene black, and carbon powder; and / or, The thickening agent includes one or more of sodium polyacrylate, sodium carboxymethyl cellulose, and polyvinyl alcohol; and / or, The binder includes one or more of styrene-butadiene rubber and polytetrafluoroethylene.

10. The preparation method of a zinc negative electrode according to claim 9, characterized in that, It includes the following operations: Take the conductive agent and the thickening agent, mix them evenly, then add the second negative electrode additive and mix evenly to obtain mixture A; Add the first negative electrode additive to mixture A, after co-mixing, add the negative electrode active material and mix evenly again to obtain mixture B; Add the binder to mixture B and mix evenly to obtain the negative electrode slurry; Coat the negative electrode slurry onto the corresponding negative electrode current collector to obtain the zinc negative electrode.

11. A nickel-zinc battery, characterized in that, It includes a positive electrode, a separator, an electrolyte, and the zinc negative electrode according to any one of claims 8 - 9 or the zinc negative electrode prepared by the preparation method of the zinc negative electrode according to claim 10.

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