Positive electrode material and preparation method thereof, positive plate and battery

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a positive electrode material, a preparation method thereof, a positive plate and a battery. The positive electrode material comprises nickel hydroxide, wherein the structural formula of the nickel hydroxide is Ni (1-a-b) ZnaXb (OH) 2; wherein a is greater than 0 and less than or equal to 0.1, b is greater than or equal to 0 and less than or equal to 0.05, X is a metal element in the water-soluble metal salt, and X is selected from one or more of Ca, Y, Mg, Ti and Yb and does not comprise Al. The nickel hydroxide is doped with zinc, crystal form distortion in the charging and discharging process is reduced, active substance pulverization is inhibited, and the electrode structure is more stable; in addition, the zinc doping can optimize the electron transfer path of Ni < 2 + > / Ni < 3 + >, reduce the charge transfer resistance, ensure that the conductivity and the charging efficiency of the battery are not affected while reducing the cost, and prolong the service life of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and in particular relates to a positive electrode material and its preparation method, a positive electrode sheet, and a battery. Background Technology

[0002] Ni(OH)₂ boasts advantages such as high power density, safety, and environmental friendliness, making it widely used in nickel-metal hydride (Ni / Cd), Ni / Fe, Ni / MH, and Ni / Zn battery systems. Traditional nickel hydroxide electrodes often improve conductivity and charging efficiency through cobalt doping, coating, or external addition. However, the extremely uneven distribution of cobalt resources makes the development of high-performance, safe, and cobalt-free nickel electrodes crucial for enhancing the market competitiveness of Ni / Cd, Ni / Fe, Ni / MH, and Ni / Zn battery systems and promoting their stable and sustainable development. Summary of the Invention

[0003] The technical problem to be solved by this invention is: to address the cost issues caused by the use of cobalt in current nickel electrodes, and to promote the stable and sustainable development of battery systems such as Ni / Cd, Ni / Fe, Ni / MH, and Ni / Zn, making them more competitive in the market, this invention provides a cathode material, its preparation method, a cathode sheet, and a battery.

[0004] To address the aforementioned technical problems, in one aspect, embodiments of the present invention provide a positive electrode material, comprising nickel hydroxide, wherein the nickel hydroxide has the structural formula Ni. (1-a-b) Zn a X b (OH)2; Where 0 < a ≤ 0.1, 0 ≤ b ≤ 0.05, X is a metal element in a water-soluble metal salt, and X is selected from one or more of Ca, Y, Mg, Ti, and Yb, and X does not include Al.

[0005] In one embodiment, the nickel hydroxide is spherical with a diameter of 5-50 μm and a specific surface area of ​​50-150 m². 2 / g.

[0006] In one embodiment, the positive electrode material further includes a positive electrode binder, a positive electrode conductive agent, and additives; The amount of the positive electrode binder added is 0.01-3% of the mass of nickel hydroxide; The amount of the positive electrode conductive agent added is 1-20% of the mass of nickel hydroxide; The amount of the additive added is 0.1-5% of the mass of nickel hydroxide.

[0007] In one embodiment, the positive electrode binder is a neutral nonionic fluorine-free binder.

[0008] In one embodiment, the positive electrode binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, hydroxypropyl starch, styrene, hydroxyethylcellulose, hydroxypropyl methylcellulose, chitosan, polyacrylonitrile, styrene-butadiene rubber, polyacrylic acid, and polyacrylate; and / or, The positive electrode conductive agent is selected from one or more of conductive metal powders and conductive carbon materials; and / or The additive is selected from one or more of titanium dioxide, yttrium oxide, ytterbium oxide, erbium oxide, calcium hydroxide, thulium oxide, and lutetium oxide.

[0009] On the other hand, embodiments of the present invention provide a method for preparing a cathode material, used to prepare a cathode material as described in any of the preceding claims, the preparation method comprising the following steps: The metal salts of Ni / Zn / X are dissolved in deionized water to obtain mixed solution A; Prepare a mixed solution B of sodium hydroxide solution and ammonia solution; Slowly add mixed solution B to the mixed solution A while stirring continuously, adjust the pH value, and obtain a precipitate after standing. The precipitate is filtered, and the washed precipitate is placed in an oven to dry. Calcination of the precipitate, followed by grinding or ball milling after natural cooling to room temperature, yields a product with the structural formula Ni. (1-a-b) Zn a X b Nickel hydroxide (OH)2.

[0010] In one embodiment, the concentration of the mixed solution A is 1-5 mol / L; The concentration of sodium hydroxide solution in the mixed solution B is 0.5-3 mol / L, and the concentration of ammonia solution is 0.2-1 mol / L.

[0011] In one embodiment, the drying temperature of the precipitate is 60-100°C, and the drying time is 8-24 hours; The calcination temperature of the precipitate is 200-500℃, and the calcination time is 3-5 hours.

[0012] On the other hand, embodiments of the present invention provide a positive electrode sheet, including a positive electrode current collector and a positive electrode material layer, wherein the positive electrode material layer is disposed on at least one surface of the positive electrode current collector; the positive electrode material layer includes the positive electrode material as described in any of the preceding claims or a positive electrode material prepared by the method for preparing the positive electrode material as described in any of the preceding claims.

[0013] In another aspect, embodiments of the present invention provide a battery including a negative electrode, a separator, an electrolyte, and a positive electrode as described above, wherein the separator is disposed between the positive electrode and the negative electrode.

[0014] The cathode material provided in this invention, when zinc is doped into the nickel hydroxide structure, allows zinc to partially replace some of the nickel positions in the Ni(OH)₂ lattice, forming a stable solid solution structure. Zinc ions play a supporting and stabilizing role in the crystal structure, suppressing excessive expansion and contraction of the lattice during the conversion process. Even during charge and discharge, despite volume strain, zinc ions help maintain the integrity of the crystal structure, reducing lattice distortion and thus effectively suppressing crystal form distortion. Simultaneously, the stable crystal structure prevents the active material particles from easily breaking down and pulverizing, ensuring the overall stability of the electrode structure and improving its cycle stability and lifespan.

[0015] Additionally, due to Zn 2+ Its electronic configuration is 3d 10 (Fully filled d orbitals) can affect the electronic environment of Ni(OH)₂. When zinc is doped into the nickel hydroxide structure, the introduction of zinc may enhance the covalent nature of the Ni-O bond, making Ni… 2+ More prone to losing electrons (reducing Ni) 2+ →Ni 3+ Furthermore, it can optimize the band structure, potentially introducing defect energy levels and promoting electron hopping, thereby optimizing Ni. 2+ / Ni 3+ The electron transfer path allows electrons to move more quickly and smoothly in Ni. 2+ and Ni 3+ This facilitates charge transfer between cells, reduces charge transfer resistance, and improves the overall conductivity of the battery.

[0016] The cathode material in this embodiment does not contain cobalt. Zn doping ensures the integrity of the cobalt-free nickel hydroxide cathode structure during cycling, reduces crystal distortion during charging and discharging, and lowers charge transfer resistance, ensuring that the battery's conductivity and charging efficiency are not affected, thus improving battery life. Detailed Implementation

[0017] To make the technical problems solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0018] Currently, the price of cobalt, a raw material in the production of nickel hydroxide, indirectly affects the production cost of nickel-metal hydride batteries. Therefore, replacing cobalt with other materials in the production of nickel hydroxide cathode material is crucial for cost control. However, reducing the cobalt content in the battery affects its conductivity and charging efficiency. Therefore, how to reduce battery costs without compromising conductivity and charging efficiency is a pressing issue that the industry needs to address.

[0019] To address the aforementioned issues, this application provides a cathode material that can reduce battery costs without affecting battery conductivity and charging efficiency.

[0020] This invention provides a positive electrode material, including nickel hydroxide, wherein the nickel hydroxide has the structural formula Ni. (1-a-b) Zn a X b (OH)2; where 0 < a ≤ 0.1, 0 ≤ b ≤ 0.05, X is a metal element in a water-soluble metal salt, X is selected from one or more of Ca, Y, Mg, Ti, Yb, and X does not include Al.

[0021] The nickel hydroxide in this application is doped with zinc. During the charging and discharging process of a nickel-metal hydride battery, the nickel hydroxide in the cathode material undergoes a reversible redox reaction, interconverting between nickel hydroxide (Ni(OH)2) and nickel hydroxyl oxide (NiOOH). This conversion process is accompanied by a volumetric strain of approximately 15%. This repeated volume change generates enormous stress on the crystal structure of the material. When the stress exceeds the material's tolerance limit, it leads to crystal distortion. After long-term cycling, the originally stable crystal structure is destroyed, resulting in the pulverization and shedding of the active material.

[0022] When zinc is doped into the nickel hydroxide structure, it can partially replace some of the nickel positions in the Ni(OH)₂ lattice, forming a stable solid solution structure. Zinc ions act as a "support" and "stabilizer" in the crystal structure, suppressing excessive expansion and contraction of the lattice during transformation. During charge and discharge, even with volumetric strain, zinc ions help maintain the integrity of the crystal structure, reducing lattice distortion and thus effectively suppressing crystal form distortion. Simultaneously, the stable crystal structure prevents the active material particles from breaking down and pulverizing, ensuring the overall stability of the electrode structure and improving its cycle stability and lifespan.

[0023] Additionally, due to Zn 2+ Its electronic configuration is 3d 10 (Fully filled d orbitals) can affect the electronic environment of Ni(OH)₂. When zinc is doped into the nickel hydroxide structure, the introduction of zinc may enhance the covalent nature of the Ni-O bond, making Ni… 2+More prone to losing electrons (reducing Ni) 2+ →Ni 3+ Furthermore, it can optimize the band structure, potentially introducing defect energy levels and promoting electron hopping, thereby optimizing Ni. 2+ / Ni 3+ The electron transfer path allows electrons to move more quickly and smoothly in Ni. 2+ and Ni 3+ This facilitates charge transfer between cells, reduces charge transfer resistance, and improves the overall conductivity of the battery.

[0024] The cathode material in this embodiment does not contain cobalt. Zn doping ensures the integrity of the cobalt-free nickel hydroxide cathode structure during cycling, reduces crystal distortion during charging and discharging, and lowers charge transfer resistance, ensuring that the battery's conductivity and charging efficiency are not affected, thus improving battery life.

[0025] Furthermore, the nickel hydroxide in this application does not contain Al. Excessive Al doping will affect the spherical structure, causing the structure to change from spherical to ellipsoidal, or even to an irregular shape, thereby affecting the porosity and the content of active material per unit volume.

[0026] In one embodiment, the nickel hydroxide is spherical with a diameter of 5-50 μm and a specific surface area of ​​50-150 m². 2 / g. Within the above range, it is possible to ensure the densest packing of spherical nickel hydroxide, reduce electrode porosity, and increase the content of active material per unit volume.

[0027] Irregularly structured particles, due to their chaotic shapes (such as flakes, blocks, and angular shapes), create numerous voids when stacked, resulting in low actual filling volume per unit volume. In contrast, the symmetrical structure of the spherical particles in this embodiment allows them to be densely packed like stacked spheres (i.e., "dense packing"), significantly reducing ineffective voids within the electrode, decreasing porosity, and increasing the content of active material per unit volume. Furthermore, the regular shape of the nickel hydroxide particles avoids the uneven electrolyte distribution problem caused by "localized over-density" in irregular structures, thus improving rate performance.

[0028] For batteries, active materials are the core components involved in electrochemical reactions; the higher the content of active materials per unit volume, the higher the energy density of the battery. Spherical nickel hydroxide has a diameter of 5-50 μm and a specific surface area of ​​50-150 m². 2 Within the range of / g, spherical nickel hydroxide can achieve the densest packing, improving the energy density of nickel-metal hydride batteries. However, if the diameter is too large (exceeding 50 μm) and / or the specific surface area is too large (exceeding 150 m²), the energy density is reduced. 2 / g) may result in particles that are too loose, thus reducing the bulk density; while a diameter that is too small (less than 5μm) and / or a specific surface area that is too small (less than 50m²) may lead to particles that are too loose, thus reducing the bulk density;2 When the density is / g), it will cause the reaction to be too dense, resulting in insufficient reaction and limiting energy output.

[0029] In addition, the symmetrical structure of the spherical particles can buffer the volume changes during the charging and discharging process (about 15% volume strain is accompanied by the interconversion of nickel hydroxide (Ni(OH)2) and nickel hydroxy oxide (NiOOH)), reduce particle breakage, maintain the integrity of the electrode structure, and thus significantly extend the cycle life of the battery.

[0030] Therefore, in this embodiment, spherical nickel hydroxide can comprehensively improve the energy density, rate performance, and cycle life of nickel-metal hydride batteries.

[0031] In one embodiment, the positive electrode material further includes a positive electrode binder, a positive electrode conductive agent, and additives.

[0032] In the preparation of the positive electrode sheet, spherical nickel hydroxide, positive electrode binder, positive electrode conductive agent, and additives are mixed to obtain a slurry. Coating this slurry onto the positive electrode current collector yields the positive electrode sheet. The positive electrode binder firmly adheres the spherical nickel hydroxide and positive electrode conductive agent to the positive electrode current collector, reducing the shedding of active material due to volume expansion / contraction during charging and discharging, and stabilizing the structural and volume changes of the positive electrode active material during charging and discharging.

[0033] The positive electrode binder and the positive electrode conductive agent work synergistically to build a conductive network, effectively promoting electron conduction inside the electrode and reducing the battery's internal resistance.

[0034] Additives are generally optimized for specific performance. The additives in this application are intended to further stabilize the β-NiOOH phase, reduce the formation of the γ phase, and suppress electrode expansion, thereby improving battery capacity, cycle life, charge and other performance characteristics.

[0035] The amount of positive electrode binder added is 0.01-3% of the mass of nickel hydroxide. Specifically, taking the mass of nickel hydroxide as 100, the amount of positive electrode binder added can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3% of the mass of nickel hydroxide or any range of the above values.

[0036] The amount of the positive electrode conductive agent added is 1-20% of the mass of nickel hydroxide. Specifically, taking the mass of nickel hydroxide as 100, the amount of the positive electrode conductive agent added can be 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% of the mass of nickel hydroxide, or any range of the above values.

[0037] The amount of additive added is 0.1-5% of the mass of nickel hydroxide. Specifically, taking the mass of nickel hydroxide as 100, the amount of additive added can be 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.4%, 2.8%, 3%, 3.5%, 3.8%, 4%, 4.3%, 4.8%, 5% or any range of the above values ​​of nickel hydroxide.

[0038] In one embodiment, the positive electrode binder is a neutral nonionic fluorine-free binder. A neutral nonionic fluorine-free binder is a binder that simultaneously meets the requirements of neutral environmental suitability, nonionic properties, and fluorine-free composition. Neutral means that the positive electrode binder is pH inert in the application system (such as battery electrolyte), maintaining stability in acidic, neutral, and alkaline environments; nonionic properties mean that its molecular structure does not contain ionizable ionic groups (such as anionic groups like carboxyl groups and sulfonic acid groups, or cationic groups like ammonium groups), achieving bonding only through intermolecular forces (such as van der Waals forces and hydrogen bonds); fluorine-free means that the positive electrode binder does not contain fluorine. Through the use of a fluorine-free binder and cobalt-free nickel hydroxide, the positive electrode material is fluorine-free and cobalt-free.

[0039] The advantages of neutral nonionic fluorine-free adhesives are: 1) By uniformly coating the active material (nickel hydroxide) and the positive electrode conductive agent through hydrogen bonds / van der Waals forces, the active material and the positive electrode conductive agent are tightly bound together, which improves the peel strength, reduces the possibility of electrode cracking after cycling, and maintains the integrity of the electrode structure. This allows the battery to maintain good electrochemical performance after multiple cycles, thereby improving the battery cycle life.

[0040] 2) Because neutral nonionic fluorine-free adhesives do not contain -COO - Groups such as -SO3H can prevent reaction with OH groups. - A chemical reaction occurs. This allows the positive electrode binder to maintain stable chemical properties in an alkaline battery environment, preventing it from reacting with OH groups. - The reaction that causes the positive electrode binder to degrade or fail is beneficial for the long-term stable operation of the battery. Furthermore, the positive electrode binder does not contain carboxylic acid groups, so it is not easy to chelate with metal ions, thus avoiding affecting the stability of the electrode interface and causing battery capacity loss.

[0041] 3) Non-ionic positive electrode binders do not carry any charge and will not electrostatically repel negatively charged substances (such as carbon black). During the preparation of positive electrode slurry, the positive electrode binder can more easily mix with nickel hydroxide and positive electrode conductive agent to form a well-dispersed slurry, reducing the agglomeration or sedimentation of positive electrode slurry caused by charge interaction.

[0042] 4) Fluorinated organic compounds are non-degradable, and their extensive use will have irreversible effects on human health and the environment. The positive electrode binder of this application does not contain fluorine, which can reduce the environmental hazards caused by fluorine (such as fluoride emission pollution) and is in line with the concept of green and sustainable development.

[0043] In one embodiment, the positive electrode binder is selected from one or more of polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), methyl cellulose (MC), hydroxypropyl starch (HPS), eutectic adhesive, hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC), chitosan, polyacrylonitrile (PAN), styrene-butadiene rubber (SBR), polyacrylic acid, and polyacrylate.

[0044] In one embodiment, the positive electrode conductive agent is selected from one or more of conductive metal powder and conductive carbon materials.

[0045] In one embodiment, the conductive metal powder includes one or more of nickel powder and tin powder. The conductive carbon material includes one or more of conductive carbon black, graphite, carbon nanotubes, graphene, and carbon fiber.

[0046] In one embodiment, the additive is selected from one or more of titanium dioxide (TiO2), yttrium oxide (Y2O3), ytterbium oxide (Yb2O3), erbium oxide (Er2O3), calcium hydroxide (Ca(OH)2), thulium oxide (Tm2O3), and lutetium oxide (Lu2O3).

[0047] On the other hand, embodiments of the present invention provide a method for preparing a cathode material, used to prepare the cathode material described in any of the above embodiments, the preparation method comprising the following steps: S1. Dissolve Ni metal salt, Zn metal salt and X metal salt in deionized water to obtain mixed solution A; S2. Prepare a mixed solution B of sodium hydroxide solution and ammonia water; S3. Slowly add mixed solution B dropwise to the mixed solution A while stirring continuously, adjust the pH value, and obtain a precipitate after standing.

[0048] S4. Filter the precipitate and put the washed precipitate into an oven to dry it; S5. Calcine the precipitate, and after naturally cooling to room temperature, grind or ball-mill it to obtain the product with the structural formula Ni. (1-a-b) Zn a X b Nickel hydroxide with a spherical structure of (OH)2.

[0049] In one embodiment, in step S1, the Ni metal salt, Zn metal salt, and X metal salt in the mixed solution A are dissolved in deionized water at a certain molar ratio, resulting in a concentration of 1-5 mol / L for the mixed solution A. The Ni metal salt includes, but is not limited to, Ni nitrates, chlorides, and sulfates. The Zn metal salt includes, but is not limited to, Zn nitrates, chlorides, and sulfates. The X metal salt includes, but is not limited to, X metal nitrates, chlorides, and sulfates.

[0050] By dissolving Ni metal salt, Zn metal salt and X metal salt in deionized water according to the above molar ratio, a mixed solution A of 1-5 mol / L can be prepared.

[0051] In one embodiment, the concentration of sodium hydroxide solution in the mixed solution B is 0.5-3 mol / L, and the concentration of ammonia solution is 0.2-1 mol / L. Using deionized water, a sodium hydroxide solution with a concentration of 0.5-3 mol / L and an ammonia solution with a concentration of 0.2-1 mol / L can be prepared. After mixing, a sodium hydroxide-ammonia solution is formed, which is a composite system with both strong alkalinity and complexing ability. Adding mixed solution B dropwise to mixed solution A with continuous stirring can achieve simultaneous precipitation and uniform doping of Ni / Zn / X ions, ultimately obtaining a uniformly doped solid solution.

[0052] In one embodiment, in step S3, the reaction conditions between mixed solution A and mixed solution B are: pH 8-11, reaction time 8-12 h, and reaction temperature 50-80 °C. After the reaction is complete, the mixture is allowed to stand for 8-24 h to ensure that the precipitate is fully settled.

[0053] In one embodiment, in step S4, the drying temperature of the precipitate is 60-100°C, and the drying time is 8-24 hours. After settling, the precipitate is filtered and repeatedly washed with deionized water until the washing solution is neutral to remove any possible impurity ions. After washing, it is placed in an oven for drying at 60-100°C for 8-24 hours.

[0054] In step S5, the calcination conditions are as follows: the calcination temperature of the precipitate is 200-500℃, and the calcination time is 3-5 hours. After drying, the dried powder is placed in a muffle furnace for calcination at 200-500℃ for 3-5 hours. During calcination, the high temperature provides thermal activation, which promotes crystal growth and the solid solution of element X in nickel hydroxide. After calcination, the powder is naturally cooled to room temperature, and then the product is subjected to appropriate grinding or ball milling to obtain cobalt-free and fluorine-free Ni. (1-a-b) Zn a X b (OH)2 cathode material.

[0055] In another aspect, embodiments of the present invention provide a positive electrode sheet, including a positive current collector and a positive electrode material layer, wherein the positive electrode material layer is disposed on at least one surface of the positive current collector; the positive electrode material layer includes the positive electrode material of any of the above embodiments or the positive electrode material prepared by the preparation method of the positive electrode material of any of the above embodiments.

[0056] The cathode material includes nickel hydroxide, which is doped with zinc. This reduces crystal distortion during charging and discharging, inhibits pulverization of the active material, and makes the cathode sheet more stable, preventing the cathode material layer from pulverizing and detaching. Furthermore, zinc doping optimizes Ni… 2+ / Ni 3+ The electron transfer path is optimized, reducing charge transfer resistance. Nickel hydroxide has a spherical structure, which allows for the densest packing and improves the energy density of nickel-metal hydride batteries.

[0057] In one embodiment, the positive current collector is a nickel foam matrix with an areal density of 230-430 g / m³. 2 A slurry is obtained by mixing spherical nickel hydroxide, positive electrode binder, positive electrode conductive agent and additives. The positive electrode sheet can be obtained by coating the slurry onto a nickel foam substrate.

[0058] In one embodiment, the positive electrode sheet is prepared by two methods.

[0059] Method 1: 1) Prepare deionized water, add one or more additives to the deionized water, and mechanically stir for 5-10 minutes. The amount of deionized water added is 25-30% of the mass of spherical nickel hydroxide, and the amount of additives added is 0.1-5% of the mass of spherical nickel hydroxide; 2) Add one or more positive electrode conductive agents, and stir for 5-20 minutes. The amount of positive electrode conductive agents added is 1-20% of the mass of spherical nickel hydroxide; 3) Add cobalt-free spherical nickel hydroxide, and stir for 30-120 minutes; 4) Add one or more positive electrode binders, and stir for 3-8 minutes. The amount of positive electrode binders added is 0.01-3% of the mass of spherical nickel hydroxide.

[0060] The mechanical stirring speed is 200-800 rpm. After the slurry is prepared, it is evenly coated onto a surface with a density of 230-430 g / m³. 2 On the nickel foam substrate, after rolling and drying, it is cut into positive electrode sheets of appropriate size.

[0061] Method 2: 1) Weigh a certain mass of spherical nickel hydroxide powder; 2) Add one or more additives and mechanically stir for 10-30 minutes. The amount of additives added is 0.1-5% of the mass of the spherical nickel hydroxide; 3) Add one or more positive electrode conductive agents and stir for 5-20 minutes. The amount of positive electrode conductive agents added is 1-20% of the mass of the spherical nickel hydroxide; 4) Add one or more positive electrode binders and stir for 5-20 minutes. The amount of positive electrode binders added is 0.01-3% of the mass of the spherical nickel hydroxide.

[0062] After the slurry is prepared, it is evenly coated onto surfaces with a surface density of 230-430 g / m². 2 On the nickel foam substrate, after rolling and drying, it is cut into positive electrode sheets of appropriate size.

[0063] It should be noted that the order in which the positive electrode binder, positive electrode conductive agent and additives are added in the above preparation method is only an example and should not be regarded as a limitation of the present invention.

[0064] In another aspect, embodiments of the present invention provide a battery, including a negative electrode, a separator, an electrolyte, and a positive electrode as described in the above embodiments, wherein the separator is disposed between the positive electrode and the negative electrode.

[0065] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is disposed on at least one surface of the negative electrode current collector, which is based on a perforated nickel-plated steel strip substrate.

[0066] The negative electrode active material layer includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent. The negative electrode active material layer is obtained by blending the negative electrode active material, the negative electrode binder, and the negative electrode conductive agent. The preparation of the negative electrode sheet is existing technology and will not be described in detail here.

[0067] The negative electrode active material includes one or more of the following: iron-based materials such as Fe2O3 / Fe3O4, zinc-based materials such as Zn / ZnO, cadmium-based materials such as Cd / CrO, and cobalt-free hydrogen storage alloys.

[0068] In one embodiment, the diaphragm is a conventional diaphragm, which may be a ceramic diaphragm, a porous polymer diaphragm (such as polyethylene, polypropylene), a non-woven fabric diaphragm, an inorganic-organic composite diaphragm, a fiber diaphragm (such as cellulose, glass fiber), a composite diaphragm, 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 diaphragms.

[0069] In one embodiment, the electrolyte comprises one or more of NaOH, KOH, and LiOH.

[0070] By assembling the above-mentioned positive electrode, negative electrode and separator, injecting electrolyte and sealing, different types of cobalt-free and fluorine-free nickel-iron, nickel-zinc, nickel-cadmium and nickel-metal hydride batteries can be prepared.

[0071] The present invention will be further illustrated by the following examples.

[0072] Example 1 This embodiment illustrates the cathode material and its preparation method disclosed in this invention, including the following steps: Preparation of Ni 0.9 Zn 0.05 Ca 0.05 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.9:0.05:0.05 to prepare a 3.2 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 1.6 mol / L sodium hydroxide solution and a 0.5 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material one.

[0073] Example 2 Preparation of Ni 0.94 Zn 0.05 Ca 0.01 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.94:0.05:0.01 to prepare a 3 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 3 mol / L sodium hydroxide solution and a 1 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material II.

[0074] Example 3 Preparation of Ni 0.95 Zn0.05 (OH)2 1) Dissolve Ni / Zn / Ti metal salts in deionized water at a molar ratio of 0.95:0.05 to prepare a 3.5 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 3 mol / L sodium hydroxide solution and a 0.2 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while stirring continuously, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material three.

[0075] Example 4 Preparation of Ni 0.93 Zn 0.03 Ti 0.04 (OH)2 1) Dissolve Ni / Zn / Ti metal salts in deionized water at a molar ratio of 0.93:0.03:0.04 to prepare a 1.5 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material four.

[0076] Example 5 Preparation of Ni 0.87 Zn 0.1 Y 0.03 (OH)2 1) Dissolve Ni / Zn / Y metal salts in deionized water at a molar ratio of 0.87:0.1:0.03 to prepare a 2 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material five.

[0077] Example 6 Preparation of Ni 0.87 Zn 0.08 Ti 0.05 (OH)2 1) Dissolve Ni / Zn / Ti metal salts in deionized water at a molar ratio of 0.87:0.08:0.05 to prepare a 2.5 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material six.

[0078] Example 7 Preparation of Ni 0.93 Zn 0.02 Ti 0.05 (OH)2 1) Dissolve Ni / Zn / Ti metal salts in deionized water at a molar ratio of 0.93:0.02:0.05 to prepare a 3 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material seven.

[0079] Comparative Example 1 Preparation of Ni 0.95 Ca 0.05 (OH)2 1) Dissolve Ni / Ca metal salts in deionized water at a molar ratio of 0.95:0.05 to prepare a 3.5 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 3.2 mol / L sodium hydroxide solution and a 0.2 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while stirring continuously, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material VIII.

[0080] Comparative Example 2 Preparation of Ni 0.75 Zn 0.2 Ca 0.05 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.75:0.2:0.05 to prepare a 3.2 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 1.6 mol / L sodium hydroxide solution and a 1.2 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material nine.

[0081] Comparative Example 3 Preparation of Ni 0.87 Zn 0.05 Ca 0.08 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.87:0.05:0.08 to prepare a 4 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 3.2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain the cathode material X.

[0082] Comparative Example 4 Preparation of Ni 0.77 Zn 0.15 Ca 0.08 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.77:0.15:0.08 to prepare a 3.2 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 3.2 mol / L sodium hydroxide solution and a 0.6 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75°C; 4) Allow the mixture to stand for 24 hours after the reaction is complete; 5) Filter the precipitate and wash it repeatedly with deionized water until the washings are neutral; 6) Place the washed precipitate in an oven and dry it at 85°C for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450°C for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material eleven.

[0083] Comparative Example 5 Preparation of Ni(OH)2 1) Dissolve Ni metal salt in deionized water to prepare a 3.2 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 1.6 mol / L sodium hydroxide solution and a 1.2 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while stirring continuously, adjust the pH to 9, react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, let it stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material XII.

[0084] Comparative Example 6 Preparation of Ni 0.9 Zn 0.05 Ca 0.05 (OH)2 1) Dissolve Ni / Zn / Ca metal salts in deionized water at a molar ratio of 0.9:0.05:0.05 to prepare a 0.6 mol / L mixed solution A; 2) Prepare a mixed solution B using deionized water, consisting of a 0.5 mol / L sodium hydroxide solution and a 0.2 mol / L ammonia solution; 3) Slowly add mixed solution B dropwise to mixed solution A while continuously stirring, adjust the pH to 9, and react for 10 hours at a temperature of 75℃; 4) After the reaction is complete, allow the mixture to stand for 24 hours; 5) Filter the precipitate and wash it repeatedly with deionized water until the washing solution is neutral; 6) Place the washed precipitate in an oven and dry it at 85℃ for 20 hours; 7) Place the dried powder in a muffle furnace and calcine it at 450℃ for 4 hours; 8) After calcination, allow it to cool naturally to room temperature, and then grind or ball-mill the product appropriately to obtain cathode material thirteen.

[0085] Experimental Procedure and Results SEM tests were performed on the cathode materials of Examples 1-7 and Comparative Examples 1-6, and the test results are shown in Table 1.

[0086] Table 1 Example 8 This embodiment illustrates the battery and its preparation method disclosed in this invention, and includes the following steps: Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0087] Preparation of negative electrode: 1) Add 2.5g carboxymethyl cellulose, 5g sodium polyacrylate, and 5g hydroxypropyl cellulose to 200g water, and stir with a mechanical mixer at 400rpm for 5-10 minutes; 2) Add 500g La 0.86 Ce 0.11 Y 0.02 Ni 4.70 Mn 0.36 Al 0.33 Zr 0.023) Add 5g of styrene-butadiene rubber and continue stirring for 5-10 minutes; 4) Coat the slurry evenly onto the perforated nickel-plated steel strip substrate and dry; 5) Cut the electrode sheet into a negative electrode sheet with a length of 71 mm and a width of 39 mm.

[0088] Electrolyte: Add 15.9g KOH, 13.4g NaOH and 1.7g LiOH to 500g water, and dissolve to obtain an electrolyte with a specific gravity of 1.28g / mL and a concentration of 7.86-8.10mol / L.

[0089] Separator: Polyolefin fiber separator with a thickness of 0.12.

[0090] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0091] Example 9 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of cathode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0092] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0093] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0094] Example 10 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of cathode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0095] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0096] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0097] Example 11 Preparation of positive electrode: 1) Weigh 500g of positive electrode material one; 2) Add 5g of Y2O3 and 10g of Yb2O3 and stir for 20min; 3) Add 20g of graphite and stir for 20min; 4) Add 10g of styrene-butadiene rubber and stir for 5min; 5) Coat the slurry evenly with a surface density of 280g / m². 2 6) The foamed nickel substrate is rolled and dried; 7) The electrode is cut into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0098] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0099] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0100] Example 12 Preparation of positive electrode: 1) Weigh 500g of positive electrode material 3; 2) Add 5g of Y2O3 and 10g of Yb2O3 and stir for 20min; 3) Add 20g of graphite and stir for 20min; 4) Add 10g of styrene-butadiene rubber and stir for 5min; 5) Coat the slurry evenly with a surface density of 280g / m². 2 6) The foamed nickel substrate is rolled and dried; 7) The electrode is cut into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0101] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0102] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0103] Comparative Example 7 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g polytetrafluoroethylene and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0104] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0105] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0106] Comparative Example 8 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0107] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0108] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0109] Comparative Example 9 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g sodium carboxymethyl cellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0110] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0111] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0112] Comparative Example 10 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0113] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0114] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0115] Comparative Example 11 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of cathode material (dodecyl) and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0116] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0117] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0118] Comparative Example 12 Preparation of positive electrode: 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g sodium carboxymethylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g of positive electrode material and continue stirring for 60 minutes; 5) Add 10g styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m³. 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0119] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0120] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0121] Comparative Example 13 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g Ni 0.9 Co 0.05 Ca 0.05 (OH)2 continued stirring for 60 minutes; 5) Add 10g of styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m². 2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0122] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0123] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0124] Comparative Example 14 1) Add 5g Ca(OH)2, 5g Y2O3, and 10g Yb2O3 to 150g deionized water and stir with a mechanical mixer for 5 minutes; 2) Add 2g methylcellulose and 2g hydroxypropyl methylcellulose; 3) Add 20g graphite and stir for 20 minutes; 4) Add 500g Ni 0.85 Al 0.1 Ca 0.05 (OH)2 continued stirring for 60 minutes; 5) Add 10g of styrene-butadiene rubber and continue stirring for 5 minutes; 6) Coat the slurry evenly with a surface density of 280g / m².2 7) Dry the foamed nickel substrate; 8) Cut the electrode sheet into a positive electrode sheet with a length of 50 mm and a width of 39 mm.

[0125] The preparation of the negative electrode, the formulation of the electrolyte, and the use of the diaphragm are the same as in Example 8.

[0126] By winding the above-mentioned positive electrode, negative electrode, and separator, and then injecting liquid and sealing, a nickel-metal hydride battery with a capacity of 750mAh of type AAA can be assembled.

[0127] Experimental Procedure and Results Test 1: The nickel-metal hydride batteries of Examples 8-12 and Comparative Examples 7-14 were subjected to formation treatment as follows.

[0128] Formation methods: (1) Charge at 150mA for 100min, then discharge at 150mA to 1.0V; (2) Charge at 75mA for 200min, then discharge at 150mA to 1.0V; (3) Charge at 150mA for 300min, then discharge at 150mA to 1.0V.

[0129] After formation, the nickel-metal hydride batteries of Examples 8-12 and Comparative Examples 7-14 were subjected to three IEC capacity tests. The internal resistance and active material utilization rate are shown in Table 2, where the active material utilization rate = (third IEC capacity / ball nickel content) / 289 * 100%; Table 2 Table 2 shows that the nickel-metal hydride batteries prepared using cobalt-free and fluorine-free cathode materials in Examples 8-12 have a resistance below 25 mΩ and an active material utilization rate above 90% after formation. A comparison of Examples 8-12 with Comparative Example 7 shows that the resistance and active material utilization rate of the batteries are not significantly different when using fluorine-containing binders versus fluorine-free binders. A comparison of Examples 8-12 with Comparative Example 13 shows that the resistance and active material utilization rate of the batteries are not significantly different when using Co-doped cathode materials versus Zn-doped cathode materials.

[0130] By comparing Examples 8-12 with Comparative Examples 8 and 14, it can be seen that Comparative Example 8 uses a non-spherical cobalt-free and fluorine-free cathode material. In Comparative Example 14, due to Al doping, the spherical structure transforms into an ellipsoidal or even irregular shape. The non-spherical structure cannot achieve the densest packing, which affects the content of active material per unit volume. At the same time, it cannot buffer the volume change during the charging and discharging process, resulting in slightly lower resistance and active material utilization.

[0131] By comparing Examples 8-12 with Comparative Example 9, it can be seen that Comparative Example 9 uses an ionic binder. Due to the interaction of charges, the ionic binder is prone to slurry agglomeration or sedimentation, which affects the performance of the battery. Its resistance and utilization rate of active materials are slightly worse.

[0132] A comparison of Examples 8-12 with Comparative Examples 10-11 shows that Comparative Examples 10-11 used undoped spherical cobalt-free and fluorine-free cathode materials, which could not suppress crystal distortion or reduce charge transfer resistance, and its resistance and utilization rate of active materials were slightly worse.

[0133] By comparing Comparative Examples 10-11 with Comparative Example 12, it can be seen that Comparative Example 12 uses a spherical cobalt-free and fluorine-free cathode material without Zn doping and an ionic binder, resulting in poorer resistance and utilization of active materials.

[0134] Test 2: The nickel-metal hydride batteries of Examples 8-12 and Comparative Examples 7-14 were subjected to cycle tests according to the following method.

[0135] Cyclic testing method: Charge at 750mA for 72 minutes, let stand for 30 minutes, then discharge at 750mA to 1V; repeat the above charge-discharge test until the battery capacity decays to 60% of the first discharge capacity. Record the battery capacity after each cycle test.

[0136] The results of the charge-discharge cycle test are shown in Table 3: Table 3 Table 3 shows that the cobalt-free and fluorine-free nickel-metal hydride batteries prepared using cobalt-free and fluorine-free cathode materials in Examples 8-12 exhibit good cycle performance, achieving nearly 300 cycles at 1C. A comparison of Examples 8-12 with Comparative Example 7 shows that the cycle performance of the batteries using fluorine-containing binders and fluorine-free binders is not significantly different. A comparison of Examples 8-12 with Comparative Example 13 shows that the cycle performance of the batteries using Co-doped cathode materials and Zn-doped cathode materials is not significantly different.

[0137] By comparing Examples 8-12 with Comparative Examples 8 and 14, it can be seen that Comparative Example 8 uses a non-spherical cobalt-free and fluorine-free cathode material. In Comparative Example 14, due to Al doping, the spherical structure transforms into an ellipsoidal or even irregular shape. The non-spherical structure cannot achieve the densest packing, which affects the content of active material per unit volume. At the same time, it cannot buffer the volume change during the charging and discharging process, resulting in slightly poorer cycle performance of the battery.

[0138] By comparing Examples 8-12 with Comparative Example 9, it can be seen that Comparative Example 9 uses an ionic binder. Due to the interaction of charges, the ionic binder is prone to causing the slurry to agglomerate or settle, which affects the performance of the battery and its cycle performance is slightly worse.

[0139] A comparison of Examples 8-12 with Comparative Examples 10-11 shows that Comparative Examples 10-11 used undoped spherical cobalt-free and fluorine-free cathode materials, which could not suppress crystal distortion, could not reduce charge transfer resistance, and affected its cycle performance.

[0140] By comparing Examples 8-12 with Comparative Example 12, it can be seen that Comparative Example 12 uses an undoped spherical cobalt-free and fluorine-free cathode material and an ionic binder, resulting in poorer cycle performance.

[0141] Test 3: The nickel-metal hydride batteries of Examples 8-12 and Comparative Examples 7-14 were subjected to charge tests according to the following method.

[0142] Charge test method: (1) Charge at 75mA for 16 hours and rest for 30 minutes; (2) Discharge at 75mA to 1.0V and record the capacity C0; (3) Rest at a specified temperature (room temperature, 45℃ or 60℃) for 28 days; (4) Charge at 75mA for 16 hours and rest for 30 minutes; (5) Discharge at 75mA to 1.0V and record the capacity C1. Where charge = C1 / C0*100%.

[0143] The results of the charge test are shown in Table 4: Table 4 The results in Table 4 show that the nickel-metal hydride batteries prepared using cobalt-free and fluorine-free cathode materials in Examples 8-12 have good charge performance. They retain more than 80% charge after 28 days of storage at room temperature, more than 75% charge after 28 days of storage at 45 degrees Celsius, and more than 65% charge after 28 days of storage at 60 degrees Celsius.

[0144] A comparison of Examples 8-12 with Comparative Example 7 shows that the battery charge performance is not significantly different when using fluorine-containing binders and fluorine-free binders. A comparison of Examples 8-12 with Comparative Example 13 shows that the battery charge performance is not significantly different when using Co-doped cathode materials and Zn-doped cathode materials.

[0145] The charge properties of the batteries in Comparative Examples 8-12 and 14 were degraded to varying degrees.

[0146] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A positive electrode material, characterized in that, Includes nickel hydroxide, wherein the structural formula of nickel hydroxide is Ni (1-a-b) Zn a X b (OH)2; Where 0 < a ≤ 0.1, 0 ≤ b ≤ 0.05, X is a metal element in a water-soluble metal salt, and X is selected from one or more of Ca, Y, Mg, Ti, and Yb, and X does not include Al.

2. The cathode material as described in claim 1, characterized in that, The nickel hydroxide is spherical with a diameter of 5-50 μm and a specific surface area of ​​50-150 m² / g.

3. The positive electrode material as described in claim 1, characterized in that, The positive electrode material also includes a positive electrode binder, a positive electrode conductive agent, and additives; The amount of the positive electrode binder added is 0.01-3% of the mass of nickel hydroxide; The amount of the positive electrode conductive agent added is 1-20% of the mass of nickel hydroxide; The amount of the additive added is 0.1-5% of the mass of nickel hydroxide.

4. The cathode material as described in claim 3, characterized in that, The positive electrode binder is a neutral nonionic fluorine-free binder.

5. The cathode material as described in claim 3, characterized in that, The positive electrode binder is selected from one or more of polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, methylcellulose, hydroxypropyl starch, methylcellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, chitosan, polyacrylonitrile, styrene-butadiene rubber, and polyacrylate; and / or, The positive electrode conductive agent is selected from one or more of conductive metal powders and conductive carbon materials; and / or The additive is selected from one or more of titanium dioxide, yttrium oxide, ytterbium oxide, erbium oxide, calcium hydroxide, thulium oxide, and lutetium oxide.

6. A method for preparing a positive electrode material, characterized in that, The preparation method for obtaining the cathode material according to any one of claims 1-5 includes the following steps: The metal salts of Ni / Zn / X are dissolved in deionized water to obtain mixed solution A; Prepare a mixed solution B of sodium hydroxide solution and ammonia solution; Slowly add mixed solution B to the mixed solution A while stirring continuously, adjust the pH value, and obtain a precipitate after standing. The precipitate is filtered, and the washed precipitate is placed in an oven to dry. Calcination of the precipitate, followed by grinding or ball milling after natural cooling to room temperature, yields a product with the structural formula Ni. (1-a-b) Zn a X b Nickel hydroxide (OH)2.

7. The method for preparing the cathode material as described in claim 6, characterized in that, The concentration of the mixed solution A is 1-5 mol / L; The concentration of sodium hydroxide solution in the mixed solution B is 0.5-3 mol / L, and the concentration of ammonia solution is 0.2-1 mol / L.

8. The method for preparing the cathode material as described in claim 6, characterized in that, The precipitate is dried at a temperature of 60-100℃ for 8-24 hours. The calcination temperature of the precipitate is 200-500℃, and the calcination time is 3-5 hours.

9. A positive electrode plate, characterized in that, It includes a positive current collector and a positive electrode material layer, wherein the positive electrode material layer is disposed on at least one surface of the positive current collector; the positive electrode material layer includes the positive electrode material according to any one of claims 1-5 or the positive electrode material prepared by the method for preparing the positive electrode material according to any one of claims 6-8.

10. A battery, characterized in that, It includes a negative electrode, a separator, an electrolyte, and a positive electrode as described in claim 9, wherein the separator is disposed between the positive electrode and the negative electrode.

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