Positive electrode material of nickel-metal hydride battery, preparation method of positive electrode material, nickel-metal hydride battery and electric equipment

Abstract

The invention provides a nickel-metal hydride battery positive electrode material and a preparation method thereof, a nickel-metal hydride battery and electric equipment, the nickel-metal hydride battery positive electrode material is nickel-containing hydroxide doped with cobalt element, and the ratio D (100) / D (001) of the grain size D (100) of the (100) crystal face of the nickel-metal hydride battery positive electrode material to the grain size D (001) of the (001) crystal face of the nickel-metal hydride battery positive electrode material is 1.50-2.20. According to the nickel-metal hydride battery positive electrode material provided by the embodiment of the invention, the cobalt element is doped in the positive electrode material, so that the oxygen evolution overpotential can be improved, the attenuation of the capacity and the service life of the positive electrode material at high temperature can be slowed down, the grain size ratio of the (100) crystal face to the (001) crystal face of the nickel-metal hydride battery positive electrode material is in the range of 1.50-2.20, the crystallinity of the positive electrode material is better, and the service life of the nickel-metal hydride battery positive electrode material is prolonged. The lithium ion battery is more stable in structure, smaller in electrode deformation during overcharging, better in cycle performance, more in proton migration channels and better in rate capability.

Description

Technical Field

[0001] The present application relates to the technical field of nickel-hydrogen batteries, and in particular to a nickel-hydrogen battery positive electrode material and a preparation method thereof, a nickel-hydrogen battery and electrical equipment. Background Art

[0002] Nickel-metal hydride batteries have the characteristics of low temperature performance, good cycle life, low maintenance cost, good safety, etc., and their application is becoming more and more extensive. Since the positive electrode material of nickel-metal hydride batteries has a direct impact on the performance of nickel-metal hydride batteries, the performance of nickel-metal hydride batteries can be further optimized by improving the positive electrode material of nickel-metal hydride batteries. Summary of the invention

[0003] The present application provides a nickel-hydrogen battery positive electrode material and a preparation method thereof, a nickel-hydrogen battery and electrical equipment to solve the problem of limited electrochemical performance of existing nickel-hydrogen battery positive electrode materials.

[0004] An embodiment of the present application provides a nickel-hydrogen battery positive electrode material, which is a nickel-containing hydroxide doped with cobalt, and the ratio of the grain size D(100) of the (100) crystal plane of the nickel-hydrogen battery positive electrode material to the grain size D(001) of the (001) crystal plane is D(100) / D(001)=1.50-2.20.

[0005] In some embodiments of the present application, in the positive electrode material of the nickel-hydrogen battery, the molar ratio of the cobalt element to the nickel element is 0.01-0.1:1;

[0006] In some embodiments of the present application, the nickel-hydrogen battery positive electrode material is further doped with zinc element, preferably, the molar ratio of zinc element to nickel element is 0.01-0.1:1;

[0007] In some embodiments of the present application, the chemical formula of the positive electrode material of the nickel-hydrogen battery is Ni x Co y M z (OH)2, wherein M is selected from at least one of Zn, Al, Ga, Mg, and Cu, 0.85≤x<0.96, 0.01 <y≤0.07,0≤z≤0.08,x+y+z=1。

[0008] In some embodiments of the present application, the positive electrode material of the nickel-hydrogen battery satisfies at least one of the following conditions:

[0009] a. The grain size of the (100) crystal plane of the nickel-hydrogen battery positive electrode material

[0010] b. The grain size of the (001) crystal plane of the nickel-hydrogen battery positive electrode material

[0011] c. The half-height width of the diffraction peak of the (100) crystal plane of the nickel-hydrogen battery positive electrode material is 0.300°-0.400°;

[0012] d. The half-height width of the diffraction peak of the (001) crystal plane of the nickel-hydrogen battery positive electrode material is 0.600°-0.800°;

[0013] e. The half-height width of the diffraction peak of the (101) crystal plane of the nickel-hydrogen battery positive electrode material is 0.800°-1.000°;

[0014] f. The peak intensity ratio of the (101) crystal plane to the (001) crystal plane of the nickel-hydrogen battery positive electrode material is I(101) / I(001)=0.500-0.700

[0015] g. In the nickel-hydrogen battery positive electrode material, D(100) / D(001)=1.70-2.15, preferably D(100) / D(001)=1.90-2.10.

[0016] In some embodiments of the present application, the positive electrode material of the nickel-hydrogen battery includes secondary particles composed of a plurality of primary particles, and the positive electrode material of the nickel-hydrogen battery satisfies at least one of the following conditions hk:

[0017] h. The secondary particles are spherical or quasi-spherical;

[0018] i. The average particle size D50 of the secondary particles is 9.0 μm-11.0 μm;

[0019] j. The specific surface area of ​​the secondary particles is 5m 2 / g-10m 2 / g;

[0020] k. The tap density of the secondary particles is 2.10 g / cm 3 -2.40g / cm 3 .

[0021] Another embodiment of the present application provides a method for preparing a positive electrode material for a nickel-hydrogen battery, comprising the following steps: mixing a solvent, a precipitant and a complexing agent to obtain a base liquid; adding a metal salt solution containing nickel and cobalt, a precipitant and a complexing agent to the base liquid for a co-precipitation reaction, maintaining the solid content of the reaction system at 140 g / L-350 g / L until a reaction product is obtained; and post-treating the reaction product to obtain a positive electrode material for a nickel-hydrogen battery.

[0022] In some embodiments of the present application, the preparation method satisfies at least one of the following conditions ①-⑧:

[0023] ①, the metal salt further contains an element M, wherein M is selected from at least one of Zn, Al, Ga, Mg, and Cu;

[0024] ②, the metal salt includes at least one of sulfate, nitrate, acetate and chloride;

[0025] ③. The total concentration of the metal salt solution is 110g / L-130g / L;

[0026] ④. The precipitant includes at least one of a sodium hydroxide solution and a potassium hydroxide solution;

[0027] ⑤. The mass percentage concentration of the precipitant is 20%-40%;

[0028] ⑥, the complexing agent includes at least one of ammonia water, ammonium bicarbonate solution, ammonium carbonate solution, EDTA solution (ethylenediaminetetraacetic acid solution), ethylenediamine solution, sodium citrate solution and ammonium sulfate solution;

[0029] ⑦. The mass percentage concentration of the complexing agent is 10%-30%;

[0030] ⑧. The solvent includes water.

[0031] In some embodiments of the present application, the temperature of the base liquid is 45°C-85°C; and / or the pH value of the base liquid is 10.00-12.00; and / or the complexing agent is ammonia water, and the ammonia concentration of the base liquid is 10g / L-20g / L.

[0032] In some embodiments of the present application, the preparation method satisfies at least one of the following conditions (1)-(8):

[0033] (1) The feeding rate of the metal salt solution is 5% / h-10% / h of the volume of the reaction vessel;

[0034] (2) The feed rate of the precipitant in the coprecipitation reaction is 2% / h-5% / h of the volume of the reaction vessel;

[0035] (3) The feeding rate of the complexing agent in the coprecipitation reaction is 0.1% / h-2% / h of the volume of the reaction container;

[0036] (4) The stirring speed of the coprecipitation reaction is 300r / min-800r / min;

[0037] (5) The reaction temperature of the coprecipitation reaction is the same as the temperature of the base solution and is 45° C.-85° C.;

[0038] (6) The reaction pH value of the coprecipitation reaction is the same as the pH value of the base solution and is 10.00-12.00;

[0039] (7) The complexing agent is ammonia water, and the ammonia concentration of the coprecipitation reaction is the same as the ammonia concentration of the base solution and is 10g / L-20g / L;

[0040] (8) The solid content of the reaction system of the coprecipitation reaction is 150 g / L-320 g / L.

[0041] Yet another embodiment of the present application provides a nickel-hydrogen battery, comprising any of the nickel-hydrogen battery positive electrode materials described above.

[0042] Another embodiment of the present application provides an electrical device, including the nickel-hydrogen battery described above.

[0043] The nickel-hydrogen battery positive electrode material provided in the embodiment of the present application, by doping cobalt elements in the positive electrode material, introducing defects and distortions in the lattice by doping elements, so that the mobility of protons is increased, which is beneficial to improve the charge and discharge efficiency, and cobalt can increase the oxygen evolution overpotential, which is beneficial to slow down the decay of the capacity and life of the positive electrode material at high temperature. In addition, the ratio of the grain size of the (100) crystal plane to the (001) crystal plane of the nickel-hydrogen battery positive electrode material is in the range of 1.50-2.20, at which time the positive electrode material has better crystallinity, more stable structure, less electrode deformation during overcharging, better cycle performance, and more proton migration channels, and better rate performance. Therefore, the nickel-hydrogen battery positive electrode material of the embodiment of the present application is doped with cobalt elements, and the ratio of the grain size D(100) / D(001) is controlled within the above-mentioned suitable range, which can be beneficial to take into account both cycle performance and rate performance while maintaining a higher capacity.

[0044] According to the method for preparing the positive electrode material of a nickel-hydrogen battery provided in the embodiment of the present application, by selecting a suitable metal salt raw material and controlling the steps and conditions of the coprecipitation reaction, the prepared positive electrode material of the nickel-hydrogen battery is a nickel-cobalt hydroxide, and the ratio of the grain size D(001) of the (100) crystal plane to the (001) crystal plane D(100) / D(001) is within a suitable range. Thus, by introducing the cobalt element into the nickel-containing hydroxide and controlling the ratio of the grain size D(100) / D(001) of the nickel-cobalt hydroxide within the above-mentioned suitable range, it is possible to maintain a relatively high capacity while balancing the cycle performance and rate performance.

[0045] The nickel-hydrogen battery provided according to the embodiment of the present application includes the nickel-hydrogen battery positive electrode material in the above embodiment. Based on the performance of the nickel-hydrogen battery positive electrode material, the nickel-hydrogen battery can take into account electrochemical properties such as cycle performance and rate performance.

[0046] Additional technical solutions and advantages of the present application will be partially given in the following description, and partially become apparent from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 This is a SEM image (3000 times) of the positive electrode material of the nickel-hydrogen battery provided in Example 3 of the present application;

[0049] Figure 2 This is a SEM image (10,000 times) of the positive electrode material for a nickel-hydrogen battery provided in Example 3 of the present application;

[0050] Figure 3 XRD diagram of the positive electrode material of the nickel-hydrogen battery provided in Example 3 of the present application;

[0051] Figure 4 This is a SEM image (3000 times) of the positive electrode material of a nickel-hydrogen battery provided in Example 4 of the present application;

[0052] Figure 5 This is a SEM image (10,000 times) of the positive electrode material for a nickel-hydrogen battery provided in Example 4 of the present application;

[0053] Figure 6 XRD diagram of the positive electrode material of the nickel-hydrogen battery provided in Example 4 of the present application;

[0054] Figure 7 This is a SEM image (3000 times) of the positive electrode material of a nickel-hydrogen battery provided in Example 6 of the present application;

[0055] Figure 8 This is a SEM image (10,000 times) of the positive electrode material for a nickel-hydrogen battery provided in Example 6 of the present application;

[0056] Fig. 9 This is the XRD diagram of the nickel-hydrogen battery positive electrode material provided in Example 6 of the present application. DETAILED DESCRIPTION

[0057] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0059] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0060] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0061] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0062] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0063] An embodiment of the present application provides a nickel-hydrogen battery positive electrode material, which is a nickel-hydride hydroxide doped with cobalt (Co), and the ratio of the grain size D(100) of the (100) crystal plane of the nickel-hydrogen battery positive electrode material to the grain size D(001) of the (001) crystal plane is D(100) / D(001)=1.50-2.20. Exemplarily, the ratio of the grain size D(100) of the (100) crystal plane of the nickel-hydrogen battery positive electrode material to the grain size D(001) of the (001) crystal plane, D(100) / D(001), can be 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20 or any value between 1.50 and 2.20.

[0064] The nickel-hydrogen battery positive electrode material provided in the embodiment of the present application, by doping cobalt elements in the positive electrode material, using the doping elements to introduce defects and distortions in the lattice, so that the mobility of protons is increased, which is beneficial to improve the charge and discharge efficiency, and cobalt can increase the oxygen evolution overpotential, which is beneficial to slow down the decay of the capacity and life of the positive electrode material at high temperature. In addition, the ratio of the grain size of the (100) crystal plane to the (001) crystal plane of the nickel-hydrogen battery positive electrode material is in the range of 1.50-2.20, at which time the positive electrode material has better crystallinity, more stable structure, less electrode deformation during overcharging, better cycle performance, and more proton migration channels, and better rate performance. Therefore, the nickel-hydrogen battery positive electrode material of the embodiment of the present application is doped with cobalt elements, and the ratio of the grain size D(100) / D(001) is controlled within the above-mentioned suitable range, which is beneficial to take into account both cycle performance and rate performance.

[0065] For example, in some embodiments, the grain size D(100) of the (100) crystal plane and the grain size D(001) of the (001) crystal plane of the positive electrode material of the nickel-hydrogen battery are measured by X-ray diffraction (XRD). Specifically, the grain size of the crystal plane is calculated by the following formula:

[0066] D = K·γ / (B·cosθ); where D is the average thickness of the grain perpendicular to the crystal plane, that is, the grain size; K is the Scherrer constant; B is the half-peak width or integrated width of the measured sample diffraction peak; θ is the Bragg angle; γ is the wavelength of the X-ray

[0067] When the grain size D(100) of the (100) crystal plane and the grain size D(001) of the (001) crystal plane of the nickel-hydrogen battery positive electrode material are within a suitable range, it is beneficial to further improve the performance of the nickel-hydrogen battery positive electrode material.

[0068] In some embodiments, the grain size of the (100) crystal plane of the nickel-hydrogen battery positive electrode material is For example, the grain size D(100) of the (100) crystal plane can be or By controlling the grain size D(100) of the (100) crystal plane of the positive electrode material of the nickel-hydrogen battery within the above-mentioned suitable range, D(100) is larger, and the number of proton migration channels is increased, which is conducive to further improving the rate performance.

[0069] In some embodiments, the grain size of the (001) crystal plane of the nickel-hydrogen battery positive electrode material is For example, the grain size D(001) of the (001) crystal plane can be or By controlling the grain size D(001) of the (001) crystal plane of the positive electrode material of the nickel-hydrogen battery within the above-mentioned suitable range, D(001) is larger, that is, the (001) crystal plane is larger, the structure is stable, which is conducive to reducing the electrode deformation during overcharging and improving the cycle performance.

[0070] Moreover, when the characteristics of the diffraction peaks of each crystal plane of the nickel-hydrogen battery positive electrode material obtained by XRD are within a suitable range, the nickel-hydrogen battery positive electrode material has better performance.

[0071] In some embodiments, the half-width (FWHM) (100) of the diffraction peak of the (100) crystal plane of the nickel-hydrogen battery positive electrode material is 0.300°-0.400°; illustratively, the half-width (FWHM) (100) of the diffraction peak of the (100) crystal plane can be 0.300°, 0.310°, 0.320°, 0.330°, 0.340°, 0.350°, 0.360°, 0.370°, 0.380°, 0.390°, 0.400° or any value between 0.300°-0.400°. In some embodiments, the half-width at half maximum FWHM (001) of the diffraction peak of the (001) crystal plane of the nickel-hydrogen battery positive electrode material is 0.600°-0.800°; illustratively, the half-width at half maximum FWHM (001) of the diffraction peak of the (001) crystal plane can be 0.600°, 0.620°, 0.640°, 0.660°, 0.680°, 0.700°, 0.720°, 0.740°, 0.760°, 0.780°, 0.800° or any value between 0.600°-0.800°. Therefore, by controlling the half-width of the diffraction peak of the (100) crystal plane and / or (001) crystal plane of the nickel-hydrogen battery positive electrode material within the above-mentioned appropriate range, the crystallinity is better and it is beneficial to obtain a nickel-hydrogen battery positive electrode material with a grain size ratio D(100) / D(001) that meets the requirements, thereby helping to improve the cycle performance and rate performance.

[0072] In some embodiments, the half-width FWHM (101) of the diffraction peak of the (101) crystal plane of the nickel-hydrogen battery positive electrode material is 0.800°-1.000°; illustratively, the half-width FWHM (101) of the diffraction peak of the (101) crystal plane can be 0.800°, 0.820°, 0.840°, 0.860°, 0.880°, 0.900°, 0.920°, 0.940°, 0.960°, 0.980°, 1.000° or any value between 0.800°-1.000°. In some embodiments, the peak intensity ratio of the (101) crystal plane to the (001) crystal plane of the nickel-hydrogen battery positive electrode material is I (101) / I (001) = 0.500-0.700. Exemplarily, the peak intensity ratio of the (101) crystal plane to the (001) crystal plane I(101) / I(001) can be 0.500, 0.520, 0.540, 0.560, 0.580, 0.600, 0.620, 0.640, 0.660, 0.680, 0.700 or any value between 0.500-0.700. Thus, by controlling the half-width of the diffraction peak of the (101) crystal plane of the positive electrode material of the nickel-hydrogen battery and the peak intensity ratio of the (101) crystal plane to the (001) crystal plane within the above-mentioned suitable range, the crystal plane growth mode can be optimized, so that the positive electrode material of the nickel-hydrogen battery has better crystallinity and more stable phase, so as to improve the rate performance and cycle performance at high temperature, and improve the capacity of the corresponding nickel-hydrogen battery.

[0073] In some embodiments, the positive electrode material of the nickel-hydrogen battery is also doped with zinc (Zn), that is, the positive electrode material of the nickel-hydrogen battery is a nickel hydroxide doped with cobalt and zinc. In this embodiment, the co-doping strategy of Co and Zn can more effectively exert the beneficial effects of each element on the electrochemical properties of the positive electrode material of the nickel-hydrogen battery.

[0074] Specifically, Co can increase the oxygen evolution overpotential, improve the problem of a sharp drop in the positive electrode oxygen evolution potential at high temperature, a decrease in the charging efficiency, and a decrease in the high-temperature cycle performance of the nickel-hydrogen battery, and can inhibit the occurrence of the oxygen evolution side reaction; in some embodiments, the molar ratio of cobalt to nickel in the positive electrode material of the nickel-hydrogen battery is 0.01-0.1:1. Zn will strengthen the Ni-O bond of the nickel hydroxide lattice and enhance the stability of the internal structure; in some embodiments, the positive electrode material of the nickel-hydrogen battery is also doped with zinc, and preferably, the molar ratio of zinc to nickel is 0.01-0.1:1. After the two elements Co and Zn are co-doped, the mobility of protons is increased by introducing defects and distortions in the lattice, which can significantly improve the charge and discharge efficiency and slow down the attenuation of the capacity and life of the positive electrode material at high temperature. Therefore, in some embodiments of the present application, by co-doping Co and Zn and the grain size ratio D(100) / D(001) is appropriate, the rate performance and high-temperature cycle performance are significantly improved, and both rate and cycle performance can be taken into account, and it has a good application prospect.

[0075] In some embodiments, D(100) / D(001)=1.70-2.15, preferably D(100) / D(001)=1.90-2.10 in the positive electrode material of the nickel-hydrogen battery, which can better balance the rate performance and cycle performance while maintaining a high capacity.

[0076] In some embodiments, the positive electrode material of the nickel-hydrogen battery includes secondary particles composed of a plurality of primary particles. In some embodiments, the secondary particles are spherical or quasi-spherical.

[0077] In some embodiments, the average particle size D50 of the secondary particles is 9.0 μm-11.0 μm. Wherein, D50 refers to the particle size corresponding to when the cumulative volume distribution percentage of the secondary particles of the positive electrode material of the nickel-hydrogen battery reaches more than 50%. The particle size is tested using a Malvern 3000 laser particle size analyzer, with reference to the standard GB / T 19077-2016. Exemplarily, the average particle size D50 of the secondary particles can be 9.0 μm, 9.2 μm, 9.4 μm, 9.6 μm, 9.8 μm, 10.0 μm, 10.2 μm, 10.4 μm, 10.6 μm, 10.8 μm, 11.0 μm or any value between 9.0 μm and 11.0 μm.

[0078] In some embodiments, the secondary particles have a BET surface area of ​​5 m 2 / g-10m 2 / g; wherein the specific surface area is determined according to GB / T 19587-2017 gas adsorption BET method for solid matter determination. Exemplarily, the specific surface area BET of the secondary particles can be 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g, 10m 2 / g or 5m 2 / g-10m 2 When the specific surface area of ​​the secondary particles is within the above suitable range, it is beneficial to reduce the side reaction between the positive electrode material and the electrolyte of the nickel-hydrogen battery.

[0079] In some embodiments, the tap density TD of the secondary particles is 2.10 g / cm 3 -2.40g / cm 3 ; The tap density TD is tested in accordance with GB / T 5162-2021 Determination of the tap density of metal powders. For example, the tap density TD of the secondary particles may be 2.10 g / cm 3 , 2.15g / cm 3 , 2.20g / cm3 , 2.25 g / cm 3 , 2.30 g / cm 3 , 2.35 g / cm 3 , 2.40 g / cm 3 or 2.10 g / cm 3 -2.40 g / cm 3 Any value between. When the tap density of the secondary particles is within the above suitable range, it is beneficial to improve the energy density of the nickel-metal hydride battery.

[0080] In some embodiments, the chemical general formula of the positive electrode material of the nickel-metal hydride battery is Ni x Co y M z (OH)2, where M is selected from at least one of Zn, Al, Ga, Mg, and Cu, 0.85 ≤ x < 0.96, 0.01 < y ≤ 0.07, 0 ≤ z ≤ 0.08, and x + y + z = 1. Exemplarily, in some embodiments, the chemical general formula of the positive electrode material of the nickel-metal hydride battery can be Ni 0.90 Co 0.05 Zn 0.05 (OH)2; in some embodiments, the chemical general formula of the positive electrode material of the nickel-metal hydride battery can be Ni 0.95 Co 0.05 (OH)2. In this embodiment, by further optimizing the doping element combination and ratio of the positive electrode material of the nickel-metal hydride battery, it is beneficial to achieve better structural stability and longer cycle life, so as to improve the electrochemical performance such as the rate performance and cycle performance of the nickel-metal hydride battery.

[0081] Another embodiment of the present application provides a method for preparing a positive electrode material of a nickel-metal hydride battery, including the following steps: mixing a solvent, a precipitant, and a complexing agent to obtain a bottom liquid; adding a metal salt solution containing nickel and cobalt, a precipitant, and a complexing agent to the bottom liquid for coprecipitation reaction, and controlling the solid content of the reaction system to be 140 g / L - 350 g / L by a concentrator until a reaction product is obtained; performing post-treatment on the reaction product to obtain the positive electrode material of the nickel-metal hydride battery. Among them, the solid content refers to the total mass of solids in the reaction system divided by the total volume of the reaction system, that is, the mass percentage of the remaining part after the reaction system is dried. Exemplarily, during the coprecipitation reaction, the solid content of the reaction system can be maintained at 140 g / L, 150 g / L, 180 g / L, 200 g / L, 220 g / L, 250 g / L, 300 g / L, 320 g / L, 350 g / L or any value between 100 g / L - 350 g / L.

[0082] According to the preparation method provided in the embodiment of the present application, by selecting a suitable metal salt raw material and controlling the steps and conditions of the coprecipitation reaction, the prepared nickel-hydrogen battery positive electrode material is a nickel-cobalt hydroxide, and the ratio of the grain size D(001) of the (100) crystal plane to the (001) crystal plane D(100) / D(001) is within a suitable range. Therefore, by introducing the cobalt element into the nickel-containing hydroxide and controlling the grain size ratio D(100) / D(001) of the nickel-cobalt hydroxide within the above-mentioned suitable range, it is beneficial to take into account both the cycle performance and the rate performance.

[0083] In some embodiments, the metal salt further contains an element M, wherein M is selected from at least one of Zn, Al, Ga, Mg, and Cu; in some embodiments, the metal salt includes at least one of sulfate, nitrate, acetate, and chloride; in some embodiments, the total concentration of the metal salt solution is 110 g / L-130 g / L; at this time, more suitable doping elements can be introduced through the metal salt to further improve the performance of the positive electrode material of the nickel-hydrogen battery.

[0084] In some embodiments, the precipitant includes at least one of sodium hydroxide solution and potassium hydroxide solution; in some embodiments, the mass percentage concentration of the precipitant is 20%-40%; in some embodiments, the complexing agent includes at least one of ammonia water, ammonium bicarbonate solution, ammonium carbonate solution, EDTA solution, ethylenediamine solution, sodium citrate solution and ammonium sulfate solution; in some embodiments, the mass percentage concentration of the complexing agent is 10%-30%; in some embodiments, the solvent includes water. In the above embodiments, selecting appropriate precipitants, complexing agents and solvents can effectively regulate reaction conditions such as pH value, so as to facilitate the reaction process of preparing the positive electrode material of the nickel-hydrogen battery, thereby obtaining a positive electrode material of the nickel-hydrogen battery that meets the target requirements.

[0085] In some embodiments, the temperature of the base solution is 45°C-85°C; in some embodiments, the pH value of the base solution is 10.00-12.00; in some embodiments, the complexing agent is ammonia water, and the ammonia concentration of the base solution is 10g / L-20g / L.

[0086] In some embodiments, the feed rate of the metal salt solution is 5% / h-10% / h of the volume of the reaction container; in some embodiments, the feed rate of the precipitant of the co-precipitation reaction is 2% / h-5% / h of the volume of the reaction container; in some embodiments, the feed rate of the complexing agent of the co-precipitation reaction is 0.1% / h-2% / h of the volume of the reaction container.

[0087] In some embodiments, the stirring speed of the co-precipitation reaction is 300r / min-800r / min; in some embodiments, the reaction temperature of the co-precipitation reaction is the same as the temperature of the base liquid and is 45°C-85°C; in some embodiments, the reaction pH value of the co-precipitation reaction is the same as the pH value of the base liquid and is 10.00-12.00; in some embodiments, the complexing agent is ammonia water, and the ammonia concentration of the co-precipitation reaction is the same as the ammonia concentration of the base liquid and is 10g / L-20g / L.

[0088] Since the nickel-hydrogen battery positive electrode material prepared in the embodiment of the present application contains doping elements such as cobalt, in order to ensure that the doping elements can play a better role in promoting the performance of the nickel-hydrogen battery positive electrode material as much as possible, it is necessary to strictly control the process conditions of the preparation process. Specifically, by controlling the process conditions of the preparation process within the above-mentioned appropriate range, it is beneficial to obtain a nickel-hydrogen battery positive electrode material that is effectively doped with elements such as cobalt and has a grain size ratio D(100) / D(001) that meets the requirements, so as to improve the electrochemical properties such as cycle performance and rate performance.

[0089] In some embodiments, the solid content of the reaction system of the coprecipitation reaction is 150 g / L-320 g / L, which is beneficial to further improve the electrochemical performance of the prepared nickel-hydrogen battery positive electrode material.

[0090] Another embodiment of the present application provides a nickel-hydrogen battery, including the nickel-hydrogen battery positive electrode material of any of the above embodiments. Exemplarily, the positive electrode of the nickel-hydrogen battery in the embodiment of the present application can be prepared using the nickel-hydrogen battery positive electrode material of the above embodiment, and the positive electrode is assembled with the negative electrode, the separator, etc. to form a nickel-hydrogen battery. Based on the performance of the nickel-hydrogen battery positive electrode material, the nickel-hydrogen battery in the embodiment of the present application can take into account electrochemical properties such as cycle performance and rate performance.

[0091] Yet another embodiment of the present application provides an electrical device, comprising the nickel-hydrogen battery of the above embodiment.

[0092] The following examples describe the disclosure of the present application in more detail, and these examples are merely illustrative, as it will be apparent to those skilled in the art that various modifications and variations are made within the scope of the disclosure of the present application. Unless otherwise stated, all reagents and raw materials used in the following examples are commercially available or synthesized according to conventional methods, and the instruments used in the examples are commercially available.

[0093] Example 1

[0094] This embodiment provides a nickel-hydrogen battery positive electrode material, whose chemical formula is Ni 0.90 Co 0.05 Zn 0.05 (OH)2. The preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0095] Raw material preparation: Prepare appropriate amounts of 120 g / L nickel sulfate solution, 120 g / L cobalt sulfate solution, and 120 g / L zinc sulfate solution. Mix appropriate amounts of nickel sulfate solution, cobalt sulfate solution, and zinc sulfate solution according to the molar ratio of Ni:Co:Zn=90.0:5.0:5.0 to prepare a metal salt solution with a concentration of 120 g / L.

[0096] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 60°C, the stirring speed was 450r / min, and the pH value was adjusted to 12.00 and the free ammonia concentration was 16.68g / L. Metal salt solution (flow rate is 7.75% / h of the volume of the reactor), sodium hydroxide solution (flow rate is 2.5-3.5% / h of the volume of the reactor) and ammonia water (flow rate is 0.40-0.80% / h of the volume of the reactor) are introduced into the reactor for coprecipitation reaction. The reaction slurry reaches the upper limit of the volume of the reactor and begins to overflow. The stirring speed of the reaction process is maintained at 450r / min. The pH value of the reaction process is controlled to be 12.00 by fine-tuning the flow rate of sodium hydroxide solution and ammonia water, and the free ammonia concentration is 16.68g / L. The solid content in the reactor is controlled to be 200g / L by a concentrator. Continue the reaction until a reaction product with a particle size D50 that meets the requirements is obtained. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.90 Co 0.05 Zn 0.05 (OH)2.

[0097] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.136 μm and a tap density of 2.12 g / cm 3 , with a specific surface area of ​​9.56m 2 / g.

[0098] The present embodiment also provides a method for preparing a nickel-hydrogen battery, comprising: (1) preparing a positive electrode sheet: mixing the prepared nickel-hydrogen battery positive electrode material with expanded graphite, carbonyl nickel powder and PTFE (polytetrafluoroethylene) in a mass ratio of 7:1:1:1 to form a slurry, applying the slurry on the nickel foam, pressing and forming the slurry with a roller press, drying and cutting the slurry, and finally welding the lugs and softening the slurry to obtain a positive electrode sheet; (2) preparing a negative electrode sheet: pressing and forming the AB5 alloy powder with a copper mesh as a carrier directly with a roller press, cutting the slurry, soaking the slurry in a 15% PTFE+CMC (carboxymethyl cellulose) aqueous solution and drying the slurry; (3) assembling a battery: winding the prepared positive electrode sheet, negative electrode sheet and diaphragm into a battery core and then loading the slurry into a battery steel shell, and then rolling the slurry, applying sealing oil, welding the battery cap and injecting electrolyte to seal the slurry, and finally completing the battery assembly by chemical sorting.

[0099] Electrochemical performance test: The electrochemical performance test of the nickel-hydrogen battery was carried out using a blue electric test system. The test voltage range is: 0.00-1.60V, 1C=200mAh / g. The preparation method of the nickel-hydrogen battery in the following examples and comparative examples is the same, and the electrochemical performance test method is also the same.

[0100] Example 2

[0101] The difference from Example 1 is that the stirring speed of the bottom liquid in the coprecipitation reaction and the stirring speed during the reaction are both 500 r / min.

[0102] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.468 μm and a tap density of 2.19 g / cm 3 , with a specific surface area of ​​8.62m 2 / g.

[0103] Example 3

[0104] The difference from Example 2 is that the solid content in the reactor of the coprecipitation reaction is controlled to be 320 g / L by a concentrator.

[0105] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.020 μm and a tap density of 2.32 g / cm 3 , with a specific surface area of ​​6.51m 2 / g.

[0106] Example 4

[0107] The difference from Example 2 is that the solid content in the reactor of the coprecipitation reaction is controlled to 260 g / L by a concentrator.

[0108] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 9.985 μm and a tap density of 2.25 g / cm 3 , with a specific surface area of ​​6.98m 2 / g.

[0109] Example 5

[0110] The difference from Example 4 is that the reaction temperature is 65°C.

[0111] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.331 μm and a tap density of 2.22 g / cm 3 , with a specific surface area of ​​7.01m 2 / g.

[0112] Example 6

[0113] The difference from Example 2 is that the pH value of the base liquid and the reaction process is 11.70, and the free ammonia concentration is 12.68 g / L.

[0114] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.056 μm and a tap density of 2.16 g / cm 3 , with a specific surface area of ​​8.77m 2 / g.

[0115] Example 7

[0116] The difference from Example 2 is that the positive electrode material of the nickel-hydrogen battery contains only the doping element Co and no Zn, and its chemical formula is Ni 0.95 Co 0.05 (OH)2.

[0117] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.347 μm and a tap density of 2.17 g / cm 3 , with a specific surface area of ​​8.44m 2 / g.

[0118] Example 8

[0119] The difference from Example 7 is that the solid content in the reactor of the coprecipitation reaction is controlled to be 320 g / L by a concentrator.

[0120] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 10.461 μm and a tap density of 2.30 g / cm 3 , with a specific surface area of ​​6.62m 2 / g.

[0121] Example 9

[0122] The difference from Example 7 is that the solid content in the reactor of the coprecipitation reaction is controlled to 260 g / L by a concentrator.

[0123] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this embodiment are spherical or quasi-spherical, with a particle size D50 of 9.865 μm and a tap density of 2.20 g / cm 3 , with a specific surface area of ​​7.25m 2 / g.

[0124] Comparative Example 1

[0125] The difference from Example 1 is that the preparation conditions of the positive electrode material of the nickel-hydrogen battery are different. Specifically, the preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0126] Raw material preparation: Prepare appropriate amounts of 120g / L nickel sulfate solution, 120g / L cobalt sulfate solution, and 120g / L zinc sulfate solution. Mix appropriate amounts of nickel sulfate solution, cobalt sulfate solution, and zinc sulfate solution, and prepare a metal salt solution with a concentration of 120g / L according to the molar ratio of Ni:Co:Zn=90.0:5.0:5.0.

[0127] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 60°C, the stirring speed was 500r / min, and the pH value was adjusted to 10.90 and the free ammonia concentration was 5.00g / L. A metal salt solution (with a flow rate of 7.75% / h of the volume of the reactor), a sodium hydroxide solution (with a flow rate of 2.5-3.5% / h of the volume of the reactor) and aqueous ammonia (with a flow rate of 0.40-0.80% / h of the volume of the reactor) were introduced into the reactor to carry out a coprecipitation reaction. During the reaction, an appropriate amount of seed crystals (the seed crystals were particles with the same chemical composition and a D50 of 2.0-3.0 μm) were added in batches. When D50 was less than 9.5 μm, an appropriate amount of seed crystals was added to maintain a D50 growth rate of 0.1-0.7 μm / hour. The reaction slurry reached the upper limit of the reactor volume and began to overflow. The stirring speed during the reaction process was maintained at 500 r / min. The pH value of the reaction process was controlled to be 10.90 by fine-tuning the flow rates of the sodium hydroxide solution and aqueous ammonia, the free ammonia concentration was 5.00 g / L, and the solid content in the reactor was 130 g / L. The particle size of the overflow material is D50 = 9.5-10.5 μm (add appropriate amount of seed crystals in batches to control D50 within the required range), and the overflow material is taken as the reaction product. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.90 Co 0.05Zn 0.05 (OH)2.

[0128] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this comparative example are spherical or quasi-spherical, with a particle size D50 of 10.145 μm and a tap density of 2.13 g / cm 3 , with a specific surface area of ​​9.24m 2 / g.

[0129] Comparative Example 2

[0130] The difference from Example 1 is that the preparation method and conditions of the positive electrode material of the nickel-hydrogen battery are different. Specifically, the preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0131] Raw material preparation: Prepare appropriate amounts of 120 g / L nickel sulfate solution, 120 g / L cobalt sulfate solution, and 120 g / L zinc sulfate solution. Mix appropriate amounts of nickel sulfate solution, cobalt sulfate solution, and zinc sulfate solution according to the molar ratio of Ni:Co:Zn=90.0:5.0:5.0 to prepare a metal salt solution with a concentration of 120 g / L.

[0132] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 75°C, the stirring speed was 500r / min, and the pH value was adjusted to 10.60 and the free ammonia concentration was 16.68g / L. A metal salt solution (with a flow rate of 7.75% / h of the volume of the reactor), a sodium hydroxide solution (with a flow rate of 2.5-3.5% / h of the volume of the reactor) and aqueous ammonia (with a flow rate of 0.40-0.80% / h of the volume of the reactor) were introduced into the reactor to carry out a coprecipitation reaction. During the reaction, an appropriate amount of seeds (the seeds were particles with the same chemical composition and a D50 of 2.0-3.0 μm) were added in batches. When D50 was less than 9.5 μm, an appropriate amount of seeds were added to maintain a D50 growth rate of 0.1-0.7 μm / hour. The reaction slurry reached the upper limit of the reactor volume and began to overflow. The stirring speed during the reaction was maintained at 500 r / min. The pH value of the reaction process was controlled to be 10.60 by fine-tuning the flow rates of the sodium hydroxide solution and aqueous ammonia, the free ammonia concentration was 16.68 g / L, and the solid content in the reactor was 130 g / L. The particle size of the overflow material is D50 = 9.5-10.5 μm (add appropriate amount of seed crystals in batches to control D50 within the required range), and the overflow material is taken as the reaction product. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.90 Co 0.05 Zn 0.05 (OH)2.

[0133] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this comparative example are spherical or quasi-spherical, with a particle size D50 of 10.132 μm and a tap density of 2.10 g / cm 3 , with a specific surface area of ​​10.81m 2 / g.

[0134] Comparative Example 3

[0135] The difference from Example 1 is that the preparation method and conditions of the positive electrode material of the nickel-hydrogen battery are different. Specifically, the preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0136] Raw material preparation: Prepare appropriate amounts of 120 g / L nickel sulfate solution, 120 g / L cobalt sulfate solution, and 120 g / L zinc sulfate solution. Mix appropriate amounts of nickel sulfate solution, cobalt sulfate solution, and zinc sulfate solution according to the molar ratio of Ni:Co:Zn=90.0:5.0:5.0 to prepare a metal salt solution with a concentration of 120 g / L.

[0137] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 75°C, the stirring speed was 500r / min, and the pH value was adjusted to 10.30 and the free ammonia concentration was 7.20g / L. A metal salt solution (with a flow rate of 7.75% / h of the volume of the reactor), a sodium hydroxide solution (with a flow rate of 2.5-3.5% / h of the volume of the reactor) and aqueous ammonia (with a flow rate of 0.40-0.80% / h of the volume of the reactor) were introduced into the reactor to carry out a coprecipitation reaction. During the reaction, an appropriate amount of seeds (the seeds were particles with the same chemical composition and a D50 of 2.0-3.0 μm) were added in batches. When D50 was less than 9.5 μm, an appropriate amount of seeds were added to maintain a D50 growth rate of 0.1-0.7 μm / hour. The reaction slurry reached the upper limit of the reactor volume and began to overflow. The stirring speed during the reaction was maintained at 500 r / min. The pH value of the reaction process was controlled to be 10.30 by fine-tuning the flow rates of the sodium hydroxide solution and aqueous ammonia, the free ammonia concentration was 7.20 g / L, and the solid content in the reactor was 130 g / L. The particle size of the overflow material is D50 = 9.5-10.5 μm (add appropriate amount of seed crystals in batches to control D50 within the required range), and the overflow material is taken as the reaction product. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.90 Co 0.05 Zn 0.05 (OH)2.

[0138] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this comparative example are spherical or quasi-spherical, with a particle size D50 of 10.211 μm and a tap density of 2.08 g / cm3 , with a specific surface area of ​​12.15m 2 / g.

[0139] Comparative Example 4

[0140] The difference from Example 7 is that the preparation conditions of the positive electrode material of the nickel-hydrogen battery are different. Specifically, the preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0141] Raw material preparation: Prepare an appropriate amount of 120g / L nickel sulfate solution and 120g / L cobalt sulfate solution. Mix an appropriate amount of nickel sulfate solution and cobalt sulfate solution according to the molar ratio of Ni:Co=95.0:5.0 to prepare a metal salt solution with a concentration of 120g / L.

[0142] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 60°C, the stirring speed was 500r / min, and the pH value was adjusted to 10.90 and the free ammonia concentration was 5.00g / L. A metal salt solution (with a flow rate of 7.75% / h of the volume of the reactor), a sodium hydroxide solution (with a flow rate of 2.5-3.5% / h of the volume of the reactor) and aqueous ammonia (with a flow rate of 0.40-0.80% / h of the volume of the reactor) were introduced into the reactor to carry out a coprecipitation reaction. During the reaction, an appropriate amount of seed crystals (the seed crystals were particles with the same chemical composition and a D50 of 2.0-3.0 μm) were added in batches. When D50 was less than 9.5 μm, an appropriate amount of seed crystals was added to maintain a D50 growth rate of 0.1-0.7 μm / hour. The reaction slurry reached the upper limit of the reactor volume and began to overflow. The stirring speed during the reaction process was maintained at 500 r / min. The pH value of the reaction process was controlled to be 10.90 by fine-tuning the flow rates of the sodium hydroxide solution and aqueous ammonia, the free ammonia concentration was 5.00 g / L, and the solid content in the reactor was 130 g / L. The particle size of the overflow material is D50 = 9.5-10.5 μm (add appropriate amount of seed crystals in batches to control D50 within the required range), and the overflow material is taken as the reaction product. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.95 Co 0.05 (OH)2.

[0143] The secondary particles of the positive electrode material of the nickel-hydrogen battery prepared in this comparative example are spherical or quasi-spherical, with a particle size D50 of 9.954 μm and a tap density of 2.11 g / cm 3 , the specific surface area is 11.80m 2 / g.

[0144] Comparative Example 5

[0145] The difference from Example 7 is that the preparation conditions of the positive electrode material of the nickel-hydrogen battery are different. Specifically, the preparation method of the positive electrode material of the nickel-hydrogen battery includes:

[0146] Raw material preparation: Prepare an appropriate amount of 120g / L nickel sulfate solution and 120g / L cobalt sulfate solution. Mix an appropriate amount of nickel sulfate solution and cobalt sulfate solution according to the molar ratio of Ni:Co=95.0:5.0 to prepare a metal salt solution with a concentration of 120g / L.

[0147] Co-precipitation reaction: pure water, sodium hydroxide solution (mass percentage concentration of 20.5%), and ammonia solution (mass percentage concentration of 10.5%) were added into the reactor as the base liquid, and nitrogen was introduced as the protective gas. The reaction temperature was 75°C, the stirring speed was 500r / min, and the pH value was adjusted to 10.60 and the free ammonia concentration was 5.00g / L. A metal salt solution (with a flow rate of 7.75% / h of the volume of the reactor), a sodium hydroxide solution (with a flow rate of 2.5-3.5% / h of the volume of the reactor) and aqueous ammonia (with a flow rate of 0.40-0.80% / h of the volume of the reactor) were introduced into the reactor to carry out a coprecipitation reaction. During the reaction, an appropriate amount of seed crystals (the seed crystals were particles with the same chemical composition and a D50 of 2.0-3.0 μm) were added in batches. When D50 was less than 9.5 μm, an appropriate amount of seed crystals was added to maintain a D50 growth rate of 0.1-0.7 μm / hour. The reaction slurry reached the upper limit of the reactor volume and began to overflow. The stirring speed during the reaction process was maintained at 500 r / min. The pH value of the reaction process was controlled to be 10.90 by fine-tuning the flow rates of the sodium hydroxide solution and aqueous ammonia, the free ammonia concentration was 5.00 g / L, and the solid content in the reactor was 130 g / L. The particle size of the overflow material is D50 = 9.5-10.5 μm (add appropriate amount of seed crystals in batches to control D50 within the required range), and the overflow material is taken as the reaction product. The reaction product is filtered and washed, and the filter cake is dried, sieved, and demagnetized to obtain Ni 0.95 Co 0.05 (OH)2.

[0148] The secondary particles of the nickel-hydrogen battery positive electrode material prepared in this comparative example are spherical or quasi-spherical, with a particle size D50 of 9.883 μm and a tap density of 2.05 g / cm 3 , with a specific surface area of ​​12.37m 2 / g.

[0149] Table 1. Physical and chemical properties of the positive electrode materials of nickel-hydrogen batteries in various embodiments and comparative examples

[0150]

[0151]

[0152] Table 2 Electrochemical properties of the positive electrode materials for nickel-hydrogen batteries of various embodiments and comparative examples

[0153]

[0154] According to Table 1 and Table 2, Comparative Examples 1 to 3 adopt a co-doping method different from the embodiment of the present application to prepare the positive electrode material of the nickel-hydrogen battery, and cannot take into account both the rate performance and the high-temperature cycle performance. Specifically, compared with Examples 1 to 6, Comparative Example 1 has a positive electrode material co-doped with cobalt and zinc elements, and the grain size ratio D(100) / D(001) is too small, and the positive electrode materials of Comparative Examples 2 and Comparative Examples 3 are co-doped with cobalt and zinc elements, and the grain size ratio D(100) / D(001) is too large, and the corresponding rate performance and high-temperature cycle performance are significantly lower than those of Examples 1 to 6.

[0155] Compared with Examples 7 to 9, the grain size ratio D(100) / D(001) of Comparative Example 4 is too small, and compared with Examples 7 to 9, the grain size ratio D(100) / D(001) of Comparative Example 5 is too large, and the corresponding rate performance and high temperature cycle performance are significantly lower than those of Examples 7 to 9. It can be seen that the present invention significantly improves the rate performance and high temperature cycle performance by doping elements such as Co and controlling the grain size ratio D(100) / D(001) within a suitable range, indicating that doping elements such as Co and controlling the appropriate grain size ratio D(100) / D(001) can take into account both rate and cycle performance.

[0156] Examples 1 to 6 all adopt the method of co-doping Co and Zn elements to prepare the positive electrode material of nickel-hydrogen battery. Compared with Example 6, Example 3 shows that the D(100) / D(001) of Example 3 is in the better range of 1.9-2.1, which further improves the rate performance and high temperature cycle performance. Specifically, the rate capacity retention rate is increased from 69.4% to 74.3%, an increase of 4.9%. At high temperature, 1C cycles 200 times, and the capacity retention rate is increased from 79.9% to 82.1%, an increase of 2.2%. The above differences may be due to the fact that the (001) grain size becomes larger, which is more conducive to structural stability, the electrode deformation is reduced during overcharging, and the cycle performance is improved, but it will affect the rate performance improvement; the (100) crystal plane becomes larger, and the proton migration channels increase, which is beneficial to the rate performance improvement, but it will affect the cycle performance. The embodiments of the present application select appropriate doping elements and control the ratio range of the grain size to give full play to their respective advantages and achieve better comprehensive effects. It can be seen from the above that the cobalt-containing nickel-hydrogen battery positive electrode material prepared based on the present application has electrochemical properties such as good cycle performance and rate performance while maintaining a relatively high capacity.

[0157] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A nickel-hydrogen battery positive electrode material, characterized in that: The nickel-hydrogen battery positive electrode material is a nickel hydroxide doped with cobalt, and the ratio of the grain size D(100) of the (100) crystal plane of the nickel-hydrogen battery positive electrode material to the grain size D(001) of the (001) crystal plane is D(100) / D(001)=1.50-2.

20.

2. The positive electrode material for nickel-hydrogen batteries according to claim 1, characterized in that: The nickel-hydrogen battery positive electrode material meets at least one of the following conditions: (1) In the positive electrode material of nickel-hydrogen batteries, the molar ratio of cobalt to nickel is 0.01-0.1:1; (2) The nickel-hydrogen battery positive electrode material is also doped with zinc, preferably, the molar ratio of zinc to nickel is 0.01-0.1:1; (3) The chemical formula of the positive electrode material of the nickel-hydrogen battery is Ni x Co y M z (OH)2, wherein M is selected from at least one of Zn, Al, Ga, Mg, and Cu, 0.85≤x<0.96, 0.01 <y≤0.07,0≤z≤0.08,x+y+z=1。 3. The positive electrode material for nickel-hydrogen batteries according to claim 1, characterized in that: The nickel-hydrogen battery positive electrode material meets at least one of the following conditions: a. The grain size of the (100) crystal plane of the nickel-hydrogen battery positive electrode material b. The grain size of the (001) crystal plane of the nickel-hydrogen battery positive electrode material c. The half-height width of the diffraction peak of the (100) crystal plane of the nickel-hydrogen battery positive electrode material is 0.300°-0.400°; d. The half-height width of the diffraction peak of the (001) crystal plane of the nickel-hydrogen battery positive electrode material is 0.600°-0.800°; e. The half-height width of the diffraction peak of the (101) crystal plane of the nickel-hydrogen battery positive electrode material is 0.800°-1.000°; f. The peak intensity ratio of the (101) crystal plane to the (001) crystal plane of the nickel-hydrogen battery positive electrode material is I(101) / I(001)=0.500-0.700; g. In the nickel-hydrogen battery positive electrode material, D(100) / D(001)=1.70-2.15, preferably D(100) / D(001)=1.90-2.

10.

4. The positive electrode material for nickel-hydrogen batteries according to claim 1, characterized in that: The nickel-hydrogen battery positive electrode material comprises secondary particles composed of a plurality of primary particles, and the nickel-hydrogen battery positive electrode material satisfies at least one of the following conditions hk: h. The secondary particles are spherical or quasi-spherical; i. The average particle size D50 of the secondary particles is 9.0 μm-11.0 μm; j. The specific surface area of ​​the secondary particles is 5m 2 / g-10m 2 / g; k. The tap density of the secondary particles is 2.10 g / cm 3 -2.40g / cm 3 .

5. A method for preparing a positive electrode material for a nickel-hydrogen battery, characterized in that: The following steps are involved: mixing a solvent, a precipitant and a complexing agent to obtain a base solution; Adding a metal salt solution containing nickel and cobalt, a precipitant, and a complexing agent to the base liquid to carry out a coprecipitation reaction, maintaining the solid content of the reaction system at 140 g / L-350 g / L until a reaction product is obtained; The reaction product is post-processed to obtain a positive electrode material for a nickel-hydrogen battery.

6. The method for preparing the positive electrode material of a nickel-hydrogen battery according to claim 5, characterized in that: The preparation method satisfies at least one of the following conditions ①-⑧: ①, the metal salt further contains an element M, wherein M is selected from at least one of Zn, Al, Ga, Mg, and Cu; ②, the metal salt includes at least one of sulfate, nitrate, acetate and chloride; ③. The total concentration of the metal salt solution is 110g / L-130g / L; ④. The precipitant includes at least one of a sodium hydroxide solution and a potassium hydroxide solution; ⑤. The mass percentage concentration of the precipitant is 20%-40%; ⑥, the complexing agent includes at least one of ammonia water, ammonium bicarbonate solution, ammonium carbonate solution, EDTA solution, ethylenediamine solution, sodium citrate solution and ammonium sulfate solution; ⑦. The mass percentage concentration of the complexing agent is 10%-30%; ⑧. The solvent includes water.

7. The method for preparing the positive electrode material of a nickel-hydrogen battery according to claim 5, characterized in that: The temperature of the base liquid is 45°C-85°C; and / or The pH value of the base liquid is 10.00-12.00; and / or The complexing agent is ammonia water, and the ammonia concentration of the base solution is 10g / L-20g / L.

8. The method for preparing the positive electrode material of a nickel-hydrogen battery according to claim 5, characterized in that: The preparation method satisfies at least one of the following conditions (1)-(8): (1) The feeding rate of the metal salt solution is 5% / h-10% / h of the volume of the reaction vessel; (2) The feed rate of the precipitant in the coprecipitation reaction is 2% / h-5% / h of the volume of the reaction vessel; (3) The feeding rate of the complexing agent in the coprecipitation reaction is 0.1% / h-2% / h of the volume of the reaction container; (4) The stirring speed of the coprecipitation reaction is 300r / min-800r / min; (5) The reaction temperature of the coprecipitation reaction is the same as the temperature of the base solution and is 45° C.-85° C.; (6) The reaction pH value of the coprecipitation reaction is the same as the pH value of the base solution and is 10.00-12.00; (7) The complexing agent is ammonia water, and the ammonia concentration of the coprecipitation reaction is the same as the ammonia concentration of the base solution and is 10g / L-20g / L; (8) The solid content of the reaction system of the coprecipitation reaction is 150 g / L-320 g / L.

9. A nickel-hydrogen battery, characterized in that: The nickel-hydrogen battery positive electrode material comprises any one of claims 1-8.

10. An electrical equipment, characterized in that: Including the nickel-hydrogen battery as claimed in claim 9.

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