WO2024114720A1 - Matériau d'électrode positive, son procédé de préparation et son utilisation - Google Patents

Matériau d'électrode positive, son procédé de préparation et son utilisation Download PDF

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WO2024114720A1
WO2024114720A1 PCT/CN2023/135336 CN2023135336W WO2024114720A1 WO 2024114720 A1 WO2024114720 A1 WO 2024114720A1 CN 2023135336 W CN2023135336 W CN 2023135336W WO 2024114720 A1 WO2024114720 A1 WO 2024114720A1
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positive electrode
electrode material
nickel hydroxide
phase nickel
phase
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PCT/CN2023/135336
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English (en)
Chinese (zh)
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赵东元
晁栋梁
周万海
严睿婷
杨阳宇尘
陈顺鹏
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华为技术有限公司
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Publication of WO2024114720A1 publication Critical patent/WO2024114720A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/24—Electrodes for alkaline accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/30—Nickel accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy

Definitions

  • the embodiments of the present application relate to the technical field of nickel-based batteries, and specifically to a positive electrode material and a preparation method and application thereof.
  • Nickel-based alkaline batteries have been successfully applied in portable consumer products, new energy vehicles, large-scale energy storage equipment, etc. due to their advantages of high safety, low cost, environmental friendliness, and high power density.
  • ⁇ -phase nickel hydroxide is the widely used positive electrode active material in commercial nickel-based alkaline batteries, but its intrinsic conductivity is low and it is easy to release oxygen during battery operation.
  • the industry usually uses cobalt-based materials for coating modification or mechanical addition modification to improve the rate performance and coulomb efficiency of electrode materials, but the price of cobalt-based materials is expensive, which increases the cost of nickel-based alkaline batteries.
  • ⁇ -phase nickel hydroxide has attracted extensive attention in recent years due to its high theoretical specific capacity (about 482 mAh/g). It also has a certain effect of inhibiting oxygen evolution on ⁇ -phase nickel hydroxide materials, but its intrinsic density is low.
  • the tap density of the ⁇ -phase nickel hydroxide actually prepared is usually much lower than 1.6 g/cm 3 , which cannot meet the market demand for high volume energy density batteries. People expect to prepare ⁇ -phase/ ⁇ -phase nickel hydroxide composite materials to take into account high tap density, high coulomb efficiency, high specific capacity, etc.
  • the coating layer of the coated composite material of ⁇ -phase nickel hydroxide and ⁇ -phase nickel hydroxide obtained by coprecipitation is usually loose, which will significantly reduce the tap density of the composite material and deteriorate the electrochemical performance of the material due to the easy detachment of the coating layer. Therefore, it is necessary to provide a nickel-based battery positive electrode material with high tap density and good electrochemical performance and its preparation.
  • an embodiment of the present application provides a positive electrode material, a preparation method and an application thereof.
  • the positive electrode material uses an ⁇ -phase nickel hydroxide material to tightly coat a ⁇ -phase nickel hydroxide, and controls its mass proportion in the composite material to not exceed 9%.
  • the positive electrode material can have good electrochemical properties such as high tap density, high coulombic efficiency, and high specific capacity.
  • a first aspect of an embodiment of the present application provides a positive electrode material, comprising a core and a shell coated on the surface of the core, wherein the core comprises a ⁇ -phase nickel hydroxide material, and the shell comprises an ⁇ -phase nickel hydroxide material, wherein there are pores between at least some particles of the ⁇ -phase nickel hydroxide material, and the average pore size of the pores is 1-50 nm; the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material is less than 9wt%.
  • the pores with an average pore size of 1-50nm in the shell layer can reflect that the ⁇ -phase nickel hydroxide material is tightly stacked on the surface of the core 101, and its mass accounts for a relatively small proportion, which is conducive to a significant increase in the tap density of the positive electrode material.
  • the tight stacking/coating of the ⁇ -phase nickel hydroxide material can better inhibit the oxygen evolution reaction of the core material during the charge and discharge process, which is conducive to the improvement of the coulombic efficiency of the material, and solves the problem of easy oxygen evolution of the nickel hydroxide positive electrode material by relying on the addition of a large amount of high-cost cobalt.
  • the tight coating of the core by the ⁇ -phase nickel hydroxide material with certain electrochemical activity is also conducive to promoting the actual capacity of the ⁇ -phase nickel hydroxide material, which can greatly improve the specific capacity and coulombic efficiency of the overall positive electrode material.
  • the molar ratio of cobalt to nickel in the positive electrode material is less than 1%.
  • the cobalt content in the positive electrode material is low, the manufacturing cost is low, and the effect of the shell layer in suppressing oxygen evolution in the core is not weaker than when a large amount of cobalt is added. Therefore, the positive electrode material can take into account low cost, high tap density and good electrochemical performance.
  • the pore volume of the shell layer is less than or equal to 0.2 cm 3 /g.
  • the smaller pore volume reflects the close packing of the ⁇ -phase nickel hydroxide material on the surface of the core, which is beneficial for the positive electrode material to have both high tap density and high coulombic efficiency.
  • the shell layer is formed by stacking a plurality of primary particles of the ⁇ -phase nickel hydroxide material, and the primary particles of the ⁇ -phase nickel hydroxide material are nanosheets with a thickness of 5nm-20nm.
  • the primary particles of the ⁇ -phase nickel hydroxide material are nanosheets with a relatively thin thickness, which is more conducive to the transmission of ions, electrons, etc. in the positive electrode material, and can greatly improve the kinetic properties of the positive electrode material and improve its high rate performance.
  • the specific surface area of the positive electrode material is 0.5-30m2 /g. After the ⁇ -phase nickel hydroxide is coated with the ⁇ -phase nickel hydroxide material, the specific surface area is increased to a certain extent, and the shell layer of the obtained positive electrode material is more densely distributed than the coating layer material prepared by the conventional coprecipitation method, and the specific surface area is not excessively increased, which can better take into account the high tap density and high rate output capacity, and is conducive to improving the effect of inhibiting oxygen evolution.
  • the coverage of the ⁇ -phase nickel hydroxide material is greater than or equal to 90%.
  • This parameter can reflect that the ⁇ -phase nickel hydroxide material is evenly distributed on the surface of the core, avoiding the uneven coating problem caused by the conventional secondary deposition technology.
  • the tap density of the positive electrode material is greater than or equal to 1.8 g/cm 3 .
  • the tight coating of the ⁇ -phase nickel hydroxide material with a relatively small mass percentage can ensure that the tap density of the positive electrode material is relatively high.
  • the tap density of the positive electrode material is 1.8 g/cm 3 -2.4 g/cm 3 .
  • a second aspect of the present application provides a method for preparing a positive electrode material, comprising the following steps:
  • a ⁇ -phase nickel hydroxide raw material is mixed with a reaction solution containing a soluble salt of a first non-nickel metal element M and a soluble salt of an anion Q, and an ion permeation self-exchange reaction is performed to obtain a positive electrode material; wherein the positive electrode material comprises a core and a shell coated on the surface of the core, the core comprises a ⁇ -phase nickel hydroxide material, the shell comprises an ⁇ -phase nickel hydroxide material, at least some particles of the ⁇ -phase nickel hydroxide material have pores, the average pore size of the pores is 1-50nm, and the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material is less than 9wt%; the M comprises one or more of Al, Fe, Mn, Y, and Yb, and the Q comprises one or more of CO 3 2- , SO 4 2- , NO 3 - , Cl - , and Br - .
  • the temperature of the ion permeation self-exchange reaction is 50° C.-120° C., and the reaction time is 1-24 hours.
  • the ratio of the mass of the ⁇ -phase nickel hydroxide raw material to the volume of the reaction solution is 1: (3-100) kg/L.
  • a suitable solid-liquid ratio can ensure that the coating thickness and coating compactness of the shell layer in the positive electrode material are appropriate, and improve the preparation efficiency of the above-mentioned positive electrode material.
  • the Q at least includes CO 3 2- .
  • Carbonate can better ensure the smooth generation of the ⁇ -phase nickel hydroxide, and improve its structural stability and ion conductivity, thereby giving the positive electrode material good rate performance and cycle performance.
  • the concentration of the soluble salt of the metal element M or the soluble salt of the anion Q does not exceed 3.0 mol/L. This helps to ensure that the ⁇ -phase nickel hydroxide has a suitable generation rate and can regulate its content in the positive electrode material.
  • the chemical formula of the ⁇ -phase nickel hydroxide raw material is Ni 1-x' A' x' (OH) 2 , wherein 0 ⁇ x' ⁇ 0.15, A' is a non-nickel metal element, including one or more of Zn, Mg, Ca, Ba, Al, Fe, Mn, Y or Yb, but does not contain Co.
  • the chemical formula of the ⁇ -phase nickel hydroxide material includes Ni 1-x A x (OH) 2 , wherein 0 ⁇ x ⁇ 0.15, A includes A', and the 1-x gradient increases to 1-x' from the shell layer toward the core;
  • the chemical formula of the ⁇ -phase nickel hydroxide material includes Ni 1-y M y (OH) 2-z Q z ⁇ nH 2 O, wherein 0 ⁇ y ⁇ 0.3, 0 ⁇ z ⁇ 0.1, 0 ⁇ n ⁇ 1, and the y gradient in the shell layer decreases from the shell layer toward the core.
  • the preparation method of the positive electrode material is simple in process, low in cost, and suitable for large-scale batch production.
  • the prepared positive electrode material can ensure good electrochemical performance and high tap density in the absence of cobalt.
  • the third aspect of the embodiment of the present application provides a positive electrode plate, comprising the positive electrode material described in the first aspect of the embodiment of the present application, or the positive electrode material prepared by the preparation method described in the second aspect of the embodiment of the present application.
  • the positive electrode plate can have advantages such as high compaction density, good stability, and high capacity.
  • the fourth aspect of the embodiment of the present application provides an alkaline storage battery, comprising a positive electrode, a negative electrode, and an electrolyte and a separator located between the positive electrode and the negative electrode, wherein the positive electrode comprises the positive electrode sheet described in the third aspect of the embodiment of the present application.
  • the alkaline storage battery has a high volume energy density, high coulombic efficiency and specific capacity, and good cycle performance.
  • the embodiments of the present application also provide an electronic device or an energy storage system using the above alkaline battery.
  • FIG1 is a schematic diagram of the structure of a positive electrode material provided in an embodiment of the present application.
  • FIG. 2 is a schematic diagram of the structure of the positive electrode plate provided in an embodiment of the present application.
  • FIG. 3 is a schematic diagram of the structure of a battery provided in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application.
  • FIG5 is a schematic diagram of the structure of an energy storage system provided in an embodiment of the present application.
  • FIG6 summarizes the X-ray diffraction patterns of the uncoated ⁇ -phase cobalt-free spherical nickel hydroxide material of Comparative Example 1 and the positive electrode material prepared in Example 1.
  • FIG7 is a scanning electron microscope (SEM) image of the uncoated ⁇ -phase nickel hydroxide material.
  • FIG8 is a SEM image of a positive electrode material obtained by coating a ⁇ -phase nickel hydroxide material using the method of Example 1.
  • FIG. 9 is a cross-sectional scanning electron microscope-energy dispersive spectrometer characterization result of the positive electrode material prepared in Example 1.
  • FIG10 is a comparison diagram of cyclic voltammetry curves of nickel-zinc half-cells made using the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 and the coated positive electrode material of Example 1.
  • FIG11 is a comparison chart of the charge and discharge curves of nickel-zinc half-cells made using the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 and the coated positive electrode material of Example 1.
  • FIG12 is a rate discharge curve of a nickel-zinc half-cell made using the coated positive electrode material of Example 1.
  • FIG. 13 is a comparison chart of the rate performance of nickel-zinc half-cells made using the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 and the coated positive electrode material of Example 1.
  • FIG. 14 is a comparison chart of the cycle performance of nickel-zinc half-cells made using the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 and the coated positive electrode material of Example 1.
  • FIG. 1 is a schematic diagram of a structure of a positive electrode material 100 provided in an embodiment of the present application.
  • the positive electrode material 100 provided in an embodiment of the present application includes a core 101 and a shell 102 coated on the surface of the core 101, the core 101 includes a ⁇ -phase nickel hydroxide material, and the shell 102 includes an ⁇ -phase nickel hydroxide material, wherein the shell 102 is formed by stacking a plurality of nano-sheet primary particles 1021 of the ⁇ -phase nickel hydroxide material, and the shell 102 has a porous structure with an average pore size of 5-50 nm; the molar ratio of cobalt element (Co) to nickel element (Ni) in the positive electrode material 100 is less than 1%; the mass proportion of ⁇ -phase nickel hydroxide material in the positive electrode material 100 is less than 9wt%.
  • Co cobalt element
  • Ni nickel element
  • the ⁇ -phase nickel hydroxide material is coated with the ⁇ -phase nickel hydroxide material.
  • the ⁇ -phase nickel hydroxide material particles in the embodiment of the present application are accumulated on the surface of the core, resulting in a smaller average pore size of the pores between the particles, which can reflect that the ⁇ -phase nickel hydroxide material in the shell layer 102 is tightly accumulated on the surface of the core 101, and the effect of inhibiting the oxygen evolution reaction of the core material during the charge and discharge process can be significantly improved, which is conducive to a substantial improvement in the coulomb efficiency, and the corresponding cycle performance of the positive electrode material 100 is also improved to a certain extent.
  • the ⁇ -phase nickel hydroxide material is used as both a functional layer and an active layer, and can play a synergistic role with the core ⁇ -phase nickel hydroxide material, which is conducive to improving the actual capacity of the ⁇ -phase nickel hydroxide material, so that the capacity of the overall positive electrode material 100 is greater than the simple sum of the ⁇ -phase nickel hydroxide material and the ⁇ -phase nickel hydroxide material, and the coulomb efficiency of the positive electrode material 100 can also be further improved accordingly.
  • the shell layer 102 is tightly coated, its combination with the core is relatively firm, and it is not easy to deteriorate the electrochemical properties of the material due to shedding.
  • the above-mentioned positive electrode material 100 can combine the advantages of ⁇ -phase nickel hydroxide material such as high tap density and ⁇ -phase nickel hydroxide material such as high specific capacity, and the tight coating of the shell material can make the core/shell material play a certain synergistic effect, so that the positive electrode material 100 has high tap density, high coulomb efficiency, high specific capacity and good rate performance.
  • the core 101 is a ⁇ -phase nickel hydroxide material particle
  • the shell 102 is formed by the ⁇ -phase nickel hydroxide material tightly stacked on the surface of the core 101.
  • the mass of the shell material is less than 9wt% of the sum of the mass of the shell material and the core material.
  • the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material 100 can be 8.9wt%, 8.5wt%, 8wt%, 7.5wt%, 7wt%, 6.5wt%, 6wt%, 5.5wt%, 5wt%, 4.5wt%, 4.2wt%, 4wt%, 3.5wt%, 3wt%, 2.5wt%, 2% or 1%, etc.
  • the mass proportion is 2.5wt%-8.6wt%.
  • the mass proportion is 3wt%-7wt%, for example, 3.3wt%-6.5wt%.
  • the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material 100 is greater than 91wt%; in some embodiments, the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material 100 is 91.4wt%-97.5wt%, specifically 93wt%-97wt%, 93.5wt%-96.7wt%, etc.
  • the molar ratio of the cobalt element (Co) to the nickel element (Ni) in the positive electrode material 100 is less than 1%. In some cases, the molar ratio of the cobalt element to the nickel element in the core 101 and the shell 102 is less than 1%. In this way, the content of the cobalt element in the overall positive electrode material 100 is low, and can even be 0, which effectively reduces the cost.
  • the low-cobalt ⁇ -phase nickel hydroxide material can also inhibit the oxygen evolution reaction of the core material during the charge and discharge process to a certain extent, without affecting the improvement of the coulomb efficiency.
  • the positive electrode material 100 can take into account the good electrochemical properties such as high tap density, high coulomb efficiency, and high specific capacity, while also taking into account the advantages of low cost.
  • the molar ratio of cobalt element to nickel element in the positive electrode material 100 is less than 0.01%, and the molar ratio of cobalt element to nickel element in the core 101 and the shell 102 is less than 0.01%.
  • the core 101 and the shell 102 do not contain cobalt element. That is, the positive electrode material 100 does not contain cobalt element. At this time, the manufacturing cost of the positive electrode material 100 is low, and based on the close stacking of the ⁇ -phase nickel hydroxide material on the surface of the core 101, its effect of inhibiting oxygen evolution in the core is not reduced.
  • the specific surface area S of the positive electrode material 100 is less than or equal to 30m2 /g.
  • the specific surface area S can be measured by a nitrogen adsorption method (also known as the "BET method").
  • BET method nitrogen adsorption method
  • the shell layer of the positive electrode material 100 of the embodiment of the present application is formed by the dense stacking of the ⁇ -phase nickel hydroxide material, and the specific surface area of the positive electrode material 100 will not be too high to significantly reduce the tap density.
  • the present application controls the mass proportion of the ⁇ -phase nickel hydroxide material to be relatively small, which can make the tap density of the positive electrode material 100 higher.
  • the specific surface area of the positive electrode material 100 is 0.5-30m 2 / g, for example, 1m 2 / g, 2m 2 / g, 5m 2 / g, 8m 2 / g, 10m 2 / g, 12m 2 / g, 15m 2 / g, 20m 2 / g, 25m 2 / g or 28m 2 / g, etc.
  • the specific surface area of the positive electrode material is more suitable, and can better take into account high tap density and high rate output capacity.
  • the specific surface area of the positive electrode material 100 is within this range, the smaller average pore size of the pores in the shell 102 also ensures that the porosity of the positive electrode material is high, which is conducive to the improvement of cycle performance.
  • the specific surface area of the positive electrode material 100 is 2-30m 2 / g or 5-25m 2 / g, etc.
  • the coverage rate of the ⁇ -phase nickel hydroxide material is greater than or equal to 90%, for example ⁇ 92%, ⁇ 95% or ⁇ 98%, etc.
  • This parameter can reflect that the ⁇ -phase nickel hydroxide material has a high degree of coating on the surface of the core and its distribution is relatively uniform, which greatly avoids the problem of uneven coating caused by conventional secondary deposition technology, and the shell layer has a good effect of inhibiting oxygen evolution in the core.
  • the area coated by the ⁇ -phase nickel hydroxide material is greater than or equal to 90% of the surface area of the core 101. That is, the coverage rate of the shell material on the surface of the core is ⁇ 90%. This is conducive to ensuring sufficient coverage of the shell material, greatly avoiding the problem of uneven coating caused by conventional secondary deposition technology, and the shell has a better effect of inhibiting oxygen evolution in the core. In some embodiments, the above coverage rate is ⁇ 95%, or even 100%.
  • the shell 102 has pores, and the pores are formed by the accumulation of multiple particles of ⁇ -phase nickel hydroxide material. It can also be said that the shell 102 has a porous structure.
  • the shell 102 can be specifically formed by the accumulation of a plurality of primary particles 1021 of ⁇ -phase nickel hydroxide material, and pores are formed between at least some of the primary particles 1021 of ⁇ -phase nickel hydroxide material, and the average pore size of the pores is 1nm-50nm.
  • the average pore size is much lower than the pore size in the loose coating layer obtained by the conventional coprecipitation method.
  • the smaller average pore size can also reflect the close packing of the above-mentioned ⁇ -phase nickel hydroxide material on the surface of the core 101 from the side, which is beneficial for the positive electrode material 100 to take into account both high tap density and high coulomb efficiency; at the same time, it is also beneficial to improve the porosity of the shell 102, thereby improving the porosity of the overall positive electrode material 100, which can better alleviate the stress change of the ⁇ -phase nickel hydroxide material during the charge and discharge cycle, thereby reducing the particle pulverization phenomenon of the positive electrode material 100, and is beneficial to the improvement of the battery cycle life.
  • the shell 102 of the present application is tightly packed/coated and porous, wherein the tight coating of the shell 102 can reduce the particle pulverization phenomenon of the core material during the cycle process and improve the cycle stability, and the presence of the porous structure in the shell can further facilitate the stress release of the core particles during the charge and discharge process, so that the positive electrode material 100 can take into account high tap density and high coulomb efficiency, high specific capacity, good rate performance, long cycle life, etc.
  • the average pore size of the above pores can be obtained by cross-sectional electron microscopy characterization of the positive electrode material 100, or by nitrogen adsorption method.
  • its pore size refers to the maximum lateral dimension of the pore, specifically the distance between the two points with the largest dimension on its cross section, which can be determined according to the specific shape of the cross section.
  • the pore size specifically refers to the diameter of the circle.
  • the pore size refers to the diameter of its circumscribed circle.
  • the average pore size of the pores can be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 22 nm, 25 nm, 30 nm, 35 nm, 40 nm or 45 nm, etc. In some embodiments, the average pore size of the pores is 5-50 nm.
  • the primary particles 1021 of the ⁇ -phase nickel hydroxide material are in the form of thin sheets, and their thickness is at the nanometer level, so they can be called "nano-sheets".
  • the thickness of the nanosheet can be 5-20nm.
  • the thinner sheet structure is more conducive to ensuring that the stacking degree of the primary particles 1021 of the ⁇ -phase nickel hydroxide material is more compact, and appropriately increases the specific area of the positive electrode material 100, which is conducive to the improvement of its ion transport and the wettability of the electrolyte to it, improves the kinetic characteristics, and improves its rate output capacity.
  • the porosity of the shell 102 may be 5-40%.
  • the porosity may be obtained by cross-sectional electron microscopy of the positive electrode material 100, or by nitrogen adsorption.
  • the porosity may be different at different positions of the shell 102, wherein the porosity of the shell 102 may be lower at a location closer to the core 101, and the stacking degree of the shell material may be higher.
  • the overall pore volume of the shell 102 is less than or equal to 0.2 cm 3 /g, for example, 0.18, 0.15, 0.12, 0.11, 0.1, 0.08, 0.05, 0.03 or 0.01 cm 3 /g. In some embodiments, the pore volume of the shell 102 may be 0.05-0.15 cm 3 /g.
  • the pore volume of the overall positive electrode material 100 (which can be measured by nitrogen adsorption method) can represent the pore volume of the shell 102.
  • the smaller pore volume of the shell 102 also reflects the close packing of the primary particles of the ⁇ -phase nickel hydroxide material on the surface of the core 101, which is conducive to making the positive electrode material have a higher tap density and better electrochemical performance.
  • the tap density of the positive electrode material 100 is greater than or equal to 1.8 g/cm 3 .
  • the tap density of the positive electrode material 100 is 1.9 g/cm 3 -2.4 g/cm 3 .
  • the ⁇ -phase nickel hydroxide material with low intrinsic density is introduced with a small mass proportion, which can ensure that the positive electrode material 100
  • the tap density is relatively high, and combined with the tight coating of the shell layer 102 of the present application, it is conducive to further improving the tap density, so that the loading amount of active materials in the electrode made of the positive electrode material 100 can be increased, the area specific capacity and volume specific capacity of the electrode can be increased, and the volume energy density of the battery can be increased.
  • the tap density of the positive electrode material is 2.0-2.4g/ cm3 , or even 2.1-2.4g/ cm3 , for example, 2.15, 2.2, 2.3, 2.4g/ cm3 .
  • the maximum dimension of the primary particle 1021 of the ⁇ -phase nickel hydroxide material along the radial direction of the positive electrode material 100 particle is smaller than the grain diameter of the ⁇ -phase nickel hydroxide material. That is, the positive electrode material 100 is a composite structure in which the grains are large inside and small outside, and the structural stability is better.
  • the primary particles 1021 of the ⁇ -phase nickel hydroxide material can be randomly grown and arranged on the surface of the core 101 (i.e., non-oriented and randomly grown and accumulated on the surface of the core 101.
  • the primary particles of the ⁇ -phase nickel hydroxide material grow radially along the radial direction of the positive electrode material 100 and accumulate on the surface of the core 101 to form a shell 102, that is, some of the primary particles of the ⁇ -phase nickel hydroxide material are arranged in an oriented growth, specifically in a radial radial arrangement.
  • This part of the primary particles of the ⁇ -phase nickel hydroxide material is usually located on the outer surface of the shell 102, which is more conducive to effectively releasing the stress accumulated in the positive electrode material 100 during the charge and discharge cycle, reducing the accumulation of internal stress, and extending the cycle life.
  • the distribution of the primary particles of the ⁇ -phase nickel hydroxide material on the core 101 is a combination of the aforementioned two methods.
  • the core 101 i.e., the ⁇ -phase nickel hydroxide material
  • the shell 102 is a polycrystalline structure.
  • the shell 102 is formed by stacking a plurality of primary particles 1021 of ⁇ -phase nickel hydroxide material, and the primary particles 1021 of the plurality of ⁇ -phase nickel hydroxide material grow on the surface of the core 101.
  • the positive electrode material 100 has the advantages of both a single crystal or quasi-single crystal structure and a polycrystalline structure, and can obtain good structural stability and good cycle performance.
  • the ⁇ -phase nickel hydroxide material is spherical or quasi-spherical.
  • the positive electrode material 100 is a spherical or quasi-spherical particle.
  • the core 101 After being coated, the core 101 still maintains its spherical or nearly spherical morphology, and the overall composite material also presents a morphology similar to that of the core 101, which is conducive to ensuring that the overall composite material has a higher tap density.
  • the particle diameter of the positive electrode material 100 is D
  • the thickness of the shell 102 is d
  • d and D are measured in the same unit, 0 ⁇ d ⁇ 0.08D.
  • D and d can be obtained through the electron microscope photo of the positive electrode material 100.
  • d ⁇ 0.08D which can reflect that the coating thickness of the shell 102 is thin, which is conducive to ensuring a tighter coating, and can avoid the problems of low tap density, unstable coating layer and easy falling off caused by the loose coating of a large amount of ⁇ -phase nickel hydroxide material.
  • D can be in the micron level
  • d can be in the nanometer level or submicron level.
  • D is in the range of 2 ⁇ m-25 ⁇ m, for example, 5 ⁇ m, 6 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 22 ⁇ m or 24 ⁇ m, etc. In some embodiments, D is in the range of 15 ⁇ m-25 ⁇ m. In the embodiment of the present application, d can be in the range of 10nm-800nm, and further in the range of 15nm-600nm. In some embodiments, d may be in the range of 15-420 nm, such as 20-420 nm, 20-250 nm, 20-210 nm, or 15-220 nm, or 15-180 nm, etc. In some embodiments, d may be in the range of 25-580 nm.
  • the average secondary particle size D2 of the positive electrode material 100 is 5 ⁇ m-15 ⁇ m.
  • the average secondary particle size D2 is the average particle size of the positive electrode material particles in its dispersion measured based on the dynamic light scattering method (Dynamic Light Scattering, DLS method).
  • D2 can be 8 ⁇ m-12 ⁇ m. Suitable D2 can adjust the transport channels of electrons, ions, etc. of the positive electrode material 100 during the electrochemical reaction process, ensure its high electrochemical activity, and achieve its high specific capacity and high rate performance.
  • the ⁇ -phase nickel hydroxide material is in-situ accumulated and grown on the surface of the inner core 101.
  • the ⁇ -phase nickel hydroxide material can be obtained by an in-situ phase transformation reaction of the inner core raw material- ⁇ -phase nickel hydroxide raw material.
  • the generated ⁇ -phase nickel hydroxide material has a higher compactness on the inner core surface, which is more conducive to the improvement of the tap density of the composite material.
  • the ⁇ -phase nickel hydroxide material can be specifically obtained by an ion penetration self-exchange reaction of a ⁇ -phase nickel hydroxide raw material with a metal soluble salt and an anion soluble salt.
  • the metal element in the metal soluble salt can replace the metal cation in the ⁇ -phase nickel hydroxide raw material.
  • the ⁇ -phase nickel hydroxide material contains a first non-nickel metal element M, and M includes one or more of aluminum (Al), iron (Fe), manganese (Mn), yttrium (Y) or ytterbium (Yb).
  • the introduction of the above-mentioned M element into the ⁇ -phase nickel hydroxide material of the present application is conducive to ensuring the good structural stability of the ⁇ -phase material, inhibiting its transformation back to the ⁇ -phase during the charge and discharge cycle, and improving the cycle stability of the positive electrode material; at the same time, the above-mentioned M element is a metal element that can replace the metal cations (including Ni 2+ , etc.) in the ⁇ -phase nickel hydroxide material, which can ensure that the ⁇ -phase nickel hydroxide material can be successfully generated through the in-situ reaction, and the in-situ coating of the ⁇ -phase nickel hydroxide material can be achieved, and as mentioned above, the M element enters the bulk phase of the ⁇ -phase nickel hydroxide material to further inhibit its oxygen evolution side reaction.
  • the ⁇ -phase nickel hydroxide material contains anions Q, and the anions Q include one or more of CO 3 2- (carbonate), SO 4 2- (sulfate), NO 3 - (nitrate), Cl - (chloride), and Br - (bromide). These anions Q can be intercalated into the interlayer of nickel hydroxide to further improve the chemical stability of the ⁇ -phase nickel hydroxide and improve the cycle life of the positive electrode material.
  • the anion Q includes at least CO 3 2- .
  • the anion CO 3 2- is more conducive to increasing the interlayer distance of the ⁇ -phase nickel hydroxide, improving its structural stability and ionic conductivity.
  • the chemical formula of the ⁇ -phase nickel hydroxide material may include Ni 1-y M y (OH) 2-z Q z ⁇ nH 2 O, wherein: 0 ⁇ y ⁇ 0.3, 0 ⁇ z ⁇ 0.1, 0 ⁇ n ⁇ 1; M includes one or more of Al, Fe, Mn, Y, and Yb; Q includes one or more of CO 3 2- , SO 4 2- , NO 3 - , Cl - , and Br - . In some embodiments, M does not include Co.
  • the ⁇ -phase nickel hydroxide material contains a second non-nickel metal element A, and the A element includes one or more of zinc (Zn), magnesium (Mg), calcium (Ca), barium (Ba), aluminum (Al), iron (Fe), manganese (Mn), yttrium (Y) or ytterbium (Yb).
  • the A element helps to improve its oxygen evolution overpotential, thereby improving the coulombic efficiency of the positive electrode material and improving the comprehensive electrochemical performance.
  • the chemical formula of the above-mentioned ⁇ -phase nickel hydroxide material may include Ni 1-x A x (OH) 2 , 0 ⁇ x ⁇ 0.15, and A includes one or more of Zn, Mg, Ca, Ba, Al, Fe, Mn, Y or Yb. Further, A may not be a Co element. In some embodiments, A includes at least one of Al, Fe, Mn, Y, and Yb.
  • the shell layer may be an ⁇ -phase nickel hydroxide material with a certain change in composition.
  • the chemical formula of the shell layer material may still satisfy Ni 1-y M y (OH) 2-z Q z ⁇ nH 2 O, but at different positions of the shell layer, the subscript value and n value of each element in the chemical formula may be different.
  • the content of each M element on the side close to the core 101 is less than its content on the surface of the shell layer.
  • the positive electrode material 100 can be prepared by the ion permeation self-exchange reaction described below in the present application, and its shell layer 102 is denser.
  • the content gradient of each M element in the shell layer 102 decreases from the shell layer 102 to the core 101.
  • the M element source gradually penetrates into the ⁇ -phase nickel hydroxide material, ensuring that the stacking density of the shell material- ⁇ -phase nickel hydroxide material is higher.
  • the "gradient reduction” can be specifically “gradually reduced”.
  • the content of Ni element near the shell 102 side is less than the content of Ni element at the core of the kernel 101. This can also be reflected in the side that when the positive electrode material 100 is prepared by ion permeation self-exchange reaction, the shell 102 is obtained by replacing the Ni element in the ⁇ -phase nickel hydroxide raw material at a certain depth in situ, and the resulting shell 102 is denser.
  • the content of Ni (nickel) element in the kernel 101 increases in a gradient, that is, the value of 1-x increases in a gradient.
  • the "gradient increase" can be gradually increased and then remain unchanged (such as, when approaching a certain distance from the kernel core, the value of 1-x basically no longer changes).
  • the Ni element content in the ⁇ -phase nickel hydroxide material is greater than the Ni element content in the ⁇ -phase nickel hydroxide material. In this way, from the shell 102 to the direction of the kernel 101, the content of Ni element is all increased in a gradient.
  • the content of the A element increases gradually from the core 101 to the shell 102.
  • the positive electrode material 100 is prepared by ion permeation self-exchange reaction, the content of the Ni element in the ⁇ -phase nickel hydroxide material is greater than the content of the Ni element in the ⁇ -phase nickel hydroxide material, that is, 1-x is greater than 1-y, and accordingly, x ⁇ y, so for a single particle of the positive electrode material, the aforementioned same element tends to increase gradually from the inside to the outside.
  • a and M are the same element, it still satisfies "from the shell 102 to the core 101, the content gradient of the M element in the shell 102 decreases, and the content gradient of the Ni element in the core 101 increases".
  • the positive electrode material 100 further includes a transition layer between the core 101 and the shell 102, wherein the transition layer includes the material of the core 101 and the material of the shell 102, that is, the ⁇ -phase nickel hydroxide material and the ⁇ -phase nickel hydroxide material.
  • the transition layer includes the material of the core 101 and the material of the shell 102, that is, the ⁇ -phase nickel hydroxide material and the ⁇ -phase nickel hydroxide material.
  • the transition layer at least some of the bulk phase of the ⁇ -phase nickel hydroxide material is filled with the ⁇ -phase nickel hydroxide material.
  • at least some of the ⁇ -phase nickel hydroxide material can enter the bulk phase of the ⁇ -phase nickel hydroxide material. This helps to further suppress the oxygen evolution side reaction of the ⁇ -phase nickel hydroxide material during the anodic oxidation process.
  • the present invention also provides a method for preparing the positive electrode material, comprising the following steps:
  • a ⁇ -phase nickel hydroxide raw material is mixed with a reaction solution containing a soluble salt of a first non-nickel metal element M and a soluble salt of an anion Q, and a positive electrode material is obtained through an ion permeation self-exchange reaction; wherein the positive electrode material comprises a core and a shell coated on the surface of the core, the core comprises a ⁇ -phase nickel hydroxide material, the shell comprises an ⁇ -phase nickel hydroxide material, at least some particles of the ⁇ -phase nickel hydroxide material have pores, and the average pore size of the pores is 1-50nm; the mass proportion of the ⁇ -phase nickel hydroxide material in the positive electrode material is less than 9wt%; wherein M comprises one or more of Al, Fe, Mn, Y, and Yb, and Q comprises one or more of CO 3 2- , SO 4 2- , NO 3 - , Cl - , and Br - .
  • the ⁇ -phase nickel hydroxide raw material and the soluble salt of the metal element M and the soluble salt of the anion Q can undergo an in-situ ion permeation self-exchange reaction at a certain temperature, and the in-situ generation of the ⁇ -phase nickel hydroxide material can be achieved by means of the substitution/doping of the metal ions (at least including nickel ions) in the ⁇ -phase nickel hydroxide raw material by the M ions and the intercalation of the anions Q, and the in-situ coating of the ⁇ -phase nickel hydroxide material after the reaction by the ⁇ -phase material.
  • the ⁇ -phase nickel hydroxide material can be more closely stacked on the surface of the ⁇ -phase material, and its distribution on the surface of the inner core is relatively uniform, which can avoid the problems of uneven coating and non-compact and easy-to-fall-off of the coating layer material caused by the traditional secondary precipitation technology.
  • the shell material can play a synergistic role with the inner core material, and cooperate with the lower mass proportion of the shell material, so that the positive electrode material can take into account high tap density, high coulomb efficiency, high specific capacity, good rate performance, etc.
  • the above preparation method may not introduce any Co-containing material, which may help reduce the preparation cost of the positive electrode material.
  • the chemical formula of the ⁇ -phase nickel hydroxide raw material is Ni 1-x' A' x' (OH) 2 , wherein 0 ⁇ x' ⁇ 0.15, A' is a non-nickel metal element, and A' includes one or more of Zn, Mg, Ca, Ba, Al, Fe, Mn, Y or Yb.
  • A' is a non-nickel metal element
  • A' includes one or more of Zn, Mg, Ca, Ba, Al, Fe, Mn, Y or Yb.
  • the ⁇ -phase nickel hydroxide raw material may contain the A' element, or may not contain the A' element. When the A' element is contained, it helps to increase the oxygen evolution overpotential of the ⁇ -phase nickel hydroxide material in the positive electrode material, thereby improving the coulombic efficiency of the positive electrode material.
  • A' may include one or more of Zn, Mg, Ca, and Ba.
  • A' may not be Co, and further, A' may be at least one of Zn,
  • the soluble salt of the metal element M and the soluble salt of the anion Q can effectively ensure the smooth occurrence of the ion penetration self-exchange reaction, and efficiently construct the ⁇ -phase nickel hydroxide coating layer with stable structure.
  • the metal cation of the above-mentioned M element can replace the metal cation (such as Ni ion, A' ion) in the ⁇ -phase nickel hydroxide raw material, ensure the smooth occurrence of the in-situ coating reaction, so that the surface of the ⁇ -phase nickel hydroxide is successfully transformed into the ⁇ -phase nickel hydroxide, and the M ion can make the chemical stability of the formed ⁇ -phase nickel hydroxide material higher, and the cycle stability of the positive electrode material is good.
  • anions such as CO 3 2- (carbonate ) , SO 4 2- (sulfate), NO 3- (nitrate), Cl- (chloride ion), Br- (bromide ion) can be intercalated to the interlayer of nickel hydroxide, further improve the chemical stability of the ⁇ -phase nickel hydroxide material, and enhance the cycle life of the positive electrode material.
  • the presence of these anions is not easy to cause the above-mentioned M ions to settle in the reaction solution.
  • Q at least includes CO 3 2- .
  • the anion CO 3 2- is more conducive to the smooth generation of the ⁇ -phase nickel hydroxide, and improves its structural stability and ion conductivity, thereby improving the rate performance and cycle performance of the obtained positive electrode material.
  • soluble salt in this application specifically refers to a salt that is soluble in water.
  • the soluble salt of the metal element M may specifically include one or more of sulfate, nitrate or chloride of M.
  • the soluble salt of the anion Q may include one or more of sodium salt, potassium salt, lithium salt, ammonium salt, etc. containing the anion Q.
  • the sources of the soluble salt of the metal element M and the soluble salt of the anion Q are abundant and cheap, which is conducive to reducing the manufacturing cost. Among them, regulating the types of M and Q can simplify the solutes in the above-mentioned reaction solution, and further reduce the manufacturing cost while ensuring that the ion permeation self-exchange reaction occurs smoothly and the comprehensive performance of the obtained positive electrode material is good.
  • the soluble salt of the metal element M is a nitrate
  • the anion Q is CO 3 2- .
  • the concentration of the soluble salt of the metal element M does not exceed 3.0 mol/L; the concentration of the soluble salt of the anion Q does not exceed 3.0 mol/L.
  • the ratio of the mass of the ⁇ -phase nickel hydroxide raw material to the volume of the reaction solution i.e., the solid-liquid ratio
  • the coating thickness and coating compactness of the shell layer in the positive electrode material can be regulated, as well as the preparation efficiency of the above-mentioned positive electrode material can be improved and the production cost can be reduced.
  • the above-mentioned solid-liquid ratio can specifically be 1: 5kg/L, 1: 10kg/L, 1: 20kg/L, 1: 25kg/L, 1: 30kg/L, 1: 40kg/L, 1: 50kg/L, 1: 60kg/L, 1: 70kg/L, 1: 80kg/L, 1: 90kg/L, etc.
  • the solid-liquid ratio is 1: (20-60) kg/L.
  • the temperature of the ion permeation self-exchange reaction can be 50°C-120°C, and the reaction time is 1-24 hours.
  • the coating thickness, coating compactness, micromorphology of the shell, etc. of the ⁇ -phase nickel hydroxide material can be controlled.
  • the reaction temperature can be 60°C, 70°C, 80°C, 85°C, 90°C, 100°C, 110°C, 115°C or 120°C, etc.
  • the temperature of the ion permeation self-exchange reaction is 85-120°C.
  • reaction time is 1-10 hours, for example, 2h, 3h, 4h, 5h, 6h, 8h, 10h, etc.
  • the chemical formula of the ⁇ -phase nickel hydroxide material includes Ni 1-y M y (OH) 2-z Q z ⁇ nH 2 O, wherein 0 ⁇ y ⁇ 0.3, 0 ⁇ z ⁇ 0.1, 0 ⁇ n ⁇ 1, and the y gradient in the shell decreases from the shell to the core.
  • the chemical formula of the ⁇ -phase nickel hydroxide material includes Ni 1-x A x (OH) 2 , wherein 0 ⁇ x ⁇ 0.15, A includes the above-mentioned A', and the 1-x gradient in the inner core increases to the above-mentioned 1-x' from the shell to the inner core. It can be understood that at the inner core of the positive electrode material, 1-x is equal to 1-x', and the chemical formula of the ⁇ -phase nickel hydroxide material is the same as the above-mentioned ⁇ -phase nickel hydroxide raw material.
  • A includes A' and M. That is, the inner core is infiltrated with the M element derived from the shell material.
  • the doping of specific M ions and the intercalation of anions Q can be achieved by ion self-exchange at a certain temperature, so that a certain thickness of the surface layer of the ⁇ -phase nickel hydroxide is converted into an ⁇ -phase material and its coating is achieved.
  • the preparation method is simple and easy to operate, the reaction parameters are easy to control, and it is easy to achieve uniform and tight coating of the ⁇ -phase nickel hydroxide material, which can get rid of the problems of uneven coating and the coating layer being not compact, easy to fall off, and poor electrochemical performance of the positive electrode material caused by the use of traditional secondary precipitation technology.
  • the reaction parameters are easy to control, and it is easy to achieve uniform and tight coating of the ⁇ -phase nickel hydroxide material, which can get rid of the problems of uneven coating and the coating layer being not compact, easy to fall off, and poor electrochemical performance of the positive electrode material caused by the use of traditional secondary precipitation technology.
  • ion penetration self-exchange reaction due to the Kirkendall effect, a rich porous structure will be formed in the shell.
  • the specific microstructural parameters of the porous structure can be found in the description of the previous text of this application.
  • the embodiments of the present application also provide a positive electrode plate for an alkaline storage battery, wherein the positive electrode plate comprises the positive electrode material described above in the embodiments of the present application, or comprises a positive electrode material prepared by the method for preparing the positive electrode material described above in the embodiments of the present application.
  • the positive electrode sheet 200 provided in the embodiment of the present application includes a positive electrode current collector 201 and a positive electrode material layer 202 disposed on the positive electrode current collector 201, wherein the positive electrode material layer 202 includes a positive electrode active material 2021, and the positive electrode active material 2021 includes the above-mentioned positive electrode material 100 described in the embodiment of the present application.
  • a positive electrode material layer 202 is disposed on one side surface or on two opposite sides of the positive electrode current collector 201.
  • the positive electrode current collector 201 may be a conventional choice in the battery field, for example, it may be nickel foam, porous nickel foil, nickel-plated perforated steel belt, perforated steel belt, etc.
  • the positive electrode material layer 202 may also include a binder, a conductive agent, etc.
  • the positive electrode active material 2021 may also include other positive active components.
  • the embodiment of the present application also provides an alkaline storage battery, which may include the positive electrode plate provided in the embodiment of the present application.
  • the alkaline storage battery 300 provided in the embodiment of the present application includes a positive electrode 31, a negative electrode 32, an electrolyte 33 and a diaphragm 34, as well as corresponding connecting accessories and circuits.
  • the diaphragm 34 is located between the positive electrode 31 and the negative electrode 32, and the positive electrode 31, the negative electrode 32 and the diaphragm 34 are immersed in the electrolyte 33.
  • the positive electrode 31 includes the positive electrode sheet 200 provided in the embodiment of the present application, that is, it also includes the positive electrode material 100 provided in the embodiment of the present application.
  • alkaline storage battery refers to a battery system based on nickel hydroxide positive electrode material, alkaline aqueous electrolyte and different negative electrodes.
  • alkaline storage batteries can be divided into different types, for example, the alkaline storage battery can be specifically a nickel-metal hydride battery, a nickel-zinc battery, a nickel-iron battery or a nickel-cadmium battery.
  • the negative electrode of the alkaline storage battery is a metal hydride negative electrode, a zinc negative electrode, an iron negative electrode or a cadmium negative electrode.
  • the negative electrode includes a negative electrode active material containing a Zn element, such as ZnO, etc.
  • the electrolyte of the alkaline storage battery can contain an alkaline electrolyte and water, and the alkaline electrolyte can include one or more of sodium hydroxide, potassium hydroxide, and lithium hydroxide.
  • the concentration of the alkaline electrolyte in the electrolyte can be 0.5-10mol/L.
  • the positive electrode is oxidized from nickel hydroxide material to nickel oxyhydroxide (for convenience, Ni(OH) 2 simply represents the positive electrode material of this application, and NiOOH represents its oxidation product), and the negative electrode is transformed from zinc oxide to metallic zinc.
  • the positive electrode loses electrons, and the electrons flow to the negative electrode through the external circuit, and electrical energy is stored; the discharge process is the opposite of charging, and the positive electrode is transformed from nickel oxyhydroxide back to nickel hydroxide, and at the same time, electrons migrate from the negative electrode to the positive electrode through the external circuit, releasing electrical energy to the outside.
  • the specific reaction formula is as follows:
  • the embodiment of the present application also provides an electronic device, which may include a charging circuit and an alkaline storage battery 300 as provided in the embodiment of the present application.
  • the alkaline storage battery 300 may be electrically connected to the charging circuit, so that it is convenient for it to power the electronic device.
  • the electronic device may include various consumer electronic products, such as mobile phones, tablet computers, laptops, mobile power supplies, and other wearable or portable electronic devices, such as smart bracelets, smart TVs, home office equipment, and may also be electronic products such as automobiles and energy storage devices.
  • consumer electronic products such as mobile phones, tablet computers, laptops, mobile power supplies, and other wearable or portable electronic devices, such as smart bracelets, smart TVs, home office equipment, and may also be electronic products such as automobiles and energy storage devices.
  • the electronic device 400 of the embodiment of the present application may be various movable devices for loading, transportation, assembly, disassembly, security, etc., for example, various forms of vehicles.
  • the electronic device 400 in FIG. 5 may include a vehicle body 401, a mobile component 402 (such as a wheel), and a drive component, the drive component includes a motor 403 and a battery system 404, and the battery system 404 includes the above-mentioned alkaline storage battery 300 provided in the embodiment of the present application.
  • the battery system 404 may be electrically connected to the motor 403, which may supply power to the motor 403, and the motor 403 provides power to drive the mobile component 402 of the electronic device 400 to move.
  • the battery system 404 may include a battery pack composed of a plurality of the above-mentioned alkaline storage batteries 300.
  • an embodiment of the present application further provides an energy storage system 500 , which may include a battery pack 501 and a battery management system 502 electrically connected to the battery pack 501 , wherein the battery pack 501 includes the alkaline storage battery 300 provided in the embodiment of the present application.
  • a preparation method of a positive electrode material comprising:
  • alkaline nickel-zinc half-cell The positive electrode material prepared in Example 1, the binder-polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were added to N-methylpyrrolidone (NMP) at a mass ratio of 90:5:5, and the mixture was stirred and mixed to obtain a slurry. The slurry was coated on nickel foam and dried in an oven at 80°C for 2 hours to obtain a positive electrode sheet. A 6 mol/L KOH aqueous solution saturated with ZnO was used as the electrolyte, and zinc metal was used as the counter electrode of the above-mentioned positive electrode sheet, and an alkaline nickel-zinc half-cell was assembled in an air atmosphere.
  • NMP N-methylpyrrolidone
  • the chemical formula of the ⁇ -phase material at the core of the inner core is Ni 0.95 Zn 0.05 (OH) 2
  • the chemical formula of the ⁇ -phase nickel hydroxide material on the outer surface of the shell is Ni 0.82 Al 0.18 (OH) 1.92 (CO 3 ) 0.08 ⁇ 0.75H 2 O, wherein the content of the Al element in the shell decreases from the shell to the inner core, and the content of the Ni element in the inner core increases.
  • the distribution range of the particle diameter D of the positive electrode material of Example 1 is 2 to 22 ⁇ m, the thickness d of the shell layer is about 20 to 250 nm, and the average secondary particle size of the positive electrode material is 10.5 ⁇ m, wherein the mass proportion of the shell material— ⁇ -phase nickel hydroxide material in the positive electrode material is about 4.2%.
  • a preparation of a positive electrode material which is different from Example 1 in that the reaction time of step (2) is extended to 6 hours.
  • the positive electrode material of Example 2 is used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material prepared in Example 2 is 2 to 22 ⁇ m
  • the thickness d of the shell layer is about 50 to 760 nm
  • the average secondary particle size of the positive electrode material is 10.9 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 8.6%.
  • a preparation method for a positive electrode material which is different from that of Example 1 in that: in step (2), the mass of the cobalt-free spherical ⁇ -phase Ni 0.95 Zn 0.05 (OH) 2 raw material is 2 g.
  • Example 3 the positive electrode material of Example 3 was used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material prepared in Example 3 is 2 to 22 ⁇ m, the thickness d of the shell layer is about 15 to 180 nm, and the average secondary particle size of the positive electrode material is 10.5 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 2.5%.
  • a preparation of a positive electrode material which is different from Example 1 in that the ⁇ -phase nickel hydroxide raw material used is a ⁇ -phase cobalt-free spherical Ni 0.93 Zn 0.07 (OH) 2 positive electrode material.
  • the positive electrode material of Example 4 was used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material prepared in Example 4 is 2 to 25 ⁇ m
  • the thickness d of the shell layer is about 15 to 220 nm
  • the average secondary particle size of the positive electrode material is 11.4 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 3.5%.
  • a preparation of a positive electrode material which is different from Example 1 in that: in step (2), after the reaction kettle is sealed, it is placed in an oven at 80° C. for reaction for 6 hours.
  • the positive electrode material of Example 5 was used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material obtained in Example 5 is 2 to 22 ⁇ m
  • the thickness d of the shell layer is about 25 to 580 nm
  • the average secondary particle size of the positive electrode material is 10.7 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 6.5%.
  • a preparation method of a positive electrode material comprising:
  • the positive electrode material of Example 6 is used to prepare a positive electrode plate, and an alkaline nickel-zinc half-cell is assembled.
  • the distribution range of the particle diameter D of the positive electrode material obtained in Example 6 is 2 to 22 ⁇ m, the thickness of the shell is about 20 to 210 nm, and the average secondary particle size of the positive electrode material is 10.5 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 3.4%.
  • a preparation of a positive electrode material which is different from Example 1 in that the ⁇ -phase nickel hydroxide raw material used is a ⁇ -phase cobalt-free spherical Ni 0.95 Mg 0.05 (OH) 2 positive electrode material.
  • Example 7 the positive electrode material of Example 7 was used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material obtained in Example 7 is 2 to 28 ⁇ m, the thickness d of the shell layer is about 15 to 220 nm, and the average secondary particle size of the positive electrode material is 10.8 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 3.8%.
  • a preparation of a positive electrode material which is different from Example 1 in that the ⁇ -phase nickel hydroxide raw material used is a ⁇ -phase cobalt-free spherical Ni 0.97 Al 0.03 (OH) 2 positive electrode material.
  • Example 8 According to the method described in Example 1, the positive electrode material of Example 8 was used to prepare a positive electrode sheet and an alkaline nickel-zinc half-cell.
  • the distribution range of the particle diameter D of the positive electrode material obtained in Example 8 is 2 to 25 ⁇ m
  • the thickness d of the shell layer is about 15 to 320 nm
  • the average secondary particle size of the positive electrode material is 11.6 ⁇ m.
  • the mass proportion of the shell material - ⁇ -phase nickel hydroxide material in the positive electrode material is about 4.8%.
  • Uncoated ⁇ -phase cobalt-free Ni 0.95 Zn 0.05 (OH) 2 was directly used as the positive electrode material, and was prepared into a positive electrode sheet and an alkaline nickel-zinc half-cell using the method described in Example 1.
  • the ⁇ -phase cobalt-free Ni 0.8 Al 0.2 (OH) 2 material was prepared by coprecipitation method.
  • the specific preparation steps are as follows:
  • step (1) and step (2) under magnetic stirring, the solutions in step (1) and step (2) were added to the reactor in parallel, the reaction pH was controlled to be 11-11.5, and the reaction was carried out at 60° C. for 6 h;
  • reaction material is filtered, and the solid matter is washed and dried to obtain a pure ⁇ -phase nickel hydroxide positive electrode material.
  • Example 1 According to the method described in Example 1, the ⁇ -phase cobalt-free nickel hydroxide material of Comparative Example 2 was used to prepare the positive electrode plate, and the alkaline nickel-zinc half-cell was assembled.
  • the positive electrode material of ⁇ -phase nickel hydroxide coated with ⁇ - phase nickel hydroxide is prepared by coating ⁇ -phase nickel hydroxide with ⁇ -phase nickel hydroxide in a coprecipitation + hydrothermal manner, and the mass proportion of ⁇ -phase nickel hydroxide in the positive electrode material is greater than 10wt%.
  • the preparation of the positive electrode material specifically includes the following steps:
  • the positive electrode material of Comparative Example 3 was used to prepare a positive electrode sheet, and an alkaline nickel-zinc half-cell was assembled.
  • the positive electrode material of Comparative Example 4 was used to prepare a positive electrode sheet, and the positive electrode sheet was assembled into an alkaline nickel-zinc half-cell.
  • the positive electrode material prepared in Comparative Example 1 is not a core-shell type, and the ⁇ -phase nickel hydroxide material and the ⁇ -phase nickel hydroxide material are in a mutually dispersed state.
  • Figure 6 summarizes the X-ray diffraction patterns of the uncoated ⁇ -phase cobalt-free spherical nickel hydroxide material (Comparative Example 1) and the positive electrode material of the ⁇ -phase cobalt-free nickel hydroxide material coated with the ⁇ -phase cobalt-free nickel hydroxide prepared in Example 1. It can be seen from Figure 6 that the crystallization properties of the original ⁇ -phase nickel hydroxide are not changed after the in-situ coating reaction, and new ⁇ -phase nickel hydroxide is generated after the coating reaction. Through X-ray diffraction refinement fitting, it is known that the mass proportion of the generated ⁇ -phase nickel hydroxide in the positive electrode material is about 4.2%.
  • Figures 7 and 8 are SEM morphology images of an uncoated ⁇ -phase nickel hydroxide material and a material coated by the method of Example 1, respectively.
  • the right image in each figure is an enlarged view of a portion of the left image. From the comparison of Figures 7 and 8, it can be seen that the coated positive electrode material prepared by the method of Example 1 still maintains the spherical morphology of the core raw material, which is conducive to ensuring a higher tap density of the positive electrode material, wherein the tap density of the powder measured by the tap density is greater than 1.8 g/cm 3.
  • the surface of the ⁇ -phase nickel hydroxide material is a spindle-shaped structure of stacked nanocrystals.
  • the surface of the positive electrode material is transformed into a tightly stacked structure of nanosheets, and has a rich porous structure, which is conducive to increasing the specific surface area of the material, improving the kinetic properties and electrochemical activity of the material, and thus improving the rate output capacity of the material.
  • the cross-sectional SEM and EDS (Energy Dispersive Spectroscopy) element distribution diagram of the positive electrode material in Figure 9 it can be seen that during the coating reaction, the Al element of the shell can penetrate into the bulk phase of the core ⁇ -phase nickel hydroxide to achieve cation doping of the ⁇ -phase, which can help inhibit the oxygen evolution reaction of the ⁇ -phase.
  • FIG10 is a comparison of cyclic voltammetry curves of nickel-zinc half-cells prepared using the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 and the coated positive electrode material of Example 1.
  • the uncoated ⁇ -phase nickel hydroxide material of Comparative Example 1 undergoes a competition between the anodic oxidation reaction and the oxygen evolution side reaction in the high voltage range, and particularly at high scan rates (such as 1 mV ⁇ s -1 ), no complete anodic oxidation peak is observed, indicating that the anodic oxidation process of the positive electrode active material is insufficient.
  • the anodic oxidation peak (upward convex part) of the positive electrode material obtained after coating is clearly visible, and the boundary between it and the oxygen evolution side reaction (the upward part behind the anodic oxidation peak) is clear, which indicates that the tight coating of the ⁇ -phase cobalt-free nickel hydroxide material significantly inhibits the oxygen evolution side reaction during the anodic oxidation process, so that the anodic oxidation process of the positive electrode material can be fully carried out; at the same time, compared with the material of Comparative Example 1, the anodic oxidation peak of the positive electrode material in Example 1 of the present application shifts to the left as a whole, and with the increase of the scanning rate, its anodic peak shifts to the right and the cathode peak (the concave part) shifts to the left, and the voltage difference between the two becomes smaller, indicating that the degree of polarization of the positive electrode material is small, the reversibility and kinetic characteristics of the electrode are improved, and better rate performance can be achieved.
  • FIG. 11 is a comparison diagram of the charge and discharge curves of the nickel-zinc half-cell of Example 1 and Comparative Example 1. It can be seen from FIG. 11 that the potential difference in the middle of the charge and discharge curve of the half-cell of Example 1 (about 135 mV) is less than the potential difference in the middle of the charge and discharge curve of the half-cell of Comparative Example 1 (about 163 mV), which also shows that the ⁇ -phase nickel hydroxide material is tightly coated with the ⁇ -phase cobalt-free nickel hydroxide material, which helps to reduce the electrode polarization in the charge and discharge process.
  • the difference between the late charging and the median potential can be used to judge the oxygen evolution overpotential, wherein the 161 mV after coating is greater than the untreated 127 mV, indicating that it has an effect of inhibiting oxygen evolution.
  • the coulombic efficiency of the nickel-zinc half-cell prepared using the positive electrode material of Example 1 is as high as 94.1%, which is much higher than 84.4% of the battery prepared using the uncoated ⁇ -phase nickel hydroxide of Comparative Example 1, and the discharge specific capacity of the coated nickel positive electrode can be as high as 270 mAh/g, which is much higher than 244 mAh/g of the uncoated ⁇ -phase nickel hydroxide.
  • the nickel-zinc half-cell prepared using the positive electrode material of Example 1 has excellent rate discharge performance, and its discharge specific capacity at 20C is still as high as 259 mAh/g.
  • Table 1 summarizes the tap density of the samples of each embodiment and comparative example 1, as well as the relevant electrochemical properties of the prepared nickel-zinc half-cell.
  • the voltage range of each electrochemical image test is 1.3V-2V, and the 20C/2C ratio in Table 1 refers to the ratio of the discharge specific capacity at 20C to the maximum discharge specific capacity at 2C.
  • the ⁇ -phase nickel hydroxide coated ⁇ -phase nickel hydroxide can simultaneously give the obtained positive electrode material a higher specific capacity, higher coulomb efficiency, good rate performance and good cycle performance, and the comprehensive electrochemical performance is better, and the tap density of the positive electrode material is not too low.
  • the coating of more than 10% of the ⁇ -phase nickel hydroxide will significantly increase the tap density of the material, which is not conducive to obtaining a nickel-based battery with a high volume energy density.
  • the coulomb efficiency of the positive electrode material obtained by the secondary precipitation coating is low, and the oxygen evolution effect is not obvious.
  • the discharge specific capacity of the positive electrode material is far lower than that of the ⁇ -phase nickel hydroxide, which accounts for no more than 10% of the present embodiment (such as Example 2), which also reflects from the side that the shell ⁇ -phase nickel hydroxide and the core ⁇ -phase nickel hydroxide in the positive electrode material provided by the present application can play a synergistic role, and the positive electrode material can play a high specific capacity.
  • the coulombic efficiency of comparative example 4 which is a composite material obtained by direct mechanical mixing of ⁇ -phase nickel hydroxide and ⁇ -phase nickel hydroxide, is very low, almost equivalent to that of pure ⁇ -phase nickel hydroxide, which indicates that mechanical mixing cannot effectively inhibit oxygen evolution.

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Abstract

Des modes de réalisation de la présente demande concernent un matériau d'électrode positive, son procédé de préparation et son utilisation. Le matériau d'électrode positive comprend un noyau et une enveloppe revêtue sur la surface du noyau; le noyau comprend des matériaux d'hydroxyde de nickel à phase β; l'enveloppe comprend des matériaux d'hydroxyde de nickel à phase α; des pores existent entre des particules d'au moins certains des matériaux d'hydroxyde de nickel à phase α; l'ouverture moyenne des pores est de 1 à 50 nm; et le rapport massique des matériaux d'hydroxyde de nickel à phase α dans le matériau d'électrode positive est inférieur à 9 % en poids. Le matériau d'électrode positive peut présenter de bonnes propriétés électrochimiques telles qu'une densité après tassement élevée, un rendement en quantité élevé et une capacité spécifique élevée.
PCT/CN2023/135336 2022-11-30 2023-11-30 Matériau d'électrode positive, son procédé de préparation et son utilisation WO2024114720A1 (fr)

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JPH0982319A (ja) * 1995-09-08 1997-03-28 Sanyo Electric Co Ltd アルカリ蓄電池用正極活物質及びその製造方法
US5700596A (en) * 1991-07-08 1997-12-23 Matsushita Electric Industrial Co., Ltd. Nickel hydroxide active material powder and nickel positive electrode and alkali storage battery using them
CN1884101A (zh) * 2006-06-09 2006-12-27 厦门大学 核壳复合相结构氢氧化镍及其制备方法与应用
CN103112906A (zh) * 2013-03-12 2013-05-22 无锡市顺业科技有限公司 一种a相纳米纤维状氢氧化镍的合成方法
CN104466123A (zh) * 2014-12-27 2015-03-25 桂林理工大学 一种包覆β氢氧化镍的铝取代α氢氧化镍的制备方法
CN108475780A (zh) * 2016-01-05 2018-08-31 巴斯夫公司 用于碱性充电电池的氢氧化镍复合材料
CN109574090A (zh) * 2017-09-28 2019-04-05 比亚迪股份有限公司 氢氧化镍钴锰和正极材料及其制备方法和锂离子电池

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5700596A (en) * 1991-07-08 1997-12-23 Matsushita Electric Industrial Co., Ltd. Nickel hydroxide active material powder and nickel positive electrode and alkali storage battery using them
JPH0982319A (ja) * 1995-09-08 1997-03-28 Sanyo Electric Co Ltd アルカリ蓄電池用正極活物質及びその製造方法
CN1884101A (zh) * 2006-06-09 2006-12-27 厦门大学 核壳复合相结构氢氧化镍及其制备方法与应用
CN103112906A (zh) * 2013-03-12 2013-05-22 无锡市顺业科技有限公司 一种a相纳米纤维状氢氧化镍的合成方法
CN104466123A (zh) * 2014-12-27 2015-03-25 桂林理工大学 一种包覆β氢氧化镍的铝取代α氢氧化镍的制备方法
CN108475780A (zh) * 2016-01-05 2018-08-31 巴斯夫公司 用于碱性充电电池的氢氧化镍复合材料
CN109574090A (zh) * 2017-09-28 2019-04-05 比亚迪股份有限公司 氢氧化镍钴锰和正极材料及其制备方法和锂离子电池

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