WO2023143469A1

WO2023143469A1 - Positive electrode material precursor and preparation method therefor, positive electrode material and preparation method therefor

Info

Publication number: WO2023143469A1
Application number: PCT/CN2023/073438
Authority: WO
Inventors: 雷雨; 李光鑫; 许若愚; 夏圣安
Original assignee: 华为技术有限公司
Priority date: 2022-01-30
Filing date: 2023-01-20
Publication date: 2023-08-03
Also published as: CN116565188A

Abstract

Embodiments of the present application provide a positive electrode material precursor and a preparation method therefor, a positive electrode material and a preparation method therefor. The positive electrode material precursor comprises a metal oxide and a metal oxide precursor located on the surface of the metal oxide, the metal oxide is of a single crystal or single crystal-like structure, and the metal oxide precursor is of a polycrystal structure. According to the positive electrode material precursor and the positive electrode material prepared from the positive electrode material precursor in the present application, cracks generated from positive electrode material secondary particles in a charging and discharging circulation process can be effectively inhibited, structural stability of the positive electrode material is improved, and cycle performance of a battery is improved.

Description

Cathode material precursor and preparation method thereof, cathode material and preparation method thereof

This application claims the priority of the Chinese patent application submitted to the China Patent Office on January 30, 2022, with the application number 202210113230.3, and the application name "cathode material precursor and its preparation method, cathode material and its preparation method", all of which The contents are incorporated by reference in this application.

technical field

The embodiments of the present application relate to the technical field of secondary batteries, in particular, to positive electrode material precursors and preparation methods thereof, positive electrode materials and preparation methods thereof.

Background technique

Due to the advantages of high energy density, long service life, low self-discharge rate and environmental friendliness, lithium-ion batteries are widely used in power generation, power grid and power consumption in power systems. key energy storage medium. The gradual replacement of fuel vehicles by electric vehicles is the most important thing to replace with electric energy. At present, the lithium-ion batteries used in electric vehicles are mainly based on lithium iron phosphate and ternary cathode materials. Compared with the lithium iron phosphate cathode, the ternary cathode material is a kind of material with more development prospects. It combines the advantages of lithium cobalt oxide, lithium nickel oxide and lithium manganese oxide. It is a type of low cost, high capacity, and long life. A cathode material with good thermal stability and stable structure.

The rapid development of electric vehicles and energy storage industries has brought new opportunities for the development of lithium-ion batteries, but also put forward higher requirements for the energy density, safety performance, stability and cost of lithium-ion batteries. Increasing the nickel content in the ternary cathode material is one of the main methods to increase the energy density of the current ternary lithium-ion battery. However, with the increase of the nickel content, the electrochemical stability and safety of the material will decrease. This is because most of the commercialized high-nickel ternary cathode materials are composed of secondary particle balls with a particle size of 5-15 microns. These secondary particle spheres are formed by the agglomeration of nano primary grains. The nano primary grains have anisotropy in crystallographic orientation. During the delithiation process, the anisotropic volume change of these randomly arranged grains will lead to Anisotropic mechanical stress is generated between the grains. If these mechanical stresses cannot be released to the outside of the secondary grains in time, the stress will accumulate between the grains and eventually lead to intergranular cracks or grain cracking. Especially in the case of deep delithiation, the volume change and intergranular microcracks will become more obvious.

Contents of the invention

In view of this, the embodiment of the present application provides a positive electrode material precursor and its preparation method, a positive electrode material and its preparation method, the positive electrode material precursor of the present application and the positive electrode material prepared from the positive electrode material precursor have internal large-grain single crystal Or single crystal, polycrystalline composite structure formed by small primary grains on the outside, this composite structure can effectively suppress the cracks of the secondary particles of the positive electrode material during the charging and discharging process, so as to solve the problem of the existing positive electrode material to a certain extent. Easy cracking during charging and discharging leads to poor cycle performance of the battery.

Specifically, the first aspect of the embodiment of the present application provides a positive electrode material precursor, the positive electrode material precursor includes a metal oxide and a metal oxide precursor located on the surface of the metal oxide, and the metal oxide is a single crystal or single-crystal-like structure, and the metal oxide precursor has a polycrystalline structure.

The positive electrode material precursor in the embodiment of the present application has an inner core and an outer shell located on the surface of the inner core. The inner core is a metal oxide with a single crystal or similar single crystal structure, and the outer shell is a metal oxide precursor with a polycrystalline structure. That is, the positive electrode material precursor in the embodiment of the present application is a composite of a single crystal or a single crystal-like structure metal oxide and a polycrystalline structure metal oxide precursor, and the single crystal or single crystal-like metal oxide The oxide is located inside the secondary particle of the positive electrode material precursor, and the polycrystalline metal oxide precursor is located outside the secondary particle of the positive electrode material precursor. The external polycrystalline metal oxide precursor is an internal single crystal or single crystal The metal oxide is obtained by nucleation and growth as the seed crystal. The positive electrode material precursor of the embodiment of the present application has the advantages of both a single crystal or a single crystal-like structure and a polycrystalline structure, wherein the internal single crystal or single crystal-like structure is used as a seed crystal to ensure that the internal structure of the secondary particle of the positive electrode material precursor is dense , improve the mechanical structure stability of the secondary particles as a whole, and the positive electrode material prepared by using the positive electrode material precursor can also have the advantages of single crystal or single crystal structure and polycrystalline structure, and obtain good mechanical structure stability. During the cycle charge and discharge process, the single crystal or single crystal-like material in the core can provide stable mechanical properties, offset the stress, and make it difficult for cracks to occur inside, thereby improving the cycle stability and safety of the positive electrode material, and the cost is relatively single crystal Positive electrode material is low.

In the embodiment of the present application, the metal oxide located inside has a single-crystal or single-crystal-like structure, that is, the inside is a single-crystal or single-crystal-like particle, and the grain size of the metal oxide is 1 μm-5 μm. Single-crystal or single-crystal-like particles with larger particle sizes have higher mechanical strength, and they can effectively inhibit the secondary particle breakage when located inside the secondary particles, and improve the cycle stability and thermal stability of the positive electrode material prepared from the positive electrode material precursor sex.

In an embodiment of the present application, the primary grain diameter of the metal oxide precursor is less than 1 μm. Primary crystal grains with smaller grain diameters accumulate to form a shell, which can obtain a shell with a denser structure and improve the electrochemical performance of the positive electrode material.

In the embodiment of the present application, the metal oxide is spherical or spherical. The metal oxide with spherical or quasi-spherical particles has high mechanical strength as the inner core, and the introduction as a seed crystal is beneficial to the growth of the primary grain of the metal oxide precursor in the outer layer.

In one embodiment of the present application, the primary crystal grains of the metal oxide precursor grow randomly on the surface of the metal oxide. The primary crystal grains grow in a disordered manner, which is easy to control and prepare, and can meet certain application requirements.

In another embodiment of the present application, at least part of the primary crystal grains of the metal oxide precursor grow radially on the surface of the metal oxide along the radial direction of the secondary particles of the positive electrode material precursor. The radial radial arrangement of the primary crystal grains is conducive to effectively releasing the stress accumulated in the final positive electrode material during the charge-discharge cycle, reducing the accumulation of internal stress, thereby prolonging the cycle life of the positive electrode material.

In the embodiments of the present application, the material of the metal oxide precursor may be the precursor of various forms of metal oxide cathode materials. For example, the metal oxide precursor includes a metal oxide hydroxide precursor, a metal oxide oxide precursor, a metal oxide carbonate precursor, or a metal oxide oxyhydroxide precursor. The precursors in the above forms are easy to prepare and stable.

In the embodiment of the present application, the particle size of the secondary particles of the cathode material precursor is less than or equal to 50 μm. The secondary particles of the positive electrode material precursor are polycrystalline particles. Appropriate secondary particle size is conducive to the subsequent preparation of a positive electrode sheet with stable structure and stable electrochemical performance.

In the embodiment of the present application, the metal oxide is a metal oxide for a positive electrode of a lithium-ion battery, a metal oxide for a positive electrode of a sodium-ion battery, a metal oxide for a positive electrode of a potassium-ion battery, or a metal oxide for a positive electrode of a magnesium-ion battery; The metal oxide precursors are correspondingly the metal oxides for positive electrodes of lithium-ion batteries, the metal oxides for positive electrodes of sodium-ion batteries, the metal oxides for positive electrodes of potassium-ion batteries, or magnesium ions that have the same or different composition as the metal oxides. Precursors of metal oxides for battery positive electrodes.

In the embodiment of the present application, the metal oxide for the positive electrode of the lithium ion battery includes lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium titanium oxide, lithium iron phosphorus oxide, lithium nickel cobalt oxide, lithium One or more of nickel-manganese oxides and nickel-cobalt multi-component oxides.

The second aspect of the embodiment of the present application provides a method for preparing a positive electrode material precursor, including the following steps:

A metal oxide with a single crystal or a single crystal-like structure is used as a seed crystal, mixed with a metal oxide precursor raw material, and a positive electrode material precursor is obtained through a co-precipitation reaction. The positive electrode material precursor includes a metal oxide and a metal oxide located on the metal oxide The metal oxide precursor on the surface of the object, the metal oxide is a single crystal or a single crystal structure, and the metal oxide precursor is polycrystalline structure.

The preparation method of the positive electrode material precursor provided in the embodiment of the present application is to add a single crystal or a single crystal-like structure metal oxide positive electrode material to the raw material of the metal oxide positive electrode material precursor, and the single crystal or single crystal structure similar metal oxide positive electrode material It can be used as a seed crystal to promote the nucleation and growth of precursor grains. According to the heterogeneous nucleation mechanism, the precursor will preferentially nucleate and grow around the seed crystal, which can not only solve the problem of large disturbance in the nucleation stage of the existing precursor and loose growth inside the particle problem, and a composite precursor material with a single crystal or single crystal inside and a polycrystalline outside can be obtained. The single crystal or single crystal core can also provide good mechanical structure stability for the whole particle.

The third aspect of the embodiment of the present application provides a positive electrode material, the positive electrode material includes an inner layer and an outer layer located on the surface of the inner layer, the inner layer is a metal oxide positive electrode material with a single crystal or single crystal-like structure, so The outer layer is a polycrystalline metal oxide cathode material.

In the embodiment of the present application, the grain size of the metal oxide positive electrode material with a single crystal or similar single crystal structure in the inner layer is larger than the diameter of the primary grain of the metal oxide positive electrode material in the outer layer, thus forming a large inner and outer outer layer of the entire secondary particle. Structure of small grain distribution. The structure with large inside and small outside can not only obtain a stable inner layer structure, but also form a dense outer layer structure, thereby improving the overall mechanical structure stability of the secondary particles. During the cycle charge and discharge process, the inner layer of large particles It can provide stable mechanical properties, offset stress, and make cracks less likely to occur inside, thereby improving the cycle stability and safety of positive electrode materials.

In the embodiment of the present application, the grain size of the metal oxide positive electrode material with a single crystal or quasi-single crystal structure is 1 μm-5 μm. Single-crystal or single-crystal-like particles with larger particle sizes have higher mechanical strength, and being located inside secondary particles can effectively inhibit secondary particle breakage and improve the cycle stability and thermal stability of positive electrode materials.

In the embodiment of the present application, the diameter of the primary crystal grains of the polycrystalline metal oxide positive electrode material is less than 1 μm. The outer layer is formed by the accumulation of primary grains with smaller grain diameters, which can obtain a denser outer layer structure and improve the electrochemical performance of the positive electrode material.

In one embodiment of the present application, the primary crystal grains of the polycrystalline metal oxide positive electrode material grow randomly on the surface of the inner layer to form the outer layer. The primary crystal grains grow in a disordered manner, which is easy to control and prepare, and can meet certain application requirements.

In another embodiment of the present application, at least part of the primary crystal grains of the polycrystalline metal oxide positive electrode material grow radially on the surface of the inner layer along the radial direction of the secondary particles of the positive electrode material to form the outer layer. layer. The radial radial arrangement of the primary grains of the metal oxide cathode material precursor is conducive to the effective release of the stress accumulated in the final cathode material during the charge-discharge cycle, reducing the accumulation of internal stress, thereby prolonging the cycle life of the cathode material .

In the embodiment of the present application, the secondary particle size of the positive electrode material is less than or equal to 50 μm. Appropriate secondary particle size is conducive to the preparation of a positive electrode sheet with stable structure and stable electrochemical performance.

In the embodiment of the present application, the single-crystal or single-crystal-like structure metal oxide cathode material of the inner layer and the polycrystalline metal oxide cathode material of the outer layer are lithium-ion battery metal oxides of the same or different composition. Cathode material, metal oxide cathode material for sodium ion battery, metal oxide cathode material for potassium ion battery or metal oxide cathode material for magnesium ion battery.

In the embodiment of the present application, the lithium ion battery metal oxide positive electrode material includes lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium titanium oxide, lithium iron phosphorus oxide, lithium nickel cobalt oxide, lithium One or more of nickel-manganese oxides and nickel-cobalt multi-component oxides.

The fourth aspect of the embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

Mix the positive electrode material precursor described in the first aspect of the present application or the positive electrode material precursor prepared by the preparation method described in the second aspect of the embodiment of the present application with a metal salt, and obtain a positive electrode material after sintering, and the positive electrode material includes layer and an outer layer located on the surface of the inner layer, the inner layer is a metal oxide positive electrode material with a single crystal or single crystal structure, and the outer layer is a metal oxide positive electrode material with a polycrystalline structure.

In the embodiment of the present application, the sintering temperature is 600°C-800°C, the sintering time is 8-20 hours, and the sintering atmosphere is an oxygen atmosphere.

In the embodiment of the present application, the metal salt includes lithium salt, sodium salt, potassium salt or magnesium salt.

The preparation method of the embodiment of the present application has a simple process and is easy to realize large-scale production.

The fifth aspect of the embodiment of the present application provides a positive electrode sheet, and the positive electrode sheet includes the positive electrode material described in the third aspect of the embodiment of the present application. The positive electrode sheet of the embodiment of the present application has high stability and safety.

The sixth aspect of the embodiment of the present application provides a battery, the battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte and a separator between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet includes the first electrode sheet of the embodiment of the present application. The positive electrode sheet described in the five aspects. The battery of the embodiment of the present application has high stability and safety.

An embodiment of the present application further provides an electronic device, the electronic device including the battery described in the sixth aspect of the embodiment of the present application. The battery used in the electronic device in the embodiment of the present application has high stability and safety.

An embodiment of the present application further provides an energy storage system, the energy storage system including the battery described in the sixth aspect of the embodiment of the present application. The battery used in the energy storage system in the embodiment of the present application has high stability and safety.

Description of drawings

FIG. 1A is a schematic structural diagram of a positive electrode material precursor 100 provided by an embodiment of the present application;

FIG. 1B is a schematic structural view of a positive electrode material precursor 100 provided in another embodiment of the present application;

FIG. 2A is a schematic structural view of a positive electrode material 200 provided by an embodiment of the present application;

FIG. 2B is a schematic structural diagram of a positive electrode material 200 provided by another embodiment of the present application;

FIG. 3 is a schematic structural view of the positive electrode sheet 31 provided in the embodiment of the present application;

FIG. 4 is a schematic structural diagram of a battery 30 provided in an embodiment of the present application;

FIG. 5 is a schematic structural diagram of an electronic device 40 provided by an embodiment of the present application;

Fig. 6 is a schematic structural diagram of an energy storage system 50 provided by an embodiment of the present application;

The XRD (X-ray diffraction, X-ray diffraction) spectrum of the lithium ion battery positive electrode material precursor sample of Fig. 7 embodiment 1 and comparative example 1.

Detailed ways

The embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

Referring to FIG. 1A and FIG. 1B , FIG. 1A is a schematic structural diagram of a positive electrode material precursor 100 provided in an embodiment of the present application; FIG. 1B is a schematic structural diagram of a positive electrode material precursor 100 provided in another embodiment of the present application. The positive electrode material precursor 100 provided in the embodiment of the present application includes a core 101 and a shell 102 located on the surface of the core 101, the core 101 is a metal oxide, the core 101 has a single crystal or a single crystal-like structure, and the shell 102 includes a metal oxide precursor, The shell 102 has a polycrystalline structure. That is, the inner core 101 is a metal oxide particle, the inner core 101 is a single crystal or a single crystal-like particle, the outer shell 102 is composed of multiple primary crystal grains 1021 of metal oxide precursors, and the primary crystal grains of multiple metal oxide precursors 1021 grows on the surface of the metal oxide, that is, the inner core 101 .

The positive electrode material precursor 100 of the embodiment of the present application is a composite of a single crystal or a single crystal-like structure metal oxide and a polycrystalline structure metal oxide precursor, and the single crystal or single crystal-like metal oxide is located in the positive electrode material precursor 100 Inside the secondary particle, the polycrystalline metal oxide precursor is located outside the secondary particle of the positive electrode material precursor 100, and the external polycrystalline metal oxide precursor is seeded with the internal single crystal or single crystal-like metal oxide And nucleation growth is obtained. The positive electrode material precursor 100 of the embodiment of the present application has the advantages of both a single crystal or a single crystal structure and a polycrystalline structure, wherein the internal single crystal or single crystal structure is used as a seed crystal to ensure the internal structure of the secondary particle of the positive electrode material precursor Dense, improve the overall mechanical structure stability of secondary particles, Similarly, the positive electrode material prepared by using the positive electrode material precursor can also have the advantages of single crystal or single crystal structure and polycrystalline structure, and obtain good mechanical structure stability. Single crystal materials can provide stable mechanical properties, offset stress, and make it difficult for cracks to be generated inside, thereby improving the cycle stability and safety of positive electrode materials, and the cost is lower than that of single crystal positive electrode materials.

In the embodiment of the present application, the inner core 101 has a single crystal or a single crystal-like structure, and the grain size of the metal oxide with a single crystal or a single crystal-like structure in the inner core 101 is relatively large. Referring to Fig. 1A and Fig. 1B, in some embodiments, the entire inner core 101 is composed of a micron-sized single crystal or single crystal-like particle, that is, the inner core 101 is made of single crystal or single-crystal-like metal oxide particles with a larger particle size In this configuration, the grain size of the inner core 101 is larger than the diameter of the primary grain 1021 of the metal oxide precursor of the outer shell 102 . In the implementation manner of the present application, the metal oxide of the inner core 101 may have a spherical or spherical-like structure. In the present application, the grain size of the metal oxide positive electrode material with single crystal or quasi-single crystal structure is 1 μm-5 μm. Specifically, the grain size of the metal oxide cathode material with a single crystal or similar single crystal structure may be, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc. Single crystal or single crystal-like particles with larger particle size have higher mechanical strength, can effectively inhibit secondary particle breakage, and improve the cycle stability and thermal stability of the positive electrode material prepared from the positive electrode material precursor. And because the metal oxide precursor of the polycrystalline structure is grown on the outside of the single crystal or single crystal-like particles, the outside of the positive electrode material prepared from the positive electrode material precursor is also a metal oxide of the polycrystalline structure, such that the single crystal or The quasi-single crystal particles can withstand the concentrated tensile stress generated inside the secondary particles of the positive electrode material, and avoid cracks inside the secondary particles of the positive electrode material.

In the embodiment of the present application, the shell 102 is a polycrystalline structure. Referring to FIGS. 1A and 1B , the polycrystalline structure is formed by the accumulation of primary grains 1021 of multiple metal oxide precursors, that is, the shell 102 includes a plurality of stacked and agglomerated metals. Primary grains 1021 of oxide precursor. The primary crystal grains 1021 of the metal oxide precursor in the shell 102 are nanoscale or submicron grains, and the grain diameter is smaller than the grain diameter of the single crystal or single crystal structure metal oxide in the inner core 101, that is The positive electrode material precursor 100 of the present application is a composite structure with large grains inside and small outside, and single crystal inside and polycrystalline outside. This composite structure is conducive to making the positive electrode material prepared by the positive electrode material precursor 100 have a more stable structure and better It maintains structural stability during charge and discharge, and improves the cycle performance of positive electrode materials. In the embodiment of the present application, the primary grain diameter of the metal oxide precursor is less than 1 μm. In some embodiments, the primary grain diameter of the metal oxide precursor is 10 nm-800 nm. In some embodiments, the primary grain diameter of the metal oxide precursor is 50nm-500nm. In some embodiments, the primary grain diameter of the metal oxide precursor can be, for example, 10nm, 20nm, 30nm, 50nm, 80nm, 100nm, 120nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 600nm, 700nm, 800nm, 900nm, 950nm, etc. When the primary grains of the metal oxide precursor are spherical or spherical particles, the diameter of the primary grains is the maximum diameter of the spherical or spherical particles; when the primary grains of the metal oxide precursor are elongated or rod-shaped particles When , the primary grain diameter is the radial maximum dimension of long strip or rod-shaped particles.

In some embodiments of the present application, the primary crystal grains 1021 of the metal oxide precursor may be randomly grown and arranged on the surface of the inner core 101 . Referring to FIG. 1B, the primary crystal grains 1021 of the metal oxide precursor grow and accumulate in a disordered manner on the surface of the core 101 to form a shell 102, that is, the primary crystal grains 1021 of the metal oxide precursor grow randomly and accumulate on the surface of the core 101 in a non-oriented manner. .

In some other embodiments of the present application, the primary crystal grains 1021 of multiple metal oxide precursors in the outer shell 102 are grown and arranged on the surface of the inner core 101 . Referring to FIG. 1A, the primary crystal grains 1021 of the metal oxide precursor grow radially along the radial direction of the secondary particle 100 of the positive electrode material precursor and accumulate on the surface of the inner core 101 to form a shell 102, that is, the primary crystal grains 1021 of the metal oxide precursor It is an orientational growth arrangement, specifically a radial radial arrangement. Since the positive electrode material can inherit the grain arrangement structure of the positive electrode material precursor 100, the radial radial arrangement of the primary crystal grains 1021 of the metal oxide precursor is beneficial to make the stress accumulated in the final positive electrode material during the charge-discharge cycle process It can be effectively released to reduce the accumulation of internal stress, thereby prolonging the cycle life of the positive electrode material.

In the embodiment of the present application, the secondary particle size of the positive electrode material precursor 100 is less than or equal to 50 μm. In some embodiments, the secondary particle size of the cathode material precursor 100 may be 3 μm-50 μm. In some embodiments, the secondary particle size of the cathode material precursor 100 may be 10 μm-45 μm. In some embodiments, the secondary particle size of the cathode material precursor 100 may be 15 μm-40 μm. In some embodiments, the secondary particle size of the cathode material precursor 100 may be 20 μm-30 μm. The secondary particles of the positive electrode material precursor 100 may be spherical or quasi-spherical particles.

In the present application, the positive electrode material precursor 100 can be a positive electrode material precursor of different battery systems, for example, it can be a lithium ion battery, a sodium ion battery, a potassium ion battery, a magnesium ion battery system, and the like. In the embodiment of the present application, the single-crystal or single-crystal-like metal oxide of the inner core 101 can be the positive electrode material of different battery systems, and can be a metal oxide for lithium-ion battery positive electrodes (that is, lithium-ion battery metal oxide positive electrode materials), Metal oxides for anodes of sodium-ion batteries (i.e. metal oxide anode materials for sodium-ion batteries), metal oxides for anodes for potassium-ion batteries (i.e. metal oxide anode materials for potassium-ion batteries) or metal oxides for anodes for magnesium-ion batteries (magnesium ion battery metal oxide positive electrode material), etc.; then the metal oxide precursors of the shell 102 are respectively the same or different composition (that is, the same or different chemical formula) as the single crystal or similar single crystal structure metal oxide. Precursors of metal oxides for positive electrodes of lithium-ion batteries, metal oxides for positive electrodes of sodium-ion batteries, metal oxides for positive electrodes of potassium-ion batteries, or metal oxides for positive electrodes of magnesium-ion batteries. That is to say, in some embodiments, the metal oxide positive electrode material of the single crystal or single crystal structure of the inner core 101 is a metal oxide positive electrode material of a lithium ion battery, and correspondingly, the precursor of the metal oxide positive electrode material of the shell 102 is a lithium ion battery metal oxide precursors of cathode materials. In some embodiments, the metal oxide positive electrode material of the single crystal or single crystal-like structure of the inner core 101 is a metal oxide positive electrode material of a sodium ion battery, and correspondingly, the precursor of the metal oxide positive electrode material of the shell 102 is a metal oxide metal oxide of a sodium ion battery Precursors of cathode materials. In some embodiments, the metal oxide positive electrode material of the single crystal or single crystal-like structure of the inner core 101 is a metal oxide positive electrode material of a potassium ion battery, and correspondingly, the precursor of the metal oxide positive electrode material of the shell 102 is a metal oxide metal oxide of a potassium ion battery Precursors of cathode materials. In some embodiments, the metal oxide positive electrode material of the single crystal or single crystal-like structure of the core 101 is a metal oxide positive electrode material of a magnesium ion battery, and correspondingly, the precursor of the metal oxide positive electrode material of the shell 102 is a metal oxide metal oxide of a magnesium ion battery Precursors of cathode materials.

Wherein, "the metal oxide precursor of the outer shell 102 is corresponding to the metal oxide precursor of the inner core 101 respectively, and has the same or different composition (ie, the same or different The precursor of the metal oxide for the positive electrode of the lithium ion battery, the metal oxide for the positive electrode of the sodium ion battery, the metal oxide for the positive electrode of the potassium ion battery, or the metal oxide for the positive electrode of the magnesium ion battery of chemical formula) refers to the metal oxide of the shell 102 The precursor can be the precursor material corresponding to the metal oxide of the inner core 101, that is, the metal oxide precursor of the outer shell 102 can be oxidized and sintered to obtain a metal oxide having the same composition as the metal oxide of the inner core 101; The metal oxide precursor may not be the precursor material corresponding to the metal oxide of the core 101 , that is, the metal oxide precursor of the shell 102 is oxidized and sintered to obtain a metal oxide having a composition different from that of the metal oxide of the core 101 . For example, the inner core 101 is a single-crystal or single-crystal-like metal oxide cathode material LiNi _0.92 Co _0.04 Mn _0.04 O ₂ , and the shell ₁₀₂ can be a precursor material (Ni _0.92 Co _0.04 Mn _0.04 O ₂ Co _0.04 Mn _0.04 )(OH) ₂ , may also be the precursor material of other metal oxide cathode materials (for example, the hydroxide precursor material of nickel cobalt oxide (Ni _0.92 Co _0.08 )(OH) ₂ ).

In this application, the metal oxide precursor may be a precursor of various forms of metal oxide positive electrode materials, for example, it may be a hydroxide precursor including a metal oxide, an oxide precursor of a metal oxide, or a metal oxide precursor. Carbonate precursors or oxyhydroxide precursors of metal oxides, etc.

In the embodiment of the present application, the metal oxide for the positive electrode of the lithium ion battery, that is, the metal oxide positive electrode material of the lithium ion battery includes lithium cobalt oxide (such as lithium cobaltate LiCoO ₂ ), lithium nickel oxide (such as lithium nickelate LiNiO ₂ ), Lithium manganese oxides (such as lithium manganate LiMnO ₂ , lithium permanganate), lithium titanium oxides (such as lithium titanate), lithium iron phosphorus oxides (such as lithium iron phosphate), lithium nickel cobalt oxides (such as nickel cobalt Lithium oxide LiNi _a Co _1-a O ₂ ), lithium nickel manganese oxide (such as lithium nickel manganese oxide LiNi _a Mn _1-a O ₂ ), nickel cobalt multiple oxide (such as LiNi _a Co _b Mn _1-ab O ₂ , LiNi _a Co _b Al _1-ab O ₂ , LiNi _a Co _b Mn _c Al _{1- abc} O ₂ ), wherein, 0<a<1, 0<b<1, 0<c<1, 0<1-ab<1, 0<1-abc<1. The content of various elements in each oxide can be designed according to needs. Lithium-ion battery metal oxide cathode materials can be stoichiometric lithium-containing oxides, or non-stoichiometric lithium-containing oxides, such as lithium-ion battery metal oxide cathode materials Li _η Ni _a Co _b Mn _c Al ₁ In _-abc O ₂ , η can be any value greater than 0 and less than or equal to 2, 0≤a≤1, 0≤b≤1, 0≤c≤1, 0≤1-abc≤1.

In the embodiment of the present application, the metal oxide precursor of the outer shell 102 of the positive electrode material precursor 100 is set according to the pre-designed positive electrode material composition, and the metal oxide precursor can be the metal oxide positive electrode material of the lithium ion battery described above Hydroxide precursors, such as Co(OH) ₂ , LiNi(OH) ₂ , Mn(OH) ₂ , Ni _x Co _1-x (OH) ₂ , Ni _x Mn _1-x (OH) ₂ , Ni _x Co _y Mn _1-xy (OH) ₂ , Ni _x Co _y Al _1-xy (OH) ₂ , Ni _x Co _y Mn _z Al _1-xyz (OH) ₂ etc.; where 0<x<1, 0 <y<1, 0<z<1, 0<1-xy<1, 0<1-xyz<1.

In the embodiment of the present application, the metal oxide for the positive electrode of the sodium ion battery, that is, the metal oxide positive electrode material of the sodium ion battery may include sodium manganese oxide, sodium copper iron manganese oxide, sodium nickel iron manganese oxide, sodium copper nickel iron manganese One or more of oxides. In the embodiment of the present application, the metal oxide positive electrode material of the potassium ion battery may include potassium cobalt oxide, potassium manganese oxide, potassium iron manganese oxide, and the like. In the embodiment of the present application, the metal oxide positive electrode material of the magnesium ion battery may be one or more of magnesium vanadium oxide, magnesium cobalt manganese oxide, magnesium nickel manganese oxide, magnesium manganese oxide, and magnesium iron manganese oxide. kind. Correspondingly, the precursor of the metal oxide positive electrode material can be the precursor of the metal oxide positive electrode material of the sodium ion battery, the metal oxide positive electrode material of the potassium ion battery, and the metal oxide positive electrode material of the magnesium ion battery.

The embodiment of the present application also provides a method for preparing a positive electrode material precursor, including the following steps:

The single crystal or single crystal-like structure metal oxide is used as the seed crystal, mixed with the metal oxide precursor raw material, and the positive electrode material precursor is obtained through co-precipitation reaction. The positive electrode material precursor includes a core and a shell on the surface of the core. The core is a single A metal oxide positive electrode material with a crystalline or single-crystal-like structure, the outer shell is a polycrystalline structure, and the outer shell includes a metal oxide positive electrode material precursor.

In the embodiments of the present application, the raw materials of the metal oxide precursor are different according to the specific type of the metal oxide precursor. For example, a hydroxide precursor raw material of a metal oxide may include a metal source, sodium hydroxide and ammonia water. Wherein, the metal source is a metal salt, specifically a metal sulfate. For example, if the metal oxide precursor is Ni _x Co _y Mn _1-xy (OH) ₂ , the metal source includes nickel source, cobalt source and manganese source, specifically nickel sulfate salt, cobalt sulfate salt and manganese sulfate salt.

In the embodiment of the present application, the co-precipitation reaction is carried out under an inert atmosphere, and the inert atmosphere may be, for example, a nitrogen atmosphere.

It can be understood that the single-crystal or single-crystal-like metal oxide used as the seed crystal finally stays inside the positive electrode material precursor and becomes the inner core. The single-crystal or single-crystal-like metal oxide used as the seed crystal is consistent with the selection of specific components of the inner core 101 described above, and will not be repeated here. Similarly, the metal oxide precursor raw material is the raw material of the metal oxide precursor that can obtain the aforementioned shell 102 .

In this application, to prepare the core as LiNi _a Co _b Mn _1-ab O ₂ lithium oxide, the outer shell is Ni _x Co _y Mn _1-xy (OH) ₂ positive electrode material precursor LiNi _a Co _b Mn _1-ab O ₂ @(Ni _x Co _y Mn _1-xy )(OH) ₂ as an example, the preparation method of the positive electrode material precursor includes the following steps:

(1) preparation mixed metal salt solution: nickel sulfate, cobalt sulfate and manganese sulfate are x:y:1-x-y dissolving is mixed with mixed metal salt solution according to metal element mol ratio; The molar concentration of mixed metal salt solution can be Is 0.5mol/L-3mol/L, such as 2mol/L;

(2) Co-precipitate and grow the hydroxide precursor on the surface of the seed crystal: under nitrogen atmosphere, put the single crystal LiNi _a Co _b Mn _1-ab O ₂ lithium oxide as the seed crystal into the reactor, and in the reactor Add deionized water, then add ammonia solution and sodium hydroxide solution into the reaction kettle, adjust the temperature to 50°C-70°C, pH value to 10.0-12.0, stirring speed to 200rpm-300rpm, and then slowly add to (1) The prepared mixed metal salt solution, and the pH of the solution is controlled at 10.0-12.0 by ammonia water; Sodium chloride is mainly used as a co-precipitant, which can be slightly excessive relative to the metal salt; ammonia water is mainly used to adjust the pH of the system; for example, it can be added with an ammonia solution with a mass concentration of 8%-12%; the added molar concentration is 2mol/L-4mol/ L of sodium hydroxide;

(3) After the cathode material precursor particles grow to the target size, wash with water and dry to obtain the cathode material precursor.

In the embodiment of this application, the precursors with different shapes, different arrangements and different particle sizes can be obtained by adjusting the parameters such as the reaction time, stirring speed, and the addition speed of the mixed metal salt solution that affect the co-precipitation growth of the precursor. grain. Primary grains with radial distribution can be obtained by adjusting the lower rotational speed, the slower adding speed of the mixed metal salt solution, and the longer reaction time.

In the preparation method of the positive electrode material precursor provided in the embodiment of the present application, by adding a single crystal or a metal oxide with a single crystal structure to the raw material of the metal oxide positive material precursor, the single crystal or the metal oxide with a single crystal structure can be used as a seed crystal , to promote the nucleation and growth of precursor crystal grains. According to the heterogeneous nucleation mechanism, the precursor will preferentially nucleate and grow around the seed crystal. A composite precursor material with a single crystal or single-like crystal inside and a polycrystalline outside is obtained. The single crystal or single-like crystal inner core can also provide good mechanical structure stability for the whole particle.

Referring to FIG. 2A and FIG. 2B , FIG. 2A is a schematic structural diagram of a positive electrode material 200 provided by an embodiment of the present application. FIG. 2B is a schematic structural diagram of a positive electrode material 200 provided by another embodiment of the present application. The embodiment of the present application also provides a positive electrode material 200. The positive electrode material 200 includes an inner layer 201 and an outer layer 202 located on the surface of the inner layer 201. The inner layer 201 is a single crystal or single crystal-like structure metal oxide positive electrode material, and the outer layer 202 It is a metal oxide positive electrode material with a polycrystalline structure, that is, the inner layer 201 has a single crystal or similar single crystal structure, and the outer layer 202 has a polycrystalline structure. The positive electrode material 200 has the same core-shell structure as the positive electrode material precursor 100 , the inner layer 201 is the core, and the outer layer 202 is the shell.

The positive electrode material 200 of the embodiment of the present application is a composite of a single crystal or single crystal-like structure metal oxide positive electrode material and a polycrystalline structure metal oxide positive electrode material, and the single crystal or single crystal-like metal oxide positive electrode material is located in the positive electrode material 200 Inside the secondary particle, the polycrystalline metal oxide positive electrode material is located outside the secondary particle of the positive electrode material 200 . The positive electrode material 200 of the embodiment of the present application has the advantages of both a single crystal or a single crystal-like structure and a polycrystalline structure, wherein the internal single crystal or single crystal-like structure is used as a seed crystal to ensure that the internal structure of the secondary particle of the positive electrode material is dense, and the secondary particle structure is improved. The mechanical structure stability of the sub-particles as a whole, during the cycle charge and discharge process, the single crystal or single crystal-like material in the core can provide stable mechanical properties, offset the stress, and make it difficult for cracks to occur inside, thereby improving the cycle stability of the positive electrode material Safety and security, and the cost is lower than that of single crystal cathode materials.

In the embodiment of the present application, the inner layer 201 has a single-crystal or single-crystal-like structure, and the grain size of the metal oxide positive electrode material of the single-crystal or single-crystal-like structure in the inner layer 201 is relatively large. Referring to Figure 2A and Figure 2B, in some embodiments, the entire inner layer 201 is composed of a micron-sized single crystal or single crystal-like particle, that is, the inner layer 201 is made of a single crystal or single crystal-like positive electrode material with a larger particle size constitute. In the embodiment of the present application, the metal oxide positive electrode material of the inner layer 201 having a single crystal or similar single crystal structure has a spherical or spherical structure. In the embodiment of the present application, the grain size of the metal oxide positive electrode material with a single crystal or quasi-single crystal structure is 1 μm-5 μm. Specifically, the grain size of the metal oxide cathode material with a single crystal or similar single crystal structure may be, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc. Single crystal or single crystal-like particles have high mechanical strength, can effectively inhibit secondary particle breakage, and improve the cycle stability and thermal stability of positive electrode materials. Moreover, since the single crystal or single crystal-like particles grow outside the polycrystalline metal oxide positive electrode material, the single crystal or single crystal-like particles can withstand the concentrated tensile stress generated inside the secondary particles of the positive electrode material, avoiding the positive electrode material. Cracks occur inside the secondary particles of the material.

In the embodiment of the present application, referring to FIG. 2A and FIG. 2B , the outer layer 202 is a polycrystalline structure composed of a plurality of small-sized primary crystal grains 2021 of the metal oxide positive electrode material, and the primary crystal grains of the multiple metal oxide positive electrode materials Grains 2021 are grown on the surface of the metal oxide cathode material single crystal or single crystal-like grains in the inner layer 201. The primary crystal grains 2021 of the polycrystalline metal oxide cathode material in the outer layer 202 are nanoscale or submicron grains, and the grain diameter is smaller than that of the single crystal or single crystal-like structure metal oxide cathode material in the inner layer 201 The crystal grain size, that is, the positive electrode material 200 of this application is large inside the grain and small outside, single crystal inside and small outside. The polycrystalline composite structure is beneficial to make the positive electrode material 200 have a more stable structure, better maintain structural stability during charging and discharging, and improve the cycle performance of the positive electrode material. In the embodiment of the present application, the primary crystal grain diameter of the polycrystalline metal oxide positive electrode material is less than 1 μm. In some embodiments, the primary crystal grain diameter of the polycrystalline metal oxide positive electrode material is 10 nm-800 nm. In some embodiments, the primary crystal grain diameter of the polycrystalline metal oxide positive electrode material is 50 nm-500 nm. In some embodiments, the primary grain diameter of the polycrystalline metal oxide positive electrode material may be, for example, 10nm, 20nm, 30nm, 50nm, 80nm, 100nm, 120nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm , 600nm, 700nm, 800nm, 900nm, 950nm, etc. When the primary grain of the metal oxide positive electrode material with polycrystalline structure is a spherical or spherical particle, the primary grain diameter is the maximum diameter of the spherical or spherical particle; when the primary grain of the metal oxide positive electrode material with polycrystalline structure is For elongated or rod-shaped particles, the primary grain diameter is the radial maximum dimension of the elongated or rod-shaped particles.

In some embodiments of the present application, the primary grains 2021 of the polycrystalline metal oxide cathode material may be randomly grown and arranged on the surface of the inner layer 201 . Referring to FIG. 2B , the primary crystal grains 2021 of the polycrystalline metal oxide cathode material grow in disorder and accumulate on the surface of the inner layer 201 to form the outer layer 202, that is, the primary crystal grains 2021 of the polycrystalline metal oxide cathode material are non-oriented. Randomly grow and accumulate on the surface of the inner layer 201 .

In other embodiments of the present application, the primary crystal grains 2021 of the polycrystalline metal oxide positive electrode material in the outer layer 202 are grown and arranged on the surface of the inner layer 201 . Referring to FIG. 2A , the primary crystal grains 2021 of the polycrystalline metal oxide positive electrode material grow radially along the radial direction of the secondary particle 200 of the positive electrode material and accumulate on the surface of the inner layer 201 to form the outer layer 202, that is, the polycrystalline metal oxide positive electrode The primary crystal grains 2021 of the material are arranged in an orientational growth, specifically in a radial radial arrangement. The radial radial arrangement of the primary crystal grains 2021 of the polycrystalline metal oxide cathode material in the outer layer 202 is conducive to effectively releasing the stress accumulated in the cathode material during charge and discharge cycles and improving the structural stability of the cathode material.

In the embodiment of the present application, the particle size of the secondary particles of the positive electrode material 200 is less than or equal to 50 μm. In some embodiments, the size of the secondary particles of the positive electrode material 200 may be 3 μm-50 μm. In some embodiments, the size of the secondary particles of the positive electrode material 200 may be 10 μm-45 μm. In some embodiments, the size of the secondary particles of the positive electrode material 200 may be 15 μm-40 μm. In some embodiments, the size of the secondary particles of the positive electrode material 200 may be 20 μm-30 μm. The secondary particles of the positive electrode material precursor 100 may be spherical or quasi-spherical particles.

In the present application, the positive electrode material 200 may be a positive electrode material of different battery systems, such as a lithium ion battery, a sodium ion battery, a potassium ion battery, a magnesium ion battery, and the like. In the embodiment of the present application, the inner layer 201 and the outer layer 202 are the metal oxide cathode material of the same battery system. In the embodiment of the present application, the single-crystal or single-crystal-like metal oxide positive electrode material of the inner layer 201 and the polycrystalline metal oxide positive electrode material of the outer layer 202 can be lithium-ion battery metal oxides with the same or different compositions. Cathode material, metal oxide cathode material for sodium ion battery, metal oxide cathode material for potassium ion battery or metal oxide cathode material for magnesium ion battery. For example, the inner layer 201 is a single-crystal or quasi-single-crystal metal oxide cathode material LiNi _0.92 Co _0.04 Mn _0.04 O ₂ , while the outer layer 202 can be LiNi _0.92 Co _0.04 Mn _0.04 O ₂ which is also a polycrystalline metal oxide cathode material. , and may also be other metal oxide cathode materials (such as nickel cobalt oxide LiNi _0.92 Co _0.08 O ₂ ) having a composition different from LiNi _0.92 Co _0.04 Mn _0.04 O ₂ .

In the embodiment of the present application, the lithium ion battery metal oxide cathode material includes lithium cobalt oxide (such as lithium cobaltate LiCoO ₂ ), lithium nickel oxide (such as lithium nickelate LiNiO ₂ ), lithium manganese oxide (such as lithium manganate LiMnO ₂ , lithium permanganate), lithium titanium oxide (such as lithium titanate), lithium iron phosphorus oxide (such as lithium iron phosphate), lithium nickel cobalt oxide (such as lithium nickel cobaltate LiNi _a Co _1-a O ₂ ), lithium nickel manganese oxide (such as lithium nickel manganese oxide LiNi _a Mn _1-a O ₂ ), nickel cobalt multiple oxides (such as lithium nickel cobalt manganese oxide LiNi _a Co _b Mn _1-ab O ₂ , nickel cobalt aluminum One or more of LiNi _a Co _b Al _1-ab O ₂ , lithium nickel cobalt manganese aluminate LiNi _a Co _b Mn _c Al _1-abc O ₂ ), wherein, 0<a<1, 0<b<1,0<c<1,0<1-ab<1,0<1-abc<1. The content of various elements in each oxide can be designed according to needs. Metal oxide cathode materials for lithium-ion batteries can be either stoichiometric lithium-containing oxides or non-chemical In stoichiometric lithium-containing oxides, such as Li _η Ni _a Co _b Mn _c Al _1-abc O ₂ in metal oxide cathode materials for lithium-ion batteries, η can be any value greater than 0 and less than or equal to 2, 0≤a≤ 1, 0≤b≤1, 0≤c≤1, 0≤1-abc≤1.

In the embodiment of the present application, the metal oxide positive electrode material of the sodium ion battery may be one or more of sodium manganese oxide, sodium copper iron manganese oxide, sodium nickel iron manganese oxide, sodium copper nickel iron manganese oxide . In the embodiment of the present application, the metal oxide positive electrode material of the potassium ion battery may include potassium cobalt oxide, potassium manganese oxide, potassium iron manganese oxide, and the like. In the embodiment of the present application, the metal oxide positive electrode material of the magnesium ion battery may be one or more of magnesium vanadium oxide, magnesium cobalt manganese oxide, magnesium nickel manganese oxide, magnesium manganese oxide, and magnesium iron manganese oxide. kind.

The embodiment of the present application also provides a method for preparing a positive electrode material, comprising the following steps:

The positive electrode material precursor 100 mentioned above in this application is mixed with a metal salt, and the positive electrode material is obtained after sintering. The positive electrode material includes an inner layer and an outer layer located on the surface of the inner layer, and the inner layer is a single crystal or single crystal-like structure metal oxide positive electrode material, the outer layer is a polycrystalline structure metal oxide cathode material.

In the embodiment of the present application, the sintering temperature may be 600°C-800°C, for example, 600°C, 650°C, 680°C, 700°C, 750°C, 800°C. In the embodiment of the present application, the sintering time may be 8-20 hours, for example, 8 hours, 10 hours, 12 hours, 15 hours, 20 hours. The sintering atmosphere is an oxygen atmosphere. The oxygen concentration in the oxygen atmosphere can be controlled at 19%-100% by volume.

In the embodiment of the present application, the metal salt is selected according to the positive electrode material of different battery systems, and the metal salt can be lithium salt, sodium salt, potassium salt or magnesium salt. In the embodiment of the present application, for the positive electrode material of lithium ion battery, the metal salt is lithium salt; for the positive electrode material of sodium ion battery, the metal salt is sodium salt; for the positive electrode material of potassium ion battery, the metal salt is potassium salt; for the positive electrode material of magnesium ion battery, the metal salt is potassium salt; The material, the metal salt is a magnesium salt.

In the implementation manner of the present application, the lithium salt can be, for example, one or more of lithium hydroxide, lithium carbonate, lithium nitrate, and lithium oxalate. The lithium salt can be added according to the molar ratio of non-lithium metals (such as transition metals Ni, Co, Mn, etc.) and lithium in the positive electrode material precursor 100 as 1: (1～1.1), and the transition metal in the positive electrode material precursor 100 The element content can be obtained through ICP (Inductive Coupled Plasma Emission Spectrometer, Inductively Coupled Plasma Emission Spectrometer) characterization. In the embodiment of the present application, the sodium salt can be, for example, one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate. In the embodiment of the present application, the potassium salt can be specifically, for example, one or more of potassium hydroxide, potassium carbonate, and potassium bicarbonate. In the embodiment of the present application, for example, the magnesium salt may be one or more of magnesium hydroxide and magnesium carbonate.

The preparation method of the positive electrode material in the embodiment of the present application is prepared by using the precursor of the positive electrode material provided in the embodiment of the present application. After sintering at a temperature of 600-800 ° C, the positive electrode material of single crystal or single crystal and polycrystalline composite can be obtained without using Very high temperature calcination operation for the synthesis of single crystals or single-like crystals.

Referring to FIG. 3 , the embodiment of the present application also provides a positive electrode sheet 31. The positive electrode sheet 31 includes a current collector 301 and a positive electrode material layer 302 disposed on the current collector 301. The positive electrode material layer 302 includes the positive electrode material 200 mentioned above in this application. The current collector 301 is a conventional positive electrode current collector, such as aluminum foil or the like. The positive electrode material layer 302 may also include a conductive agent, a binder, and the like.

Referring to FIG. 4 , the embodiment of the present application also provides a battery 30 . The battery 30 includes the positive electrode sheet provided above in the embodiment of the present application, that is, includes the positive electrode material 200 provided above in the embodiment of the present application. The battery 30 may be a lithium ion secondary battery, a sodium ion secondary battery, a potassium ion secondary battery, a magnesium ion secondary battery, or the like. In some embodiments, the battery 30 includes a positive electrode sheet 31 , a negative electrode sheet 32 , an electrolyte 33 and a separator 34 . Taking lithium-ion battery as an example, during the charging process, under the action of an external circuit, lithium ions are extracted from the positive active material, inserted into the negative electrode through the electrolyte diaphragm, and at the same time, the positive electrode loses electrons and flows out of the external circuit through the current collector; The process is reversed, lithium ions come out from the negative electrode and return to the positive electrode, and at the same time, electrons move from the negative electrode to the positive electrode through the external circuit and do work externally.

Referring to FIG. 5 , the embodiment of the present application further provides an electronic device 40 , and the electronic device 40 includes the battery 30 provided above in the embodiment of the present application. The electronic equipment 40 may include various consumer electronic products, such as mobile phones, tablet computers, mobile power supplies, Laptops, notebook computers and other wearable or mobile electronic devices, televisions, DVD players, VCRs, camcorders, radios, cassette players, stereos, record players, CD players, home office equipment, home electronic healthcare equipment, and It can be electronic products such as automobiles and energy storage devices. In some embodiments, the electronic device 40 includes a casing 41 , electronic components (not shown in the figure) contained in the casing 41 and a battery 30 , and the battery 30 supplies power to the electronic device 40 .

Referring to Fig. 6, the embodiment of the present application also provides an energy storage system 50, the energy storage system 50 includes a battery pack 501 and a battery management system 502 electrically connected to the battery pack 501, the battery pack 501 includes the battery provided above in the embodiment of the present application 30.

The embodiments of the present application will be further described below in terms of multiple embodiments.

Example 1

Synthesis of LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ precursor of cathode material for lithium ion battery:

(1) Preparation of nickel-cobalt-manganese metal salt solution: nickel sulfate salt, cobalt sulfate salt and manganese sulfate salt are dissolved according to the Ni, Co, Mn molar ratio of 92:4:4 to prepare 2mol/L evenly mixed nickel-cobalt-manganese metal saline solution;

(2) preparation mass concentration is that 10wt.% ammonia solution and concentration are 4mol/L sodium hydroxide solution;

(3) 1 kg of single crystal LiNi _0.92 Co _0.04 Mn _0.04 O ₂ lithium oxide with a grain size of 2 μm is put into the reactor as a seed crystal, and deionized water is added in the reactor, and then the prepared ammonia solution and sodium hydroxide aqueous solution into the reaction kettle, adjust the temperature to 70°C, the pH value to 11.0, and the stirring speed to 300rpm, then slowly add the nickel-cobalt-manganese metal solution prepared in (1), and control the pH of the solution by ammonia water In 11.0.

(4) After the precursor particle grows to 15 microns, it is washed and dried with deionized water to obtain the cathode material precursor LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ .

Synthesis of cathode material LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @LiNi _0.92 Co _0.04 Mn _0.04 O ₂ :

(1) Fully mix the positive electrode material precursor LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ prepared above to obtain a mixture, and the lithium hydroxide is transitioned according to the precursor The molar ratio of metal (including Ni, Co, Mn) to lithium in lithium hydroxide is 1:1.01;

(2) The mixture in (1) is placed in a muffle furnace for calcination, the calcination temperature is 720° C., the calcination time is 16 hours, the calcination atmosphere is a pure oxygen atmosphere, and the calcination is naturally cooled after the calcination;

(3) The powder obtained after cooling in (2) was crushed, sieved, demagnetized, and then vacuum packaged to obtain the positive electrode material LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @LiNi _0.92 Co _0.04 Mn _0.04 O ₂ .

The precursor particles and positive electrode materials prepared in the examples are cut by FIB (Focused Ion beam, focused ion beam), and the cross-sectional morphology of the particles is observed by SEM (Scanning electron microscope, scanning electron microscope). The body particles are large in diameter and small in the outside, the inner core is single crystal, the outer shell is polycrystalline and the primary grains of the outer shell are radially distributed; the positive electrode material particles are also large in the inner diameter and small in the outer, and the inner layer is relatively Large-sized single-crystal particles, the outer layer is polycrystalline and the outer layer of small-diameter primary grains presents a radial distribution.

Preparation of positive electrode sheet: Add the positive electrode material, polyvinylidene fluoride (PVDF), and conductive agent super P into N-methylpyrrolidone (NMP) according to the mass ratio of 90:5:5, stir and mix well to obtain a slurry, and The slurry is coated on an aluminum foil current collector, dried, cold-pressed, and cut to obtain a positive electrode sheet.

Lithium-ion battery preparation: The positive electrode sheet prepared above, lithium sheet, electrolyte solution (1mol/L LiPF ₆ ) and separator were made into a 2032 button battery.

Comparative example 1

The synthesis of the precursor of the positive electrode material of lithium ion battery (Ni _0.92 Co _0.04 Mn _0.04 ) (OH) ₂ , the difference between Comparative Example 1 and Example 1 is that the single crystal LiNi _0.92 Co _0.04 is not added in step (3) of Comparative Example 1 Mn _0.04 O ₂ lithium oxide was used as the seed crystal, and other operations were the same.

According to the same method as in Example 1, the positive electrode _material LiNi _0.92 Co 0.04 Mn _0.04 O ₂ was prepared by using the positive electrode material precursor (Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ in Comparative Example 1.

According to the same method as in Example 1, the positive electrode sheet and battery were prepared using the positive electrode material LiNi _0.92 Co _0.04 Mn _0.04 O ₂ in Comparative Example 1.

Adopt X-ray diffraction (X-ray diffraction, XRD) instrument to test the lithium ion battery cathode material precursor sample of embodiment 1 and comparative example 1, the X-ray diffraction pattern that obtains is as shown in Figure 7, and Figure 7 is embodiment 1 and The XRD (X-ray diffraction, X-ray diffraction) spectrum of the lithium ion battery cathode material precursor sample of comparative example 1. Comparing the peak position in Fig. 7 with the JCPDS (Joint Committee on Powder Diffraction Standards, powder diffraction standard) card, it can be known that R- The layered compound diffraction peaks of the 3m space group and the hydroxide precursor diffraction peaks of the P-3m1 space group, while only the P-3m1 space group exists in the X-ray diffraction pattern of the lithium ion battery cathode material precursor sample of Comparative Example 1 Diffraction peaks of hydroxide precursors.

The batteries prepared in Example 1 and Comparative Example 1 were charged and discharged at 2525°C at 0.1C/0.1C and 1C/1C charge and discharge rates in the voltage range of 3.0V-4.3V, and the battery was recorded. The first-cycle charge-discharge capacity and 100-cycle cycle retention rate are shown in Table 1.

Table 1

It can be seen from the results in Table 1 that the battery of Example 1 of the present application exhibits significantly better cycle stability than the battery of Comparative Example 1, and the same first cycle charge and discharge performance as the battery of Comparative Example 1. This is mainly because the positive electrode material used in the battery of Example 1 of the present application has a single crystal polycrystalline composite structure, and the single crystal grain size is large inside, and the polycrystalline primary grain diameter is small outside, and the internal single crystal can better Withstand the concentrated tensile stress, and the external polycrystalline can effectively release the stress to the outside of the secondary particles, thereby inhibiting the formation of cracks in the secondary particles, improving the structural stability of the secondary particles of the positive electrode material, and improving the cycle performance of the battery.

Example 2

Synthesis of LiCoO ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ precursor of cathode material for lithium ion battery:

(1) Preparation of nickel-cobalt-manganese metal salt solution: nickel sulfate salt, cobalt sulfate salt and manganese sulfate salt are dissolved according to Ni, Co, Mn molar ratio of 92:4:4 to prepare 2.5mol/L evenly mixed nickel-cobalt-manganese Metal salt solution;

(2) preparation mass concentration is that 12wt.% ammonia solution and concentration are 3mol/L sodium hydroxide solution;

(3) Put 1 kg of single crystal LiCoO ₂ lithium oxide with a grain size of 3 μm as a seed crystal into the reactor, add deionized water into the reactor, and then add the prepared ammonia solution and sodium hydroxide solution In the reaction kettle, adjust the temperature to 70°C, the pH value to 11.0, and the stirring speed to 300rpm, then slowly add the nickel-cobalt-manganese metal solution prepared in (1), and control the pH of the solution to 11.0 with ammonia water.

(4) After the precursor particle grows to 15 microns, it is washed and dried with deionized water to obtain the positive electrode material precursor LiCoO ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ . The primary grains of the obtained precursor particles are large on the inside and small on the outside, the inner layer has a single crystal/single crystal morphology, and the outer layer has a polycrystalline morphology and the outer primary grains are radially distributed.

Synthesis of cathode material LiCoO ₂ @LiNi _0.92 Co _0.04 Mn _0.04 O ₂ :

The anode material precursor LiCoO ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ prepared above was used to prepare an anode material in the same manner as in Example 1.

The preparation of the positive electrode sheet and the battery are the same as in Example 1.

Example 3

Synthesis of LiCoO ₂ @(Ni _0.65 Co _0.15 Mn _0.20 )(OH) ₂ precursor of cathode material for lithium ion battery:

(1) Preparation of nickel-cobalt-manganese metal salt solution: nickel sulfate salt, cobalt sulfate salt and manganese sulfate salt are dissolved according to the Ni, Co, Mn molar ratio of 65:15:20 to prepare 2mol/L evenly mixed nickel-cobalt-manganese metal saline solution;

(3) Put 1 kg of single crystal LiCoO ₂ lithium oxide with a grain size of 3 μm as a seed crystal into the reactor, add deionized water into the reactor, and then add the prepared ammonia solution and sodium hydroxide solution In the reaction kettle, adjust the temperature to 70°C, the pH value to 11.0, and the stirring speed to 800rpm, then slowly add the nickel-cobalt-manganese metal solution prepared in (1), and control the pH of the solution to 11.0 with ammonia water.

(4) After the precursor particle grows to 12 microns, it is washed and dried with deionized water to obtain the positive electrode material precursor LiCoO ₂ @(Ni _0.65 Co _0.15 Mn _0.20 )(OH) ₂ . The primary grains of the obtained precursor particles are large on the inside and small on the outside, the inner layer has a single crystal/like single crystal morphology, and the outer layer has a polycrystalline morphology and the primary grains of the outer layer show a disordered distribution.

Synthesis of cathode material LiCoO ₂ @LiNi _0.65 Co _0.15 Mn _0.20 O ₂ :

The cathode material precursor LiCoO ₂ @(Ni _0.65 Co _0.15 Mn _0.20 )(OH) ₂ prepared above was used to prepare the cathode material in the same manner as in Example 1.

The precursor particles and positive electrode materials prepared in the examples are cut by FIB (Focused Ion beam, focused ion beam), and the cross-sectional morphology of the particles is observed by SEM (Scanning electron microscope, scanning electron microscope). The body particles have a grain diameter that is large inside and small outside, the inner core is a single crystal shape, the outer shell is polycrystalline, and the primary grains of the outer shell are distributed in a disordered manner; the positive electrode material particles are also large inside and small outside the grain diameter, and the inner layer It is a large-sized single-crystal particle, and the outer layer is polycrystalline, and the outer layer of small-diameter primary grains presents a disorderly distribution.

Comparative example 2

Lithium-ion battery anode material precursor (Ni _0.65 Co _0.15 Mn _0.20 ) (OH) ₂ synthesis, the difference between Comparative Example 2 and Example 3 is that Comparative Example 2 does not add single crystal LiCoO ₂ lithium oxide in step (3). material as a seed crystal, and the other operations are the same.

According to the same method as in Example 3, _the positive electrode material LiNi _0.65 Co 0.15 Mn _0.20 O ₂ was prepared by using the positive electrode material precursor (Ni _0.65 Co _0.15 Mn _0.20 )(OH) ₂ in Comparative Example 2.

According to the same method as in Example 1, the positive electrode sheet and battery were prepared using the positive electrode material LiNi _0.65 Co _0.15 Mn _0.20 O ₂ in Comparative Example 2.

Example 4

Synthesis of LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )CO ₃ precursor for lithium-ion battery cathode material:

(2) preparation mass concentration is that 9wt.% ammonia solution and concentration are 4mol/L sodium bicarbonate aqueous solution;

(3) 1 kg of single crystal LiNi _0.92 Co _0.04 Mn _0.04 O ₂ lithium oxide with a grain size of 2 μm is put into the reactor as a seed crystal, and deionized water is added in the reactor, and then the prepared ammonia solution and sodium bicarbonate aqueous solution into the reaction kettle, adjust the temperature to 70°C, the pH value to 11.0, and the stirring speed to 300rpm, then slowly add the nickel-cobalt-manganese metal solution prepared in (1), and control the pH of the solution by ammonia water In 11.0.

(4) After the precursor particle grows to 15 microns, it is washed and dried with deionized water to obtain the cathode material precursor LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )CO ₃ .

(1) The cathode material precursor LiNi _0.92 Co _0.04 Mn _0.04 O ₂ @(Ni _0.92 Co _0.04 Mn _0.04 )CO ₃ prepared above is fully mixed to obtain a mixture, and the lithium hydroxide is based on the transition metal in the precursor ( Including Ni, Co, Mn) and lithium in lithium hydroxide in a molar ratio of 1:1.01;

The precursor particles and positive electrode materials prepared in the examples are cut by FIB (Focused Ion beam, focused ion beam), and the cross-sectional morphology of the particles is observed by SEM (Scanning electron microscope, scanning electron microscope). The body particles are large in diameter and small in the outside, the inner core is single crystal, the outer shell is polycrystalline and the primary grains of the outer shell are radially distributed; the positive electrode material particles are also large in the inner diameter and small in the outer, and the inner layer is relatively Large-sized single-crystal particles, the outer layer is polycrystalline and the outer layer of small-diameter primary grains is radially distributed.

Example 5

Synthesis of NaNi _0.5 Mn _0.5 O ₂ @(Ni _0.33 Fe _0.33 Mn _0.33 )(OH) ₂ precursor of cathode material for sodium ion battery:

(1) Preparation of nickel-iron-manganese metal salt solution: dissolving nickel sulfate, ferrous sulfate and manganese sulfate according to Ni, Fe, Mn molar ratio of 1:1:1 to prepare 2mol/L uniformly mixed nickel, cobalt and manganese Metal salt solution;

(2) preparation mass concentration is that 10wt.% ammonia solution and concentration are 5mol/L sodium hydroxide solution;

(3) 1 kg grain size is 2 μ m single crystal O3 phase NaNi _0.5 Mn _0.5 O ₂ oxide is dropped in the reactor as the crystal seed, adds deionized water in the reactor, then the ammoniacal solution prepared and Sodium hydroxide aqueous solution is added in the reaction kettle, adjust temperature to be 70 ℃, pH value is 11.0, stirring speed is 300rpm, then slowly add the nickel-cobalt-manganese metal solution prepared in (1), and the pH of the solution is controlled at 11.0.

(4) After the precursor particle grows to 8 microns, it is washed and dried with deionized water to obtain the positive electrode material precursor NaNi _0.5 Mn _0.5 O ₂ @(Ni _0.33 Fe _0.33 Mn _0.33 )(OH) ₂ .

Synthesis of cathode material NaNi _0.5 Mn _0.5 O ₂ @NaNi _0.33 Fe _0.33 Mn _0.33 O ₂ :

(1) The cathode material precursor NaNi _0.5 Mn _0.5 O ₂ @(Ni _0.33 Fe _0.33 Mn _0.33 )(OH) ₂ prepared above is fully mixed with sodium carbonate to obtain a mixture. , Fe, Mn) and the molar ratio of lithium in lithium carbonate is 1:1.03 to add;

(2) The mixture in (1) is placed in a muffle furnace for calcination, the calcination temperature is 850° C., the calcination time is 16 hours, the calcination atmosphere is an air atmosphere, and the calcination is naturally cooled after the calcination;

(3) The powder obtained after cooling in (2) was crushed, sieved, demagnetized and then vacuum packaged to obtain the positive electrode material NaNi _0.5 Mn _0.5 O ₂ @NaNi _0.33 Fe _0.33 Mn _0.33 O ₂ .

Preparation of positive electrode sheet: Add the positive electrode material, polyvinylidene fluoride (PVDF), and conductive agent super P according to the mass ratio of 80:10:10, into N-methylpyrrolidone (NMP), stir and mix evenly to obtain a slurry, and The slurry is coated on an aluminum foil current collector, dried, cold-pressed, and cut to obtain a positive electrode sheet.

Preparation of sodium-ion battery: The positive electrode sheet prepared above, sodium sheet, electrolyte solution (1mol/L NaPF ₆ ) and separator were made into a 2032 button battery.

The batteries prepared in Examples 2-4 and Comparative Example 2 were charged and discharged at 2525°C at 0.1C/0.1C and 1C/1C charge and discharge rates in the voltage range of 3.0V-4.3V, and The first-cycle charge-discharge capacity and 100-cycle capacity retention rate of the battery were recorded, and the results are shown in Table 2.

Table 2 The first-cycle charge-discharge capacity and cycle 100-cycle capacity retention of the battery of Example 2-4

From the results in Table 2, it can be seen that the batteries of Example 2 and Example 4 exhibit significantly better cycle stability than the battery of Comparative Example 1, and the same first cycle charge and discharge performance as the battery of Comparative Example 1. The battery of Example 3 exhibited significantly better cycle stability than the battery of Comparative Example 2, and comparable first cycle charge and discharge performance to the battery of Comparative Example 2.

Claims

A positive electrode material precursor, characterized in that the positive electrode material precursor includes a metal oxide and a metal oxide precursor located on the surface of the metal oxide, the metal oxide is a single crystal or a single crystal-like structure, The metal oxide precursor has a polycrystalline structure.
The positive electrode material precursor according to claim 1, characterized in that the grain size of the metal oxide is 1 μm-5 μm.
The positive electrode material precursor according to claim 1 or 2, characterized in that the primary grain diameter of the metal oxide precursor is less than 1 μm.
The positive electrode material precursor according to any one of claims 1-3, characterized in that the metal oxide is spherical or quasi-spherical.
The positive electrode material precursor according to any one of claims 1-4, characterized in that the primary crystal grains of the metal oxide precursor grow in disorder on the surface of the metal oxide.
The positive electrode material precursor according to any one of claims 1-4, wherein at least part of the primary crystal grains of the metal oxide precursor are in the radial direction of the secondary particles of the positive electrode material precursor radial growth on the surface of the metal oxide.
The positive electrode material precursor according to any one of claims 1-6, wherein the metal oxide precursor comprises a hydroxide precursor of a metal oxide, an oxide precursor of a metal oxide, a metal oxide Carbonate precursors of metal oxides or oxyhydroxide precursors of metal oxides.
The cathode material precursor according to any one of claims 1-7, characterized in that, the secondary particle size of the cathode material precursor is less than or equal to 50 μm.
The positive electrode material precursor according to any one of claims 1-8, wherein the metal oxide is a metal oxide for the positive electrode of a lithium-ion battery, a metal oxide for a positive electrode of a sodium-ion battery, or a positive electrode for a potassium-ion battery. Metal oxides or metal oxides for positive electrodes of magnesium ion batteries; the precursors of the metal oxides are respectively the metal oxides for positive electrodes of lithium ion batteries and the positive electrodes of sodium ion batteries that have the same or different composition as the metal oxides. Precursors of metal oxides, metal oxides for positive electrodes of potassium ion batteries, or metal oxides for positive electrodes of magnesium ion batteries.
The positive electrode material precursor according to claim 9, wherein the metal oxide for the positive electrode of the lithium ion battery comprises lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium titanium oxide, lithium iron phosphorus One or more of oxides, lithium nickel-cobalt oxides, lithium nickel-manganese oxides, and nickel-cobalt multiple oxides.
A kind of preparation method of positive electrode material precursor, is characterized in that, comprises the following steps:

A metal oxide with a single crystal or a single crystal-like structure is used as a seed crystal, mixed with a metal oxide precursor raw material, and a positive electrode material precursor is obtained through a co-precipitation reaction. The positive electrode material precursor includes a metal oxide and a metal oxide located on the metal oxide The metal oxide precursor on the surface of the object, the metal oxide is a single crystal or a single crystal-like structure, and the metal oxide precursor is a polycrystalline structure.
A positive electrode material, characterized in that the positive electrode material comprises an inner layer and an outer layer located on the surface of the inner layer, the inner layer is a single crystal or single crystal-like structure metal oxide positive electrode material, and the outer layer is Polycrystalline metal oxide cathode material.
The positive electrode material according to claim 12, characterized in that, the grain size of the metal oxide positive electrode material with single crystal or single crystal-like structure is 1 μm-5 μm.
The positive electrode material according to claim 12 or 13, wherein the polycrystalline metal oxide positive electrode The diameter of the primary grains of the material is less than 1 μm.
The positive electrode material according to any one of claims 12-14, characterized in that the primary crystal grains of the polycrystalline metal oxide positive electrode material grow in disorder on the surface of the inner layer to form the outer layer.
The positive electrode material according to any one of claims 12-14, characterized in that at least part of the primary crystal grains of the polycrystalline metal oxide positive electrode material are radially along the radial direction of the secondary particles of the positive electrode material Growth buildup forms the outer layer on the surface of the inner layer.
The positive electrode material according to any one of claims 12-16, characterized in that the secondary particle size of the positive electrode material is less than or equal to 50 μm.
The positive electrode material according to any one of claims 12-17, characterized in that the single crystal or single crystal-like structure metal oxide positive electrode material of the inner layer and the polycrystalline metal oxide positive electrode material of the outer layer The materials are metal oxide cathode materials for lithium ion batteries, metal oxide cathode materials for sodium ion batteries, metal oxide cathode materials for potassium ion batteries or metal oxide cathode materials for magnesium ion batteries with the same or different compositions.
The positive electrode material according to claim 18, wherein the lithium ion battery metal oxide positive electrode material comprises lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium titanium oxide, lithium iron phosphorus oxide , one or more of lithium nickel cobalt oxide, lithium nickel manganese oxide, and nickel cobalt multiple oxides.
A method for preparing a positive electrode material, comprising the following steps:

Mix the positive electrode material precursor according to any one of claims 1-10 or the positive electrode material precursor prepared by the preparation method according to claim 11 with a metal salt, and obtain a positive electrode material after sintering, and the positive electrode material includes an inner layer and an outer layer located on the surface of the inner layer, the inner layer is a metal oxide positive electrode material with a single crystal or similar single crystal structure, and the outer layer is a metal oxide positive electrode material with a polycrystalline structure.
The preparation method according to claim 20, characterized in that, the sintering temperature is 600°C-800°C, the sintering time is 8-20 hours, and the sintering atmosphere is an oxygen atmosphere.
The preparation method according to claim 20 or 21, wherein the metal salt comprises lithium salt, sodium salt, potassium salt or magnesium salt.
A positive electrode sheet, characterized in that the positive electrode sheet comprises the positive electrode material according to any one of claims 12-19.
A battery, characterized in that the battery comprises a positive electrode sheet, a negative electrode sheet, and an electrolyte and a diaphragm between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet includes the positive electrode sheet according to claim 23.
An electronic device, characterized in that the electronic device comprises the battery according to claim 24.
An energy storage system, characterized in that the energy storage system comprises the battery as claimed in claim 24.