Cathode material, preparation method and application thereof

Abstract

The application provides a positive electrode material and a preparation method and application thereof, and comprises the following steps: weighing a first mass M1 of coating material and a second mass M2 of core material, mixing the weighed core material and coating material, activating the mixture at a first preset temperature, and then sintering at a second preset temperature to obtain the positive electrode material; wherein M1 / M2 satisfies: M1 / M2={[A×(D50 particle size of the coating material / D10 particle size of the core material)]+[B×(D50 particle size of the coating material / D50 particle size of the core material)]+[C×(D50 particle size of the coating material / D90 particle size of the core material)]}×[1+second preset temperature / (D×first preset temperature)] / K. The positive electrode material prepared by the preparation method has a good coating effect, and the interface stability and energy density of the positive electrode material are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the development of the new energy industry, the requirement for the battery endurance is higher and higher, so the battery needs to have higher energy density. By increasing the charging upper limit voltage of the positive electrode material, the reversible capacity and voltage platform of the positive electrode material can be improved, so as to achieve the purpose of improving the energy density. However, with the increase of the voltage, the stability of the positive electrode material will decrease. By coating the positive electrode material, the interface stability of the positive electrode material can be improved, so as to improve the cycle stability of the battery. However, in the related art, the coating effect of the positive electrode material is poor, the agglomeration phenomenon is more, the reaction activity is low, the specific surface area is small, it is difficult to obtain ideal interface stability, and the impedance of the positive electrode material is easily increased. Therefore, a preparation method of the positive electrode material capable of improving the coating effect is needed to obtain the positive electrode material with high interface stability and low impedance, which is beneficial to improving the energy density of the positive electrode material. SUMMARY

[0003] In view of this, the present application provides a positive electrode material and a preparation method and application thereof. In the preparation of the positive electrode material, the coating material and the core material are weighed according to a specific relationship formula constructed by the particle size of the core material, the particle size of the coating material, the preset activation temperature and the sintering temperature, so as to control the mass ratio of the coating material and the core material in a suitable range, which is beneficial to improving the coating effect of the positive electrode material, so as to obtain the positive electrode material with high interface stability and low impedance, which is beneficial to improving the energy density of the positive electrode material.

[0004] In the first aspect, the present application provides a preparation method of a positive electrode material. A first mass M1 of coating material and a second mass M2 of core material are weighed. The weighed core material and coating material are mixed, activated at a first preset temperature, and then sintered at a second preset temperature to obtain a positive electrode material. The ratio M1 / M2 of the first mass M1 to the second mass M2 satisfies: M1 / M2={[A×(D50 particle size of coating material / D10 particle size of core material)]+[B×(D50 particle size of coating material / D50 particle size of core material)]+[C×(D50 particle size of coating material / D90 particle size of core material)]}×[1+second preset temperature / (D×first preset temperature)] / K, 0.01≤A≤0.1, 0.001≤B≤0.09, 0.002≤C≤0.1, 20≤D≤100, 0.5≤K≤1. The first preset temperature is in the range of 800-850℃, and the second preset temperature is in the range of 850-900℃.

[0005] Optionally, the D50 particle size of the coating material is 0.01 μm-20 μm, and the D50 particle size of the core material is 0.05 μm-100 μm.

[0006] Optionally, the D10 particle size of the core material is 0.01 μm-10 μm, and the D90 particle size of the core material is 0.05 μm-500 μm.

[0007] Optionally, the D50 particle size of the coating material is less than the D50 particle size of the core material.

[0008] Optionally, the difference between the D99 particle size of the coating material and the D50 particle size of the coating material is 100 nm-5000 nm.

[0009] Optionally, the difference between the D99 particle size of the coating material and the D10 particle size of the coating material is 300 nm-3000 nm.

[0010] Optionally, the coating material comprises one or more of titanium aluminum lithium phosphate, germanium aluminum lithium phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, zirconium aluminum lithium phosphate, zirconium lithium phosphate, lithium molybdate, lithium niobate, lithium phosphate, aluminum lithium phosphate, fluorine aluminum lithium phosphate, lithium tantalate, titanium lithium phosphate, aluminum lithium silicate, lithium nickel manganese acid, iridium phosphate, cobalt lithium phosphate, cobalt aluminum lithium phosphate, vanadium aluminum lithium phosphate, and vanadium manganese lithium phosphate.

[0011] Optionally, the chemical formula of the core material is Li a Mn b Ni c Co d Al e O2, wherein a≥1; b+c+d=1 and e=0, or c+d+e=1 and b=0, or b+c+d+e=1, and c≥33.

[0012] Optionally, the mixing method comprises one or more of spray drying, solid phase grinding, solid phase mixing, and fluidized bed mixing.

[0013] Optionally, the sintering atmosphere comprises one or more of oxygen, nitrogen, and argon.

[0014] The preparation method of the positive electrode material provided in the present application weighs the coating material and the core material according to a specific relationship formula constructed by the particle size of the core material, the particle size of the coating material, the preset activation temperature, and the sintering temperature, so as to control the mass ratio of the coating material and the core material within a suitable range, which is conducive to improving the coating effect of the positive electrode material, improving the interface stability of the positive electrode material, and further improving the energy density of the positive electrode material.

[0015] In a second aspect, the application provides a positive electrode material, which is prepared by the preparation method of the first aspect.

[0016] Optionally, the positive electrode material comprises a core and a coating layer coated on the surface of the core; the core comprises the core material, and the coating layer comprises the coating material; in the positive electrode material, the mass percentage of the coating layer is 0.1%-10%.

[0017] Optionally, the particle size of the positive electrode material is D50 of 0.05 μm-100 μm.

[0018] Optionally, the specific surface area of the positive electrode material is 0.1 m 2 / g-20 m 2 / g.

[0019] The positive electrode material provided by the application has excellent coating effect, high energy density and good interface stability.

[0020] In a third aspect, the application provides a positive electrode sheet, which comprises a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector; the positive electrode active material layer comprises the positive electrode material prepared by the preparation method of the first aspect or the positive electrode material of the second aspect.

[0021] The positive electrode sheet provided by the application has high specific capacity, good structural stability and long service life.

[0022] In a fourth aspect, the application provides a battery, which comprises a negative electrode sheet and the positive electrode sheet of the third aspect.

[0023] The battery provided by the application has good cycle stability and high reliability, which is conducive to improving the product competitiveness of the battery.

[0024] In a fifth aspect, the application provides an electric device, which comprises the battery of the fourth aspect.

[0025] The electric device provided by the application has excellent safety performance and good electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. The specific embodiments described herein are only used to explain the application and not used to limit the application.

[0027] Figure 1 A cross-sectional structure schematic diagram of the positive electrode material provided by an embodiment of the application;

[0028] Figure 2A scanning electron microscope image of the positive electrode material prepared in Example 1 of the present application;

[0029] Figure 3 A scanning electron microscope image of the positive electrode material prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] The present application provides a preparation method of a positive electrode material, comprising: weighing a first mass M1 of a coating material and a second mass M2 of a core material, mixing the weighed core material and coating material, activating the mixture at a first preset temperature, and then sintering at a second preset temperature to obtain the positive electrode material; wherein the ratio M1 / M2 of the first mass M1 to the second mass M2 satisfies: M1 / M2={[A×(D50 particle size of the coating material / D10 particle size of the core material)]+[B×(D50 particle size of the coating material / D50 particle size of the core material)]+[C×(D50 particle size of the coating material / D90 particle size of the core material)]}×[1+second preset temperature / (D×first preset temperature)] / K, 0.01≤A≤0.1, 0.001≤B≤0.09, 0.002≤C≤0.1, 20≤D≤100, 0.5≤K≤1; the first preset temperature is in the range of 800-850℃, and the second preset temperature is in the range of 850-900℃. The preparation method of the positive electrode material provided by the present application weighs the coating material and the core material according to a specific relationship formula constructed by the particle size of the core material, the particle size of the coating material, the preset activation temperature and the sintering temperature, so as to control the mass ratio of the coating material and the core material within a suitable range, which is conducive to improving the coating effect of the positive electrode material, and a coating layer with suitable thickness and / or coating mode can obtain a positive electrode material with high interface stability and low impedance, which is conducive to improving the rate performance and energy density of the positive electrode material.

[0032] In an embodiment of the present application, the coating material forms a coating layer on the surface of the core. Specifically, the coating material can include, but is not limited to, one or more of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium zirconium aluminum phosphate, lithium zirconium phosphate, lithium molybdate, lithium niobate, lithium phosphate, lithium aluminum phosphate, lithium fluorine aluminum phosphate, lithium tantalate, lithium titanium phosphate, lithium aluminum silicate, lithium nickel manganese acid, iridium phosphate, lithium cobalt phosphate, lithium cobalt aluminum phosphate, lithium vanadium aluminum phosphate and lithium vanadium manganese phosphate. In an embodiment of the present application, the coating material can be lithium phosphate. In another embodiment of the present application, the coating material can be lithium nickel manganese acid.

[0033] In an embodiment of the present application, the D50 particle size of the coating material is 0.01-20 μm. The appropriate D50 particle size of the coating material can improve the coating effect, and improve the energy density and interface stability of the positive electrode material. Specifically, the D50 particle size of the coating material can be, but is not limited to, 0.01 μm, 1 μm, 2 μm, 5 μm, 8 μm, 0.01 μm, 10 μm, 15 μm or 20 μm, etc. In an embodiment of the present application, the D50 particle size of the coating material can be 0.01-10 μm. In another embodiment of the present application, the D50 particle size of the coating material can be 8-20 μm.

[0034] In an embodiment of the present application, the difference between the D99 particle size of the coating material and the D50 particle size of the coating material is 100-5000 nm, which controls the overall particle size distribution of the coating material, improves the matching degree of the particle size distribution of the coating material and the core material, improves the coating effect of the coating material on the core material, avoids the formation of voids, and is conducive to forming a uniform, dense and thin coating layer on the surface of the core. In turn, the low impedance and interface stability of the positive electrode material can be better balanced, and the energy density of the positive electrode material can be improved. Specifically, the difference between the D99 particle size of the coating material and the D50 particle size of the coating material can be, but is not limited to, 100 nm, 150 nm, 200 nm, 500 nm, 1200 nm, 2000 nm, 3000 nm, 4000 nm or 5000 nm, etc. In an embodiment of the present application, the difference between the D99 particle size of the coating material and the D50 particle size of the coating material is 100-2000 nm, which can further promote the coating of the coating material on the core material and improve the coating effect.

[0035] In an embodiment of the present application, the difference between the D99 particle size of the coating material and the D10 particle size of the coating material is 300-3000 nm, which controls the overall particle size distribution of the coating material, improves the matching degree of the particle size distribution of the coating material and the core material, improves the coating effect of the coating material on the core material, avoids the formation of voids, and is conducive to forming a uniform, dense and thin coating layer on the surface of the core. Specifically, the difference between the D99 particle size of the coating material and the D10 particle size of the coating material can be, but is not limited to, 300 nm, 500 nm, 800 nm, 1000 nm, 1500 nm, 2000 nm, 2500 nm or 3000 nm, etc. In an embodiment of the present application, the difference between the D99 particle size of the coating material and the D10 particle size of the coating material can be 300-1500 nm, which can further improve the coating effect of the positive electrode material and improve the electrochemical performance of the positive electrode material.

[0036] In an embodiment of the present application, the chemical formula of the core material is Li a Mn b Nic Co d Al e O2, wherein a≥1; b+c+d=1 and e=0, or c+d+e=1 and b=0, or b+c+d+e=1 and c≥33. In an embodiment of the present application, when a≥1, b+c+d=1 and e=0, the chemical formula of the core material can be Li a Mn b Ni c Co d O2, wherein a can be 1, b can be 0.2, c can be 0.3, d can be 0.5, and the core material can be LiMn 0.2 Ni 0.3 Co 0.5 O2. In another embodiment of the present application, when a≥1, c+d+e=1 and b=0, the chemical formula of the core material can be Li a Ni c Co d Al e O2, wherein a can be 1, c can be 0.2, d can be 0.4, and e can be 0.4, and the core material can be LiNi 0.2 Co 0.4 Al 0.4 O2. In another embodiment of the present application, a≥1, b+c+d+e=1 and c≥33, the chemical formula of the core material can be Li a Mn b Ni c Co d Al e O2, wherein a can be 1, b can be 0.1, c can be 0.7, d can be 0.1, and e can be 0.1, and the core material can be LiMn 0.1 Ni 0.7 Co 0.1 Al 0.1 O2.

[0037] In an embodiment of the present application, the D90 particle size of the core material is 0.05 μm-500 μm. The suitable D90 particle size of the core material can improve the coating effect and improve the energy density and interface stability of the positive electrode material. Specifically, the D90 particle size of the core material can be, but is not limited to, 0.05 μm, 50 μm, 100 μm, 200 μm, 300 μm, 350 μm, 400 μm or 500 μm, etc. In an embodiment of the present application, the D90 particle size of the core material can be 0.05 μm-150 μm. In another embodiment of the present application, the D90 particle size of the core material can be 100 μm-500 μm.

[0038] In an embodiment of the present application, the D50 particle size of the core material is 0.05 μm-100 μm. The appropriate D50 particle size of the core material can improve the coating effect and improve the energy density and interface stability of the positive electrode material. Specifically, the D50 particle size of the core material can be, but is not limited to, 0.05 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 90 μm or 100 μm, etc. In an embodiment of the present application, the D50 particle size of the core material can be 0.05 μm-20 μm. In another embodiment of the present application, the D50 particle size of the core material can be 20 μm-100 μm.

[0039] In an embodiment of the present application, the D50 particle size of the coating material is greater than the D50 particle size of the core material, which is beneficial to form a uniform and thin coating layer on the surface of the core, avoid the occurrence of uneven and peeling of the coating layer, improve the coating effect of the coating material, and improve the electrochemical performance of the positive electrode material.

[0040] In an embodiment of the present application, the D10 particle size of the core material is 0.01 μm-10 μm. Specifically, the D50 particle size of the coating material can be, but is not limited to, 0.01 μm, 1 μm, 2 μm, 5 μm, 8 μm, 0.01 μm, 10 μm, 15 μm or 20 μm, etc. In an embodiment of the present application, the D50 particle size of the coating material can be 0.01 μm-10 μm. In another embodiment of the present application, the D50 particle size of the coating material can be 8 μm-20 μm.

[0041] In an embodiment of the present application, A is a proportional coefficient of the ratio between the D50 particle size of the coating material and the D10 particle size of the core material, 0.01≤A≤0.1, and specifically, the value of A can be, but is not limited to, 0.01, 0.02, 0.04, 0.06, 0.08 or 0.1, etc. In an embodiment of the present application, the value of A can be 0.01-0.06. In another embodiment of the present application, the value of A can be 0.04-0.1. The D50 particle size of the coating material and the D10 particle size of the core material are in the same unit.

[0042] In an embodiment of the present application, B is a proportional coefficient of the ratio between the D50 particle size of the coating material and the D50 particle size of the core material, 0.001≤B≤0.09. Specifically, the value of B can be, but is not limited to, 0.001, 0.002, 0.008, 0.01, 0.02, 0.04, 0.06 or 0.09, etc. In an embodiment of the present application, the value of B can be 0.001-0.04. In another embodiment of the present application, the value of B can be 0.03-0.09. The D50 particle size of the coating material and the D50 particle size of the core material are in the same unit.

[0043] In an embodiment of the present application, C is a proportional coefficient of the ratio between the D50 particle size of the coating material and the D90 particle size of the core material, and 0.002≤C≤0.1. Specifically, the value of C can be, but is not limited to, 0.002, 0.005, 0.008, 0.01, 0.02, 0.04, 0.06, 0.08, or 0.1, etc. In an embodiment of the present application, the value of C can be 0.002-0.08. In another embodiment of the present application, the value of C can be 0.07-0.1. The D50 particle size of the coating material and the D90 particle size of the core material are in the same unit.

[0044] In an embodiment of the present application, the first preset temperature is 800-850°C, and activating the coating material at the first preset temperature can promote the uniform combination of the coating material on the surface of the core material in the subsequent process, thereby improving the coating effect. Specifically, the first preset temperature can be, but is not limited to, 800°C, 810°C, 820°C, 830°C, 840°C, or 850°C, etc. In an embodiment of the present application, the first preset temperature can be 800-830°C. In another embodiment of the present application, the first preset temperature can be 825-850°C.

[0045] In an embodiment of the present application, the second preset temperature is 850-900°C, and the second preset temperature can make the coating material firmly coat and combine on the surface of the core material to form a coating layer, which is conducive to improving the stability of the positive electrode material. Specifically, the second preset temperature can be, but is not limited to, 850°C, 860°C, 870°C, 880°C, 890°C, or 900°C, etc. In an embodiment of the present application, the second preset temperature can be 850-870°C. In another embodiment of the present application, the second preset temperature can be 865-900°C.

[0046] In an embodiment of the present application, D is an optimization parameter of the first preset temperature and the second preset temperature, and 20≤D≤100. Specifically, the value of D can be, but is not limited to, 20, 40, 50, 60, 80, or 100, etc.

[0047] In an embodiment of the present application, K is a correction parameter of the usage amount of the coating material, and 0.5≤K≤1. Since the coating material will be lost and failed during the sintering process, it is necessary to correct the usage amount of the coating material by the correction value K to improve the coating efficiency of the coating material. Specifically, the value of K can be, but is not limited to, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc. In an embodiment of the present application, the value of K can be 0.5-0.8. In another embodiment of the present application, the value of K can be 0.7-1.

[0048] In an embodiment of the present application, the mixing method of the coating material and the core material can include, but is not limited to, one or more of spray drying, solid phase grinding, solid phase mixing, and fluidized bed mixing, which can facilitate uniform mixing of the coating material and the core material and improve the coating effect of the coating material. In an embodiment of the present application, the mixing method can be spray drying. In another embodiment of the present application, the mixing method can be solid phase grinding.

[0049] In an embodiment of the present application, the sintering atmosphere can include, but is not limited to, one or more of oxygen, nitrogen, and argon. In an embodiment of the present application, the sintering atmosphere can be oxygen.

[0050] The present application also provides a positive electrode material prepared by the preparation method of any one of the above embodiments. The positive electrode material provided by the present application has high interface stability and excellent energy density, and can improve the specific capacity and electrochemical performance of the positive electrode sheet.

[0051] Please refer to Figure 1 FIG. 1 is a schematic diagram of the cross-sectional structure of the positive electrode material provided by an embodiment of the present application. The positive electrode material 100 includes a core 10 and a coating layer 20 coated on the surface of the core 10. The core 10 includes a core material, and the core 10 is obtained by sintering the core material. The coating layer 20 includes a coating material, and the coating layer 20 is obtained by sintering the coating material.

[0052] In an embodiment of the present application, the mass percentage of the coating layer in the positive electrode material is 0.1%-10%. An appropriate amount of the coating layer can maintain the excellent energy density of the positive electrode material, improve the coating effect of the positive electrode material, and improve the interface stability of the positive electrode material. Specifically, the mass percentage of the coating layer in the positive electrode material can be, but is not limited to, 0.1%, 1%, 2%, 4%, 6%, 8%, or 10%, etc. In an embodiment of the present application, the mass percentage of the coating layer in the positive electrode material can be 0.1%-5%. In another embodiment of the present application, the mass percentage of the coating layer in the positive electrode material can be 3%-10%.

[0053] In an embodiment of the present application, the coating method of the coating layer can be point-like coating or / and island-like coating. Point-like coating refers to that the coating material is distributed in a granular form on the surface of the core to form the coating layer after sintering. Island-like coating refers to that the coating material is coated on the surface of the core in an agglomerated state to form the coating layer after sintering.

[0054] In an embodiment of the present application, the particle size D50 of the positive electrode material is 0.05 μm-100 μm. The D50 particle size of the suitable positive electrode material can improve the energy density and cycle stability of the battery. Specifically, the D50 particle size of the positive electrode material can be, but is not limited to, 0.05 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 90 μm or 100 μm, etc. In an embodiment of the present application, the D50 particle size of the positive electrode material can be 0.05 μm-20 μm. In another embodiment of the present application, the D50 particle size of the positive electrode material can be 20 μm-100 μm.

[0055] In an embodiment of the present application, the specific surface area of the positive electrode material is 0.1 m 2 / g-20 m 2 / g. The suitable specific surface area can improve the compaction density of the positive electrode sheet and improve the capacity density of the battery. Specifically, the specific surface area of the positive electrode material can be, but is not limited to, 0.1 m 2 / g, 1 m 2 / g, 5 m 2 / g, 8 m 2 / g, 10 m 2 / g, 12 m 2 / g, 15 m 2 / g or 20 m 2 / g, etc. In an embodiment of the present application, the specific surface area of the positive electrode material can be 0.1 m 2 / g-10 m 2 / g. In another embodiment of the present application, the specific surface area of the positive electrode material is 10 m 2 / g-20 m 2 / g.

[0056] The present application provides a positive electrode sheet, which comprises a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode material of any one of the embodiments described above. The positive electrode material provided by the present application has good coating effect, high specific capacity, large specific surface area and high reaction activity, which is beneficial to improve the energy density and electrochemical performance of the positive electrode sheet.

[0057] In an embodiment of the present application, the positive electrode current collector has good electrical conductivity and high electrochemical stability, which can improve the electrochemical stability of the positive electrode sheet. Specifically, the positive electrode current collector can be, but is not limited to, one of nickel, titanium, aluminum, stainless steel, aluminum with carbon or nickel coating and stainless steel with carbon or nickel coating. In an embodiment of the present application, the positive electrode current collector can be an aluminum foil. In some embodiments, the surface of the positive electrode current collector is rough or net-shaped, which can improve the bonding strength between the positive electrode active material layer and the positive electrode current collector. In some embodiments, the shape of the positive electrode current collector can be one or more of film, sheet, foil, net and porous body.

[0058] In an embodiment of the present application, the thickness of the positive current collector is 1-500 μm, specifically, the thickness of the positive current collector can be but is not limited to 1 μm, 10 μm, 100 μm, 200 μm, 300 μm, 400 μm or 500 μm, etc. In an embodiment of the present application, the thickness of the positive current collector can be 1-300 μm. In another embodiment of the present application, the thickness of the positive current collector can be 250-500 μm.

[0059] In an embodiment of the present application, the positive active material layer further comprises a positive binder and a positive conductive agent, which can improve the structural stability and electrochemical performance of the positive electrode sheet.

[0060] In an embodiment of the present application, the positive binder can improve the structural stability of the positive electrode sheet, which is conducive to improving the cycle life of the positive electrode sheet. Specifically, the positive binder can be but is not limited to one or more of polyvinylidene fluoride, fluorovinyl-hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, polyacrylic acid, polyethylene oxide polytetrafluoroethylene and hydrogenated butyl nitrile rubber. In an embodiment of the present application, the positive binder can be polyvinylidene fluoride.

[0061] In an embodiment of the present application, the weight average molecular weight of the positive binder is 50000-500000, which can improve the stability and uniformity of the positive electrode sheet. Specifically, the weight average molecular weight of the positive binder can be but is not limited to 50000, 100000, 200000, 300000, 400000 or 500000, etc. In an embodiment of the present application, the weight average molecular weight of the positive binder can be 50000-300000. In another embodiment of the present application, the weight average molecular weight of the positive binder can be 250000-500000.

[0062] In an embodiment of the present application, the positive conductive agent can improve the conductivity of the positive electrode sheet. Specifically, the positive conductive agent can be but is not limited to one or more of acetylene black, conductive carbon black, graphene and carbon nanotube. In an embodiment of the present application, the positive conductive agent can be acetylene black.

[0063] The present application also provides a battery comprising the positive electrode sheet of any one of the above embodiments, which can improve the service life and electrochemical performance of the battery.

[0064] In an embodiment of the present application, the battery further comprises a negative electrode sheet, which comprises a negative current collector and a negative active layer arranged on the surface of the negative current collector. Specifically, the negative current collector can be but is not limited to one or more of copper, aluminum, nickel and stainless steel. In an embodiment of the present application, the negative current collector can be a copper foil.

[0065] In an embodiment of the present application, the negative active layer comprises a negative active material, which can include, but is not limited to, one or more of silicon, tin, germanium, lithium and alloys thereof, and carbon materials. The carbon materials can include, but are not limited to, one or more of non-graphitized carbon, graphite, pyrolytic carbon, coke and activated carbon. In an embodiment of the present application, the negative active material can be carbon materials. In another embodiment of the present application, the negative active material can be silicon alloys (alloy materials formed by one or more of Si and Ti, Fe, Co, Ni, Cu).

[0066] In an embodiment of the present application, the negative active layer further comprises a negative conductive agent. The negative conductive agent can increase the conductivity between the active materials and improve the electronic conductivity. Specifically, the negative conductive agent can include, but is not limited to, one or more of acetylene black, conductive carbon black, graphene and carbon nanotubes. In an embodiment of the present application, the negative conductive agent can be graphite. In another embodiment of the present application, the negative conductive agent can be carbon black.

[0067] In an embodiment of the present application, the negative active layer further comprises a negative binder. The negative binder can improve the binding ability of the components in the negative active layer and the binding ability between the negative active layer and the negative current collector. Specifically, the negative binder can include, but is not limited to, one or more of polyvinylidene fluoride, polyacrylate, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose and styrene butadiene rubber. In an embodiment of the present application, the negative binder can be polyvinylidene fluoride.

[0068] In an embodiment of the present application, the battery further comprises an electrolyte. At least part of the positive electrode sheet and at least part of the negative electrode sheet are soaked in the electrolyte, and the electrolyte comprises an electrolyte and an organic solvent. Specifically, the electrolyte can include, but is not limited to, one or more of LiPF6, LiBF4, LiCl, LiAlCl4, LiSbF6, LiSCN, LiCF3SO3, LiCF3CO2, LiN(CF3SO2) and LiAsF6, and the organic solvent can include, but is not limited to, one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and vinylene carbonate.

[0069] In the present application, the battery further comprises a separator. The separator can exchange ions and form a complete ion conduction path. Specifically, the separator can include, but is not limited to, woven membranes, non-woven fabrics, microporous membranes, composite membranes, rolled membranes or separator papers, and the material of the separator can include, but is not limited to, polyethylene, polypropylene, polyvinylidene fluoride and composite membranes.

[0070] The application further provides a power-using device, which comprises the battery described in any one of the above embodiments. The power-using device provided by the application has high energy density, good cycle performance and high safety performance. The power-using device includes a vehicle, an electronic device, an energy storage system and the like, wherein the electronic device may be, for example, a mobile phone, a tablet, a watch, a VR glasses and the like. In an embodiment of the application, the battery can be used in a vehicle, so as to improve the service life and cycle performance of the vehicle, improve the wide application of new energy vehicles and be conducive to the construction of a green and environmentally-friendly environment. In another embodiment of the application, the battery can also be applied to a mobile phone, so as to reduce the preparation cost of the battery and improve the use safety of the battery. The above battery of the application can be arranged in a power-using device in the form of a single battery, a battery module, a battery pack and the like.

[0071] The effects of the technical solutions of the application are further described below through specific examples.

[0072] Embodiment 1

[0073] The preparation method of the positive electrode material comprises:

[0074] (1) selecting a core material (lithium cobaltate) and a coating material (nano lithium titanium aluminum phosphate), wherein the D50 particle size of the coating material is 412 nm, the D90 particle size of the core material is 27168 nm, the D50 particle size of the core material is 16360 nm, the D10 particle size of the core material is 5190 nm, the first preset temperature is 850 DEG C, the second preset temperature is 850 DEG C, A is 0.01, B is 0.001, C is 0.002, D is 100, K is 1, and the ratio M1 / M2 of the mass M1 of the coating material to the mass M2 of the core material is calculated according to the relationship M1 / M2={[A×(D50 particle size of coating material / D10 particle size of core material)]+[B×(D50 particle size of coating material / D50 particle size of core material)]+[C×(D50 particle size of coating material / D90 particle size of core material)]}×[1+second preset temperature / (D×first preset temperature)] / K, and the ratio M1 / M2 of the mass M1 of the coating material to the mass M2 of the core material is 0.000858;

[0075] (2) according to M1 / M2=0.000858, 0.429g of the coating material and 500g of the core material are weighed, the above core material and coating material are loaded into a 1.0L ball mill jar, 500g of large, medium and small zirconium beads are added, the cover is covered, and the jar mill is placed on the ball mill for 6h, then the uniformly mixed coating material and core material are loaded into a sagger, and the sagger is placed in a muffle furnace, activated at the first preset temperature for 2h, and sintered at the second preset temperature for 8h, to obtain the positive electrode material.

[0076] Embodiment 2

[0077] The difference from example 1 is that the first preset temperature is set to 800 DEG C, the second preset temperature is set to 900 DEG C, A is 0.1, B is 0.09, C is 0.1, D is 20, K is 0.5, and M1 / M2 is calculated to be 0.0248; according to M1 / M2=0.0248, 12.381g of coating material and 500g of core material are weighed.

[0078] Example 3

[0079] The difference from example 1 is that the first preset temperature is set to 820 DEG C, the second preset temperature is set to 870 DEG C, A is 0.013, B is 0.009, C is 0.0041, D is 20, K is 0.67, and M1 / M2 is calculated to be 0.00208; according to M1 / M2=0.00208, 1.038g of coating material and 500g of core material are weighed.

[0080] Example 4

[0081] The difference from example 1 is that the first preset temperature is set to 850 DEG C, the second preset temperature is set to 900 DEG C, A is 0.013, B is 0.009, C is 0.0041, D is 79, K is 0.67, and M1 / M2 is calculated to be 0.00200; according to M1 / M2=0.00200, 0.999g of coating material and 500g of core material are weighed.

[0082] Example 5

[0083] The difference from example 1 is that the D50 particle size of the coating material is 48nm, the D90 particle size of the core material is 26186nm, the D50 particle size of the core material is 16986nm, the D10 particle size of the core material is 4972nm, M1 / M2 is calculated to be 0.000104, and according to M1 / M2=0.000104, 0.052g of coating material and 500g of core material are weighed.

[0084] Example 6

[0085] The difference from example 1 is that the D50 particle size of the coating material is 48nm, the D90 particle size of the core material is 26186nm, the D50 particle size of the core material is 16986nm, the D10 particle size of the core material is 4972nm, the first preset temperature is set to 800 DEG C, and the second preset temperature is set to 900 DEG C; A is 0.1, B is 0.09, C is 0.1, D is 20, K is 0.5, and M1 / M2 is calculated to be 0.00296; according to M1 / M2=0.00296, 1.482g of coating material and 500g of core material are weighed.

[0086] Example 7

[0087] The difference from Example 1 is that the D50 particle size of the coating material is 2549 nm, A is 0.01, B is 0.001, C is 0.002, D is 100, and K is 1, and M1 / M2 is calculated to be 0.00531. According to M1 / M2 = 0.00531, 2.654 g of coating material and 500 g of core material are weighed.

[0088] Example 8

[0089] The difference from Example 1 is that the D50 particle size of the coating material is 2549 nm, A is 0.1, B is 0.09, C is 0.1, D is 100, and K is 1, and M1 / M2 is calculated to be 0.0732. According to M1 / M2 = 0.0732, 36.622 g of coating material and 500 g of core material are weighed.

[0090] Example 9

[0091] The difference from Example 1 is that the D50 particle size of the coating material is 2549 nm, the D90 particle size of the core material is 25481 nm, the D50 particle size of the core material is 14681 nm, the D10 particle size of the core material is 4268 nm, A is 0.01, B is 0.001, C is 0.002, D is 100, and K is 1, and M1 / M2 is calculated to be 0.00641. According to M1 / M2 = 0.00641, 3.205 g of coating material and 500 g of core material are weighed.

[0092] Example 10

[0093] The difference from Example 1 is that the D50 particle size of the coating material is 2549 nm, the D90 particle size of the core material is 25481 nm, the D50 particle size of the core material is 14681 nm, the D10 particle size of the core material is 4268 nm, the first preset temperature is set to 800°C, the second preset temperature is set to 900°C, A is 0.1, B is 0.09, C is 0.1, D is 20, and K is 0.5, and M1 / M2 is calculated to be 0.180. According to M1 / M2 = 0.180, 90.155 g of coating material and 500 g of core material are weighed.

[0094] Comparative Example 1

[0095] The difference from Example 1 is that 0.248 g of coating material and 500 g of core material are weighed, and the mass ratio of the weighed coating material and core material is less than M1 / M2.

[0096] Comparative Example 2

[0097] The difference from Example 2 is that 20 g of the coating material and 500 g of the core material are weighed, and the mass ratio of the coating material to the core material is greater than M1 / M2.

[0098] Performance detection

[0099] The positive electrode material prepared in the above Examples 1-10 and Comparative Examples 1-2 is mixed with a binder and a conductive agent and dissolved in N-methyl pyrrolidone to obtain a positive electrode slurry, wherein the mass ratio of the positive electrode material, the conductive agent and the binder is 100:3:2; the positive electrode slurry is coated on one side of a 16 μm thick positive electrode current collector aluminum foil, and then dried at 85°C for 24 h with air blowing, and vacuum dried after cold pressing to obtain a positive electrode sheet.

[0100] The positive electrode sheet prepared in the above Examples 1-10 and Comparative Examples 1-2, a separator and a negative electrode sheet are laminated to obtain a bare battery cell; the bare battery cell is placed in an outer packaging foil, an electrolyte is injected into the dried battery cell, and then the processes of vacuum packaging, standing, formation, shaping and the like are performed to obtain a battery; wherein the preparation of the negative electrode sheet: a negative electrode active material (artificial graphite), a conductive agent, a binder, a thickening agent are dissolved in a solvent (deionized water) according to a mass ratio of 97:1:1.5:0.5 to prepare a negative electrode slurry, which is coated on both sides of a negative electrode current collector copper foil, and then dried at 80°C for 20 h with air blowing, and vacuum dried after cold pressing to obtain a negative electrode sheet.

[0101] The batteries prepared in the above Examples 1-10 and Comparative Examples 1-2 are subjected to rate performance testing, and the testing process is as follows: the battery is allowed to stand at 25°C for 5 min, charged at 0.1C constant current to a voltage of 4.60V, then charged at 4.60V constant voltage to a current of 0.05C, allowed to stand for 5 min, and then discharged at 0.1C and 1C constant current to a voltage of 3.0V, respectively, and 4 lithium ion batteries are taken for testing in each group, and the average value is taken; the rate performance of the battery (%) = the second cycle discharge capacity of the battery at 1C / the first cycle discharge capacity of the battery at 0.1C x 100%, and the test results are shown in Table 1.

[0102] The batteries prepared in the above Examples 1-10 and Comparative Examples 1-2 are subjected to low temperature performance testing, and the testing process is as follows: the battery is allowed to stand at 25°C for 5 min, charged at 0.1C constant current to a voltage of 4.60V, then charged at 4.60V constant voltage to a current of 0.05C, allowed to stand for 5 min, and then discharged at 1C constant current to a voltage of 3.0V at minus 20°C, and 4 batteries are taken for testing in each group, and the average value is taken; the low temperature performance of the battery (%) = the discharge capacity of the battery at minus 20°C at 1C / the first cycle discharge capacity of the battery at 0.1C x 100%, and the test results are shown in Table 1.

[0103] The batteries prepared in the above Examples 1-10 and Comparative Examples 1-2 were subjected to high-temperature performance testing, and the testing procedure was as follows: the batteries were allowed to stand at 45°C for 60 min, then charged at 0.5C to a voltage of 4.60V, and then charged at 4.60V to a current of 0.05C, and allowed to stand for 5 min. Then discharged at 0.5C to a voltage of 3.0V, and the cycle was repeated for 50 times, and 4 batteries were taken for testing in each group, and the average value was taken; the high-temperature cycle performance of the battery (%) = the discharge capacity of the battery at 0.5C after 50 cycles / the discharge capacity of the battery at 0.5C in the first cycle x 100%, and the test results are shown in Table 1.

[0104] Figure 2 The scanning electron microscope image of the positive electrode material prepared in Example 1 of the present application, Figure 3 The scanning electron microscope image of the positive electrode material prepared in Comparative Example 1 of the present application. It can be seen that the surface of the positive electrode material of Example 1 is smoother than that of the positive electrode material of Comparative Example 1, indicating that the coating material can be closely combined with the core material, significantly improving the protection of the coating material on the positive electrode material.

[0105] Table 1: Battery performance test results

[0106] Rate performance (%) Low temperature performance (%) High temperature cycle performance (%) Example 1 91 78 80 Example 2 93 81 82 Example 3 89 81 82 Example 4 92 83 81 Example 5 93 76 83 Example 6 94 78 85 Example 7 94 78 79 Example 8 90 75 76 Example 9 93 81 84 Example 10 91 80 82 Comparative Example 1 85 68 71 Comparative Example 2 75 51 70

[0107] According to Examples 1-10 and Comparative Examples 1-2, it can be seen that the positive electrode material provided in the present application has a ratio M1 / M2 of the first mass M1 of the coating layer material to the second mass M2 of the core material that satisfies a specific relationship constructed from the particle size of the core material, the particle size of the coating material, the preset activation temperature and sintering temperature, which improves the uniformity of the coating material, and the battery has excellent rate performance, low-temperature performance and high-temperature cycle performance, which is beneficial to improve the energy density and cycle life of the battery. According to Example 1 and Comparative Example 1, it can be seen that in the present application, the positive electrode material prepared to satisfy the specific relationship can realize the close combination of the coating layer and the core, improve the protection of the coating material on the positive electrode material, and improve the cycle stability of the coating material.

[0108] The above is a preferred embodiment of the present application, but it cannot be construed as limiting the scope of the present application. It should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered within the scope of protection of the present application.

Claims

1. A method for producing a positive electrode material, characterized by, The application relates to a preparation method of a positive electrode material. The first mass M1 of coating material and the second mass M2 of core material are weighed, the weighed core material and coating material are mixed, activated at a first preset temperature, and then sintered at a second preset temperature to obtain the positive electrode material. The ratio M1 / M2 of the first mass M1 to the second mass M2 satisfies the following formula: M1 / M2={[A x (D50 particle size of the coating material / D10 particle size of the core material)]+[B x (D50 particle size of the coating material / D50 particle size of the core material)]+[C x (D50 particle size of the coating material / D90 particle size of the core material)]}x[1+second preset temperature / (D x first preset temperature)] / K, 0.01<=A<=0.1, 0.001<=B<=0.09, 0.002<=C<=0.1, 20<=D<=100, 0.5<=K<=1; the first preset temperature is in the range of 800-850 DEG C, and the second preset temperature is in the range of 850-900 DEG C.

2. The production method according to claim 1, wherein The D50 particle size of the coating material is 0.01-20 microns, the D50 particle size of the core material is 0.05-100 microns, the D10 particle size of the core material is 0.01-10 microns, and the D90 particle size of the core material is 0.05-500 microns.

3. The production method according to claim 1, wherein The D50 particle size of the coating material is smaller than the D50 particle size of the core material.

4. The production method according to claim 1, wherein The difference between the D99 particle size of the coating material and the D50 particle size of the coating material is 100-5000 nanometers, and the difference between the D99 particle size of the coating material and the D10 particle size of the coating material is 300-3000 nanometers.

5. The production method according to claim 1, wherein The coating material comprises one or more of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanium oxide, lithium zirconium aluminum phosphate, lithium zirconium phosphate, lithium molybdate, lithium niobate, lithium phosphate, lithium aluminum phosphate, lithium fluorine aluminum phosphate, lithium tantalate, lithium titanium phosphate, lithium aluminum silicate, lithium nickel manganese acid, iridium phosphate, lithium cobalt phosphate, lithium cobalt aluminum phosphate, lithium vanadium aluminum phosphate and lithium vanadium manganese phosphate.

6. The production method according to claim 1, wherein The chemical formula of the core material is Li a Mn b Ni c Co d Al e O2, Wherein, a>=1; b+c+d=1 and e=0, or c+d+e=1 and b=0, or b+c+d+e=1, and c>=0.

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7. The production method according to claim 1, wherein The mixing mode comprises one or more of spray drying, solid phase grinding, solid phase mixing and fluidized bed mixing. The sintering atmosphere comprises one or more of oxygen, nitrogen and argon.

8. A positive electrode material, characterized by, The positive electrode material is prepared by the preparation method in any one of claims 1-7.

9. The positive electrode material of claim 8, wherein, The positive electrode material comprises a core and a coating layer coated on the surface of the core; the core comprises the core material, and the coating layer comprises the coating material. The mass percentage of the coating layer in the positive electrode material is 0.1%-10%.

10. The positive electrode material of claim 8, wherein, The particle size D50 of the positive electrode material is 0.05 μm-100 μm, the specific surface area of the positive electrode material is 0.1 m 2 / g-20 m 2 / g.

11. A positive electrode sheet characterized by comprising: The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode material prepared by the preparation method in any one of claims 1-7 or the positive electrode material in any one of claims 8-10.

12. A battery, characterized by The battery comprises a negative electrode sheet and the positive electrode sheet in claim 11.

13. An electrical device, characterized by The power utilization device includes the battery of claim 12.

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