Positive electrode active material, positive electrode, battery, and power-driven device

Abstract

The application provides a positive electrode active material, including a ternary positive electrode material and a carbon-nitrogen coating layer covering the ternary positive electrode material, a particle size of a single crystal particle of the ternary positive electrode material is X μm, a mass content of nitrogen in the carbon-nitrogen coating layer is Y, and a liquid retention amount of the positive electrode active material is Q g / cm 3 , wherein the X, the Y and the Q satisfy: -0.05≤Q+0.01(X 2 -100×Y 2 )‑0.026(3X‑10Y)≤0.05. The single crystal particle size, the mass content of nitrogen in the carbon-nitrogen coating layer and the liquid retention amount of the positive electrode active material provided by the application satisfy a certain relationship, which can improve the cycle performance of the positive electrode active material and is beneficial to the use of the positive electrode active material. The application further provides a positive electrode, a battery and an electric device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a positive electrode active material, a positive electrode, a battery and an electric device. BACKGROUND

[0002] A ternary positive electrode material is widely used in batteries due to its high energy density. The performance requirements of batteries are becoming higher and higher, for example, the cycle performance of batteries needs to be improved. However, the cycle performance of the ternary positive electrode material is relatively poor, which cannot meet the requirement of improving the cycle performance of the battery. Therefore, it is necessary to research and develop a new ternary positive electrode material. SUMMARY

[0003] Therefore, the present application provides a positive electrode active material, a positive electrode, a battery and an electric device. The mass content of nitrogen element in the carbon-nitrogen coating layer and the liquid retention amount of the positive electrode active material satisfy a certain relationship, which is beneficial to improve the cycle performance of the positive electrode and the battery, thereby improving the service life of the battery.

[0004] In a first aspect, the present application provides a positive electrode active material, comprising a ternary positive electrode material and a carbon-nitrogen coating layer covering the ternary positive electrode material, wherein the particle size of a single crystal particle of the ternary positive electrode material is X μm, the mass content of nitrogen element in the carbon-nitrogen coating layer is Y, and the liquid retention amount of the positive electrode active material is Q g / cm 3 , wherein the X, the Y and the Q satisfy: -0.05≤Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y)≤0.05.

[0005] Optionally, the X is 1-10.

[0006] Optionally, the Y is 0.01%-50%.

[0007] Optionally, the X is 3.5-4.5, and the Y is 9%-15%.

[0008] Optionally, the Q is greater than or equal to 0.1.

[0009] Optionally, the thickness of the carbon-nitrogen coating layer is less than or equal to 1 μm.

[0010] Optionally, the mass content of carbon element in the positive electrode active material is 0.1%-2%.

[0011] Optionally, the ternary positive electrode material comprises Li α Ni β Co γ M 1-β-γO2, wherein 0.98≤α≤1.02, 0<β<1, 0<γ<1, and M is selected from at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo and Mn.

[0012] Optionally, the form of the nitrogen element in the carbon-nitrogen coating layer includes at least one of pyridine nitrogen, pyrrole nitrogen, graphitized nitrogen and oxidized nitrogen.

[0013] The single crystal particle size, the mass content of the nitrogen element in the carbon-nitrogen coating layer and the liquid retention amount of the positive electrode active material provided in the present application meet certain relationships, thereby helping to improve the cycle performance of the positive electrode active material and being conducive to the use of the positive electrode active material.

[0014] In a second aspect, the present application provides a positive electrode, comprising a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, wherein the positive electrode active material layer comprises the positive electrode active material of the first aspect.

[0015] The positive electrode provided in the present application has excellent cycle performance, and is conducive to the use of the positive electrode.

[0016] In a third aspect, the present application provides a battery, comprising a negative electrode and the positive electrode of the second aspect.

[0017] The battery provided in the present application has good cycle performance and good safety, and is conducive to long-time use.

[0018] In a fourth aspect, the present application provides an electric device, comprising the battery of the third aspect.

[0019] The battery in the electric device provided in the present application has excellent electrochemical performance, thereby improving the use performance and service life of the electric device. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced here. The specific embodiments described here are only used to explain the present application, and are not used to limit the present application.

[0021] Figure 1 A cross-sectional schematic view of the positive electrode active material provided in an embodiment of the present application.

[0022] Figure 2 A cross-sectional view of the positive electrode provided in an embodiment of the present application.

[0023] Figure 3 An electron microscope image of the positive electrode active material prepared in Example 1. DETAILED DESCRIPTION

[0024] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0025] Please refer to Figure 1 , the cross-sectional schematic diagram of the positive electrode active material provided by an embodiment of the present application, wherein the positive electrode active material 10 comprises a ternary positive electrode material 11 and a carbon-nitrogen coating layer 12 coating the ternary positive electrode material 11, the particle size of the single crystal particles of the ternary positive electrode material 11 is X μm, the mass content of nitrogen element in the carbon-nitrogen coating layer 12 is Y, and the liquid retention amount of the positive electrode active material 10 is Q g / cm 3 , X, Y and Q satisfy: -0.05≤Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y)≤0.05.

[0026] The carbon-nitrogen coating layer is used to coat the ternary positive electrode material in the positive electrode active material provided by the present application. Compared with the ternary positive electrode material without coating, the coating of the carbon-nitrogen coating layer can avoid the contact between the electrolyte and the ternary positive electrode material, thereby avoiding the occurrence of side reactions, ensuring the performance of the ternary positive electrode material, and compared with the carbon coating layer, the carbon-nitrogen coating layer can make the originally electrically neutral interface exhibit electronegativity, can produce electrostatic adsorption between the lithium salt with positive electricity in the electrolyte, thereby improving the liquid retention effect of the positive electrode active material, and the setting of the carbon-nitrogen coating layer can further avoid the direct contact between the ternary positive electrode material and the electrolyte, thereby improving the long-term cycle stability of the ternary positive electrode material, and further improving the cycle stability of the positive electrode active material; at the same time, the particle size of the single crystal particles of the ternary positive electrode material, the mass content of nitrogen element in the carbon-nitrogen coating layer and the liquid retention amount of the positive electrode active material satisfy the relationship -0.05≤Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y)≤0.05, which can improve the cycle performance of the positive electrode and the battery, that is, by adjusting the particle size of the single crystal particles of the ternary positive electrode material, the mass content of nitrogen element in the carbon-nitrogen coating layer and the liquid retention amount of the positive electrode active material, the positive electrode and the battery with excellent cycle performance are obtained, which is beneficial to improve the use of the positive electrode and the battery.

[0027] In the present application, the particle size of the single crystal particles of the ternary positive electrode material is X, and the unit is μm. The particle size of the single crystal particles of the ternary positive electrode material is measured by an electron microscope energy spectrometer, and the average value of the particle size of at least 200 single crystal particles of the ternary positive electrode material is taken as X. The carbon-nitrogen coating layer contains carbon and nitrogen elements, and the mass content of nitrogen is Y, that is, the mass content of carbon in the carbon-nitrogen coating layer is not 0, the mass content of nitrogen is not 0 (Y is not 0), and the mass content of carbon and nitrogen in the carbon-nitrogen coating layer is measured by an energy spectrometer. The liquid retention amount of the positive electrode active material is Q, and the unit is g / cm 3 . The positive electrode active material is mixed with a binder and a conductive agent to form a positive electrode slurry; the positive electrode slurry is coated on an aluminum foil current collector to form a positive electrode active material layer (volume V1), and the overall mass is M0 after drying under the condition of 1.5 MPa rolling at 25°C; it is placed in LiPF6 electrolyte (wherein the lithium salt concentration is 1 mol / L, and the solvent is ethylene carbonate and dimethyl carbonate), and the mass M1 is measured after standing for 3 h and taking out, and the liquid retention amount Q is (M1-M0) / V1.

[0028] It can be understood that the ternary positive electrode material in the present application can include single crystal particles, or secondary particles formed by aggregation of single crystal particles. In the present application, the particle size of the single crystal particles of the ternary positive electrode material is X μm. In an embodiment of the present application, X is 1-10. When the particle size of the single crystal particles of the ternary positive electrode material is 1 μm-10 μm, the single crystal particles of the ternary positive electrode material can avoid agglomeration and have a suitable specific surface area, which is helpful to improve the liquid retention capacity of the positive electrode active material, and is also conducive to the deintercalation of lithium, and has low preparation difficulty and preparation cost, which is conducive to the improvement of the performance of the positive electrode active material and the use. Specifically, X can be but is not limited to 1, 1.5, 1.7, 2, 2.2, 2.5, 3, 3.4, 3.5, 3.6, 3.9, 4, 4.2, 4.5, 4.6, 5, 5.5, 5.8, 6, 6.1, 6.5, 7, 7.5, 7.6, 8, 8.3, 8.5, 9, 9.5, 9.9 or 10, etc. In an embodiment of the present application, X can be 1-8. In another embodiment of the present application, X can be 2-8. In still another embodiment of the present application, X can be 3-7. In still another embodiment of the present application, X can be 3-6. In still another embodiment of the present application, X can be 3-5, which is conducive to the preparation of the positive electrode active material, and is conducive to the deintercalation of lithium, and can also improve the liquid retention capacity of the positive electrode active material, and improve the rate performance of the positive electrode and the battery. In still another embodiment of the present application, X can be 3-4.5. In still another embodiment of the present application, X can be 3.5-4.5. When the particle size of the single crystal particles of the ternary positive electrode material is 3.5 μm-4.5 μm, the particle packing effect of the positive electrode material is the best, that is, it has a suitable compaction and liquid retention gap between particles, so that the electrochemical performance of the positive electrode material is the best. In still another embodiment of the present application, X can be 3.5-4.

[0029] In an embodiment of the present application, the ternary positive electrode material includes Li α Ni β Co γ M 1-β-γ O2, wherein 0.98≤α≤1.02, 0<β<1, 0<γ<1, and M is selected from at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo and Mn. The above-mentioned ternary positive electrode material has higher energy density than iron phosphate (LiFePO4), and also meets the service requirement of the life condition of the power battery. Specifically, the ternary positive electrode material can but is not limited to include Li α Ni β Co γ Al 1-β-γ O2, Li α Ni β Co γ Mg 1-β-γ O2, Li α Ni βCo γ Ga 1-β-γ O2, Li α Ni β Co γ Ti 1-β-γ O2, Li α Ni β Co γ Cr 1-β-γ O2, Li α Ni β Co γ Cu 1-β-γ O2, Li α Ni β Co γ Zn 1-β-γ O2, Li α Ni β Co γ Mo 1-β-γ O2 and Li α Ni β Co γ Mn 1-β-γ at least one of O2.

[0030] In the related art, when the positive active material directly uses the ternary positive electrode material, the ternary positive electrode material completely contacts the electrolyte, so that a side reaction occurs between the electrolyte and the ternary positive electrode material, reducing the use performance of the positive active material and affecting the service life of the battery. In the present application, a carbon-nitrogen coating layer is coated on the surface of the ternary positive electrode material, thereby avoiding the ternary positive electrode material from completely contacting the electrolyte during use, thereby reducing or even avoiding the occurrence of side reactions, improving the use performance of the ternary positive electrode material, thereby improving the service life of the positive active material, and more favorably using it in the positive electrode and the battery; at the same time, compared with the carbon coating layer, the carbon-nitrogen coating layer can better improve the liquid retention capacity of the positive active material, thereby improving the cycle performance and service life of the positive electrode and the battery.

[0031] In the present application, the mass content of nitrogen element in the carbon-nitrogen coating layer is Y. In an embodiment of the present application, Y is 0.01% to 50%. When the mass content of nitrogen element in the carbon-nitrogen coating layer is 0.01% to 50%, a strong electrostatic adsorption effect can be generated, which helps to improve the liquid retention capacity of the positive active material, and at the same time improves the coating stability of the carbon-nitrogen coating layer and the structural reliability of the positive active material, thereby helping to improve the performance of the positive electrode and the battery. Specifically, Y can be, but is not limited to, 0.01%, 0.03%, 0.05%, 0.09%, 0.1%, 0.35%, 0.5%, 0.7%, 1%, 5%, 8%, 10%, 12%, 14%, 15%, 19%, 20%, 22%, 25%, 27%, 30%, 31%, 35%, 36%, 40%, 43%, 45%, 47% or 50%, etc. In an embodiment of the present application, Y can be 1% to 45%. In another embodiment of the present application, Y can be 2% to 35%. In yet another embodiment of the present application, Y can be 5% to 30%. In yet another embodiment of the present application, Y can be 5% to 25%. In yet another embodiment of the present application, Y can be 5% to 20%, which is conducive to the long-term and stable coating of the carbon-nitrogen coating layer on the ternary positive electrode material, and also helps to improve the liquid retention capacity of the positive active material, improve the solid-liquid mass transfer efficiency, and improve the cycle performance and service life of the positive electrode and the battery. In yet another embodiment of the present application, Y can be 5% to 15%. In yet another embodiment of the present application, Y can be 9% to 15%, thereby further improving the performance of the positive active material. In yet another embodiment of the present application, Y can be 10% to 15%.

[0032] In an embodiment of the present application, X is 3.5 to 4.5 and Y is 9% to 15%. This is conducive to improving the effective and long-term coating of the carbon-nitrogen coating layer on the ternary positive electrode material, and further improving the liquid retention capacity of the positive active material, thereby further improving the solid-liquid mass transfer efficiency, cycle performance, etc. of the positive electrode and the battery. In an embodiment of the present application, X is 3.5 to 4.5 and Y is 10% to 15%. In another embodiment of the present application, X is 3.5 to 4.2 and Y is 9% to 15%. In yet another embodiment of the present application, X is 3.5 to 4 and Y is 10% to 15%. The above selection further cooperates the ternary positive electrode material and the carbon-nitrogen coating layer, so that the positive active material has a high liquid retention capacity, and further improves the cycle performance of the positive electrode and the battery. In a specific embodiment, X can be 3.9 and Y can be 12%, thereby further improving the cycle performance of the positive electrode and the battery.

[0033] In the present application, the carbon element contained in the carbon-nitrogen coating layer can improve the electron transport capacity of the ternary cathode material, accelerate the deintercalation of lithium ions, and improve the rate performance of the cathode active material. In an embodiment of the present application, the mass content of carbon element in the cathode active material is 0.1% to 2%. The above content can not only ensure the improvement of the rate performance of the cathode active material, but also further increase the content of the ternary cathode material in the cathode active material and improve the electrochemical performance of the cathode active material. Specifically, the mass content of carbon element in the cathode active material can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.5%, 1.8%, 1.9% or 2%, etc. In an embodiment, the mass content of carbon element in the cathode active material can be 0.5% to 2%. In another embodiment, the mass content of carbon element in the cathode active material can be 1% to 2%. In still another embodiment, the mass content of carbon element in the cathode active material can be 1% to 1.5%.

[0034] In an embodiment of the present application, the form of nitrogen element in the carbon-nitrogen coating layer can include at least one of pyridine nitrogen, pyrrole nitrogen, graphitized nitrogen and oxidized nitrogen, thereby ensuring the stable existence of nitrogen in the carbon-nitrogen coating layer. In an embodiment of the present application, the form of carbon element in the carbon-nitrogen coating layer can include at least one of graphene, amorphous carbon, graphite, acetylene black and carbon nanotube. In an embodiment of the present application, the number of layers of graphene can be 1 to 100 layers. Specifically, the number of layers of graphene can be, but is not limited to, 3 to 90 layers, 10 to 80 layers or 15 to 75 layers, etc.

[0035] In an embodiment of the present application, the thickness of the carbon-nitrogen coating layer is less than or equal to 1 μm. The above thickness not only ensures the coating of the carbon-nitrogen coating layer on the ternary cathode material, avoids the contact of the ternary cathode material with the electrolyte, but also ensures the use performance of the ternary cathode material in the cathode active material. Specifically, the thickness of the carbon-nitrogen coating layer can be, but is not limited to, 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1 μm, etc. In an embodiment of the present application, the thickness of the carbon-nitrogen coating layer can be 10 nm to 1 μm. In another embodiment of the present application, the thickness of the carbon-nitrogen coating layer can be 100 nm to 900 nm. In still another embodiment of the present application, the thickness of the carbon-nitrogen coating layer can be 400 nm to 800 nm.

[0036] In an embodiment of the present application, the carbon-nitrogen coating rate of the positive electrode active material can be greater than or equal to 50%. It can be understood that the coating rate is the ratio of the area of the carbon-nitrogen coating layer covering the ternary positive electrode material to the entire surface area of the ternary positive electrode material. Specifically, the carbon-nitrogen coating rate of the positive electrode active material can be, but is not limited to, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%, etc. In an embodiment of the present application, the carbon-nitrogen coating rate of the positive electrode active material can be 50% to 90%. In another embodiment of the present application, the carbon-nitrogen coating rate of the positive electrode active material can be 60% to 80%.

[0037] In the present application, the carbon-nitrogen coating layer can be a non-porous structure or a porous structure. In an embodiment of the present application, the carbon-nitrogen coating layer has a pore structure, which can include at least one of micropores and mesopores. Among them, the pore structure with a pore size less than 2 nm is micropore, and the pore structure with a pore size of 2 nm to 50 nm is mesopore.

[0038] In an embodiment of the present application, the carbon-nitrogen coating layer can also contain oxygen elements. Specifically, the content of oxygen elements in the carbon-nitrogen coating layer can be, but is not limited to, less than or equal to 0.05%, 0.1%, 0.5%, 0.8%, 1%, 2%, or 3%, etc. In another embodiment of the present application, the sum of the mass content of carbon elements and nitrogen elements in the carbon-nitrogen coating layer is 1. That is, the carbon-nitrogen coating layer does not contain other impurity elements.

[0039] In the present application, the particle size X of the single crystal particles of the ternary positive electrode material, the mass content Y of nitrogen elements in the carbon-nitrogen coating layer, and the liquid retention Q of the positive electrode active material satisfy the relationship -0.05≤Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y)≤0.05, which can improve the cycle performance of the positive electrode and the battery; wherein the liquid retention of the positive electrode active material can be selected as needed. In an embodiment of the present application, the liquid retention of the positive electrode active material can be greater than 0.07 g / cm 3 , that is, Q is greater than 0.07. In another embodiment of the present application, the liquid retention of the positive electrode active material can be greater than 0.11 g / cm 3 , that is, Q is greater than 0.11, the positive electrode active material has a higher liquid retention capacity, which is beneficial to improve the use performance of the positive electrode active material and the battery. In yet another embodiment of the present application, the liquid retention of the positive electrode active material can be greater than or equal to 0.13 g / cm 3 , which is beneficial to improve the energy density of the positive electrode and the battery, and improve the use performance of the positive electrode and the battery. Specifically, the liquid retention of the positive electrode active material can be, but is not limited to, greater than or equal to 0.13 g / cm 3 , greater than or equal to 0.14 g / cm 3greater than or equal to 0.15 g / cm 3 greater than or equal to 0.155 g / cm 3 or greater than or equal to 0.16 g / cm 3 and so on. In an embodiment of the present application, the liquid retention amount of the positive electrode active material can be greater than 0.07 g / cm 3 and less than 0.25 g / cm 3 . In an embodiment, the liquid retention amount of the positive electrode active material can be greater than 0.11 g / cm 3 and less than 0.2 g / cm 3 , which is beneficial to improve the liquid retention capacity of the positive electrode active material, while not excessively increasing the preparation difficulty of the positive electrode and the battery, and is helpful to improve the use performance of the positive electrode and the battery. In another embodiment, the liquid retention amount of the positive electrode active material can be greater than 0.11 g / cm 3 and less than 0.18 g / cm 3 .

[0040] The present application also provides a preparation method of the positive electrode active material, which comprises mixing the ternary positive electrode material with a carbon source and a nitrogen source, and forming a carbon-nitrogen coating layer on the surface of the ternary positive electrode material after heating to obtain the positive electrode active material in any of the above embodiments.

[0041] In an embodiment of the present application, the lithium source, the nickel source, the cobalt source and the raw material containing M element can be mixed and reacted to obtain the ternary positive electrode material. M is selected from at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo and Mn. Specifically, the lithium source can include at least one of lithium hydroxide, lithium chloride, lithium bromide, lithium sulfate, lithium nitrate, lithium chlorate, lithium formate and lithium acetate, such as LiOH-H2O; the nickel source can include at least one of nickel sulfate, nickel chloride, nickel nitrate, nickel oxalate and nickel acetate; the cobalt source can include at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt oxalate and cobalt acetate; and the raw material containing M element can include at least one of sulfate, chloride, nitrate, oxalate and acetate. The adding amount of the lithium source, the nickel source, the cobalt source and the raw material containing M element is selected according to the content of each element in the ternary positive electrode material. In an embodiment of the present application, the lithium source, the nickel source, the cobalt source and the raw material containing M element can be added into water, stirred for more than 1 h to form a mixed solution; the mixed solution is placed in a hydrothermal kettle (such as a 500 ml polytetrafluoroethylene hydrothermal kettle), sealed and placed in an oven for reaction, and then vacuum dried to obtain the ternary positive electrode material. In an embodiment, the reaction temperature can be 100-200°C, and the reaction time can be 10-24 h. Specifically, the reaction temperature can be, but is not limited to, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, and the reaction time can be, but is not limited to, 10 h, 12 h, 15 h, 18 h, 20 h, 22 h or 24 h. In an embodiment, the reaction temperature can be 100-150°C, and the reaction time can be 15-24 h. In a specific embodiment, the reaction temperature can be 200°C, and the reaction time can be 10 h.

[0042] In an embodiment of the present application, the ternary positive electrode material can be mixed with a carbon source, and then a nitrogen source is introduced, and then heated to obtain the positive electrode active material. The carbon source includes at least one of glucose, sucrose, citric acid and epoxy resin, and the nitrogen source can be but is not limited to ammonia, and the introduction of the nitrogen source can also be through inert gas and reducing gas, such as argon, hydrogen, etc. In an embodiment, the ratio of the amount of inert gas, reducing gas and ammonia introduced can be (70-90):(1-10):(9-20). Specifically, the ratio of the amount of inert gas, reducing gas and ammonia introduced can be but is not limited to 70:10:20, 75:8:17, 80:5:15, 83:5:12, 85:4:11, 88:3:9 or 90:1:9. In a specific embodiment, the ratio of the amount of argon, hydrogen and ammonia introduced can be but is not limited to 80:5:15. The addition of the carbon source or the nitrogen source in the above preparation process can introduce oxygen, or the oxygen contained in the carbon source or the nitrogen source itself is not removed in the above preparation process, so that the carbon and nitrogen coating layer in the positive electrode active material contains oxygen elements. In an embodiment of the present application, the heating includes a temperature rising stage and a temperature holding stage, the temperature rising rate of the temperature rising stage can be 1-10 ℃ / min, the temperature of the temperature holding stage can be 500-800 ℃, and the holding time of the temperature holding stage can be 0.5-5 h, so as to improve the performance and preparation efficiency of the positive electrode active material. Specifically, the temperature rising rate of the temperature rising stage can be but is not limited to 1 ℃ / min, 2 ℃ / min, 3 ℃ / min, 4 ℃ / min, 5 ℃ / min, 6 ℃ / min, 7 ℃ / min, 8 ℃ / min, 9 ℃ / min or 10 ℃ / min, etc., and the temperature of the temperature holding stage can be but is not limited to 500 ℃, 510 ℃, 520 ℃, 530 ℃, 550 ℃, 580 ℃, 600 ℃, 620 ℃, 650 ℃, 700 ℃, 750 ℃ or 800 ℃, etc. In an embodiment of the present application, the temperature of the temperature holding stage can be 500-700 ℃, 520-700 ℃ or 550-650 ℃, etc. In an embodiment of the present application, the heating includes a temperature rising stage and a temperature holding stage, the temperature rising rate of the temperature rising stage can be 3-8 ℃ / min, the temperature of the temperature holding stage can be 600-800 ℃, and the holding time of the temperature holding stage can be 1-4 h. In a specific embodiment, the heating includes a temperature rising stage and a temperature holding stage, the temperature rising rate of the temperature rising stage can be 5 ℃ / min, the temperature of the temperature holding stage can be 800 ℃, and the holding time of the temperature holding stage can be 2 h. The temperature rising stage can be but is not limited to starting from room temperature, and specifically, the room temperature can be but is not limited to 25 ℃, etc.

[0043] Please refer to Figure 2A cross-sectional view of a positive electrode according to an embodiment of the present application is provided, the positive electrode 100 includes a positive electrode current collector 20 and a positive electrode active material layer 30 disposed on the surface of the positive electrode current collector 20, the positive electrode active material layer 30 includes the positive electrode active material according to any one of the above embodiments. The positive electrode active material provided by the present application has a high liquid retention capacity, thereby making the positive electrode have excellent cycle performance, which is beneficial to the use of the positive electrode.

[0044] In the present application, the positive electrode current collector is independently selected from a metal foil or an alloy foil. The metal foil includes copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold or silver foil, and the alloy foil includes stainless steel or an alloy containing at least one of copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold and silver. For example, the positive electrode current collector can be specifically aluminum foil. The thickness and surface roughness of the positive electrode current collector in the present application can be adjusted according to actual needs.

[0045] In the present application, the positive electrode active material layer can further include at least one of a binder and a conductive agent. Specifically, the binder can include at least one of fluorine-containing resin, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyolefin, butadiene styrene rubber, etc.; and the conductive agent can include at least one of conductive carbon black (such as acetylene black, ketjen black), carbon nanotube, carbon fiber and graphite. In an embodiment of the present application, the mass content of the binder in the positive electrode active material layer can be 0.01% to 10%, and the mass content of the conductive agent in the positive electrode active material layer can be 0.1% to 20%. Specifically, the mass content of the binder in the positive electrode active material layer can be but not limited to 0.01%, 0.1%, 0.5%, 1%, 3%, 5%, 8% or 10%, etc., and the mass content of the conductive agent in the positive electrode active material layer can be but not limited to 0.01%, 0.1%, 0.5%, 1%, 3%, 5%, 8%, 10%, 13%, 15% or 17%, etc.

[0046] The present application provides a battery including a negative electrode and the positive electrode according to any one of the above embodiments. The battery provided by the present application has good cycle performance and safety, which is beneficial to long-term use.

[0047] In an embodiment of the present application, the battery further comprises an electrolyte. In an embodiment of the present application, at least part of the positive electrode is immersed in the electrolyte, and at least part of the negative electrode is immersed in the electrolyte, so as to ensure normal operation of the battery. In an embodiment of the present application, the electrolyte comprises a lithium salt and an organic solvent. Specifically, the lithium salt can include, but is not limited to, at least one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium hexafluoroborate, lithium bis-trifluoromethanesulfonimide, lithium trifluoromethanesulfonate, LiC(CF3SO3)2, and LiN(C4F9SO2)(CF3SO3); and the organic solvent can include, but is not limited to, at least one of an ether-based solvent, a nitrile-based solvent, a cyanate-based solvent, a fluoroester-based solvent, a tetrazole-based solvent, a fluorosulfonyl-based solvent, a chlorosulfonyl-based solvent, a nitro-based solvent, a carbonate-based solvent, a dicarbonate-based solvent, a nitrate-based solvent, a fluoroamide-based solvent, a diketone-based solvent, an oxazole-based solvent, and a triazine-based solvent. For example, the organic solvent can include, but is not limited to, at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, and dimethyl carbonate.

[0048] The present application provides a power-consuming device comprising the battery of any of the above embodiments. The battery in the power-consuming device provided by the present application has excellent electrochemical performance, thereby improving the use performance and service life of the power-consuming device. Specifically, the power-consuming device can refer to a vehicle, an electronic device, an energy storage system, etc., and the above battery can be arranged in the power-consuming device in the form of a single battery, a battery module, a battery pack, etc.

[0049] The effects of the technical solutions of the present application are further described below through specific examples.

[0050] Embodiment 1

[0051] LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles with a particle size of 4 μm. LiNi 0.8 Co 0.1 Mn 0.1 O2 and glucose were mixed, and the temperature was raised from room temperature (25 °C) to 650 °C at a temperature raising rate of 5 °C / min under an atmosphere containing argon, hydrogen, and ammonia (the ratio of the amounts of argon, hydrogen, and ammonia introduced was 80:5:15), and sintering was performed at 650 °C to obtain a positive electrode active material, which comprises LiNi 0.8 Co 0.1 Mn 0.1 O2 coated with a carbon-nitrogen coating layer, the mass content of nitrogen in the carbon-nitrogen coating layer is 10%, and the carbon-nitrogen coating layer comprises at least one of carbon and nitrogen.Figure 3 Electron micrograph of the positive electrode active material prepared in Example 1.

[0052] Example 2

[0053] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0054] Example 3

[0055] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0056] Example 4

[0057] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0058] Example 5

[0059] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0060] Example 6

[0061] The same as Example 1 except that the temperature of sintering is 500°C and the mass content of nitrogen element in the carbon-nitrogen coating layer is 20%.

[0062] Example 7

[0063] The same as Example 6 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0064] Example 8

[0065] The same as Example 6 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi

[0066] Example 9

[0067] The same as Example 6 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 4.5 μm.

[0068] Example 10

[0069] The same as Example 6 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 5 μm.

[0070] Example 11

[0071] The same as Example 1 except that the sintering temperature was 700°C and the mass content of nitrogen in the carbon-nitrogen coating layer was 5%.

[0072] Example 12

[0073] The same as Example 11 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 3 μm.

[0074] Example 13

[0075] The same as Example 11 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 3.5 μm.

[0076] Example 14

[0077] The same as Example 11 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 4.5 μm.

[0078] Example 15

[0079] The same as Example 11 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiNi0.8Co0.1Mn0.1O2 single crystal particles was 5 μm.

[0080] Example 16

[0081] The same as Example 1 except that the sintering temperature was 550°C and the mass content of nitrogen in the carbon-nitrogen coating layer was 15%.

[0082] Example 17

[0083] The same as Example 16 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0084] Example 18

[0085] The same as Example 16 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0086] Example 19

[0087] The same as Example 16 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0088] Example 20

[0089] The same as Example 16 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0090] Example 21

[0091] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0092] Example 22

[0093] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0094] Example 23

[0095] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0096] Example 24

[0097] The same as example 1, except that LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles and Al(NO3)3 powder were mixed uniformly according to the element ratio, and then placed in a muffle furnace for 5h at 500℃, and then Al-doped LiNi 0.8 Co 0.1 Mn 0.095 Al 0.005 O2 single crystal particles (particle size 4μm). LiNi 0.8 Co 0.1 Mn 0.095 Al 0.005 O2 and glucose were mixed, and sintered at 650℃ under an atmosphere containing ammonia to obtain a positive electrode active material, which included LiNi 0.8 Co 0.1 Mn 0.095 Al 0.005 O2, and the mass content of nitrogen in the carbon-nitrogen coating layer was 10%.

[0098] Example 25

[0099] The same as example 1, except that the mass content of nitrogen in the carbon-nitrogen coating layer was 9%.

[0100] Example 26

[0101] The same as example 1, except that the particle size of LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles was 1μm, the sintering temperature was 520℃, and the mass content of nitrogen in the carbon-nitrogen coating layer was 50%.

[0102] Example 27

[0103] The same as example 1, except that the particle size of LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles was 2μm, the sintering temperature was 535℃, and the mass content of nitrogen in the carbon-nitrogen coating layer was 38%.

[0104] Example 28

[0105] The same as example 1, except that the particle size of LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles was 4.5μm, the sintering temperature was 535℃, and the mass content of nitrogen in the carbon-nitrogen coating layer was 33%.

[0106] Example 29

[0107] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0108] Example 30

[0109] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0110] Example 31

[0111] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0112] Example 32

[0113] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0114] Example 33

[0115] The same as Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the LiCo

[0116] Example 34

[0117] The same as Example 1 except that LiNi 0.8 Co 0.1Mn 0.1 The particle size of the O2 single crystal particles is 0.8 μm, the sintering temperature is 535° C., and the mass content of nitrogen in the carbon-nitrogen coating layer is 35%.

[0118] Example 35

[0119] It is similar to Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles is 2 μm, the ratio of the introduction of argon, hydrogen and ammonia is 85:5:10, the sintering temperature is 505° C., and the mass content of nitrogen in the carbon-nitrogen coating layer is 0.005%.

[0120] Comparative Example 1

[0121] The same as Example 1, except that the atmosphere during sintering does not contain ammonia, and the positive electrode active material obtained is LiNi coated with a carbon coating layer. 0.8 Co 0.1 Mn 0.1 O2.

[0122] Comparative Example 2

[0123] It is similar to Comparative Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles is 3 μm.

[0124] Comparative Example 3

[0125] It is similar to Comparative Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles is 3.5 μm.

[0126] Comparative Example 4

[0127] It is similar to Comparative Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles is 4.5 μm.

[0128] Comparative Example 5

[0129] It is similar to Comparative Example 1 except that LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles is 5 μm.

[0130] Comparative Example 6

[0131] The same as in Example 1 except that the carbon-nitrogen coating layer was not prepared, and the LiNi 0.8 Co 0.1 Mn 0.1 O2 was directly used as a positive active material.

[0132] Comparative Example 7

[0133] The same as in Example 1 except that the LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles had a particle size of 3 μm, the sintering temperature was 530°C, and the mass content of nitrogen element in the carbon-nitrogen coating layer was 40%.

[0134] Comparative Example 8

[0135] The same as in Example 1 except that the LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles had a particle size of 1 μm, the sintering temperature was 550°C, and the mass content of nitrogen element in the carbon-nitrogen coating layer was 20%.

[0136] Comparative Example 9

[0137] The same as in Example 1 except that the LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles had a particle size of 6 μm, the sintering temperature was 520°C, and the mass content of nitrogen element in the carbon-nitrogen coating layer was 50%.

[0138] Comparative Example 10

[0139] The same as in Example 1 except that the LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles had a particle size of 10 μm, the sintering temperature was 540°C, and the mass content of nitrogen element in the carbon-nitrogen coating layer was 30%.

[0140] Comparative Example 11

[0141] The same as in Example 1 except that the LiNi 0.8 Co 0.1 Mn 0.1 O2 single crystal particles had a particle size of 8 μm, the sintering temperature was 500°C, and the mass content of nitrogen element in the carbon-nitrogen coating layer was 70%.

[0142] Comparative Example 12

[0143] The same as in Example 1 except that the LiNi 0.8 Co0.1 Mn 0.1 The particle size of the O2 single crystal particles was 7 μm, the ratio of the amounts of argon, hydrogen and ammonia introduced was 85:5:10, the sintering temperature was 800°C, and the mass content of nitrogen in the carbon-nitrogen coating layer was 0.005%.

[0144] Comparative Example 13

[0145] The same as in Example 1, except that the LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles was 12 μm, the sintering temperature was 650°C, and the mass content of nitrogen in the carbon-nitrogen coating layer was 10%.

[0146] Comparative Example 14

[0147] The same as in Example 1, except that the LiNi 0.8 Co 0.1 Mn 0.1 The particle size of the O2 single crystal particles was 0.05 μm, the sintering temperature was 700°C, and the mass content of nitrogen in the carbon-nitrogen coating layer was 5%.

[0148] Performance testing

[0149] The above positive electrode active material was mixed with a binder PVDF and a conductive agent carbon nanotube to form a positive electrode slurry; the positive electrode slurry was coated on the surface of an aluminum foil current collector, and after being rolled under a pressure of 1.5 MPa at 25°C, a positive electrode active material layer was formed, thereby obtaining a positive electrode. The mass M0 of the positive electrode and the volume V1 of the positive electrode active material layer were measured. The positive electrode was placed in a LiPF6 electrolyte (in which the concentration of lithium salt was 1 mol / L, and the solvent was ethylene carbonate and dimethyl carbonate), and after being left to stand for 3 h, the mass M1 was measured, and the liquid retention amount Q g / cm2was calculated. 3 The results are shown in Table 1, where Q = (M1-M0) / V1, and the value of Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y) was calculated (to four decimal places), and the results are shown in Table 1 in the column of Formula Value.

[0150] After the above positive electrode active material was made into the same standard button cell, the cycle performance was tested, in which the charging and discharging cycles were carried out under the conditions of 2.5 V-4.3 V and 0.5 C, and the capacity retention rate after 100 cycles is shown in Table 1.

[0151] Table 1 Test Results

[0152]

[0153]

[0154] As can be seen from Table 1, compared with Comparative Examples 1-6, the positive electrode active materials provided in the embodiments of the present application have carbon-nitrogen coating layers, and the batteries prepared from these positive electrode active materials have more excellent cycle performance. Compared with Comparative Examples 7-14, the positive electrode active materials provided in the embodiments of the present application satisfy the relationship -0.05≤Q+0.01(X 2 -100×Y 2 -0.026(3X-10Y)≤0.05, and the batteries prepared therefrom have better cycle performance. Compared with Examples 32-35, the batteries prepared from the positive electrode active materials provided in other examples have better cycle performance. Therefore, the batteries prepared from the positive electrode active materials provided in the present application have excellent cycle performance, thereby facilitating the use of the batteries.

[0155] The above describes the preferred embodiments of the present application, but should not be construed as limiting the scope of the present application. It should be noted that for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements are also considered within the protection scope of the present application.

Claims

1. A positive electrode active material, characterized in that The invention comprises a ternary positive electrode material and a carbon-nitrogen coating layer covering the ternary positive electrode material, wherein the particle size of the single crystal particles of the ternary positive electrode material is X μm, the mass content of the nitrogen element in the carbon-nitrogen coating layer is Y, Y is not 0, and the liquid retention capacity of the positive electrode active material is Q g / cm 3 , the X, the Y and the Q satisfy: -0.05≤Q+0.01(X 2 -100×Y 2 )-0.026(3X-10Y)≤0.05, wherein the volume of the positive electrode active material layer containing the positive electrode active material is V1, the mass of the positive electrode having the positive electrode active material layer is M0, and the mass of the positive electrode after standing in the electrolyte for 3 hours is M1, and Q=(M1-M0) / V1.

2. The positive electrode active material according to claim 1, wherein The X is 1-10.

3. The positive electrode active material according to claim 1, wherein The Y is 0.01% to 50%.

4. The positive electrode active material according to any one of claims 1 to 3, characterized in that The X is 3.5-4.5, and the Y is 9%-15%.

5. The positive electrode active material according to claim 1, wherein The Q is greater than 0.

11.

6. The positive electrode active material according to claim 1, wherein The thickness of the carbon-nitrogen coating layer is less than or equal to 1 μm.

7. The positive electrode active material according to claim 1, wherein The mass content of carbon element in the positive electrode active material is 0.1% to 2%.

8. The positive electrode active material according to claim 1, wherein The ternary positive electrode material includes Li α Ni β Co γ M 1-β-γ O2, wherein 0.98≤α≤1.02, 0<β<1, 0<γ<1, and the M is selected from at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo and Mn.

9. The positive electrode active material according to claim 1, wherein The form of the nitrogen element in the carbon-nitrogen coating layer includes at least one of pyridinic nitrogen, pyrrolic nitrogen, graphitized nitrogen and nitrogen oxide.

10. A positive electrode, characterized in that The invention comprises a positive electrode current collector and a positive electrode active material layer provided on the surface of the positive electrode current collector, wherein the positive electrode active material layer comprises the positive electrode active material according to any one of claims 1 to 9.

11. A battery, characterized in that: The invention comprises a negative electrode and the positive electrode according to claim 10.

12. An electrical device, characterized in that: Including the battery according to claim 11.

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