High-nickel positive electrode material for non-aqueous electrolyte secondary battery and preparation method for high-nickel positive electrode material

Abstract

The invention discloses a high-nickel positive electrode material for a non-aqueous electrolyte secondary battery and a preparation method for the high-nickel positive electrode material. The high-nickel positive electrode material is represented by a general formula: Li<w>Ni<1-x-y>Co<x>Mn<y>M<z>O<2>, wherein an average particle diameter D50 is 8-15 [mu]m, and is formed by the small particle sizeD50 of 2-5 [mu]m and the small particle size D50 of 8-18 [mu]m, the Co content (metal molar ratio, SC) of the small particle diameter is higher than the Co content (metal molar ratio, LC) of the largeparticle diameter, and the Co concentration ratio (SC / LC) is preferably from the range of 1.2-2. According to the invention, the material structure of the high-nickel positive electrode material is stabilized through element doping and coating, and the crystal structure of the material is stabilized by increasing the cobalt content in the small particle size, and the cycle performance of the material is improved; and finally, the small particle size and the large particle size are mixed according to different proportions, so that the tap density of the positive electrode material and the compaction density of a pole piece are improved.

Description

technical field [0001] The invention relates to a positive electrode material for a non-aqueous electrolyte secondary battery, in particular to a high-nickel positive electrode material composed of a high-nickel composite oxide. technical background [0002] With the rapid development of new energy vehicles, the demand for power batteries continues to increase. In recent years, new energy vehicles have higher and higher requirements for cruising range, and higher energy density, cycle performance and safety performance of lithium-ion batteries. challenge. High-nickel cathode materials, because of their high capacity and low cost, have become the focus of attention of cathode materials and have a very broad market in the field of power batteries. [0003] Due to the high nickel content of high nickel-based positive electrode materials, the radius of lithium ions with the radius of nickel It is relatively close, and it is easy to produce mixed lithium and nickel, which af...

AI Technical Summary

Problems solved by technology

[0003] Due to the high nickel content of high nickel-based positive electrode materials, the radius of lithium ions with the radius of nickel It is relatively close, and it is easy to produce mixed lithium and nickel, which affects the structural stability of the material, and then affects its electrochemical performance; the particle size distribution of high-nickel cathode materials on the market is mostly normal distribution, and the vibration The solid density is low, and the compaction density of the pole piece is low. When the pole piece is rolled, it is easy to cause the secondary particles to be broken, resulting in poor contact between the material and the conductive agent and the binder, and the particles are broken at the same time. The area of ​​the interface between the material and the electrolyte is increased, which affects its electrochemical performance; the particle size distribution of the mixture of large particle size and small particle size is a non-normal distribution with two peaks, because the small particle size particles can be filled between the large particles In the gap between the particles, the tap density of the material and the compaction density of the pole piece can be effectively increased, but due to the large specific surface area of ​​the small particle size material, there are more side reactions between the material and the electrolyte, and the cycle stability of the material becomes poor.

The application number is 201710706178.1 The crystal structure of the material is stabilized by element doping, the residual alkali is reduced by water washing, and the electrochemical stability and safety are improved by coating, but the tap density of the sample prepared by this method is relatively low; while the application number is 201510545968.7 Precursors with different particle sizes are used to prepare materials with different particle sizes, and materials with different particle sizes are mixed to increase the material density, but the reaction between small particle sizes and electrolytes is often not considered carefully

Good cycle performance and high tap density of the material cannot be achieved at the same time, so it is necessary to develop a new type of high-nickel cathode material to improve the above problems

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