Modification method for reducing residual alkali on surface of high-nickel ternary positive electrode material, prepared high-nickel ternary positive electrode material and lithium ion battery

Abstract

The invention discloses a modification method for reducing residual alkali on the surface of a high-nickel ternary positive electrode material, which comprises the following steps of (1) uniformly mixing the high-nickel ternary positive electrode material with a solvent to form slurry, and (2) rapidly leaching the slurry with a solvent, then carrying out filter pressing and drying, and sintering the dried product to obtain the high-nickel ternary positive electrode material with low residual alkali, The solvent is selected from one or a mixture of more of deionized water, ammonia water and alcohol. According to the method, the high-nickel ternary positive electrode material is pulped, and then residual alkali on the surface of the material is reduced by a rapid leaching method, so that theresidual alkali on the surface of the material is further reduced; under the condition that the specific surface area is not obviously increased, LiOH and Li2CO3 on the surface of the material are reduced; meanwhile, the removal of lattice lithium is reduced, the first specific discharge capacity of the high-nickel ternary positive electrode material is not reduced due to water washing, the high-temperature cycle performance and the high-temperature storage performance of the high-nickel ternary positive electrode material are further improved, and the increase of high-temperature cycle DCR is reduced.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a modification method for reducing residual alkali on the surface of a high-nickel ternary positive electrode material. Background technique [0002] Nickel cobalt lithium manganate material LiNi x mn y co z o 2 In (x+y+z=1), the value of x is higher than 0.6, which is generally called a high-nickel ternary cathode material. Ni acts as an active component in a ternary cathode material. The higher the Ni content, it can participate in electrochemical reactions. The more electrons there are, the higher the specific discharge capacity of the material. With the increase of the country's requirements for the energy density of power batteries, and the introduction of subsidies and energy density-linked policies, it has greatly promoted the application and development of high-nickel ternary cathode materials. . In the ternary material system, with the increase of nick...

AI Technical Summary

Problems solved by technology

Too much residual lithium on the particle surface will bring many hazards. For example, too high residual lithium on the surface of the material will cause a higher pH value, and too high residual alkali will cause gelation of the slurry during the preparation of the electrode sheet, resulting in Uneven slurry coating forms jelly, which affects the coating; leads to poor high-temperature storage performance of the battery and serious swelling; leads to poor high-temperature cycle performance of the power battery, cycle diving and other problems

[0003] The method commonly used to reduce the residual alkali on the surface of high-nickel materials is mainly water washing. Stirring and washing, and then draining the water, this method can effectively reduce the residual alkali on the surface of high-nickel materials, but the shortcomings of this method are also very obvious. During the washing process, the LiOH and Li on the surface 2 CO 3 Continuously dissolved in water, the Li in the lattice + continue to move out, eventually leading to the Li on the surface of the material 2 CO 3 On the high side, Li in the lattice + 2) Secondary sintering through water phase coating, although this method can uniformly coat the surface of the material, thereby improving the cycle performance of the material, but the positive electrode material The first charge and discharge efficiency drops greatly, and it is not suitable for coating with high nickel materials

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