Preparation method of full-concentration gradient positive electrode material precursor, full-concentration gradient positive electrode material and preparation method of full-concentration gradient positive electrode material

Abstract

The invention discloses a preparation method of a full-concentration gradient positive electrode material precursor, a full-concentration gradient positive electrode material and a preparation method of the full-concentration gradient positive electrode material. The method comprises the following steps: (1) adding a nickel-poor solution into a nickel-rich solution to obtain a metal salt solution, adding the metal salt solution, a precipitator a and a complexing agent a into a base solution containing the precipitator and the complexing agent at the same time, and controlling the pH in a reaction system and the concentration of the complexing agent to be gradually reduced along with the reduction of the nickel concentration in the added metal salt solution; and (2) separating, washing and drying the product obtained in the step (1) to prepare the full-concentration gradient positive electrode material precursor with excellent crystallinity. And then preparing the full-concentration gradient positive electrode material with a lithium source. The positive electrode material inherits the excellent crystallinity of the precursor, has high nickel content, high specific discharge capacity and stable structure, is not easy to generate microcracks in the charge-discharge process, and avoids additional side reaction, so that the positive electrode material also has excellent cycle performance.

Description

technical field [0001] The invention belongs to the technical field of preparation of positive electrode materials for lithium ion batteries, and in particular relates to a method for full concentration gradient positive electrode materials. Background technique [0002] As a green energy source with high energy density, lithium-ion batteries are widely used in various 3C digital fields and electric vehicles. Although the current lithium-ion batteries can meet the needs of small devices, they still need higher energy density and better life to meet the needs of electric vehicle power batteries. Therefore, further improving the energy density and cycle performance of lithium-ion batteries has become the next step development core. Lithium-ion battery cathode material is not only the decisive factor of battery cost, but also determines the energy density and life of the battery. Among them, the lithium-ion battery ternary cathode material LiNi 1-x-y co x mn y o 2 Due to i...

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Problems solved by technology

The publication number is CN105552361A, which synthesizes gradually changing shells by adjusting the addition ratio of the aluminum salt complexing solution in real time, but does not regulate the pH in real time; the publication number is CN111276680A, which uses the control of different reaction stages to add precipitants and complexing agents with different flow rates to regulate System pH and complex atmosphere to prepare core-shell structure precursors, but this regulation method has great disadvantages, which are reflected in the fact that the regulation method is intermittent, uncontrollable, and slow feedback, which cannot make the atmosphere of the system continuous Changes, there may be a sudden drop in the system atmosphere, resulting in a thermodynamic imbalance of coprecipitation

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