Preparation method of Ni-Co-Al ternary precursor with continuous concentration gradient

Abstract

The invention relates to the field of preparation of a lithium ion battery positive electrode material, in particular to a preparation method of a Ni-Co-Al ternary precursor with continuous concentration gradient. The preparation method is characterized by comprising the steps of (1) combining and adding a mixed solution of a nickel solution, a cobalt solution, an aluminum solution, a complexing agent and a precipitant into a reaction kettle; (2) adding deionized water into the nickel solution during the material addition process, adding a high-concentration cobalt solution into the cobalt solution until the concentration of the nickel solution is 0.1M or the concentration cobalt solution is 1M, stopping adding a raw material, constantly stirring to ensure uniform solution during the wholeprocess, controlling a pH value of a reaction system to 10.5-12 and temperature to 55-65 DEG C, and continuing to age for 6-24 hours after material addition is stopped; and (3) taking out the material for solid-liquid separation, washing and drying to obtain the Ni-Co-Al ternary precursor with continuous concentration gradient after aging.

Description

technical field [0001] The invention relates to the field of preparation of cathode materials for lithium ion batteries, in particular to a method for preparing a nickel-cobalt-aluminum ternary precursor with a continuous concentration gradient. Background technique [0002] Lithium-ion batteries have a series of advantages such as high energy density and long cycle life, and have been widely used in digital, energy storage and electric vehicles. At present, the energy density of lithium batteries is mostly 140wh / kg, and the corresponding cruising range of electric vehicles is about 300 kilometers, which is far from meeting people's requirements for long cruising range of cars. [0003] In order to develop a lithium-ion battery with higher energy density, researchers focus their work on the positive electrode material of the battery, because the performance of the positive electrode material largely determines the performance of the battery. The nickel-cobalt-aluminum terna...

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Problems solved by technology

For example, Chinese patent CN103715424B discloses a core-shell structure positive electrode material and its preparation method. It first precipitates nickel and cobalt, and then deposits a layer of aluminum hydroxide on the surface. However, the aluminum layer on the surface is in the electrochemical reaction. Does not participate in the reaction, and reduces the electronic conductivity and ion diffusivity of the material, so that the capacity cannot be effectively exerted, and the energy density of the battery is low

Another example is the Chinese patent CN106207140A which discloses a method for preparing nickel-cobalt-aluminum composites with multiple core-shell structures. A precursor with high internal nickel content and low external nickel content is prepared through multiple co-precipitation reactions. The precursor prepared by this method consists of several The composition of the coating layer with different concentrations of nickel and cobalt in the layer, there is an interface between the coating layers, due to the different components between the coating layers, different volume changes occur during the charging and discharging process of the battery, and the cycle performance of the battery deteriorates

In addition, the process is complex and not suitable for industrial production

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