In-situ synthesis method of fast ion conductor inlaid lithium ion battery cathode material

Abstract

The invention discloses an in-situ synthesis method of fast ion conductor inlaid lithium ion battery cathode material. Nickel salt, cobalt salt, M salt (M is one of Mn or Al) and a surface active agent are added into a solvent, and precursor powder is prepared through a spray drying method. Precursor is subjected to presintering, so that spherical porous nickel / cobalt / M-based precursor is obtained. Appropriate lithium salt, an organic sequestering agent, a solvent and a fast ion conductor material are mixed through a sol-gel heat treating method, so as to obtain sol, and then the spherical porous precursor is spread in the sol till the solvent is evaporated to form gel, and the fast ion conductor inlaid composite cathode material is synthesized through heat treatment. The method abandons the thinking that the cathode material is firstly prepared and then surface modification is performed in the traditional technology, and realizes the in-situ growth of inlaid composite material. The surface layer of the inlaid composite material adopts a uniformly coated fast ion conductor thin layer, the inner core adopts fast ion conductor doped cathode material, and the inlaid composite material has the advantages of excellent electrochemical property, good safety and storage performance and the like.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and relates to an in-situ synthesis method of fast ion conductor mosaic type lithium ion battery cathode materials. Background technique [0002] Among many secondary battery systems, lithium-ion batteries are favored by people because of their high operating voltage, high energy density, and long cycle life. At present, the commercial cathode material is mainly lithium cobalt oxide (LiCoO 2 ), but LiCoO 2 The actual specific capacity is low, and the synthesis requires a large amount of expensive cobalt, which limits its application. Nickel-rich ternary material (LiNi 0.8 co 0.1 mn 0.1 o 2 、LiNi 0.8 co 0.15 Al 0.05 o 2 etc.) have become the new darling of positive electrode materials due to their advantages such as high discharge specific capacity and relatively low cost. However, there are still many problems to be solved urgently in this kind of materials. (1) The interface stab...

AI Technical Summary

Problems solved by technology

However, there are still quite a lot of problems to be solved urgently in this kind of materials.

(1) The interface stability of the material is poor

In high delithiation state (≥4.3V), Ni 3+ converted to unstable Ni 4+ , easy to react with the electrolyte, generate non-conductive NiO on the surface of the material, and release heat and gas, causing an increase in interface impedance, deterioration of cycle performance and safety

(2) The material is easy to absorb moisture when stored in the air, which not only reduces the conductivity of the interface, but also leads to excessive viscosity of the material in the subsequent pulping process, which affects the smoothness of the coating

(3) The cation mixing phenomenon of the material is serious, resulting in the first charge and discharge Coulomb efficiency is not high (about 80%), and the reversible capacity is reduced

(4) The lithium ion diffusion coefficient of the material is not high, which is 10 -11 cm 2 ·S -1 , lower than LiCoO 2 of 10 -9 cm 2 ·S -1 , the rate performance needs to be enhanced

So far, there is no report about using this method to prepare lithium-ion cathode materials with this structure

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