Method for improving synthetic particle size uniformity of lithium ion battery positive gradient distribution material precursor and application of precursor

Abstract

The invention discloses a method for improving the synthetic particle size uniformity of a lithium ion battery positive gradient distribution material precursor Ni0.6Co0.2Mn0.2(OH)2 and application of the precursor. The method comprises the following steps: firstly taking nickel salt, cobalt salt and manganese salt to prepare a solution A, a solution B and a solution C with different molar ratios and identical concentrations; then feeding in a gradually-mixing manner and synchronously regulating and controlling the ammonia concentration and a pH value in a reaction system in the feeding process; finally preparing the precursor which is slowly reduced from core Ni to Co to Mn=8:1:1 to material surface Ni to Co to Mn=1:1:1 through co-precipitation reaction. The gradient distribution material precursor Ni0.6Co0.2Mn0.2(OH)2 disclosed by the invention is higher in tap density, excellent in material performance and uniform in material particles.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a material precursor Ni that improves the gradient distribution of the positive electrode of lithium-ion batteries. 0.6 co 0.2 mn 0.2 (OH) 2 Methods for Synthesizing Particle Size Uniformity and Applications of Their Precursors. Background technique [0002] The biggest problem with the current cathode material ternary high-nickel material is its safety and capacity retention. The inherent structure of the high-nickel material itself shows poor thermal stability, which is the biggest challenge for the commercialization of this type of cathode material. Ni 4+ It is extremely unstable in the charged state, especially at high temperature, and has side reactions with the electrolyte, which is the main reason for the shortened cycle life. High-nickel materials easily generate impurities LiOH and Li in the air 2 CO 3 , LiOH is extremely easy to combine with LiPF in...

AI Technical Summary

Problems solved by technology

[0002] The biggest problem with the current cathode material ternary high-nickel material is its safety and capacity retention. The inherent structure of the high-nickel material itself shows poor thermal stability. The biggest challenge facing the commercialization of this type of cathode material

Ni 4+ It is extremely unstable in the charged state, especially at high temperature, and has a side reaction with the electrolyte, which leads to the main reason for the shortened cycle life

High-nickel materials easily generate impurities LiOH and Li in the air 2 CO 3 , LiOH is extremely easy to combine with LiPF in the electrolyte 6 A side reaction occurs to generate HF, while Li 2 CO 3 It is easy to swell when charging, causing safety hazards

Moreover, during the charge and discharge process, the high nickel material undergoes a serious phase change, resulting in an increase in irreversible capacity and unsatisfactory capacity retention.

In addition, the existing positive electrode gradient distribution materials have more small particles and slag, and the overall tap density of the material is low; moreover, high-nickel materials and low-nickel materials are mixed in small particles, and the performance of the formed gradient distribution materials is not very good.

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