Size effect on electrochemical property of nanocrystalline LiCoO₂ synthesized from rapid thermal annealing method

Nano-sizing of cathode materials for higher power Li-ion rechargeable batteries is an effective method to shorten a Li-ion diffusion path and achieve fast charge transfer. Nanocrystalline LiCoO₂ was synthesized through a combination of rapid thermal annealing method and a sol-gel method assisted with a triblock copolymer surfactant, and the electrochemical properties including the Li-ion chemical diffusion coefficient was investigated. Li-ion deintercalation/intercalation experiments suggested an extreme small amount of cation mixing between Li⁺ and Co³⁺ within a layered structure of LiCoO₂, which was not observable in the Raman spectroscopy. The analysis based on the solution for the diffusion equation of the cylinder model revealed that the cation mixing strongly decelerates the Li-ion diffusion in LiCoO₂.