Effect of electrochemically active surface area on the charge-transfer resistance of layered positive electrode materials

Abstract

Clarifying the relationship between the electrochemically active surface area and power capability is important for producing high-power batteries. In this study, the impact of particle morphology on the electrochemical kinetics of LiNi_1/3Co_1/3Mn_1/3O₂ (NCM) materials was investigated via rate-capability tests and electrochemical impedance spectroscopy using diluted NCM electrodes. In particular, different sizes and shapes of NCM materials were compared. The rate capability was governed by the particle size and shape, which were correlated with the Li-ion diffusion length and electrochemically active surface area. In addition, charge-transfer resistance was inversely proportional to the electrochemically active surface area, highlighting the importance of facet engineering. Therefore, optimising the particle morphology to selectively enhance active surfaces supports high-power and high-rate capabilities.