Kinetic and transport characteristics of LiNi0.8Co0.1Mn0.1O2 lithium-ion batteries

A balance must be found between energy density, cost and life for energy-typed lithium-ion batteries. Solving this problem requires a deep understanding of the electrode interface reaction mechanism. In this paper, electrochemical AC impedance spectroscopy (EIS) is used to study the impedance spectrum characteristics of lithium-ion batteries comprising LiNi0.8Co0.1Mn0.1O2 (NCM811) and graphite electrodes separately in a symmetrical battery system under different states of charge and temperature. The de Levie - Finite Length Pore (Ls) element is used to differentiate Li+ diffusion resistance Rion inside the porous electrode and charge transfer process resistance Rct in the Faraday reaction. The dependencies of Rion and Rct on temperature and state of charge (SOC) are obtained. Based on the Rion measurements, we calculate MacMullin number (Nm) and then characterize the difficulty of Li ion transportation of NCM811 and graphite electrodes in one cell. The results indicate directions for improving the power design of commercial energy-typed lithium-ion power batteries.