Visualization of the State-of-Charge Distribution in a LiCoO2 Cathode by In Situ Raman Imaging

High-speed and high-definition in situ Raman imaging was used to investigate the local state-of-charge (SOC) distribution in a LiCoO2 cathode during charge/discharge cycling. The local SOC varied significantly as a function of the location on the LiCoO2 electrode surface during charge/discharge processes and the SOC distribution was broadened after cycling. This change of the SOC distribution is caused by an increase in the electronic resistance between LiCoO2 particles. The in situ Raman imaging technique enabled observation of the Li+ transport in the LiCoO2 electrode during charge/discharge cycling.