Visualization of the State-of-Charge Distribution in a LiCoO₂Cathode 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 LiCoO 2 cathode during charge/discharge cycling. The local SOC varied significantly as a function of the location on the LiCoO 2 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 LiCoO 2 particles. The in situ Raman imaging technique enabled observation of the Li + transport in the LiCoO 2 electrode during charge/discharge cycling.