Kinetics of Li+ transport and capacity retention capability of HT- LiCoO2 films

Abstract

In this work, HT-LiCoO2 films with preferential c-axis orientation were prepared using pulsed laser deposition. The kinetics of lithium ion transport through the HT-LiCoO2 film was investigated by applying potentiostatic intermittent titration technique (PITT). The capacity retention capability of the HT-LiCoO2 film was studied using constant-current (CC) cycling. PITT measurement showed that the lithium chemical diffusion coefficient () of the HT-LiCoO2 films reached as high as 10−8–10−10 cm2 s−1 and the value of in the two-phase coexistence region was lower than that in other single-phase regions. CC cycling revealed that the HT-LiCoO2 film delivered an initial discharge capacity of 40 μAh μm−1 cm−2 and the discharge capacity decreased to 22.4 μAh μm−1 cm−2 after 100 CC cycles. The observation was found to be caused by the continuous formation of the spinel phase (LiCo2O4 or Co3O4).