Study of the coating effect of mildly oxidized graphene on aluminium current collectors by electrophoretic deposition and drop-casting methods for Li-ion battery application

Abstract

Preventing current collector corrosion is critical in Li-ion batteries. This study investigates mildly oxidized graphene (MGO) coating on aluminium (Al) foil for corrosion resistance and battery performance for the first time. Electrophoretic deposition (EPD) and drop-casting are used to apply this coating. Polarization tests and SEM analysis are performed on coatings to determine the optimal EPD conditions. Optimal conditions for EPD of MGO on aluminium are 5 V and 40 s. Using LiNi0.8Co0.15Al0.05O2 (NCA) cathodes, the performance of cells on MGO-coated and uncoated aluminium (Bare-Al) is evaluated. EPD sample shows a capacity of 175 mAh/g at C/2, 35 mAh/g more than the Bare-Al sample despite a 67.3 Ω increase in charge transfer resistance (Rct). Due to inadequate adhesion, the drop-casted sample displays a 136 mAh/g capacity at C/2, poor rate capability, and higher Rct (335.48 Ω). MGO-coated aluminium batteries perform better under the EPD method because of improved corrosion resistance of current collectors, as demonstrated by reduced corrosion currents in the polarization curves and reduced conductivity losses in incremental capacity (ICA) results.