Difference of rate performance between discharge and charge reactions for bismuth fluoride electrode in lithium-ion battery

Abstract

The conversion-based BiF₃ is a promising cathode material for lithium-ion batteries due to its high theoretical capacity (302 mAh g⁻¹). Nanocomposites of BiF₃ and carbon (BiF₃/C) are known to improve the electrochemical performance by increasing the electronic conductivity of the electrode. Here we investigate the electrochemical performance of BiF3/C at high C-rates. In particular, we newly investigate the difference of high C-rate performance between discharge and charge reactions. The discharge and charge capacities in the first cycle were almost the same at 0.1 C. In contrast, the discharge capacity was higher than charge capacity at 10 C. Further, during cycling at 10 C, the charge capacity drastically decreased, but the discharge capacity remained high. The rate performance of the discharge reaction was higher than that of the charge reaction, especially after cycling.