Electrochemically Exfoliated Graphene Electrode for High-Performance Rechargeable Chloroaluminate and Dual-Ion Batteries

The current state-of-the-art positive electrode material for chloroaluminate ion batteries (AIBs) or dual-ion batteries (DIBs) is highly crystalline graphite; however, the rate capability of this material at high discharge currents is significantly reduced by the modest conductivity of graphite. This limitation is addressed through the use of graphene-based positive electrodes, which can improve the rate capability of these batteries due to their higher conductivity. However, conventional methods of graphene production induce a significant number of defects, which impair the performance of AIBs and DIBs. Herein, we report the use of a defect-free graphene positive electrode, which was produced using the electrochemical exfoliation of graphite in an aqueous solution with the aid of Co2+ as an antioxidant. The Co-treated graphene electrode achieved high capacities of 150 mAh g–1 in DIBs and 130 mAh g–1 in AIBs with high rate capability for both batteries. The charge–discharge mechanism of the batteries is examined using in situ Raman spectroscopy, and the results revealed that the intercalation density of [AlCl4]− or [PF6]− increased from a dilute staging index graphite intercalation compound (GIC) to a stage 1 GIC within the operating voltage window. The simple production method of high-quality graphene in conjunction with its high performance in DIBs should enable the use of graphene for DIB technologies.