Commercial expanded graphite as a low–cost, long-cycling life anode for potassium–ion batteries with conventional carbonate electrolyte

Design and synthesis of capable anode materials that can store the large size K⁺ is the key of development for potassium–ion batteries. The low–cost and commercial expanded graphite with large particles is a graphite–derived material with good conductivity and enlarged interlayer spaces to boost the potassium ion diffusion coefficient during charge/discharge process. Thus, we achieve excellent anode performance for potassium–ion batteries based on an expanded graphite. It can deliver a capacity of 263 mAh g⁻¹ at the rate of 10 mA g⁻¹ and the reversible capacity remains almost unchanged after 500 cycles at a high rate of 200 mA g⁻¹ with a coulombic efficiency of around 100%. The potassium storage mechanism is investigated by the ex situ XRD technique. This excellent potassium storage performance will make the expanded graphite promising anode candidate for potassium ion batteries.