Enabling Natural Graphite in High-Voltage Aqueous Graphite || Zn Metal Dual-Ion Batteries

Safety and cost are the key metrics for large-scale energy storage. Due to the use of nonaqueous electrolytes and transition metal oxides in current lithium-ion battery technologies, safety, cost, and environmental issues are a significant cause for concern. Graphite is a promising cathode material for dual-ion batteries due to its high operating potential, low cost, and high safety. Nevertheless, it is challenging to find a suitable aqueous electrolyte due to the narrow electrochemical stability window (1.23 V). This work presents a graphite || zinc metal aqueous dual-ion battery of approximate to 2.3-2.5 V, a remarkably high voltage in aqueous zinc batteries, achieving >80% capacity retention after 200 cycles and delivering approximate to 110 mAh g(-1)at a charge/discharge current of 200 mA g(-1). A capacity of nearly 60 mAh g(-1)is achieved at a charge/discharge current of 5000 mA g(-1). Natural graphite is enabled as a reversible cathode using a highly concentrated lithium-free bisalt aqueous electrolyte.