A High Voltage Aqueous Zn-Graphite Battery Utilizing "Water-in-Salt" Electrolyte

Aqueous zinc-based batteries have the potential to be used for large-scale energy storage because they are inexpensive, safe, and environmentally friendly. However, their energy density is limited because they use low-voltage cathodes and electrolytes. Graphite could be a suitable cathode material for these batteries because it has a high redox potential. However, finding a stable aqueous electrolyte that can handle the high voltage is a major challenge. This study presents a low-cost aqueous zinc-graphite dual-ion battery that uses a Zn(ClO 4 ) 2 water-in-salt electrolyte with a wide electrochemical window of 2.80 V. This electrolyte, which contains strong chaotropic ClO 4 − anions, allows for the reversible plating and stripping of zinc ions with a low overpotential and a high upper cut-off potential. As a result, the battery is able to deliver a maximum discharge capacity of 45 mA h g −1 at a discharge rate of 100 mA g −1 with a mean discharge voltage of around 1.95 V vs Zn 2+ /Zn and can be used for over 500 cycles. References: A. Z. A. Zafar, et al, Journal of Materials Chemistry A, 10 (2022) 2064-2074. A. Zafar, M. Šilhavík, J. Červenka , Patent LU101731