Electrochemical characteristics of high-capacity Mg/V2O5 hybrid batteries with Mg-Li dual salt electrolytes

Abstract

Mg-Li hybrid cells are constructed and evaluated using a V2O5 positive electrode, a Mg metal negative electrode, and Mg-Li dual salt electrolytes. When a crystalline V2O5 (c-V2O5) and an Al current collector are used, side reactions can occur even at the upper voltage limit of 2.4 V (vs. Mg/Mg2+). However, when an amorphous V2O5 (a-V2O5) is used with a Ti current collector, the side reactions are greatly reduced and the cycle performance is improved. The discharge capacity and Coulombic efficiency at the second cycle are 187 mA h g−;1 and 94.9%, respectively. a-V2O5 is more electrochemically stable than c-V2O5, the Mg/a-V2O5 cell shows a discharge voltage of ∼1.5 V and a specific capacity of 148 mA h g−1 even after 20 cycles. Therefore, the a-V2O5 is a potential host material for Mg-Li hybrid batteries.