Novel zinc-based molten salt batteries with high voltages in medium temperature environment

Abstract

Since single energy storage system like thermal storage has low energy conversion efficiency and large energy losses, integrated energy storage technology holds great promise in future energy storage modes. In order to alleviate the shortage of energy conversion efficiency in thermal storage, the combination with electrochemical energy storage will bring great improvements. However, most batteries have the limitations of operating temperature and dangerous highly reactive metals, which are not conducive to practical large-scale energy storage. To this regard, safe novel zinc-based molten salt batteries are developed which can operate in medium temperature environments and are free of highly reactive metals. The batteries realize high cell voltages of over 1 V in 300 °C by utilizing zinc metal anodes and MnO2, V2O5 cathodes in Zn–K–Cl melts and can operate at large currents more than 30 mA cm−2. The results show that Zn2+ will continuously intercalate into the cathodes during discharge processes and resulting in the transformation of the oxide cathodes and the reduction of the cathode transition metals, which indicates the discharge mechanisms based on Zn2+ intercalation. Therefore, the batteries have certain cycling capabilities which have been experimentally verified, illustrating the promising prospects of these novel zinc-based molten salt batteries.