An advanced Ni–Graphite molten salt battery with 95 °C operating temperature for energy storage application

Based on the high safety and low costs, molten salt batteries (Na-S battery, liquid metal battery, ZEBRA battery, etc.) have received more and more attention as large-scale electrical storage technology. However, the high operating temperature of molten salt batteries is still one of the roadblocks that impeded their practical application. Here we present the novel Ni-graphite molten salt battery based on outstanding electrochemical reversibility of the Ni/NiCl2 redox and intercalation/de-intercalation chemistry of chloroaluminate anions in graphite. By using the low-cost, quaternary inorganic molten salt AlCl3/KCl/NaCl/LiCl as electrolyte, the as-designed Ni-graphite battery possesses low operating temperature of 95 °C, and average voltage about 1.7 V. The Ni-graphite battery delivers stable specific capacity of 174 mAh/g at 500 mA/g after 120 cycles, with the capacity retention rate of 98%. In addition, the Ni-graphite battery also shows low material costs about 113.6 $/kWh and high electrode energy density of 289 Wh/kg. This work develops an advanced molten salt battery with low operating temperature and high energy density, as well as provides an alternative means of developing future large-scale power storage equipment based on molten salt batteries.