Advanced intermediate temperature sodium copper chloride battery

Sodium metal chloride batteries, also called as ZEBRA batteries, possess many merits such as low cost, high energy density and high safety, but their high operation temperature (270-350 °C) may cause several issues and limit their applications. Therefore, decreasing the operation temperature is of great importance in order to broaden their usage. Using a room temperature ionic liquid (RTIL) catholyte composed of sodium chloride buffered 1-ethyl-3-methylimidazolium chloride-aluminum chloride and a dense β″-aluminates solid electrolyte film with 500 micron thickness, we report an intermediate temperature sodium copper chloride battery which can be operated at only 150°C, therefore alleviating the corrosion issues, improving the material compatibilities and reducing the operating complexities associated with the conventional ZEBRA batteries. The RTIL presents a high ionic conductivity (0.247 S cm^-1) at 150°C and a wide electrochemical window (-2.6 to 2.18 vs. Al³⁺/Al). With the discharge plateau at 2.64 V toward sodium and the specific capacity of 285 mAh g^-1, this intermediate temperature battery exhibits an energy density (750 mWh g^-1) comparable to the conventional ZEBRA batteries (728-785 mWh g^-1) and superior to commercialized Li-ion batteries (550-680 mWh g^-1), making it very attractive for renewable energy integration and other grid related applications.