A high-performance intermediate-temperature aluminum-ion battery based on molten salt electrolyte

Non-aqueous rechargeable aluminum-ion batteries (AIBs) are a promising candidate for grid-scale energy storage due to their high theoretical energy density , safety, environmental benignity, and the abundance of Al sources. However, the limited cathode capacity and the high price of ionic liquid electrolytes hinder their large-scale applications. Herein, an intermediate-temperature AIB composed of nickel disulfide-based cathode and NaCl-AlCl 3 -Al 2 S 3 molten salt electrolyte is reported. A highly reversible conversion mechanism between Ni 3 S 4 and Ni during cycling is proved with cathode capacities exceeding 500 mAh g −1 . The full cell delivers a cathode capacity of 320 mAh g −1 at 240 °C and a current density of 2000 mA g −1 with negligible capacity fade after 2000 cycles. The raw material cost is estimated to be as low as 28 $ kWh −1 based on the electrode and electrolyte materials. The molten salt electrolyte-based AIB provides promising opportunities to build energy storage systems with low cost, high safety, stable electrochemical performance, and long lifetime.