High-Entropy Quintuple Alloys toward Efficient Dual-Ion Engineered Energy Storage Systems

Seawater is one of the most abundant natural resources on Earth. Developing safe, rechargeable batteries that use a seawater-derived chloride electrolyte can lead to efficient, low-cost energy storage with stable charge–discharge cycles. This approach promises significant economic and environmental benefits and can greatly broaden the applications of alkali metal batteries. However, establishing an efficient and reversible chloride–chlorine reaction cycle is more advantageous for energy storage and conversion as well as challenging with respect to the air electrode processes including the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). We develop a FeCrMnNiCo high-entropy alloy catalyst-based zinc-chloride dual-ion battery (DIB) with an efficient chloride–hypochlorite couple with an E10–E1/2 potential gap of about 0.94 V and OCP of 1.44 compared to an ORR–OER couple with an E10–E1/2 potential gap of about 1.07 V and OCP of 1.35 V at pH 10 with a comparatively efficient stable fast charge–discharge with a peak power reaching a maximum value of 120 mW under specified conditions. The catalyst is able to selectively catalyze the chloride oxidation (ClOR) and hypochlorite reduction (ClRR) reaction, which inherent the DIBs with better charge–discharge cycle efficiency. Arrhenius activation energy analysis for the catalyst unveils the reason behind the trend in the catalytic selectivity. DFT calculations reveal the advantage of stabilizing such HEAs over carbon systems and its effect on handling the intermediates and the improvement in the selectivity of ClOR/ClRR over OER/ORR on high-entropy alloy heterostructures.