Transition metal sulfide nanostructures: synthesis and application in metal-air batteries

Owing to great energy density, eco-friendliness, safety and security, and cost-effectiveness, rechargeable metal-air batteries (MABs) have engrossed substantial devotion. The MABs signify one of the most feasible forthcoming alternatives to powering electric vehicles (EVs) and smart-grid energy storage. The progress of MABs has offered a solution benefitting from its much higher theoretical energy density than that of lithium-ion batteries (LIB). However, certain technical difficulties allied with metal-air batteries include sluggish electrochemical oxygen reaction kinetics that has yet to be fixed. The transition single metal and mixed metals sulfides (TMS) nanostructures have validated an advanced electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance, due to their higher electronic conductivity and fast-charge transfer kinetics. The bifunctional electrocatalytic act of the TMSs can be enhanced by altering the electronic configuration, double layer structure and interface, valence state, and vacancies. In this minireview, the preparation, properties, and testing of electrode components of transition metal sulfides (TMS) nanomaterials towards different types of metal-air batteries (aqueous and non-aqueous), the fundamentals, configuration of battery, choice of electrode materials, electrolyte, and separator, current challenges as well as perspectives of the design of high-performance MABs are also discussed based on the existing execution.