Emerging high-entropy compounds for electrochemical energy storage and conversion

As a new member in high-entropy materials family developed after high-entropy alloys, high-entropy compounds (HECs) are of particular interest owing to the combination of superiorities from high entropy and cocktail effects. The discovery of HECs indeed opens up a new frontier in the field of energy storage and conversion. This article provides a comprehensive review of the new frontiers on HECs for energy-related application. It begins with the fundamentals of HECs, with an emphasis on thermodynamic and structural features, and characterizations of HECs. Discussion is then made on the synthetic strategies of component optimization and structure engineering for the developing various HECs. Thereafter, the application of HECs particularly in electrodes for rechargeable batteries and supercapacitors, electrolytes for batteries, electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR) are highlighted. Finally, this review is concluded with an outlook of future research on HECs, major challenges to be addressed and possible solutions.