High entropy compounds for electrochemical energy storage

Abstract

High entropy compounds (HECs) are a new type of multi-element material. They overcome the limitations of traditional energy storage materials. HECs achieve this through three key features: high entropy effect, lattice distortion, and element synergy. Their structures contain several main elements mixed in nearly equal amounts. This mixture creates a stable, single-phase material. This stable structure stops harmful phases from forming. In the synthesis, the solid-phase method, the wet chemical method and the gas-phase method are adapted to different morphologies and large-scale needs, respectively. At the application level, as a lithium electrode, the specific capacity can be increased, the volume expansion can be suppressed, and the specific capacitance can be increased by multi-element redox in supercapacitors, and when a high entropy compound is used as a solid fuel cell cathode, the oxygen ion conductivity optimization can achieve a theoretical energy conversion efficiency of 85%. In the future, it is necessary to focus on the research on synthesis process optimization and the structure–activity relationship to expand its application potential in flexible devices and multi-scenario energy systems.