• High-entropy and multicomponent-doped materials offer enhanced structural stability and tunable electronic, ionic, and catalytic functionalities for energy applications.
• The special issue compiles 21 articles covering solid oxide cells, hydrogen storage, batteries, and capacitors, showcasing significant performance improvements.
• Notable advances include a high-entropy perovskite air electrode achieving a peak power density of 1.18 W·cm−2 and an electrolysis current density of −0.52 A·cm−2 at 700°C.
• The collection provides a comprehensive reference and inspires further exploration of the vast compositional and functional space of HEMs and multicomponent materials.