Gallium Nitride Based Electrode for High‐Temperature Supercapacitors

Abstract Gallium nitride (GaN) single crystal, as the representative of wide‐band semiconductors, has great prospects for high‐temperature energy storage, of its splendid power output, robust temperature stability, and superior carrier mobility. Nonetheless, it is an essential challenge for GaN‐based devices to improve energy storage. Herein, an innovative strategy is proposed by constructing GaN/Nickel cobalt oxygen (NiCoO₂ ）heterostructure for enhanced supercapacitors (SCs). Benefiting from the synergy effect between the porous GaN network as a highly conductive skeleton and the NiCoO₂ with massive active sites. The GaN/NiCoO₂ heterostructure‐based SCs with ion liquids electrolyte are assembled and delivered an impressive energy density of 15.2 µWh cm⁻² and power density, as well as superior service life at 130 °C. The theoretical calculation further explains that the reason for the energy storage enhancement of the GaN/NiCoO₂ is due to the presence of the built‐in electric fields. This work offers a novel perspective for meeting the practical application of GaN‐based energy storage devices with exceptional performance capable of operation under high‐temperature environments.