Gallium Nitride Based Electrode for High‐Temperature Supercapacitors

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. The porous GaN/NiCoO2 heterostructure is designed as an advanced electrode and assembled SCs combine with ionic liquids electrolytes, and the device displays excellent performance at 130 °C. The theoretical calculation further explained that the reason for the energy storage enhancement of the GaN/NiCoO2 is due to the presence of the built‐in electric fields.