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 (NiCoO 2  ）heterostructure for enhanced supercapacitors (SCs). Benefiting from the synergy effect between the porous GaN network as a highly conductive skeleton and the NiCoO 2 with massive active sites. The GaN/NiCoO 2 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/NiCoO 2 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.