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  ï¼‰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.

Construction of Novel Bimetallic Oxyphosphide as Advanced Anode for Potassium Ion Hybrid Capacitor.

Potassium ion hybrid capacitors (PIHCs) have attracted considerable interest due to their low cost, competitive power/energy densities, and ultra-long lifespan. However, the more sluggish insertion kinetics of battery-type anodes than capacitor-type cathodes in PIHCs seriously limits their practical application. Therefore, developing advanced anodes with high capacitor and suitable K+ intercalation is imperative and significant. A novel core-shell structure of NiCo oxide/NiCo oxyphosphide (NCOP) nanowires are designed and constructed in this study via efficient and facile strategy. Combining the merits of the core-shell structure and the massive active sites in the oxyphosphide layer, the as-prepared NCOP composites manifest highly reversible capacitors and outstanding rate capability. Meanwhile, the insertion and conversion potassium storage mechanisms of the NCOP are successfully revealed through in situ X-ray diffraction and density functional theory calculations, respectively. Furthermore, the PIHC was assembled with NCOP anode and borocarbonitride cathode, which displays a large energy density and high-power density, along with an exceptional capacity retention of ≈90% over 10 000 cycles at 1.0 A g-1 . This work provides the anion regulation strategy for modifying the transition metal oxide and constructing the advancing electrode materials for next-generation energy storage and beyond.