A battery-type cathode with RuO2 modified Ni11(HPO3)8(OH)6 for asymmetric supercapacitors

Phosphates are a kind of promising electrode materials because they can provide numerous cavities and several reaction sites to be favored for storing anions and cations. However, the widespread application of phosphates are limited by their intrinsically low electronic conductivity. RuO 2 /hydrated RuO 2 exhibits high conductivity and excellent electrochemical properties. Reducing its dosage and increasing its specific surface area are the research concerns. Combining less RuO 2 to Nickel phosphate (NiP) is expected to improve the electrochemical performance. RuO 2 -modified NiP (NiP-RuO 2 ) electrode material is synthesized by a one-step hydrothermal reaction and its structural morphology and capacitive properties are investigated. The results indicate that NiP-RuO 2 electrode consists of hydrated RuO 2 and Ni 11 (HPO 3 ) 8 (OH) 6 , and exhibits excellent battery-type electrochemical supercapacitor performance with a specific capacity of 878.06 C/g at 1 A/g. According to density functional theory (DFT) analysis, Ru-doped Ni 11 (HPO 3 ) 8 (OH) 6 has a narrower forbidden band width and higher conductivity than Ni 11 (HPO 3 ) 8 (OH) 6 . Furthermore, the asymmetric supercapacitor (ASC) assembled by NiP-RuO 2 /NF and activated carbon (AC) electrode achieves a high energy density (43.58 Wh/kg) at a power density of 923.47 W/kg. When two ASC devices are connected in series, ten light-emitting diodes (LEDs) can be illuminated for ten minutes.