Spectator-metal-ion-guided redox-dominant cobalt oxyhydroxide as a high-performance supercapacitor.

The ability of spectator metal ions such as vanadium to enhance the electrochemical performance of supercapacitors has been explained. Vanadium-incorporated CoO(OH) combined with NiMn-layered double hydroxide (LDH) yields a specific capacitance of 1700 F g -1 at 1 A g -1 with 96% retention after 5000 cycles. The assembled asymmetric supercapacitor exhibits an energy density of 45.93 W h Kg -1 and a power density of 752 W kg -1 @1 A g -1 .