Hierarchical self-supported Ni(OH)2@Ni12P5 for supercapacitor electrodes with ultra-high area ratio capacitance

Transition metal hydroxides, due to their low cost and high theoretical capacity, are promising candidates for supercapacitors. However, the lower conductivity of hydroxides usually results in devices exhibiting poor specific capacity. Here, Ni(OH)2@Ni12P5 electrodes are designed and prepared, showing great potential for applications. This composite electrode, prepared by simple phosphating treatment and electrodeposition. Compared with the Ni(OH)2 prepared by direct deposition, this rationally designed electrode exhibits more excellent electrochemical properties. The prepared Ni(OH)2@Ni12P5 electrode exhibits a good area specific capacitance of 15.89 F•cm−2 at a current density of 10 mA•cm−2, which is 2.93 times higher than that of the Ni(OH)2 electrode (5.43 F•cm−2). In addition, the assembled Ni(OH)2@Ni12P5//AC asymmetric supercapacitor exhibits an energy density of 0.38 mWh•cm−2 at a power density of 8.00 mW•cm−2 . Therefore, this work provides a new strategy for the synthesis of high-performance supercapacitor electrodes.