High-Energy-Density Supercapacitors from Dual Pseudocapacitive Nanoelectrodes

Supercapacitors feature high power densities but low energy densities. To further improve the energy densities of supercapacitors, it is important to design and synthesize new electrode materials. The performance match of the used anode and cathode is also required for the construction of supercapacitors with both high power densities and energy densities. In this work, two redox-active electrode materials are synthesized: bimetallic Ni–Co hydroxide/oxide hydroxide nanosheets-coated holey reduced graphene oxide (hrGO) and rGO-supported Fe2O3 nanorods. They are further employed as the cathode and the anode to construct a dual pseudocapacitor, respectively. After matching the performance of two electrodes, the as-assembled supercapacitor device features a cell voltage of 1.6 V. It exhibits an energy density of 91.1 Wh kg–1 at a power density of 800.0 W kg–1 and a long cycling life. Its power density can reach 24008.1 W kg–1 when a current density of 30 A g–1 is applied. Therefore, this kind of dual pseudocapacitor is an efficient energy storage device and can be utilized as a promising energy supplier for different applications.