Solvothermal preparation of zinc cobaltite mesoporous microspheres for high-performance electrochemical supercapacitors

ZnCo2O4 mesoporous microspheres (ZMMs) assembled by a huge amount of nanoparticles (NPs) were solvothermally synthesized with a subsequent annealing treatment in air. These ZMMs possess a BET specific surface area of 7.7 m(2)g(-1) and an average pore size of 12.8 nm, respectively. The electrochemical performances of the ZMMs-modified electrode were evaluated by using a typical three-electrode electrochemical system in 2 M of KOH aqueous electrolyte. The ZMMs-based electrode delivered high specific capacitance of 588 Fg(-1) at 1 Ag-1 and good rate capability of about 84% with the current densities increasing from 1 to 15 Ag-1. Besides, the electrode exhibited an outstanding long-term cycling stability during a 5000-cycle charge-discharge process with both 68.4% capacitance retention and 99.7% Coulombic efficiency at a high current density of 8 Ag-1. Such good electrochemical performances were probably attributed to its unique porous structure providing many active reaction sites, fast ion and electron transfer, and good strain accommodation as well. The excellently electrochemical properties make it one of the most promising electrode materials for advanced electrochemical supercapacitors. (C) 2018 Elsevier B.V. All rights reserved.