Hierarchical Ni-Co-Mn hydroxide hollow architectures as high-performance electrodes for electrochemical energy storage

Abstract

In this study, hierarchical Ni-Co-Mn hydroxide hollow architectures were successfully achieved via an etching process. We first performed the synthesis of NiCoMn-glycerate solid spheres via a solvothermal route, and then NiCoMn-glycerate as the template was etched to convert into hierarchical Ni-Co-Mn hydroxide hollow architectures in the mixed solvents of water and 1-methyl-2-pyrrolidone. Hollow architectures and high surface area enabled Ni-Co-Mn hydroxide to manifest a specific capacitance of 1626 F g^-1 at 3.0 A g^-1, and it remained as large as 1380 F g^-1 even at 3.0 A g^-1. The Ni-Co-Mn hydroxide electrodes also displayed notable cycle performance with a decline of 1.6% over 5000 cycles at 12 A g^-1. Moreover, an asymmetric supercapacitor assembled with this electrode exhibited an energy density of 44.4 W h kg^-1 at 1650 W kg^-1 and 28.5 W h kg^-1 at 12 374 W kg^-1. These attractive results demonstrate that hierarchical Ni-Co-Mn hydroxide hollow architectures have broad application prospects in supercapacitors.