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

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.