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.