Seed-assisted smart construction of high mass loading Ni–Co–Mn hydroxide nanoflakes for supercapacitor applications

Abstract

Smartly designed nanoarchitectures with effective hybridization of transition metal oxides/hydroxides are promising to realize high performance electrodes for energy storage devices. To promote the applications of high-power supercapacitors, a seed-assisted method is firstly applied to prepare mesoporous Ni–Co–Mn hydroxide nanoflakes (NCMH) on nickel foam with practical mass loadings (higher than 5 mg cm⁻²). Further mechanism study reveals that the Ni(OH)₂ nanorod arrays, which are firstly prepared by a hydrothermal process, serve as seeds for the successful deposition of NCMH nanoflakes. Through this convenient and cost effective method, this design results in a more orderly spatial distribution, lower intrinsic resistance and shorter electron transport pathways. The proof-of-concept application of NCMH as a binder-free supercapacitor electrode reveals an impressive specific capacity of 1043.1 μA h cm⁻² at a high mass loading of 5.2 mg cm⁻². The NCMH//activated carbon asymmetric device delivered a maximum energy density of 55.42 W h kg⁻¹ at a power density of 750 W kg⁻¹, exhibiting great potential as an energy storage device and shedding light on the structural design of nanomaterials.