Two-dimensional layered magnesium–cobalt hydroxide crochet structure for high rate and long stable supercapacitor application

Abstract

Pseudocapacitors with nickel/cobalt hydroxide-based electrodes show promises energy storage devices, because they are economical and safe, but cycle stability and high current rate capability have not been achieved. We shed light on how magnesium in double-layered hydroxides serves as a supercapacitor electrode in optimal environments. Here we show the high rate capability and long-term stability of layered magnesium–cobalt double hydroxide (L-MCH) electrodes, which is superior to existing electrodes. The pseudocapacitor made with Mg²⁺ and Co²⁺ double hydroxide as active materials, does not have an intricate fabrication process. The L-MCH pseudocapacitor has a specific capacitance comparable to most double hydroxide-based materials and capacity retention greater than 107% over 10,000 cycles, which is in line with commercial devices. Our proposed method also offers a much faster and reliable route for electrode fabrication, which could result in the development of a new generation of supercapacitors, batteries and hybrid devices.