Boosting Specific Capacity for Supercapattery by <i>In Situ</i> Formation of Amorphous Ni–Co–Borate on MOF-Derived Ni–Co–LDH Nanosheet Array

Abstract

Amorphous materials have great potential for storing energy owing to their porous structure, high stability, and fast charging rate. Also, ingeniously incorporating amorphous materials into crystalline materials through surface amorphization strategy can construct excellent electrodes for supercapattery. Herein, Ni–Co-layered double hydroxide/Ni–Co–borate (Ni–Co–LDH/Ni–Co–Bi) composite is synthesized by in situ formation of amorphous Ni–Co–borate on metal–organic frameworks (MOFs)-derived Ni–Co–LDH nanosheet array. The adherent amorphous Ni–Co–borate can modulate the crystalline and electronic structures of Ni–Co–LDH, which provide an effective path for electron transfer and boosts the kinetics of redox reaction. Consequently, the crystalline/amorphous Ni–Co–LDH/Ni–Co–Bi composite shows a high specific capacity of 891 C/g at 1 A/g. When used as a battery-type electrode to assemble supercapattery, it displays a maximum energy density of 62.8 Wh/kg at a power density of 800 W/kg and fine stability (∼81% capacity retention after 5000 cycles). In addition, an all-solid-state supercapattery can lighten a white light-emitting diode (LED) for 60 s, demonstrating potential practical applications of Ni–Co–LDH/Ni–Co–Bi. Hence, it is a very promising study to shed substantial light on inspiring crystalline/amorphous materials for energy storage.