High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes

A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g^-1 at a current density of 1 A g^-1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g^-1 at a current density of 2 A g^-1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm^-2 at 2 mA cm^-2 and a high energy density of 0.71 mWh cm^-2 at a power density of 17.05 mW cm^-2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge-discharge cycles).