3D hierarchical Co-Al layered double hydroxides with long- term stabilities and high rate performances in supercapacitors

Three-dimensional (3D) flower-like Co-Al layered double hydroxide (Co-Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co-Al-LDHs was improved. When used in supercapacitors, the obtained Co-Al-LDHs deliver a high specific capacitance of 838 F g^-1 at a current density of 1 A g^-1 and excellent rate performance (753 F g^-1 at 30 A g^-1 and 677 F g^-1at 100 A g_-1), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 A g^-1. This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.