Hydrolysis of metal-organic framework towards three-dimensional nickel cobalt-layered double hydroxide for high performance supercapacitors

Abstract

Layered double hydroxide (LDH) is commonly employed as supercapacitor electrode due to its high theoretical and experimental capacitance, but limited by its easily agglomerated structure. Herein, a three-dimensional nickel cobalt-layered double hydroxide on carbon fiber cloth (NiCo-LDH/CFC) is synthesized via an in-situ hydrolysis of Co-based metal organic framework array (Co-MOF) for supercapacitors. Both the metal sites and overall morphology of Co-MOF are well maintained inner NiCo-LDH/CFC, providing sufficient active sites and rapid diffusion kinetics for charge storage. Consequently, an optimal specific capacitance of 2685 F g−1 (1074 C g−1) is achieved for NiCo-LDH/CFC electrode, higher than that of powdered NiCo-LDH (1352 F g−1 or 540.8 C g−1). Moreover, a hybrid supercapacitor is assembled with NiCo-LDH/CFC as positive electrode and active carbon as negative electrode. The hybrid device exhibits a high energy density of 64.9 Wh kg−1, a maximum power density of 16.9 kW kg−1, and long cycling stability (82.7% capacitance retention after 3000 cycles). These results indicate the great potential of in-situ hydrolysis of MOFs for high performance energy storage electrode materials.