Facile Preparation and Performances of Ni, Co, and Al Layered Double Hydroxides for Application in High-Performance Asymmetric Supercapacitors

Layered double hydroxides (LDHs) are widely studied as electrode materials of supercapacitors (SCs) owing to their specific composition and morphology and plentiful electrochemically active sites. Especially, nickel cobalt hydroxides can achieve an outstanding electrochemical performance as electrode materials of SCs because of the synergy effect between Ni and Co. Herein, ternary LDHs including Ni, Co, and Al (NiCo2Al x -LDHs) with different stoichiometric ratios are synthesized by a facile method to further research the influences of Al on the morphology and electrochemical performances of LDHs. Results show that the NiCo2Al0.5-LDHs electrode delivers a high specific capacitance (1260 F g–1 at 0.5 A g–1) and an excellent capacitance retention (81.5% of initial capacitance). Besides, an asymmetric supercapacitor (ASC) assembled with a NiCo2Al0.5-LDHs cathode and an activated carbon (AC) anode (NiCo2Al0.5-LDHs//AC ASC) exhibits a high energy density of 39 Wh kg–1 with remarkable cycling stability (91.7% of initial capacitance retention after 6000 cycles at 5 A g–1).