Controllable Synthesis of NiCo LDH Nanosheets for Fabrication of High‐Performance Supercapacitor Electrodes

Abstract A unipolar pulse electrodeposition method was employed to controllably synthesize nanosheet type NiCo LDH. The effect of concentration rate of Ni(NO 3 ) 2 /Co(NO 3 ) 2 preparation solution on crystalline structure, morphology and supercapacitive performance was investigated systematically. Experimental found that the morphology and composition of NiCo LDH was highly depend on the Ni 2+ /Co 2+ molar ratios of preparation solution; and the obtained Ni 0.76 Co 0.24 LDH materials showed small nanosheet size and uniform distribution on carbon fiber electrode. Ni 0.76 Co 0.24 LDH electrode was evaluated for supercapacitor application, which revealed a high specific capacitances of 2189.8 and 1908.8 F g −1 at the current density of 1 and 30 A g −1 respectively and a good cycle stability, retaining 70.3 % of the initial capacitance after 20000 charge and discharge cycles at 50 A g −1 . Moreover, the Ni 0.76 Co 0.24 LDH electrode exhibits a high energy density of 76 Wh Kg −1 at a power density of 250 W Kg −1 and a high power density of 7500 W Kg −1 at energy density of 66 Wh Kg −1 . The as‐prepared Ni 0.76 Co 0.24 LDH as positive electrode for asymmetric supercapacitor exhibits excellent energy density of 4.1 Wh Kg ‐1 at a power density of 4000 W Kg ‐1