Pine needle β-Co(OH)2 grown on Ni foam substrate for high specific capacitance and good cycling stability as advanced electrochemical pseudocapacitor materials

• 1D pine needle β-Co(OH)2 directly grown on Ni foam substrate was synthesized.
• 3D pine needle network structure with more active points was assembled.
• The β-Co(OH)2/NF exhibits high specific capacitance and excellent cycle stability.
• Pine needle β-Co(OH)2/NF with low charge-transfer resistance was observed.

Pine needle β-Co(OH)2 grown on Ni foam (β-Co(OH)2/NF) substrate was fabricated via a simple hydrothermal process for improved electrochemical properties. The sample has been characterized by FTIR, XRD, TG, SEM, TEM, cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance study. It exhibits high specific capacitance of 1215 F/g and 790 F/g at current density of 5 and 50 A/g, respectively. The capacitance can retain about 91.4% after 1000 charge-discharge cycles at a current density of 50 A/g. The β-Co(OH)2/NF has high specific capacitance and long cycle stability, which makes it suitable for supercapacitor application.