A novel and facile step-by-step hydrothermal fabrication of peony-like Ni0.4Co0.6(OH)2 supported on carbon fiber cloth as flexible electrodes for advanced electrochemical energy storage

•This is the first investigation on the Ni0.4Co0.6(OH)2/CFC electrode material.•This Ni0.4Co0.6(OH)2/CFC exhibited a capacitance of 1816 F g−1 at 1.0 A g−1.•The capacitance retention is 98.3% after 5000 charge/discharge cycles.•The supercapacitor remained stable under flat, folded, twisted and rolled states.

Nickel/Cobalt double hydroxide has attracted increasing attention as promising electrode material in supercapacitor field, but its poor adhesion in most conductive substrates largely thwarts the capacitance and cycling stability performance. In this work, an effective strategy was developed to synthesis Ni0.4Co0.6(OH)2 onto carbon fiber cloth (CFC) and obtained a flexible peony-like electrode (Ni0.4Co0.6(OH)2/CFC) by a simple step-by-step hydrothermal method without any adscititious alkali source and oxidant. Electrochemical studies showed that this type of Ni0.4Co0.6(OH)2/CFC exhibited an extraordinary capacitance of 1816 F g−1 (605 F cm−2) at the current density of 1.0 A g−1 and excellent cycling stability with capacitance retention of 98.3% after 5000 charge/discharge cycles. After assembled to be a symmetric flexible solid supercapacitor, its electrochemical performances remained stability under flat, folded, twisted and rolled states. The remarkable electrochemical and flexible properties of Ni0.4Co0.6(OH)2/CFC developed in this study are obviously superior to those previously reported Ni0.4Co0.6(OH)2-based supercapacitors.