Low-crystalline β-Ni(OH)2 nanosheets on nickel foam with enhanced areal capacitance for supercapacitor applications

β-Ni(OH)2 is considered a potential candidate of supercapacitor electrode material due to its high theoretical capacitance and cost efficiency. In order for β-Ni(OH)2 electrode to achieve high areal capacitances, we report effective fabrication of high mass loading low-crystalline β-Ni(OH)2 on nickel foam through the acid-etching formation of Ni3(PO4)2 precursor and the subsequent electrochemical activation. The heavily-loaded (13.5 mg cm−2), binder-free β-Ni(OH)2 electrode presents a high areal capacitance of 15.31F cm−2 (1134F g−1) at current density of 30 mA cm−2 (2.22 A g−1) and has a capacitance retention of 85% after 10,000 cycles at a high current density of 110 mA cm−2 (7.41 A g−1). Besides, the assembled hybrid supercapacitors can deliver an areal capacitance of 2.59F cm−2 at 20 mA cm−2 with a maximum energy density of 0.49 mWh cm−2 (2.45 mWh cm−3). This work provides a certain reference for exploring a low-cost and large-scale method of material synthesis at room temperature for high mass loading and capacitance in the future application.