Facile synthesis of Ni-coated Ni₂P for supercapacitor applications

Ni₂P particles are coated homogenously with amorphous Ni by an electroless plating process. The Ni coating exhibits a nanoflake morphology and has 20–30 nm in thickness after plating for 10 min. As electrochemical capacitor materials, the pseudocapacitor behaviors are investigated by cyclic voltammograms and galvanostatic charge–discharge tests in 2 M LiOH. The Ni-coated Ni₂P delivers high specific capacitances of 581 F g⁻¹ at 1 A g⁻¹ and 464 F g⁻¹ at 40 A g⁻¹, respectively, and also exhibits superior cycling performance. The specific capacitance can achieve a maximum of 1115 F g⁻¹ at 2 A g⁻¹, which can still maintain 1029 F g⁻¹ (92.3% capacity retention) after 3000 cycles. The enhanced pseudocapacitive performances are mainly attributed to its flake-like Ni coating which can provide fast ion and electron transfer and large amounts of active sites.