Ni-based chromite spinel for high-performance supercapacitors

Abstract

NiCr₂O₄ has been prepared through the easy precipitation reaction of Ni²⁺ and Cr³⁺ (1 : 2 mol ratio) in aqueous NH₃ followed by annealing at a high temperature. This is the first time that NiCr₂O₄ has been used as an electrode material for a supercapacitor. As expected, the NiCr₂O₄ exhibits good supercapacitive performance: at a current density of 0.6 A g⁻¹, the specific capacitances of NiCr₂O₄ in the three-electrode and two-electrode setups are 422 and 187 F g⁻¹, respectively; the energy density for the NiCr₂O₄ symmetric device reaches 6.5 W h kg⁻¹ at a power density of 3000 W kg⁻¹; and about 80% of the capacitance is retained after 2000 charge/discharge cycles. Therefore, research on NiCr₂O₄ as a supercapacitor material is necessary.