Synthesis of Li2Ni2(MoO4)3 as a high-performance positive electrode for asymmetric supercapacitors

Abstract

A NASICON-type compound, Li₂Ni₂(MoO₄)₃ was successfully synthesized via a combustion method. The as-synthesized Li₂Ni₂(MoO₄)₃ is fiber-like grains with an average length of 1–2 μm. As an electrode for pseudocapacitors, in 2 M LiOH, its specific capacitance reached 1137 F g⁻¹ and 717 F g⁻¹ at current density of 1 A g⁻¹ and 20 A g⁻¹ respectively, exhibiting 63% capacity retention. Moreover, in asymmetric supercapacitors with an activated carbon electrode as the negative electrode, the energy density of 36.5 W h kg⁻¹ was obtained at the average power density of 420 W kg⁻¹. The fabricated asymmetric supercapacitor also exhibited good electrochemical stability, specifically, the specific capacitance was retained at 68% of the initial value even after 10 000 cycles at 2 A g⁻¹. These observations suggest that the prepared Li₂Ni₂(MoO₄)₃ is a prospective candidate for high-performance supercapacitors.