Synthesis of Li 2 Ni 2 (MoO 4) 3 as a high-performance positive electrode for asymmetric supercapacitors

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.