Terbium-based phosphine compound: A long-term cycling life material for high-performance supercapacitor

Herein, a one-step route has been developed for synthesizing terbium-phosphine (Tb-(Ph)3P) compound, which exhibited an excellent rate capability and an outstanding long cycling stability. The highest specific capacitance of 1866 F g-1 has been obtained at 2 A/g in 6 M KOH, and the capacitance retention of 81.02% has also been achieved at 10 A/g after 30,000 cycles, resulted in a maximum energy density of 93.3 W h kg-1 and a maximum power density of 6.04 kW kg-1. Such an excellent performance might be attributed to the insolvability and intrinsic characteristics of the Tb-based phosphine complexes, which provided abundant active sites for the charge storage and conductive networks for electron transport. Moreover, a flexible quasi-solid-state asymmetric supercapacitor composed of Tb-(Ph)3P and active carbon has been fabricated, and a specific capacitance of 275 mF cm-2 at a current density of 2 mA cm-2, and a capacitance retention of 100% after 10,000 cycles at 10 mA cm-2 have been respectively achieved, exhibiting an excellent electrochemical property. Thus, the present work might provide a new strategy for designing new metal-organic complex materials and their applications in energy storage devices.