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

Abstract

• Tb-based phosphine compound has first been used as an electrode of supercapacitor. • The highest capacitance of 1866 F g −1 at 2 A/g can be obtained. • 81.02% of initial capacitance can be remained after 30,000 cycles at 10 A/g . Herein, a one-step route has been developed for synthesizing terbium-phosphine (Tb-(Ph) 3 P) 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) 3 P 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.