Defects engineering of Fe2O3@Sn2O3 nanosheet arrays for high-performance hybrid supercapacitor

Abstract Developing new-type electrode materials with high surface area, stable microstructure and high performance is important to global sustainability. Herein, we successfully fabricate an oxygen-deficient Fe2O3@Sn2O3 nanocomposite composed of Fe2O3 and Sn2O3 nanosheet-arrays on Ni foam. Benefiting from this kind of binder-free nanosheet-arrays microstructure and the oxygen vacancy, the electrode oxygen-deficient Fe2O3@Sn2O3 (VO-Fe2O3@Sn2O3) nanocomposite possesses an excellent specific capacity (694.8 C g−1) at a current density of 1 mA cm−2, superior rate capability (it still maintains 477.6 C g−1 at 10 mA cm−2), and long cycle stability. The hybrid supercapacitor, assembled with VO-Fe2O3@Sn2O3 nanosheet arrays as the cathode, active carbon (AC) as the anode and polyvinyl alcohol (PVA)/KOH as the gel electrolyte, delivers a high energy density of 39.1 W h kg−1 at a power density of 1.28 kW kg−1 and a retention rate of 81.4% even after 10,000 cycles at 1.6 A g−1. Furthermore, two assembled devices in series can power a commercial LED for a long time.