Construction of MnSe2/CoSe2/reduced graphene oxide composites with enhanced electrochemical performance as the battery-like electrode for hybrid supercapacitors

Abstract Currently, bimetallic transition metal selenides have allured great attention as battery-like electrode materials for hybrid supercapacitors on account of their lower band gap and preferable electrical conductivity. Herein, a series of MnSe2/CoSe2 (MCSe) with nanosheets structure were rationally synthesized on rGO-coated Ni foam (MCSe/rGO) by employing the simple two-pot hydrothermal strategy with manganese cobalt oxide as precursor followed by a selenization treatment with various selenization times. The time-dependent experiments indicate that the selenization time plays an important role in forming the morphologies and the electrochemical behaviors of MCSe/rGO composites. Remarkably, the MCSe/rGO composite with the optimal selenization time (MCSe-3 h/rGO) exhibits an excellent specific capacity of 1138 C g−1 at 1 A g−1, predominant rate performance of 80% even at 50 A g−1 along with exceptional cycling behavior of 98.5% through 5000 cycles. Additionally, by integrating the as-obtained MCSe-3 h/rGO as anode with activated carbon (AC) as cathode, a hybrid supercapacitor (HSC) was constructed and performed a desirable energy density of 45.8 W h kg−1 at the power density of 853.1 W kg−1 and 100% capacity retention over 7000 cycles. The remarkable electrochemical properties show that the MCSe-3 h/rGO composite as a battery-like electrode material holds substantial potential for energy storage applications.