Rapid redox kinetics in uniform sandwich-structured mesoporous Nb2O5/graphene/mesoporous Nb2O5 nanosheets for high-performance sodium-ion supercapacitors

Mesoporous Nb2O5/graphene/mesoporous Nb2O5 nanosheets where Nb2O5 layers are constructed by several nanometer-sized Nb2O5 particles are prepared for high-rate Na-ion storage. Electrochemical analysis indicated the structural and compositional features-derived rapid redox kinetics are the important origins. Coupling with an activated carbon cathode, a full Na-ion hybrid ESC provided both high energy and power densities (56.1 and 9.7 Wh Kg−1 under 120 and 7200 W Kg−1, respectively) with a stable capacity with high retention of ca. 89% at 1 A g−1.217