Comparing the Performance of Nb2O5 Composites with Reduced Graphene Oxide and Amorphous Carbon in Li- and Na-Ion Electrochemical Storage Devices

Abstract

Two-dimensional (2D) reduced graphene oxide (rGO) is often combined with metal oxides for energy-storage applications, owing to its unique properties. Here, we compare the electrochemical performance of Nb2O5-rGO and amorphous carbon-coated-Nb2O5 composites, synthesized in similar conditions. The composite made of Nb2O5 and amorphous carbon (using 1,3,5-triphenylbenzene as carbon source) outperforms the Nb2O5-rGO counterpart as a high rate anode electrode material in Li-ion and Na-ion half-cells and hybrid supercapacitors, delivering specific capacities of 134 mAh g−1 at 25 C against 98 mAh g−1 for the rGO-based composite (in Li electrolyte) and 125 mAh g−1 at 20 C against 98 mAh g−1 (in Na electrolyte). The organic molecules, which are the precursor of the amorphous carbon, control the size and coat the metal oxide particles more efficiently, leading to more extensive carbon-oxide contacts, which benefits the energy-storage performance.