Nb2O5/graphene nanocomposites for electrochemical energy storage

The development of electrode materials for energy storage, with high energy and power densities along with good cyclic stability, still remains a big challenge. Here we report the synthesis of Nb2O5/graphene nanocomposites, through a simple hydrothermal method, with Nb2O5 nanoparticles anchored on reduced graphene oxide (RGO) sheets. The fabricated Nb2O5/graphene electrodes exhibited an excellent electrochemical performance when studied as anodes for lithium-ion batteries, with a superior reversible capacity and high power capability (192 mA h g(-1) under 0.1C rate over 50 cycles). Signature curve studies showed high power capability of the Nb2O5/graphene electrode with similar to 80% of the total capacity retained at 16C rate compared to similar to 30% retention for pristine Nb2O5 nanoparticles. To achieve further improvement in energy density and power capability, Li-ion hybrid electrochemical capacitors (Li-HECs) were fabricated with the Nb2O5/graphene nanocomposite as the anode and rice husk-derived activated porous carbon as the cathode, in non-aqueous electrolyte. The Li-HECs showed enhanced electrochemical performance with high energy density of 30 W h kg(-1), at a specific power density of 500 W kg(-1). The Nb2O5/graphene nanocomposites show promising results and hence have great potential for application in efficient electrochemical energy storage devices.