Preparation of Nb2O5 with an air filter-like structure and its excellent electrochemical performance in supercapacitors

A Nb2O5 compound with a structure similar to an air filter (AF-Nb2O5) was synthesized using a hydrothermal method, and further calcined to form a product that was designated CAF-Nb2O5. The morphology and microstructure of the AF-Nb2O5 and CAF-Nb2O5 were examined using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The AF-Nb2O5 and CAF-Nb2O5 exhibited similar filter-like structures, which consisted of regular pores and ordered networks. The CAF-Nb2O5 exhibited a high specific capacitance of 258 F g−1 at a current density of 0.5 A g−1, an excellent rate capacity of 172 F g−1 at the high current density of 5 A g−1 and an impressive capacitance retention of 90.5% after 5000 cycles at the current density of 2 A g−1. The CAF-Nb2O5 exhibited excellent electrochemical properties by virtue of its abundance of ion channels and its filter-like structure.