Carbon coated Nb2O5 nanosheets via dopamine-induced phase transition for high-rate lithium-ion battery

Nb2O5 has attracted great attention as a promising anode material for lithium-ion batteries (LIBs) due to relatively high rate-capacity, fast charge/discharge ability and excellent cycling performance. Unfortunately, the poor electron conductivity restricts its application. In this work, we report an effective method to synthesize large-size Nb2O5 nanosheets wrapped within carbon layer (denoted as Nb2O5@C) by using layered K4Nb6O17 (abbreviated as KN) as the templates of dopamine polymerization, followed by the carbonization. It is demonstrated that dopamine not only serves as the carbon source, but also promotes the phase transition and the morphology transition. The obtained Nb2O5@C nanosheets with enhanced electron conductivity deliver outstanding rate capability (485, 372, 304, 267 and 232 mAh g−1 at the current density of 0.1, 0.2, 0.5, 1 and 2 A g−1, respectively) with a low capacity fading-rate of about 0.02% after 1000 cycles at 2 A g−1. This work may provide a helpful strategy in developing the high-rate lithium-ion storage applications for other related materials.