Tuning the phase composition in polymorphic Nb2O5 nanoplates for rapid and stable lithium ion storage

By using the intrinsic polymorphism nature of Nb2O5 material, we employ three typical Nb2O5 phases (orthorhombic (T), tetragonal (M) and monoclinic (H) phases) in a single material, and optimize the phase composition to form nanodomains, which are achieved by carefully adjusting the calcination parameters. The resulting sponge-like Nb2O5 nanoplate anodes exhibit attractive rate performance and cycle stability. Specifically, the optimized electrode shows a reversible capacity of 321 mAh g−1 at 1 C (1 C = 200 mA g−1) after 200 cycles. At a high current density of 10 C, the electrode delivers a reversible capacity of 152 mAh g−1. Long term durability tests show that the electrode performs an excellent cycling performance at a current density of 5 C over 1000 cycles with a capacity loss of 0.06 mAh g−1 per cycle. The excellent lithium storage properties are due to the unique multiple phases and nanoscale interface inside the electrode, which facilitate the storing of more ions and the rapid ion transportation during the charging/discharging process. The proposed electrode design strategy provides an alternative route to develop advanced electrodes for energy storage.