Controlled synthesis of pure-phase metastable tetragonal Nb2O5 anode material for high-performance lithium batteries

Abstract

It’s challenging to obtain pure-phase metastable tetragonal niobium pentoxide (M-Nb2O5) by conventional heating methods, due to the thermodynamical stable temperature region of M-Nb2O5 partially overlaps with that of H- or T-type Nb2O5. Herein, the pure-phase M- ​Nb2O5 is synthesized by utilizing the confinement of amorphous SiO2 shells, and the pure-phase M-Nb2O5 (without SiO2) is investigated as anode material of lithium-ion batteries. The shells can not only cut off the mutual integration among Nb2O5 particles, but also inhibit the rearrangement and mobility of the atoms inside via forming Si-O-Nb bond at the interface, thus could widen the thermodynamic and kinetic stability stable regions of the M-Nb2O5. The physical and electrochemical performance of pure M-Nb2O5 (without SiO2) is characterized as the anode material of lithium-ion batteries, which exhibits an initial capacity of 246 mAh g-1, unprecedented high-rate performance (≈86 mAh g-1 at 4.0 ​A ​g-1) and excellent cycling stability (≈78 mAh g-1 ​at 2.0 ​A ​g-1 after 1000 cycles).