Facile preparation of hydrated vanadium pentoxide nanobelts based bulky paper as flexible binder-free cathodes for high-performance lithium ion batteries

Hydrated vanadium pentoxide (V ₂O ₅·0.44H ₂O, HVO) nanobelts were synthesized by a simply high-yield (e.g. up to ∼99%) hydrothermal approach. The length of these nanobelts was up to several hundred micrometers while the diameter was only ∼20 nm and the thickness was ∼10 nm. Binder-free bulky papers were prepared by using these HVO nanobelts and were tested as Li ion battery cathodes. The unique architecture of the HVO bulky paper provides hierarchical porous channels and large specific surface area, which facilitate fast ion diffusion and effectively strain relaxation upon charge-discharge cycling. The electrochemical tests revealed that the flexible HVO cathode could deliver high reversible specific capacities with ∼100% Coulombic efficiency, especially at high C rates. For example, it achieved a reversible capacity of 163 mAh g ^-1 at 6.8 C.