Surface-assembled highly flexible Na3(VOPO4)2F nanocube cathode for high-rate binder-free Na-ion batteries

Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances. Herein, a new type of flexible Na-3(VOPO4)(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothermal method for the first time. The cathode is able to exhibit superior rate capability and stable cycling performance up to 1000 cycles, due to the surface-assembling of crystalline nanocubes on carbon fibers. In addition, it shows good mechanical flexibility, nearly no capacity decay is observed after continuous bending of 500 times. With this novel cathode and a directly-grown Na2Ti2O5 anode, a fully binder-free Na-ion battery is assembled. It can deliver a high working voltage and increased gravimetric energy/power densities (maximum values: 220.2 Wh/kg; 5674.7 W/kg), and can power a LED indicator at bending angles from 0 degrees to 180 degrees. (C) 2020 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.