Structural evolution of dendritic-structured Mg0.01V2O5 film electrodes of lithium-ion batteries during cycling

The development of viable high-capacity cathode materials is still a challenge for lithium-ion batteries (LIBs). In this work, Mg0.01V2O5 films with an interesting dendritic structure were grown in-situ on indium-tin oxide (ITO) conductive glass by a low temperature liquid phase deposition. The results exhibited the morphologies and properties of film electrodes were greatly affected by different annealing temperature. Among them, the Mg0.01V2O5 film electrode annealed at 450 degrees C showed the best electrochemical performance. It provided a highcapacity of 164.7 mA h m- 2, and 141.2 mA h m- 2 after 100 cycles that capacity retention of 85.7% at 176 mA m- 2 in the LIB system. In addition, good cycling stability and rate performance were also impressive. The mechanism of Li+ insertion and extraction in the film electrode Mg0.01V2O5 was investigated by analyzing the phase evolution, lattice deformation, and elementary composition and valence of the film electrode after enduring electrochemical cycles. The insertion of Li+ in the interlayer allowed the creation of a new phase and the different diffusion rate of Li+ in the (010) crystal plane of the main phase, which caused the splitting behavior of the X-ray diffraction peaks of this crystal plane. Encouragingly, it was the new phase produced during the cycle that worked with the principal phase, improving the diffusion kinetics and enhancing the electrochemical properties of LIBs. This work may provide a promising strategy to improve performance for LIBs.