Enhanced electrochemical properties of F-doped Li2MnSiO4/C for lithium ion batteries

The Li 2 MnSiO 4 as a novel cathode material for lithium ion batteries, performs high specific capacity, high thermal stability, low cost and etc. However, it suffers from relatively low electronic conductivity and lithium ion diffusion rate. Herein, we successfully introduce fluorine to Li 2 MnSiO 4 (Li 2 MnSiO 4-x F x , x = 0.00, 0.01, 0.03 and 0.05) to overcome these obstacles. The results show that F doping not only enlarges the lattice parameters but also decreases the particle size, synergistically improving the lithium ion diffusion of Li 2 MnSiO 4 . Moreover, F doping increase electronic conductivity of Li 2 MnSiO 4 /C by inhibiting the formation of C-O bonds in the carbon layers . Meanwhile, F doping improves the crystallinity and stabilizes the crystal structure of Li 2 MnSiO 4 . Finally, the Li 2 MnSiO 3.97 F 0.03 /C with the best electrochemical performances delivers the initial specific discharge capacity of 279 mA h g −1 at 25mA g −1 current density from 1.5 V to 4.8 V. Also, it maintains a higher capacity (201 mA h g −1 ) than F-free Li 2 MnSiO 4 (145 mA h g −1 ) after 50 cycles.