Superior electronic/ionic kinetics of LiMn0.8Fe0.2PO4@C nanoparticles cathode by doping strategy toward enhanced Li-ion storage

The practical applications of LiMn0.8Fe0.2PO4 have been greatly limited due to its low electrical conductivity and inferior electrochemical reaction kinetics. Herein, a Ni-doped strategy has been employed to optimize the morphology of LiMn0.8Fe0.2PO4 nanoparticles with preferred growth orientation, leads to improved electrical/ ionic conductivity and electrode kinetic. Compared with pristine sample (Ni-D0), the electrical conductivity, ion diffusion coefficient and exchange current density of 5 mol% Ni-doped sample (Ni-D5) are obviously increased to 9.57 x 10-2 S cm-1, 3.301 x 10-11 cm2 s- 1, and 0.339 mA cm-2, respectively. The first principle calculations also confirmed the enhanced electrical conductivity of LiMn0.8Fe0.15Ni0.05PO4@C. Meanwhile, Ni-D5 exhibits good rate capability and cycling stability. Furthermore, the operando XRD analysis demonstrated its highly structural stability and reversible properties. Therefore, the Ni-doped strategy is considered a promising and effective modification approach to enhance the Li-storage capability of LiMn0.8Fe0.2PO4 cathode for high performance rechargeable second batteries.