Trifunctional Copper-Substitution in LiMn0.6Fe0.4PO4 Nanocrystal for Enhanced Lithium Storage

LiMn0.6Fe0.4PO4 is limited in practical applications due to its low electronic conductivity and slow Li+ diffusion rate. Therefore, Cu doping was applied to modify LiMn0.6Fe0.4PO4, and the mechanism of Cu2+ “three-function” synergistic enhancement of the cathode material performance was explored. Compared to the undoped sample (LMFP), the Cu-doped sample (LMFP-Cu 1%) exhibited significantly improved electronic conductivity and Li+ diffusion coefficient. First-principles calculations also confirmed the high electronic conductivity and low Li+ diffusion barrier of LiMn0.6Fe0.4PO4@C. Additionally, LiMn0.6Fe0.39Cu0.01PO4@C demonstrated excellent rate performance and cycling stability, with discharge capacities of 160.3 mA h g–1 and 121.2 mA h g–1 at 0.1 and 2C rates, respectively. After 200 cycles at 1C rate, the capacity retention was 92.5%. The first principle calculation of DFT can help to show that the introduction of Cu can effectively reduce the diffusion barrier and intrinsic conductivity of Li+, in situ XRD analysis revealed that LiMn0.6Fe0.39Cu0.01PO4@C exhibited good structural stability and reversibility. The incorporation of Cu2+ represents a promising approach to improving the lithium storage capabilities of LiMn0.6Fe0.4PO4 cathode materials.