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Role of Cu and Mg Dopants in Modifying Structural and Electronic Properties of LiFePO₄: A DFT Study Batteries using First-Principles Study
1Institute of Science , Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia
2Faculty of Applied Science, UiTM Shah Alam, Shah Alam, Selangor, Malaysia
3Institute of Science, UiTM Shah Alam, Shah Alam, Selangor, Malaysia
4Faculty of Defence Science & Technology, Universiti Pertahanan Nasional Malaysia, Kuala Lumpur, Kuala Lumpur, Malaysia
*Email Address : hamizahzaki@uitm.edu.my
Abstract : Lithium iron phosphate (LiFePO₄) has attracted considerable attention as a cathode material for lithium-ion batteries due to its excellent thermal stability, long cycle life, and environmental benignity. Despite being an efficient cathode material, it suffers from significant drawbacks in high-rate applications because of its inherently low intrinsic conductivity. In this work, the effect of Mg and Cu substitution at Fe site in LiFePO4 have been studied using the first principles approach based on Density Functional Theory (DFT), with a GGA-PBE + U approach where a Hubbard U correction is applied to better explain for strong on-site Coulomb interactions between Fe-3d electrons. The results demonstrate that substitution with Cu and Mg leads to a decrease in the lattice parameters compared to pristine LiFePO₄. This lattice contraction may influence ion diffusion pathways and structural stability. It is also improving the electronic structure and reduces the band gap to 3.754 eV for Mg-doped LiFePO₄ and 0.506 eV for Cu-doped LiFePO₄ suggesting a possible increase in electronic conductivity. LiFe₁₋ₓMₓPO₄ (M = Cu, Mg) doped structures also show improved structural stability in comparison to the undoped material. Therefore, this work can provide valuable insight into dopant effect on the performance of LiFePO4 based electrode.
Keywords : LiFePO4, Density Functional Theory, Structural Properties, Electronic Properties, Cathode