Heteroatoms-doped carbon effect on LiFePO4 cathode for Li-ion batteries

Surface modification with heteroatoms-doped carbon is applied to improve the electrochemical properties of LiFePO4 (LFP) as a cathode for lithium-ion batteries (LIBs). The preparation of nitrogen and sulfur dual-doped (N, S-doped) carbon-coated LFP (NSC@LFP) with a uniform carbon coating layer involves a solid-state method together with thermal treatment. Methionine is utilized as a source of N, S-doped carbon. Applying physical and electrochemical characterizations, the effects of surface modification with heteroatom-doped carbon have been examined. The results demonstrate that the surface-coated samples exhibit improved electrochemical activity as a cathode for LIBs, with a specific capacity of 155 mAh g−1 at 0.1 C, 126 mAh g−1 at 1 C, and a capacity retention of 99% after 200 cycles. Additionally, the rate capability shows an increasing difference as the current density increases, indicating that the N, S-doped carbon coating layer enhances the ionic/electronic conductivity and shortens the ion diffusion channels, which leads to the better electrochemical kinetics of NSC@LFP.