Enhanced electrochemical performance of LiMn0.6Fe0.4PO4/C via Co and Ti dual-doping with gradient structural design
Xueyin Wang, Chunyan Yu, Yujing Li, Jiahui Xu, Yanjun Zhong, Zhenguo Wu, Xinlong Wang, Benhe Zhong
Abstract
LiMn x Fe 1- x PO 4 are considered highly promising cathode materials for next-generation lithium-ion batteries due to its high operating voltage, high energy density, excellent thermal stability, and environmental friendliness. To address the intrinsic limitations of LiMn x Fe 1- x PO 4 cathode materials, including poor electronic conductivity and limited cycling stability, a Co and Ti co-doped LiMn 0.6 Fe 0.4 PO 4 material with a gradient co-doping structure (denoted as LMFP-Co@Ti) was successfully synthesized via a two-step carbothermal reduction process. The Ti-rich outer layer effectively suppresses Mn dissolution and mitigates Jahn-Teller distortions, while the Co-doped inner layer enhances electronic conductivity and Li + diffusion kinetics, achieving an optimized balance between electrochemical activity and structural integrity. Electrochemical evaluations demonstrate that the LMFP-Co@Ti electrode delivers an initial discharge capacity of 137.67 mAh g −1 at 1C and retains 80.5 % of its capacity after 500 cycles, markedly outperforming pristine LiMn 0.6 Fe 0.4 PO 4 (LMFP) and the uniformly co-doped a uniformly co-doped sample LiMn 0.6 Fe 0.36 Co 0.01 Ti 0.03 PO 4 /C (LMFP-CoTi). Even under high-rate conditions (10C), the LMFP-Co@Ti maintains an impressive discharge capacity of 100.94 mAh g −1 , confirming its superior rate capability and long-term cycling stability. This work provides new insights into the rational design of dual-doped olivine-type cathodes, demonstrating that the gradient structure can effectively balance high-rate performance and long-term structural stability for next-generation lithium-ion batteries.