Fe and Ti co-doped LiCoPO4 as High-voltage Cathode Materials for Lithium-ion Batteries, Journal of Colloid and Interface Science,706, 139617(2026)
Shu-Yu Chen, Shao-Chu Huang, Tsung-Yi Chen, Wen-Hsuan Lu, Yen-Lin Chen, Cho-Jen Tsai*, Han-Yi Chen*
2026/05/21
Lithium cobalt phosphate (LiCoPO4) is a high-voltage cathode material, offering a high theoretical capacity of ∼167 mA h g−1 and a cobalt redox potential up to ∼4.8 V, which enable high energy density. However, LiCoPO4 suffers from low ionic conductivity owing to the structural limitation of one-dimensional [0 1 0] lithium diffusion pathway. In this study, both Fe and Ti are introduced to substitute the lattice site of Co, to investigate the synergistic effects of Ti co-doping in 10 at.% Fe-substituted LiCoPO4. While Fe substitution has been widely reported to enhance electrochemical stability, Ti, with a higher valence than Co, is expected to generate cation vacancies that facilitate lithiation and delithiation. The electrochemical, kinetic, and structural properties of LiCo0.9-2xFe0.1TixPO4 were systematically evaluated. The Fe and Ti co-doped sample exhibited an initial discharge capacity of 121 mA h g−1 at 0.1C and a capacity retention of 85 % after 200 cycles at 1C. Moreover, lithium-ion diffusion coefficients derived from PITT and GITT methods were in the range of 10−11–10−10 cm2 S−1, with higher values observed for Fe and Ti co-doping compared to Fe-only doping, contributing to improved rate performance. In addition, operando XRD indicated that Ti co-doping transformed the two-phase transition into a solid-solution behavior, demonstrating faster reaction kinetics. Overall co-doping with Fe and Ti enhanced both the structural and electrochemical properties LiCoPO4 as a high-voltage cathode in lithium-ion battery.
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