Comprehensive Understanding of Structure Transition in LiMnyFe1−yPO4 during Delithiation/Lithiation

Abstract

AbstractThe complexity of structural changes in LiMnyFe1−yPO4 (LMFP) during delithiation/lithiation poses unique challenges in kinetics and cycling, distinguishing it significantly from LiFePO4. Therefore, comprehending the delithiation/lithiation mechanism of LMFP is essential to optimize material design, synthesis, and battery application management. However, existing reports show apparent discrepancies and contradictions. This paper elucidates the relaxation property of LMFP, providing a comprehensive review of crystal structure and electronic structure change mechanisms during delithiation/lithiation based on in situ characterization. Regarding crystal structure transition, variations in LMFP's compositional uniformity across different literature, stemming from differences in the synthesis process, may contribute to multiple mechanisms. Concerning electronic structure changes, the chemical environments between Fe and Mn are mutual interaction, and the sluggish kinetics of the Mn2+/Mn3+ reaction suggest partial charge compensation by oxygen in the phosphate group. Building on these findings, the paper addresses existing research deficiencies and identifies potential directions for future investigations into the delithiation/lithiation mechanism of LMFP, aiming to provide a solid theoretical foundation for developing new olivine‐type cathode materials with superior electrochemical performance.