Optimizing the Electrochemical Performance of Olivine LiMn<sub><i>x</i></sub>Fe<sub>1–<i>x</i></sub>PO<sub>4</sub> Cathode Materials: Ongoing Progresses and Challenges
Enhao Xu, Xiaobo Sun, Wei Lyv, Fangbing Li, Ruixing Li, Wenlong Cai, Hao Wu, Kaipeng Wu, Yun Zhang
Abstract
LiMn x Fe 1– x PO 4 is the most promising olivine-type cathode material following LiFePO 4 in terms of development potential. However, several technological challenges remain in its widespread application, particularly in terms of its low electronic conductivity, slow Li + diffusion rate, and undetermined optimal Mn/Fe ratio. To date, enormous efforts have been devoted to addressing the intrinsic defects of LiMn x Fe 1– x PO 4 to facilitate its electrochemical kinetics, and some companies have launched first-generation LiMn x Fe 1– x PO 4 . In this review, the structural characteristics, lithium storage mechanism, and synthesis methods of LiMn x Fe 1– x PO 4 are first introduced. Wherein, a particular emphasis is placed on the rational design of precursors with tunable composition and tailored architecture, encompassing the Mn–Fe binary precursors and Mn–Fe–P ternary precursors. Then, up-to-date optimization strategies for improving the electrochemical performance of LiMn x Fe 1– x PO 4, such as Mn/Fe ratio optimizing, conductive material compositing, element doping, and morphology controlling are discussed comprehensively, with a special focus on the regulation of additional discharge plateau, which not only prevents the decrease of energy density but also maintains the consistency of LiMn x Fe 1– x PO 4 batteries. Finally, the critical issues, existing challenges, new research directions, and perspectives on further commercialization of LiMn x Fe 1– x PO 4 are also discussed.