Optimizing the Electrochemical Performance of Olivine LiMn_xFe_1-xPO₄ Cathode Materials: Ongoing Progresses and Challenges

LiMn_xFe_1-xPO₄ is the most promising olivine-type cathode material following LiFePO₄ 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_xFe_1-xPO₄ to facilitate its electrochemical kinetics, and some companies have launched first-generation LiMn_xFe_1-xPO₄. In this review, the structural characteristics, lithium storage mechanism, and synthesis methods of LiMn_xFe_1-xPO₄ 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_xFe_1-xPO₄, 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_xFe_1-xPO₄ batteries. Finally, the critical issues, existing challenges, new research directions, and perspectives on further commercialization of LiMn_xFe_1-xPO₄ are also discussed.