The kinetic processes during delithiation/lithiation of Li_xMn_0.8Fe_0.2PO₄ are thoroughly investigated through operando x-ray diffraction and in situ electrochemical impedance spectroscopy combined with galvanostatic intermittent titration technique (GITT), by which new insights on the phase propagation and sluggish kinetics of LiMn_0.8Fe_0.2PO₄ (LMFP) cathode materials are elaborated. In situ analyses on the solvothermally synthesized carbon-coated LMFP mesocrystals reveal that the phase-propagation mechanisms differ during delithiation/lithiation processes, and the sluggish kinetics of LMFP followed by the limitation of achievable (dis)charge capacities originate from the poor apparent Li⁺ diffusivity, which is triggered by Mn redox reaction. Based on the in-depth characterization of the reaction kinetics in LMFP mesocrystals, our work provides fundamental understanding to design high-performance Mn-based olivine cathodes.

通过操作X射线衍射和原位电化学阻抗谱结合恒电流间歇滴定技术（GITT），对Li _x Mn _0.8 Fe _0.2 PO ₄脱锂/锂化过程中的动力学过程进行了深入研究，从而获得了有关相传播和相变的新见解。详细阐述了LiMn _0.8 Fe _0.2 PO ₄（LMFP）正极材料的缓慢动力学。原位对溶剂热合成碳包覆的LMFP介晶的分析表明，在去锂化/锂化过程中，相传播机理不同，并且LMFP的动力学缓慢，随后可达到的（放电）容量受限，是由于不良的表观Li ⁺扩散性引起的，这是由锰的氧化还原反应触发的。基于LMFP介晶中反应动力学的深入表征，我们的工作为设计高性能Mn基橄榄石阴极提供了基础知识。