Abstract Since transition metal phospho olivines gain increasing interest as cathode materials for lithium ion batteries in the last decades lots of publications appeared. Various synthesis methods were in the focus of interest as well as structural investigations of the pure LiMPO4 and mixed Li (MM′)PO4 phases (M, M′ = Fe, Mn, Co, Ni, Mg, Zn, Al) and their structural changes during electrochemical conversion. Lithium insertion and exsertion mechanisms have been studied with the help of e.g. structural, optical and electronic, and electrochemical characterisation methods. Likewise many efforts have been done for material optimisation concerning synthesis procedure or substitution. We tend to give an overview about Li (MM′Mn)PO4 (M, M′ = Mg, Fe, Co) on the basis of our results. For the greater topic of enhancement of performance and energy density of LiMnPO4 we discuss different solution approaches concerning the raise of specific capacity, redox potential and optimisation of material characteristics. Thus we consider effects due to the intrinsic conductivity, structural stability of the charged phase as well as its chemical stability against the electrolyte and the dynamic stability of the interface between charged phase and discharged phase during electrochemical conversion. For this purpose in our experimental part we focus on three different approaches: substitution with an electrochemically active transition metal, substitution with an electrochemically inactive metal in case for the manipulation of unit cell volume alternation and the substitution with electrochemically inactive metals for the purpose of providing a “lithium reservoir”. This generated “lithium reservoir” is expected to be accessible for the utilisation of a new redox step. Phase transition in mixed transition metal phospho olivines Li(MnCo)PO4 has been investigated as example for the effect of substitution with an electrochemically active transition metal. Substitution with an electrochemically inactive metal leading to binary Li(MgMn)PO4 has been structurally and electrochemically investigated. Promising new electrochemical characteristics of binary Li(MgMn)PO4 phospho olivines are introduced for the first time. When charged to high potentials (>4.9 V) the activation of the Mn3+/Mn4+ step is reported.

中文翻译：

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取代的过渡金属磷橄榄石 LiMM'PO4 (M = Mn, M' = Fe, Co, Mg)：LiMnPO4 的优化路线

摘要 由于过渡金属磷橄榄石作为锂离子电池正极材料在过去几十年中受到越来越多的关注，出现了大量出版物。各种合成方法以及纯 LiMPO4 和混合 Li (MM')PO4 相（M、M' = Fe、Mn、Co、Ni、Mg、Zn、Al）的结构研究以及它们的结构研究都受到关注。电化学转化过程中的变化。已经在例如结构、光学和电子以及电化学表征方法的帮助下研究了锂的插入和脱出机制。同样，在合成过程或替代方面的材料优化方面也做了许多努力。我们倾向于根据我们的结果给出关于 Li (MM'Mn)PO4 (M, M' = Mg, Fe, Co) 的概述。对于提高 LiMnPO4 性能和能量密度的更大主题，我们讨论了有关提高比容量、氧化还原电位和优化材料特性的不同解决方案。因此，我们考虑了由于带电相的固有电导率、结构稳定性及其对电解质的化学稳定性以及电化学转换过程中带电相和放电相之间界面的动态稳定性的影响。为此，在我们的实验部分中，我们专注于三种不同的方法：用电化学活性过渡金属替代，用电化学惰性金属替代以控制晶胞体积变化，并用电化学惰性金属替代以提供“锂储库”。预计这种生成的“锂储层”可用于利用新的氧化还原步骤。混合过渡金属磷橄榄石中的相变 Li(MnCo)PO4 已作为电化学活性过渡金属取代效果的例子进行了研究。已经在结构和电化学上研究了用电化学惰性金属取代导致二元 Li(MgMn)PO4。首次介绍了二元 Li(MgMn)PO4 磷橄榄石有希望的新电化学特性。当充电到高电位 (>4.