The Jahn–Teller (JT) deformation triggers severe structural distortion and large capacity fading in the cathode materials of alkali-ion batteries. Although conventional doping containing over 20 dopant species has been demonstrated to suppress the JT effect, how the short-range and cooperative JT effect are regulated remains an open question. Recently, the new compositionally complex (high entropy) doping has been validated in various oxide cathodes and achieved “zero strain”, but the reported “synergistic effect” is largely factual reporting with a limited fundamental understanding of the link between multicomponents and the JT effect. By comparing a group of spinel LiMn₂O₄ (LMO) cathodes with tridoping sites containing one, three, or five dopants’ species, the present work shows that MnO₆ octahedral distortion systematically decreases, whereas capacity retention and structure stability systematically increase as the number of dopants’ species increases. We propose the generality rules that Mn-site doping breaks the linear continuous short-range JT distortion while 16c-sites doping disturbs the d_z²-orbital collinear ordering and mitigates the cooperative JT effect. Moreover, our complex doping strategy further buffers and rotates the JT strain, resulting in isotropic moderate volume distortion. Based on this synergic effect, both the short-range and cooperative JT effect are significantly suppressed in our synthesized multisites multicomponent doped LMO.

中文翻译：

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通过多位点组成复杂掺杂减轻 Jahn-Teller 效应的通用性规则和协同效应


Jahn-Teller （JT） 变形在碱性离子电池的正极材料中引发了严重的结构变形和大容量衰落。尽管含有 20 多种掺杂剂的常规掺杂已被证明可以抑制 JT 效应，但如何调节短程和协同 JT 效应仍然是一个悬而未决的问题。最近，新的成分复杂（高熵）掺杂已在各种氧化物阴极中得到验证并实现了“零应变”，但报道的“协同效应”主要是事实报道，对多组分与 JT 效应之间的联系的基本理解有限。通过比较一组尖晶石 LiMn₂O₄ （LMO） 阴极与包含一种、三种或五种掺杂剂种类的三掺杂位点，本研究表明，随着掺杂剂种类数量的增加，MnO₆ 八面体畸变系统性地降低，而容量保持和结构稳定性系统性地增加。我们提出了 Mn-site 掺杂打破线性连续短程 JT 畸变的一般性规则，而 16c 位点掺杂扰乱了 d_z² 轨道共线排序并减轻了协同 JT 效应。此外，我们的复杂掺杂策略进一步缓冲和旋转 JT 应变，导致各向同性的中等体积失真。基于这种协同效应，在我们合成的多位点多组分掺杂 LMO 中，短程和协同 JT 效应都被显着抑制。