Close-packed chalcogenide spinels, such as MgSc₂Se₄, MgIn₂S₄, and MgSc₂S₄, show potential as solid electrolytes in Mg batteries, but are affected by non-negligible electronic conductivity, which contributes to self-discharge when used in an electrochemical storage device. Using first-principles calculations, we evaluate the energy of point defects as a function of synthesis conditions and Fermi level to identify the origins of the undesired electronic conductivity. Our results suggest that Mg-vacancies and Mg-metal antisites (where Mg is exchanged with Sc or In) are the dominant point defects that can occur in the systems under consideration. While we find anion-excess conditions and slow cooling to likely create conditions for low electronic conductivity, the spinels are likely to exhibit significant n-type conductivity under anion-poor environments, which are often present during high-temperature synthesis. Finally, we explore extrinsic aliovalent doping to potentially mitigate the electronic conductivity in these chalcogenide spinels. The computational strategy is general and can be easily extended to other solid electrolytes (and electrodes) to aid the optimization of the electronic properties of the corresponding frameworks.

中文翻译：

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点缺陷在尖晶石镁硫属化物导体中的作用

密排硫族元素尖晶石，例如MgSc ₂ Se ₄，MgIn ₂ S ₄和MgSc ₂ S ₄，显示出作为镁电池中固体电解质的潜力，但受到不可忽略的电子导电性的影响，当用于电化学存储设备时，电子导电性会导致自放电。使用第一性原理计算，我们根据合成条件和费米能级来评估点缺陷的能量，以识别不良电子电导率的来源。我们的结果表明，镁空位和镁金属反位点（其中镁与Sc或In交换）是在考虑中的系统中可能发生的主要缺陷。虽然我们发现阴离子过多的条件和缓慢的冷却可能会为低电子电导率创造条件，但尖晶石很可能在贫阴离子的环境中表现出显着的n型电导率，而在高温合成过程中通常会出现这种情况。最后，我们探索外源性异价金属掺杂，以潜在地减轻这些硫族化物尖晶石中的电子电导率。计算策略是通用的，可以轻松扩展到其他固体电解质（和电极），以帮助优化相应框架的电子性能。