Electrode potential influences the reversibility of lithium-metal anodes
Electrode potential influences the reversibility of lithium-metal anodes
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DOI：
10.1038/s41560-022-01144-0
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发表时间：
2022-10-27
期刊：
影响因子：
56.7
通讯作者：
Yamada, Yuki
中科院分区：
文献类型：
--
作者：
Ko, Seongjae;Obukata, Tomohiro;Yamada, Yuki
了解锂金属负极在电池中的可逆性是一项具有挑战性的任务。在这里，作者认为锂电极电位是影响负极可逆性的关键因素，并提出了一种提高循环性能的电解液设计。锂-金属电池是一种很有前途的技术，可以满足对高能量密度存储系统的新需求。然而，由于不断的电解液分解，它们的循环遇到了低的库仑效率(CE)。提高固体电解质界面(SEI)的稳定性可以抑制分解，提高CE。然而，仅靠SEI形态和化学不能解释CE，仍然缺乏完整的解释。本文报道了在不同的电解液中，锂电极电势的较大位移(-gt；0.6V)及其与Li+配位结构的关联对CE的影响。机器学习回归分析和振动光谱分析表明，离子对的形成对于锂电极电位的上移是必不可少的，也就是削弱了锂的还原能力，从而导致高的CE和减少的电解液分解。具有增强的离子配对溶液结构的各种电解液被设计为能够显著提高CE(>；99%)。
It is a challenging task to understand the reversibility of lithium-metal anodes in batteries. Here the authors identify the lithium electrode potential as a critical factor that affects the anode reversibility and subsequently propose an electrolyte design to improve the cycling performance.Lithium-metal batteries are a promising technology to address the emerging demand for high-energy-density storage systems. However, their cycling encounters a low Coulombic efficiency (CE) due to the unceasing electrolyte decomposition. Improving the stability of solid electrolyte interphase (SEI) suppresses the decomposition and increases CE. However, SEI morphology and chemistry alone cannot account for CE, and a full explanation is still lacking. Here we report that in diverse electrolytes, the large shift (>0.6 V) in the Li electrode potential and its association with the Li+ coordination structure influence the CE. Machine learning regression analysis and vibrational spectroscopy revealed that the formation of ion pairs is essential for upshifting the Li electrode potential, that is, for weakening the reducing ability of Li, which would lead to a high CE with diminished electrolyte decomposition. Various electrolytes with enhanced ion-pairing solution structure are designed to enable a significantly improved CE (>99%).