Uncovering the Solvation Structure of LiPF6-Based Localized Saturated Electrolytes and Their Effect on LiNiO2-Based Lithium-Metal Batteries,Advanced Energy Materials

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Uncovering the Solvation Structure of LiPF6-Based Localized Saturated Electrolytes and Their Effect on LiNiO2-Based Lithium-Metal Batteries
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2022-08-02 , DOI: 10.1002/aenm.202201911
Laisuo Su ₁ , Xunhua Zhao ₁ , Michael Yi ₁ , Harry Charalambous ₂ , Hugo Celio ₁ , Yuanyue Liu ₁ , Arumugam Manthiram ₁

Affiliation

Electrolytes play a critical role in stabilizing highly reactive lithium-metal anodes (LMAs) and high-voltage cathodes for rechargeable lithium-metal batteries (LMBs). Localized high concentration electrolytes (LHCEs) have achieved remarkable success in the context of LMBs. However, the state-of-the-art LHCEs are based on LiFSI salt, which is prohibitively expensive. Here, the utility of low-cost LiPF₆ salt in localized saturated electrolytes (LSEs) with a series of solvents and diluents in LMBs with cobalt-free LiNiO₂ cathode is systematically explored. Experimental and theoretical analyses reveal that the unique solvation structure formed not only changes the distribution of solvents and anions but also alters the atom–atom distances within them, leading to different reduction and oxidation stabilities compared to low-concentration electrolytes. In addition, LSEs help form LiF-rich interphase layers on the LMA and LiNiO₂ cathode, protecting the electrodes from degradation during cycling. Different LSEs also lead to differences in lithium plating morphology and impedance buildup during cycling, impacting the performance of LMBs. The solvent and diluent must be carefully selected for compatibility with a lithium salt when developing LHCEs and LSEs for LMBs.

中文翻译：

揭示基于 LiPF6 的局部饱和电解质的溶剂化结构及其对 LiNiO2 基锂金属电池的影响

电解质在稳定可充电锂金属电池 (LMB) 的高反应性锂金属阳极 (LMA) 和高压阴极方面发挥着关键作用。局部高浓度电解质 (LHCE) 在 LMB 的背景下取得了显着的成功。然而，最先进的 LHCE 是基于 LiFSI 盐的，这种盐非常昂贵。在这里，低成本 LiPF ₆盐在具有一系列溶剂和稀释剂的局部饱和电解质 (LSE) 中在具有无钴 LiNiO _{2的 LMB 中的应用}阴极进行了系统的探索。实验和理论分析表明，形成的独特溶剂化结构不仅改变了溶剂和阴离子的分布，还改变了它们之间的原子-原子距离，导致与低浓度电解质相比具有不同的还原和氧化稳定性。此外，LSE 有助于在 LMA 和 LiNiO ₂正极上形成富含 LiF 的界面层，从而保护电极在循环过程中不会退化。不同的 LSE 还会导致循环过程中锂电镀形态和阻抗累积的差异，从而影响 LMB 的性能。在为 LMB 开发 LHCE 和 LSE 时，必须仔细选择溶剂和稀释剂，以便与锂盐兼容。

更新日期：2022-08-02

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