高浓度LiPF6/砜电解质：结构、传输性能和电池应用,Physical Chemistry Chemical Physics

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高浓度LiPF6/砜电解质：结构、传输性能和电池应用
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-10-19 , DOI: 10.1039/d3cp04561g
Yosuke Ugata _{1,

2} , Yichuan Chen ₁ , Shuhei Miyazaki ₁ , Shohei Sasagawa ₁ , Kazuhide Ueno _{1,

2} , Masayoshi Watanabe ₂ , Kaoru Dokko _{1,

2}

Affiliation

不易燃且氧化稳定的砜是用于热稳定高压锂电池的有前途的电解质溶剂。此外，环丁砜基高浓度电解质（HCE）表现出高Li ⁺离子迁移数。然而，尚未研究LiPF _{6作为锂电池用砜基HCE 中的主要盐。}_{在本研究中，我们研究了 LiPF 6}和以下砜溶剂的二元和三元混合物的相行为、溶剂化物结构和输运特性：环丁砜 (SL)、二甲基砜 (DMS)、乙基甲基砜 (EMS) 和 3 -甲基环丁砜（MSL）。_{LiPF 6 /SL和LiPF 6}_/ DMS混合物中分别形成了具有高熔点的稳定结晶溶剂化物Li(SL) ₄ PF ₆和Li( DMS) _2.5 PF ₆。相比之下，LiPF ₆ /EMS、LiPF ₆ /MSL和LiPF ₆ /SL/另一种砜混合物在很宽的温度范围内保持液态。拉曼光谱显示SL和另一种砜与Li ⁺离子竞争性配位以解离三元混合物中的LiPF _{6 。}尽管由于粘度增加，离子电导率随着 LiPF ₆浓度的增加而降低，但通过交换 HCE 中的配体，Li ^{+离子比 PF}₆^-扩散得更快[LiPF ₆ ]/[SL]/[DMS] = 1/2/2 ，导致比传统锂电池电解质更高的锂离子迁移数。

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High-concentration LiPF6/sulfone electrolytes: structure, transport properties, and battery application

Non-flammable and oxidatively stable sulfones are promising electrolyte solvents for thermally stable high-voltage Li batteries. In addition, sulfolane-based high-concentration electrolytes (HCEs) show high Li⁺ ion transference numbers. However, LiPF₆ has not yet been investigated as the main salt in sulfone-based HCEs for Li batteries. In this study, we investigated the phase behaviors, solvate structures, and transport properties of binary and ternary mixtures of LiPF₆ and the following sulfone solvents: sulfolane (SL), dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), and 3-methyl sulfolane (MSL). The stable crystalline solvates Li(SL)₄PF₆ and Li(DMS)_2.5PF₆ with high melting points were formed in the LiPF₆/SL and LiPF₆/DMS mixtures, respectively. In contrast, LiPF₆/EMS, LiPF₆/MSL, and LiPF₆/SL/another sulfone mixtures remained liquids over a wide temperature range. Raman spectroscopy revealed that SL and another sulfone are competitively coordinated to Li⁺ ions to dissociate LiPF₆ in the ternary mixtures. Although the ionic conductivity decreased with increasing LiPF₆ concentration due to an increase in viscosity, Li⁺ ions diffused faster than PF₆⁻ via exchanging ligands in the HCE [LiPF₆]/[SL]/[DMS] = 1/2/2, resulting in a higher Li ion transference number than that in conventional Li battery electrolytes.

更新日期：2023-10-19

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