A structural and electrochemical study of lithium-ion battery electrolytes using an ethylene sulfite solvent: from dilute to concentrated solutions
A structural and electrochemical study of lithium-ion battery electrolytes using an ethylene sulfite solvent: from dilute to concentrated solutions
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使用亚硫酸乙烯酯溶剂的锂离子电池电解质的结构和电化学研究：从稀溶液到浓溶液
DOI：
10.1039/d2cp03616a
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发表时间：
2022
影响因子：
3.3
通讯作者：
Fujii Kenta
中科院分区：
文献类型：
--
作者：
Suzuki Kenzo;Sawayama Saki;Deguchi Yuna;Sai Ryansu;Han Jihae;Fujii Kenta
我们报告了使用亚硫酸乙二酯（ES）溶剂作为锂离子电池（LIB）电解质添加剂的锂（Li）离子电池（LIB）电解质溶液的结构和电化学特性。从稀释到高浓度的ES溶液与锂双（氟磺酰基）氨基（LiFSA），锂离子络合物的形成进行了研究，使用组合的拉曼和红外光谱的研究与密度泛函理论（DFT）计算的援助，以定量地确定其溶剂化和离子对结构取决于锂盐浓度（cLi）。结果表明，在稀溶液（<1.0 mol dm−3）中，Li离子与ES分子完全溶剂化形成四面体状[Li（ES）4]+络合物;然而，随着cLi的增加（高达2.5 mol dm−3），Li离子络合物的结构发生变化，形成与ES和FSA阴离子配位的接触离子对。它还表明，进一步增加cLi至约3.0 mol dm-3导致离子聚集体的形成，即，通过几个FSA阴离子连接的多个Li离子络合物。LiFSA/ES电解质溶液表现出可逆的锂离子插入/脱嵌反应到/从石墨阳极，而不管cLi。这是由于电极上的高级ES衍生的钝化膜，这是由于被捕获在Li离子配位球内的ES分子的优先还原分解的结果。充放电测试表明，浓缩LiFSA/ES溶液具有高C倍率性能，上级使用传统有机溶剂的浓缩电解质溶液。
We report the structural and electrochemical characteristics of lithium (Li)-ion battery (LIB) electrolyte solutions using an ethylene sulfite (ES) solvent that is used as an electrolyte additive for LIBs. From dilute to highly concentrated ES solutions with lithium bis(fluorosulfonyl)amide (LiFSA), the formation of Li-ion complexes was investigated using a combined Raman and infrared spectroscopy study with the aid of density functional theory (DFT) calculations to quantitatively determine their solvation and ion-pair structures depending on the Li salt concentration (cLi). The results reveal that, in the dilute solutions (<1.0 mol dm−3), Li-ions are fully solvated with ES molecules to form a tetrahedral-like [Li(ES)4]+ complex; however, with the increasing cLi (up to 2.5 mol dm−3), the Li-ion complex changes in structure to form contact ion-pairs coordinated with both ES and FSA anions. It also reveals that further increasing cLi to approximately 3.0 mol dm−3 leads to the ionic aggregate formation, i.e., multiple Li-ion complexes linked via several FSA anions. LiFSA/ES electrolyte solutions exhibited a reversible Li-ion insertion/deinsertion reaction into/from the graphite anode irrespective of cLi. This is due to the high-grade ES-derived passivation films on the electrode as a result of the preferential reductive decomposition of the ES molecules trapped within the Li-ion coordination sphere. According to the charge–discharge test, the concentrated LiFSA/ES solutions exhibited the high C-rate performance, which is superior to the concentrated electrolyte solutions using conventional organic solvents.