Effect of organic cations in locally concentrated ionic liquid electrolytes on the electrochemical performance of lithium metal batteries
Effect of organic cations in locally concentrated ionic liquid electrolytes on the electrochemical performance of lithium metal batteries
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DOI：
10.1016/j.ensm.2021.10.034
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发表时间：
2021-10
影响因子：
20.4
通讯作者：
Xu Liu;A. Mariani;M. Zarrabeitia;Maria E.Di Pietr;Xu Dong;G. Elia;A. Mele;S. Passerini
中科院分区：
文献类型：
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作者：
Xu Liu;A. Mariani;M. Zarrabeitia;Maria E.Di Pietr;Xu Dong;G. Elia;A. Mele;S. Passerini
有机阳离子是局部浓缩离子液体电解质的重要组成部分，但很少受到关注。在本文中，我们通过使用1-丁基-1-甲基吡咯烷鎓阳离子（Pyr 14+）或1-乙基-3-甲基咪唑鎓阳离子（Pyr 14+）的两种LCILE的比较研究，证明了它们对锂金属电池电化学性能的显著影响。结果表明，LCILEs中的有机阳离子的结构对Li+-双（氟磺酰基）酰亚胺阴离子（FSI−）配位只有有限的影响。然而，FSI−与有机阳离子的配位是不同的。与Pyr 14+相比，FSI−与Lim+的配位更少，导致Lim+基电解质（Lim BE）中的粘度比Pyr 14+基电解质（PyrBE）低，Li+传输更快。此外，在锂金属上形成的固体电解质界面（SEI）的化学组成受有机阳离子的影响。更稳定的SEI生长的存在下的Al 2 O3+导致更高的锂电镀/剥离库仑效率（99.2%）。结果，Li/LiNbBE/LiNi0.8Mn0.1Co0.1O2电池在1C放电（2 mA cm-2）时表现出185 mAh g-1的容量，并且在200次循环后的容量保持率为96%。在相同条件下，PyrBE基电池仅显示34 mAh g− 1容量，保留率为39.6%。
Organic cations are essential components of locally concentrated ionic liquid electrolytes (LCILEs), but receive little attention. Herein, we demonstrate their significant influence on the electrochemical performance of lithium metal batteries via a comparison study of two LCILEs employing either 1‑butyl‑1-methylpyrrolidinium cation (Pyr14+) or 1-ethyl-3-methylimidazolium cation (Emim+). It is demonstrated that the structure of the organic cation in LCILEs has only a limited effect on the Li+- bis(fluorosulfonyl)imide anion (FSI−) coordination. Nonetheless, the coordination of FSI−with the organic cations is different. The less coordination of FSI−to Emim+than to Pyr14+results in the lower viscosity and faster Li+transport in the Emim+-based electrolyte (EmiBE) than the Pyr14+-based electrolyte (PyrBE). Additionally, the chemical composition of the solid-electrolyte interphase (SEI) formed on lithium metal is affected by the organic cations. A more stable SEI growing in the presence of Emim+leads to a higher lithium plating/stripping Coulombic efficiency (99.2%). As a result, Li/EmiBE/LiNi0.8Mn0.1Co0.1O2cells exhibit a capacity of 185 mAh g−1at 1C discharge (2 mA cm−2) and capacity retention of 96% after 200 cycles. Under the same conditions, PyrBE-based cells show only 34 mAh g−1capacity with 39.6% retention.