Trace LiBF4 Enabling Robust LiF-Rich Interphase for Durable Low-Temperature Lithium-Ion Pouch Cells,ACS Energy Letters

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Trace LiBF4 Enabling Robust LiF-Rich Interphase for Durable Low-Temperature Lithium-Ion Pouch Cells
ACS Energy Letters ( IF 19.3 ) Pub Date : 2024-09-13 , DOI: 10.1021/acsenergylett.4c01616
Nan Qin ₁ , Jing Chen ₁ , Yanyan Lu ₁ , Yifan Li ₁ , Wenlong Cai ₂ , Jiantao Li ₃ , Cunman Zhang ₁ , Zonghai Chen ₃ , Jim P. Zheng ₄ , Liming Jin ₁

Affiliation

Lithium-ion batteries (LIBs) with electrolytes containing lithium tetrafluoroborate (LiBF₄) can achieve large capacity retention under low temperature, but the accompanying rapid capacity decay inhibits commercialization. Here, the impact of LiBF₄ as a supplemental salt to LiPF₆ is systematically investigated using low ethylene carbonate (EC)-content electrolytes, along with a low-melting-point cosolvent. It is found that rational adjustment of the amount of LiBF₄ could not only regulate the interactions of anions and solvents in Li⁺ solvation sheaths but also tune the composition and morphology of solid electrolyte interphase (SEI). It is worth noting that electrolytes with trace amount of LiBF₄ (0.05 M) show synergetic interaction between PF₆^– and Li⁺ and decreased interaction between EC and Li⁺, achieving a dense and LiF-rich SEI, which enables a 200 mAh pouch cell with less gas generation, long-lived cycling, and higher low-temperature capacity, simultaneously. This work provides new insight into utilizing trace LiBF₄ for stable interface construction of durable low-temperature LIBs.

中文翻译：

微量 LiBF4 可为耐用的低温锂离子软包电池提供坚固的富 LiF 界面

使用含有四氟硼酸锂（LiBF ₄ ）的电解质的锂离子电池（LIB）可以在低温下实现较大的容量保持率，但随之而来的快速容量衰减阻碍了商业化。在此，使用低碳酸亚乙酯（EC）含量电解质以及低熔点共溶剂系统地研究了LiBF ₄作为LiPF ₆补充盐的影响。研究发现，合理调节LiBF ₄的用量不仅可以调节Li ⁺溶剂化鞘中阴离子和溶剂的相互作用，还可以调节固体电解质界面相（SEI）的组成和形貌。值得注意的是，含有微量LiBF ₄ (0.05 M)的电解质表现出PF ₆ ^-和Li ⁺之间的协同相互作用，并减少了EC和Li ⁺之间的相互作用，实现了致密且富含LiF的SEI，从而实现了200 mAh的软包电池同时具有更少的气体产生、更长的循环寿命和更高的低温容量。这项工作为利用微量LiBF ₄构建耐用低温LIB的稳定界面提供了新的见解。

更新日期：2024-09-13

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