Shi Chenyang, Wang Mengran, Tehrani Zari, Hong Bo, Wang Mengnan, Tan Rui, Margadonna Serena, Lai Yanqing, Titirici Maria Magdalena
School of Metallurgy and Environment, Central South University, Changsha, Hunan, 410083, China.
Engineering Research Centre of Advanced Battery Materials, The Ministry of Education, Changsha, Hunan, 410083, China.
Adv Sci (Weinh). 2025 Feb;12(6):e2411826. doi: 10.1002/advs.202411826. Epub 2024 Dec 16.
Flame-retardant phosphate-based electrolytes effectively enhance lithium-ion battery safety but suffer from poor compatibility with graphite anodes and high-voltage cathodes, hindering scalability. Fluorinated phosphates, though widely used, increase interfacial resistance at the anode, degrading performance. In this work, carbonate solvents with strong polarity are introduced to prevent tris(2,2,2-trifluoroethyl) phosphate (TFEP) from participating in the solvation structure of lithium ions. This strategy forms a quasi-localized high-concentration solvation structure, thereby restricting the reduction of TFEP and its impact on the graphite anode. The LiNiMnCoO (NCM811) | Graphite (Gr) pouch cell with optimized electrolyte exhibits a capacity retention rate of 80.1% after 370 cycles at 0.5C, which is much more stable than the electrolyte with TFEP-involved solvation structure (capacity retention rate: 47.1% after 300 cycles). The corresponding pouch cell with cut-off voltage to 4.5 V exhibits a capacity retention rate of 82.8% after 125 cycles, significantly outperforming cells employing commercial carbonate electrolytes (capacity retention rate: 56.9% after 125 cycles). Thus, the developed quasi-localized high-concentration solvation structure can effectively stabilize the electrode interface, greatly enhancing the cycling performance of phosphate-based flame-retardant electrolytes.
阻燃型磷酸盐基电解质有效地提高了锂离子电池的安全性，但与石墨负极和高压正极的兼容性较差，阻碍了其规模化应用。氟化磷酸盐虽然被广泛使用，但会增加负极的界面电阻，导致性能下降。在这项工作中，引入了强极性的碳酸酯溶剂，以防止三（2,2,2-三氟乙基）磷酸酯（TFEP）参与锂离子的溶剂化结构。该策略形成了一种准局部高浓度溶剂化结构，从而限制了TFEP的还原及其对石墨负极的影响。采用优化电解质的LiNiMnCoO（NCM811）|石墨（Gr）软包电池在0.5C下循环370次后，容量保持率为80.1%，比具有TFEP参与的溶剂化结构的电解质（300次循环后容量保持率：47.1%）稳定得多。相应的截止电压为4.5V的软包电池在125次循环后容量保持率为82.8%，明显优于采用商业碳酸酯电解质的电池（125次循环后容量保持率：56.9%）。因此，所开发的准局部高浓度溶剂化结构可以有效地稳定电极界面，大大提高基于磷酸盐的阻燃电解质的循环性能。
