Wang Yuankun, Zheng Chunyu, Xie Weiwei, Liu Xiaomeng, Lu Yong, Hou Yunpeng, Ma Tao, Yan Zhenhua, Chen Jun
Frontiers Science Center for New Organic Matter, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), State Key Laboratory of Advanced Chemical Power Sources, College of Chemistry, Nankai University, Tianjin, 300071, China.
Adv Mater. 2024 Dec;36(50):e2312302. doi: 10.1002/adma.202312302. Epub 2024 Nov 6.
Phosphate-based localized high-concentration electrolytes (LHCE) feature high flame retardant and satisfactory cathodic stability for lithium metal batteries. However, stable cycling of those electrolytes at ultra-high upper cut-off voltages for long-term stability remains challenging. Herein, an ether-modified phosphate, diethyl (2-methoxy ethoxy) methylphosphonate (DMEP), is designed for high-voltage applications. The ether modification enhances the stability of the Li-DMEP-FSI coordination structure, promoting the formation of cation-anion aggregates (AGG) dominated solvation structure, which favors the generation of LiF-rich cathode electrolyte interphase layers compared to triethyl phosphate (TEP)-based LHCE. Consequently, cathode degradation, including transition-metal dissolution and electrode cracking, is well-suppressed. The LiNiCoMnO (NCM811)||Li full cells using DMEP-based LHCEs show more than 90.7% capacity retention at an ultrahigh upper cut-off voltage of 4.7 V after 100 cycles. Notably, DMEP-LHCE exhibits enhanced safety than that of TEP-LHCE, suggesting its versatility and potential for next-generation lithium metal batteries.
基于磷酸盐的局部高浓度电解质（LHCE）具有高阻燃性，并且对锂金属电池具有令人满意的阴极稳定性。然而，要使这些电解质在超高截止电压下实现稳定循环以确保长期稳定性仍然具有挑战性。在此，设计了一种醚改性的磷酸盐，即二乙基（2-甲氧基乙氧基）甲基膦酸酯（DMEP），用于高压应用。醚改性增强了Li-DMEP-FSI配位结构的稳定性，促进了以阳离子-阴离子聚集体（AGG）为主的溶剂化结构的形成，与基于磷酸三乙酯（TEP）的LHCE相比，这有利于生成富含LiF的阴极电解质界面层。因此，包括过渡金属溶解和电极开裂在内的阴极降解得到了很好的抑制。使用基于DMEP的LHCE的LiNiCoMnO（NCM811）||Li全电池在4.7 V的超高截止电压下经过100次循环后容量保持率超过90.7%。值得注意的是，DMEP-LHCE的安全性比TEP-LHCE有所提高，这表明其在下一代锂金属电池中的多功能性和潜力。
