Wang Yan, Ren Longtao, Zhang Qiaoli, Pato Abdul Hameed, Liu Jun, Lu Xiwen, Liu Wen
College of Chemistry, State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
ACS Appl Mater Interfaces. 2024 Sep 11;16(36):47674-47682. doi: 10.1021/acsami.4c10028. Epub 2024 Aug 30.
The practical application of lithium metal anodes is significantly impeded by poor interfacial stability and uncontrolled dendrite growth. Herein, we introduce methyl trifluoroacetate (MTFA), a low-melting-point small molecule, as an electrolyte additive in an ether-based electrolyte. This additive facilitates the formation of an in situ composite solid electrolyte interphase (SEI) layer that is rich in LiF and features an ester-based flexible matrix. The resulting composite layer exhibits high ionic conductivity and mechanical stability, effectively regulating the lithium deposition behavior over a broad temperature range and inhibiting dendrite formation. Based on MTFA, the Li||Li symmetrical cell achieves a lifespan exceeding 5000 h at room temperature and 800 h at -20 °C, both with ultralow overpotential and exceptional cycling stability. In Li||LiFePO full cells with a high-area loading (10.52 mg cm) and an N/P ratio of 1.68, an average capacity decay of merely 0.096% per cycle is observed over 200 cycles. Even at -20 °C, the Li||LiFePO cell shows a CE of over 99% and maintains stable cycling performance. This work provides an innovative approach for optimizing lithium metal anode interfaces and enhancing low-temperature operation capabilities through the use of electrolyte additives.
锂金属负极的实际应用受到界面稳定性差和枝晶生长不受控制的严重阻碍。在此，我们引入三氟乙酸甲酯（MTFA），一种低熔点小分子，作为醚基电解质中的电解质添加剂。这种添加剂有助于形成富含LiF且具有酯基柔性基质的原位复合固体电解质界面（SEI）层。所得复合层具有高离子电导率和机械稳定性，在很宽的温度范围内有效调节锂沉积行为并抑制枝晶形成。基于MTFA，Li||Li对称电池在室温下寿命超过5000小时，在-20°C下寿命为800小时，均具有超低过电位和出色的循环稳定性。在高面积负载（10.52 mg cm）和N/P比为1.68的Li||LiFePO全电池中，在200次循环中观察到平均每次循环的容量衰减仅为0.096%。即使在-20°C下，Li||LiFePO电池也显示出超过99%的库仑效率并保持稳定的循环性能。这项工作通过使用电解质添加剂为优化锂金属负极界面和增强低温操作能力提供了一种创新方法。
