College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong518060, China.
College of Energy Engineering, Zhejiang University, Hangzhou310058, China.
ACS Appl Mater Interfaces. 2022 Dec 7;14(48):53788-53797. doi: 10.1021/acsami.2c15452. Epub 2022 Nov 28.
Low cycling Coulombic efficiency (CE) and messy Li dendrite growth problems have greatly hindered the development of anode-free Li-metal batteries (AFLBs). Thus, functional electrolytes for uniform lithium deposition and lithium/electrolyte side reaction suppression are desired. Here, we report a locally fluorinated electrolyte (LFE) medium layer surrounding Cu foils to tailor the chemical compositions of the solid-electrolyte interphase (SEI) in AFLBs for inhibiting the immoderate Li dendrite growth and to suppress the interfacial reaction. This LFE consists of highly concentrated LiTFSI dissolved in a fluoroethylene carbonate and/or succinonitrile plastic mixture. The CE of Cu||LiNiCoMnO (NCM811) AFLB increased to a high level of 99% as envisaged, and the cycling ability was also highly improved. These improvements are facilitated by the formation of a uniform, dense, and LiF-rich SEI. LiF possesses high interfacial energy at the LiF/Li interface, resulting in a more uniform Li deposition process as proved by density functional theory (DFT) calculation results. This work provides a simple yet utility tech for the enhancement of future high-energy-density AFLBs.
低循环库仑效率 (CE) 和杂乱的锂枝晶生长问题极大地阻碍了无阳极锂金属电池 (AFLB) 的发展。因此，需要具有均匀锂沉积和抑制锂/电解质副反应功能的电解质。在这里，我们报告了一种局部氟化电解质 (LFE) 中间层，它围绕着铜箔，以调整 AFLB 中固体电解质界面 (SEI) 的化学成分，从而抑制过度的锂枝晶生长并抑制界面反应。这种 LFE 由高浓度的 LiTFSI 溶解在氟代碳酸乙烯酯和/或丁二腈塑料混合物中组成。正如预期的那样，Cu||LiNiCoMnO (NCM811) AFLB 的 CE 增加到了 99%的高水平，并且循环能力也得到了极大的提高。这些改进是通过形成均匀、致密和富含 LiF 的 SEI 来实现的。LiF 在 LiF/Li 界面处具有高界面能，正如密度泛函理论 (DFT) 计算结果所证明的那样，这导致了更均匀的锂沉积过程。这项工作为未来高能密度 AFLB 的增强提供了一种简单而实用的技术。
