Yang Tong, Zhang Wenna, Shen Chunli, Ren Long, Liao Xiaobin, Guo Yaqing, Zhao Yan
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, P. R. China.
Hubei Key Laboratory of Energy Storage and Power Battery, School of Mathematics, Physics and Optoelectronic Engineering, Hubei University of Automotive Technology, Shiyan, 442002, P. R. China.
ChemSusChem. 2024 Oct 21;17(20):e202400604. doi: 10.1002/cssc.202400604. Epub 2024 Jun 10.
The strategic formulation of a compatible electrolyte plays a pivotal role in extending the longevity of lithium-metal batteries (LMBs). Here, we present findings on a partially fluorinated electrolyte distinguished by a subdued solvation affinity towards Li ions and a concentrated anion presence within the primary solvation layer. This distinctive solvation arrangement redirects the focal points of reactions from solvent molecules to anions, facilitating the predominant involvement of anions in the creation of a LiF-enriched solid-electrolyte interphase (SEI). Electrochemical assessments showcase effective Li transport kinetics, diminished overpotential polarization for Li nucleation (28 mV), and prolonged cycling durability in Li||Li cells employing the partially fluorinated electrolyte. When tested in Li||NCM811 cells, the designed electrolyte delivers a capacity retention of 89.30 % and exhibits a high average Coulombic efficiency of 99.80 % over 100 cycles with a charge-potential cut-off of 4.6 V vs. Li/Li under the current density of 0.4C. Furthermore, even at a current density of 1C, the cells maintain 81.90 % capacity retention and a high average Coulombic efficiency of 99.40 % after 180 cycles. This work underscores the significance of weak-solvation interaction in partially fluorinated electrolytes and highlights the crucial role of solvent structure in enabling the long-term stability and high-energy density of LMBs.
兼容电解质的战略配方在延长锂金属电池（LMBs）的寿命方面起着关键作用。在此，我们展示了一种部分氟化电解质的研究结果，其特点是对锂离子的溶剂化亲和力较弱，且在第一溶剂化层中存在高浓度阴离子。这种独特的溶剂化排列将反应的焦点从溶剂分子转移到阴离子上，促进了阴离子在形成富含LiF的固体电解质界面（SEI）中的主要参与。电化学评估显示，采用部分氟化电解质的Li||Li电池具有有效的Li传输动力学、降低的Li成核过电位极化（28 mV）以及延长的循环耐久性。在Li||NCM811电池中进行测试时，所设计的电解质在100次循环中容量保持率为89.30%，在4.6 V（相对于Li/Li）的充电电位截止、0.4C的电流密度下，平均库仑效率高达99.80%。此外，即使在1C的电流密度下，电池在180次循环后仍保持81.90%的容量保持率和99.40%的高平均库仑效率。这项工作强调了部分氟化电解质中弱溶剂化相互作用的重要性，并突出了溶剂结构在实现LMBs的长期稳定性和高能量密度方面的关键作用。
