Xue Yejuan, Wang Yueda, Zhang Heng, Kong Weilong, Zhou Yuxin, Kang Bo, Huang Zhimei, Xiang Hongfa
School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, China.
Angew Chem Int Ed Engl. 2025 Jan 10;64(2):e202414201. doi: 10.1002/anie.202414201. Epub 2024 Nov 2.
Fluorinated-ethers are promising electrolyte solvents in lithium metal batteries, for their high antioxidant and excellent reductive stability on Li anode. However, fluorinated-ethers with high fluorination degree suffer from low ionic conductivity and narrow temperature adaptibility. Herein, we synthesize a mono-fluorinated linear ether of bis(2-fluoroethoxy) methane (BFME) with enhanced solvated ability. The -OCHO- structure and fluoride substitution on the β-C position endows the BFME electrolyte with moderate affinity to Li, thereby improving the ionic conductivity and decreasing the Li-desolvation energy barrier at a wide temperature range of -60-60 °C. Additionally, the electrolyte with anion-participated solvation structure demonstrates high film-forming ability by forming LiF-rich interfacial film on the electrode surfaces, rendering the graphite anode with an initial Coulombic efficiency (CE) of 94.9 % and a Li plating/stripping CE of 99.8 % by Aurbach method. Consequently, the Graphite||LiFePO pouch cells delivered 83.2 %, 92.5 % and 81.2 % capacity retention after 1250, 200 and 300 cycles at 25, -20 °C and 60 °C, respectively. Moreover, the Li||LFP pouch cell with 3 Ah capacity can operate for 65 cycles with 99 % capacity retention, verifying the effectiveness of the BFME electrolyte in stabilizing the interfaces and broadening the temperature adaptibility of lithium-ion and lithium metal batteries.
氟化醚因其高抗氧化性和对锂金属负极优异的还原稳定性，在锂金属电池中是很有前景的电解质溶剂。然而，高氟化程度的氟化醚存在离子电导率低和温度适应性窄的问题。在此，我们合成了一种具有增强溶剂化能力的单氟线性醚双（2-氟乙氧基）甲烷（BFME）。β-C位上的-OCHO-结构和氟取代赋予BFME电解质对锂适度的亲和力，从而在-60至60°C的宽温度范围内提高离子电导率并降低锂去溶剂化能垒。此外，具有阴离子参与溶剂化结构的电解质通过在电极表面形成富含LiF的界面膜表现出高成膜能力，采用Aurbach方法使石墨负极的初始库仑效率（CE）达到94.9%，锂电镀/剥离CE达到99.8%。因此，石墨||磷酸铁锂软包电池在25°C、-20°C和60°C下分别经过1250、200和300次循环后，容量保持率分别为83.2%、92.5%和81.2%。此外，容量为3 Ah的锂||磷酸铁锂软包电池可运行65次，容量保持率为99%，验证了BFME电解质在稳定界面和拓宽锂离子电池及锂金属电池温度适应性方面的有效性。
