Park Kyobin, Kim Dong-Min, Ha Kwang-Ho, Kwon Bomee, Lee Jeonghyeop, Jo Seunghyeon, Ji Xiulei, Lee Kyu Tae
School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
The Molecular Foundry and the Joint Center for Energy Storage Research Department, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Adv Sci (Weinh). 2022 Nov;9(33):e2203443. doi: 10.1002/advs.202203443. Epub 2022 Oct 17.
The activity of lithium ions in electrolytes depends on their solvation structures. However, the understanding of changes in Li activity is still elusive in terms of interactions between lithium ions and solvent molecules. Herein, the chelating effect of lithium ion by forming [Li(15C5)] gives rise to a decrease in Li activity, leading to the negative potential shift of Li metal anode. Moreover, weakly solvating lithium ions in ionic liquids, such as [Li(TFSI) ] (TFSI = bis(trifluoromethanesulfonyl)imide), increase in Li activity, resulting in the positive potential shift of LiFePO cathode. This allows the development of innovative high energy density Li metal batteries, such as 3.8 V class Li | LiFePO cells, along with introducing stable biphasic electrolytes. In addition, correlation between Li activity, cell potential shift, and Li solvation structure is investigated by comparing solvated Li ions with carbonate solvents, chelated Li ions with cyclic and linear ethers, and weakly solvating Li ions in ionic liquids. These findings elucidate a broader understanding of the complex origin of Li activity and provide an opportunity to achieve high energy density lithium metal batteries.
电解质中锂离子的活性取决于其溶剂化结构。然而，就锂离子与溶剂分子之间的相互作用而言，对锂活性变化的理解仍然难以捉摸。在此，锂离子通过形成[Li(15C5)]产生螯合效应，导致锂活性降低，从而使锂金属阳极的电位负移。此外，离子液体中弱溶剂化的锂离子，如[Li(TFSI)]（TFSI = 双（三氟甲磺酰）亚胺），锂活性增加，导致磷酸铁锂阴极的电位正移。这使得创新的高能量密度锂金属电池得以开发，如3.8 V级Li | LiFePO电池，同时引入稳定的双相电解质。此外，通过比较碳酸盐溶剂中的溶剂化锂离子、环状和线性醚中的螯合锂离子以及离子液体中弱溶剂化的锂离子，研究了锂活性、电池电位偏移和锂溶剂化结构之间的相关性。这些发现阐明了对锂活性复杂起源的更广泛理解，并为实现高能量密度锂金属电池提供了机会。
