Sun Guiru, Gao Rui, Jiao Hailiang, Luo Dan, Wang Yan, Zhang Zexu, Lu Wei, Feng Ming, Chen Zhongwei
Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Changchun, 130103, China.
Department of Chemical Engineering, Waterloo Institute for Nanotechnology, Waterloo Institute for Sustainable Energy, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
Adv Mater. 2022 Oct;34(40):e2201838. doi: 10.1002/adma.202201838. Epub 2022 Sep 2.
The major challenges for Li-O batteries are sluggish reaction kinetics and large overpotentials due to the cathode passivation resulting from insulative and insoluble Li O . Here, a novel nanodot (ND)-modified electrolyte is designed by employing cobalt bis(trifluoromethylsulfonyl)imide (Co(TFSI) ) as an electrolyte additive. The Co(TFSI) additive can react with discharge intermediate LiO and product Li O to form CoO NDs. The generated CoO NDs are well dispersed in electrolyte, which integrates both the high catalytic activity of solid catalyst and the good wettability of soluble catalyst. Under the catalytis of CoO NDs, Li O is produced and deposits on the cathode together with them. At the recharge process, these well dispersed CoO NDs help to decompose solid Li O at a lower overpotential. The Li-O cells with Co(TFSI) exhibit a long cycle life of 200 cycles at a current density of 200 mA g under a cutoff capacity of 1000 mAh g , as well as a superior reversibility associated with the Li O formation and decomposition. The study is expected to broaden the range of electrolyte additives and provide a new view to developing highly dispersed NDs-based catalysts for Li-O batteries.
锂氧电池面临的主要挑战是反应动力学迟缓以及由于绝缘且不溶性的Li₂O导致的阴极钝化而产生的大过电位。在此，通过使用双（三氟甲基磺酰）亚胺钴（Co(TFSI)₂）作为电解质添加剂，设计了一种新型的纳米点（ND）修饰电解质。Co(TFSI)₂添加剂可与放电中间体LiO₂和产物Li₂O反应形成CoO₂ ND。生成的CoO₂ ND很好地分散在电解质中，它兼具固体催化剂的高催化活性和可溶性催化剂的良好润湿性。在CoO₂ ND的催化作用下，Li₂O生成并与它们一起沉积在阴极上。在充电过程中，这些分散良好的CoO₂ ND有助于在较低过电位下分解固体Li₂O。含有Co(TFSI)₂的锂氧电池在200 mA g⁻¹的电流密度、1000 mAh g⁻¹的截止容量下表现出200次循环的长循环寿命，以及与Li₂O形成和分解相关的优异可逆性。该研究有望拓宽电解质添加剂的范围，并为开发用于锂氧电池的高度分散的基于ND的催化剂提供新的视角。
