摘要
Oxygen reduction reactions(ORRs)with one-or two-electron-transfer pathways are the essential process for aprotic metal-oxygen batteries,in which the stability of superoxide intermediates/products(O_(2)^(-),LiO_(2),NaO_(2),etc.)mainly dominates the ORR activity/stability and battery performance.However,little success in regulating the stability of the superoxides has been achieved due to their highly reactive characteristics.Herein,we identified and modulated the stability of superoxides by introducing anthraquinone derivatives as cocatalysts which functioned as superoxide trapper adsorbing the superoxides generated via surface-mediated ORR and then transferring them from the solid catalyst surface into electrolyte.Among the studied trappers,1,4-difluoroanthraquinone(DFAQ)with electron-withdrawing groups showed the highest adsorption towards superoxides and could efficiently stabilize LiO_(2)in electrolyte,which greatly promoted the surface-mediated ORR rate and stability.This highlighted the magnitude of adsorption between the trapper and LiO_(2)on the ORR activity/stability.Using an aprotic Li-O_(2)battery as a model metal-O_(2)battery,the overall performance of the cell with DFAQ was substantially improved in terms of cell capacity,rate capability and cyclic stability.These results represent a significant advance in the understanding of ORR mechanisms and promoting the performance of metal-O_(2)batteries.
单电子或双电子氧还原反应(ORR)是非质子型金属-氧气电池的关键过程,其中超氧化物中间体或产物(O_(2)^(-),LiO_(2),NaO_(2)等)的稳定性决定了催化剂的ORR活性/稳定性和电池的整体性能.然而,超氧化物具有高反应活性的特点导致其稳定性难以调控.本文将蒽醌衍生物作为助催化剂,成功实现了超氧化物稳定性的调控.在ORR过程中,该助催化剂首先吸附固体催化剂表面生成的超氧化物,并将其转移至电解液中.研究发现,含吸电子基团的1,4-二氟蒽醌(DFAQ)对超氧化物的吸附强度最高,能最大程度地将LiO_(2)稳定在电解液中,从而大幅提高了表面ORR的反应速率和稳定性.这一结果证明助催化剂对LiO_(2)吸附能的强弱对ORR的活性/稳定性具有重要影响.以锂氧电池作为金属-氧气电池的模型器件,发现DFAQ分子的引入能够显著提高电池的容量、倍率性能和循环稳定性.本工作有助于深入理解ORR反应机制和提高金属-氧气电池的电化学性能.
作者
Hua Wang
Liangliang Liu
Xiao Liu
Yu Jia
Peng Zhang
Yong Zhao
王华;刘亮亮;刘肖;贾瑜;张鹏;赵勇(Key Lab for Special Functional Materials of Ministry of Education,National&Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology,School of Materials Science and Engineering,Collaborative Innovation Center of Nano Functional Materials and Applications,Henan University,Kaifeng 475004,China;Department of Materials Science&Engineering,Shenzhen,Key Laboratory of Solid State Batteries Shenzhen,Guangdong Provincial Key Laboratory of Energy Materials for Electric Power,Southern University of Science and Technology,Shenzhen 518055,China;College of Chemistry and Molecular Sciences,Hubei Key Laboratory of Electrochemical Power Sources,Wuhan University,Wuhan 430072,China)
基金
the National Natural Science Foundation of China(21773055,U1604122,51702086,21203055and 21805070)
the Program for Science&Technology Innovation Talents in Universities of Henan Province(18HASTIT004)
China Postdoctoral Science Foundation(2020M672201)。
