Na-based layered iron-manganese oxide Na0.67Fe0.5Mn0.5O2 containing only low-cost elements is a promising cathode for Na-ion batteries used in large-scale energy storage systems.However,the poor cycle stability restricts its practical application.The capacity decay of Na0.67Fe0.5Mn0.5O2 mainly origi-nates from the irreversible anionic redox reaction charge compensation due to the high-level hybridiza-tion between oxygen and iron.Herein,we rationally design a surface Ti doping strategy to tune the anionic redox reaction activity of Na0.67Fe0.5Mn0.5O2 and improve its Na-storage properties.The doped Ti ions not only enlarge the Na migration spacing layer but also improve the structure stability thanks to the strong Ti-O bond.More importantly,the d0-shell electronic structure of Ti4+can suppress the charge transfer from the oxidized anions to cations,thus reducing the anionic redox reaction activity and enhancing the reversibility of charge compensation.The modified Na0.67Fe0.5Mn0.5O2 cathode shows a reversible capacity of 198 mA h g-1 and an increased capacity retention from 15％to 73％after about 1 month of cycling.Meanwhile,a superior Na-ion diffusion kinetics and rate capability are also observed.This work advances the commercialization process of Na-based layered iron-manganese oxide cathodes;on the other hand,the proposed modification strategy paves the way for the design of high-performance electrode materials relying on anionic redox reactions.

Jianyue Jiao;Kang Wu;Na Li;Enyue Zhao;Wen Yin;Zhongbo Hu;Fangwei Wang;Jinkui Zhao;Xiaoling Xiao

College of Materials Science and Opto-electronic Technology,Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Songshan Lake Materials Laboratory,Dongguan 523808,Guangdong,China;Spallation Neutron Source Science Center,Dongguan 523803,Guangdong,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

能源化学

[1]Jianyue Jiao;Kang Wu;Na Li;Enyue Zhao;Wen Yin;Zhongbo Hu;Fangwei Wang;Jinkui Zhao;Xiaoling Xiao-.Tuning anionic redox activity to boost high-performance sodium-storage in low-cost Na0.67Fe0.5Mn0.5O2 cathode)[J].能源化学,2022(10):214-222

67Fe0,Ti4+can

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