All-iron sodium-ion full-cells assembled via stable porous goethite nanorods with low strain and fast kinetics. (June 2019)

• Record Type: Journal Article
• Authors: Huang, Yongxin; Xie, Man; Wang, Ziheng; Jiang, Ying; Huang, Qianming; Bai, Xuedong; Li, Li; Wu, Feng; Chen, Renjie
• Is Part Of: Nano energy. Volume 60(2019)
• Page Start: 294
• Page End: 304
• Publication Date: 2019-06
• Subjects: Sodium-ion batteries -- Anodes -- FeOOH -- Low-strain -- Incomplete conversion reaction; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.03.058
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Iron-based hydroxyl oxides can be regarded as feasible electrodes for sodium-ion batteries due to the simple preparation and rich resources. Goethite nanorod clusters that are wrapped by multi-walled carbon nanotubes with an open tunnel structure exhibit a considerable capacity, a favourable durability and an excellent rate capability within loose working conditions. The structural and electrochemical stability of this anode can be maintained when exposed at ambient environment after 30 days. Moreover, this anode coupled with high-quality Prussian blue cathode delivers feasible energy density of 60 W h kg −1 calculated on the basis of the pouch cell. Abundant voids formed by Kirkendall effect in nanorods allow for the simultaneous promotion of electrolyte infiltration, ion transfer and the pseudocapacitive effect. According to a series of ex situ and in situ measurements, the intercalation and conversion reactions for sodium storage have been revealed and low-volume deformation was observed during the sodiated/desodiated process. In particular, the existence of Nax FeOOH, Fe, NaOH and Na2 O species at fully discharged state indicates an incomplete conversion reaction, resulting in steerable volume expansion and high ionic/electrical conductivity. The advanced sodium storage kinetics can be attributed to the moderate diffusion barrier and remarkable pseudocapacitive effect. Graphical abstract: Innovatively, a low-strain and high-capacity anode was developed by building porous nanorods cluster and incomplete conversion reaction. After fully discharged, a volume expansion of only 35% can be intuitively observed by in-situ TEM images. Moreover, the outstanding rate performance has been achieved via the significant pseudocapacitive contribution and fast tunnel-type diffusion path for Na + ions.Image 1 Highlights: Porous α-FeOOH nanorods and clusters are synthetized via a one-pot hydrothermal method. The MWCNTs are introduced into the active materials to construct a 3D conductive network. The remarkable pseudocapacitive effect is conducive to the rate performance. The incomplete conversion for sodium storage at low voltage is revealed by the ex situ XANES test. The sodium storage process with low-strain and high stability is observed by the in situ TEM image.