Issue 38, 2022

Guest water hinders sodium-ion diffusion in low-defect Berlin green cathode material

Abstract

Among Prussian blue analogues (PBAs), NaxFe[Fe(CN)6]1−y·nH2O is a highly attractive cathode material for sodium-ion batteries due to its high theoretical capacity of ∼170 mA h g−1 and inexpensive raw materials. However, concerns remain over its long-term electrochemical performance and structural factors which impact sources of resistance in the material and subsequently rate performance. Refined control of the [Fe(CN)6] vacancies and water content could help in realizing its market potential. In this context, we have studied a low-defect Berlin green (BG) Na0.30(5)Fe[Fe(CN)6]0.94(2)·nH2O with varied water content corresponding to 10, 8, 6, and 2 wt%. The impact of water on the electrochemical properties of BG was systematically investigated. The electrodes were cycled within a narrow voltage window of 3.15–3.8 V vs. Na/Na+ to avoid undesired phase transitions and side reactions while preserving the cubic structure. We demonstrate that thermal dehydration leads to a significantly improved cycling stability of over 300 cycles at 15 mA g−1 with coulombic efficiency of >99.9%. In particular, the electrode with the lowest water content exhibited the fastest Na+-ion insertion/extraction as evidenced by the larger CV peak currents during successive scans compared to hydrated samples. The results provide fundamental insight for designing PBAs as electrode materials with enhanced electrochemical performance in energy storage applications.

Graphical abstract: Guest water hinders sodium-ion diffusion in low-defect Berlin green cathode material

Supplementary files

Article information

Article type
Paper
Submitted
21 7 2022
Accepted
12 9 2022
First published
13 9 2022

Dalton Trans., 2022,51, 14712-14720

Guest water hinders sodium-ion diffusion in low-defect Berlin green cathode material

D. O. Ojwang, L. Häggström, T. Ericsson, R. Mogensen and W. R. Brant, Dalton Trans., 2022, 51, 14712 DOI: 10.1039/D2DT02384A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements