Capacity Retention Analysis in Aluminum-Sulfur Batteries

Abstract
The electrochemical performance of aluminum-sulfur batteries is beset by poor stability and sluggish charge-storage properties. To address these issues, carbon allotropes have been used as electrode fillers, but successful outcomes remain inexplicably elusive. Here, a composite of sulfur and small-diameter single-walled carbon nanotubes was studied as a cathode for AlCl3:[EMIM]-based aluminum batteries. The presence of carbon nanotubes, while enabling a high capacity (1024 mAh g-1) with slower decay and reducing the electrolyte-to-sulfur ratio, is insufficient to fully stabilize the cell's performance. In fact, the main obstacle is in the interaction between sulfur and chloroaluminate ions. As we show, there is a gradual buildup of insoluble and poorly conductive discharge products that inhibit the diffusion of electroactive ions and, ultimately, cause capacity decay. Overall, this work sheds light on the carbon-sulfur-electrolyte interactions and their role on the underlying charge-storage mechanism of aluminum-sulfur batteries.

Citation
Smajic, J., Wee, S., Simoes, F. R. F., Hedhili, M. N., Wehbe, N., Abou-Hamad, E., & Costa, P. M. F. J. (2020). Capacity Retention Analysis in Aluminum-Sulfur Batteries. ACS Applied Energy Materials, 3(7), 6805–6814. doi:10.1021/acsaem.0c00921

Acknowledgements
This work was funded by KAUST (BAS/1/1346-01-01). The authors thank the KAUST Core Labs for technical assistance.

Publisher
American Chemical Society (ACS)

Journal
ACS Applied Energy Materials

DOI
10.1021/acsaem.0c00921

Additional Links
https://pubs.acs.org/doi/10.1021/acsaem.0c00921

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