A Long Lifetime Aqueous Organic Solar Flow Battery

Abstract
Monolithically integrated solar flow batteries (SFBs) hold promise as compact stand-alone energy systems for off-grid solar electrification. Although considerable research is devoted to studying and improving the round-trip efficiency of SFBs, little attention is paid to the device lifetime. Herein, a neutral pH aqueous electrolyte SFB with robust organic redox couples and inexpensive silicon-based photoelectrodes is demonstrated. Enabled by the excellent stability of both electrolytes and protected photoelectrodes, this SFB device exhibits not only unprecedented stable continuous cycling performance over 200 h but also a capacity utilization rate higher than 80%. Moreover, through comprehensive study on the working mechanisms of SFBs, a new theory based on instantaneous solar-to-output electricity efficiency toward more optimized device design is developed and a significantly improved solar-to-output electricity efficiency of 5.4% from single-junction silicon photoelectrodes is realized. The design principles presented in this work for extending device lifetime and boosting round trip energy efficiency will make SFBs more competitive for off-grid applications.

Citation
Li, W., Kerr, E., Goulet, M., Fu, H., Zhao, Y., Yang, Y., … Jin, S. (2019). A Long Lifetime Aqueous Organic Solar Flow Battery. Advanced Energy Materials, 9(31), 1900918. doi:10.1002/aenm.201900918

Acknowledgements
This research was supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR-2017-CRG6-3453.02. H.-C.F. and J.-H.H. were supported by KAUST baseline fund for design and fabrication of single junction Si solar cells. Research at Harvard was supported by the U.S. National Science Foundation through Grant No. NSF CBET-1509041.

Publisher
Wiley-VCH Verlaginfo@wiley-vch.de

Journal
Advanced Energy Materials

DOI
10.1002/aenm.201900918

Additional Links
https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.201900918https://rss.onlinelibrary.wiley.com/doi/am-pdf/10.1002/aenm.201900918

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