Carbon disulfide: A redox mediator for organodisulfides in redox flow batteries.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35622888.
- Also identified by DOI 10.1073/pnas.2202449119 and PMC identifier 9295769.
- Licence recorded as CC BY-NC-ND.
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Abstract
Organodisulfides (RSSR) are a class of promising active materials for redox flow batteries (RFBs). However, their sluggish kinetics and poor cyclic stability remain a formidable challenge. Here, we propose carbon disulfide (CS<sub>2</sub>) as a unique redox mediator involving reversible C-S bond formation/breakage to facilitate the reduction reaction of organodisulfides in RFBs. In the discharge of RSSR, CS<sub>2</sub> interacts with the negatively charged RSSR<sub>-•</sub> to promote cleavage of the S-S bond by reducing about one-third of the energy barrier, forming RSCS<sub>2</sub>Li. In the recharge, CS<sub>2</sub> is unbonded from RSCS<sub>2</sub>Li while RSSR is regenerated. Meanwhile, the redox mediator can also be inserted into the molecular structure of RSSR to form RSCS<sub>2</sub>SR/RSCS<sub>2</sub>CS<sub>2</sub>SR, and these new active materials with lower energy barriers can further accelerate the reaction kinetics of RSSR. With CS<sub>2</sub>, phenyl disulfide exhibits an exceptional rate capability and cyclability of 500 cycles. An average energy efficiency of >90% is achieved. This strategy provides a unique redox-mediating pathway involving C-S bond formation/breakage with the active species, which is different from those used in lithium-oxygen or other batteries.