Formation Mechanism and Molecular Structure of Sulfurized Polyacrylonitrile.
basic_science · Level V
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- Record sourced from PubMed, PMID 40347024.
- Also identified by DOI 10.1002/adma.202503534.
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Abstract
Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their high theoretical energy density and abundant sulfur resources. Sulfurized polyacrylonitrile (SPAN) effectively suppresses polysulfide dissolution and demonstrates excellent cycling stability, making it a promising candidate for cathode materials in practical Li-SPAN batteries. This study elucidates the formation mechanism, chemical bonds, and spatial structures of SPAN. The reaction begins with the generation of ·S<sub>2</sub>· diradicals, followed by the dehydrogenation and cyclization of polyacrylonitrile (PAN), ultimately resulting in the formation of C─S and N─S bonds. The multilayered structure of SPAN, characterized by C-S and N-S layers twisted at angles of ≈30 to 40 degrees and interconnected by C─S<sub>x</sub>─N bonds, has the potential to chemically confine sulfur up to a maximum of 63.5 wt.%, corresponding to a theoretical capacity exceeding 1000 mAh g<sup>-1</sup>. These findings provide fundamental insights for the design of SPAN materials for advanced X-SPAN batteries.