Recognizing the Mechanism of Sulfurized Polyacrylonitrile Cathode Materials for Li–S Batteries and beyond in Al–S Batteries

Abstract

Sulfurized polyacrylonitrile (SPAN) is the most promising cathode for next-generation lithium−sulfur (Li−S) batteries due to the much improved stability. However, the molecular structure and reaction mechanism have not yet been fully understood. Herein, we present a new take on the structure and mechanism to interpret the electrochemical behaviors. We find that the thiyl radical is generated after the cleavage of the S−S bond in molecules in the first cycle, and then a conjugative structure can be formed due to electron delocalization of the thiyl radical on the pyridine backbone. The conjugative structure can react with lithium ions through a lithium coupled electron transfer process and form an ion-coordination bond reversibly. This could be the real reason for the superior lithium storage capability, in which the lithium polysulfide may not be formed. This study refreshes current knowledge of SPAN in Li−S batteries. In addition, the structural analysis is applicable to analyze the current organic cathodes in rechargeable batteries and also allows further applications in Al−S batteries to achieve high performance.

Solid‐State Lithium–Sulfur Battery Enabled by Thio‐LiSICON/Polymer Composite Electrolyte and Sulfurized Polyacrylonitrile Cathode

“…Subsequently, researchers proposed that the conjugated PAN polymer backbones can form delocalized radicals, to activate the formed Li 2 S to reconnect to PAN polymer backbones during the charging process 59,60. However more recently, instead of a general belief of the lithiation of S in S/PAN, extra Li storage mechanisms such as at C, N in S/PAN polymer structures were discovered 61,62. To the best of our knowledge, this is the first report concerning the S/PAN characterization in a solid‐state battery configuration.…”

Long Cycle Life Organic Polysulfide Catholyte for Rechargeable Lithium Batteries

“…The electronic structure is vital factor affecting the electrochemical behavior of organic electrodes . With the elongation of the sulfur chain of Py 2 S 2 to that of Py 2 S 8 ( Figure a), the lowest unoccupied molecular orbital (LUMO) energies show a gradient decrease from −0.06 eV (Py 2 S 2 ) to −1.09 eV (Py 2 S 7 ), although Py 2 S 8 displays a bit higher energy level of −0.97 eV.…”

Highly Efficient and Stable Inorganic Perovskite Quantum Dots by Embedding into a Polymer Matrix

“…The all-inorganic perovskite quantum dots (QDs) of the formula CsPbX 3 (X = Cl, Br, I) have specifically attracted considerable attention due to their narrow emission line width, size-dependent luminescence behavior, covering the visible to near infrared range (400-800 nm), as well as superior photoluminescence quantum yield (PL QY). [1][2][3][4][5][6][7][8][9][10][11][12][13] These advantages make them the ideal candidates for light-emitting diode (LED), lasers, solar cells, and photodetector. [13][14][15][16] In spite of the remarkable advantages of the perovskite QDs, there are still some drawbacks that hindering their practical applications.…”