Influence of morphology of monolithic sulfur–poly(acrylonitrile) composites used as cathode materials in lithium–sulfur batteries on electrochemical performance

Abstract

Solvent-induced phase separation (SIPS) and thermally-induced phase separation (TIPS) derived poly(acrylonitrile) (PAN) based monoliths with different morphology and specific surface area were prepared and thermally converted into monolithic sulfur-poly(acrylonitrile) (SPAN) materials for use as active cathode materials in lithium-sulfur batteries. During thermal processing, the macroscopic monolithic structure fully prevailed while significant changes in porosity were observed. Both the monomer content in the precursor PAN-based monoliths and the tortuosity of the final monolithic SPAN materials correlate with the electrochemical performance of the SPAN-based cathodes. Overall, percolation issues predominate. In percolating SPAN-based cathode materials, the specific capacity of the SPAN-based cells increases with decreasing tortuosity. All monolithic SPAN materials provided highly reversible and cycle stable cathodes reaching reversible discharge capacities up to 1330 mA h g sulfur À1 @ 0.25C, 900 mA h g sulfur À1 @ 2C and 420 mA h g sulfur À1 @ 8C.

Mechanistic Insights into the Role of Covalent Triazine Frameworks as Cathodes in Lithium‐Sulfur Batteries

“…The resulting sulfur rich polymer (SPAN) contains up to approx. 55 w% of covalently bound sulfur after washing and shows almost complete sulfur utilization and stable cycling performance in a carbonate electrolyte, thus proving the absence of intermediate polysulfide species …”

“…55 w% of covalently bound sulfur after washing and shows almost complete sulfur utilization and stable cycling performance in a carbonate electrolyte, thus proving the absence of intermediate polysulfide species. [23,24] Covalent triazine frameworks (CTF) recently attained great attention as another promising class of materials for Li/S battery applications. [25][26][27]28,[29][30][31] CTFs are obtained by trimerization of aromatic nitriles under ionothermal conditions in molten ZnCl 2 .…”

Prospect of Sulfurized Pyrolyzed Poly(acrylonitrile) (S@pPAN) Cathode Materials for Rechargeable Lithium Batteries

“…Although the electrical conductivity of sulfur is exponentially enhanced after incorporation into the conductive polymer matrix, the S@pPAN composite has semi-conducting properties with ac onductivity in range of 10 À9 to 10 À4 Scm À1 . [39] To tackle this problem, Wang et al introduced series of carbon materials from precursor preparation. one dimensional (1D) multiwalled carbon nanotube (MWCNT; Figure 4a), 2D graphene oxide sheet (GO; Figure 4b)and 3D graphene microsphere (GNS; Figure 4c)were constructed via in situ polymerization or spraying drying method, respectively.…”

Synthesis of Ionic Dendrimers and Their Potential Use as Electrolytes for Lithium–Sulfur Batteries

“…The composite material shows a high addressability of sulfur (up to 90%) as well as a high C‐rate capability. Also, since there are no long chained polysulfides, the material is compatible with carbonate‐based electrolytes . However, SPAN has a comparably low sulfur content of 40–55 wt%.…”

“…Also, since there are no long chained polysulfides, the material is compatible with carbonate-based electrolytes. [11][12][13][14] However, SPAN has a comparably low sulfur content of 40-55 wt%. One approach to address this drawback is the use of electrochemically active additives, that is, catholytes in the electrolyte like dimethyl trisulfide.…”