Hierarchical Porous Carbon Cathode for Lithium–Sulfur Batteries Using Carbon Derived from Hybrid Materials Synthesized by Twin Polymerization

Abstract

A new route of fabrication of cathodes for lithium–sulfur (Li–S) batteries with high cycle stability is reported. The cathodes are fabricated using porous carbon materials obtained from hybrid materials synthesized by twin polymerization on sulfonated polystyrene microparticles. The sulfonic acid groups act as room temperature catalyst for twin polymerization resulting in the formation of nanostructured phenolic resin/silica hybrid materials on the surface of sulfonated polystyrene particles. The shell formed by phenolic resin is transformed into carbon by simple pyrolysis and the polystyrene core is decomposed simultaneously at the pyrolysis temperature yielding porous carbon/silica nanocomposite hollow spheres. After silica removal, a hierarchical, highly porous carbon is obtained. Melt mixing of the carbon with sulfur is used for the fabrication of cathodes for Li–S batteries. The presence of silica on one hand imposes strength to the sphere wall during the carbonization and depolymerization of polystyrene, and on the other hand generates microporous carbon material for lithium–sulfur batteries. The nanostructured hybrid cathode allows very high capacity of 800–1000 mAh gsulfur −1 and remarkable reversible cycling stability and rate capability over 200 cycles at 0.1C rate and over 440 cycles at 1C rate for Li–S batteries.

Graphene Oxide Induced Growth of Nitrogen‐Doped Carbon Nanotubes as a 1D/2D Composite for High‐Performance Lithium‐Sulfur Batteries

“…The I D /I G value decreases from 1.23 for NCNTs to 0.94 for NCNTs‐G, indicating enlarged graphitic domains in the latter, which is beneficial for electron transport . The undetectable Raman characteristic bands may be due to strong absorption of sulfur in the NCNTs, the small domain sizes of sulfur and the its inherent instability toward Raman laser ,. After sulfur loading, the characteristic bands of sulfur disappear in NCNTs/S and NCNTs‐G/S, indicating that sulfur is uniformly dispersed within the carbon matrix.…”

Boosting High-Performance in Lithium–Sulfur Batteries via Dilute Electrolyte

“…Porous carbons and polar inorganic compounds with different nano-architectures have been widely employed as S or Li 2 S hosts. 21,[26][27][28][29][30][31][32][33] Optimizations of both liquid and solid electrolytes have proved to be particularly effective in enhancing the cyclability of a broad range of S/Li 2 S cathodes. 23,[34][35][36][37] So far, organic liquid electrolytes and their fundamental studies dominate the mainstream due to their high ionic conductivity.…”

Material design and structure optimization for rechargeable lithium-sulfur batteries

“…The porous carbon hosts can greatly enhance the electronic conductivity of sulfur electrodes, accommodate huge volume change of sulfur species, and immobilize soluble polysulfides. So far, various porous carbons with different dimensions, such as zero-dimensional (0D) hollow carbon spheres, [93][94][95][96][97][98] multi-shell carbon spheres, [99][100][101] hierarchical porous carbon spheres, [102][103][104][105] 1D carbon tubes and carbon fibers, [106][107][108][109][110] 2D graphene and carbon sheets, [111][112][113][114][115] and 3D carbon frameworks, [116][117][118] have been extensively investigated (Figure 4A). In a representative example, inspired by the structure of old-fashioned photo albums, the 2D yolk-shell carbon nanosheets were synthesized to construct a novel freestanding sulfur cathode with a high sulfur loading of 5 mg cm À2 and a high sulfur content of 73 wt %, which can deliver an areal capacity of 5.7 mAh cm À2 and a volumetric capacity of 1,330 mAh cm À3 .…”