Flexible Carbon Nanotube–Graphene/Sulfur Composite Film: Free-Standing Cathode for High-Performance Lithium/Sulfur Batteries

Abstract

Flexible lithium batteries with high energy density have recently received tremendous interest due to their potential applications in flexible electronic devices. Herein, we report a novel method to fabricate highly flexible and robust carbon nanotube–graphene/sulfur (CNTs–RGO/S) composite film as free-standing cathode for flexible Li/S batteries with increased capacity and significantly improved rate capability. The free-standing CNTs–RGO/S cathode was able to deliver a peak capacity of 911.5 mAh g–1 sulfur (∼483 mAh g–1 electrode) and maintain 771.8 mAh g–1 sulfur after 100 charge–discharge cycles at 0.2C, indicating a capacity retention of 84.7%, which were both higher than the cathodes assembled without CNTs. Even after 100 cycles, the cathode showed a high tensile strength of 62.3 MPa. More importantly, the rate capability was improved by introducing CNTs. The CNTs–RGO/S cathode exhibited impressive capacities of 613.1 mAh g–1 sulfur at 1C with a capacity recuperability of ∼94% as the current returned to 0.2C. These results demonstrate that the well-designed nanocomposites are of great potential as the cathode for flexible lithium sulfur (Li/S) batteries. Such improved electrochemical properties could be attributed to the unique coaxial architecture of the nanocomposite, in which the evenly dispersed CNTs enable electrodes with improved electrical conductivity and mechanical properties and better ability to avoid the aggregation and ensure the dispersive distribution of the sulfur species during the charge/discharge process.

An Aligned and Laminated Nanostructured Carbon Hybrid Cathode for High‐Performance Lithium–Sulfur Batteries

“…[26] Here,t he areal mass density of sulfur can be flexibly controlled by adjusting the stacking number of CMK-3@S/CNT sheets.T he electrochemical performances for the batteries with the sulfur loads of 1, 5, 10 and 20 mg cm À2 at 0.1 Ca re shown in Figure 4a.A ll of them have astable cyclic performance.Although the specific capacity was slightly decreased with the increasing areal mass density,alarge capacity of nearly 900 mAh g À1 was obtained for 20 mg cm À2 ,which is the highest sulfur load to the best of our knowledge.Acomparison on the specific capacity and sulfur load with the previously reported lithium-sulfur batteries [4,12,14,15,18,19,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] demonstrates am uch higher ability of incorporating more sulfur in this battery (Figure 4b). However,a real mass densities of less than 4mgcm À2 were studied in most reports.…”

Foldable interpenetrated metal-organic frameworks/carbon nanotubes thin film for lithium–sulfur batteries

“…To the best of our knowledge, the cycling and rate performance of S@ HKUST-1/CNT electrode is the best performance among MOFs-based sulfur electrodes13141516171819 (Fig. 3e, Supplementary Table 1) and competitive to those of representative high-performance carbon-based sulfur electrodes5910111234353637383940414243444546474849505152535455 (Supplementary Table 2). The excellent performance is attributed to the following reasons.…”

“…Owing to advanced electrode structure and controlled electrode thickness, this strategy offers an outstanding cell performance, which presents the highest volumetric capacity among the recently reported flexible sulfur cathodes (Fig. 4d, Supplementary Table 3)38394041, revealing a great practical potential for next-generation high power density flexible electronics. However, the cycling performance of sulfur electrodes with high volumetric energy densities can be further improved by finding MOFs with proper entrance pore size, big pore volume and plenty of open metal sites, which not only let solvated Li ions transfer in and out but also allow sulfur species to enter and remain confined in the pore for good inhibition of the polysulfide shuttle.…”

Synergetic effect of synthesized sulfonated polyaniline/quaternized graphene and its application as a high-performance supercapacitor electrode

“…5a, revealed that nanohybrid is consisted of elemental C, N, O and S. The weak N1 s and S2p peaks in the XPS spectrum also confirm the s-PANINa surrounded by q-graphene sheets [42]. The high-resolution XPS spectrum of C1 s peaks centered at 284.8, 285.4, 286.5, 286.5, 288.3 and 291.7 eV, corresponding to carbon species of C-C, C-N, C-O, C=O and p-p*, respectively [43] (Fig.…”