Mesoporous carbon prepared by etching halloysite nanotubes (HNTs) with pyrrole as a precursor for a sulfur carrier of superior lithium–sulfur batteries

Abstract

Using pyrrole as a carbon precursor and halloysite nanotubes (HNT) as a templating agent, mesoporous carbon (MC) was prepared by template etching and combined with sulfur as a composite cathode for lithium–sulfur batteries.

Synthesis and Electrochemical Performance of Graphene @ Halloysite Nanotubes/Sulfur Composites Cathode Materials for Lithium-Sulfur Batteries

“…The Nyquist plots should be composed of a small intercept at high frequency, two semicircles at medium and high frequency and a straight line at low frequency. The intercept with the axis is the internal resistance (Ra) of the battery; the contact resistance (Rb) in the high frequency region is divided into the electrolyte/electrode interface and electrolyte/SEI layer interface and the slope of the straight line in the low frequency region is the diffusion resistance (Rc) [ 26 ]. It is exhibiting that the diameter of RGO@HNTs-80/S is the smallest in the high frequency half circle, the diameters of HNTs-80/S and HNTs-90/S are centered, while the diameter of S electrode is largest in the high frequency half circle.…”

“…The peaks at around 2.29 V corresponds to the reduction of S8 to higher-order polysulfides (Li 2 S x , 4 ≤ x < 8). The second peak at 1.94 V can be attributed to the further reduction of the higher-order polysulfides to insoluble Li 2 S or Li 2 S 2 [ 26 ]. In the subsequent anodic scan process, a sharp oxidation peaks at 2.49 V were observed and can be attributed to the conversion of Li 2 S and polysulfides into S 8 .…”

“…In the synthesis of composite electrode materials, the surface modification of HNTs with PVP does not damage the structure of HNTs, but also overcomes the characteristics of surface inertia and easy agglomeration, which can effectively improve the dispersibility of HNTs [ 33 , 34 ]. Then HCl (2.4 mL, 10 M) was added to the above aqueous solution [ 26 ]. After reaction for 3 h, the HNTs/S composites were washed with ethanol and water, separated centrifugally, and dried under vacuum for 12 h.…”

“…The mesoporous structure in the composite electrode of lithium-sulfur batteries can effectively improve the sulfur load of cathode material. Liu [ 26 ] used pyrrole as a carbon precursor and HNTs as the templating agent. Mesoporous carbon (MC) was prepared by template etching and combined with sulfur as a composite cathode for lithium-sulfur battery.…”

A diatomite-derived N-doped carbon aerogel with 98% sulfur loading for the enhancement of Li–S battery performance

“…Compared with C PDA /DT@S, the oxidation peak potential near 2.3 V is high, close to 2.4 V. The oxidation of Li 2 S and Li 2 S 2 to long-chain Li 2 S n has a more robust reaction dynamics. 30 Five cycles of cyclic voltammetry scanning were carried out, the peak I C1 gradually moved higher (from 1.9 V of 1st to 2.0 V of 5th), and the peak I C1 gradually moved lower (from 2.4 V of 1st to 2.3 V of 5th), which means that the catalytic effect of C PDA /DT took a gradual effect, accelerating the reduction process from long-chain polysulfide to short-chain polysulfide and the oxidation process of S 8 . The value of the I C1 peak gradually increased, and the reaction dynamics were gradually accelerated.…”