Influence of C–S interactions on the electrochemical performance of –COOH functionalized MWCNT/S composites as lithium-sulfur battery cathode

Abstract

Effective trapping of polysulfides within the carbon cathode host strongly depends on intrinsic C-S interactions. We report herein a systematic study of the influence of S-loading process on C-S interactions in MWCNT/S composites prepared by three commonly used industry-friendly methods, namely, mechanical solidstate mixing, infiltration method from a solution of S in CS 2 , and chemical deposition by disproportionation reaction of sodium sulfide and sodium thiosulfate. FESEM and TEM studies reveal strikingly different morphologies of the resulting MWCNT/S composites. XPS and Raman studies indicate different extents of recovery of π bonds in MWCNT due to varying degrees of C-S interfacial interactions in the composites. Furthermore, it is found that the C/O atomic ratio in the composites plays a crucial role: the higher the C/O value the better is the S-confinement. These subtle physical changes induced by C-S interactions in the composites can be related to electrochemical performance when tested in Li-S coin cells. It is found that the best results (high initial capacity of 1143 mAh g −1 and better capacity retention) could be achieved when the solution infiltration method was used for S-loading. This conclusion is further validated by using activated carbon as S-host.

Carbonaceous Materials Investigated by Small-Angle X-ray and Neutron Scattering

“…Electrodes of supercapacitors [1][2][3][4][5][6][7][8][9] and batteries [10][11][12][13][14][15][16][17] are often made of partially ordered carbon powders. For instance, carbide-derived carbons (CDC) are central for the design of supercapacitors [3,6,[18][19][20][21][22] because the pore size and specific surface area can be adjusted by proper choice of the chlorination temperature [6,[23][24][25][26].…”

A Wearable Electrochemical Biosensor Utilizing Functionalized Ti3C2Tx MXene for the Real-Time Monitoring of Uric Acid Metabolite

“…− group in PyTS. 32,33 It is further verified the successful formation of Ti 3 C 2 T x with PyTS molecules.…”

“…The S 2p spectrum of Ti 3 C 2 T x clearly indicates the absence of peaks. In contrast, the S 2p spectrum of PyTS@Ti 3 C 2 T x can be fitted with two characteristic peaks at 166.8 (S 2p3/2) and 168.3 eV (S 2p1/ 2), respectively, which originate from the typical spin−orbit doublets of the −SO 3− group in PyTS 32,33. It is further verified the successful formation of Ti 3 C 2 T x with PyTS molecules.Electrochemical Behaviors of PyTS@Ti 3 C 2 T x Modified Electrode.…”

Self‐Assembled Networks for Regulating Lithium Polysulfides in Lithium‐Sulfur Batteries

“…According to the result of C 1 s spectrum in X‐ray photoelectron spectroscopy (XPS), we can identify the signal of C−Cl bond in 25DCP (286.3 eV) [29] (Figure 1c). No corresponding signal of C−Cl bond is observed for the washed precipitate; instead, a peak ascribed to C−S bond (285.6 eV) [30] can be clearly observed (Figure 1d). Although 25DCP combined with Li 2 S 6 generates an insoluble protective network, the number of C−S bonds is significantly less than that of C−C bonds.…”