Facile Synthesis of CoS Nanoparticles Anchored on the Surface of Functionalized Multiwalled Carbon Nanotubes as Cathode Materials for Advanced Li–S Batteries

Abstract

The effects of CoS loading (10, 20, and 30%) on multiwalled carbon nanotubes (MWCNTs) on electrochemical performance for Li−S batteries were investigated. A facile hydrothermal method was used to grow CoS nanoparticles in situ on the surface of MWCNTs. In addition, CoS on functionalized multiwalled carbon nanotubes (f-MWCNTs) was also investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Xray photoelectron spectroscopy were used to characterize the structure and electronic state of CoS on the surface of MWCNTs and f-MWCNTs. The initial discharge capacities and reversible specific capacities after 200 cycles were found to be 980 and 612 mAh/g, 990 and 707 mAh/g, and 959 and 658 mAh/g for the 10, 20, and 30% CoS samples, respectively. Interestingly, the 20% CoS@MWCNTs show the best initial discharge capacity and retention after 200 cycles. This finding can be attributed to the fact that high CoS loading (30%) may not be dispersed evenly on the MWCNT surface, while low CoS loading (10%) leads to fewer CoS and weaker adsorption for polysulfides. Moreover, the 20% CoS/f-MWCNTs show even higher initial discharge capacities of 1103 mAh/g and reversible specific capacities of 796 mAh/g after 200 cycles. This can be attributed to a rougher surface with more active sites on f-MWCNTs for trapping polysulfides and for enhancing the electronic conductivity of the cathode composite. X-ray photoelectron spectroscopy (XPS) spectra show prominent peaks at 162.7 and 163.9 eV, which correspond to Co−S and C−S bonds, respectively, suggesting that CoS bonds well with MWCNTs. It is postulated that CoS/f-MWCNTs play a role in adsorbing lithium polysulfides (LPS) during the charge and discharge process and accelerating the kinetics of polysulfide conversion.

Interfacial Chemical Linkage Enabling MWCNTs/Sb2S3 High Sodium Storage Performance

“…48 The peaks at 285.6 and 286.8 eV were assigned to C−O−Sb and C−S bonding, further demonstrating the successful formation of interfacial bonding between MWCNTs and Sb 2 S 3 . 28,48 The existence of C−S/C−O−Sb bonds also suggests that the defective MWCNTs could effectively anchor Sb 2 S 3 and confine the sodiated sulfides from aggregation. Undoubtedly, the interfacial chemical linkage is profitable for suppressing the interfacial charge transfer impendence and maintaining the structural integrality of the MWCNTs/Sb 2 S 3 -M electrode during repeated charge/discharge processes.…”

“…Another pair of peaks at 162.9 and 161.8 eV were regarded as the Sb–S bond of S 2p 1/2 and S 2p 3/2 . Two peaks at 169.0 and 170.1 eV should be connected with some oxysulfide species. , As for high-resolution C 1s spectrum (Figure d), the position located at 284.8 eV corresponded to the C–C/CC bond of MWCNTs . The peaks at 285.6 and 286.8 eV were assigned to C–O–Sb and C–S bonding, further demonstrating the successful formation of interfacial bonding between MWCNTs and Sb 2 S 3 . , The existence of C–S/C–O–Sb bonds also suggests that the defective MWCNTs could effectively anchor Sb 2 S 3 and confine the sodiated sulfides from aggregation.…”

Sulfur Encapsulation into Carbon Nanospheres as an Effective Technique to Limit Sulfide Dissolution and Extend the Cycle Life of Lithium–Sulfur Batteries

“…The reaction is responsible for the production of subspecies of polysulfides which are highly soluble in organic electrolytes typical of Li-S batteries. Several methods have been proposed to curb the transfer of resistive sulfide species to the anode or their dissolution into the electrolyte: engineering of the carbon surface with functional groups to chemically anchor the polysulfides to the carbon pores [1]; employing catalytic transition metal nitrides, sulfide, or oxides to increase the efficiency of the chain reaction [2,3]; or physical entrapment of sulfur into conductive matrices [4,5] to limit the deposition of resistive lithium sulfides at the anode. Previous efforts have shown that capacity degradation of the lithium-sulfur system stems from the higher discharge plateau [6], since that is where nonrecoverable products of the redox reaction involving long Energies 2024, 17, 2168 2 of 10 chain polysulfide are formed; therefore, efforts to create carbon-sulfur nanocomposites and the confinement of sulfur would cull the full reduction in polysulfide chain products, as wrapped sulfur sites would act as sites with limited lithium reactivity [7][8][9].…”

Cobalt‐based zeolitic imidazole framework derived hollow Co3S4 nanopolyhedrons for supercapacitors

“…They have attracted much attention as potential supercapacitor electrode materials. [7][8][9][10][11][12][13] In particular, cobalt sulfides with high electrical conductivity have been widely studied in many applications due to their excellent electrochemical properties 14 Much work has gone into creating different cobalt sulfide nanostructures over the last 20 years, including nanoparticles 15,16 nanosphere, 17 nanorods, 18,19 nanoarrays, 20 nanoneedles, 21 nanosheets, 22 nanofilms, 23 and hollow nanostructures, [24][25][26][27] for use in electrochemical energy storage systems. Among these structures, hollow nanostructures are expected to deliver superior performance because of the following advantages.…”