CoS₂-Decorated Cobalt/Nitrogen Co-Doped Carbon Nanofiber Networks as Dual Functional Electrocatalysts for Enhancing Electrochemical Redox Kinetics in Lithium–Sulfur Batteries

Abstract

Lithium sulfur (Li–S) batteries have been considerably studied in energy storage systems because of their extremely high energy density. Nevertheless, poor sulfur utilization and lower sulfur loading, polysulfides shuttling, and short cycling life are the major obstacles to their application. Herein, we present the cubic structure of CoS2 microcrystals decorated on Co/N-codoped carbon nanofibers (denoted as CSCNC) by an electrospinning technique followed by a hydrothermal process. The Li2S6 catholyte was added in the fibrous CSCNC network as the current free electrode for Li–S batteries, which was used as the positive catalyst to restrain the shuttle effect and facilitate the reaction kinetics. Additionally, CoS2 and Co are dual functional electrocatalysts for facilitating lithium sulfide nucleation onto the surface of CSCNC, thus reduce electrochemical polarization and enhance the specific capacity. This CSCNC@Li2S6 electrode exhibits 877 mAh g–1 capacity retention with sulfur loading of 7.11 mg over 200 cycles and has an average decay of 0.11% per cycle. Additionally, the composite electrode with sulfur loading accomplishes up to 14.22 mg, providing 12.7 mAh of extremely high capacity, which is much higher than that of the carbon-based electrodes for Li–S batteries.

Nanosized Ti 4 O 7 supported on carbon nanotubes composite modified separator for enhanced electrochemical properties of lithium sulfur battery

“…It is clear that the oCNTs‐Ti 4 O 7 electrode possesses higher capacity of Li 2 S precipitation than oCNTs, indicating that the Ti 4 O 7 nanoparticles have significant electrocatalytic activity for accelerating conversion of polysulfides. It is attributed to the unique sulfiphilic surface of Ti 4 O 7 , which can considerably reduce the energy barrier of initial nucleation of Li 2 S and facilitate the precipitation for more polysulfides 23 …”

“…It is attributed to the unique sulfiphilic surface of Ti 4 O 7 , which can considerably reduce the energy barrier of initial nucleation of Li 2 S and facilitate the precipitation for more polysulfides. 23 CV measurements of cells were implemented with a sweep rate of 0.1 mV/s and the relevant curves were demonstrated in Figure 4A. For the cell using PE separator in cathodic sweep, two peaks at 2.29 and 1.94 V are observed corresponding to the two-step reductive process.…”

“…These mediators can reduce the interface resistance and increase the transfer rate of electrons and lithium ions. Moreover, the polar surface of metallic oxides is conducive to the nucleation and grain growth of lithium sulfide, facilitating the conversion of polysulfides 23 . However, low electronic conductivity of these metallic oxides would increase internal resistance of battery and cause negative effects on electrochemical performance.…”

“…Moreover, the polar surface of metallic oxides is conducive to the nucleation and grain growth of lithium sulfide, facilitating the conversion of polysulfides. 23 However, low electronic conductivity of these metallic oxides would increase internal resistance of battery and cause negative effects on electrochemical performance. Non stoichiometric titanium oxide (Ti n O 2n−1 ) series have excellent electrical conductivity because of oxygen vacancy in crystal.…”

Transition metal sulfides meet electrospinning: versatile synthesis, distinct properties and prospective applications

“…Through a post-treatment process, metal sulfide nanoparticles can be not only hybridized with electrospun polymer nanofibers, but also carbon and ceramic nanofibers. [74][75][76][77][78][79][80][81][82] Recently, MnS@carbon nanofibers (CNFs) have been prepared via an electrospinning and subsequent carbonization process (Figure 2d). 74 First, continuous MnSO 4 /PAN nanofibers are fabricated as freestanding membrane by electrospinning.…”