Sulfur-Rich Polymers Based Cathode with Epoxy/Ally Dual-Sulfur-Fixing Mechanism for High Stability Lithium–Sulfur Battery

Abstract

Lithium−sulfur (Li−S) batteries have attracted a great deal of attention for the next-generation energy storage devices due to their inherently high theoretical energy density, high natural abundance, and low cost. However, the dissolution of polysulfides in electrolytes and their undesirable shuttle behavior lead to poor cycling performance, which obstructs practical application. Herein, we report a dual-sulfur-fixing mechanism of epoxy/allyl compound/sulfur system to prepare poly(sulfur-random-4-vinyl-1,2-epoxycyclohexane) (SVE) copolymers as powerful cathode materials. Benefiting from the stable C−S bond and a uniform distribution of ultrafine Li 2 S/S 8 in the SVE-based polymer matrix, the SVE electrodes exerted an embedding effect to reduce polysulfides migration. The thiosulfate/polythionate protective layer derived from the terminal hydroxyl group of SVE also ensured the cycle stability of SVE electrodes during cycling. As a result, optimized SVE electrodes deliver a high reversible specific capacity of 1248 mA h g −1 at rates of 0.1 C, together with a stable cycling performance of no capacity decay per cycle over more than 400 cycles. This work provides an effective strategy for the practical application of organosulfur polymers Li−S batteries and inspires the exploration of the reaction mechanism of epoxy/allyl compound/sulfur system.

Enhanced Polysulfide Conversion with Highly Conductive and Electrocatalytic Iodine‐Doped Bismuth Selenide Nanosheets in Lithium–Sulfur Batteries

“…[ 31–36 ] However, cathodes based on metal sulfides are generally characterized by moderate electrical conductivities, limited sulfur utilization, insufficient cycling stability, and low rate capabilities. [ 37–41 ]…”

Copolymerization of Sulfur Chains with Vinyl Functionalized Metal−Organic Framework for Accelerating Redox Kinetics in Lithium−Sulfur Batteries

“…Recently, copolymerizing elemental sulfur (S 8 ) with organic molecules such as 1,3‐diisopropenylbenzene, divinylbenzene, tetra(allyloxy)‐1,4‐benzoquinone, and 4‐vinyl‐1,2‐epoxycyclohexane (VE) has been proved to be effective in facilitating redox kinetics as well as increasing the Li + transfer rate. [ 34–39 ] Inspired by this, it holds the potential to achieve faster redox kinetics and meanwhile decrease the diffusion of LiPSs by copolymerizing sulfur with MOF via similar inverse vulcanization reaction. Herein, as illustrated in Figure 1 , a MOF‐sulfur copolymer (CNT@UiO‐66‐V‐S) was designed and synthesized, where the sulfur chains were copolymerized with the vinyl functionalized MOFs (UiO‐66‐V).…”

“…[30,33] Therefore, designing MOF-based hosts with improved LiPSs redox kinetics still remains a big challenge and the corresponding mechanism of promoting LiPSs conversion needs to be fully understood as well.Recently, copolymerizing elemental sulfur (S 8 ) with organic molecules such as 1,3-diisopropenylbenzene, divinylbenzene, tetra(allyloxy)-1,4-benzoquinone, and 4-vinyl-1,2-epoxycyclohexane (VE) has been proved to be effective in facilitating redox kinetics as well as increasing the Li + transfer rate. [34][35][36][37][38][39] Inspired by this, it holds the potential to achieve faster redox kinetics and meanwhile decrease the diffusion of LiPSs by copolymerizing sulfur with MOF via similar inverse vulcanization Lithium−sulfur batteries (LSBs) are regarded as one of the most promising candidates for energy storage devices. However, the severe shuttling effect of soluble polysulfides (PSs) limits its further application.…”

Ni‐CeO2 Heterostructures in Li‐S Batteries: A Balancing Act between Adsorption and Catalytic Conversion of Polysulfide

“…The linear relationship between the peak current density ( I peak ) and the square root scanning rate ( v 0.5 ) is expressed by the Randles–Sevcik equation: I p = (2.65 × 10 5 ) n 1.5 SD Li+ 0.5 Δ C Li+ v 0.5 , where n denotes the number of transfer charges, S denotes the surface area of the active electrode, D Li+ denotes the diffusion coefficient of Li ions, and Δ C Li+ denotes the concentration of Li ions. [ 43 ] The peak currents at the square root of different scan rates are shown in Figure 4e . The slopes of the S@CNF, S@CeO 2 ‐CNF, and S@Ni‐CeO 2 ‐CNF curves are 2.18, 3.11, and 5.83, respectively, at peak 1; 1.10, 1.40, and 2.28, respectively, at peak 2; and 0.98, 2.27, and 2.98, respectively, at peak 3.…”