A sulfur–eugenol allyl ether copolymer: a material synthesized via inverse vulcanization from renewable resources and its application in Li–S batteries

Abstract

The demand for environmentally friendly and sustainable resources have dramatically increased in scientific and technological areas including energy storage systems and production of new functional materials. Sulfur copolymers with high sulfur contents up to 90 wt% were prepared via inverse vulcanization from environment-friendly, sustainable raw materials: cost-effective waste-product elemental sulfur and eugenol allylether (EAE), which is obtained from clove oil. Thermal properties and electrochemical activities of the resulting poly(S-co-EAE) materials can be tuned by controlling EAE:S feed ratio. Employed as cathode materials in Li-S batteries, the copolymer with 90 wt% sulfur content provides a good cycling stability at the capacity ~650 mAhg -1 and high coulombic efficiencies (> 99 %) over 100 cycles.

Enabling High‐Rate and Safe Lithium Ion–Sulfur Batteries by Effective Combination of Sulfur‐Copolymer Cathode and Hard‐Carbon Anode

“…In the first cycle, two prominent cathodic peaks near 2.3 and 2.1 V are observed in common, attributed to the stepwise reduction of long‐chain polysulfides (S 8 2− , S 6 2− ) and short‐chain polysulfides (S 2 2− , S 2− ), respectively. For 30 wt % DVB (Figure c), the dominance of the cathodic peak current at 2.15 V over that at 2.35 V implies the production of mainly short‐chain polysulfides, similar to elemental S . For 10 wt % DVB (Figure d), similar peak currents at 2.3 and 2.1 V indicate the generation of long‐chain polysulfides together with short‐chain polysulfides .…”

“…)a nd short-chain polysulfides (S 2 2À ,S 2À ), respectively.F or 30 wt %D VB (Figure 1c), the dominance of the cathodic peak current at 2.15 V over that at 2.35 Vi mplies the production of mainly shortchain polysulfides,s imilart oe lemental S. [8,9,21] For 10 wt %D VB (Figure 1d), similarp eak currents at 2.3 and 2.1 Vi ndicate the generation of long-chain polysulfidest ogether with shortchain polysulfides. [9] An additional weak,y et distinct, cathodic peak at 2.18 Vi so bserved justf or 10 wt %D VB (Figure 1d)i n the first cycle, the current of whichd iminishes with cycling.…”

“…This may be due to lower structural rigidity for 30 wt % DVB compared with 10 wt % DVB, and thus a higher degree of polysulfides dissolution into the electrolyte. The reverse process shows an anodic peak at 2.4 V due to oxidation of polysulfides to regenerate sulfur . Whereas the redox processes for 10 wt % DVB (Figure d) are quite reversible throughout three cycles, peak currents for 30 wt % DVB (Figure c) diminish rapidly with cycling, similar to poly(S‐ co ‐DIB) .…”

“…Various efforts to resolve these problems are in progress worldwide. Recently, a new class of sulfur‐copolymer cathode materials, which are obtained by inverse vulcanization of molten sulfur with unsaturated organic diene and diyne comonomers through the formation of C−S bonds, have attracted particular attention due to improved cycling ability compared to elemental sulfur, good processability, and facile synthetic route . Previously, we investigated the redox mechanisms and sulfur‐content‐dependent cycling behavior of sulfur‐copolymer (poly(S‐ co ‐DIB), DIB=1,3‐diisopropenylbenzene) cathodes by electrochemistry and ex situ solid‐state NMR spectroscopy .…”

“…Re-cently,anew class of sulfur-copolymer cathode materials, which are obtainedb yi nverse vulcanization of molten sulfur with unsaturated organic diene and diyne comonomers through the formation of CÀSb onds, have attracted particular attention due to improved cycling ability compared to elemental sulfur,g ood processability,a nd facile synthetic route. [6][7][8][9] Previously,w ei nvestigatedt he redox mechanisms and sulfurcontent-dependentc yclingb ehavior of sulfur-copolymer (poly(S-co-DIB), DIB = 1,3-diisopropenylbenzene) cathodes by electrochemistry and ex situ solid-state NMR spectroscopy. [9] We clarified that the cycling stability of these cathodes originates from the role of organic moieties to anchorp olysulfides to the polymericn etwork during cycling and thus reduced iffusion of polysulfides into the electrolyte.…”