Ethylene oxide(EO) and propylene oxide(PO) random copolyethers were synthesized by the sequential addition of the mixture of ethylene oxide and propylene oxide to propylene glycol (initiator) in the presence of potass...Ethylene oxide(EO) and propylene oxide(PO) random copolyethers were synthesized by the sequential addition of the mixture of ethylene oxide and propylene oxide to propylene glycol (initiator) in the presence of potassium hydroxide(KOH), and characterized with infrared spectrum(FTIR) and nuclear magnetism resonance(NMR). The effects of catalyst concentration, reaction temperature, charging rate and EO/PO mixture ratio on the polymerization reaction were investigated. It was revealed that the optimal reaction condition is the ratio of 2.5∶1 000(KOH mass vs. product mass), at 114.6℃ and pressure below 0.4 MPa. The residual KOH was neutralized by phosphoric acid(H 3PO 4). Then the crude copolyether was refined with adsorbents, and the refined copolyether, which contains less than 0.7 μg/ml K+, was obtained as colorless, viscous liquid.展开更多
Due to its high energy density,lithium-sulfur(Li-S)battery is considered as the most promising candidate for the energy storage systems,but its practical application is hindered by the dissolution of lithium polysulfi...Due to its high energy density,lithium-sulfur(Li-S)battery is considered as the most promising candidate for the energy storage systems,but its practical application is hindered by the dissolution of lithium polysulfides in the electrolyte.In this work,N-bromophthalimide(C8H4NO2Br,NBP),an aromatic molecule with carbophilic,sulfiphilic,lithiophilic,and solvophilic nature,is introduced into active graphene(AG)to fabricate the sulfur composite cathode.The carbophilic NBP is anchored readily on the AG surface viaπ−πstacking interaction.During discharging,the dissolved lithium polysulfide anion(LiS−n)is grafted into the sulfiphilic NBP spontaneously via SN2 substitution reaction to form C8H4NO2SnLi,which brings the dissolved LiS−n back to the AG surface in the composite cathode.Moreover,the lithiophilic and solvophilic nature of NBP improve the wettability of the porous composite cathode,and the electrolyte molecule is easily penetrated into the micro-mesopores of AG to facilitate the diffusion of the electrolyte.Thus,NBP,as a multi-functional compound in Li-S battery,can immobilize LiS−n and enhance the diffusion of the electrolyte.The above features of NBP endow the sulfur composite cathode with improved electrochemical performance in the cycling stability.展开更多
文摘Ethylene oxide(EO) and propylene oxide(PO) random copolyethers were synthesized by the sequential addition of the mixture of ethylene oxide and propylene oxide to propylene glycol (initiator) in the presence of potassium hydroxide(KOH), and characterized with infrared spectrum(FTIR) and nuclear magnetism resonance(NMR). The effects of catalyst concentration, reaction temperature, charging rate and EO/PO mixture ratio on the polymerization reaction were investigated. It was revealed that the optimal reaction condition is the ratio of 2.5∶1 000(KOH mass vs. product mass), at 114.6℃ and pressure below 0.4 MPa. The residual KOH was neutralized by phosphoric acid(H 3PO 4). Then the crude copolyether was refined with adsorbents, and the refined copolyether, which contains less than 0.7 μg/ml K+, was obtained as colorless, viscous liquid.
基金financially supported by the National Natural Science Foundation of China (21573112, 21935006, 21421001 and 21373118)
文摘Due to its high energy density,lithium-sulfur(Li-S)battery is considered as the most promising candidate for the energy storage systems,but its practical application is hindered by the dissolution of lithium polysulfides in the electrolyte.In this work,N-bromophthalimide(C8H4NO2Br,NBP),an aromatic molecule with carbophilic,sulfiphilic,lithiophilic,and solvophilic nature,is introduced into active graphene(AG)to fabricate the sulfur composite cathode.The carbophilic NBP is anchored readily on the AG surface viaπ−πstacking interaction.During discharging,the dissolved lithium polysulfide anion(LiS−n)is grafted into the sulfiphilic NBP spontaneously via SN2 substitution reaction to form C8H4NO2SnLi,which brings the dissolved LiS−n back to the AG surface in the composite cathode.Moreover,the lithiophilic and solvophilic nature of NBP improve the wettability of the porous composite cathode,and the electrolyte molecule is easily penetrated into the micro-mesopores of AG to facilitate the diffusion of the electrolyte.Thus,NBP,as a multi-functional compound in Li-S battery,can immobilize LiS−n and enhance the diffusion of the electrolyte.The above features of NBP endow the sulfur composite cathode with improved electrochemical performance in the cycling stability.
