A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithi...A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithium acetate dihydrate showed highest catalytic activity with 47.9% yield of dimethyl carbonate. This method was a green chemical process.展开更多
Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graph...Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graphite intercalation compounds (AGICs) have been coming into their own in dual-ion batteries [1]. It is imperative to deepen an understanding of anion storage mechanisms in graphite electrode.展开更多
The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical proces...The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical process that is environmentally friendly and produces no poisonous substance. The metal acetate catalysts used for this reaction are discussed in detail. Lithium acetate dihydrate was found to be a novel and efficient catalyst for this reaction. Compared with other metal acetates, lithium acetate dihydrate can attain a maximum catalytic activity at a lower concentration. When the reaction was carried out under the following conditions: the reaction temperature from 230 to 250 ℃, molar ratio of ethylene carbonate(EC) to dimethyl terephthalate(DMT) 3: 1, reaction time 3 h, and a catalyst amount of 0. 4% (molar fraction to DMT), the yield of dimethyl carbonate(DMC) was 79. 1%.展开更多
The efficient hydrogenation of CO_(2)-derived ethylene carbonate(EC)to yield methanol(MeOH)and ethylene glycol(EG)is a key process for indirect conversion of CO_(2)to MeOH.However,a high H_(2)/EC molar ratio during th...The efficient hydrogenation of CO_(2)-derived ethylene carbonate(EC)to yield methanol(MeOH)and ethylene glycol(EG)is a key process for indirect conversion of CO_(2)to MeOH.However,a high H_(2)/EC molar ratio during the hydrogenation process(usually as 180-300)is generally required to achieve good catalytic performance,resulting in high cost and energy consumption for H_(2)circulation in the promising industrial application.Here,we prepared a series of Ni-modified Cu/SiO_(2)catalysts and explored the effects of synthesis methods and Ni contents on catalytic performance under different H_(2)/EC molar ratios.The Cu/SiO_(2)catalyst with 0.2%(mass)Ni loading prepared by co-ammonia evaporation method exhibited above 99%conversion of EC,91%and 98%selectivity to MeOH and EG respectively at H_(2)/EC ratio of 60.And no significant deactivation was observed within 140 h at a lower H_(2)/EC of 40.It is demonstrated that a few of Ni addition could not only promote Cu dispersion and increase surface Cu^(+) species due to the strong interaction between Cu and Ni species,but also form uniformly-dispersed CuNi alloy species and thus enhance the adsorption and dissociation of H_(2).But the excess Ni species would aggregate and segregate to cover partial surface of Cu nanoparticles,leading to a significantly drop of catalytic performance in EC hydrogenation.These insights may provide guidance for further design of catalysts for the ester hydrogenation reactions.展开更多
Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene carbonate(EC),a key step in the indirect conversion of CO_(2) to methanol.However,a high H_(2)/EC molar ratio in feed is...Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene carbonate(EC),a key step in the indirect conversion of CO_(2) to methanol.However,a high H_(2)/EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved.Herein,we fabricated a series of Pt-modulated Cu/SiO_(2) catalysts and investigated their catalytic performance for hydrogenation of EC in a fixed bed reactor.By modulating the Pt amount,the optimal 0.2Pt-Cu/SiO_(2) catalyst exhibited the highest catalytic performance with99%EC conversion,over 98%selectivity to ethylene glycol and 95.8%selectivity to methanol at the H_(2)/EC ratio as low as 60 in feed.In addition,0.2Pt-Cu/SiO_(2) catalyst showed excellent stability for 150 h on stream over different H_(2)/EC ratios of 180-40.It is demonstrated a proper amount of Pt could significantly lower the H_(2)/EC molar ratio,promote the reducibility and dispersion of copper,and also enhance surface density of Cu+species.This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice.Meanwhile,a relatively higher amount of Pt would deteriorate the catalytic activity,which could be due to the surface coverage and aggregation of active species.These findings may enlighten some fundamental insights for further design of Cu-based catalysts for the hydrogenation of carbon–oxygen bonds.展开更多
Ethylene oxide(EO)is an important raw material for producing ethylene carbonate(EC).However,the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption....Ethylene oxide(EO)is an important raw material for producing ethylene carbonate(EC).However,the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption.In this paper,two processes of manufacturing EC from EO mixture gas were studied by process simulation.Two processes for producing EC from EO mixture as raw materials without EO purification,called the OSAC process and the Modified OSAC process,were developed and assessed systematically.Both processes use EC as the absorbent to capture EO,avoiding the separation process of EO from solution.For comparisons,the EC producing process containing EO absorption by water,EO refinement and carbonylation process were also modeled,which was called the ERC process.Three schemes were designed for the EO absorber using EC as absorbent.Compared with the initial absorber scheme,the optimal liquid–vapor ratio is reduced from 1.66 to 1.45(mass).Moreover,the mass distribution analysis for the three processes were carried out in the form of the material chain.It was found that,compared with the ERC process,the energy consumption of the OSAC and the Modified OSAC process is reduced by 56.89%and 30.03%,respectively.This work will provide helpful information for the industrialization of the OSAC process.展开更多
In this study,rice straw(RS) was liquefied by ethylene carbonate(EC) using H_2SO_4 as a catalyst.The effects of various process conditions on the liquefaction characteristics were investigated by FT-IR and residue con...In this study,rice straw(RS) was liquefied by ethylene carbonate(EC) using H_2SO_4 as a catalyst.The effects of various process conditions on the liquefaction characteristics were investigated by FT-IR and residue content analysis.The results show that cellulose and lignin are degraded during the liquefaction process and large amounts of groups are generated.In addition,it is difficult to effectively liquefy RS by using EC alone as the liquefying agent without other additives.Compared to water addition on liquefaction,the residue content can be significantly reduced up to 30% by adding H_2O_2.It has also been proved that the liquor ratio(RS/EC,w/v) of 1∶5 with H_2O_2 as an additive at 145℃ for liquefaction time of 60 min in the presence of H_2SO_4 can accelerate the liquefaction process and high liquefaction yield can be obtained.展开更多
The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % co...The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % conversionand a 98% selectivity at low temperature andunder low pressure, featuring high catalytic activity, goodstability, good adaptability to feedstocks and low productioncost.展开更多
High-purity ethylene carbonate(EC)is widely used as battery electrolyte,polycarbonate monomer,organic intermediate,and so on.An economical and sustainable route to synthesize high-purity ethylene carbonate(EC)via the ...High-purity ethylene carbonate(EC)is widely used as battery electrolyte,polycarbonate monomer,organic intermediate,and so on.An economical and sustainable route to synthesize high-purity ethylene carbonate(EC)via the transesterification of dimethyl carbonate(DMC)with ethylene glycol(EG)is provided in this work.However,this reaction is so fast that the reaction kinetics,which is essential for the industrial design,is hard to get by the traditional measuring method.In this work,an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst.The effects of flow rate,microreactor diameter,catalyst concentration,reaction temperature,and reactant molar ratio were investigated.An activity-based pseudohomogeneous kinetic model,which considered the non-ideal properties of reaction system,was established to describe the transesterification of DMC with EG.Detailed kinetics data were collected in the first 5 min.Using these data,the parameters of the kinetic model were correlated with the maximum average error of 11.19%.Using this kinetic model,the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%,suggesting its satisfactory prediction performance.展开更多
The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional...The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional electrochemical tests and in situ X-ray diffraction measurements. Two kinds of graphite intercalation compounds(GICs) with discrete characteristic intercalated gallery heights(IGHs)(ca. 0.95 and0.75 nm) can be obtained with varying the salt concentration. The effect of graphite type is also addressed.展开更多
High-performance solid polymer electrolyte (SPE) has long been desired for the next-generation high energy density and safe rechargeable lithium batteries. A SPE composed of 80 wt% lithium bis(trifluo-romethanesulf...High-performance solid polymer electrolyte (SPE) has long been desired for the next-generation high energy density and safe rechargeable lithium batteries. A SPE composed of 80 wt% lithium bis(trifluo-romethanesulfonyl)imide (LiTFSI), 20% poly(ethylene carbonate) (PEC) and a polyamide (PA) fiber membrane backbone was prepared by solution-casting method. This solid electrolyte exhibits quite high ionic conductivity and lithium ion transference number (t+), and excellent mechanical strength. The as-prepared solid electrolyte shows good wettability to porous electrodes during cycles, which is beneficial to form ionically conductive phase throughout porous electrodes. All-solid-state LiFePO4lLi cells assembled with the as-prepared solid electrolyte deliver a high initial discharge specific capacity of 125.7 mAh·g^-1 and good cycling stability at 55 ℃ (93.4% retention at 1C after 200 cycles), and superior cycle performance. Outstanding electrochemical performance can be mainly ascribed to the improved ionic conductivity in the entire porous electrodes due to the good wettability of SPE.展开更多
The synthesis of sustainable methanol and ethylene glycol(EG)via hydrogenation of ethylene carbonate(EC)has caught researchers’growing interests on account of the indirect chemical utilization of CO_(2).Core-shell Cu...The synthesis of sustainable methanol and ethylene glycol(EG)via hydrogenation of ethylene carbonate(EC)has caught researchers’growing interests on account of the indirect chemical utilization of CO_(2).Core-shell Cu@GO catalysts with random nanoporous network of graphite oxide(GO)were synthesized via a simple method of ul-trasonic precipitation.Cu@GO catalysts were analyzed systematically by N_(2) physisorption,TGA measurement,XRD,FT-IR,Raman,TEM,SEM,and XPS(XAES).In particular,the mentioned method was confirmed to be effective to fabricate the high dispersity core-shell Cu@GO catalysts through promoting the specific surface area.The as-prepared Cu@GO catalyst was then successfully applied in the hydrogenation of CO_(2)-derived EC to pro-duce methanol and EG.A high TOF of 1526 mg EC g cat^(-1) h^(-1) could be attained in EC hydrogenation at the reaction temperature of 493K.Accordingly,the correlation of catalytic structure and performance disclosed that the synergistic effect between Cu^(+) and Cu^(0) was responsible for achieving high activity of the catalyst.In addition,the reusability of Cu@GO catalyst suggested that graphite oxide shell structure could decrease the aggregation of Cu particles,thus enhance the stability of Cu-based catalysts.DFT calculation results suggested that the involvement of carbon film on Cu was favorable for the stabilization of the active sites.This study is helpful for developing new and stable catalytic system for indirect chemical utilization of CO_(2) to synthesize commodity methanol and EG.展开更多
With the booming development of lithium-ion batteries,safety has become one of the most primary focuses of current researches.Although there are various approaches to enhance the safety of lithiumion batteries,phospha...With the booming development of lithium-ion batteries,safety has become one of the most primary focuses of current researches.Although there are various approaches to enhance the safety of lithiumion batteries,phosphate-based electrolyte holds the greatest potential for practical application due to their non-flammability.Nonetheless,its compatibility issue with the graphite anode remains a significant obstacle to its widespread use.Herein,an effective method is proposed to improve the compatibility of electrolyte with graphite(Gr)anode by rationally adjusting the proportion of lithium salt and solvent components to optimize the Li^(+)solvation structure.By slightly increasing the Li^(+)/triethyl phosphate(TEP)ratio,TEP alone cannot fully occupy the inner solvation sheath and therefore less polar ethylene carbonate(EC)has to be recruited,and the solvation structure gradually changes from Li^(+)–[TEP]_(4)to Li^(+)–[TEP]_(3)[EC]with the coexistence of EC and TEP.Simultaneously,EC molecules in the Li^(+)–[TEP]_(3)[EC]could be preferentially reduced on graphite compared to the TEP molecules,resulting in the formation of a uniform and durable solid-electrolyte interphase(SEI)layer.Benefiting from the optimized phosphate-based electrolyte,the Gr|Li battery exhibits a capacity retention rate of 96.8%after stable cycling at 0.5 C for 470 cycles which shows a longer cycle life than the battery with carbonate electrolyte(cycling at 0.5 C for 450 cycles).Therefore,this work provides the guidance for designing a non-flammable phosphate-based electrolyte for high-safety and long cycling-life lithium-ion batteries.展开更多
Actively tunable acoustic metamaterials have attracted ever increasing attention.However,their tunable frequency range is quite narrow(tens of Hz)even under ultrahigh applied voltage(about 1,000 V).Here,we report a su...Actively tunable acoustic metamaterials have attracted ever increasing attention.However,their tunable frequency range is quite narrow(tens of Hz)even under ultrahigh applied voltage(about 1,000 V).Here,we report a superbroad-band actively tunable acoustic metamaterials with the bandwidth over 400 Hz under a low voltage.In the actively tunable acoustic metamaterials,the acoustic membrane is a laminated nanocomposite consisting of a poly(ethylene terephthalate)(PET)and super-aligned carbon nanotube(CNT)drawn from CN T forest array.The laminated nanocomposite membrane exhibits adjustable acoustic properties,whose modulus can be adjusted by applying external electric field.The maximum frequency bandwidth of PET/CN T nanocomposite membrane reaches 419 Hz when applying an external DC voltage of 60 V.Our actively tunable acoustic metamaterials with superbroad-band and lightweight show very promising foreground in noise reduction applications.展开更多
Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by ...Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D). It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.展开更多
文摘A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithium acetate dihydrate showed highest catalytic activity with 47.9% yield of dimethyl carbonate. This method was a green chemical process.
基金financially supported by the National Natural Science Foundation of China(21975251)。
文摘Graphite is a universal host material for ion intercalation. Li+-graphite intercalation compounds (GICs) have been successfully utilized as the anode material in commercial lithium-ion batteries.Similarly, anion-graphite intercalation compounds (AGICs) have been coming into their own in dual-ion batteries [1]. It is imperative to deepen an understanding of anion storage mechanisms in graphite electrode.
基金the National High Technology Research and Development Program of China(No 2003AA321010)
文摘The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical process that is environmentally friendly and produces no poisonous substance. The metal acetate catalysts used for this reaction are discussed in detail. Lithium acetate dihydrate was found to be a novel and efficient catalyst for this reaction. Compared with other metal acetates, lithium acetate dihydrate can attain a maximum catalytic activity at a lower concentration. When the reaction was carried out under the following conditions: the reaction temperature from 230 to 250 ℃, molar ratio of ethylene carbonate(EC) to dimethyl terephthalate(DMT) 3: 1, reaction time 3 h, and a catalyst amount of 0. 4% (molar fraction to DMT), the yield of dimethyl carbonate(DMC) was 79. 1%.
基金the supports from the National Natural Science Foundation of China(22022811,U21B2096 and 21938008)the National Key Research&Development Program of China(2018YFB0605803)。
文摘The efficient hydrogenation of CO_(2)-derived ethylene carbonate(EC)to yield methanol(MeOH)and ethylene glycol(EG)is a key process for indirect conversion of CO_(2)to MeOH.However,a high H_(2)/EC molar ratio during the hydrogenation process(usually as 180-300)is generally required to achieve good catalytic performance,resulting in high cost and energy consumption for H_(2)circulation in the promising industrial application.Here,we prepared a series of Ni-modified Cu/SiO_(2)catalysts and explored the effects of synthesis methods and Ni contents on catalytic performance under different H_(2)/EC molar ratios.The Cu/SiO_(2)catalyst with 0.2%(mass)Ni loading prepared by co-ammonia evaporation method exhibited above 99%conversion of EC,91%and 98%selectivity to MeOH and EG respectively at H_(2)/EC ratio of 60.And no significant deactivation was observed within 140 h at a lower H_(2)/EC of 40.It is demonstrated that a few of Ni addition could not only promote Cu dispersion and increase surface Cu^(+) species due to the strong interaction between Cu and Ni species,but also form uniformly-dispersed CuNi alloy species and thus enhance the adsorption and dissociation of H_(2).But the excess Ni species would aggregate and segregate to cover partial surface of Cu nanoparticles,leading to a significantly drop of catalytic performance in EC hydrogenation.These insights may provide guidance for further design of catalysts for the ester hydrogenation reactions.
基金supported by the National Natural Science Foun-dation of China(22022811,U21B2096 and 21938008)the National Key Research&Development Program of China(2018YFB0605803).
文摘Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene carbonate(EC),a key step in the indirect conversion of CO_(2) to methanol.However,a high H_(2)/EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved.Herein,we fabricated a series of Pt-modulated Cu/SiO_(2) catalysts and investigated their catalytic performance for hydrogenation of EC in a fixed bed reactor.By modulating the Pt amount,the optimal 0.2Pt-Cu/SiO_(2) catalyst exhibited the highest catalytic performance with99%EC conversion,over 98%selectivity to ethylene glycol and 95.8%selectivity to methanol at the H_(2)/EC ratio as low as 60 in feed.In addition,0.2Pt-Cu/SiO_(2) catalyst showed excellent stability for 150 h on stream over different H_(2)/EC ratios of 180-40.It is demonstrated a proper amount of Pt could significantly lower the H_(2)/EC molar ratio,promote the reducibility and dispersion of copper,and also enhance surface density of Cu+species.This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice.Meanwhile,a relatively higher amount of Pt would deteriorate the catalytic activity,which could be due to the surface coverage and aggregation of active species.These findings may enlighten some fundamental insights for further design of Cu-based catalysts for the hydrogenation of carbon–oxygen bonds.
基金financially supported by the National Key Research and Development Program of China(2018YFB0605802)National Natural Science Foundation of China(No.21978293,U1704251)。
文摘Ethylene oxide(EO)is an important raw material for producing ethylene carbonate(EC).However,the traditional method for the separation of EO from mixture gas by water in the refining process is high energy consumption.In this paper,two processes of manufacturing EC from EO mixture gas were studied by process simulation.Two processes for producing EC from EO mixture as raw materials without EO purification,called the OSAC process and the Modified OSAC process,were developed and assessed systematically.Both processes use EC as the absorbent to capture EO,avoiding the separation process of EO from solution.For comparisons,the EC producing process containing EO absorption by water,EO refinement and carbonylation process were also modeled,which was called the ERC process.Three schemes were designed for the EO absorber using EC as absorbent.Compared with the initial absorber scheme,the optimal liquid–vapor ratio is reduced from 1.66 to 1.45(mass).Moreover,the mass distribution analysis for the three processes were carried out in the form of the material chain.It was found that,compared with the ERC process,the energy consumption of the OSAC and the Modified OSAC process is reduced by 56.89%and 30.03%,respectively.This work will provide helpful information for the industrialization of the OSAC process.
基金supported by the National Natural Science Foundation of China(31270633)State Key Laboratory of Pulp and Paper Engineering(201512)Hangzhou Qianjiang Distinguished Experts Programme of China
文摘In this study,rice straw(RS) was liquefied by ethylene carbonate(EC) using H_2SO_4 as a catalyst.The effects of various process conditions on the liquefaction characteristics were investigated by FT-IR and residue content analysis.The results show that cellulose and lignin are degraded during the liquefaction process and large amounts of groups are generated.In addition,it is difficult to effectively liquefy RS by using EC alone as the liquefying agent without other additives.Compared to water addition on liquefaction,the residue content can be significantly reduced up to 30% by adding H_2O_2.It has also been proved that the liquor ratio(RS/EC,w/v) of 1∶5 with H_2O_2 as an additive at 145℃ for liquefaction time of 60 min in the presence of H_2SO_4 can accelerate the liquefaction process and high liquefaction yield can be obtained.
文摘The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % conversionand a 98% selectivity at low temperature andunder low pressure, featuring high catalytic activity, goodstability, good adaptability to feedstocks and low productioncost.
基金support for this work from the National Natural Science Foundation of China(21706034)the Natural Science Foundation of Fujian Province(2021J01645)the Key Program of Qingyuan Innovation Laboratory(00221004).
文摘High-purity ethylene carbonate(EC)is widely used as battery electrolyte,polycarbonate monomer,organic intermediate,and so on.An economical and sustainable route to synthesize high-purity ethylene carbonate(EC)via the transesterification of dimethyl carbonate(DMC)with ethylene glycol(EG)is provided in this work.However,this reaction is so fast that the reaction kinetics,which is essential for the industrial design,is hard to get by the traditional measuring method.In this work,an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst.The effects of flow rate,microreactor diameter,catalyst concentration,reaction temperature,and reactant molar ratio were investigated.An activity-based pseudohomogeneous kinetic model,which considered the non-ideal properties of reaction system,was established to describe the transesterification of DMC with EG.Detailed kinetics data were collected in the first 5 min.Using these data,the parameters of the kinetic model were correlated with the maximum average error of 11.19%.Using this kinetic model,the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%,suggesting its satisfactory prediction performance.
基金financially supported by National Natural Science Foundation of China (No. 21975251)。
文摘The intercalation behavior of spiro-(1,1)-bipyrrolidinium cation(SBP+) into graphite electrode from spiro-(1,1)-bipyrrolidinium tetrafluoroborate-ethylene carbonate(SBPBF4-EC) solutions is investigated by conventional electrochemical tests and in situ X-ray diffraction measurements. Two kinds of graphite intercalation compounds(GICs) with discrete characteristic intercalated gallery heights(IGHs)(ca. 0.95 and0.75 nm) can be obtained with varying the salt concentration. The effect of graphite type is also addressed.
基金financially supported by the National Natural Scientific Foundation of China(No.51532002)Beijing Natural Science Foundation(No.L172023)the National Basic Research Program of China(No.2015CB932500)
文摘High-performance solid polymer electrolyte (SPE) has long been desired for the next-generation high energy density and safe rechargeable lithium batteries. A SPE composed of 80 wt% lithium bis(trifluo-romethanesulfonyl)imide (LiTFSI), 20% poly(ethylene carbonate) (PEC) and a polyamide (PA) fiber membrane backbone was prepared by solution-casting method. This solid electrolyte exhibits quite high ionic conductivity and lithium ion transference number (t+), and excellent mechanical strength. The as-prepared solid electrolyte shows good wettability to porous electrodes during cycles, which is beneficial to form ionically conductive phase throughout porous electrodes. All-solid-state LiFePO4lLi cells assembled with the as-prepared solid electrolyte deliver a high initial discharge specific capacity of 125.7 mAh·g^-1 and good cycling stability at 55 ℃ (93.4% retention at 1C after 200 cycles), and superior cycle performance. Outstanding electrochemical performance can be mainly ascribed to the improved ionic conductivity in the entire porous electrodes due to the good wettability of SPE.
基金We are grateful to the National Natural Science Foundation of China(21576272)“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA 21030600)+1 种基金Science and Technology Service Network Initiative,Chinese Academy of Sciences(KFJ-STS-QYZD-138)the National Key Research and Development Program of China(2019YFC1906701)for the financial supports.
文摘The synthesis of sustainable methanol and ethylene glycol(EG)via hydrogenation of ethylene carbonate(EC)has caught researchers’growing interests on account of the indirect chemical utilization of CO_(2).Core-shell Cu@GO catalysts with random nanoporous network of graphite oxide(GO)were synthesized via a simple method of ul-trasonic precipitation.Cu@GO catalysts were analyzed systematically by N_(2) physisorption,TGA measurement,XRD,FT-IR,Raman,TEM,SEM,and XPS(XAES).In particular,the mentioned method was confirmed to be effective to fabricate the high dispersity core-shell Cu@GO catalysts through promoting the specific surface area.The as-prepared Cu@GO catalyst was then successfully applied in the hydrogenation of CO_(2)-derived EC to pro-duce methanol and EG.A high TOF of 1526 mg EC g cat^(-1) h^(-1) could be attained in EC hydrogenation at the reaction temperature of 493K.Accordingly,the correlation of catalytic structure and performance disclosed that the synergistic effect between Cu^(+) and Cu^(0) was responsible for achieving high activity of the catalyst.In addition,the reusability of Cu@GO catalyst suggested that graphite oxide shell structure could decrease the aggregation of Cu particles,thus enhance the stability of Cu-based catalysts.DFT calculation results suggested that the involvement of carbon film on Cu was favorable for the stabilization of the active sites.This study is helpful for developing new and stable catalytic system for indirect chemical utilization of CO_(2) to synthesize commodity methanol and EG.
基金the National Natural Science Foundation of China(52034011 and 52101278)the Central South University Research Programme of Advanced Interdisciplinary Studies(2023QYJC005)the Fundamental Research Funds for Central Universities of the Central South University(2022ZZTS0405)。
文摘With the booming development of lithium-ion batteries,safety has become one of the most primary focuses of current researches.Although there are various approaches to enhance the safety of lithiumion batteries,phosphate-based electrolyte holds the greatest potential for practical application due to their non-flammability.Nonetheless,its compatibility issue with the graphite anode remains a significant obstacle to its widespread use.Herein,an effective method is proposed to improve the compatibility of electrolyte with graphite(Gr)anode by rationally adjusting the proportion of lithium salt and solvent components to optimize the Li^(+)solvation structure.By slightly increasing the Li^(+)/triethyl phosphate(TEP)ratio,TEP alone cannot fully occupy the inner solvation sheath and therefore less polar ethylene carbonate(EC)has to be recruited,and the solvation structure gradually changes from Li^(+)–[TEP]_(4)to Li^(+)–[TEP]_(3)[EC]with the coexistence of EC and TEP.Simultaneously,EC molecules in the Li^(+)–[TEP]_(3)[EC]could be preferentially reduced on graphite compared to the TEP molecules,resulting in the formation of a uniform and durable solid-electrolyte interphase(SEI)layer.Benefiting from the optimized phosphate-based electrolyte,the Gr|Li battery exhibits a capacity retention rate of 96.8%after stable cycling at 0.5 C for 470 cycles which shows a longer cycle life than the battery with carbonate electrolyte(cycling at 0.5 C for 450 cycles).Therefore,this work provides the guidance for designing a non-flammable phosphate-based electrolyte for high-safety and long cycling-life lithium-ion batteries.
基金the National Natural Science Foundation of China(NSFC)(Nos.52002201,52008223,51772063)Open Fund of innovation institute for Sustainable Maritime Architecture Research and Technology,Qingdao University of Technology(Nu.2020-035)Shenzhen Science and Technology Program(No.KQTD2016112814303055).
文摘Actively tunable acoustic metamaterials have attracted ever increasing attention.However,their tunable frequency range is quite narrow(tens of Hz)even under ultrahigh applied voltage(about 1,000 V).Here,we report a superbroad-band actively tunable acoustic metamaterials with the bandwidth over 400 Hz under a low voltage.In the actively tunable acoustic metamaterials,the acoustic membrane is a laminated nanocomposite consisting of a poly(ethylene terephthalate)(PET)and super-aligned carbon nanotube(CNT)drawn from CN T forest array.The laminated nanocomposite membrane exhibits adjustable acoustic properties,whose modulus can be adjusted by applying external electric field.The maximum frequency bandwidth of PET/CN T nanocomposite membrane reaches 419 Hz when applying an external DC voltage of 60 V.Our actively tunable acoustic metamaterials with superbroad-band and lightweight show very promising foreground in noise reduction applications.
基金financially supported by the Ministry of Science and Technology of China(No.2012CB933802)the Fundamental Research Funds for Central Universities
文摘Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate) (PEOC) macromonomer (PEOCA) were synthesized, and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D). It is shown that the polymeric surface exhibits degradation in seawater depending on the content of the side chains. Field tests in seawater show that the surface constructed by the copolymer can effectively inhibit marine biofouling because it can be self-renewed due to degradation of the copolymer.