The electrochemical reversibility of Mg in hybrid electrolytes based on mixtures of ionic liquid and glyme based organic solvents was investigated for applications in rechargeable magnesium batteries(RMBs). The electr...The electrochemical reversibility of Mg in hybrid electrolytes based on mixtures of ionic liquid and glyme based organic solvents was investigated for applications in rechargeable magnesium batteries(RMBs). The electrolytes demonstrate reversible reduction and oxidation of Mg only after being pre-treated with the dehydrating agent, magnesium borohydride, Mg[BH_4]_2, highlighting the importance of removing water in Mg based electrolytes. The addition magnesium di[bis(trifluoromethanesulfonyl)imide](Mg[TFSI]_2)(0.3 M) to N-butyl-n-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C4 mpyr][TFSI]/tetraglyme at a mole ratio of 1:2 showed stable CV cycling over almost 300 cycles while scanning electron microscopy(SEM) and X-ray diffraction(XRD) confirmed Mg deposition, showing non-dendritic morphology and a well-aligned growth. Further thermogravimetric analysis(TGA) demonstrated a mass retention of 79% at 250℃ for this electrolyte suggesting that the presence of the ionic liquid increases thermal stability substantially making these hybrid electrolytes compatible for RMBs.展开更多
The polypropylene/glass fiber（PP/GF） composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis（t...The polypropylene/glass fiber（PP/GF） composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis（trifluoromethanesulfonyl）imide（Li-TFSI）, into the PP/GF composites. It was considered that GF could play the role as the pathways for the movements of ions in the ternary composites. In this work, the interactions between Li-TFSI and glass fiber and the effects of such interactions on the physical properties of the composites have been systematically investigated. Three types of glass fibers with different ―OH group concentrations have been prepared in order to compare the interactions between GF and Li-TFSI. It was found that the ―OH group concentrations on the surface of glass fiber have significant effects on interactions between glass fibers and Li-TFSI. Such interactions are crucial for both the antistatic and mechanical performances of the final PP/GF/Li-TFSI composites. The investigation indicated that the GF with high ―OH group concentrations confined the movement of TFSI-, which decreased the antistatic properties of PP/GF/Li-TFSI composites. On the other hand, the GF with low ―OH group concentrations inhibited the absorption of Li-TFSI onto the GF, which also hindered the formation of Li-TFSI conductive pathway. The best antistatic performance of the ternary composites can be achieved at the intermediate ―OH concentrations on the GF.展开更多
Using ab initio molecular dynamics(AIMD)simulations,classical molecular dynamics(CMD)simulations,small-angle X-ray scattering(SAXS),and pulsed-field gradient nuclear magnetic resonance(PFG-NMR),the solvation structure...Using ab initio molecular dynamics(AIMD)simulations,classical molecular dynamics(CMD)simulations,small-angle X-ray scattering(SAXS),and pulsed-field gradient nuclear magnetic resonance(PFG-NMR),the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide(Mg(TFSI)_(2))aqueous electrolyte at 1,2,and 3 m concentrations are investigated.From AIMD and CMD simulations,the first solvation shell of an Mg;ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid.The TFSI^(-)ions prefer to stay in the second solvation shell and beyond.Meanwhile,the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)_(2)aqueous electrolytes have been observed,which is mainly due to the formation of the stable[Mg(H_(2)O_(6))_(2)]^(+)complex,and,as a result,the increased effective Mg ion size.Finally,the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m,suggesting the enhanced correlations between ions in the multivalent electrolytes.This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte,providing insight for rational designs of electrolytes for improved ion transport properties.展开更多
The preparation of binder and carbon-free electrodes is of great interest owing to their higher energy density.In this scope,electrodeposition is a suitable method that can be easily scaled up provided that suitable c...The preparation of binder and carbon-free electrodes is of great interest owing to their higher energy density.In this scope,electrodeposition is a suitable method that can be easily scaled up provided that suitable chemical reactants are used.In this work,we used a highly soluble Sn precursor based on TFSI counter ions dissolved in an[EMIm^(+)][TFSI^(−)]ionic liquid.The use of similar anionic groups in both the Sn precursor and the solvent allowed avoiding impurities typically encountered when using the Sn chloride precursor.The resulting solution was characterized by cyclic voltammetry using either an inert(Mo)or a reactive substrate(Cu).In both cases,the electrodeposition occurred in a diffusion controlled process.In the case of Cu,however,a Cu-Sn alloy that is theη-Cu_(6)Sn_(5)phase was identified.An FIB cross section revealed that Cu and Sn interdiffused and that no epitaxial growth occurred.Prolonging the electrodeposition time favored the formation ofβ-Sn because Cu could no longer diffuse within the deposited structure.This resulted in a mixedβ-Sn/η-Cu_(6)Sn_(5)composite whose proportions depended on the deposition duration time.The deposited samples were directly assembled in lithium coin cells to characterize the capacity and cyclability of the binder and carbon-free electrodes.Increasing the mass of the deposited sample degraded the capacity and reversibility of the system which was explained by a lower ability to accommodate the volume variation occurring during the electrochemical lithiation/delithiation process.展开更多
自2007年奥迪Cross Coupe Quattro概念车在上海车展亮相以来,这款定位奥迪紧凑型SUV的产品就在逐步向我们的生活靠近。SUV的流行很大程度上反映出了近年汽车消费观的变化,而节能环保等问题也使得SUV的体积、排量都向小型化方向发展,这...自2007年奥迪Cross Coupe Quattro概念车在上海车展亮相以来,这款定位奥迪紧凑型SUV的产品就在逐步向我们的生活靠近。SUV的流行很大程度上反映出了近年汽车消费观的变化,而节能环保等问题也使得SUV的体积、排量都向小型化方向发展,这或许是平衡得失最恰当的一种方式,在宝马X1、路虎神行者等豪华入门SUV市场不断扩大的同时,奥迪在集各家之所长后,顺理成章的推出了Cross Coupe Quattro概念车量产版车型奥迪Q3。展开更多
基金support from the Australian Research Council for his Australian Laureate Fellowship
文摘The electrochemical reversibility of Mg in hybrid electrolytes based on mixtures of ionic liquid and glyme based organic solvents was investigated for applications in rechargeable magnesium batteries(RMBs). The electrolytes demonstrate reversible reduction and oxidation of Mg only after being pre-treated with the dehydrating agent, magnesium borohydride, Mg[BH_4]_2, highlighting the importance of removing water in Mg based electrolytes. The addition magnesium di[bis(trifluoromethanesulfonyl)imide](Mg[TFSI]_2)(0.3 M) to N-butyl-n-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C4 mpyr][TFSI]/tetraglyme at a mole ratio of 1:2 showed stable CV cycling over almost 300 cycles while scanning electron microscopy(SEM) and X-ray diffraction(XRD) confirmed Mg deposition, showing non-dendritic morphology and a well-aligned growth. Further thermogravimetric analysis(TGA) demonstrated a mass retention of 79% at 250℃ for this electrolyte suggesting that the presence of the ionic liquid increases thermal stability substantially making these hybrid electrolytes compatible for RMBs.
基金financially supported by the National Natural Science Foundation of China(Nos.21674033 and 51173036)
文摘The polypropylene/glass fiber（PP/GF） composites with excellent antistatic performance and improved mechanical properties have been reported by incorporation of a very small amount of the organic salt, lithium bis（trifluoromethanesulfonyl）imide（Li-TFSI）, into the PP/GF composites. It was considered that GF could play the role as the pathways for the movements of ions in the ternary composites. In this work, the interactions between Li-TFSI and glass fiber and the effects of such interactions on the physical properties of the composites have been systematically investigated. Three types of glass fibers with different ―OH group concentrations have been prepared in order to compare the interactions between GF and Li-TFSI. It was found that the ―OH group concentrations on the surface of glass fiber have significant effects on interactions between glass fibers and Li-TFSI. Such interactions are crucial for both the antistatic and mechanical performances of the final PP/GF/Li-TFSI composites. The investigation indicated that the GF with high ―OH group concentrations confined the movement of TFSI-, which decreased the antistatic properties of PP/GF/Li-TFSI composites. On the other hand, the GF with low ―OH group concentrations inhibited the absorption of Li-TFSI onto the GF, which also hindered the formation of Li-TFSI conductive pathway. The best antistatic performance of the ternary composites can be achieved at the intermediate ―OH concentrations on the GF.
基金supported by the Joint Center for Energy Storage Research(JCESR),a U.S.Department of Energy,Energy Innovation Hub。
文摘Using ab initio molecular dynamics(AIMD)simulations,classical molecular dynamics(CMD)simulations,small-angle X-ray scattering(SAXS),and pulsed-field gradient nuclear magnetic resonance(PFG-NMR),the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide(Mg(TFSI)_(2))aqueous electrolyte at 1,2,and 3 m concentrations are investigated.From AIMD and CMD simulations,the first solvation shell of an Mg;ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid.The TFSI^(-)ions prefer to stay in the second solvation shell and beyond.Meanwhile,the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)_(2)aqueous electrolytes have been observed,which is mainly due to the formation of the stable[Mg(H_(2)O_(6))_(2)]^(+)complex,and,as a result,the increased effective Mg ion size.Finally,the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m,suggesting the enhanced correlations between ions in the multivalent electrolytes.This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte,providing insight for rational designs of electrolytes for improved ion transport properties.
基金the“Agence Nationale de la Recherche(ANR)”in the framework of the“Investissements d’Avenir”with the reference“ANR-11-EQPX-0020”(GENESIS EQUIPEX)for the financial support that allowed the acquisition of the FIB system(HELIOS Nanolab 600 from FEI)for TEM sample preparations.
文摘The preparation of binder and carbon-free electrodes is of great interest owing to their higher energy density.In this scope,electrodeposition is a suitable method that can be easily scaled up provided that suitable chemical reactants are used.In this work,we used a highly soluble Sn precursor based on TFSI counter ions dissolved in an[EMIm^(+)][TFSI^(−)]ionic liquid.The use of similar anionic groups in both the Sn precursor and the solvent allowed avoiding impurities typically encountered when using the Sn chloride precursor.The resulting solution was characterized by cyclic voltammetry using either an inert(Mo)or a reactive substrate(Cu).In both cases,the electrodeposition occurred in a diffusion controlled process.In the case of Cu,however,a Cu-Sn alloy that is theη-Cu_(6)Sn_(5)phase was identified.An FIB cross section revealed that Cu and Sn interdiffused and that no epitaxial growth occurred.Prolonging the electrodeposition time favored the formation ofβ-Sn because Cu could no longer diffuse within the deposited structure.This resulted in a mixedβ-Sn/η-Cu_(6)Sn_(5)composite whose proportions depended on the deposition duration time.The deposited samples were directly assembled in lithium coin cells to characterize the capacity and cyclability of the binder and carbon-free electrodes.Increasing the mass of the deposited sample degraded the capacity and reversibility of the system which was explained by a lower ability to accommodate the volume variation occurring during the electrochemical lithiation/delithiation process.
文摘自2007年奥迪Cross Coupe Quattro概念车在上海车展亮相以来,这款定位奥迪紧凑型SUV的产品就在逐步向我们的生活靠近。SUV的流行很大程度上反映出了近年汽车消费观的变化,而节能环保等问题也使得SUV的体积、排量都向小型化方向发展,这或许是平衡得失最恰当的一种方式,在宝马X1、路虎神行者等豪华入门SUV市场不断扩大的同时,奥迪在集各家之所长后,顺理成章的推出了Cross Coupe Quattro概念车量产版车型奥迪Q3。
