Sulfonated polyether ether ketone (SPEEK) with variou s degree of sulfonation (DS) were synthesized by reaction of PEEK with sulfo nic acid as sulfonating agent and solvent.Their proton conductivity and methanol pe rm...Sulfonated polyether ether ketone (SPEEK) with variou s degree of sulfonation (DS) were synthesized by reaction of PEEK with sulfo nic acid as sulfonating agent and solvent.Their proton conductivity and methanol pe rmeability as a function of the degree of sulfonation were investigated.For 46 .71% DS,proton conductivity was 1.68×10 -2S/cm at 80℃ and 4.25×10 -2S/cm at 100℃,which is closed to or superior to that of Nafion 115 me mbrane at the same conditions.Methanol permeability of SPEEK was considerable s maller than that of Nafion 115 membrane.Because of their high conductivity and low methanol permeability,SPEEK membranes appear to be excellent candidate for use in DMFC applications.展开更多
A novel inorganic-organic composite membrane based on sulfonated polyether ether ketone(SPEEK) with embedded phosphotungstic acid(PWA) for direct methanol fuel cells(DMFC) was prepared. IR spectra results indicate tha...A novel inorganic-organic composite membrane based on sulfonated polyether ether ketone(SPEEK) with embedded phosphotungstic acid(PWA) for direct methanol fuel cells(DMFC) was prepared. IR spectra results indicate that PWA was kept in SPEEK matrix as the Keggin structure. From SEM micrograph, it could be found that the solid PWA were well mixed with SPEEK matrix and showed no agglomeration in the membrane. Proton conductivity of the PWA/SPEEK composite membrane is higher than that of pure SPEEK membrane, and is similar or superior to that of Nafion ○R 115 membrane in the temperature range 80—110 ℃. Methanol permeability of the PWA/SPEEK membrane was considerably smaller than that of Nafion ○R 115 membrane. Because of its high conductivity and low methanol permeability, the PWA/SPEEK membrane seems to be an excellent candidate for DMFC applications.展开更多
In order to solve the methanol crossover problem caused by the poor alcohol rejecting ability of the Nafion TM membranes currently used in direct methanol fuel cell (DMFC),polyvinylidene fluoride(PVDF)was blended with...In order to solve the methanol crossover problem caused by the poor alcohol rejecting ability of the Nafion TM membranes currently used in direct methanol fuel cell (DMFC),polyvinylidene fluoride(PVDF)was blended with Nafion material to prepare a new type of membrane for DMFC and its ionic conductivity and the methanol permeability was investigated.PVDF was used here to regulate the ratio between hydrophilic group and the hydrophobic group exist in the blend membranes according to the hydrophilic hydrophobic balance theory proposed in pervaporation.The adding of PVDF lead to a great improvement of the membrane’s MeOH rejection.When PVDF content was increased from 25% to 75%,the MeOH permeability was reduced from～10 -7 to ～10 -9 cm 2/s,1 to 3 orders of magnitude lower than that of Nafion117.The membrane conductivity decreased,although remaining at high value(～10 -4 S/cm),with the increase of PVDF content.Compared with the Nafion117 membrane,the PVDF Nafion blend membrane with only 25% of Nafion showed an improvement in performance by about 40 times,if the ratio( σ/P ) was adopted to characterize the performance of a membrane for DMFC.Percolation theory,cocontinuous morphology features and phase transition model were applied to explain the behavior of membrane conduction.展开更多
Sulfonated phenolphthalein poly(ether sulfone) (SPES C) with various sulfonation degree were synthesized by reaction of PES C with sulfonic acid as sulfonating agent and solvent.Their proton conductivity and methanol ...Sulfonated phenolphthalein poly(ether sulfone) (SPES C) with various sulfonation degree were synthesized by reaction of PES C with sulfonic acid as sulfonating agent and solvent.Their proton conductivity and methanol permeability as a function of the degree of sulfonation were investigated.For 70 21% degree of sulfonation,proton conductivity was 3 45×10 -2 S/cm at 100℃,which is closed to or superior to that of Nafion 115 membrane at the same conditions (4 19×10 -2 S/cm).Methanol permeability of SPES C was considerable smaller than that of Nafion 115 membrane.Because of their high conductivity and low methanol permeability,SPES C membranes appear to be excellent candidate for use in DMFC applications.展开更多
A Nafion 117 complex membrane with low Pd content was prepared. It was found that at room temperature the diffusivity of methanol through this membrane was reduced to one fifth of that through bare Nafion 117 membrane...A Nafion 117 complex membrane with low Pd content was prepared. It was found that at room temperature the diffusivity of methanol through this membrane was reduced to one fifth of that through bare Nafion 117 membrane . The proton conductivity of the modified membrane was also increased, significantly improving the discharge performance of the direct methanol fuel cell(DMFC).展开更多
文摘Sulfonated polyether ether ketone (SPEEK) with variou s degree of sulfonation (DS) were synthesized by reaction of PEEK with sulfo nic acid as sulfonating agent and solvent.Their proton conductivity and methanol pe rmeability as a function of the degree of sulfonation were investigated.For 46 .71% DS,proton conductivity was 1.68×10 -2S/cm at 80℃ and 4.25×10 -2S/cm at 100℃,which is closed to or superior to that of Nafion 115 me mbrane at the same conditions.Methanol permeability of SPEEK was considerable s maller than that of Nafion 115 membrane.Because of their high conductivity and low methanol permeability,SPEEK membranes appear to be excellent candidate for use in DMFC applications.
文摘A novel inorganic-organic composite membrane based on sulfonated polyether ether ketone(SPEEK) with embedded phosphotungstic acid(PWA) for direct methanol fuel cells(DMFC) was prepared. IR spectra results indicate that PWA was kept in SPEEK matrix as the Keggin structure. From SEM micrograph, it could be found that the solid PWA were well mixed with SPEEK matrix and showed no agglomeration in the membrane. Proton conductivity of the PWA/SPEEK composite membrane is higher than that of pure SPEEK membrane, and is similar or superior to that of Nafion ○R 115 membrane in the temperature range 80—110 ℃. Methanol permeability of the PWA/SPEEK membrane was considerably smaller than that of Nafion ○R 115 membrane. Because of its high conductivity and low methanol permeability, the PWA/SPEEK membrane seems to be an excellent candidate for DMFC applications.
文摘In order to solve the methanol crossover problem caused by the poor alcohol rejecting ability of the Nafion TM membranes currently used in direct methanol fuel cell (DMFC),polyvinylidene fluoride(PVDF)was blended with Nafion material to prepare a new type of membrane for DMFC and its ionic conductivity and the methanol permeability was investigated.PVDF was used here to regulate the ratio between hydrophilic group and the hydrophobic group exist in the blend membranes according to the hydrophilic hydrophobic balance theory proposed in pervaporation.The adding of PVDF lead to a great improvement of the membrane’s MeOH rejection.When PVDF content was increased from 25% to 75%,the MeOH permeability was reduced from～10 -7 to ～10 -9 cm 2/s,1 to 3 orders of magnitude lower than that of Nafion117.The membrane conductivity decreased,although remaining at high value(～10 -4 S/cm),with the increase of PVDF content.Compared with the Nafion117 membrane,the PVDF Nafion blend membrane with only 25% of Nafion showed an improvement in performance by about 40 times,if the ratio( σ/P ) was adopted to characterize the performance of a membrane for DMFC.Percolation theory,cocontinuous morphology features and phase transition model were applied to explain the behavior of membrane conduction.
文摘Sulfonated phenolphthalein poly(ether sulfone) (SPES C) with various sulfonation degree were synthesized by reaction of PES C with sulfonic acid as sulfonating agent and solvent.Their proton conductivity and methanol permeability as a function of the degree of sulfonation were investigated.For 70 21% degree of sulfonation,proton conductivity was 3 45×10 -2 S/cm at 100℃,which is closed to or superior to that of Nafion 115 membrane at the same conditions (4 19×10 -2 S/cm).Methanol permeability of SPES C was considerable smaller than that of Nafion 115 membrane.Because of their high conductivity and low methanol permeability,SPES C membranes appear to be excellent candidate for use in DMFC applications.
文摘A Nafion 117 complex membrane with low Pd content was prepared. It was found that at room temperature the diffusivity of methanol through this membrane was reduced to one fifth of that through bare Nafion 117 membrane . The proton conductivity of the modified membrane was also increased, significantly improving the discharge performance of the direct methanol fuel cell(DMFC).
