The mechanical relaxation time of a two-component epoxy network-LiClO_4 system as a polymer electrolyte was investigated. The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl eth...The mechanical relaxation time of a two-component epoxy network-LiClO_4 system as a polymer electrolyte was investigated. The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG), wherein LiCIO_4 was incorporated and acts as both the ionic carrier and the curing catalyst. As the relaxation time is informative to the segmental mobility, which is known to be essential for ionic conductivity, the average relaxation times of the specimens were determined through master curve construction. Experimental results showed that the salt concentration, molecular weight of PEG in DGEPEG and DGEPEG/TGEG ratio have profound effect on the relaxation time of the specimen. Among these factors , the former reinforces the network chains, leading to lengthen the relaxation time, whereas the latter two are in favour of the chain flexibility and show an opposite effect. The findings was rationalized in terms of the free volume concept.展开更多
Through orthogonal experiment, a new type of LiClO4-LiNO3-LiBr eutectic salt with optimum mole ratio of n（LiClO4）∶n（LiNO3）∶n（LiBr）=1.6∶3.8∶1.0 was prepared. The poly（lithium acrylate-acrylonitrile）/LiClO4-...Through orthogonal experiment, a new type of LiClO4-LiNO3-LiBr eutectic salt with optimum mole ratio of n（LiClO4）∶n（LiNO3）∶n（LiBr）=1.6∶3.8∶1.0 was prepared. The poly（lithium acrylate-acrylonitrile）/LiClO4-LiNO3-LiBr solid polymer electrolytes were prepared with poly（lithium acrylate-acrylonitrile） and （LiClO4-LiNO3-LiBr） eutectic salts. The effect of LiClO4-LiNO3-LiBr eutectic salts content on the conductivity of solid polymer electrolytes was studied by alternating current impedance method, and the structures of eutectic salts and solid polymer electrolytes were characterized by differential thermal analysis, infrared spectroscopy and X-ray diffractometry. The results show that the room temperature conductivity of LiClO4-LiNO3-LiBr eutectic salts reaches (3.11×10-4 S·cm-1.) The poly（lithium acrylate-acrylonitrile）/LiClO4-LiNO3-LiBr solid polymer electrolytes possess the highest room temperature conductivity at 70% LiClO4-LiNO3-LiBr eutectic salts content, and exhibit lower glass transition temperature of 75 ℃ compared with that of poly（lithium acrylate-acrylonitrile） of 105 ℃. A complex may be formed in the solid polymer electrolytes from the differential thermal analysis and infrared spectroscopy analysis. X-ray diffraction results show that the poly（lithium acrylate-acrylonitrile） can suppress the crystallization of eutectic salts in this system.展开更多
Polymeric solid electrolyte system composed of triglycidyl ether of glycerol (TGEG), diglycidyl ether of polyethylene glycol (DGEPEG)and LiClO_4 salt were synthesized. In this' system the electrolyte has a pecular...Polymeric solid electrolyte system composed of triglycidyl ether of glycerol (TGEG), diglycidyl ether of polyethylene glycol (DGEPEG)and LiClO_4 salt were synthesized. In this' system the electrolyte has a pecularity that not merely can the LiClO_4 provide ionic carriers, but also catalyze the crosslinking reaction without adding an usual curing agent. The effect of salt content and degree of crosslinking on the viscoelasticity and ionic conductivity were studied. Both WLF and VTF equations were used to treat the experimental data in order to elucidate the mechanism of ionic conduction. It was found that the ionic conductivity of the system is carded out through the segmental motion mechanism. However, the data must be treated with care. For example, in evaluating WLF parameters, the contribution concerned with ionic carrier generation with temperature to the conductivity must be differentiated from that concerned with segmental motion. Besides, the temperature range suitable to WLF equation must also be considered. For VTF equation, it might be inapplicable ff the temperature is too low and close to the glass transition temperature of the specimen. Further study is needed in order to have a quantitative information on the limitation of these equations.展开更多
基金The project supported by the National Natural Science Foundation of China
文摘The mechanical relaxation time of a two-component epoxy network-LiClO_4 system as a polymer electrolyte was investigated. The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG), wherein LiCIO_4 was incorporated and acts as both the ionic carrier and the curing catalyst. As the relaxation time is informative to the segmental mobility, which is known to be essential for ionic conductivity, the average relaxation times of the specimens were determined through master curve construction. Experimental results showed that the salt concentration, molecular weight of PEG in DGEPEG and DGEPEG/TGEG ratio have profound effect on the relaxation time of the specimen. Among these factors , the former reinforces the network chains, leading to lengthen the relaxation time, whereas the latter two are in favour of the chain flexibility and show an opposite effect. The findings was rationalized in terms of the free volume concept.
文摘Through orthogonal experiment, a new type of LiClO4-LiNO3-LiBr eutectic salt with optimum mole ratio of n（LiClO4）∶n（LiNO3）∶n（LiBr）=1.6∶3.8∶1.0 was prepared. The poly（lithium acrylate-acrylonitrile）/LiClO4-LiNO3-LiBr solid polymer electrolytes were prepared with poly（lithium acrylate-acrylonitrile） and （LiClO4-LiNO3-LiBr） eutectic salts. The effect of LiClO4-LiNO3-LiBr eutectic salts content on the conductivity of solid polymer electrolytes was studied by alternating current impedance method, and the structures of eutectic salts and solid polymer electrolytes were characterized by differential thermal analysis, infrared spectroscopy and X-ray diffractometry. The results show that the room temperature conductivity of LiClO4-LiNO3-LiBr eutectic salts reaches (3.11×10-4 S·cm-1.) The poly（lithium acrylate-acrylonitrile）/LiClO4-LiNO3-LiBr solid polymer electrolytes possess the highest room temperature conductivity at 70% LiClO4-LiNO3-LiBr eutectic salts content, and exhibit lower glass transition temperature of 75 ℃ compared with that of poly（lithium acrylate-acrylonitrile） of 105 ℃. A complex may be formed in the solid polymer electrolytes from the differential thermal analysis and infrared spectroscopy analysis. X-ray diffraction results show that the poly（lithium acrylate-acrylonitrile） can suppress the crystallization of eutectic salts in this system.
基金The project supported by National Natural Science Foundation of China.
文摘Polymeric solid electrolyte system composed of triglycidyl ether of glycerol (TGEG), diglycidyl ether of polyethylene glycol (DGEPEG)and LiClO_4 salt were synthesized. In this' system the electrolyte has a pecularity that not merely can the LiClO_4 provide ionic carriers, but also catalyze the crosslinking reaction without adding an usual curing agent. The effect of salt content and degree of crosslinking on the viscoelasticity and ionic conductivity were studied. Both WLF and VTF equations were used to treat the experimental data in order to elucidate the mechanism of ionic conduction. It was found that the ionic conductivity of the system is carded out through the segmental motion mechanism. However, the data must be treated with care. For example, in evaluating WLF parameters, the contribution concerned with ionic carrier generation with temperature to the conductivity must be differentiated from that concerned with segmental motion. Besides, the temperature range suitable to WLF equation must also be considered. For VTF equation, it might be inapplicable ff the temperature is too low and close to the glass transition temperature of the specimen. Further study is needed in order to have a quantitative information on the limitation of these equations.
