聚合物纳米复合电解质(PEO)8-ZnO-LiClO4微结构及电导率研究

以聚氧化乙烯(PEO)为基质,成功制备出纳米ZnO掺杂的(PEO)₈-ZnO-LiClO₄离子导电聚合物电解质,并利用多种实验技术,包括扫描电子显微镜、X射线衍射(XRD)、傅里叶变换红外光谱和正电子湮没寿命谱(PALS),系统地研究了纳米ZnO与基质间相互作用及其对聚合物链段运动、纳米尺度自由体积、离子输运和复合电解质电导率的影响.实验结果发现,纳米ZnO的掺杂使聚合物电解质的离子电导率得到了大幅度提高,当ZnO与PEO质量比为6%时达到最大,(PEO)₈-ZnO-LiClO₄的电导率为1.82×10^-4 S ·cm^-1,比(PEO)₈-LiClO₄的电导率(6.58×10^-5 S ·cm^-1)提高了大约一个数量级.XRD结果显示,纳米ZnO的加入降低了PEO的结晶性,增加了锂离子传输的非晶相,从而提高了电导率.离散PALS测量结果表明,随着纳米ZnO的加入,复合电解质的自由体积、浓度和相对自由体积分数f_r均增加.连续PALS分析揭示了自由体积的分布由一个峰劈裂成两个峰,表明纳米ZnO的掺杂对聚合物的微结构有很大影响.基于实验测量的f_r和离子电导率,研究了离子导电机理.研究发现, f_r与电导率之间存在一个直接关系,即f_r越大,越有利于锂离子的传输,导致电导率越大.这个结果支持聚合物电解质导电的自由体积理论. 关键词： 正电子湮没寿命谱 聚合物纳米复合电解质 离子电导率 自由体积     

用于染料敏化太阳能电池的聚醚型聚氨酯凝胶电解质的研究

以聚乙二醇(PEG)和异氰酸酯为单体,添加由1,4-丁内酯溶解(C4H9)4NI/I2配制的液态电解质,形成一系列的聚醚型聚氨酯凝胶电解质。通过动态机械热分析(DMTA)、傅里叶红外光谱仪(FTIR)、差示扫描量热仪(DSC)、X射线衍射(XRD)等方法对聚氨酯凝胶电解质结构进行表征,测试结果表明此类电解质具有良好的热稳定性和非晶相结构。同时,研究了PEG分子量、异氰酸酯单体的改变对聚氨酯凝胶电解质电导率的影响,发现PEG分子量的增大使聚氨酯凝胶电解质的电导率先增加后降低,当PEG分子量为10000时,所合成凝胶电解质的电导率达到最大,为6.13mS/cm,而异氰酸酯单体的改变对电解质的电导率影响不大。扫描电子显微镜(SEM)测试结果表明这可能与聚氨酯中形成的不同网状结构有关。在100mW/cm2的入射光强下,不同分子量PEG制备的聚氨酯凝胶电解质组装的染料敏化太阳能电池(DSSCs)的光电性能不同,其中PEG分子量为10000合成的聚氨酯凝胶电解质组装的电池的光电转化效率最高,为4.29%。     

无锂助熔剂B_2O_3对Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3固体电解质离子电导率的影响

采用固相法制备锂离子电池用固体电解质磷酸钛锂铝Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3(LATP),研究了不同烧结温度以及助熔剂对LATP固体电解质离子电导率的影响.采用X射线衍射、能谱分析、扫描电镜和交流阻抗等方法,研究样品的结构特征、元素含量、形貌特征以及离子导电性能.结果表明,在900?C烧结可以获得结构致密、离子电导率较高的纯相LATP陶瓷固体电解质.与添加助熔剂Li BO2的样品进行对比实验发现,采用B_2O_3代替LiBO_2作为助熔剂也可以提高烧结样品的离子电导率,并且电解质的离子电导率随助熔剂添加量的增大,先增大后减小,其中添加质量百分比为2%的B_2O_3的样品具有最高的室温离子电导率,为1.61×10~(-3)S/cm.     

SrCe0.95 Yb0.05 O3-α的制备及其质子导电特性

利用固相反应法制备出固态质子导体SrCe0 .95Yb0 .0 5O3 -α,并使用X射线衍射分析法及低频阻抗测量法对其电子结构和导电特性进行了研究 .X射线分析结果表明 ,该物质为钙钛矿晶体结构 ,具有p型电子空穴和氧离子空穴 .在低温下主要为电子导电 ,且电子导电率随温度的升高而增大 .在含氢气环境中 ,当温度高于 5 5 0K时 ,SrCe0 .95Yb0 .0 5O3 -α具有明显的质子导电性 ,随着温度的升高 ,质子导电性增强 .当温度高于 80 0K时 ,质子是导体中的主要载流子 ,质子电导率可达 4 .5mS/cm .     

用SAXS和XRD方法研究TiO2纳米颗粒微观结构

用溶胶-凝胶方法制备了TiO₂纳米样品，并对该样品在300℃到800℃温度区域进行了退火处理.应用同步辐射X射线粉末衍射(XRD)方法研究了经不同热处理温度的TiO₂纳米颗粒的结构相变.应用同步辐射小角X射线散射(SAXS)方法研究了TiO₂纳米颗粒的表面分形与界面特性.得到纳米颗粒粒度与退火温度的变化规律，讨论了表面界面特征与相变的关系. 关键词： X射线小角散射 X射线衍射 2纳米颗粒')" href="#">TiO₂纳米颗粒     

纯六方相氮化铝泡沫材料的合成

在15 mL的不锈钢反应釜中，利用无水三氯化铝与叠氮化钠在无溶剂的条件下直接反应，合成出了六方结构氮化铝泡沫材料，反应温度650 ℃，反应时间3 h.扫描电子显微镜测试结果显示，该试样呈现泡沫状外貌特征.X射线衍射结果表明该试样为六方结构.不同温度条件下的吸收谱表明在202 nm附近存在尖锐的吸收峰.红外吸收谱中存在1381 cm^-1和730 cm^-1两个吸收峰.同时，提出了六方结构氮化铝泡沫材料的合成机理. 关键词： 六方氮化铝泡沫材料 合成机理 X射线衍射     

K2NiF4型Sr2CrO4的磁电性质研究

以SrO和CrO₂为原料, 在高温高压的条件下直接反应生成纯相的K₂NiF₄结构的Sr₂CrO₄多晶样品. 结构用粉末X射线衍射及GSAS精修表征. 磁化率测试显示样品存在一个弱的反铁磁相变, 奈尔温度为T_N=95 K. 在奈尔温度以上, 磁化率随温度的变化遵循居里-外斯定律. 对样品进行了电阻测试, 结果显示了样品的绝缘特性.     

Ca位置换Fe的氧化物Ca1-xFexMnO3(x=0-0.12)的制备及电输运性能

采用柠檬酸溶胶凝胶结合陶瓷烧结工艺制备了Ca位置换Fe的Ca_1-xFe_xMnO₃(x=0-0.12)氧化物粉末及块体试样,通过X射线衍射及电参数测试分析了所得试样.实验结果表明:在实验范围内,所有试样呈单一物相,Ca位置换Fe之后随置换量的增加,CaMnO₃的晶胞逐渐变小,晶粒长大受到抑制.测试温度范围内所有试样均呈半导体输运特性,电输运机制未发生变化;当x在0- 关键词： 3')" href="#">CaMnO₃ Fe置换 电输运     

Fe掺杂量对双层复合结构BaTi1-zFezO3+δ-Tb1-xDyxFe2-y中磁电耦合的影响

采用溶胶凝胶方法制备了Fe掺杂钛酸钡多晶系列陶瓷BaTi_1-zFe_zO_3+δ(0.005≤z≤0.02) (BTFO).X射线衍射实验显示，所制备的BTFO的结构仍然为四方相钙钛矿.差热分析表明，该BTFO样品的铁电-顺电转变温度及相变潜热随掺杂量z的增加而下降.将该BTFO极化后与Tb_1-xDy_xF 关键词： 磁电耦合 掺杂效应 掺杂钛酸钡     

Pb(Zr,Sn,Ti)O3反铁电陶瓷的低温相变扩散与极化弛豫

用弱场介电温谱、热释电流谱、强场电滞回线和变温X射线衍射谱研究了微量La掺杂Pb(Zr,Sn,Ti)O₃(PZST)反铁电(AFEt)陶瓷在-100—180℃温区内的结构与电学特性.弱场介电温谱显示,AFEt陶瓷在低温段(-100—50℃)呈现介电频率弥散(0.1—100kHz)和扩散型相变的特征,而变温X射线衍射谱却表明材料在这一温区内保持四方相结构;低温下经强场作用后,AFEt被诱导为亚稳三方铁电态,介电频率弥散消失.基于多元复杂化合物的组分起伏理论,讨论了PZST AFEt陶瓷 关键词： Pb(Zr Sn 3反铁电陶瓷')" href="#">Ti)O₃反铁电陶瓷 反铁电弛豫 相变 变温X射线衍射     

Effects of gamma radiation treatment and plasticizer on alkaline solid polymer electrolytes

Alkaline solid polymer electrolyte films have been prepared by the solvent-casting method. Gamma radiation treatment and propylene carbonate plastisizer were used to improve the ionic conductivity of the electrolytes at ambient temperature. The structure of the irradiated electrolytes changes from semi-crystalline to amorphous, indicating that the crosslinking of the polymer has been achieved at a dose of 200 kGy. The ionic conductivity at room temperature of PVA/KOH blend increases from 10⁻⁷ to 10⁻³ Scm⁻¹ after the PVA crosslinking and when the plasticizer concentration was increased from 20 to 30%. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.     

New polymer electrolyte based on (PVA–PAN) blend for Li-ion battery applications

A polymer blend electrolyte based on polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) was prepared by a simple solvent casting technique in different compositions. The ionic conductivity of polymer blend electrolytes was investigated by varying the PAN content in the PVA matrix. The ionic conductivity of polymer blend electrolyte increased with the increase of PAN content. The effect of lithium salt concentrations was also studied for the polymer blend electrolyte of high ionic conductivity system. A maximum ionic conductivity of 3.76×10⁻³ S/cm was obtained in 3 M LiClO₄ electrolyte solution. The effect of ionic conductivity of polymer blend electrolyte was measured by varying the temperature ranging from 298 to 353 K. Linear sweep voltammetry and DC polarization studies were carried out to find out the stability and lithium transference number of the polymer blend electrolyte. Finally, a prototype cell was assembled with graphite as anode, LiMn₂O₄ as cathode, and polymer blend electrolyte as the electrolyte as well as separator, which showed good compatibility and electrochemical stability up to 4.7 V.     

Conductivity studies of plasticized anhydrous PEO-KOH alkaline solid polymer electrolyte

Polyethylene oxide (PEO)–potassium hydroxide (KOH)-based alkaline solid polymer electrolyte films have been prepared by using methanol as solvent. The highest room temperature ionic conductivity of (2.1 ± 0.5) × 10⁻⁸ S cm⁻¹ was achieved for the composition of 70 wt% PEO:30 wt% KOH. The addition of plasticizer, ethylene carbonate, propylene carbonate, or polyethylene glycol to the highest conductivity of PEO–KOH system helps to increase the ambient ionic conductivity to the order of 10⁻⁶–10⁻⁴ S cm⁻¹. The log σ vs 1/T plot of PEO–KOH showed a small conductivity decrease at 50–60 °C range. The small decrease and the hysteresis that occur during the heating–cooling cycle was overcome by the presence of the plasticizer. X-ray diffraction observation supports the conductivity results.     

Effect of nano-dispersed silica on the ion-conducting behavior of PMMA-based polymer gel electrolytes containing LiPF<Subscript>6</Subscript>

Nano-sized silica poly(methylmethacrylate)-based gel electrolyte containing lithium hexafluorophosphate (LiPF₆) was synthesized by using different binary solvent mixture (propylene carbonate(PC) and dimethylformamide (DMF) in different volume ratio). Role of DMF in PC: Higher DMF content in PC-based electrolyte shows higher ionic conductivity at all polymer content and at wide temperature regions (10-70 °C). A small increment in ionic conductivity at lower content of polymer in liquid/gel electrolyte was observed and having maximum conductivity of 13.12 mS/cm at 25 °C. Stability (mechanically and electrically), viscosity and ionic conductivity of gel electrolytes were improved with the addition of nano-sized silica at ambient temperature. Ionic conductivity of nano-sized silica-based gel electrolyte does not change much over 5^o–70 °C temperature range and is factor-wise only which make indispensable in different electrochemical devices. Also polymer gel electrolyte membranes as such and with dispersed silica nano-particles were characterized through scanning electron microscope to study the morphology of gel matrix.     

Solid polymeric electrolyte of PVC–ENR–LiClO<Subscript>4</Subscript>

The ionic conductivity of PVC–ENR–LiClO₄ (PVC, polyvinyl chloride; ENR, epoxidized natural rubber) as a function of LiClO₄ concentration, ENR concentration, temperature, and radiation dose of electron beam cross-linking has been studied. The electrolyte samples were prepared by solution casting technique. Their ionic conductivities were measured using the impedance spectroscopy technique. It was observed that the relationship between the concentration of salt, as well as temperature, and conductivity were linear. The electrolyte conductivity increases with ENR concentration. This relationship was discussed using the number of charge carrier theory. The conductivity–temperature behaviour of the electrolyte is Arrhenian. The conductivity also varies with the radiation dose of the electron beam cross-linking. The highest room temperature conductivity of the electrolyte of 8.5 × 10⁻⁷ S/cm was obtained at 30% by weight of LiClO₄. The activation energy, E _a and pre-exponential factor, σ _o, are 1.4 × 10⁻² eV and 1.5 × 10⁻¹¹ S/cm, respectively.     

The effect of composition,electron irradiation and quenching on ionic conductivity in a new solid polymer electrolyte: (PEG)<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>NH<Subscript>4</Subscript>I

We have prepared, characterized and investigated a new PEG-2000 based solid polymer electrolyte (PEG) _x NH₄I. Ionic conductivity measurements have been made as a function of salt concentration as well as temperature in the range 265–330 K. Selected compositions of the electrolyte were exposed to a beam of 8 MeV electrons to an accumulated dose of 10 kGy to study the effect on ionic conductivity. The electrolyte samples were also quenched at liquid nitrogen temperature and conductivity measurements were made. The ionic conductivity at room temperature exhibits a characteristic double peak for the composition x = 20 and 70. Both electron beam irradiation and quenching at low temperature have resulted in an increase in conductivity by 1–2 orders of magnitude. The enhancement of conductivity upon irradiation and quenching is interpreted as due to an increase in amorphous region and decrease in crystallinity of the electrolyte. DSC and proton NMR measurements also support this conclusion.      

固体电解质Rb4Cu16I7Cl13制备及离子导电性研究

液态固体电解质材料的离子电导率低,安全性问题在一定程度上限制了其发展与应用,而固体电解质材料在室温下具有很好的稳定性和高的离子电导率值,具有较好的应用前景.本文采用机械化学球磨法制备固体电解质Rb₄Cu₁₆I₇Cl₁₃粉末,探索制备工艺和球磨参数,对其晶体结构进行解析、观察粉体微观结构、通过交流阻抗谱及等效电路分析得到了离子电导率与活化能、并详细探讨其离子传导性能与晶体结构的关系以及化学成分稳定性进行研究.实验结果表明,在480 rpm转速下球磨6 h时可得到纯的固体电解质Rb₄Cu₁₆I₇Cl₁₃物相.粉体晶粒尺寸分布均匀,均在20 nm-400 nm之间,室温下固体电解质Rb₄Cu₁₆I₇Cl₁₃离子电导率可达到0.213 S/cm且活化能为0.087(9)eV.在真空干燥条件下存放5天和12天后观察了微观形貌和化学稳定性...     

Structural and ionic conductivity of PEO blend PEG solid polymer electrolyte

Structural and ionic conductivity of PEO blend PEG with KI solid polymer electrolyte system is presented. The polymer PEG showed miscible with the high molecular weight polymer PEO. The X-ray diffraction patterns of PEO/PEG with KI salt indicated the decrease in the degree of crystallinity with increasing concentration of the salt. The DSC measurements of PEO/PEG:KI polymer electrolyte system showed that the melting temperature is shifted towards the lower temperature with increase of the salt concentration. Optical micrographs demonstrated that the spherulites of different sizes are present along with dark regions between the spherulites for lower salt compositions. With increase of salt concentration more amorphous regions are observed. The significance of blend is the increase of one order in ionic conductivity when compared to without blend PEO electrolyte.     

Electrical and structural properties enhancement in plasticized high Tg polymers using metal salts

Plasticized polymer electrolyte composite has been prepared in the form of a film by solution casting method. Poly (ethyl methacrylate) (PEMA) acts as a host polymer and is doped with Sodium Iodide (NaI). Ethylene carbonate (EC) added as a plasticizer and also enhances amorphicity of the polymer electrolyte. The electrical conductivity of the PEMA+NaI was evaluated using complex impedance spectroscopy. Maximum ionic conductivity obtained at room temperature was 8.75 × 10^?6 S/cm with the composition of PEMA: NaI (30%) + 60% EC. The conductivity further increased with increase in temperature and moved up to 5.8 × 10^?5 S/cm. Scanning electron microscopy was used to study the surface morphology of the composite film. Fourier transform infrared ray and X-ray diffraction data confirmed the complexation of material.