一种高离子电导率复合聚合物电解质的简易热处理制备

固态聚合物电解质是发展柔性全固态锂离子电池的核心,但是目前室温离子电导率低限制了其应用.本研究以热聚合方法制备石墨相氮化碳(g-C_3N_4),并将其与聚氧化乙烯/高氯酸锂(PEO/LiClO_4)共混制备复合聚合物固态电解质.采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、光学显微镜(OM)、扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和电化学工作站对复合聚合物电解质膜进行表征.结果表明,通过120℃退火-淬冷热处理及复合聚合物电解质内部的相互作用,可以较大程度抑制PEO的结晶,从而使该复合聚合物固态电解质膜的离子电导率在25℃时达到2.4×10~(-5)S cm~(-1),提高了3个数量级.     

高岭石-硬脂酸插层复合物的制备及结构模型的提出

以张家口高岭土为原料,通过直接插层与取代相结合的方法制备高岭石-硬脂酸插层复合物.利用 X射线粉末衍射、红外光谱、热重及透射电子显微镜对制备产物进行表征.结果表明:硬脂酸插入到高岭石层间,高岭石层间距d₀₀₁值由0.72 nm增加到4.05~4.37 nm,插层率达到86.9%;反应时间和溶液pH值会对高岭石-硬脂酸插层复合物的层间距及插层率产生影响;甲氧基嫁接在高岭石表面,与硬脂酸分子同时存在于高岭石层间.高岭石经甲醇改性后脱羟基温度明显降低,高岭石羟基活性提高;高岭石-硬脂酸插层复合物的稳定温度在160 ℃以下.经过硬脂酸插层改性后的高岭石片层,从边缘开始出现卷曲现象,并且部分长条状片层形成类似埃洛石相的纳米卷;对硬脂酸插层高岭石的作用机理进行分析,结合结构计算,提出高岭石-硬脂酸插层复合物的结构模型,该模型可以解释高岭石-硬脂酸插层复合物在不同条件制备产物层间距变化的原因.     

高岭石-硬脂酸插层复合物的制备及结构模型的提出

以张家口高岭土为原料,通过直接插层与取代相结合的方法制备高岭石-硬脂酸插层复合物。利用X射线粉末衍射、红外光谱、热重及透射电子显微镜对制备产物进行表征。结果表明:硬脂酸插入到高岭石层间,高岭石层间距d001值由0.72 nm增加到4.05~4.37 nm,插层率达到86.9%;反应时间和溶液p H值会对高岭石-硬脂酸插层复合物的层间距及插层率产生影响;甲氧基嫁接在高岭石表面,与硬脂酸分子同时存在于高岭石层间。高岭石经甲醇改性后脱羟基温度明显降低,高岭石羟基活性提高;高岭石-硬脂酸插层复合物的稳定温度在160℃以下。经过硬脂酸插层改性后的高岭石片层,从边缘开始出现卷曲现象,并且部分长条状片层形成类似埃洛石相的纳米卷;对硬脂酸插层高岭石的作用机理进行分析,结合结构计算,提出高岭石-硬脂酸插层复合物的结构模型,该模型可以解释高岭石-硬脂酸插层复合物在不同条件制备产物层间距变化的原因。     

PEO-LiClO4-ZSM5复合聚合物电解质Ⅱ.ZSM-5对离子电导率的影响

通过XRD,DSC,FT-IR和SEM等方法对PEO-LiClO₄-ZSM5复合电解质进行了研究,结果表明ZSM-5可以有效地降低PEO-LiClO₄-ZSM5复合电解质中PEO的结晶度和玻璃化温度,从而提高其低温区域的离子电导率.温度高于PEO的结晶熔融温度后,复合电解质离子电导率的提高则是由于在ZSM-5表面形成了有利于Li离子迁移的导电通道所引起的.较高的离子电导率和较宽的电化学稳定窗口表明PEO-LiClO₄-ZSM5复合电解质在全固态锂离子二次电池领域具有良好的应用前景.     

直接置换插层法0.85 nm水合高岭石的制备

以高岭石/尿素插层复合物作为中间相,利用简单的直接置换插层法制备了d001=0.85 nm的水合高岭石。利用X射线衍射、红外光谱、扫描电镜表征处理前后高岭石结构与形貌的变化。结果表明:尿素插层后的高岭石层间距从d001=0.72 nm增大到d001=1.08 nm,经不同温度酸洗或水洗后,插层复合物转变成层间有水分子的水合高岭石(d001=0.85 nm),且高岭石晶粒厚度明显从约25 nm减小到约10 nm。在高温条件下形成的水合高岭石含量最高,90℃水洗时d001=0.85 nm水合高岭石的转化率接近70%,这种水合高岭石具有进一步的置换插层能力,是一种制备其他高岭石插层复合物很好的前驱体。与乙二醇形成d001=1.10nm乙二醇/高岭石插层复合物,其置换率达到100%。     

PEO-LiClO_4-ZSM5复合聚合物电解质II.ZSM-5对离子电导率的影响

通过XRD ,DSC ,FT IR和SEM等方法对PEO LiClO4 ZSM5复合电解质进行了研究 ,结果表明ZSM 5可以有效地降低PEO LiClO4 ZSM5复合电解质中PEO的结晶度和玻璃化温度 ,从而提高其低温区域的离子电导率 .温度高于PEO的结晶熔融温度后 ,复合电解质离子电导率的提高则是由于在ZSM 5表面形成了有利于Li离子迁移的导电通道所引起的 .较高的离子电导率和较宽的电化学稳定窗口表明PEO LiClO4 ZSM5复合电解质在全固态锂离子二次电池领域具有良好的应用前景 .     

原位复合法制备(PEO)8LiClO4/TiO2聚合物电解质的研究

以聚氧化乙烯/高氯酸锂复合物[(PEO)8LiClO4]为基体,通过钛酸丁酯的水解缩合反应在其中原位生成TiO2,制备了(PEO)8LiClO4/TiO2复合聚合物电解质,采用SEM、DSC和交流阻抗方法研究了聚合物电解质的形态、玻璃化转变温度(Tg)、结晶度(Xc)和离子导电性能.结果表明原位生成的TiO2在基体中分散均匀,加入TiO2后聚合物电解质体系的Tg和Xc均有所降低,而电导率明显提高,当TiO2添加量为ω=0.05时电导率达到最大值5.5×10-5S·cm-1(20℃).     

PEG在微波诱导下对高岭石插层及剥片的研究

利用微波能量，快速制备了高岭石/DMSO插层复合物，并以其为前驱体，在熔融状态，微波诱导聚乙二醇(PEG)置换出高岭石层间的DMSO，微波继续协同PEG作用，可以实现其对高岭石的剥片。同时提出了微波作用机理和微波条件下插层物对高岭石的剥片机理。采用X-射线衍射、FTIR光谱、TG-DTA、TEM等技术对插层复合物进行了表征。     

Li1.5Al0.5Ge1.5(PO4)3基固体复合电解质的制备及锂离子导电行为

将聚氧化乙烯(PEO)和二(三氟甲基磺酰)亚胺锂(LiTFSI)混合(固定EO/Li摩尔比为13)后, 采用溶液浇注法制备了一系列不同Li_1.5Al_0.5Ge_1.5(PO₄)₃(LAGP)与PEO质量比的LAGP-PEO(LiTFSI)固体复合电解质体系. 结合电化学阻抗法、 表面形貌表征以及与惰性陶瓷填料(SiO₂, Al₂O₃) 性能的对比分析, 探讨了LAGP在固体复合电解质中的作用机理以及锂离子的导电行为. 结果表明, 在以LAGP为主相的固体复合电解质中, PEO主要处于无定形态, 整个体系主要为PEO与LiTFSI的络合相、 LAGP与PEO(LiTFSI)相互作用形成的过渡相和LAGP晶相. 其中LAGP作为主要的导电基体不仅起到降低PEO结晶度、 改善两相导电界面的作用; 同时自身也可以作为离子传输的通道, 降低锂离子迁移的活化能, 从而使离子电导率得到提高. 当LAGP与PEO的质量比为6:4时, 固体复合电解质的成膜性能最好, 离子电导率最高, 在30 ℃时为2.57×10^-5 S/cm, 接近LAGP的水平, 电化学稳定窗口超过5 V.     

高岭石/APTES插层复合物的表征及其脱嵌反应动力学

以高岭石/甲醇(K/M)复合物为前驱体,利用置换法制备出了高岭石/γ-氨丙基三乙氧基硅烷插层复合物(K/APTES),并应用XRD、FTIR、TEM、TG-DSC分析等表征手段对复合物进行了分析。结果表明:APTES分子的氨基与前驱体K/M的四面体硅氧烷基、嫁接在铝氧八面体表面上的甲氧基均发生键合作用形成氢键,APTES分子为两层倾斜排列于高岭石层间,倾角大小与温度有关。插层剂APTES破坏了高岭石层间的氢键,加剧了高岭石自身结构中硅氧四面体片层与铝氧八面体片层之间存在的错位,使得K/APTES插层复合物的部分片层卷曲变形。还针对复合物的插层剂APTES的脱嵌反应,采用Satava积分法和AcharBrindley-Sharp-Wendworth微分法相结合的动力学方法计算得到了完整的动力学三因子:活化能E=197.8 k J·mol-1,指前因子的对数lg(A/s-1)=14.60,最概然机理函数为:f(α)=[-ln(1-α)]-1,G(α)=α+(1-α)ln(1-α)。     

高岭土／羧甲基淀粉复合颗粒的制备及其协同电流变效应

通过二次插层取代法，以二甲基亚砜为前驱体，羧甲基淀粉二次插层取代制备 了高岭土/羧甲基淀粉纳米复合材料。结合XRD，FTIR，SEM和EDS等测试手段对复合 材料的结构进行了表征。研究结果发现，羧甲基淀粉经过二次插层取代引起了高岭 土片层之间的剥离，形成剥离型纳米复合材料。该复合材料制备成电流变液出现了 较大的协同效应，具有很好的电流变行为，并发现电流变性能与复合物中羧甲基淀 粉的含量有密切关系。     

Enhanced ionic conductivity of poly(ethylene oxide) (PEO) electrolyte by adding mesoporous molecular sieve LiAlSBA

Mesoporous molecular sieve LiAlSBA was prepared via an ion exchange process with mesoporous AlSBA directly, which has a regular 2D hexagonal structure with pore size about 7 nm. It was added into poly(ethylene oxide) (PEO) solid electrolyte as filler. The characteristics of the composite polymer electrolyte were determined by XRD, DSC, TGA, FTIR, PLM and electrochemical methods. Compared with bare PEO electrolyte, the adding of dispersed LiAlSBA powder improved the ionic conductivity of PEO polymer electrolyte more than three orders. The reason for it is that mesoporous LiAlSBA powder acts as crystal cores in PEO composite electrolyte and fines the crystallites, decreases the crystallinity, which provides much more continuous amorphous domain for Li⁺ moving easily in PEO electrolyte. Besides, lithium ions of the mesoporous molecular sieves can hop from one site to another along the surface of the mesoporous channels, this mechanism is absent in the case of common nano-ceramic fillers in PEO electrolyte.     

Ion conducting properties of poly(ethylene oxide)-based electrolytes incorporating amorphous silica attached with imidazolium salts

Poly(ethylene oxide) (PEO)-based polymer electrolytes containing amorphous silica attached ionic liquid (IL) were studied in order to improve electrochemical and interfacial properties. An imidazolium salt such as IL was attached to modified ceramic fillers. The modified ceramic fillers were amorphous silica with the immobilized 1-methyl-3-propyl-imidazolium bromide (MPIm-AS). PEO-based polymer electrolytes were prepared by using the solution casting technique. In order to investigate the ionic conductivity, studies on the modified filler addition effects on the ion-conducting behavior of polymer electrolytes having specific amounts of MPIm-AS were carried out. The addition of MPIm-AS in polymer electrolytes has resulted in higher ionic conductivity at room temperature. The structure, crystallinity, and morphology of the solid polymer electrolytes were evaluated using X-ray diffraction, differential scanning calorimetry, and scanning electron microscope measurement. The ionic conductivity was measured by an AC impedance method. The enhanced conductivity was dependent on the decreased crystallinity and the changed morphologies of composites.     

高岭土对不饱和聚酯树脂的热稳定性、阻燃及力学性能的影响

不饱和聚酯树脂;高岭土;纳米复合材料;原位聚合;阻燃;成炭     

A novel PEO-based composite solid-state polymer electrolyte with methyl group-functionalized SBA-15 filler for rechargeable lithium batteries

Functionalized molecular sieve SBA-15 with trimethylchlorosilane was used as an inorganic filler in a poly(ethyleneoxide) (PEO) polymer matrix to synthesize a composite solid-state polymer electrolyte (CSPE) using LiClO₄ as the doping salts, which is designated to be used for rechargeable lithium batteries. The methyl group-functionalized SBA-15 (^fSBA-15) powder possesses more hydrophobic characters than SBA-15, which improves the miscibility between the ^fSBA-15 filler and the PEO matrix. The interaction between the ^fSBA-15 and PEO polymer matrix was investigated by scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry. Linear sweep voltammetry and electrochemical impedance spectroscopy were employed to study the electrochemical stability windows, ionic conductivity, and interfacial stability of the CSPE. The temperature dependence of the change of the PEO polymer matrix in the CSPE from crystallization to amorphous phase was surveyed, for the first time, at different temperature by Fourier transform infrared emission spectroscopy. It has demonstrated that the addition of the ^fSBA-15 filler has improved significantly the electrochemical compatibility of the CSPE with a lithium metal electrode and enhanced effectively the ion conductivity of the CSPE. Dedicated to Professor Oleg Petrii on the occasion of his 70th birthday on August 24th, 2007.     

A study on the intercalation and exfoliation of illite

Illite particles were exfoliated from the illite-organics intercalation precursor in the ultrasound process. Four intercalating agents (glycerol, hydrazine hydrate, dimethyl sulfoxide, and urea) were selected to study the intercalation reaction for purified illite, thermal activated illite, and acidified illite and to prepare different illite-organics intercalation complexes. The resulting intercalation complexes and exfoliated illite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), the zeta potential test, the particle size test and thermogravimetry analysis (TG). XRD results showed that the thermal activation and subsequent acidification treatment to exchange K⁺ in the interlayer of illite with H⁺ is a necessary condition for organic intercalation. FTIR and TG analysis confirmed the intercalation of four intercalating agents into the interlayer of illite. During the high-temperature ultrasonic treatment, the organic molecules were deintercalated from the interlayers of illite-organics intercalation complexes, leading to the separation of the illite layers. The d₀₀₁ diffraction of illite in XRD patterns became broad and weak after ultrasonic treatment; this indicated the random orientation of illite platelets. Particle size analysis showed the exfoliated illite (IUE) from the illite-urea intercalation complex possessed the smaller particle diameter. SEM and TEM observation showed the particle size of IUE is 0.5–4 μm with a layer thickness of approximately 200–300 nm. Moreover, the exfoliation of illite layers exposed more internal layers with negative charge, leading to the decrease of zeta potential.     

Electrochemical properties of PEO/PMMA blend-based polymer electrolytes using imidazolium salt-supported silica as a filler

In this study, the composite polymer electrolytes (CPEs) were prepared by solution casting technique. The CPEs consisted of PEO/PMMA blend as a host matrix doped with LiClO₄. Propylene carbonate (PC) was used as plasticizer and a small amount of imidazolium salt-supported amorphous silica (IS-AS) as a filler was prepared by the sol–gel method. At room temperature, the highest conductivity was obtained for the composition having PEO–PMMA–LiClO₄–PC–4wt. % IS-AS with a value of 1.15 × 10^?4 S/cm. In particular, the CPE using the IS-AS filler showed a higher conductivity than any other sample (fumed silica, amorphous silica). Studies of differential scanning calorimetry and scanning electron microscopy indicated that the ionic conductivity increase was due to an expansion in the amorphous phase which enhances the flexibility of polymeric chains and the homogeneous structure of CPEs. It was found that the ionic conductivity and interfacial resistance stability of CPEs was significantly improved by the addition of IS-AS. In other words, the resistance stability and maximum ambient ionic conductivity of CPEs containing IS-AS filler were better than CPEs containing any other filler.     

Improved polyvinylpyrrolidone (PVP)/graphite nanocomposites by solution compounding and spray drying

In order to evaluate the roles of graphite dispersion on the functional properties of the composites, PVP/graphite nanocomposites were prepared by blending the aqueous suspension of expanded graphite sheets and polyvinylpyrrolidone (PVP) aqueous solution by ultrasonic treatment, followed by spray drying and direct drying as a comparison individually. The effects of graphite loading and drying method on the dispersion of graphite and the resultant properties of the composites such as electrical and thermal conductivity, friction, and dynamic mechanical properties were studied. The results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction showed that the composites prepared by fast spray drying exhibited a higher degree of exfoliation and a better dispersion of graphite sheets in the PVP matrix than the corresponding composites prepared by direct drying, leading to a conclusion that fast spray drying can effectively prevent from re‐stacking of the exfoliated graphite sheets as illustrated. As a result, dynamic mechanical thermal analysis showed significant increases in the storage modulus and glass transition temperature for the composites prepared by spray drying. Besides, the spray drying as well greatly improved the electrical and thermal conductivity of the composites. It was also found that the electrical and thermal conductivity of the composites strongly depended on the graphite dispersion, while the friction coefficient unexpectedly does not. Increasing graphite loading level might enhance the probability of graphite sheets re‐stacking, resulting in poor graphite dispersion. Copyright © 2011 John Wiley & Sons, Ltd.     

Composites of Polystyrene Sulfonic Acid (PSSA)‐Polyaniline and Montmorillonite Clay: Synthesis and Characterization

Polystyrene sulfonic acid (PSSA) doped water‐soluble polyaniline (PANI)/montmorillonite (MMT) clay composites were synthesized by intercalation polymerization in aqueous medium. The properties of the composites were characterized by X‐ray diffraction (XRD), transmission electron microscope (TEM), Fourier‐transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray photoelectron spectroscopy (XPS) and conductivity measurement. The results show that the composite has a mixed nanomorphology and exfoliated silicate nanolayers of MMT clay dispersed in the polyaniline matrix. This composite is more thermal stable than that without clay samples and results in good stable temperature‐dependent dc conductivity [σ_dc(T)] as temperature changed.