纳米 SiO 2/ LiClO 4/ PVDF2 HFP复合凝胶聚合物电解质的制备及其电化学性能

为了解决液态电解质锂离子电池存在的安全性问题 , 以偏氟乙烯和六氟丙烯的共聚物( PVDF2 HFP)为基体 , 通过加入高氯酸锂(LiClO 4) 、 增塑剂(碳酸丙烯酯和碳酸二甲酯) 、 纳米二氧化硅等 , 制备出了具有高电导率的复合凝胶聚合物电解质。用 X射线衍射仪测试聚合物电解质的结构 , 用交流阻抗法测定其电导率 , 用线性伏安扫描法研究了该聚合物电解质体系的电化学稳定性 , 并以其为电解质制备成锂离子电池进行充放电测试。结果- 3表明 , 在 20℃ 时复合凝胶聚合物电解质的电导率最高可达 7. 56×10 S/ cm , 该电解质在 41 6 V 以下电化学窗口稳定 , 以其为电解质的锂离子电池具有良好的电化学性能 , 说明纳米 SiO 2/ LiClO 4/ PVDF2 HFP复合凝胶聚合物电解质能满足锂离子电池的应用。     

锂离子电池用PVDF/P(MMA-co-DMAEMA)共混隔膜的制备与性能

首先合成了甲基丙烯酸甲酯(MMA)与甲基丙烯酸-N,N-二甲胺乙酯的共聚物P(MMA-co-DMAE-MA),与聚偏氟乙烯(PVDF)共混经溶液相转化法制备了PVDF/P(MMA-co-DMAEMA)隔膜。研究发现,相对于纯PVDF隔膜,共混隔膜的孔隙率增加,结晶度降低,电解液吸收稳定性显著提高。共混隔膜具有"活性"隔膜的性质,隔膜-电解液组成的电解质体系表现出凝胶电解质特征,隔膜中PVDF/P(MMA-co-DMAE-MA)质量比为10/1时,隔膜吸液率在420%以上,活化后凝胶电解质膜离子电导率可达到1.8×10-3S/cm。研究结果表明,采用溶液相转化法制备PVDF/P(MMA-co-DMAEMA)共混隔膜,是一种制备凝胶锂离子电池用高性能活性隔膜的有效方法。     

纳米SiO2/LiClO4/PVDF-HFP复合凝胶聚合物电解质的制备及其电化学性能

为了解决液态电解质锂离子电池存在的安全性问题,以偏氟乙烯和六氟丙烯的共聚物(PVDF-HFP)为基体,通过加入高氯酸锂(LiC1O4)、增塑剂(碳酸丙烯酯和碳酸二甲酯)、纳米二氧化硅等,制备出了具有高电导率的复合凝胶聚合物电解质.用X射线衍射仪测试聚合物电解质的结构,用交流阻抗法测定其电导率,用线性伏安扫描法研究了该聚合物电解质体系的电化学稳定性,并以其为电解质制备成锂离子电池进行充放电测试.结果表明,在20℃时复合凝胶聚合物电解质的电导率最高可达7.56×10-3S/cm,该电解质在4.6 V以下电化学窗口稳定,以其为电解质的锂离子电池具有良好的电化学性能,说明纳米SiO2/LiC1O4/PVDF-HFP复合凝胶聚合物电解质能满足锂离子电池的应用.     

SiO_2涂层对TiC/PVDF复合材料介电性能的影响研究

为降低碳化钛(TiC)/聚偏氟乙烯(PVDF)体系的介电损耗,通过溶胶-凝胶法在TiC粒子表面包覆SiO_2绝缘层,形成SiO_2@TiC核壳结构粒子,再与PVDF复合,制备出SiO_2@TiC/PVDF复合材料。研究结果表明,TiC表面成功包覆上SiO_2涂层;在质量分数为9%的TiC或SiO_2@TiC总用量时,SiO_2@TiC/PVDF的损耗因子相比TiC/PVDF明显降低,随SiO_2包覆量的增加,SiO_2@TiC/PVDF的介电常数、损耗因子和电导率均下降;包覆量相同时,随SiO_2@TiC粒子含量增加,SiO_2@TiC/PVDF的介电常数、电导率、损耗因子均逐步增大。     

聚醚侧链型聚硅氧烷对含氟聚合物凝胶锂离子电解质膜性能的影响

通过浸没沉淀相转化法制备了具有类似孔结构的聚醚侧链型聚硅氧烷(PDMS-g-(PPO-PEO))改性的聚偏氟乙烯(PVDF)和聚偏氟乙烯-六氟丙烯(PVDF-HFP)多孔骨架,经电解液活化后得到凝胶电解质膜,研究了PDMS-g-(PPO-PEO)对含氟聚合物凝胶电解质膜性能的影响。由改性PVDF和PVDF-HFP骨架被电解液活化制备的聚合物凝胶电解质膜,离子电导率分别达到2.2×10-3和1.7×10-3S/cm,综合分析凝胶电解质膜中电解液稳定性和膜的电化学性能发现,PDMS-g-(PPO-PEO)对PVDF骨架的改性效果明显优于PVDF-HFP骨架,共混改性后PVDF可代替PVDF-HFP作为隔膜作为锂离子电池凝胶电解质膜。     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率。结果表明,SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20%时,膜的含水率和溶胀度分别达到18%和2.1%。通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20%的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm。     

磺化聚苯醚-磷酸锆质子交换复合膜的制备与性能研究

开发价格低廉且性能优异的质子交换膜是目前燃料电池研究的热点.采用溶胶-凝胶法将磺化聚苯醚(SPPO)与磷酸锆(ZrP)复合得到质子交换膜,重点考察了ZrP含量对复合膜含水率、溶胀度和质子电导率的影响,采用红外光谱和交流阻抗法表征SPPO-ZrP复合膜的微观结构和质子电导率.结果表明SPPO与ZrP产生相互作用使SPPO结构发生变化.SPPO-ZrP复合膜含水率和溶胀度都随着ZrP质量分数增加而逐渐减小,当ZrP质量分数为20％时,膜的含水率和溶胀度分别达到18％和2.1％.通过交流阻抗法对质子传导性能的表征结果显示,随ZrP质量分数增加复合膜质子电导率逐渐增大,ZrP质量分数20％的SPPO-ZrP复合膜质子电导率在室温下达到1.6×10-2S/cm.     

P(MMA-MAh)基凝胶聚合物电解质导锂离子性能研究

以甲基丙烯酸甲酯(MMA)和马来酸酐(MAh)单体合成共聚物P(MMA-MAh),并以其为聚合物基体制备了凝胶聚合物电解质。采用傅里叶红外光谱(FT-IR)、差示扫描量热法(DSC)和热失重分析(TGA)对合成共聚物进行了表征,并采用交流阻抗法对制备的凝胶聚合物电解质(GPE)的导锂离子性能作了研究,并且分析了不同温度和配比对其离子电导率的影响。结果表明:成功合成了聚合物P(MMA-MAh),其热分解温度为300℃,玻璃化转变温度为133.9℃,制备的GPE的离子电导率随温度的升高而增大,随聚合物含量的增加而减小,且在研究温度范围内锂离子迁移符合Arrhenius方程。     

CoFe_2O_4/PVDF复合材料介电和磁性能研究

为增强聚偏氟乙烯(PVDF)的介电性能和磁性能,以湿法化学法合成的纳米铁酸钴(CoFe_2O_4)和PVDF为原料,通过粉末热压法制备了CoFe_2O_4/PVDF复合材料,并对其介电性能和磁性能进行了研究。结果表明,成功合成了纳米CoFe_2O_4,CoFe_2O_4在PVDF基体中分散均匀;与纯PVDF相比,随CoFe_2O_4掺杂量的增加,复合材料的介电常数、电导率、损耗因子均逐步增大;12%(wt,质量分数)CoFe_2O_4掺杂量时,复合材料的介电常数达18.7,介电损耗仅为0.11;复合材料为硬磁材料;复合材料的击穿电压与击穿场强随CoFe_2O_4掺杂量的增加先增大后减小。     

热致相分离法（TIPS）制备PVDF聚合物电解质多孔骨架

凝胶聚合物锂离子电池的关键技术之一是制备聚合物电解质，要求聚合物电解质具有高的离子传导率、适宜的机械强度、柔韧性、孔结构和电化学稳定性等,利用三乙酸甘油酯（GT）作为稀释剂，通过热致相分离（TIPS）法制备了PVDF多孔骨架，然后将多孔膜浸入LiPF6EC／DMC／EMC电解液中通过凝胶相转变制得PVDF凝胶电解质．分析研究了冷却条件与聚合物浓度对多孔膜结构以及性能的影响，发现在15℃冷却浴下PVDF浓度为30％的多孔膜具有较好的吸液率和力学性能，由此制得的凝胶聚合物电解质的电导率为1．21mS／cm。     

Preparation and proton conductivity of poly(vinylidene fluoride)/layered double hydroxide nanocomposite gel electrolytes

Layered double hydroxide (LDH) was synthesized in the presence of sodium dodecyl sulfate. X-ray diffraction (XRD) and infrared spectrum revealed that dodecyl sulfate (DS) anions were successfully intercalated into the interlayers of LDH. Poly(vinylidene fluoride)/LDH nanocomposite membranes were prepared by mixing the DS intercalated LDH with poly(vinylidene fluoride) (PVDF) in N,N’′-dimethylformamide solution followed by the solvent evaporation. The nanocomposite membranes were further swollen with a H₃PO₄ solution in ethylene carbonate-propylene carbonate to obtain the proton conducting nanocomposite gel electrolytes. XRD and transmission electron microscope results showed that LDH particles were well-dispersed in the polymer matrix and partially intercalated by polymer chains. The proton conductivity was highly enhanced in the nanocomposite gel electrolyte systems. In the case of the nanocomposite gel electrolyte containing 7.40 wt.% LDH, the proton conductivity increased by about 2.5 times compared to pure PVDF gel electrolyte.     

Characterization, microstructure, and gas sensitive response behavior of PEG/lithium salt polymer electrolyte films

A composite polymer electrolyte film was prepared by dissolving polyethylene glycol (PEG) with different molecular weight in acetonitrile, and vapor-induced response behavior was investigated upon exposure to various chemical environments. The effect of lithium concentrations on ionic conductivity and response was discussed. The surface microporous structures and vapor sensitive conductivity of the films in the case of poly(vinylidene fluoride) (PVDF) were examined with the PVDF content changed. The crystalline and micro-phase isolation behavior were characterized by a differential scanning calorimeter, an environmental scanning electron microscope, a polarization microscope and a wide-angle X-ray diffraction. The experimental results indicated that PEG/Li⁺ salt composite films exhibited preferential responsive characteristics. The responsivities to ethanoic acid, chloroform, and acetone vapors were enhanced with molecular weight of PEG increased. The conductivity was increased at a higher lithium salt concentration, and also enhanced with PEG content increased, while the responsivities decreased. The formation of microporous structures on the surface of the mixed PEG/PVDF composite films enlarged their specific area and strikingly improved the responsive performances. The changes in conduction behavior were explained from the viewpoint of the swelling and free volume theories as well as a hydrogen bond interaction, combined with the structural and morphological analyses. The introduction of an ionogenic matter also has an important effect on ionic conductivity and responsiveness.     

Conductivity behaviour of polymer gel electrolytes: Role of polymer

Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.     

Interfacial Interaction of Multifunctional GQDs Reinforcing Polymer Electrolytes For All-Solid-State Li Battery

Solid-state polymer electrolytes are highly anticipated for next generation lithium ion batteries with enhanced safety and energy density. However, a major disadvantage of polymer electrolytes is their low ionic conductivity at room temperature. In order to enhance the ionic conductivity, here, graphene quantum dots (GQDs) are employed to improve the poly (ethylene oxide) (PEO) based electrolyte. Owing to the increased amorphous areas of PEO and mobility of Li⁺, GQDs modified composite polymer electrolytes achieved high ionic conductivity and favorable lithium ion transference numbers. Significantly, the abundant hydroxyl groups and amino groups originated from GQDs can serve as Lewis base sites and interact with lithium ions, thus promoting the dissociation of lithium salts and providing more ion pathways. Moreover, lithium dendrite is suppressed, associated with high transference number, enhanced mechanical properties and steady interface stability. It is further observed that all solid-state lithium batteries assembled with GQDs modified composite polymer electrolytes display excellent rate performance and cycling stability.     

Enhanced performance of 4,4′-bipyridine-doped PVDF/KI/I<Subscript>2</Subscript> based solid state polymer electrolyte for dye-sensitized solar cell applications

Pure (PVDF/KI/I₂) and 4,4′-bipyridine-doped PVDF/KI/I₂ solid state polymer electrolytes were prepared by solution casting method using N,N-dimethylformamide (DMF) as solvent. The solid state polymer electrolytes were characterized by the powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR), AC-impedance, dielectric measurements and scanning electron microscopy (SEM) analysis. The crystallinity of the solid state polymer electrolytes was analyzed by PXRD measurement. The functional groups of the solid state polymer electrolytes were confirmed by FTIR analysis. The AC-impedance analysis was carried out to calculate the ionic conductivity of the solid state polymer electrolytes. The ionic conductivity value of pure (PVDF/KI/I₂) and 4,4′-bipyridine-doped PVDF/KI/I₂ solid state polymer electrolytes are 2.00?×?10^?6 S cm^?1 and 4.60?×?10^?5 S cm^?1, respectively. The dielectric properties of solid state polymer electrolytes were calculated by using the dielectric measurements. From the SEM analysis, the surface morphology of the solid state polymer electrolytes was analyzed. The power conversion efficiencies of pure (PVDF/KI/I₂) and 4,4′-bipyridine-doped PVDF/KI/I₂ solid state polymer electrolytes are 1.8% and 4.4%, respectively. 4,4′-bipyridine-doped PVDF/KI/I₂ solid state polymer electrolyte has higher power conversion efficiency due to its increased amorphous nature and ionic mobility.     

聚合物复合固体电解质材料研究进展

固体电解质是发展高安全、高能量密度全固态锂电池的重要材料基础。由聚合物相与无机相复合形成的聚合物复合固体电解质,兼具聚合物轻质、柔性,以及无机材料高强度、高稳定性等优势,是最具应用潜力的固体电解质材料。目前,制约聚合物复合固体电解质实际应用的主要瓶颈问题为其室温离子电导率较低。综述了目前关于聚合物复合固体电解质离子传导机制的科学认识以及提升其离子电导率的方法,分析了先进表征工具在揭示聚合物复合固体电解质离子传导机制方面的应用潜力,并展望了聚合物复合固体电解质未来的发展方向和工作重点。     

Creating Lithium‐Ion Electrolytes with Biomimetic Ionic Channels in Metal–Organic Frameworks

Solid‐state electrolytes are the key to the development of lithium‐based batteries with dramatically improved energy density and safety. Inspired by ionic channels in biological systems, a novel class of pseudo solid‐state electrolytes with biomimetic ionic channels is reported herein. This is achieved by complexing the anions of an electrolyte to the open metal sites of metal–organic frameworks (MOFs), which transforms the MOF scaffolds into ionic‐channel analogs with lithium‐ion conduction and low activation energy. This work suggests the emergence of a new class of pseudo solid‐state lithium‐ion conducting electrolytes.     

DSC and conductivity studies on PVA based proton conducting gel electrolytes

An attempt has been made in the present work to prepare polyvinyl alcohol (PVA) based proton conducting gel electrolytes in ammonium thiocyanate (NH₄SCN) solution and characterize them. DSC studies affirm the formation of gels along with the presence of partial complexes. The cole-cole plots exhibit maximum ionic conductivity (2.58 × 10⁻³ S cm⁻¹) for gel samples containing 6 wt% of PVA. The conductivity of gel electrolytes exhibit liquid like nature at low polymer concentrations while the behaviour is seen to be affected by the formation of PVA-NH₄SCN complexes upon increase in polymer content beyond 5 wt%. Temperature dependence of ionic conductivity exhibits VTF behaviour.     

Effect of plasticizer and fumed silica on ionic conductivity behaviour of proton conducting polymer electrolytes containing HPF6

The effect of addition of propylene carbonate (PC) and nano-sized fumed silica on the ionic conductivity behaviour of proton conducting polymer electrolytes containing different concentrations of hexafluorophosphoric acid (HPF₆) in polyethylene oxide (PEO) has been studied. The addition of PC results in an increase in ionic conductivity, whereas the addition of nano-sized fumed silica improves mechanical strength of electrolytes along with a small increase in ionic conductivity. It was observed that the simultaneous addition of PC and fumed silica results in electrolytes with optimum value of ionic conductivity and other properties.