添加TiO2的聚合物电解质膜PVDF-HFP的性能研究

通过添加不同质量分数的TiO2纳米粒子制备多孔聚合物电解质膜PVDF-HFP,制备的聚合物电解质膜通过红外,交流阻抗,线性伏安扫描、首次充放电测试等方法进行了性能测试。添加TiO2纳米填料后,降低了聚合物链的结晶度和极性,当填料的质量分数为8%时,表现出较好的电化学性能,吸液率为184%,孔隙率为93%,室温电导率达到2.05×10-3 S/cm,电化学稳定窗口为4.7V,能满足要求。     

聚偏氟乙烯-六氟丙烯聚合物锂电隔膜的制备及形貌研究

选择涂敷机刮膜,分别采用两种制膜技术用聚偏氟乙烯-六氟丙烯(PVDFHFP)树脂制备了锂电隔膜,并研究了PVDF-HFP的固含量、制膜温度、制膜方法和溶剂体系对于膜形貌的影响。     

直接挥发法制备无纺布增强型聚合物电解质

以N,N-二甲基-甲酰胺(DMF)为溶剂, 采用直接挥发法制备无纺布增强型聚偏氟乙烯-六氟丙烯(PVDF-HFP)聚合物电解质, 并以锂为负极制备了聚合物电池.用扫描电子显微镜、交流阻抗和循环伏安对所制聚合物膜性能进行了表征,用充放电实验对所制聚合物电池电化学性能进行了测试.实验结果表明,直接挥发法制得的聚合物膜孔穴丰富,微孔呈蜂窝状,吸液率为280%,电化学稳定窗口为4.5V,浸取电解液后室温离子电导率为1.5mS/cm;以LiCoO2为正极制得的聚合物电池0.1C充放电, 放电平台为3.9V左右, 首次放电容量为137.5mAh/g,20次循环后容量保持在134mAh/g以上,充放电库仑效率高于95%,0.5C放电时放电平台为3.7V,0.5和1C放电分别能保持0.1C放电容量的96%和93%.     

Nanostructured PVDF-HFP membranes loaded with catalyst obtained by supercritical CO2 assisted techniques

Polymeric catalytic membrane reactors offer a larger flexibility over conventional reactors. The most-used method to generate polymer-based catalytic membranes is the phase inversion that, however, presents some limitations; in particular, the difficulty in generating a uniform distribution of the loaded materials.In this work, we use two new processes for the formation of membranes loaded with catalyst for potential applications in catalysis: supercritical assisted phase inversion and supercritical assisted gel drying, applied to formation of poly(vinylidene fluoride-co-hexafluoropropylene) membranes loaded with palladium nanoparticles. We analyzed the effect of process parameters (polymer concentration, catalyst concentration, pressure, temperature) on the membranes morphology. The supercritical phase inversion process produced cellular asymmetric structures with cell size ranging between 3 and 6 μm and nanoporous homogeneous networks, depending on the process conditions. Palladium nanoparticles homogeneous distributions were obtained only operating at selected process conditions, i.e., pressures larger than 150 bar and temperatures lower than 45 °C.Supercritical gel drying allowed homogeneous nanoporous membranes formation at all the tested process conditions: they were characterized by very high porosity (higher than 90%) and a very uniform catalyst distribution.     

PVDF-HFP锂离子电池膜的研究进展

PVDF-HFP材料具有耐化学腐蚀、耐热性好、机械性能优等特点,有望成为锂离子电池隔膜材料.总结了PVDF-HFP的形态结构优势和PVDF-HFP膜的改性研究,并展望了PVDF-HFP膜未来改性研究的趋势.     

Modified sepiolite/PVDF-HFP composite film with enhanced piezoelectric and dielectric properties

Flexible film with both piezoelectric and dielectric properties is considered to be a potential candidate for the energy conversion and storage devices. In this study, the Li⁺ and H₂O modified sepiolite/poly(vinylidene fluoride-co-hexafluoropropylene) (LiSEP-H₂O/PVDF-HFP) composite films with both good piezoelectric and dielectric properties were prepared by traditional coating process. When the H₂O content was 13 wt %, the LiSEP-H₂O/PVDF-HFP composite exhibited high d₃₃ of 32 and dielectric constant of 48. Moreover, the effects of the Li⁺ and adsorbed H₂O on the d₃₃, F(β), dielectric constant, short-circuit currents were discussed. The adsorbed H₂O enhanced the β-phase by the hydrogen bonds and Li⁺ improved the polarization to realize the composite film with increased piezoelectric and dielectric properties respectively. We expected the common modification to lead other clay minerals realizing the future applications in the adjustment of composites' electric properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48412.     

Preparation of hydrophobic flat sheet membranes from PVDF-HFP copolymer for enhancing the oxygen permeance in nitrogen/oxygen gas mixture

In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure,morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate(1–5 L·min~(-1)), inlet pressure to membrane module(0.1–0.5 MPa) and temperatures between 25 and 45 °C. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol,coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and115 μm. Besides, the values of 4.7504 × 10~(-7) mol· m~(-2)· s~(-1)· Pa~(-1), 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O_2/N_2 selectivity and roughness, respectively.     

不同基体对金属锂负极性能的影响

对不同基体及其上预制SEI膜后制备的扣式电池进行循环伏安、交流阻抗等电化学性能测试,以及对不同基体材料进行扫描电镜、亲锂性能等测试。结果显示,以不同材料为基体时,基体表面的粒子形貌对其上预制SEI膜和沉积金属锂的一次晶粒的形貌具有一定的诱导作用,从而影响其上预制SEI膜和沉积的金属锂的形貌,使不同基体上预制SEI膜的扣式电池的沉积/脱出锂的循环性能差异显著。当以涂炭铜箔为基体时,预制SEI膜的扣式电池的库伦效率高于99.0%,稳定循环次数高达820次,性能最优。     

Silicate-based polymer-nanocomposite membranes for polymer electrolyte membrane fuel cells

Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion^® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 °C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion^® above 80 °C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. However, the degrees of dispersion and interaction between the organic polymer and inorganic silicates play vital roles in improving the key properties of the membranes. Hence, different techniques and solvent media were used to improve the degrees of nanofiller dispersion and the physico-chemical properties of the membranes. This review focuses mainly on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties.     

PVDF-HFP基聚合物电解质膜的制备及性能表征

采用相转化法制备了PVDF-HFP基多孔聚合物电解质,研究了PVDF-HFP的溶解温度、溶剂用量以及非溶剂用量等因素对聚合物电解质性能的影响,分别采用交流阻抗法和稳态电流法测定了聚合物电解质膜的离子电导率和离子迁移数,并通过扫描电镜观察了多孔聚合物膜的表面形貌.研究表明,制备PVDF-HFP多孔聚合物电解质膜的合适条件为:溶胶温度50~60℃、溶胶时间2 h、溶剂与PVDF的质量比为9~11、非溶剂与PVDF的质量比为0.5~0.25.该条件下制得的多孔聚合物电解质膜的孔隙率达到70%左右、离子迁移数在0.3左右、室温离子电导率达到1.6×10-3S.cm-1.