锂磷氧氮电解质薄膜制备与性能研究

首次采用355nm脉冲激光沉积(PLD)法在N2压强26.6Pa、激光能量密度15J/cm2、靶-基片距离5cm、基片温度为室温条件下制备了室温离子电导率为1.6×10-6S/cm、厚度均匀、无针孔、无裂缝的非晶态LiPON电解质薄膜。考察了反应气氛压强、激光能量密度对LiPON薄膜电化学性能的影响,并利用台阶仪、XPS、EDX、SEM等分析方法对薄膜进行表征。     

PEG对二氧化钛薄膜的微观结构和染料吸附性能的影响

用PEG作为添加剂,用溶胶-凝胶法制备了多孔二氧化钛薄膜,通过改变热处理温度和PEG的添加量获取不同微观结构的二氧化钛薄膜,进而研究制备条件对染料吸附的影响。样品的X射线衍射、折射率、扫描电镜(SEM)和吸收光谱的测试结果表明,PEG加入越多,气孔率越大．染料的吸附量越多。另外,热处理温度为500℃时染料的吸附量最好。     

Evaluation of a cross-linked polyurethane acrylate as polymer electrolyte for lithium batteries

A cross-linked polyurethane acrylate (CL-PUA) was synthesized by end capping 2,6-toluene diisocyanate (TDI)/poly(ethylene glycol) (PEG) based prepolymer with hydroxybutyl methacrylate (HBMA). Differential scanning calorimetry (DSC) and Fourier transform infra-red (FT-IR) spectroscopy measurements reveal the possible presence of significant interactions between lithium ions and soft/hard segments of the CL-PUA, when CL-PUA was complexed with lithium perchlorate (LiClO₄). CL-PUA follows the VTF relationship for the ion transport. Predominant formation of contact ion pairs of LiClO₄ has been observed through AC conductivity and DSC measurements. The lithium stripping–plating process is a reversible and implies better electrochemical stability in the working voltage range. Also, CL-PUA electrolyte shows better compatibility with lithium metal as inferred from impedance measurements and has a good cationic transference number suitable to be used as a solid polymer electrolyte. The addition of HBMA into PU matrix improves tensile strength of the CL-PUA. Swelling measurements of CL-PUA with plasticizer showed better dimensional stability. Also, a cell was constructed using CL-PUA as electrolyte and the performance was assessed.     

Electrochemical performance of poly(vinyl alcohol)-based solid polymer electrolyte for lithium polymer batteries

Solid polymer electrolytes (SPEs) are an excellent alternative to liquid electrolytes due to their non-volatility, low toxicity, and high energy density. In this study, a SPE having the ion transport mechanism decoupled from segmental motion of a polymer based on poly(vinyl alcohol) (PVA) containing the salt lithium trifluoromethane sulfonate (LiCF3SO3, LiTf) has been prepared to overcome the low ionic conductivity of traditional SPEs at room temperature. PVA has a high glass transition temperature (358 K) and good mechanical properties, and despite being atactic, it can crystallize, especially if highly hydrolyzed. From an ac impedance analysis, it was found that the ionic conductivity of the PVA-based SPE increased with increasing salt concentration. In particular, a dramatic increase was observed between 40 and 50 wt% of salt. The ionic conduction mechanism of the PVA-based SPE is proposed based on intensive study using FT-IR spectroscopic measurements, XRD and AFM. Through measurements of linear sweep voltammetry (LSV) and cyclic voltammetry (CV), it is also found that the SPE with PVA and LiCF3SO3 has good electrochemical stability.     

The anisotropic gas response behavior of LB films of an amphiphilic asymmetrically substituted phthalocyanine

1,4-Di(2-hydroxyethoxy)-9,10,16,17,23,24-hexapentyloxy phthalocyanine (asy-Pc) has been deposited as well-ordered Langmuir–Blodgett (LB) films on a glass substrate and glass-bearing interdigital electrodes. The molecular orientation of the asy-Pc LB films has been characterized by polarized UV-vis absorption spectra and in-plane dichroism has been observed. The LB films show good room temperature response to NO₂ gas and the recovery is almost complete. It has been found that the magnitude of the response increases with increasing gas concentration and is also dependent upon the LB dipping direction relative to the arms of the electrodes, consistent with conduction being favored along the axes of the stacks of asy-Pc molecules.     

全固态锂电池中金属锂负极及其界面设计的研究进展

锂金属具有低的氧化还原电位(-3.04 V vs标准氢电极)和高比容量(3860 mAh/g),是理想的锂二次电池负极材料.由金属锂负极/固态电解质/嵌锂正极组装的固态锂电池,有望成为未来航空航天、机器人、高端电子和电动汽车等相关技术产业的动力源.然而,在充放电过程中,由于锂的不均匀沉积-溶解造成锂与电解质接触面产生大量树枝状枝晶,并沿着电解质方向不断生长,最终造成电池内部短路而失效.使用较高杨氏模量的固态电解质,可以很大程度上阻挡锂枝晶的生长,但仍不能满足电池长循环和安全性的要求.此外,金属锂与固态电解质表面是固固接触,造成了界面电阻大以及金属锂与固态电解质的界面反应等问题,这严重阻碍了固态锂金属电池的发展与使用.本文综述了近年来基于固态电解质的金属锂电池抑制锂枝晶生长和提高固固界面相容性的相关策略,并对金属锂/固态电解质界面设计的发展趋势进行展望.     

Nanocomposite metal/plasma polymer films prepared by means of gas aggregation cluster source

Nanocomposite metal/plasma polymer films have been prepared by simultaneous plasma polymerization using a mixture of Ar/n-hexane and metal cluster beams. A simple compact cluster gas aggregation source is described and characterized with emphasis on the determination of the amount of charged clusters and their size distribution. It is shown that the fraction of neutral, positively and negatively charged nanoclusters leaving the gas aggregation source is largely influenced by used operational conditions. In addition, it is demonstrated that a large portion of Ag clusters is positively charged, especially when higher currents are used for their production. Deposition of nanocomposite Ag/C:H plasma polymer films is described in detail by means of cluster gas aggregation source. Basic characterization of the films is performed using transmission electron microscopy, ultraviolet-visible and Fourier-transform infrared spectroscopies. It is shown that the morphology, structure and optical properties of such prepared nanocomposites differ significantly from the ones fabricated by means of magnetron sputtering of Ag target in Ar/n-hexane mixture.     

Characterization of photoactive polymer thin films using transmission spectrum

There are many different methods applied to obtain the optical constants of thin films using transmission spectrum, none of them applied to photoactive polymer thin films. The aim of this work is to find the suitable method for routine measurements of photoactive polymer thin films. In order to achieve this goal, different methods are applied to simulated thin films of known optical constants to compare their accuracies, hence choosing the most suitable method for studying the photoactive polymer thin films. It is found that the fitting methods are not suitable for photoactive polymer thin films while numerical solution of two independent transmission measurements is suitable for such films, so poly methy1 methacrylate (PMMA) films doped with different concentrations of photoactive unit Disperse Red 1 (DSR1) are characterized using this method. The refractive index of PMMA doped with 0.2% of DSR1 (1 g PMMA, 2 mg DSR1) is found to be 1.534 with error 0.656% at λ = 630 nm. It is also found that the refractive index of photoactive polymer thin films increases linearly with increasing photoactive unit up to concentration 0.25%.     

Investigation of the solution condition of lithium electrolyte solutions with LiCF3SO3 salt

Solution condition of the lithium electrolyte of LiCF₃SO₃ salt dissolved in propylene carbonate (PC), dimethoxyethane (DME) and tetrahydrofuran (THF) were investigated based on the measurements of the self-diffusion coefficients of lithium (D_Li) and anion (D_F) species using the pulsed-field gradient (PFG) NMR, viscosity and conductivity. D_Li and D_F decreased with the increase in the solution concentration for these electrolytes. This result reflects the change in the dissociation degree of the salt and the viscosity depending on the solution concentration. In the case of PC solution (the dielectric constant () of PC: 65), measured D_Li and D_F were separated each other with the decrease in the concentration because the dissociation of the salt was promoted to increase the content of dissociated ions. With an increase in the concentration, the dissociation would be restricted and D_Li and D_F approximated each other, which means that the associated ion pairs are dominant in the solution. The effective ionic radius (r_eff) of cation species of PC solution estimated from the Stokes-Einstein relation using the diffusion coefficient and the viscosity results was four times greater than that of the naked lithium ion and independent of the dissociation degree. On the other hand, the r_eff of anion species changed depending on the dissociation degree. This suggests that the dissociated lithium ions are solvated by the PC solvent in the solution. DME and THF solutions did not show the solvation effect from the result of the change in r_eff with the concentration. This suggests that the dissociation degree of the dissolved salt was low due to the low of their solvents ( 7.2) and the ion pairs would dominant in the solutions independent of the solution concentration.     

Characterization of polymer films using a slow positron beam

Polymer structures have been investigated using positron annihilation lifetime spectroscopy (PALS) with a slow positron beam as well as a conventional radioactive source (²²Na). The properties of the free volume holes near the polymer surface were studied as a function of the positron implantation energy. The longest lifetime was associated with ortho-positronium (o-Ps) annihilation in the free volume holes. In polytetrafluoroethylene film, the lifetime of o-Ps was observed to decrease with increasing positron implantation depth, and a significant change in the o-Ps lifetime was found at a short distance (about 10 nm) from the surface, while its intensity increased. This result implies that near the polymer surface the free volume holes become larger that in the bulk. The effect of temperature on the polymer sub-surface layers was also studied. For high molecular weight polystyrene, the glass transition temperature for the sub-surface was lower than that for the bulk and thermal expansion coefficient of the sub-surface layers was found to be larger than the bulk value. Electronic Publication     

BaTiO3填充PEO基复合聚合物电解质厚膜的制备与性能研究

采用溶液铸膜法制备PEO基复合聚合物电解质(CPE)厚膜,利用XRD、SEM、DSC、FTIR分析等多种结构测量技术对CPE的性能进行了表征和分析.本文研究的是在(PEO)6:NaPO3基导电聚合物电解质中加入质量分数为3～10 wt％ BaTiO3填料,从而分析性能的变化.(PEO)6:NaPO3在加入填料后玻璃化转...     

Structural features and gas tightness of EB-PVD 1Ce10ScSZ electrolyte films

The structure of Ceria doped Scandia Stabilized Zirconia (1Ce10ScSZ) electrolyte film deposited by EB-PVD (Electron Beam-Physical Vapour Deposition) technique on NiO-ZrO₂ substrate was characterized by electron microscopy. The highly porous substrate was densely covered by deposited film without any spallation. The produced electrolyte layer was of a columnar structure with bushes, bundles of a diameter up to 30 ??m and diverse height. Between the columns, delamination cracks of few microns length were visible. The annealing of zirconia film at 1000 °C resulted in its densification. The columnar grains and delaminating cracks changed their shape into a bit rounded. High magnification studies revealed nanopores 5?C60 nm formed along the boundaries of the columnar grains during annealing. High-quality contacts between the electrolyte film and anode substrate ensured good conductivity of the electrolyte film and high efficiency of SOFC.     

The effect of fumed silica in the polymer gel electrolyte on the cycle efficiency of lithium deposition/striping process

Polymer gel electrolyte with addition of fumed silica was prepared by the UV polymerization of methyl methacrylate, oligomer of ethyl glycol dimethacrylate and liquid electrolyte. The effect of fumed silica on the cycle efficiency of lithium deposition/striping at stainless steel (SS) electrode was researched by cyclic voltammetry (CV), FTIR and electrochemical AC impedance. The addition of fumed silica in the polymer gel electrolyte can enhance the retention ability of liquid electrolyte and it can trap impurities in the polymer gel electrolyte. The silica is interactive with carbonyl group (C=O) of the solvent and polymer matrix. All of them are beneficial to the cyclic efficiency of lithium deposition/striping at SS electrolyte, which is confirmed in the CV.     

Studies on structural,electrical and dielectric properties of nickel ion conducting polyvinyl alcohol based polymer electrolyte films

Polyvinyl alcohol (PVA) complexed with different weight percent ratios of Nickel Bromide (NiBr₂) salt were prepared by using solution cast technique. X-ray diffraction analysis confirmed the complexation of the salt with the polymer. Differential scanning calorimetry was used to determine the glass transition and melting temperatures of pure PVA and PVA:NiBr₂ complexed films. Electrical conductivity was measured using ac impedance analyzer in the frequency and temperature range 1 Hz–1 MHz and 303–373 K respectively. It was observed that the magnitude of electrical conductivity increases with NiBr₂ salt concentration as well as temperature. Frequency dependence electrical conductivity of the complexed polymer electrolyte films follows the Jonscher’s equation. The dielectric behavior was analyzed using dielectric permittivity\(\left( {{\varepsilon ^\prime}} \right)\) and loss tangent \(\left( {\tan \delta } \right)\) of the samples. Relaxation time was determined from the variation of loss tangent with frequency at different temperatures. The modulus spectra indicated the non-Debye nature of the material.     

Preparation and photochromic behavior of crosslinked polymer thin films containing polyoxometalates

A series of reversible photochromic nanocomposite films were prepared by entrapping phosphotungstic acid (PWA) and molybdenumphsophoric acid (PMoA) into P(VP-BVA), which was a crosslinked polymer based on N-vinylpyrrolidone (VP) and bisvinyl-A (BVA). The microstructure, photochromic behavior and mechanism of the films were studied with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectra (UV-vis) and electron resonance spectra (ESR). The TEM image showed that the polyoxometalates particles had regular microstructure with narrow size distribution (average diameter of 30 nm) in hybrid films. FT-IR results showed that the Keggin geometry of polyoxometalates (POM) was still preserved inside the composites and strong coulombic interaction between POM and crosslinked polymer matrix was built. Irradiated with ultraviolet light, the transparent films changed from colorless to blue and showed reversible photochromism. Oxygen plays an important role during the bleaching process. PMoA/P(VP-BVA) film had higher photochromic efficiency and slower bleaching reaction than PWA/P(VP-BVA) film. The characteristic signals of W (V) or Mo (V) in ESR spectra indicated that electron transfer occurred between the organic substrates and heteropolyanions under UV irradiation, which induced heteropolyanions to heteropolybules with simultaneous oxidation of the organic substrates.     

An experimental examination of thin films of lithium phosphorus oxynitride (a solid electrolyte)

The results of examination of thin-film samples of the LiPON solid electrolyte, which were synthesized by magnetron sputtering, are reported. Data on the morphology, structure, elemental and phase composition, and electrophysical parameters of LiPON films are presented.     

Characterization of spray-coating methods for conjugated polymer blend thin films

We examine the characteristics and functionality of conjugated polymer thin films, based on blends of poly(9,9-dioctylfluorene-2,7-diyl-co-bis-N,NN′-(4-butylphenyl)-bis-N,N′-phenyl-1,4-phenylenediamine) (PFB) and poly(9,9-dioctylfluorene-2,7-diyl-co-benzothiadiazole) (F8BT), using a spray-coating deposition technique suitable for large areas. The morphological properties of these blend films are studied in detail by atomic force microscopy (AFM) methods, showing that favourable results, in terms of layer deposition rate and uniformity, can be achieved using a 5:1 blend of o-dichlorobenzene and chlorobenzene as the solvent medium. A photoluminescence quenching efficiency of above 80 % is also observed in such blend films. As a feasibility study, prototypical photovoltaic devices exhibit open circuit voltages of up to 1.0 V under testing, and solar power conversion efficiencies in the 0.1–1 % order of magnitude; metrics which are comparable with those reported for spin-coated cells of the same active blend and device architecture.     

Preparation and study of conductivity in lithium salt complexes of mixed MEEP : PEO polymer electrolytes

Poly(ethylene oxide)-LiX complexes and poly[bis(methoxy ethoxy ethoxide) phosphazene]-LiX complexes of polymer thin films were prepared. Conductivity measurements were carried out and the values were found to lie between 10⁻⁸ and 1.7 × 10⁻⁵ (S/cm). MEEP : LiX salts showed higher conductivity than PEO-LiX salts despite lower dimensional stability. For enhancing stability and conductivity, MEEP-PEO : (LiX) _n systems were prepared and conductivity measurements carried out. Further the MEEP/PEO : (LiX) _n was doped with Al₂O₃ and TiO₂ nanocomposite ceramic fillers and the conductivity was studied. The conductivity vs temperature plots showed the enhancement of conductivity with TiO₂ added nanocomposite ceramic fillers. The enhanced conductivity is explained on the basis of the effect of local structural modification—promoting localized amorphous region—for enhancement of the Li⁺ ion transport.