Ionic conductivity of solid polymer electrolytes for dye‐sensitized solar cells

We developed an ionic conductivity model of solid polymer electrolytes for dye‐sensitized solar cells (DSSCs) based on the Nernst–Einstein equation in which the diffusion coefficient is derived from the molecular thermodynamic model. We introduced concentration‐dependence of the diffusion coefficient into the model, and the diffusion coefficient was expressed by differentiating the chemical potential by concentration. The ionic conductivities of polymer electrolytes (PEO/LiI/I₂ system) were investigated at various temperatures and compositions. We prepared a set of PEO in which an EO : LiI mole ratio of 10 : 1 was kept constant for PEO·LiI·(I₂)_n compositions with n = 0.02, 0.05, 0.1, 0.15, 0.2, and 0.3 (mole ratio of LiI : I₂). The ionic conductivities of the electrolytes were measured using a stainless steel/polymer‐electrolyte/stainless steel sandwich‐type electrode structure using alternating current impedance analysis. The values calculated using the proposed model agree well with experimental data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Characterization of PEO-PAN hybrid solid polymer electrolytes

Hybrid solid polymer electrolytes (HSPE) of high ionic conductivity were prepared using polyethylene oxide (PEO), polyacrylonitrile (PAN), propylene carbonate (PrC), ethylene carbonate (EC), and LiClO₄. These electrolyte films were dry, free standing, and dimensionally stable. The HSPE films were characterized by constructing symmetrical cells containing nonblocking lithium electrodes as well as blocking stainless steel electrodes. Studies were made on ionic conductivity, electrochemical reaction, interfacial stability, and morphology of the films using alternating current impedance spectroscopy, infrared spectroscopy, and scanning electron microscopy. The properties of HSPE were compared with the films prepared using (i) PEO, PrC, and LiClO₄; and (ii) PAN, PrC, EC, and LiClO₄. The specific conductivity of the HSPE films was marginally less. Nevertheless, the dimensional stability was much superior. The interfacial stability of lithium was similar in the three electrolyte films. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2191–2199, 1997     

Preparation and ionic conductivity of solid polymer electrolyte based on polyacrylonitrile‐polyethylene oxide

The transparent and flexible solid polymer electrolytes (SPEs) were fabricated from polyacrylonitrile‐polyethylene oxide (PAN‐PEO) copolymer which was synthesized by methacrylate‐headed PEO macromonomer and acrylonitrile. The formation of copolymer is confirmed by Fourier‐transform infrared spectroscopy (FTIR) measurements. The ionic conductivity was measured by alternating current (AC) impedance spectroscopy. Ionic conductivity of PAN‐PEO‐LiClO₄ complexes was investigated with various salt concentration, temperatures and molecular weight of PEO (Mn). And the maximum ionic conductivity at room temperature was measured to be 3.54 × 10^?4 S/cm with an [Li⁺]/[EO] mole ratio of about 0.1. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 461–464, 2006     

Ionic conductivity and physical stability study of gel nework polymer electrolytes

Gel polymer electrolytes (GPE) were prepared by a crosslinking reaction between poly(ethylene glycol) and a crosslinking agent with three isocyanate groups in the presence of propylene carbonate (PC) and ethylene carbonate (EC) or their mixture, and their ionic conducting behavior was carefully investigated. When the plasticizer amount was fixed, the ionic conductivity was greatly influenced by the nature of plasticizers. It was found that the conductivity data followed the Arrhenius equation in the GPE. Whatever plasticizer was used, a maximum ambient conductivity was found at a salt concentration near [Li⁺]/[EO] equal to 0.20. The physical stability of GPE was studied qualitatively by weight loss of GPE under pressure. It was shown that the stability was greatly affected by the network structure of the GPE and the most stable one in our research was the GPE containing the PEO₁₀₀₀ segment, which has a strong interaction between network and plasticizers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2957–2962, 2000     

Effect of ethylene carbonate on properties of PVP-CsAlO2-LiClO4 solid polymer electrolytes

ABSTRACT

Solid polymer electrolytes (SPEs) have been widely studied due to its extensive applications in high energy rechargeable batteries, supercapacitors, fuel cells, photoelectrochemical and electrochromic displays. Herein, SPEs based on polyvinyl pyrrolidone (PVP) doped with cesium aluminate (CsAlO₂) nanoparticles (NPs), lithium perchlorate (LiClO₄) as an electrolyte and varying amounts viz., 2, 4, 6 and 8 wt.% of ethylene carbonate (EC) as plasticizer have been fabricated by solution intercalation technique. The structural features of PVP-CsAlO₂-LiClO₄-EC SPEs have been studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The morphology of PVP-CsAlO₂-LiClO₄-EC SPEs has been examined by scanning electron microscopy (SEM). The thermal properties of the SPEs were characterized by the thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC) techniques. The TGA and DSC results revealed that a significant reduction in thermal stability and glass transition temperature (T_g) of PVP with an increase in EC content in SPE films. The optoelectrical properties of PVP-CsAlO₂-LiClO₄-EC SPE films have been evaluated using UV–visible spectroscopy. The band gap energy (E_g) was found to decrease with an increase in EC content, exhibiting a minimum of 4.23 eV for PVP-8 wt.% CsAlO₂-15 wt.% LiClO₄-8 wt.% EC. This could be ascribed to the formation of localized states and increased degree of disorder in the PVP-CsAlO₂-LiClO₄ SPE films. The integrated plasticizers increase the values of refractive index (RI), optical conductivity, and dielectric constants of PVP-CsAlO₂-LiClO₄ SPE films. The AC conductivity of the SPEs has been evaluated at room temperature using digital LCR meter in the frequency range 100 Hz – 5 MHz. The conductivity strongly depends on CsAlO₂ NPs and EC plasticizer content in SPEs.     

Crystallinity,thermal properties,morphology and conductivity of quaternary plasticized PEO‐based polymer electrolytes

Quaternary plasticized solid polymer electrolyte (SPE) films composed of poly(ethylene oxide), LiClO₄, Li_1.3Al_0.3Ti_1.7(PO₄)₃, and either ethylene carbonate or propylene carbonate as plasticizer (over a range of 10–40 wt%) were prepared by a solution‐cast technique. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) indicated that components such as LiClO₄ and Li_1.3Al_0.3Ti_1.7(PO₄)₃ and the plasticizers exerted important effects on the plasticized quaternary SPE systems. XRD analysis revealed the influence from each component on the crystalline phase. DSC results demonstrated the greater flexibility of the polymer chains, which favored ionic conduction. SEM examination revealed the smooth and homogeneous surface morphology of the plasticized polymer electrolyte films. EIS suggested that the temperature dependence of the films' ionic conductivity obeyed the Vogel–Tamman–Fulcher (VTF) relation, and that the segmental movement of the polymer chains was closely related to ionic conduction with increasing temperature. The pre‐exponential factor and pseudo activation energy both increased with increasing plasticizer content and were maximized at 40 wt% plasticizer content. The charge transport in all polymer electrolyte films was predominantly reliant on lithium ions. All transference numbers were less than 0.5. Copyright © 2006 Society of Chemical Industry     

Ionic conductivity enhancement of the plasticized PMMA/LiClO4 polymer nanocomposite electrolyte containing clay

This work has demonstrated that the addition of an optimum content of dimethyldioctadecylammonium chloride (DDAC)-modified montmorillonite clay (Dclay) enhances the ionic conductivity of the plasticized poly(methyl methacrylate)-based electrolyte by nearly 40 times higher than the plain system. Specific interactions among silicate layer, carbonyl group (CO) and lithium cation have been investigated using Fourier-transform infrared (FTIR), solid-state NMR, alternating current impedance. The FTIR characterization confirms that both of the relative fractions of ‘complexed’ CO sites and ‘free’ anions increase with the increase of the Dclay content, indicating that strong interaction exists between the CO group and the lithium salt. In addition, the solid-state NMR demonstrates that the interaction between the PMMA and the clay mineral is insignificant. The addition of clay mineral promotes the dissociation of the lithium salt and thus, the specific interaction can be enhanced between the CO and the free lithium cation. However, the balanced attractive forces among silicate layers, CO groups, lithium cations and anions is critical to result in the higher ionic conductivity.     

单离子型全氟凝胶聚合物固体电解质的结构与离子导电性能

从Nafion树脂出发,制备了一系列单离子型全氟凝胶聚合物固体电解质膜,其中有机极性介质为碳酸丙烯酯(PC)。通过溶胀曲线测定、红外光谱分析、复阻抗分析等手段对材料的结构与离子导电性能进行了研究。结果表明,PC与阳离子之间存在较强的相互作用,而且PC与Li+离子之间的相互作用强于PC与H+离子之间的相互作用。PC含量对材料的离子导电性能也有较大的影响。随着PC含量的增加,材料的离子电导率呈上升趋势。当PC含量较低时,Li+型样品的室温离子电导率高于H+型样品;而PC含量较高时,Li+型样品的室温离子电导率则低于H+型样品。Li+型样品和H+型样品的室温离子电导率均可达到1.25×10-4S·cm-1。     

PVDF-HFP型凝胶聚合物固体电解质的结构与离子导电性能

以PVDF-HFP为基体聚合物，制备了一系列凝胶聚合物固体电解质膜，其中有机极性介质为碳酸丙烯酯(PC)，电解质盐为LiClO4。通过红外光谱分析、差示扫描量热分析、复阻抗分析等手段对凝胶聚合物固体电解质的结构与离子导电性能进行了研究。结果表明，PC与阳离子之间存在较强的络合作用，PC对基体聚合物有很强的增塑作用。锂盐和PC含量对材料的离子导电性能有较大的影响。随着锂盐和PC含量的增加，材料的离子电导率呈上升趋势。     

Ionic conductivities of solid polymer electrolyte/salt systems for lithium secondary battery

We establish a new ionic conductivity model based on the Nernst-Einstein equation in which the diffusion coefficient is derived from modified double lattice-nonrandom-Pitzer-Debye-Hückel (MDL-NR-PDH) model. The proposed model takes into account the mobility of the salt and the motion of the polymer host simultaneously by expressing the effective chemical potential as the sum of chemical potentials of the salt and the polymer. To describe the segmental motion of the polymer chain, which is the well-known conduction mechanism for solid polymer electrolyte (SPE) systems, the effective co-ordinated unit parameter is introduced. The obtained co-ordinated unit parameter for each state is used to describe the behavior of the ionic conductivities of the given systems. Good agreement is obtained upon comparison with experimental data of various PEO and salt systems in the interested ranges.     

Preparation and characterization of a solid polymer electrolyte PEO‐ENR50 (80/20)‐LiCF3SO3

The preparation and characterization of a polymer electrolyte films containing 80 wt % of poly (ethylene oxide) (PEO) and 20 wt % epoxidized natural rubber (ENR50) complexed with LiCF₃SO₃ has been reported. The ac impedance data showed good conducting properties of the solid polymer electrolyte (SPE) films. The greatest room temperature ionic conductivity of 7.5 × 10^?5 S cm^?1 was obtained at 25 wt % of LiCF₃SO₃ salt. This result has been supported by differential scanning calorimeter and X‐ray diffraction analysis. Analysis differential scanning calorimetry showed the relative percentage of crystallinity and T_m of PEO decreased with the increasing wt % of LiCF₃SO₃. Analysis with X‐ray diffraction suggested that the semicrystalline nature of PEO turned to amorphous due to the presence of LiCF₃SO₃. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

全固态聚合物电解质的性能研究

聚合物电解质由于本身的优点,已成为锂离子电池研究的一个热点.聚合物电解质由聚合物、锂盐及添加剂组成,本文综述了聚合物电解质研究的新体系,论述了聚合物电解质中各组分对其性能的影响.     

Fabrication and characterization of a solid polymeric electrolyte of PAN‐TiO2‐LiClO4

The ionic conductivity of PAN‐TiO₂‐LiClO₄ as a function of TiO₂ concentration and temperature has been reported. The electrolyte samples were prepared by solution casting technique. Their conductivity was measured using the impedance spectroscopy technique. The highest room temperature conductivity of 1.8 × 10^?4 S cm^?1 was obtained at 7.5 wt % of TiO₂ filler. It was observed that the relationship between temperature and conductivity were linear, fitting well in Arrhenius and not in Vogel‐Tamman‐Fulcher equation. The pre‐exponential factor, σ₀ and E_a are 1.8 × 10^?4 S cm^?1 and 0.15 eV, respectively. The conductivity data have been supported by differential scanning calorimeter (DSC) analysis. DSC analysis showed that there was a significant change in glass transition temperature (T_g) with the filler concentration. The SEM micrograph revealed that the TiO₂ particles are dispersed in the electrolyte, thus enhancing its conductivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nanocomposite polymer electrolyte comprising PEO/LiClO4 and solid super acid: effect of sulphated-zirconia on the crystallization kinetics of PEO

A novel PEO-based nanocomposite polymer electrolyte is prepared by using solid super acid sulphated-zirconia (, SZ) as the filler. Polarized optical microscopy (POM) and differential scanning calorimeter (DSC) results show that part of SZ particles may act as the nucleus of PEO spherulites and thus increase the amount of PEO spherulites. On the other hand, other SZ particles, which do not act as the nucleus, can restrain the recrystallization tendency of PEO chains through Lewis acid-base interaction and hence decrease the growth speed of PEO spherulites. As a result, the PEO component in PEO-LiClO₄-SZ can maintain a high amorphous state for a long time. The room temperature ionic conductivity of PEO-LiClO₄-SZ is relative high and stable compared with pristine PEO-LiClO₄, indicating that it is promising for all solid-state rechargeable lithium ion batteries.     

苯酐改性聚乙二醇型聚氨酯固态电解质的制备与性能

以异佛尔酮二异氰酸酯（IPDI）、聚对苯二甲酸-3-甲基-1,5-戊二醇酯二醇（TPA-1000）、聚乙二醇（PEG-2000）、一缩二乙二醇（DEG）为主要原料合成了一系列热塑型聚氨酯弹性体,然后加入20%的锂盐（LiTFSI）制备不同的全固态电解质（SPE）。结果表明,随着TPA-1000含量的减少和PEG-2000含量的增加,SPE的耐热性增加,玻璃化转变温度减小,拉伸强度减小,断裂伸长率增加。SPE的离子电导率与温度的关系基本符合Arrhenius方程,在80℃,SPE（除纯PEG-2000的电解质外）的电化学窗口均达到4.0V以上,其中质量比TPA-1000：PEG-2000=1：2（SPE4）综合性能最佳,力学为1.87Mpa、电导率为2.15?10-4 S cm-1、窗口为4.3V。以SPE4组装的全固态电池在80℃、0.2C下放电比容量为150 mAh/g。     

Application of liquid gel polymer electrolyte based on chitosan–NH4NO3 for proton batteries

Liquid gel polymer electrolyte (LGPE) based on chitosan, ammonium nitrate, and acetic acid with a ratio of 1.9 : 0.17 : 96.3 wt % gives the highest conductivity of (1.46 ± 0.07) ´ 10⁻¹ S cm⁻¹ at room temperature. This optimized composition of electrolyte is then used in proton batteries with the configuration of Zn + ZnSO₄·H₂O/LGPE/MnO₂. The open circuit voltage of battery is 1.41 V during 48 h of storage. The battery obtained a discharge capacity of 27.90 mA h⁻¹ upon discharge at 1.0 mA current. The maximum power density for the battery is 3.67 mW cm⁻². © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A novel polymer electrolyte based on polydioxolane polyurethane with Na+ single‐ionic conductivity

A series of novel polyurethane ionomers with polydioxolane (PDXL) as soft segment was prepared and characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis. The ionomers obtained were Na⁺ single‐ionic conductors. Their ionic conductivity and water absorption were tested. At medium temperature (> 75°C), the conductivity of ∼ 10⁻⁵ s cm⁻¹ was reached. The temperature dependence of conductivity could not be well expressed by both Arrhenius and VTF equations. When ionization level was fixed, the conductivity increased as the Mn of PDXL decreased. We also discussed the effect of ionization level on water absorption. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1711–1719, 1999     

PVdF-HFP/P123 hybrid with mesopores: a new matrix for high-conducting, low-leakage porous polymer electrolyte

Highly conducting porous polymer electrolytes comprised of poly(vinylidene-fluoride-co-hexafluoropropylene) (PVdF-HFP), polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (P123), ethylene carbonate (EC), propylene carbonate (PC), and LiClO₄ were fabricated. The PVdF-HFP/P123 hybrid polymer membranes were made with a phase inverse method and the electrolyte solution uptake was carried out in glove box to avoid the moisture contamination. It was found that when a small amount of polymer surfactant (P123) was blended into the PVdF-HFP, mesopores with well-defined sizes were formed. Impedance spectroscopy showed that the room temperature conductivity of (PVdF-HFP)/P123 polymer electrolytes increased as the content of P123 increased up to 4×10⁻³ S/cm. Nitrogen adsorption isotherms, electrolyte solution uptake, porosity measurements, and SEM micrographs showed that the enhanced conductivity was due to increase the pore volume, pore density, and electrolyte uptake. The highest conduction was found when the weight ratio of P123 to PVdF-HFP was 70%, when big channels were formed in the hybrid polymer membrane. Furthermore, blending P123 in PVDF-HFP reduced the pore size of polymer membrane, therefore, the solution leakage was also reduced. These polymer electrolytes were stable up to 4.5 V (vs Li/Li⁺) and the performance of the model lithium ion battery made by sandwiching the polymer electrolyte between a LiCoO₂ anode and a MCMB cathode, showed great promise for the use of these polymer electrolytes in lithium ion batteries.     

Studies of solvent effect on the conductivity of 2‐mercaptopyridine‐doped solid polymer blend electrolytes and its application in dye‐sensitized solar cells

Solvents and electrolytes play an important role in the fabrication of dye‐sensitized solar cells (DSSCs). We have studied the poly(ethylene oxide)‐poly(methyl methacrylate)‐KI‐I₂ (PEO‐PMMA‐KI‐I₂) polymer blend electrolytes prepared with different wt % of the 2‐mercaptopyridine by solution casting method. The polymer electrolyte films were characterized by the FTIR, X‐ray diffraction, electrochemical impedance and dielectric studies. FTIR spectra revealed complex formation between the PEO‐PMMA‐KI‐I₂ and 2‐mercaptopyrindine. Ionic conductivity data revealed that 30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂ electrolyte can show higher conductivity (1.55 × 10^?5 S cm^?1) than the other compositions (20, 40, and 50%). The effect of solvent on the conductivity and dielectric of solid polymer electrolytes was studied for the best composition (30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂) electrolyte using various organic solvents such as acetonitrile, N,N‐dimethylformamide, 2‐butanone, chlorobenzene, dimethylsulfoxide, and isopropanol. We found that ac‐conductivity and dielectric constant are higher for the polymer electrolytes processed from N,N‐dimethylformamide. This observation revealed that the conductivity of the solid polymer electrolytes is dependent on the solvent used for processing and the dielectric constant of the film. The photo‐conversion efficiency of dye‐sensitized solar cells fabricated using the optimized polymer electrolytes was 3.0% under an illumination of 100 mW cm^?2. The study suggests that N,N‐dimethylformamide is a good solvent for the polymer electrolyte processing due to higher ac‐conductivity beneficial for the electrochemical device applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42489.