A series of LiI/acetamide phase transition electrolytes and their applications in dye-sensitized solar cells

A new series of electrolytes composed of LiI and acetamide have been investigated in dye-sensitized solar cells (DSSCs). These electrolytes melt at about 50 °C and their ionic conductivities vary drastically below and above the melting points (T_m). They tend to form large crystals at low temperature, leading to poor penetration and contact within porous TiO₂ anode film. This shortage is improved by introducing nano-SiO₂ particles into the electrolyte. A total conversion efficiencies (η) of 0.3% at 35 °C and 4.2% at 75 °C are achieved respectively under AM 1.5 simulated solar light illumination when a LiI/acetamide (1:16) electrolyte with 8 wt% nano-SiO₂ is used. It is expected that the DSSC using phase transition electrolyte could show high efficiency for operation at high temperature and high stability for storage at low temperature.     

AUGMENTATION OF PHOTOCATALYTIC ACTIVITY OF TiO2 THIN FILMS PREPARED BY A SOL-GEL TECHNIQUE

In order to increase the photocatalytic activity on TiO₂ thin film per its external surface area, the structure of flat thin film was modified by adding a small amount of polyethylene glycol (PEG) to TiO₂ sol solution. By firing PEG contained in a TiO₂ gel film, a porous structure was developed. The photocatalytic activities of the thin films prepared thus were evaluated by the degradation of 2-propanol in the aqueous solutions under black light illumination. The photocatalytic activity of TiO₂ thin film prepared with added PEG 400 by 2.6 wt% or PEG 2000 by 9.5 wt% was increased by about 30% as compared to that prepared without added PEG.     

Characteristics of PVdF-HFP/TiO2 composite membrane electrolytes prepared by phase inversion and conventional casting methods

Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer membranes filled with various contents of titania (TiO₂) nanocrystalline particles are prepared by phase inversion technique and, along with conventional casting method for comparison. N-methyl-2-pyrrolidone (NMP) as a solvent is used to dissolve the polymer and to make the slurry with TiO₂. Cast film is obtained by spreading the slurry and evaporating NMP in a dry oven, while phase inversion membrane by promptly immersing the spread slurry into flowing water as a non-solvent. Physical and electrochemical characterizations, such as morphology, thermal and crystalline behavior, and other transport properties of lithium ionic species, are carried out for the polymer films/membranes and the polymer electrolytes with absorbing an electrolyte solution. Phase inversion polymer electrolytes are proved to show superior behaviors in electrochemical properties, such as ionic conductivity, electrochemical and interfacial stability, than cast film electrolytes. This is greatly owed to highly porous structure of phase inversion membranes. Even including the feature of interfacial resistance with lithium electrode, phase inversion polymer electrolytes of PVdF-HFP/(5-20 wt.% TiO₂) can be optimized as the adequate ones in applying to the electrolyte medium of lithium rechargeable batteries.     

Environmental Friendly, Low Cost Quasi Solid State Dye Sensitized Solar Cell: Polymer Electrolyte Introduction

The most efficient DSSCs reported till date contains liquid electrolytes with I^?/I^3? redox couple. However, the disadvantages of liquid electrolytes lead to reduce the impact of DSSCs. In the present work, the I^?/I^3? liquid electrolyte was replaced by quasi-solid gel polymer electrolytes (GPEs) using polyethylene glycol (M_wt = 20,000), which are incorporated in small fractions (0, 1, 5, 10, 15 and 20 % w/v) into the liquid iodine/iodide electrolyte matrix. The roughness and homogeneity of the GPEs on the surface of the TiO₂ electrodes was monitored by atomic force microscope which indicates the physical cross linking of polymer chains in a gel network. The conductivity (σ) and the thermal stability (TGA) of the GPEs compared with the liquid electrolyte were studied in details. The photovoltaic characteristics [V_oc, I_sc, fill factor and efficiency (η)] of the DSSCs based GPEs were recorded, The results revealed the DSSCs assembled with the gel polymer electrolyte reports a higher short circuit density (J_SC) and lower or similar open circuit voltage (V_OC) than the cells with liquid electrolyte. The overall light-to-electrical-energy conversion efficiencies (η) of the cells based GPEs showed a relatively higher stability over a period of time compared with those based liquid electrolyte, indicating that the quasi-solid nature of the GPEs may impart flexibility to DSSCs so that some large-scale productions such as roll-to-roll process can be realized.     

An imidazolium iodide–containing hyperbranched polymer ionic liquid that improves the performance of dye-sensitized solar cells

In this study, we synthesized an imidazolium iodide–containing hyperbranched polymer ionic liquid (HPIL) for use as the gel electrolyte of dye-sensitized solar cells (DSSCs). We incorporated HPIL at various contents (4, 8, and 15 wt%) in a solvent-free ionic liquid (1-propyl-2,3-dimethylimidazolium iodide and 1-ethyl-3-methylimidazolium tetrafluoroborate)–based quasi-solid gel electrolyte (IL-A) and a solvent (3-methoxypropionitrile)-based fluid gel electrolyte (IL-B). After fabricating N719 dye–based DSSCs incorporating the HPIL/IL-A and HPIL/IL-B gel electrolytes, we recorded the electrochemical impedance spectra and measured the photovoltaic (PV) performance of these devices. In the dark, the DSSCs incorporating HPIL exhibited higher charge recombination resistances at the interface between TiO₂/dye and the electrolyte. This high recombination resistance suppressed the dark current and improved the PV performance of the devices incorporating HPIL. The DSSCs fabricated from the HPIL/IL-B gel electrolyte displayed higher photo-conversion efficiency, while those fabricated from the HPIL/IL-A gel electrolyte provided superior operational stability. Under AM 1.5 illumination (100 mW cm^?2), we measured a photo-conversion efficiency of 7.18 %, a short-circuit current density of 16.09 mA cm^?2, an open-circuit voltage of 0.69 V, and a fill factor of 0.65 for the DSSC incorporating the gel electrolyte HPIL/IL-B (4:96, w/w). The DSSC incorporating the gel electrolyte HPIL/IL-A (15:85, w/w) exhibited good operational stability, retaining approximately 93 % of its original efficiency after 500 h.

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Graphical abstract An imidazolium iodide-containing hyperbranched polymer ionic liquid HPIL was synthesized for use as the gel electrolyte of dye-sensitized solar cells.

     

Optimization of the dye-sensitized solar cell performance by mechanical compression

In this study, the P25 titanium dioxide (TiO₂) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO₂ NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO₂ inter-particle distance improving the electron transport efficiency. The UV–vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO₂ NP thin film compressed at pressure of 279 kg/cm², the minimum resistance of 9.38 Ω at dye/TiO₂ NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm², and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO₂ NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized.     

Dye-sensitized solar cells based on double-layered TiO2 composite films and enhanced photovoltaic performance

Dye-sensitized solar cells (DSSCs) are fabricated based on double-layered composite films of TiO₂ nanoparticles and hollow spheres. The photoelectric conversion performances of DSSCs based on nanoparticles/nanoparticles (PP), hollow spheres/hollow spheres (HH), hollow spheres/nanoparticles (HP), and nanoparticles/hollow spheres (PH) double-layered films are investigated, and their photo-electric conversion efficiencies are 4.33, 4.72, 4.93 and 5.28%, respectively. The enhanced performance of TiO₂ nanoparticles/hollow spheres double-layered composite film solar cells can be attributed to the combined effect of following factors. The light scattering of overlayer hollow spheres enhances harvesting light of the DSSCs and the underlayer TiO₂ nanoparticle layer ensures good electronic contact between film electrode and the F-doped tin oxide (FTO) glass substrate. Furthermore, the high surface areas and pore volume of TiO₂ hollow spheres are respectively beneficial to adsorption of dye molecules and transfer of electrolyte solution.     

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.     

Novel cyclic sulfonium iodide containing siloxane high performance electrolyte for dye-sensitized solar cell

A new type of solid and gel state electrolytes based on siloxane cyclic sulfonium iodides was synthesized and used in dye-sensitized solar cells. The resulting electrolytes were characterized by ¹H NMR, TGA, diffusion coefficient, and ion conductivity. The thermo-oxidative stabilities of the prepared ionic species are lower than that of DMII because the bond strength of S⁺–C in thiophenium is lower than that of N⁺–C in imidazolium. Among the three SiCSIs based electrolytes, SiCSI3 showed a maximum photo-conversion efficiency of 7.3%. In addition, the performance of the DSSCs showed relatively reasonable compared with the imidazolium type DMII electrolyte.     

Symmetric electric double-layer capacitor containing imidazolium ionic liquid-based solid polymer electrolyte: Effect of TiO2 and ZnO nanoparticles on electrochemical behavior

Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF–HFP)-based polymer electrolytes embedded with 1-ethyl-3-methylimidazolium tetrafluoroborate ioniliquid have been synthesized to improve the ionic conductivity. Electric double-layer capacitors (EDLC) have been prepared using the synthesized polymer electrolytes. Inorganic oxide fillers (5 wt %) such as titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles have been added to polymer electrolytes to compare the electrochemical behavior of the fabricated EDLC. The intrinsic dielectric constant of nanoparticles contributes in ionic dissociation which enhances ionic conductivity of electrolytes and also controls the specific capacitance of the EDLC fabricated with these electrolytes. Physicochemical properties of polymer nanocomposites have been investigated using X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analysis, which confirms decrease of crystalline phase in host polymer PVDF–HFP. The maximum voltage stability is obtained for TiO₂-based polymer electrolyte. The high specific capacitance as well as high energy density is obtained for the EDLC cell with TiO₂-based polymer electrolyte compared to EDLC with ZnO nanoparticles-based electrolyte. EDLC cells show specific capacitance of 76.4 and 44.51% of initial specific capacitance value at 2000th cycle for ZnO and TiO₂-based polymer electrolytes, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48757.     

Self-organized TiO2 nanotubes in mixed organic–inorganic electrolytes and their photoelectrochemical performance

The formation of self-organized TiO₂ nanotube array films by electrochemical anodizing titanium foils was investigated in a developed organic–inorganic mixed electrolyte. It was found that the structure and morphology of the TiO₂ nanotube layer were greatly dependent upon the electrolyte composition, anodizing potential and time. Under the optimized electrolyte composition and electrochemical conditions, a controllable, well-ordered TiO₂ nanotube array layer could be fabricated in a short time. The diameters of the as-prepared TiO₂ nanotubes could be adjusted from 20 to 150 nm, and the thickness could be adjusted from a few hundred nanometers to several micrometers. The photoresponse and the photocatalytic activity of the highly ordered TiO₂ nanotube array films were also examined. The nanotube array film with a thickness of about 2.5 μm had the highest incident photon to photocurrent conversion efficiency (IPCE) (34.3%) at the 350 nm wavelength, and had better charge transfer ability under UV light illumination. The photocatalytic experimental results indicated that the 450 °C annealing samples have the highest photodegradation efficiency for methyl orange pollutant.     

Effect of nano‐TiO2 dispersion on PEO polymer electrolyte property

Polymer electrolyte membranes based on poly(ethylene oxide) (PEO) doped with TiO₂ nanoparticles were synthesized by simple solution cast technique. Mesoporous TiO₂ film was prepared by doctor‐blade method. The modified polymer membranes and the mesoporous films were characterized by SEM, TEM, AFM, ionic conductivity, and J‐V measurements. Dye‐sensitized solar cells (DSSC) have been fabricated in which PEO‐polymer electrolyte doped with and without nano‐TiO₂ were sandwiched between porous TiO₂ and counter electrodes. The DSSC with nano‐TiO₂ doped polymer electrolyte shows better performance (1.68%) in comparison with pristine polymer electrolyte (1.07%), which is due to improved ionic conductivity value in polymer electrolyte system by nano‐TiO₂ doping. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Efficiency enhancement in dye sensitized solar cells based on PAN gel electrolyte with Pr4NI + MgI2 binary iodide salt mixture

The effect of using a binary iodide salt mixture in N719 dye-sensitized TiO₂ solar cells (DSSCs) is investigated. The cells use tetrapropylammonium iodide (Pr₄NI) and magnesium iodide (MgI₂) in a plasticized polyacrylonitrile gel in glass/FTO/nano-porous TiO₂/gel, I₂/Pt/FTO/glass solar cell structure. The salt composition in the gel electrolyte is varied to optimize the efficiency of DSSCs. The DSSCs with MgI₂ or Pr₄NI as the only iodide salt showed the efficiencies 2.56 and 4.16 %, respectively, under AM 1.5 (100 mW cm^?2) illumination while the DSSC with mixed cations with 18.4:81.6 MgI₂:Pr₄NI molar ratio shows the highest efficiency of 5.18 %. Thus the efficiency enhancement, relative to the high efficiency end member is about 25 %. DC polarization measurements establish the predominantly ionic behavior of the electrolytes, and show that the variation of efficiency with salt composition correlates with the change in short circuit photocurrent density (J _sc), which appears to be governed by the iodide ion conductivity. It is also found that J _sc correlates with the iodide ion transference number estimated from DC polarization data taken with non-blocking iodine electrodes. This study suggests that binary iodide mixtures may be used to obtain efficiency enhancement in different types of DSSCs based on polymeric, gel, or solvent electrolytes.     

Electrophoretic Deposition of Zirconia Thin Film on Nonconducting Substrate for Solid Oxide Fuel Cell Application

Electrophoretic deposition (EPD) of 8 mol% yttria‐stabilized zirconia (YSZ) electrolyte thin film has been carried out onto nonconducting porous NiO‐YSZ cermet anode substrate using a fugitive and electrically conducting polymer interlayer for solid oxide fuel cell (SOFC) application. Such polymer interlayer burnt out during the high‐temperature sintering process (1400°C for 6 h) leaving behind a well adhered, dense, and uniform ceramic YSZ electrolyte film on the top of the porous anode substrate. The EPD kinetics have been studied in depth. It is found that homogeneous and uniform film could be obtained onto the polymer‐coated substrate at an applied voltage of 15 V for 1 min. After the half‐cell (anode + electrolyte) is co‐fired at 1400°C, a suitable cathode composition (La_0.65Sr_0.3MnO₃) thick film paste is screen printed on the top of the sintered YSZ electrolyte. A second stage of sintering of such cathode thick film at 1100°C for 2 h finally yield a single cell SOFC. Such single cell produced a power output of 0.91 W/cm² at 0.7 V when measured at 800°C using hydrogen and oxygen as fuel and oxidant, respectively.     

Characterization of poly(vinylidenefluoride-co-hexafluoropropylene)-based polymer electrolyte filled with TiO2 nanoparticles

Nanoscale TiO₂ particle filled poly(vinylidenefluoride-co-hexafluoropropylene) film is characterized by investigating some properties such as surface morphology, thermal and crystalline properties, swelling behavior after absorbing electrolyte solution, chemical and electrochemical stabilities, ionic conductivity, and compatibility with lithium electrode. Decent self-supporting polymer electrolyte film can be obtained at the range of <50 wt% TiO₂. Different optimal TiO₂ contents showing maximum liquid uptake may exist by adopting other electrolyte solution. Room temperature ionic conductivity of the polymer electrolyte placed surely on the region of >10⁻³ S/cm, and thus the film is very applicable to rechargeable lithium batteries. An emphasis is also be paid on that much lower interfacial resistance between the polymer electrolyte and lithium metal electrode can be obtained by the solid-solvent role of nanoscale TiO₂ filler.     

Plasmonic Effects of Infiltrated Silver Nanoparticles Inside TiO2 Film: Enhanced Photovoltaic Performance in DSSCs

The plasmonic effects of infiltrated silver (Ag) nanoparticles, with different contents, inside a nanostructured TiO₂ film on the photovoltaic performance of dye‐sensitized solar cells (DSSCs) are explored. The synthesized Ag nanoparticles are immobilized onto deposited TiO₂ nanoparticles by a new strategy using 3‐mercaptopropionic acid (MPA), a bifunctional linker molecule. Transmission electron microscope (TEM) images show that monodispersed Ag and polydispersed TiO₂ nanoparticles have an average diameter of 12 ± 3 nm and 5 ± 1 nm, respectively. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis reveals that Ag nanoparticles were successfully functionalized and capped with MPA. Optical studies on the MPA‐capped Ag nanoparticles inside TiO₂ film show an increase in the total absorbance of the electrode. Moreover, EIS measurements confirm that MPA‐capped Ag nanoparticles inhibit the charge recombination and improve the stability of nanoparticles in I₃^?/I^? electrolyte. The DSSC assembled with optimal content of MPA‐capped Ag nanoparticles demonstrated an enhanced power conversion efficiency (8.82% ± 0.07%) compared with the pure TiO₂ (7.30% ± 0.05%). The increase in cell efficiency was attributed to the enhanced dye light absorption in strength and spectral range due to the surface plasmon resonance of MPA‐capped Ag nanoparticles in the photoanode.     

EIS analysis on low temperature fabrication of TiO2 porous films for dye-sensitized solar cells

A low temperature (<150 °C) fabrication method for preparation of TiO₂ porous films with high efficiency in dye-sensitized solar cells (DSSCs) has been developed. The Ti(IV) tetraisopropoxide (TTIP) was added to the paste of TiO₂ nanoparticles to interconnect the TiO₂ particles. The electrochemical impedance spectroscopy (EIS) technique was employed to quantify the charge transport resistance at the TiO₂/dye/electrolyte interface (R_ct2) and electron lifetime in the TiO₂ film (τ_e) under different molar ratios of TTIP/TiO₂ and also at various TiO₂ thicknesses. It was found that the R_ct2 decreased as the molar ratio increased from 0.02 to 0.08, however, it increased at a molar ratio of 0.2 due to the reduction in surface area for dye adsorption. In addition, the characteristic frequency peak shifted to lower frequency at a molar ratio of 0.08, indicating the longer electron lifetime. As for the thickness effect, TiO₂ film with a thickness around 17 μm achieved the best cell efficiency. EIS study also confirmed that, under illumination, the smallest R_ct2 was associated with a TiO₂ thickness of 17 μm, with the R_ct2 increased as the thickness of TiO₂ film increased. In the Bode plots, the characteristic frequency peaks shifted to higher frequency when the thickness of TiO₂ increased from 17.2 to 48.2 μm, indicating the electron recombination increases as the thickness of the TiO₂ electrode increases.Finally, to make better use of longer wavelength light, 30 wt% of larger TiO₂ particle (300 nm) was mixed with P25 TiO₂ as light scattering particles. It effectively increased the short-circuit current density and cell conversion efficiency from 7.44 to 8.80 mA cm⁻² and 3.75 to 4.20%, respectively.     

Influence of 2,6 (N-pyrazolyl)isonicotinic acid on the photovoltaic properties of a dye-sensitized solar cell fabricated using poly(vinylidene fluoride) blended with poly(ethylene oxide) polymer electrolyte

A novel method of introducing a synthesized organic nitrogenous compound 2,6 (N-pyrazolyl)isonicotinic acid (BNIN) and its effect on the conduction behavior of poly(vinylidene fluoride) (PVdF)–poly(ethylene oxide) (PEO) polymer-blend electrolyte with potassium iodide (KI) and iodine (I₂) and the corresponding performance of the dye-sensitized solar cells (DSSCs) were studied. A systematic investigation of the blends using FTIR provides evidence of interaction of BNIN with the polymer. Differential scanning calorimetry (DSC) study proves the miscibility of these polymers. Due to the coordinating and plasticizing effects of BNIN, the ionic conductivity of polymer blend electrolytes is enhanced. The efficiency of DSSC using BNIN doped polymer blend electrolyte was 7.3% under an illumination of 60 mW cm⁻² were observed for the best performance of a solar cell in this work.     

Enhancement of photoelectric conversion by high-voltage electric field assisted crystallization of a novel ternary-encapsulated spherical TiO2 aggregate for solar cells

A novel ternary-encapsulated spherical TiO₂ aggregate (TES-TiO₂) with submicron particle sizes was formed by blending commercial P25 TiO₂ and two different sizes of TiO₂ particles (synthesized by modified sol-gel and hydrothermal methods). A double-layered TiO₂ electrode for dye-sensitized solar cells (DSSCs) was fabricated by depositing TES-TiO₂ particles onto nanocrystalline mesoporous TiO₂ (Meso-TiO₂)-coated FTO glass by a cathodic electrophoresis technique and then calcined at 450 °C for 30 min. Compared to double-layered Meso-TiO₂/P25 electrodes, the energy conversion efficiency (η) of DSSCs from the obtained Meso-TiO₂/TES-TiO₂ electrode was improved by 9.3%, from 5.94% to 6.49%. When the prepared double-layered Meso-TiO₂/TES-TiO₂ electrode was calcined at high temperature, a high-voltage electric field (HVEF) was introduced to assist crystallization. As a result, η was further enhanced by 8.6%, from 6.49% to 7.05%. Notably, compared to typical 20 nm TiO₂ nanocrystallites applied in the active layer of DSSCs, the prepared loosely porous TES-TiO₂ with submicron size increased the light-scattering effect and promoted dye molecule adsorption and the diffusion of electrolytes. In addition, introduction of the HVEF provided better connection among TiO₂ particles, which facilitated electron transport and avoided charge recombination.     

Crystallinity, morphology, mechanical properties and conductivity study of in situ formed PVdF/LiClO4/TiO2 nanocomposite polymer electrolytes

Nanocomposite polymer electrolytes composed of poly(vinylidene fluoride) (PVdF), lithium perchlorate (LiClO₄) and TiO₂ nanoparticles were prepared by a solution-cast method. The nanosized ceramic filler, TiO₂, was synthesized in situ by a sol-gel process. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analysis revealed that the crystalline phase and crystallinity were slightly decreased with the addition of TiO₂ to the PVdF/LiClO₄ system. Scanning electron microscopy (SEM) micrographs showed that the PVdF/LiClO₄/TiO₂ solid polymer electrolyte (SPE) membranes had a porous structure to a certain extent, and that the pore size decreased with increasing TiO₂ content. The overfull nanoparticles tended to aggregate on the surface and inside the pores at TiO₂ content above 15 wt.% so that the porosity decreased. Regarding mechanical properties, the strength of the PVdF/LiClO₄/TiO₂ electrolytes decreased after the uptake of EC/PC solution. In contrast to the conductive behavior of wet PVdF/LiClO₄/TiO₂ membranes relative to the uptake of EC/PC solution, the conductive mechanism of the solid membranes, after the lithium ion of LiClO₄ had already been installed in the PVdF solid polymer network, was mainly influenced by the TiO₂ nanoparticles. At a TiO₂ content of 10 wt.%, the solid and wet PVdF/LiClO₄/TiO₂ systems had the maximum conductivity values of 7.1 × 10⁻⁴ and 1.8 × 10⁻³ S/cm, respectively.