The network gel polymer electrolyte based on poly(acrylate-co-imide) and its transport properties in lithium ion batteries

Poly (acrylate-co-imide)-based gel polymer electrolytes are synthesized by in situ free radical polymerization. Infrared spectroscopy confirms the complete polymerization of gel polymer electrolytes. The ionic conductivity of gel polymer electrolytes are measured as a function of different repeating EO units of polyacrylates. An optimal ionic conductivity of the poly (PEGMEMA₁₁₀₀-BMI) gel polymer electrolyte is determined to be 4.8 × 10^–3 S/cm at 25 °C. The lithium transference number is found to be 0.29. The cyclic voltammogram shows that the wide electrochemical stability window of the gel polymer electrolyte varies from −0.5 to 4.20 V (vs. Li/Li⁺). Furthermore, we found the transport properties of novel gel polymer electrolytes are dependent on the EO design and are also related to the rate capability and the cycling ability of lithium polymer batteries. The relationship between polymer electrolyte design, lithium transport properties and battery performance are investigated in this research.     

Enhanced electrochemical properties of polyethylene oxide-based composite solid polymer electrolytes with porous inorganic–organic hybrid polyphosphazene nanotubes as fillers

Solid composite polymer electrolytes consisting of polyethylene oxide (PEO), LiClO₄, and porous inorganic–organic hybrid poly (cyclotriphosphazene-co-4, 4′-sulfonyldiphenol) (PZS) nanotubes were prepared using the solvent casting method. Differential scanning calorimetry and scanning electron microscopy were used to determine the characteristics of the composite polymer electrolytes. The ionic conductivity, lithium ion transference number, and electrochemical stability window can be enhanced after the addition of PZS nanotubes. The electrochemical impedance showed that the conductivity was improved significantly. Maximum ionic conductivity values of 1.5 × 10⁻⁵ S cm⁻¹ at ambient temperature and 7.8 × 10⁻⁴ S cm⁻¹ at 80 °C were obtained with 10 wt.% content of PZS nanotubes, and the lithium ion transference number was 0.35. The good electrochemical properties of the solid-state composite polymer electrolytes suggested that the porous inorganic–organic hybrid polyphosphazene nanotubes had a promising use as fillers in SPEs and the PEO₁₀–LiClO₄–PZS nanotube solid composite polymer electrolyte might be used as a candidate material for lithium polymer batteries.     

Magnesium ion-conducting gel polymer electrolytes dispersed with fumed silica for rechargeable magnesium battery application

Effect of fumed silica dispersion on poly(vinylidene fluoride-co-hexafluoropropylene)-based magnesium ion-conducting gel polymer electrolyte has been studied using various physical and electrochemical techniques. The composite gel electrolytes are free-standing and flexible films with enough mechanical strength. The optimized composition with 3 wt.% filler offers a maximum ionic conductivity of ∼1.1 × 10⁻² S cm⁻¹ at ∼25 °C with good thermal and electrochemical stabilities. The Mg²⁺ ion conduction in the gel nanocomposite film is confirmed from the cyclic voltammetry, impedance spectroscopy, and transport number measurements. The space-charge layers formed between filler particles and gel electrolyte are responsible for the enhancement in ionic conductivity. The applicability of the gel nanocomposite to a rechargeable battery is examined by fabricating a prototype cell consisting of Mg [or Mg-multiwalled carbon nanotube (MWCNT) composite] and MoO₃ as negative and positive electrodes, respectively. The discharge capacity and the rechargeability of the cell have been improved when Mg metal is substituted by Mg-MWCNT composite. The discharge capacity of the optimized cell has found to be ∼175 mAh g⁻¹ of MoO₃ for an initial ten charge–discharge cycles.     

The effects of polymer gel electrolyte composition on performance of quasi-solid-state dye-sensitized solar cells

Polymer gel electrolytes based on poly(acrylic acid)-poly(ethylene glycol) (PAA–PEG) hybrid have been prepared and applied to developed quasi-solid-state dye-sensitized solar cells (DSCs). PAA–PEG hybrid was synthesized by polymerization reaction. Quasi-solid-state DSCs were fabricated with synthesized PAA–PEG electrolyte. The effects of alkali iodides LiI, KI, and I₂ concentrations on liquid electrolyte absorbency and ionic conductivity of PAA–PEG were investigated. The evolution of the solar cell parameters with polymer gel electrolyte compositions was revealed. DSCs based on PAA–PEG with optimized KI/I₂ concentrations showed better performances than those with optimized LiI/I₂ concentrations. The electrochemical impedance spectroscopy technique was employed to examine the electron lifetime in the TiO₂ electrode and quantify charge transfer resistances at the TiO₂/dye/electrolyte interface and the counter electrode in the solar cells based on the PAA–PEG hybrid gels. A maximum conversion efficiency of 4.96% was obtained for DSCs using KI based quasi-solid electrolyte under 100 mW cm⁻². Our work suggests that KI can be the promising alkali metal iodide for improving the performance of PAA–PEG hybrid gel DSCs.     

Enhanced zinc ion transport in gel polymer electrolyte: effect of nano-sized ZnO dispersion

The effect of the dispersion of zinc oxide (ZnO) nanoparticles in the zinc ion conducting gel polymer electrolyte is studied. Changes in the morphology/structure of the gel polymer electrolyte with the introduction of ZnO particles are distinctly observed using X-ray diffraction and scanning electron microscopy. The nanocomposites offer ionic conductivity values of >10^?3 S cm^?1 with good thermal and electrochemical stabilities. The variation of ionic conductivity with temperature follows the Vogel–Tamman–Fulcher behavior. AC impedance spectroscopy, cyclic voltammetry, and transport number measurements have confirmed Zn²⁺ ion conduction in the gel nanocomposites. An electrochemical stability window from ?2.25 to 2.25 V was obtained from voltammetric studies of nanocomposite films. The cationic (i.e., Zn²⁺ ion) transport number (t ₊) has been found to be significantly enhanced up to a maximum of 0.55 for the dispersion of 10 wt.% ZnO nanoparticles, indicating substantial enhancement in Zn²⁺ ion conductivity. The gel polymer electrolyte nanocomposite films with enhanced Zn²⁺ ion conductivity are useful as separators and electrolytes in Zn rechargeable batteries and other electrochemical applications.     

Synthesis and electrochemical characterization of aPEO-based polymer electrolytes

In this paper, the preparation and purification of an amorphous polymer network, poly[oxymethylene-oligo(oxyethylene)], designated as aPEO, are described. The flexible CH₂CH₂O segments in this host polymer combine appropriate mechanical properties, over a critical temperature range from −20 to 60 °C, with labile salt-host interactions. The intensity of these interactions is sufficient to permit solubilisation of the guest salt in the host polymer while permitting adequate mobility of ionic guest species. We also report the preparation and characterisation of a novel polymer electrolyte based on this host polymer with lithium tetrafluoroborate, LiBF₄, as guest salt. Electrolyte samples are thermally stable up to approximately 250 °C and completely amorphous above room temperature. The electrolyte composition determines the glass transition temperature of electrolytes and was found to vary between −50.8 and −62.4 °C. The electrolyte composition that supports the maximum room temperature conductivity of this electrolyte system is n = 5 (2.10 × 10⁻⁵ S cm⁻¹ at 25 °C). The electrochemical stability domain of the sample with n = 5 spans about 5 V measured against a Li/Li⁺ reference. This new electrolyte system represents a promising alternative to LiCF₃SO₃ and LiClO₄-doped PEO analogues.     

Electrical and electrochemical studies on magnesium ion-based polymer gel electrolytes

The development of polymer gel electrolyte system with high ionic conductivity is the main objective of polymer research. Electrochemical devices based on lithium ion-conducting polymer electrolyte are not safe due to the explosive nature of lithium. An attempt has been made to synthesize magnesium ion-conducting polymeric gel electrolytes, poly (vinylidene fluoride-co-hexafluoropropylene)–propylene carbonate–magnesium perchlorate, PVdF(HFP)-PC–Mg(ClO₄)₂ using standard solution-cast techniques. The maximum room temperature ionic conductivity of the synthesized electrolyte system has been observed to be 5.0 × 10⁻³ S cm⁻¹, which is quite acceptable from a device fabrication point of view. The temperature-dependent conductivity and the dielectric behavior were also analyzed. The pattern of the temperature-dependent conductivity shows the Arrhenius behavior. The dielectric constant ε _r and dielectric loss ε _i increases with temperature in the low-frequency region but almost negligible in the high-frequency region. This behavior can be explained on the basis of electrode polarization effects. The real part M _r and imaginary part M _i versus frequency indicate that the systems are predominantly ionic conductors. Further, the synthesized electrolyte materials have been checked for its suitability in energy storage devices namely redox supercapacitor with conducting polymer polypyrrole as electrode materials, and finally, it was observed that it shows good capacitive behavior in low-frequency region. Preliminary studies show that the overall capacitance of 22 mF cm⁻² which is equivalent to a single electrode specific capacitance of 117 F gm⁻¹ was observed for the above said supercapacitors.     

Improved properties of polymer electrolyte by ionic liquid PP1.3TFSI for secondary lithium ion battery

A new kind of polymer electrolyte is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP1.3TFSI), polyethylene oxide (PEO), and lithium bis (trifluoromethanesulfonyl) imide (LiTFSI). IR and X-ray diffraction results demonstrate that the addition of ionic liquid decreases the crystallization of PEO. Thermal and electrochemical properties have been tested for the solid polymer electrolytes, the addition of the room temperature molten salt PP1.3TFSI to the conventional P(EO)₂₀LiTFSI polymer electrolyte leads to the improvement of the thermal stability and the ionic conductivity (x = 1.27, 2.06 × 10⁻⁴ S cm⁻¹ at room temperature), and the reasonable lithium transference number is also obtained. The Li/LiFePO₄ cell using this polymer electrolyte shows promising reversible capacity, 120 mAh g⁻¹ at room temperature and 164 mAh g⁻¹ at 55 °C.     

Effect of nanoscale CeO<Subscript>2</Subscript> on PVDF-HFP-based nanocomposite porous polymer electrolytes for Li-ion batteries

New poly (vinylidenefluoride-co-hexafluoro propylene) (PVDF-HFP)/CeO₂-based microcomposite porous polymer membranes (MCPPM) and nanocomposite porous polymer membranes (NCPPM) were prepared by phase inversion technique using N-methyl 2-pyrrolidone (NMP) as a solvent and deionized water as a nonsolvent. Phase inversion occurred on the MCPPM/NCPPM when it is treated by deionized water (nonsolvent). Microcomposite porous polymer electrolytes (MCPPE) and nanocomposite porous polymer electrolytes (NCPPE) were obtained from their composite porous polymer membranes when immersed in 1.0 M LiClO₄ in a mixture of ethylene carbonate/dimethyl carbonate (EC/DMC) (v/v = 1:1) electrolyte solution. The structure and porous morphology of both composite porous polymer membranes was examined by scanning electron microscope (SEM) analysis. Thermal behavior of both MCPPM/NCPPM was investigated from DSC analysis. Optimized filler (8 wt% CeO₂) added to the NCPPM increases the porosity (72%) than MCPPM (59%). The results showed that the NCPPE has high electrolyte solution uptake (150%) and maximum ionic conductivity value of 2.47 × 10⁻³ S cm⁻¹ at room temperature. The NCPPE (8 wt% CeO₂) between the lithium metal electrodes were found to have low interfacial resistance (760 Ω cm²) and wide electrochemical stability up to 4.7 V (vs Li/Li⁺) investigated by impedance spectra and linear sweep voltammetry (LSV), respectively. A prototype battery, which consists of NCPPE between the graphite anode and LiCoO₂ cathode, proves good cycling performance at a discharge rate of C/2 for Li-ion polymer batteries.     

Laser Raman and conductivity studies of plasticized polymer electrolyte P(ECH-EO):propylenecarbonate:<Emphasis Type="Italic">γ</Emphasis>-butyrolactone:LiClO<Subscript>4</Subscript>

The plasticized polymer electrolytes composed of poly(epichlorohydrin-ethyleneoxide) (P(ECH-EO)) as host polymer, lithium perchlorate (LiClO₄) as salt, γ-butyrolactone (γ-BL), and propylene carbonate (PC) as plasticizer have been prepared by simple solution casting technique. The effect of mixture of plasticizers γ-BL and PC on conductivity of the polymer electrolyte P(ECH-EO):LiClO₄ has been studied. The band at 457 cm⁻¹ in the Raman spectra of plasticized polymer electrolyte is attributed to both the ring twisting mode of PC and the perchlorate ν ₂(ClO₄⁻) bending. The maximum conductivity value is observed to be 4.5 × 10⁻⁴ S cm⁻¹ at 303 K for 60P(ECH-EO):15PC:10γ-BL:15LiClO₄ electrolyte system. In the present investigation, an attempt has been made to correlate the Raman and conductivity data.     

A polymer electrolyte containing ionic liquid for possible applications in photoelectrochemical solar cells

Various iodide ion conducting polymer electrolytes have been studied as candidate materials for fabricating photoelectrochemical (PEC) solar cells and energy storage devices. In this study, enhanced ionic conductivity values were obtained for the ionic liquid tetrahexylammonium iodide containing polyethylene oxide (PEO)-based plasticized electrolytes. The analysis of thermal properties revealed the existence of two phases in the electrolyte, and the conductivity measurements showed a marked conductivity enhancement during the melting of the plasticizer-rich phase of the electrolyte. Annealed electrolyte samples showed better conductivity than nonannealed samples, revealing the existence of hysteresis. The optimum conductivity was shown for the electrolytes with PEO:salt = 100:15 mass ratio, and this sample exhibited the minimum glass transition temperature of 72.2 °C. For this optimum PEO to salt ratio, the conductivity of nonannealed electrolyte was 4.4 × 10⁻⁴ S cm⁻¹ and that of the annealed sample was 4.6 × 10⁻⁴ S cm⁻¹ at 30 °C. An all solid PEC solar cell was fabricated using this annealed electrolyte. The short circuit current density (I _SC), the open circuit voltage (V _OC), and the power conversion efficiency of the cell are 0.63 mA cm⁻², 0.76 V, and 0.47% under the irradiation of 600 W m⁻² light.     

Structure and ion transport in an ethylene carbonate-modified biodegradable gel polymer electrolyte

The influence of ethylene carbonate (EC) addition on 85poly(ε-caprolactone):15Lithium thiocyanate (85PCL:15LiSCN) polymer electrolyte is investigated using X-ray diffraction, impedance spectroscopy, Wagner's polarization and electrochemical measurements. The results reveal that the amorphicity of the 85PCL:15LiSCN system increases with increase of EC content up to an optimal level of 40 wt.%. This is reflected in the electrical properties of the gel polymer electrolytes, i.e., the 40 wt.% EC-incorporated gel polymer electrolyte exhibits both high amorphicity and high electrical conductivity as compared to the other samples. The EC concentration dependences of dielectric constant and electrical conductivity show a similar trend, indicating that these properties are closely related to each other. The total ionic transference numbers of EC-incorporated gel polymer electrolytes are in the range 0.989–0.993, demonstrating that they are almost completely ionic conductors. The electrochemical stability window of the 40 wt.% EC-incorporated gel polymer electrolyte is ∼4.1 V along with the electrical conductivity of 2.2 × 10⁻⁴ S cm⁻¹, which is significantly improved as compared to the 85PCL:15LiSCN system (3.0 V and 1.04 × 10⁻⁶ S cm⁻¹). Consequently, the addition of EC in the 85PCL:15LiSCN polymer electrolyte leads to a promising improvement in its various properties.     

Electrochemical modification of Bi2S3 coatings in a nickel plating electrolyte

The electrochemical behavior of Bi₂S₃ coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi₂S₃ and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S²⁻ ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni²⁺ ions reduction before the bulk deposition of Ni, initiated by Bi₂S₃. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 10¹³ to 500–700 Ω cm. A metal-rich mixed sulfide Ni₃Bi₂S₂–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential close to the equilibrium potential of the Ni/Ni²⁺ system and then annealed at temperatures higher than 120 °C.     

In situ formation of polyethylene glycol–titanium complexes as solvent-free electrolytes for electrochromic device application

Transparent and ionic conductive polymeric electrolytes have been prepared through sol–gel method by adding titanium isopropoxide into an acidic polyethylene glycol (PEG) solution. After hydrolysis and condensation processes, new associations between titanium cations and ether oxygen atoms of PEG have been formed according to Fourier-transform infrared spectroscopy. Thermogravimetric analysis results of these hybrid materials indicate a better thermal stability with a less polydispersion of the molecular mass distribution in comparison with PEG. For the purpose of electrochromic or photoelectrochromic device applications, LiI was added into the hybrid materials to form solvent-free polymeric electrolytes. Optical transmittance spectra of these electrolytes show a red shift of the cutoff wavelength as a function of titanium isopropoxide percentage in the original sol–gel solutions. It is also observed that the amount of hydroxyl groups in the hybrid materials was reduced in comparison with the PEG one. This makes electrical conductivity of the hybrid electrolytes with LiI salt insensitive to humidity and solvents, which was about 2 × 10^-4 Ω⁻¹ cm⁻¹ at room temperature. A solid WO₃-based electrochromic device with the hybrid electrolyte keeps the same optical transmittance value after 1,000 cycles of switching polarization potentials between −1 and +1 V.     

Polyethylene-supported poly(acrylonitrile-co-methyl methacrylate)/nano-Al2O3 microporous composite polymer electrolyte for lithium ion battery

Nano-Al₂O₃ was doped in poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), and polyethylene(PE)-supported P(AN-co-MMA)/nano-Al₂O₃ microporous composite polymer electrolyte (MCPE) was prepared. The performances of the prepared MCPE for lithium ion battery use, including ionic conductivity, electrochemical stability, interfacial compatibility, and cyclic stability, were studied by scanning electron spectroscopy, linear sweep voltammetry, and electrochemical impedance spectroscopy. It is found that the nano-Al₂O₃ significantly affects the MCPE performances. Compared to the MCPE without any nano-Al₂O₃, the MCPE with 10 wt.% nano-Al₂O₃ reaches its best performances. Its ionic conductivity is improved from 2.0 × 10⁻³ to 3.2 × 10⁻³ S cm⁻¹, its decomposition potential is enhanced from 5.5 to 5.7 V (vs Li/Li⁺), and its interfacial resistance on lithium is reduced from 520 to 160 Ω cm². Thus, the battery performance is improved.     

Performance of gelled-type dye-sensitized solar cells associated with glass transition temperature of the gelatinizing polymers

Poly(methyl acrylate) (PMA), poly(vinyl acetate) (PVAc) and poly(n-isopropylacrylamide) (PNIPAAm) with their respective T_g of 6, 32, and 145 °C were employed to gel the LiI/I₂/tertiary butylpyridine electrolyte system for preparation of the gelled-type dye-sensitized solar cells (DSSC). The light-to-electricity conversion efficiencies of DSSCs gelled by PMA, PVAc, and PNIPAAm were 7.17%, 5.62%, and 3.17%, respectively under simulated AM 1.5 sunlight irradiation, implying that utilizing the polymer of lower T_g to gel the electrolytes leaded to better performance of the DSSCs. Their short-circuit current density and IPCE also showed the similar trend. Electrochemical impedance spectroscopy of the gelled DSSCs revealed that utilizing the polymer of lower T_g resulted in lower impedance associated with the Nernstian diffusion within the electrolytes. The results were consistent with the observation that the molar conductivity of gelled electrolytes was higher as the polymer of lower T_g was applied, which can be justified by Vogel-Tammann-Fulcher (VTF) equation.     

High ionic conductive PVDF-based fibrous electrolytes

The high ionic conductive polymer electrolytes were prepared based on poly(vinylidenefluoride) (PVDF) fibers modified via preirradiation grafting poly(methyl methacrylate) (PMMA). In these polymer electrolytes, the PVDF fibers served as the supporting phase providing dimensional stability, and PMMA acted as the gel phase helping for the trapping liquid electrolyte and substituting the nonconductive PVDF phase to provide contact with electrodes well thus increasing conductive area. The modified PVDF fibrous membranes were used as a polymer electrolyte in lithium ion battery after they were activated by uptaking 1 M LiPF₆/ethylene carbonate–dimethyl carbonate (1:1 vol) liquid electrolyte, which showed a much higher room-temperature ionic conductivity than the pristine PVDF fibrous membrane. The LiCoO₂-mesocarbon microbead coin cells containing the dual-phase fibrous membrane (degree of graft, 111.8%) demonstrated excellent rate performance, and the cell still retained about 86% of discharge capacity at 4C rate, as compared to that at 0.1C rate. The prototype cell showed good cycle performance.     

Development of sulfide glass-ceramic electrolytes for all-solid-state lithium rechargeable batteries

Development of Li₂S–P₂S₅-based glass-ceramic electrolytes is reviewed. Superionic crystals of Li₇P₃S₁₁ and Li_3.25P_0.95S₄ were precipitated from the Li₂S–P₂S₅ glasses at the selected compositions. These high temperature or metastable phases enhanced conductivity of glass ceramics up to over 10⁻³ S cm⁻¹ at room temperature. The original (or mother) glass electrolytes itself showed somewhat lower conductivity of 10⁻⁴ S cm⁻¹ and have important role as a precursor for obtaining the superionic crystals, which were not synthesized by a conventional solid-state reaction. The substitution of P₂O₅ for P₂S₅ at the composition 70Li₂S·30P₂S₅ (mol%) improved both conductivity and electrochemical stability of glass-ceramic electrolytes. The all-solid-state In/LiCoO₂ cell using the 70Li₂S·27P₂S₅·3P₂O₅ (mol%) glass-ceramic electrolyte showed initial capacity of 105 mAh g⁻¹ (gram of LiCoO₂) at the current density of 0.13 mA cm⁻² and exhibited higher electrochemical performance than that using the 70Li₂S·30P₂S₅ glass-ceramic electrolyte.     

Lithium-ion conduction in elastomeric binder in Li-ion batteries

This paper describes two kinds of elastomeric binders which are styrene–butadiene (ST–BD) copolymer and 2-ethylhexyl acrylate–acrylonitrile (2EHA–AN) copolymer for electrode materials of rechargeable Li-ion batteries. These elastomeric binders were swollen by electrolyte solution (EC/DEC=1/2, 1 M LiPF₆), and 2EHA–AN copolymer retained larger amount of electrolyte solution than ST–BD copolymer. The Li-ionic conduction behavior was investigated for both copolymer films swollen by electrolyte solution. The Li-ion conductivity of ST–BD copolymer was 9.45 × 10⁻⁸ S·cm⁻¹ and that of 2EHA–AN copolymer was 1.25 × 10⁻⁵ S·cm⁻¹ at room temperature, and the corresponding amounts of activation energy were 0.31 and 0.26 eV, respectively. Because the observed activation energy in elastomeric binder was different from that in the bulk of electrolyte solution (0.09 eV), Li-ion conduction of the bulk of elastomeric binder swollen by electrolyte was affected by the polymer structure of binders. Electrochemical performance of cathode material, LiCoO₂, was investigated with three kinds of binders: ST–BD copolymer, 2EHA–AN copolymer, and poly(vinylidene fluoride). The initial charge–discharge capacity of the LiCoO₂ electrode with 2EHA–AN copolymer showed highest capacity, suggesting that Li⁺-ion conduction inside of the elastomeric binder contributes to the enhancement of charging and discharging capacity. This result indicates that elastomeric binder with sufficient Li-ionic conductivity can be an attractive candidate for improving cathode of lithium-ion battery.     

Investigations on poly(methyl methacrylate)-poly(ethylene oxide) hybrid polymer electrolytes with dioctyl phthalate, dimethyl phthalate and diethyl phthalate as plasticizers

Plasticizers can be used to change the mechanical and electrical properties of polymer electrolytes by reducing the degree of crystallinity and lowering the glass transition temperature. The transport properties of gel-type ionic conducting membranes consisting of poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), LiClO₄ and dioctyl phthalate, diethyl phthalate or dimethyl phthalate (DMP) are studied. The polymer films are characterized by X-ray diffraction, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as the plasticizer in the PEO-PMMA-LiClO₄ polymer complex favours an enhancement in ionic conductivity. The maximum conductivity value obtained for the solid polymer electrolyte film at 305 K is 3.529×10^{– 4} S cm^–1. Electronic Publication