Thin-film Polymer Electrolyte Research Articles

Electrolysis on a Chip with Tunable Thin Film Nanostructured PGM Electrocatalysts Generated from Self-Assembled Block Copolymer Templates.

Self-assembled block copolymers are promising templates for fabricating thin film materials with tuned periodic feature sizes and geometry at the nanoscale. Here, a series of nanostructured platinum and iridium oxide electrocatalysts templated from poly(styrene)-block-poly(vinyl pyridine) (PSbPVP) block copolymers via an incipient wetness impregnation (IWI) pathway is reported. Both nanowire and nanocylinder electrocatalysts of varying feature sizes are assessed and higher catalyst loadings are achieved by the alkylation of the pyridine moieties in the PVP block prior to IWI. Electrocatalyst evaluations featuring hydrogen pump and water electrolysis demonstrations are carried out on interdigitated electrode (IDE) chips flexible with liquid supporting electrolytes and thin film polymer electrolytes. Notably, the mass activities of the nanostructured electrocatalysts from alkylated block copolymer templates are 35%-94% higher than electrocatalysts from non-alkylated block copolymer templates. Standing cylinder nanostructures lead to higher mass activities than lamellar variants despite their not having the largest surface area per unit catalyst loading demonstrating that mesostructure architectures have a profound impact on reactivity. Overall, IDE chips with model thin film electrocatalysts prepared from self-assembled block copolymers offer a high-throughput experimental method for correlating electrocatalyst nanostructure and composition to electrochemical reactivity.

Effect of carbon nanotubes as dispersoid in polymer electrolyte matrix

The present work deals with the characterization of a thin film polymer electrolyte based on poly(N-vinyl pyrrolidone) (PVP) doped with ammonium iodide (NH4I) and carbon nanotubes (CNT) as dispersoid to develop nanocomposite polymer electrolyte films using solution cast method. Carbon nanotubes were incorporated in PVP:NH4I matrix in different concentration. Electrochemical impedance spectroscopy technique was used for characterizing the polymer electrolyte system. 0.4 wt% MCNT containing system shows maximum conductivity (8.23 × 10−2 S/cm). The temperature dependent conductivity studies reveal the Arrhenius behavior. Differential scanning calorimetry analysis shows the decrease in the glass transition temperature (Tg) from 345 (60:40 PVP:NH4I) to 339 K (60:40 + 0.4 wt% PVP:NH4I + CNT). Dielectric phenomenon, concentration of charge carrier density (N) and dissociation factor also supports the conductivity data while ionic transference number (tion) studies confirms the ionic conductive nature of the electrolyte system.

Employment of [Amim] Cl in the effort to upgrade the properties of cellulose acetate based polymer electrolytes

Transparent thin film polymer electrolytes were prepared by solvent casting technique with the doping of environmental-friendly ionic liquid, 1-allyl-3-methylimidazolium chloride ([Amim] Cl) into the matrix formed by cellulose acetate (CA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The ionic conducting nature of this system improves significantly from the order of 10−7–10−2 S cm−1 upon increasing doping of [Amim] Cl content till a maximum of 4.68 × 10−2 S cm−1 is attained for the composition CA:LiTFSI:[Amim] Cl (14:6:80 wt%). The improving trend in ionic conductivity results from the bond weakening between the connecting atoms in the crystalline region that induces to the increase in amorphous counterpart fractions in the CA matrix. This observation was proved via the accountancies in the reduction of relative viscosity, root mean square value and increase in void as increase in [Amim] Cl doping. The resultant phase conversion hence permits immense lithium ion (Li+) fluidity along the polymer backbone and assisting the improvement in ionic conductivity. The thin film polymer electrolyte is found to be elastic in the presence of crystalline fraction and radically deforms upon the chains diffusion into the amorphous fraction. The linear curvatures of the Arrhenius plot justify the conductivity improvement as via the increasing frequency of Li+ ions hopping as the temperature increases. The increasing addition of [Amim] Cl diminishes both the heat-resistivity and thermal stability of CA:LiTFSI:[Amim] Cl matrix.

A novel PEO-based composite polymer electrolyte with NaAlOSiO molecular sieves powders

Ion-conducting thin film polymer electrolytes based on poly(ethylene oxide) (PEO) complexes with NaAlOSiO molecular sieves powders has been prepared by solution casting technique. X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and alternating current impedance techniques are employed to investigate the effect of NaAlOSiO molecular sieves on the crystallization mechanism of PEO in composite polymer electrolyte. The experimental results show that NaAlOSiO powders have great influence on the growth stage of PEO spherulites. PEO crystallization decrease and the amorphous region that the lithium-ion transport is expanded by adding appropriate NaAlOSiO, which leads to drastic enhancement in the ionic conductivity of the (PEO)16LiClO4 electrolyte. The ionic conductivity of (PEO)16LiClO4-12 wt.% NaAlOSiO achieves (2.370 ± 0.082) × 10−4 S · cm−1 at room temperature (18 °C). Without NaAlOSiO, the ionic conductivity has only (8.382 ± 0.927) × 10−6 S · cm−1, enhancing 2 orders of magnitude. Compared with inorganic oxide as filler, the addition of NaAlOSiO molecular sieves powders can disperse homogeneously in the electrolyte matrix without forming any crystal phase and the growth stage of PEO spherulites can be hindered more effectively.

Electrical and structural studies on (PEO)50-AgCF3SO3: SnO2 nanocomposite gel polymer electrolyte materials

The present work deals with a new series of silver-ion conducting nanocomposite gel polymer electrolytes based on poly (ethylene oxide)50silver triflate, (PEO)50AgCF3SO3 incorporated with a nano-sized inorganic filler namely, SnO2 and a plasticizer, ethylene carbonate (EC) prepared using solution casting technique. Electrical conductivity measurements have been made on thin film polymer electrolyte systems containing (PEO50AgCF3SO3: 2wt% SnO2) + x wt% EC (x = 10, 15, 20, 25 and 30 respectively). It has been found that the room temperature ionic conductivity value enhanced from 3.1 × 10−6 to 5.4 × 10−5 S cm−1 on addition of EC into the chosen nanocomposite system PEO50AgCF3SO3: 2wt% SnO2. The apparent surface morphology has been examined through scanning electron microscopic (SEM) analysis. The occurrence of a reduction in the degree of crystallinity of the plasticized system has also been revealed from the observed X-ray diffraction (XRD) data.

Validated Leverett Approach for Multiphase Flow in PEFC Diffusion Media: III. Temperature Effect and Unified Approach

The final paper in this series is devoted to delineating the effects of temperature on the multiphase transport characteristics of thin-film polymer electrolyte fuel cell (PEFC) diffusion media (DM). Direct measurements of capillary pressure-saturation of various commercial DM coated with a wide range of poly(tetrafluoroethylene) (PTFE) loadings (from 5 to PTFE) were performed at different operating temperatures (20, 50, and ). The benchmark data gathered from these experiments (available upon request) were compiled into the existing database generated from the first and second phase of this study, which examined the hydrophobicity and compression effects. The expanded database was then utilized to deduce a unified form of an empirical correlation appropriate for the tested DM. This semiempirical approach can predict capillary pressure of the tested DM as a function of liquid saturation, hydrophobic additive content, uncompressed porosity, compression pressure, and operating temperature within an uncertainty of of the measured capillary pressure over the entire saturation domain, showing considerable improvement over the traditional Leverett approach.

Validated Leverett Approach for Multiphase Flow in PEFC Diffusion Media: II. Compression Effect

This work is the second part of a series of papers to describe the multiphase transport mechanism in thin-film polymer electrolyte fuel cell (PEFC) diffusion media (DM). The present work is devoted to delineating the effects of compression. Direct measurements of drainage capillary pressure-saturation curves for SGL series carbon paper DM tailored with a range of mixed wettability were performed at room temperature under various compressions (0, 0.6, and ) typically encountered in a fuel cell assembly. Based on these benchmark data, an appropriate form of the Leverett approach, including a Leverett-type empirical function that incorporates the effect of compression and the mixed wettability characteristics of the tested DM samples, was developed. The presented approach can determine the capillary pressure as a function of hydrophobic additive content, liquid saturation, compression, and uncompressed porosity of the DM. Compression leads to an increase in capillary pressure, effectively caused by the corresponding reduction in effective porosity. Any increase in hydrophobicity amplifies the compression effect, yielding a higher capillary pressure for the same saturation level. Furthermore, the fraction of connected hydrophilic pores is observed to be reduced with an increase in compression, leading to a favorable reduction in water storage capacity of the fuel cell DM.

Conductivity study of polyethylene oxide (PEO) complexed with sodium bicarbonate

Ion conducting thin film polymer electrolytes based on polyethylene oxide (PEO) complexed with NaHCO3 salt has been prepared using solution-cast technique. The complexation of NaHCO3 salt with PEO is confirmed by XRD and IR studies. DC conductivity in the temperature range 303–368 K has been evaluated. The conductivity is found to increase in the PEO complex with the NaHCO3 salt and also with an increase in temperature. Using this polymer electrolyte, an electrochemical cell with the configuration Na/(PEO + NaHCO3)/(I2 + C + electrolyte) has been fabricated and its discharge characteristics studied. Open Circuit Voltage (OCV) and Short Circuit Current (SCC) are found to be 2.69 V and 1.28 mA, respectively. Other parameters associated with the cell are evaluated and presented in this paper.

New composite solid electrolytes based on a polymer and ionic liquids

A series of ion-conducting, thin-film polymer electrolytes, based on a polymer (poly(acrylonitrile) [PAN], poly(ethyleneoxide) [PEO] and poly(vinylalcohol) [PVA]), and ionic liquids (IL), polymer–IL, as well as ternary systems PAN–IL–TMS were prepared using the casting technique (TMS is sulpholane, ionic liquids are: 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethane sulfonyl)imide). The polymer electrolytes showed a rubber-like elasticity. Maximum conductivity was at the level of 15 mS/cm at room temperature. The electrochemical stability window of the electrolytes, determined at the glassy carbon electrode, was of ca. 3 V.

New polymer electrolyte poly(acrylonitrile)–sulpholane–(C 2H 5) 4NBF 4 for chemical capacitors

A series of ion conducting, thin-film polymer electrolytes, based on poly(acrylonitrile), tetraethylammonium tetrafluoroborate and sulpholane (tetramethylene sulphone, TMS), PAN–(C 2H 5) 4NBF 4–TMS, were prepared using the casting technique. The polymer electrolytes were transparent with rubberlike elasticity. Maximum conductivity was at the level of 10 mS/cm at room temperature. The temperature dependence of the conductivity indicates the Arrhenius type of the behaviour, with the activation energy of 12 kJ/mol. The electrochemical stability window of the electrolyte, determined at the glassy carbon electrode, was of ca. 3 V. Capacitor electrodes, in the form of thin foils, were prepared by the casting technique, using activated carbon powder (ACP) mixed with acetylene black (AB) or graphite (G) as an electrode active material. The performance of capacitors, having a coin-like shape, a diameter of 18 mm and a mass of 180–350 mg, was determined by cyclic voltammetry, impedance spectroscopy and galvanostatic charging and discharging.

Preparation and characterization of a new polymer electrolyte (PEO:NaClO3) for battery application

A new sodium-ion conducting thin-film polymer electrolyte based on the poly(ethylene oxide) (PEO) system has been prepared by a solution-casting method. Characterization by XRD, IR, and AC conductivity and Wagner's polarization were carried out on these thin-film electrolytes. From the transference number experiment it was found that the charge transport in these electrolytes is mainly due to ions. Conductivity studies show that the conductivity value of the PEO:NaClO3 complex increases with the increase of salt concentration. An increase in the conductivity and a change in the cell parameters for the electrolyte system were found by the addition of the low molecular weight dimethylformamide or propylene carbonate as plasticizers. The cell parameters of these electrolyte systems were measured from a discharge study of the cell with the application of a load of 100 kΩ at room temperature in the common cell configuration Na|electrolyte|MnO2. The open circuit voltage ranges from 2.02 V to 2.46 V and the short circuit current ranges from 570 µA to 1030 µA.

Study of a new polymer electrolyte poly(ethylene oxide): NaClO3 with several plasticizers for battery application

Sodium ion conducting thin film polymer electrolytes based on poly(ethylene oxide) (PEO) complexed with NaClO3 were prepared by a solution-casting method. Characterization by XRD, IR spectroscopy and AC conductivity has been carried out on these thin film electrolytes to analyse their properties. The conductivity studies show that the conductivity value of PEO:NaClO3 complex increases with the increase in salt concentrations. Increase in conductivity was found in the electrolyte system by the addition of low molecular weight polymer poly(ethylene glycol) (PEG) and the organic solvents dimethylformamide (DMF) and propylene carbonate (PC). Using these electrolyte systems, cell parameters were measured from the discharge study with the application of load 100 kΩ at room temperature with common cell configuration Na|electrolyte|C:I2:electrolyte. The open circuit voltage (OCV) ranges from 2.81 to 3.23 V and the short circuit current (SCC) ranges from 340 to 1180 µA. © 2001 Society of Chemical Industry

A new PEO-based thin film polymer electrolyte complexed with KYF4, and its application as an electrochemical cell

A new PEO-based thin film polymer electrolyte complexed with KYF4, and its application as an electrochemical cell

Fabrication and discharge characteristics of thin film polymer electrolyte cells

Abstract Electrochemical cells, designed for incorporation into integrated circuits, have been fabricated using thin film deposition techniques. The cells, based on the Liƒ(PEO)8LiClO4ƒV2O5 system, are approximately 5 μm thick. Interpretation of the discharge characteristics indicates that diffusion-limiting behaviour is present in the polymeric electrolyte at discharge currents above 25 μA cm−2.

Interfaces between electronically and ionically conducting polymers: Applications to ultra high-vacuum electrochemistry and photoelectrochemistry

Interfaces between ionically conducting polymers as solid electrolytes and electronically conducting polymers as electrode materials are discussed both from the point of view of fundamental materials studies and the device potential of the structures. A new technique has been developed that allows both electrochemical synthesis and reduction/oxidation of conducting polymers in situ in ultra-high vacuum using thin-film polymer solid electrolytes, concurrent with the application of photoelectron spectroscopy techniques. Interfaces between thin-film polymer electrolytes and conducting polypyrole are also shown to have potential applications in photoelectrochemistry.