Methanol electrooxidation on platinum mesh electrodes bonded to solid polymer electrolytes

Methanol electrooxidation on smooth platinum electrodes bonded to solid polymer electrolytes was studied in water and acid solution by voltammetric measurements with different scanning rates. An enhancement of the oxidation rates was observed in these systems as compared to identical platinum electrodes in contact with liquid electrolytes. This electrocatalytic effect strongly depends on the measuring conditions and on the electrode potential. The reasons for the catalytic effects at different potentials are discussed. Received: 8 January 1997 / Accepted: 1 December 1997     

Catalytic phenomena during the methanol oxidation at platinum electrodes in contact with solid polymer electrolytes

The methanol electrooxidation at platinum-gauze electrodes contacting a solid polymer electrolyte is studied in water and sulfuric-acid solutions by voltammetry in a broad potential range and by measuring steady-state currents and electrode coverages with chemisorbed species at low anodic potentials. The specific rate of the methanol oxidation in these systems is higher than that of similar platinum electrodes in liquid electrolytes. The catalytic action depends on the measurements conditions and the electrode potential. Reasons for catalytic effects at different potentials are discussed.     

Borate ester plasticizer for PEO-based solid polymer electrolytes

Lithium rechargeable batteries featuring solvent-free highly conductive solid polymer electrolytes (SPEs) will make a dramatic impact on the electric and hybrid-electric vehicles (EV/HEV) industry by eliminating hazards related to the use of liquid electrolytes. In this paper, we report the synthesis and characterization of a star-shaped borate ester plasticizer, which was then incorporated into the poly(ethylene oxide) polymer matrix in different proportions. Significant improvement was observed in conductivity, with the best value of 9.1 × 10⁻⁵ S/cm at 30 °C. These borate ester plasticized SPEs also exhibited excellent thermal and electrochemical stabilities.     

Ionic IPNs as novel candidates for highly conductive solid polymer electrolytes

Five ionic imidazolium based monomers, namely 1‐vinyl‐3‐ethylimidazolium bis(trifluoromethylsulfonyl)imide (ILM1), 1‐vinyl‐3‐(diethoxyphosphinyl)‐propylimidazolium bis(trifluoromethylsulfonyl)imide (ILM2), 1‐[2‐(2‐methyl‐acryloyloxy)‐propyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM3), 1‐[2‐(2‐methyl‐acryloyloxy)‐undecyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM4), 1‐vinyl‐3‐ethylimidazolium dicyanamide (ILM5) were prepared and used for the synthesis of linear polymeric ionic liquids (PILs), crosslinked networks with polyethyleneglycol dimethacrylate (PEGDM) and interpenetrating polymer networks (IPNs) based on polybutadiene (PB). The ionic conductivities of IPNs prepared using an in situ strategy were found to depend on the ILM nature, T_g and the ratio of the other components. Novel ionic IPNs are characterized by increased flexibility, small swelling ability in ionic liquids (ILs) along with high conductivity and preservation of mechanical stability even in a swollen state. The maximum conductivity for a pure IPN was equal to 3.6 × 10^?5 S/cm at 20 °C while for IPN swollen in [1‐Me‐3‐Etim] (CN)₂N σ reached 8.5 × 10^?3 S/cm at 20 °C or 1.4 × 10^?2 S/cm at 50 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4245–4266, 2009     

23Na NMR in urethane cross-linked polyether solid polymer electrolytes

Sodium triflate/polyether urethane polymer electrolytes ranging in concentration from 0.05 molal to 1.75 molal have been investigated via ²³Na static solid-state NMR. Room temperature spectra and spin lattice relaxation times were consistent with a single narrow resonance indicating the presence of only mobile ionic species. The concentration and temperature dependence of relaxation times, chemical shifts, and linewidth have been investigated. The results suggest either a single species or rapid exchange between a number of species (even at temperatures below the glass transition temperature, T_g). The linewidth decreases with increasing concentration of ions and remains temperature independent below T_g. Below T_g a maximum quadrupolar interaction constant of 2 MHz is calculated. The addition of plasticizer to the polymer electrolyte causes significant chemical shift changes that depend on the solvent donicity of the plasticizer. The linewidth and T₁ relaxation times also depend on the T_g of the plasticized systems. Previous ²³Na NMR literature results are reviewed and qualitative models developed to account for the variation in results. © 1994 John Wiley & Sons, Inc.     

Adaptation of electrodes and printable gel polymer electrolytes for optimized fully organic batteries

Despite intensive scientific efforts on the development of organic batteries, their full potential is still not being realized. The individual components, such as electrode materials and electrolytes, are in most cases developed independently and are not adjusted to each other. In this context, we report on the performance optimization of a full-organic solid-state battery system by the mutual adaptation of the electrode materials and an ionic liquid (IL)-based gel polymer electrolyte (GPE). The formulation of the latter was designed for a one-step manufacturing approach and can be applied directly to the electrode surface, where it is UV-cured to yield the GPE without further post-treatment steps. Herein, a special focus was placed on the applicability in industrial processes. A first significant capacity increase was achieved by the incorporation of the IL into the electrode composite. Furthermore, the GPE composition was adapted applying acrylate- and methacrylate-based monomers and combinations thereof with the premise of a fast curing step. Furthermore, the amount of IL was varied, and all combinations were evaluated for their final performance in cells. The latter variation revealed that a high ionic conductivity is not the only determining factor for a good cell performance. Next to a sufficient conductivity, the interaction between electrode and electrolyte plays a key role for the cell performance as it enhances the accessibility of the counter ions to the redox-active sites.     

Dye-sensitized solar cells based on composite solid polymer electrolytes

The ionic conductivity of polymer electrolytes and their interfacial contact with dye-attached TiO2 particles were enhanced markedly by the addition of amorphous oligomer into polymer electrolytes, resulting in very high overall energy conversion efficiency.     

Scalable fabrication of sheet-type electrodes for practical all-solid-state batteries employing sulfide solid electrolytes

The limited safety and energy density of conventional lithium-ion batteries have triggered the research and development of all-solid-state Li or Li-ion batteries (ASLBs). Sulfide solid electrolytes possess the remarkable advantages combining high ionic conductivity and mechanical deformability that allows for simple cold-pressing based fabrication of the cells. For this reason, these electrolytes find promising application in practical ASLBs. However, the large gap between experimental laboratory research and practical applications poses a formidable challenge. Herein, recent studies on scalable fabrication strategies for ASLBs employing sulfide solid electrolytes are discussed. The critical factors for wet-slurry and dry-film fabrication methods are reviewed. Based on these results, recent developments in slurry-processing solvents, polymeric binders, and fabrication protocols are summarized. Finally, the advantages and disadvantages of the two fabrication protocols are summarized, along with prospects for future research.     

Polymerization-induced microphase separation of polymer-polyoxometalate nanocomposites for anhydrous solid state electrolytes

Solid-state electrolytes (SSEs) with high ionic conductivity, mechanical stability, and high thermal stability, as well as the stringent requirement of application in high-temperature fuel cells and lithium-ion batteries is receiving increasing attention. Polymer nanocomposites (PNCs), combining the advantages of inorganic materials with those of polymeric materials, offer numerous opportunities for SSEs design. In this work, we report a facile and general one-pot approach based on polymerization-induced microphase separation (PIMS) to generate PNCs with bi-continuous microphases. This synthetic strategy transforms a homogeneous liquid precursor consisting of polyoxometalates (POMs, H₃PW₁₂O₄₀, Li₇[V₁₅O₃₆(CO₃)]), poly(ethylene glycol) (PEG) macro-chain-transfer agent, styrene and divinylbenzene monomers, into a robust and transparent monolith. The resulting POMs are uniformly dispersed in the PEG block (PEG/POM) to form a conducting pathway that successfully realizes the effective transfer of protons and lithium ions, while the highly cross-linked polystyrene domains (P(S-co-DVB)) as mechanical support provide outstanding mechanical properties and thermal stability. As the POM loading ratio up to 35 wt%, the proton conductivity of nanocomposite reaches as high as 5.99 × 10^-4 S/cm at 100 °C in anhydrous environment, which effectively promotes proton transfer under extreme environments. This study broadens the application of fuel cells and lithium-ion batteries in extreme environments.     

Recent progress of composite solid polymer electrolytes for all-solid-state lithium metal batteries

In comparison with lithium-ion batteries (LIBs) with liquid electrolytes, all-solid-state lithium batteries (ASSLBs) have been considered as promising systems for future energy storage due to their safety and high energy density. As the pivotal component used in ASSLBs, composite solid polymer electrolytes (CSPEs), derived from the incorporation of inorganic fillers into solid polymer electrolytes (SPEs), exhibit higher ionic conductivity, better mechanical strength, and superior thermal/electrochemical stability compared to the single-component SPEs, which can significantly promote the electrochemical performance of ASSLBs. Herein, the recent advances of CSPEs applied in ASSLBs are presented. The effects of the category, morphology and concentration of inorganic fillers on the ionic conductivity, mechanical strength, electrochemical window, interfacial stability and possible Li⁺ transfer mechanism of CSPEs will be systematically discussed. Finally, the challenges and perspectives are proposed for the future development of high-performance CSPEs and ASSLBs.     

New solid polymer electrolytes based on polyester diacrylate for lithium power sources

New solid polymer electrolytes are developed for a lithium power source used at the temperatures up to 100°C. Polyester diacrylate (PEDA) based on oligohydroxyethylacrylate and its block copolymers with polyethylene glycol were offered for polymer matrix formation. The salt used was LiClO₄. The ionic conductivity of electrolytes was measured in the range of 20 to 100°C using the electrochemical impedance method. It is shown that the maximum conductivity in the whole temperature range is characteristic of the electrolyte based on the PEDA copolymer and polyethylene glycol condensation product (2.8 × 10^?6 S cm^?1 at 20°C, 1.8 × 10^?4 S cm^?1 at 95°C).     

固态聚合物电解质的锂离子传导机理与研究进展

锂离子电池(lithiumionbatteries,LIBs)在储能领域已取得了巨大的成功.然而,商用LIBs含有高挥发性易燃有机电解液,使其存在严重的安全隐患.固态聚合物电解质具有解决相应安全性问题的潜力,有望成为下一代高安全性全固态LIBs的电解质材料.然而,固态聚合物电解质存在离子电导率不高等问题,限制了其在固态LIBs中的实际应用.研究者们为了提高该类电解质的离子电导率、锂离子迁移数等综合电化学性能,已在寻找新锂盐、对聚合物进行改性以及向聚合物电解质中添加填料等方面进行了较多的研究.本文简要概述了固态聚合物电解质的锂离子传导机理以及在提高固态聚合物电解质综合电化学性能方面的研究进展.     

Alternative reference system in the thermodynamics of solid elastic electrodes

Basic quantities in the thermodynamics of the solid elastic electrode are the surface tension tensor g _mn and the work needed for the formation of the surface (interface) γ. It is scarcely mentioned explicitly anywhere that these intensive (specific) quantities are related to the surface of the elastically deformed electrode. On the other hand, in the thermodynamics of the volume elasticity, the free energy density of the deformed solid is related to the volume of the undeformed solid. In this paper, we introduce equivalently the undeformed surface of the solid elastic electrode as reference for both the surface tension tensor and the work of formation of the surface. Generalizing the analysis of two model systems, we deduce the corresponding alternative form of the Shuttleworth equation, where the two quantities appear as generalized force and generalized potential, and discuss consequences for the formulation of the differential of the surface excess of the internal energy.Dedicated to the memory of W. Schwabe     

Quantum mechanical insight into the Li-ion conduction mechanism for solid polymer electrolytes

Ion transport in polymeric electrolytes (PEs) has been studied for approximately a half century, yet the ion conduction mechanism in the PEs is not fully understood. Herein, we report a new approach to understand the ion migration process in poly (ethylene oxide)/Lithium bis(trifluoromethane sulphonyl) imide (PEO/LiTFSI) and poly (ethylene oxide)/Lithium bis(oxalate) borate (PEO/LiBOB) electrolytes based on quantum mechanics. The results show that the coefficient of determination (R²) obtained from the new model exceeds 0.99 for all the PEs, which is far higher than these obtained from the well-known Arrhenius and Vogel-Tammann-Fulcher (VTF) equations. The wavelength (λ_Li+) of Li-ion migrations or the distance between the occupied site and the neighboring partially-occupied site is the most crucial factor to affect the ionic conductivity of PEs. The higher the λ_Li+, the better the ionic conductivity. The maximum λ_Li+ value of the PEs approximates angstrom order of magnitude. The developed ion conduction model opens an avenue to design PEs with a higher ionic conductivity.     

Characteristics of reference electrodes using a polymer gate ISFET

A new type of ISFET with a Parylene gate as a site-free and ion-blocked membrane has been proposed for a reference electrode. The reference ISFET should be insensitive to the variation of ion concentrations of all ions or a specific ion in the electrolyte and should have a constant gate surface potential. In this paper, the operation of this reference ISFET is analysed by the site binding model and the conditions required to make the gate surface potential constant are examined. In general, the surface potential of an electrolyte-insulator-semiconductor (EIS) system is determined by two factors, i.e., the available surface site density of the insulator and the total charge density of the semiconductor, and it can be made constant by controlling the total charge density of the semiconductor. The preliminary experimental results on the electrolyte-Parylene-Si diode and ISFET are in good agreement with the theoretical calculations and suggest that a reference ISFET could be realized by using the Parylene gate.     

Development of ion-conducting polymer electrolytes for use in high-energy lithium rechargeable batteries

Polymers based on poly(thylene oxide) (PEO) are a very promising new type of stable electrolytes for lithium rechargeable batteries. Their relatively low ionic conductivities can be more than compensated by the very small electrolyte thicknesses that can be used. Specific energies of 100 Wh/kg at sustained specific powers of 70 W/kg, have been obtained at Hydro-Québec with 100 μm of PEO electrolyte at 100°C. In an electric vehicle, this would give a driving range of over 300 km at 80 km/h, more than three times as much as lead-acid batteries. PEO-related polymers have been developed for lower temperature applications such as computers or portable appliances. Advantages over competitive Ni-Cd batteries are higher energy densities and absence of self-discharge, with expected shell lifes of 10 years. Laboratory prototypes (3600 cm², 10 Wh) demonstrate the absence of scale-up effects and excellent cycling capability (over 300 charge-discharge cycles).     

Fabrication of new solid state phosphate selective electrodes for environmental monitoring

A highly selective and sensitive phosphate sensor has been fabricated by constructing a crystal disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO₄) and powdered copper (Cu). The membrane sensor exhibits linear potential response in the concentration range of 1.0 × 10⁻¹ to 1.0 × 10⁻⁶ mol L⁻¹. The proposed sensor also exhibits a fast response time of <60 s. Its detection limit is lower than 1.0 × 10⁻⁶ mol L⁻¹. The electrode has a long lifetime and can be stored in air when not in use. The selectivity of the sensor with respect to other common ions is excellent.     

Preparation and characterization of pva based solid polymer electrolytes for electrochemical cell applications

Solid polymer electrolyte films containing poly(vinyl alcohol) (PVA) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303 383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/(PVA + Mg(NO3)2) (70:30)/(I2 + C + electrolyte) has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.     

Effect of oleic acid plasticizer on chitosan-lithium acetate solid polymer electrolytes

Plasticized polymer electrolytes composed of chitosan as the host polymer, oleic acid (OA) as the plasticizer and lithium acetate (LiOAc) as the doping salt were prepared by the solution cast technique. These complexes with different amounts of salts and plasticizers were investigated as possible ionic conducting polymers. The highest ionic conductivity of the plasticized chitosan-LiOAc was ∼10⁻⁵ S cm⁻¹ for the film containing 40.0 wt.% LiOAc and 10.0 wt.% of OA. Conductivity for the plasticized LiOAc-doped chitosan polymer was also studied as a function of temperature between 300 and 363 K. The plot of ln(σT) versus 10³/T for each sample obeys Arrhenius rule indicating the conductivity to be thermally assisted. XRD and FTIR spectroscopy techniques have been used for the structural studies.