Solid-state Electrolyte Membranes Research Articles

Solid electrolyte membranes prepared from poly(arylene ether sulfone)-g-poly(ethylene glycol) with various functional end groups for lithium-ion battery

A series of poly(arylene ether sulfone)-g-poly(ethylene glycol)s (PAES-g-PEG)s with different functional groups of –CH3, –OH, -2OH, and –CN were synthesized for the application of solid polymer electrolyte membranes in the lithium-ion battery. Several essential material and membrane properties, including thermal, mechanical, dimensional stability, lithium-ion conductivity, interfacial compatibility, Li-ion transference number, and cell performance, were investigated. The phase separation behavior in the presence of ionic liquid was also examined using small-angle X-ray scattering. As this provision of functional groups led to the suppression of crystallinity but the increment of dielectric permittivity of the electrolytes, both the lithium-ion conductivity and Li-ion transference number were significantly affected. Among them, the PAES-g-PEG membrane containing –CN end group showed the highest lithium-ion conductivity of 8.97 × 10−4 S cm−1 and the Li-ion transference number of tLi+ = 0.4, maintaining the rigid solid-state with the tensile strength beyond 1.5 MPa at room temperature. These excellent physical and electrochemical properties of solid-state electrolyte membranes led to quite a high cell capacity of over 138 mAh g−1 during the 50 charge-discharge cycling tests and stable lithium stripping/plating cyclic performance during 500 cycles.

Tailoring grain growth and densification toward a high-performance solid-state electrolyte membrane

The synthesis of dense and uniform solid-state electrolyte membranes for Li batteries is challenging due to the lack of fine control over the grain growth by conventional sintering methods. Using such techniques, abnormal grain growth can often occur, with associated contaminants and voids, often resulting in electrolyte membranes that suffer from high resistivity, poor stability, and the risk of Li dendrite penetration. Herein, we report a new high-temperature (1500 K) and rapid sintering (30 s) process by Joule heating that tailors the grain growth and densification toward high-quality, high-performance solid-state electrolyte membranes. The high temperature contributes to the rapid removal of impurities, leading to a dense and uniform microstructure in seconds. The short sintering time provides controlled grain growth, with nearly unchanged grain size and distribution compared to the solid-state electrolyte powders prior to sintering. Using calcined Ta-doped Li7La3Zr2O12 (LLZTO) garnet powders, we show that the grain size distribution before and after the rapid sintering are nearly identical (∼4 μm for both), while defects (e.g., voids and gaps) and impurities are effectively eliminated. The resulting high-quality membrane features good ionic conductivity (6.4 × 10−4 S cm−1 at room temperature) and excellent stability during lithium striping/plating (>300 h under 0.2 mA cm−2), making it suitable for Li battery applications. This high-temperature rapid sintering approach can be further extended to a variety of ceramic Li+ conductors toward the future development of solid-state batteries.

Long-term durable solid state electrolyte membranes based on a metal–organic framework with phosphotungstic acid confined in the mesoporous cages

In this study, phosphotungstic acid-encapsulated MIL-101 (Fe) (HPW@MIL-100 (Fe)) was synthesized by the in-situ direct hydrothermal method. Due to the large mesoporous cages and small microporous windows of MIL-100 (Fe), HPW could be well loaded and confined in the cages of MIL-100 (Fe). Furthermore, novel hybrid proton exchange membranes were fabricated by incorporating HPW@MIL-100 (Fe) into sulfonated poly (arylene ether ketone sulfone) containing carboxyl groups (C-SPAEKS) matrix. The structures of MIL-100 (Fe), HPW@MIL-100 (Fe), C-SPAEKS, and hybrid membranes were characterized by XRD and FT-IR. The HPW@MIL-100 (Fe), with a large amount of phosphotungstic acid in cages, could enhance the proton conductivities of hybrid membranes. The hybrid membrane with 4% content of HPW@MIL-100 (Fe) achieved a high proton conductivity of 0.072 S cm−1 at 80 °C and 100% relative humidity, which was 1.8 times higher than that of pure C-SPAEKS (0.040 S cm−1) at the same conditions. Meanwhile, the introduced HPW@MIL-100 (Fe) fillers improved the dimensional stability of hybrid membranes. These results indicate that introduction of MIL-100 (Fe) materials loaded with HPW plays an important role in improving the comprehensive performance and this series of hybrid membranes have potential as proton exchange membranes.

A flexible composite electrolyte membrane with ultrahigh LLZTO garnet content for quasi solid state Li-air batteries

As an alternative next-generation energy storage device, solid state Li-air battery is generally investigated due to its high energy density and safety, yet the suitable solid state electrolyte and big overpotential issues hinder its application. Herein, we develop a novel flexible composite solid state electrolyte membrane with an ultrahigh LLZTO garnet content of ~89.6 wt% (LLZTO CMs) via a facile tap casting/phase-inversion process and a simple solution infiltration method. After introducing [Li∈12-C-4][I] supramolecular filler, LLZTO CMs exhibits high ionic conductivity of 6.92 × 10−4 S cm−1 at 20 °C and 2.85 × 10−3 S cm−1 at 80 °C, outstanding compatibility with Li metal and acceptable capability against Li dendrites. When pouch quasi solid state Li-air batteries are assembled with commercial carbon cloth (without any electrocatalysts) as oxygen electrode, a lower discharge-charge voltage gap of ~600 mV and an inspired cycling stability are obtained. This study suggests that LLZTO CMs could open a new avenue for developing advanced solid state Li-air batteries.

A Solid-State and Flexible Supercapacitor That Operates across a Wide Temperature Range

Electrochemical properties of most supercapacitor devices degrade quickly when the operating temperature deviates from room temperature. To exploit the potential of rGO in supercapacitors at extreme temperatures, a resilient electrolyte that is functional over a wide temperature range is also required. In this study, we have implemented a flexible, low-resistant solid-state electrolyte membrane (SSEM) into symmetric rGO electrodes to realize supercapacitor devices that operate in the temperature range −70 to 220 °C. The SSEM consists of a polycation–polybenzimidazole blend that is doped with phosphoric acid (H3PO4), and this material displays uniquely high conductivity values that range from 50 to 278 mS cm–1 in the temperature range −25 to 220 °C. The fabricated supercapacitor produced a maximum capacitance of 6.8 mF cm–2 at 100 °C. Energy and power densities ranged from 0.83 to 2.79 mW h cm–2 and 90 to 125 mW cm–2, respectively. The energy storage mechanism with a SSEM occurs by excess H3PO4 migrating from the membrane host into the electrochemical double layer in rGO electrodes. The high-temperature operation is enabled by the polycation in the SSEM anchoring phosphate type of anions preventing H3PO4 evaporation. Low-temperature operation of the supercapacitor with the SSEM is attributed to the PC–PBI matrix depressing the freezing point of H3PO4 to maintain structural proton diffusion.

Flexible Garnet Solid-State Electrolyte Membranes Enabled by Tile-and-Grout Design

Inorganic solid-state electrolytes for lithium metal batteries have attracted significant interest, but their brittle nature creates a severe hurdle to widespread application in flexible electronics. Herein, we propose the rational design of a flexible electrolyte membrane with a tile-and-grout pattern in which garnet-type electrolyte tile-like chips are joined together without gaps by styrene–butadiene copolymer using additive manufacturing. The dimensions of the garnet chips are optimized through fracture mechanics analysis, which effectively suppresses the strain energy below the fracture toughness of the garnet solid-state electrolyte, eliminating random cracking. The garnet chips function as fast lithium-ion transport channels, while the styrene–butadiene copolymer grid serves as a deformable buffer to further reduce the stress transferred to the garnet chips. The tile-and-grout design electrolyte membrane presents good flexibility and can be readily bent without breaking. Our facile and pragmatic st...

Surface-Engineered Boron Nitride Electrolytes for High Performance Solid-State Supercapacitors

In the modern era of smart wearable electronics and compact transportation systems, there is an urge for the development of solid, lightweight, flexible and efficient energy storage devices. For realizing high performance energy devices, novel electrolyte materials with high energy density at enhanced power are demanding. The recent developments in the field of two-dimensional (2D) materials, including graphene, 2D hexagonal boron nitride (2D-hBN) and transition metal dichalcogenides, have exhibited promise for a wide range of applications. In particular, 2D-hBN, also known as “white graphene” is an isomorph of graphene with similar layered structure in a hexagonal lattice, which is uniquely featured by its exotic opto-electrical properties together with mechanical robustness, thermal stability, and chemical inertness. Due to its remarkable electrochemical properties, it is considered as a promising candidate that can be integrated with other 2D materials, for the next generation electrochemical energy storage and conversion applications including fuel cells, batteries and supercapacitors Moreover, h-BN possess electrically insulating behavior at wide range of humidity and temperatures, which makes it more versatile to be manipulated and used as an electrolyte membrane in electrochemical energy systems. In order to realise hBN nanosheets (BNNS) potential as an ion-conductive solid electrolyte in advanced energy devices, scalable production techniques involving simple and efficient green synthesis routes are crucially required. Liquid phase exfoliation and ball milling are versatile techniques for the production of large-scale, defect-free, few-layered 2D materials. Further, steps of chemical functionalization are involved to produce surface-engineered BNNS solid-state electrolyte membranes with high ionic conductivity and durability, for electrochemical energy storage technologies. In this project, the solvent-assisted exfoliation method has been employed to produce few-layered BNNS. In this method a polar solvent with similar surface energy to that of BNNS (e.g. organic solvents such as DMF, or acids) is used to cleave BNNS through ultrasonication energy to produce few-layered, stable dispersions of BNNS. Then, high surface area of BNNS was engineered with ion-conductive groups enabling the transfer of ions (e.g., H+). The augmentation of BNNSs significantly improved their ion-conductivity and electrochemical stability properties through covalent and non-covalent bonding with the hexagonal BN network. As a result, significant enhancement in both of in-plane and through-plane ion-conductivity was observed at different operating conditions (e.g., 0.34 S/cm at 25 °C and 50% relative humidity). The surface-engineered BNNS materials acted as high-performance solid electrolyte membranes in solid-state supercapacitors. In addition to electrochemical measurements, microscopic, spectroscopic and structural characterization tests were applied to investigate the chemical and surface structures, surface functionalization mechanism, the ion-conductivity mechanism, and physical properties of the developed BNNS.

Electrochemical preparation of standard gas mixtures using solid-state electrolyte membrane

A novel electrochemical method of preparation of standard gas mixtures for calibration of gas-analytical equipment with O2, H2 and CO was elaborated. Utilization of solid state electrolyte membrane allows to perform a nearly 100%-efficient electrochemical generation or conversion of the analyte and avoid some problems typical for liquid electrolytes, such as solvent evaporation and condensation at the inner walls of the gas tubes or deviations from the Faraday’s law. Analysis of uncertainties associated with the calibration procedure showed that the lowest systematic errors are achieved when the calibrant is generated during the electrolysis (i.e. anodic evolution of oxygen or cathodic generation of CO), and the major uncertainties are associated with operation of the flow controllers. For calibration with H2, where the calibrant is partially converted during the electrochemical process, the total uncertainty is essentially determined by molar fractions of the components in H2-Ar mixture, instrumental errors of the equipment, primarily by precision of mass-flow controllers or stability of the gas flow, and the initial flow rate of the calibrant-containing gas mixture. The relative total errors of calibration with oxygen are assessed to be 5–6%; similar uncertainties were calculated for analysis of oxygen content in standard gas mixtures by chromatography using the electrochemical method of calibration.

The Next Chapter in the Hybrid Eutectogel Electrolytes

Lithium-ion batteries are the energy storage devices of choice not only for portable devices but electric vehicles and grid energy storage as well due to their high gravimetric and volumetric energy density. Their ancestors, the lithium metal batteries offer way higher capacities but suffered severely from safety issues due to the dendrite formation. Solid state electrolytes; e.g. LISICON, garnets, perovskites, etc.; may mitigate this risk but suffer from low ionic conductivity (<10-4 S/cm). [1] The interfacial resistance between the electrode and the solid electrolyte is also very challenging. Hybrid solid state electrolytes can address these issues and allow for an easier implementation into conventional battery technology. The hybrid solid state electrolyte combines the desirable properties of both liquid and solid electrolytes by confining liquid electrolytes within a (meso-)porous solid framework.[2,3] This approach allows to maintain the high ionic conductivity and intimate contact with the electrodes while offering the safety of solid electrolytes. Our group developed the eutectogels in which a deep eutectic electrolyte (binary mixture of N-methylacetamide and LiTFSI) is confined within a porous silica framework designed via a facile one-pot non-aqeous sol-gel route.[4] This hybrid electrolyte can act as a greener and cheaper alternative to the well-known ionogels.[5] The eutectogels offer a broad electrochemical window, with a beneficial anodic stability limit of up to 4.8 V vs Li+/Li while impedance spectroscopy revealed ionic conductivities of up to 1.46 mS/cm at room temperature for the optimal composition. LiFePO4 (LFP) demonstrator half-cells were assembled with these hybrid solid state electrolyte membranes and displayed a highly reversible capacity for over 100 cycles. Elaborate electrochemical characterization reveals the promising nature of this newest member of the hybrid solid electrolyte family. In the current presentation, we will show the expansion of the eutectogel family via two pathways. First, new deep eutectic electrolytes with higher thermal stability have been designed and confined within a silica matrix. The compositions have been optimized and fully (electro-)chemically characterized for their potential in electrochemical cells. Another route is replacing the silica framework with a polymeric cage. This route allows the further simplification of the synthesis while fully harnessing the potential of the confined deep eutectic electrolyte. Both routes are evaluated for their potential to formulate the design principles for the development of novel eutectogels. Figures Figure 1: (Left) Synthesis route for the eutectogels, optical photograph of a membrane (12 mm diameter) with schematic representation of the nanostructure. (Right) Arrhenius plots of the ionic conductivities for several compositions. Acknowledgements B. Joos is a PhD fellow of the Research Foundation – Flanders (FWO Vlaanderen). This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg (project number EFRO936). The authors would like to thank other group members for their assistance.

Redox Reaction of 2,2,6,6-Tetramethylpiperidine-1-Oxyl (TEMPO) in Lithium Bis(trifluoromethylsulfonyl)Amide-Tetraglyme Solvate Ionic Liquid

Electrode reactions of the redox couples dissolved in liquid electrolytes are able to be utilized for energy storage devices. Vanadium redox flow battery is one of the typical large-scaled energy storage devices using aqueous solutions for both anolye and catholyte.[1] The cell voltages of such aqueous redox flow batteries are often limited by the electrochemical potential window of water. In order to enlarge the cell voltage and increase energy density, it is necessary to use aprotic electrolytes having wider electrochemical potential windows. Typical aprotic electrolytes used for non-aqueous batteries like lithium-ion batteries are composed of organic solvents, which are volatile and flammable. However, such organic electrolytes are unfavorable especially for the large-scaled batteries requiring large amount of electrolytes because of safety in case of accident. Therefore, it is necessary to select less flammable electrolytes for non-aqueous redox flow batteries. The equimolar mixture of lithium bis(trifluoromethylsulfonly)amide (LiTFSA) and tetraglyme (G4) has been known to form the solvate ionic liquid, which is composed of a lithium-G4 complex, [Li(G4)]+, and TFSA–, and exhibits such properties as less volatility, less flammability, and wide electrochemical potential window, similar to those of ionic liquids.[2,3] The high concentration of lithium species in the solvate ionic liquid is also advantageous to the batteries using lithium ion as a charge carrier. Since the cathodic limit of the solvate ionic liquid is determined by deposition and dissolution of lithium, it is possible to construct the batteries combining a lithium anode with the redox reactions dissolved in the solvate ionic liquid using a lithium-ion conductive solid-state electrolyte as a separator between the anolyte and catholyte. We have already proposed the battery using the redox reaction of tris(2,2'-bipyridine)iron(III/II) complexes in the solvate ionic liquid with the cell voltage of about 4 V.[4] In the present study, the redox reaction of a stable free radical, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), was investigated in the solvate ionic liquid, [Li(G4)]TFSA, for application to the redox flow battery. Both TEMPO and its oxidized form, TEMPO+, were found to be soluble in the solvate ionic liquid at ambient temperature. The redox reaction of TEMPO+/TEMPO was observed in the cyclic voltammetry of a glassy carbon electrode in [Li(G4)]TFSA containing TEMPO. The diffusion of TEMPO was found to be faster than that of TEMPO+, probably due to coulombic interaction of TEMPO+ with the ions composing the solvate ionic liquid. The standard rate constant was determined by electrochemical impedance spectroscopy. The temperature dependence of the standard rate constant suggested the redox reaction of TEMPO+/TEMPO can be regarded as an outer-sphere electron transfer reaction with a small reorganization energy. The redox battery was constructed using a lithium anode and the catholyte of the solvate ionic liquid containing TEMPO with a thin lithium-ion conductive solid-state electrolyte membrane. The redox battery could be operated successfully with the average discharge voltage of 3.4 V.

Electrochemical Energy Storage with an Aqueous Quinone–Air Chemistry

Organic electrode materials such as quinones are drawing rising attention as promising redox-active materials for the development of rechargeable batteries. In aqueous solutions, the redox potential of quinones is dependent on the alkalinity and acidity of the medium. Under an alkaline condition, the oxidation potential of hydroquinone (existing as diphenolate) is ca. 0.8 V lower than that under an acidic condition. On the other hand, under an acidic condition, the reduction potential of oxygen is ca. 0.8 V higher than that under an alkaline condition. By taking these advantages, a Quinone-air cell with a rational voltage is strategically demonstrated with an alkaline anode electrolyte and an acidic cathode electrolyte, which are physically separated by a Na+-ion conductive solid-state electrolyte membrane. The Na+-ions shuttling through the solid-state membrane act as ionic mediators/messengers to sustain and link the redox reactions at the two electrodes.

(Invited) Reactions or No Reaction: Lithium Deposition on the Surface of Solid State Electrolyte

Li metal anode has regained intensive interest in recent years in order to develop high energy next-generation battery technologies. Unfortunately, Li metal suffers from poor cycling stability and low efficiency as well as the formation of dangerous Li dendrites raising safety concerns. The employment of solid state electrolyte (SSE) to prevent Li dendrite growth provides a promising approach to address the dendrite issue. However, recent studies indicate that Li dendrites easily form at elevated current densities, while the fundamental mechanisms of forming Li dendrites within SSE is still unknown. This calls for further investigation to understand, and control the detrimental observation. The origin and evolution of Li dendrite growth through SSE will be discussed in this talk by using two different SSE membranes, garnet and phosphate-type, as the separators. During cycling, Li is repeatedly deposited on SSE. Although a good SSE should not react with the deposited Li, the reactions between Li deposits and SSE generate a self-terminating interface, which stops the fast propagation of dendritic Li through the SSE membrane. New insights are provided on the further modification and/or incorporation of interfacial layers between SSE and Li metal to enable future solid state batteries.

Developing lithiated polyvinyl formal based single-ion conductor membrane with a significantly improved ionic conductivity as solid-state electrolyte for batteries

A novel lithiated polyvinyl formal single-ion conductor (Li-PVFM) membrane has been proposed and prepared as polymer electrolyte for Li-ion batteries with excellent mechanical strength of 11–34 MPa and good thermal stability, but the series faces the common issue of solid-state electrolyte - a low ionic conductivity about 10−6 S cm−1 at room temperature. Herein, by purifying the polymer matrix to avoid the negative effect of the impurities on Li+ diffusion, and linking more Li+ from lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) on the matrix to improve the carrier concentration, the as obtained solid-state electrolyte membrane exhibits a significantly improved ambient ionic conductivity in two orders of magnitude to 10−4 S cm−1. The results confirm that the polymer matrix is obtained without any residual oxalate and carbonate, resulting in the increasing ionic conductivity of electrolyte membrane from 10−6 to 10−5 S cm−1. Furthermore, the conductor membrane with modulating the lithium content to 0.80 mol L−1 has a high lithium-ion transference number of 0.81, wide electrochemical stability window of > 5 V (vs. Li+ /Li) and excellent tensile strength of 44.8 MPa. The solid electrolyte batteries using LiFePO4 as cathode material exhibit a reversible capacity of 130 mAh g−1 and a good cycling stability.

Flexible, Solid-State, Ion-Conducting Membrane with 3D Garnet Nanofiber Networks for Lithium Batteries

Beyond state-of-the-art lithium-ion battery (LIB) technology with metallic lithium anodes to replace conventional ion intercalation anode materials is highly desirable because of lithium’s highest specific capacity (3,860 mA/g) and lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode). In this work, we report for the first time, to our knowledge, a 3D lithium-ion–conducting ceramic network based on garnet-type Li6.4La3Zr2Al0.2O12 (LLZO) lithium-ion conductor to provide continuous Li+ transfer channels in a polyethylene oxide (PEO)-based composite. This composite structure further provides structural reinforcement to enhance the mechanical properties of the polymer matrix. The flexible solid-state electrolyte composite membrane exhibited an ionic conductivity of 2.5 × 10−4 S/cm at room temperature. The membrane can effectively block dendrites in a symmetric Li | electrolyte | Li cell during repeated lithium stripping/plating at room temperature, with a current density of 0.2 mA/cm2 for around 500 h and a current density of 0.5 mA/cm2 for over 300 h. The presentation will focus on our recent development of 3D garnet nano structured solid-state electrolyte membrane for Li metal batteries. Figure 1

Enhancement of Li Ion Conductivity by Electrospun Polymer Fibers and Direct Fabrication of Solvent-Free Separator Membranes for Li Ion Batteries

Poly(ethylene oxide) (PEO)-based polymer fibers, containing different amounts of the conductive salt LiBF4 and the plasticizer succinonitrile, were prepared by an electrospinning process. This process resulted in fiber membranes of several square centimeters area and an overall thickness of ∼100 μm. All membranes are characterized by scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, impedance spectroscopy, cyclic voltammetry (CV), and solid-state NMR spectroscopy, to evaluate the influence of the preparation process and the composition on the conductivity of the materials. Impedance spectroscopy was used to measure the conductivities and activation barriers for the different membranes. The highest conductivity of 2 × 10-4 S/cm at room temperature and 9 × 10-4 S/cm at 328 K is reached for a PEO/SN/LiBF4 (36:8:1) membrane, featuring an activation energy of 31 kJ/mol. Li mobilities, as deduced from the evaluation of the temperature dependence of the 7Li NMR line width and the overall electrochemical performance, are found to be distinctively superior to nonspun samples, synthesized via conventional solution casting. The same trend was found for the conductivities. NMR spectroscopy clearly substantiated that the mobility of the PEO segments drastically increases with the addition of succinonitrile pushing the conductivity to reasonable high values. In CV experiments the reversible Li transport through the dry membrane was evaluated and proved. This study shows that electrospinning provides a direct synthesis of solvent-free solid-state electrolyte membranes, ready to use in electrochemical applications.

The Photovoltaic Performances of PVdF-HFP Electrospun Membranes Employed Quasi-Solid-State Dye Sensitized Solar Cells.

The PVdF-HFP nanofiber membranes with different molecular weight were prepared by electrospinning technique and were investigated as solid state electrolyte membranes in quasi solid state dye sensitized solar cells (QS-DSSC). The homogeneously distributed and fully interconnected nanofibers were obtained for all of the prepared PVdF-HFP electrospun membranes and the average fiber diameters of fabricated membranes were dependent upon the molecular weight of polymer. The thermal stability of electrospun PVdF-HFP membrane was decreased with a decrement of molecular weight, specifying the high heat transfer area of small diameter nanofibers. The QS-DSSC fabricated with the lower molecular weight PVdF-HFP electrospun nanofiber membrane exhibited the power conversion efficiency of 1 = 5.38%, which is superior over the high molecular weight membranes and is comparable with the liquid electrolyte. Furthermore, the electrospun PVdF-HFP membrane exhibited long-term durability over the liquid electrolyte, owing to the higher adsorption and retention efficiencies of liquid electrolyte in its highly porous and interconnected nanofibers. Thus the proposed electrospun PVdF-HFP membrane effectively tackled the volatilization and leakage of liquid electrolyte and provided good photoconversion efficiency associated with an excellent stability, which constructs the prepared electrospun membranes as credible solid state candidates for the application of QS-DSSCs.

Cathodes for Solid-State Lithium–Oxygen Cells: Roles of Nasicon Glass-Ceramics

The roles of lithium aluminum germanium phosphate (LAGP) glass-ceramic (GC) in cathodes of totally solid-state lithium–oxygen electrochemical cells are delineated by conducting discharge experiments as a function of cathode chemistry. It is proposed that LAGP possesses an inherent characteristic to adsorb oxygen molecules due to its open structure. The adsorption is followed by reduction of oxygen to superoxide and peroxide molecules. Subsequently, these molecules react with lithium ions to form respective discharge products. In addition to being an important constituent of the cathode, the LAGP also serves as a solid-state electrolyte membrane due to its superionic lithium-ion conductivity. The dual functions of the LAGP GCs make it a feasible material to process an integrated membrane–cathode element of a cell, although this is not demonstrated in this paper.

Laser printing of nanocomposite solid-state electrolyte membranes for Li micro-batteries

The electrochemical and mechanical properties of nanocomposite solid-state electrolyte membranes deposited using a laser direct-write technique from a suspended solution comprised of an ionic liquid (1,2-dimethyl-3- n-butylimidazolium-bis-trifluoromethanesulfonylimide)–polymer (poly(vinylidene fluoride-co-hexafluoropropylene)) matrix with dispersed nano-particles (TiO 2) are reported and discussed. These laser printed nanocomposite solid-state membranes are shown to exhibit the proper electrochemical behavior for ionic liquids while maintaining the strength and flexibility of the polymer matrix. This combination of physical properties and deposition technique makes these deposited nanocomposite membranes ideally suited for use as an electrolyte/separator in Li micro-batteries. Sample Li micro-batteries using these laser printed nanocomposite membranes have been fabricated and their charge/discharge behavior tested, demonstrating the feasibility of using these nanocomposite membranes in Li micro-battery applications.

Solid state electrolyte membranes for direct methanol fuel cells

Solid state electrolyte membranes for direct methanol fuel cells were prepared from proton conductors and a polymer binder. The most promising proton conductor was tin oxide-containing mordenite, the conductivity of which was retained in the membranes. The diffusion of methanol across the membranes and the solvent uptake were lower than for commercial electrolyte membranes.