Inorganic Organic Polymer Electrolytes Research Articles

Development of a Polymer-Based Silicon-NMC Solid-State Cell

Solid-state batteries are seen as the next generation of battery technology with the promise of high energy density and improved safety as compared to conventional lithium-ion batteries. To achieve these goals, high-capacity negative electrodes, e.g., silicon or lithium, need to be combined with high capacity and high voltage positive electrodes, e.g., Ni-rich NMC. This combination of active materials provides a number of significant challenges for the solid-state electrolyte. If silicon is used as the anode active material, significant volume changes during lithiation/delithiation occur. These volume changes lead to a variety of problems including irreversible loss of lithium and eventual disintegration of the electrodes, resulting in capacity fade. Therefore, the electrolyte must be sufficiently elastic to buffer these changes. If Ni-rich NMC is used as a cathode active material, then the electrolyte must be stable at voltages up to at least 4.2 V. There are currently few, if any, electrolyte solutions that can address these challenges simultaneously.In the ASTRABAT project, a silicon-NMC solid-state cell has been developed based on two tailored polymer electrolytes, which allows the specific challenges of each cell compartment to be addressed separately. A vinylidene fluoride copolymer-based electrolyte has been developed for use as a catholyte and a hybrid inorganic-organic polymer electrolyte as the anolyte. This work will report a characterization of both electrolytes, along with their electrochemical performance in solid-state half-cells and full-cells.

Elucidation of the Interplay between the Features of the Precursor and the Physicochemical Properties of “Core-Shell” Hierarchical Carbon Nitride Electrocatalysts for the Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is a major bottleneck in the operation of proton-exchange membrane fuel cells (PEMFCs) since it introduces large overpotentials (no less than 250-300 mV), which degrade significantly the energy conversion efficiency of the device. In addition, the electrocatalysts (ECs) yielding the lowest ORR overpotentials in the acidic environment found at the PEMFC cathode are based on Pt, a very scarce critical raw material (CRM). Pt raises concerns as it might trigger serious supply bottlenecks in the event of a practical widespread implementation of PEMFCs in the framework of today’s energy transition. Hence, the development of high-performing and durable ECs for the ORR is a major stepping stone towards the large-scale rollout of PEMFCs.In our research group a new breakthrough approach has been devised for the synthesis of ORR ECs, that is completely different form the preparation routes that are commonly adopted in the state of the art [1, 2]. Briefly, the approach consists in the pyrolysis and subsequent treatment of a precursor obtained by coupling suitable carbon species/sacrificial supports with a zeolitic inorganic-organic polymer electrolyte (Z-IOPE). The latter comprises anionic complexes including the Pt “catalyst” and other “co-catalysts”, which are bridged by organic binders [1,2].On one hand, the proposed approach has already shown its potential to yield ECs exhibiting a performance and durability improved with respect to Pt/C benchmark ECs. On the other hand, the proposed approach is extremely flexible, especially with respect to the synthesis of the initial EC precursor. In principle, it is possible to modulate a number of crucial features of such EC precursor, with a particular reference to: (i) the chemical composition (e.g., in terms of Pt, other “co-catalysts” and N; the latter plays a crucial role to stabilize the active sites into “coordination nests” on the EC surface, raising durability); and (ii) the morphology, that can be “templated” on suitable species (e.g., carbon species, sacrificial supports). The very flexibility of the proposed synthetic process needs to be leveraged appropriately to maximize the performance of the final ORR ECs, at the same time minimizing the efforts wasted on approaches with a low development potential.Herein it is elucidated how the modulation in the parameters involved in the synthesis of the EC precursor (e.g., the binder and the approaches to couple the Z-IOPE with the support) impact the physicochemical and electrochemical properties of the final ECs, with a particular reference to the chemical composition, morphology and distribution of the ORR active sites. An extensive characterization of the final ECs is carried out. Inductively-coupled plasma atomic emission spectroscopy (ICP-AES) and microanalysis are adopted to determine the bulk chemical composition. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is used to elucidate the surface chemical composition and the chemical states of the surface elements. Ultra-high resolution scanning electron microscopy (UHR-SEM) and transmission electron microscopy (TEM) allow for the elucidation of EC morphology. The porosimetric features are probed by automatic gas adsorption instrumentations. Wide-angle X-ray diffraction (WAXD) is crucial to resolve the crystal structure. Cyclic voltammetry with the rotating ring-disk electrode method (CV-TF-RRDE) is used to clarify the “ex-situ” electrochemical performance and ORR reaction mechanism. Finally, the most promising ECs are used in the fabrication of single PEMFCs, that are tested as a function of the operating conditions.It is revealed that, in comparison with the Pt/C benchamark, some ECs are characterized by a much higher intrinsic kinetic performance due to the electronic and bifunctional effects bestowed by the carbon nitride support and the «co-catalysts». Finally, the binder has a marked effect on the stoichiometry, size, and distribution of the PtMx aggregates bearing the active sites.

(Invited) Solid State Hybrid Inorganic Organic Polymer Electrolytes for Advanced Sodium Secondary Batteries

The large-scale rollout of electric vehicles, smart grids and portable electronics is expected to require an amount of energy storage devices that the Li-ion technology alone will not be able to satisfy. In this concern, a quest for novel electrochemical energy storage technologies has started [1]. Sodium secondary batteries appear to be a good choice due to: (i) the high availability of raw materials; (ii) the low cost of sodium; (iii) the low sodium standard reduction potential; and (iv) the similarity between the chemistries of sodium and lithium, which facilitates the transition between the two technologies. Up to date, the best-performing electrolytes for the reversible deposition of sodium are based on organic solvents, which suffer from safety concerns and a poor stability towards sodium metal. Thus, research activities in this field are devoted to the development of safe and stable solid state electrolytes able to efficiently transport Na+ ions.Inspired by the pioneering work done by Di Noto and co-workers [2-4], herein we present a family of hybrid inorganic-organic polymer electrolytes (HIOPEs) for advanced solid state sodium secondary batteries. The initial HIOPE is obtained by means of a reaction between zirconium ethoxide and polyethylene glycol (PEG400). The resulting material is doped with sodium perchlorate as source of Na+ ions. In this system a 3D network is obtained, where inorganic zirconium metal nodes are interconnected by means of organic PEO chains. The latter ensure flexibility to the overall structure. Na+ ions are coordinated by and exchanged between the oxygen atoms of the ethereal functionalities of PEO chains. In addition, to guarantee a good structural stability, positively charged Zr nodes partially coordinate perchlorate anions, thus raising the sodium transference number. After doping with the poly(ethylene glycol) dimethyl ether (PEGDME250) plasticizer, a room temperature conductivity higher than 10-4 S cm-1 is demonstrated. An advanced study of the thermal and structural properties of the proposed materials is presented, with a particular focus on the interactions established between the different chemical species and complexes composing the HIOPEs. The conduction mechanism is elucidated starting from the results obtained in a wide range of temperatures from broadband electrical spectroscopy studies. Taking all together, this study offers insights on the application of non-traditional solid state electrochemical functional components as replacements for conventional solvents in the emerging field of sodium secondary batteries. Acknowledgments The project “Interplay between structure, properties, relaxations and conductivity mechanism in new electrolytes for secondary Magnesium batteries” (Grant Agreement W911NF-21-1-0347-(78622-CH-INT)) of the U.S. Army Research Office. The project “ACHILLES” (prot. BIRD219831) of the University of Padua. The project “VIDICAT” (Grant Agreement 829145) of the FET-Open call of Horizion 2020. The project TRUST (protocol 2017MCEEY4) of the Italian MIUR funded in the framework of “PRIN 2017” call.

(Keynote) Interplay between Physicochemical Properties of Precursors and “Core-Shell” Hierarchical Carbon Nitride Electrocatalysts for the Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is a major bottleneck in the operation of proton-exchange membrane fuel cells (PEMFCs) since it introduces large overpotentials (no less than 250-300 mV), which degrade significantly the energy conversion efficiency of the device. In addition, the electrocatalysts (ECs) yielding the lowest ORR overpotentials in the acidic environment found at the PEMFC cathode are based on Pt, a very scarce critical raw material (CRM). Pt raises concerns as it might trigger serious supply bottlenecks in the event of a practical widespread implementation of PEMFCs in the framework of today’s energy transition. Hence, the development of high-performing and durable ECs for the ORR is a major stepping stone towards the large-scale rollout of PEMFCs.In our research group a new breakthrough approach has been devised for the synthesis of ORR ECs, that is completely different form the preparation routes that are commonly adopted in the state of the art [1, 2]. Briefly, the approach consists in the pyrolysis and subsequent treatment of a precursor obtained by coupling suitable carbon species/sacrificial supports with a zeolitic inorganic-organic polymer electrolyte (Z-IOPE). The latter comprises anionic complexes including the Pt “catalyst” and other “co-catalysts”, which are bridged by organic binders [1,2].On one hand, the proposed approach has already shown its potential to yield ECs exhibiting a performance and durability improved with respect to Pt/C benchmark ECs. On the other hand, the proposed approach is extremely flexible, especially with respect to the synthesis of the initial EC precursor. In principle, it is possible to modulate a number of crucial features of such EC precursor, with a particular reference to: (i) the chemical composition (e.g., in terms of Pt, other “co-catalysts” and N; the latter plays a crucial role to stabilize the active sites into “coordination nests” on the EC surface, raising durability); and (ii) the morphology, that can be “templated” on suitable species (e.g., carbon species, sacrificial supports). The very flexibility of the proposed synthetic process needs to be leveraged appropriately to maximize the performance of the final ORR ECs, at the same time minimizing the efforts wasted on approaches with a low development potential.Herein it is elucidated how the modulation in the parameters involved in the synthesis of the EC precursor (e.g., the binder and the approaches to couple the Z-IOPE with the support) impact the physicochemical and electrochemical properties of the final ECs, with a particular reference to the chemical composition, morphology and distribution of the ORR active sites. An extensive characterization of the final ECs is carried out. Inductively-coupled plasma atomic emission spectroscopy (ICP-AES) and microanalysis are adopted to determine the bulk chemical composition. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is used to elucidate the surface chemical composition and the chemical states of the surface elements. Ultra-high resolution scanning electron microscopy (UHR-SEM) and transmission electron microscopy (TEM) allow for the elucidation of EC morphology. The porosimetric features are probed by automatic gas adsorption instrumentations. Wide-angle X-ray diffraction (WAXD) is crucial to resolve the crystal structure. Cyclic voltammetry with the rotating ring-disk electrode method (CV-TF-RRDE) is used to clarify the “ex-situ” electrochemical performance and ORR reaction mechanism. Finally, the most promising ECs are used in the fabrication of single PEMFCs, that are tested as a function of the operating conditions.It is revealed that, in comparison with the Pt/C benchamark, some ECs are characterized by a much higher intrinsic kinetic performance due to the electronic and bifunctional effects bestowed by the carbon nitride support and the «co-catalysts». Finally, the binder has a marked effect on the stoichiometry, size, and distribution of the PtMx aggregates bearing the active sites.

A New Glass-Forming Electrolyte Based on Lithium Glycerolate

The detailed study of the interplay between the physicochemical properties and the long-range charge migration mechanism of polymer electrolytes able to carry lithium ions is crucial in the development of next-generation lithium batteries. Glycerol exhibits a number of features (e.g., glass-forming behavior, low glass transition temperature, high flexibility of the backbone, and efficient coordination of lithium ions) that make it an appealing ion-conducting medium and a challenging building block in the preparation of new inorganic–organic polymer electrolytes. This work reports the preparation and the extensive investigation of a family of 11 electrolytes based on lithium glycerolate. The electrolytes have the formula C3H5(OH)3−x(OLi)x, where 0 ≤ x ≤ 1. The elemental composition is evaluated by inductively coupled plasma atomic emission spectroscopy. The structure and interactions are studied by vibrational spectroscopies (FT-IR and micro-Raman). The thermal properties are gauged by modulated differential scanning calorimetry and thermogravimetric analysis. Finally, insights on the long-range charge migration mechanism and glycerol relaxation events are investigated via broadband electrical spectroscopy. Results show that in these electrolytes, glycerolate acts as a large and flexible macro-anion, bestowing to the material single-ion conductivity (1.99 × 10−4 at 30 °C and 1.55 × 10−2 S∙cm−1 at 150 °C for x = 0.250).

Synthesis, studies and fuel cell performance of “core–shell” electrocatalysts for oxygen reduction reaction based on a PtNix carbon nitride “shell” and a pyrolyzed polyketone nanoball “core”

This report describes a new class of “core–shell” electrocatalysts for oxygen reduction reaction (ORR) processes for application in Proton Exchange Membrane Fuel Cells (PEMFCs). The electrocatalysts are obtained by supporting a “shell” consisting of PtNix alloy nanoparticles embedded into a carbon nitride matrix (indicated as PtNix-CN) on a “core” of pyrolyzed polyketone nanoballs, labeled ‘STp’. STps are obtained by the sulfonation and pyrolysis of a precursor consisting of XC-72R carbon nanoparticles wrapped by polyketone (PK) fibers. The STps are extensively characterized in terms of the chemical composition, thermal stability, degree of graphitization and morphology. The “core–shell” ORR electrocatalysts are prepared by the pyrolysis of precursors obtained impregnating the STp “cores” with a zeolitic inorganic–organic polymer electrolyte (Z-IOPE) plastic material. The electrochemical performance of the electrocatalysts in the ORR is tested “in situ” by single fuel cell tests. The interplay between the chemical composition, the degree of graphitization of both PtNix-CN “shell” and STps “cores”, the morphology of the electrocatalysts and the fuel cell performance is elucidated. The most crucial preparation parameters for the optimization of the various features affecting the fuel cell performance of this promising class of ORR electrocatalysts are identified.

Interplay between structural and electrochemical properties of Pt-Rh carbon nitride electrocatalysts for the oxygen reduction reaction

This report describes a new family of bimetal carbon nitride (CN) electrocatalysts for the oxygen reduction reaction (ORR) for application in polymer electrolyte membrane fuel cells (PEMFCs). The materials, which bear active sites based on Pt and Rh, are prepared with a three-step protocol consisting of: (1) the synthesis of a homogeneous zeolitic inorganic–organic polymer electrolyte (Z-IOPE) precursor; (2) the pyrolysis of the precursor at a temperature T f = 400, 500, 600, 700 or 900 °C; (3) the activation, yielding the final product. It is found that T f has a major effect on the structure and the electrochemical properties of these electrocatalysts, as determined from a wide array of independent characterization techniques including: high-resolution thermogravimetry (HR-TGA); Fourier-transform medium infrared (FT-MIR), Fourier-transform far infrared (FT-FIR) and confocal micro-Raman spectroscopies; powder X-ray diffraction (powder XRD); X-ray photoelectron spectroscopy (XPS); and electrochemical investigations carried out with the cyclic voltammetry thin-film rotating disk electrode (CV-TF-RDE) method. All the information is integrated to propose a comprehensive model correlating the effect of T f on the structure of the materials with the corresponding electrochemical performance. The best results in the ORR are obtained with materials prepared at 600 ≤ T f ≤ 700 °C. These systems present the optimal compromise between the size of the metal-rich nanoparticles, the degree of graphitization of the carbon nitride support and the concentration of ligands blocking the active sites. The best Pt-Rh electrocatalysts exhibit an ORR activity very similar to the Pt/C reference. In addition, the peculiar structure of the proposed materials, which are characterized by active sites supported on the carbon nitride bulky materials, results in a better tolerance toward typical contaminants in the ORR process such as chloride anions with respect to the Pt/C reference.

Inorganic–organic polymer electrolytes based on poly(vinyl alcohol) and borane/poly(ethylene glycol) monomethyl ether for Li-ion batteries

In this study, poly(vinyl alcohol) (PVA) was modified with poly(ethylene glycol) monomethyl ether (PEGME) using borane–tetrahydrofuran (BH 3/THF) complex. Molecular weights of both PVA and PEGME were varied prior to reaction. Boron containing comb-branched copolymers were produced and abbreviated as PVA1PEGMEX and PVA2PEGMEX. Then polymer electrolytes were successfully prepared by doping of the host matrix with CF 3SO 3Li at several stoichiomeric ratios with respect to EO to Li. The materials were characterized via nuclear magnetic resonance ( 1H NMR and 11B NMR), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG) and differential scanning calorimeter (DSC). The ionic conductivity of these novel polymer electrolytes were studied by dielectric-impedance spectroscopy. Li-ion conductivity of these polymer electrolytes depends on the length of the side units as well as the doping ratio. Such electrolytes possess satisfactory ambient temperature ionic conductivity (>10 −4 S cm −1). Cyclic voltammetry results illustrated that the electrochemical stability domain extends over 4 V.

Hybrid inorganic–organic proton exchange membranes containing 1 H-1,2,3-triazole moieties

Hybrid inorganic–organic polymer electrolyte membranes (PEM) were synthesized from a combination of 1 H-1,2,3-triazole grafted alkoxy silanes, tetraethoxy silane (TEOS), polyethylene glycol (PEG) and trifluoroacetic acid (TFA) or phosphoric acid. The resulting hybrid inorganic–organic proton exchange membranes were self-supporting and thermally stable up to 180 °C. Evaluation of proton conductivity as a function of temperature indicates that by using sol–gel chemistry, it is possible to achieve mechanically robust membranes having proton conductivity comparable to uncrosslinked, liquid-like 1 H-1,2,3-triazole functionalized polysiloxane homopolymer. Mechanical properties of these hybrid inorganic–organic membranes were investigated using nanoindentation.

A new Pt–Rh carbon nitride electrocatalyst for the oxygen reduction reaction in polymer electrolyte membrane fuel cells: Synthesis, characterization and single-cell performance

In this paper the preparation of a new bimetal electrocatalyst for the oxygen reduction reaction (ORR), which is one of the most important bottlenecks in the operation of polymer electrolyte membrane fuel cells (PEMFCs), is described. This material was synthesized through a pyrolysis process of a zeolitic inorganic–organic polymer electrolyte (Z-IOPE-like) precursor, followed by suitable washing and activation procedures of the product. The electrocatalyst, whose active sites consist of platinum and rhodium, was: (a) extensively characterized from the chemical, structural, morphological and electrochemical points of view and (b) used to prepare a membrane-electrode assembly (MEA) which was tested under operative conditions in a single-cell configuration. It was observed that, with respect to a reference material based on supported platinum, rhodium did not compromise the performance of the electrocatalyst in the ORR. This behaviour was interpreted in the framework of a general model concerning the enhancement of ORR performance in bimetal systems supported on carbon nitrides. Finally, the material shows a slightly better tolerance toward a few common contaminants for the ORR such as methanol and chloride anions, typical of direct methanol fuel cells (DMFCs) and vehicular applications, respectively.

New hybrid inorganic–organic polymer electrolytes based on Zr(O(CH 2) 3CH 3) 4, glycerol and EMIm-TFSI ionic liquid

This report presents detailed studies on the elemental analysis, vibrational spectroscopy, thermal stability and electrical spectroscopy of two new hybrid inorganic–organic polymers which have been synthesised by a sol–gel method using glycerol and zirconium(IV)butoxide as precursors. These materials have been doped by means of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) ionic liquid (IL), which is insoluble in water. The elemental composition of the obtained polymers [Zr(C 6O 5H 11)] ( 1) and [Zr(C 11O 4H 31)] ( 2) has been determined by CHN analysis and by ICP-AES measurements. FT-IR and FT-Raman spectroscopy investigations have been performed to study the molecular structure of the polymers and the interactions of EMIm-TFSI with the host networks. Differential scanning calorimetry measurements show the presence of at least one glass transition temperature ( T g) in both 1 and 2 materials. The broadband dielectric spectroscopic measurements have been carried out between 10 −2 Hz to 10 MHz from −100 °C to 100 °C with a 5 °C step. The conductivities of the polymers 1 and 2 have been found to be in the order of 10 −8 to 10 −11 S cm −1 at 25 °C, so they can be defined as dielectric materials. After doping 2 with EMIm-TFSI, the conductivity at 25 °C of the obtained complex [Zr(C 11O 4H 31)] 15/(EMIm-TFSI) ( 2′) increased three orders of magnitude resulting ca. 10 −5 S cm −1. The permittivity spectra revealed two relaxation bands which were attributed to the α relaxation modes of the polymer networks.

Effect of subcritical CO 2 on ionic conductivity of {Al[O(CH 2CH 2O) 8.7] ρ/(LiClO 4) z} n hybrid inorganic–organic networks

The aim of this work is to study the effect of CO 2 under pressure on hybrid inorganic–organic polymer electrolytes, by using broad band dielectric spectroscopy (BDS) in the frequency interval 40 Hz–10 MHz and in the temperature range of −80 to 120 °C. Eleven inorganic–organic hybrid materials of the ORMOCERs type, with general formula {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n were treated by applying CO 2 at 293 K and 5 MPa. The results demonstrated that the CO 2 treatment generally depressed the conductivity of about one order of magnitude. The decreased conductivity in treated complexes is explained in terms of a smaller anion-trapping ability of the Al centers. Residual CO 2 molecules are likely to inhibit the interaction of the perchlorate anions with Al centers within the structure. Segmental motion of the polymer chains plays a crucial role in the conductivity of investigated samples, while the ion-hopping phenomenon is the most important charge transfer mechanism both in the pristine and CO 2 treated materials. Equivalent conductivity studies have elucidated the different ionic species present at various salt concentrations and gave insight about the role of CO 2 in modifying the transport properties of the samples.

Effect of subcritical CO 2 on the structural and electrical properties of ORMOCERS-APE systems based on Zr and Al

Two series of hybrid inorganic–organic polymer electrolytes of the organically modified ceramics as polymer electrolytes (ORMOCERS-APE) type with formulas {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n (1.85 ≤ ρ ≤ 2.24, 0 ≤ z ≤ 1.06) and {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n (1.80 ≤ ρ ≤ 1.99, 0 ≤ z ≤ 0.90) were treated with CO 2 in subcritical conditions (293 K and 5 MPa). The effect of CO 2 on the samples was investigated by using ESEM, thermal analysis (TG and DSC) and broad band dielectric spectroscopy (BDS). Both complexes {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n and {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n after CO 2 treatment exhibited a change in the segmental relaxation with respect to the untreated samples. This phenomenon has been interpreted in terms of higher portion of free volume in the samples. The CO 2 treatment primarily lowered the conductivity of {Al[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n complexes of about one order of magnitude, as opposed to {Zr[O(CH 2CH 2O) 8.7] ρ /(LiClO 4) z } n complexes, where an increment of two orders of magnitude was observed. In both cases the conductivity of the treated and untreated materials versus the reciprocal absolute temperature presents the typical Vogel–Tamman–Fulcher (VTF) behavior. The different effects on the conductivities of the treated complexes are explained in terms of the modified anion-trapping ability of Al centers and in terms of the interactions of subcritical CO 2 with the host polymer and the salt. Insight about the conductivity mechanisms were provided by the study of the VTF parameters and the relaxation times determined from the Debye peaks of the imaginary resistivity, the imaginary permittivity and the correlated motion analysis.

A Lithium Z-IOPE Ionomer Based on PEG600, ( CH3 ) 2SnCl2, and Li3Fe ( CN ) 6

In this report, the preparation of a new zeolitic inorganic-organic polymer electrolyte (Z-IOPE) ionomer material by using , , and poly(ethylene glycol)600 as precursors is described. Scanning electron microscopy measurements, vibrational spectroscopy studies (far infrared, medium infrared, Raman laser), UV-visible investigations and microanalytical data gave detailed insight about the morphological and structural characteristics of this electrolytic complex and about the ion-ion/ion-polymer interactions in the system. Thermogravimetric and differential scanning calorimetry studies indicated that: (i) the material is stable up to ; (ii) the is equal to ; (iii) a crystallization process occurs at 20.9°C. and nuclear magnetic resonance measurements of the linewidth, spin-lattice relaxation, and pulsed field gradient diffusion were carried out suggesting the correlation of the lithium dynamics with polymer mobility. The conductivity mechanism in bulk material was investigated by electrical spectroscopy in the 10 mHz to 1 GHz range, between and 80°C. The results were interpreted in terms of the relaxation events detected in the real and imaginary components of dielectric and conductivity spectra. The overall investigation led to the conclusion that the material conducts ionically, with a conductivity of at 25.1°C with unity lithium transport number.

UV-cured hybrid inorganic-organic polymer electrolyte based on organically modified polysiloxane

UV-cured hybrid inorganic-organic polymer electrolyte based on organically modified polysiloxane

UV-cured hybrid inorganic-organic polymer electrolyte based on organically modified polysiloxane

Hybrid inorganic-organic polymer electrolyte based on the monomer of organically modified polysiloxane was prepared by UV radiation curing in the presence of liquid electrolyte. The organically modified polysiloxane monomer with acrylate groups at the terminal position was synthesized by hydrolytic condensation of tetramethoxysilane (TMOS) and followed by demethanolation reaction using 2-hydroxyethyl acrylate (2-HEA). The rational formula of the monomer was SiO1.1436(OH)0.01606(OCH3)1.3394(OCH2CH2OCOCH= CH2)0.3574 which was determined by proton nuclear magnetic resonance (1H-NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and silica analysis. The monomer was polyfunctional with a number average molecular weight of 1185 and a weight average molecular weight of 2292 determined by GPC analysis. The electrochemical properties of the hybrid inorganic-organic polymer electrolyte were determined by ac impedance spectroscopy and cyclic voltammetry. Ionic conductivity was greatly enhanced with increasing amounts of liquid electrolyte. When the polymer electrolyte contained 80 wt% liquid electrolytes, the conductivities were around 3.3 × 10−3 S cm−1 at 21°C and 8.0 × 10−4 S cm−1 even at −23°C. Interface resistance increased initially and reached a steady value after 2 days. Oxidation stability was up to 5.0 V against the lithium reference electrode and electrochemical plating/stripping of lithium on the stainless steel electrode was reversible.

A novel inorganic–organic polymer electrolyte with a high conductivity: insertion of poly(ethylene) oxide into LiV3O8in one step

A novel nanocomposite, PEO–LiV3O8, was synthesized by the intercalation of poly(ethylene) oxide (PEO) into the interlayers of LiV3O8 in one step. It was found that the two different components were combined on the nano-scale; the insertion of polymer was topotactic and did not cause structural changes in the layered host. The single-step weight loss (11.8 wt%) with TG/DSC measurement and other characterization results from XRD, FTIR, Raman, SEM, and TEM revealed that the putative molecular structure of PEO within the layers was similar to the zig-zag Type-I conformation of PEO–HgCl2. The inserted PEO chains decreased the interaction of the negative V3O8− layers with Li+ ions. Because a few interlayered PEO chains extended from the lamellae and connected further with each other, the adjacent PEO–LiV3O8 crystals were aggregated, thus providing a novel and suitable two-dimensional channel for Li+ ions to quickly transfer between the nancomposite grains. This particular hybrid structure of PEO–LiV3O8 resulted in an improvement of the electrochemical properties. The room temperature conductivity of PEO–LiV3O8 (2.99 × 10−4 S cm−1) was superior to that of the conventional SPEs (LiClO4–PEO, 1.1 × 10−7 S cm−1) and the host material LiV3O8 (8.68 × 10−5 S cm−1). Similar observations were also noted in other experimental parameters, such as the activation energy, diffusion coefficient of Li+ ions, and conductivity calculated by fitting EIS data.

Inorganic-Organic Polymer Electrolytes Based on PEG400 and Al [ OCH ( CH 3 ) 2 ] 3: II. Morphology, Thermal Stability, and Conductivity Mechanism

This report presents detailed studies on the morphology, thermal stability, and electrical spectroscopy of 11 aluminum-containing hybrid inorganic-organic polymer electrolytes with the general formula where and Scanning electron microscopy showed a solid-plastic appearance and a smooth texture on the surface of the bulk materials. Thermogravimetric investigations indicated that the hybrid polymer electrolytes are thermally stable up to ∼260°C. Furthermore, a detailed study of the mechanism of ion conduction in these systems was carried out by impedance spectroscopy in the 20 Hz to 1 MHz range and at temperatures varying from 18 to 80°C. It was demonstrated that the materials conduct ionically by a charge-transfer mechanism mainly regulated by segmental motion and fast ion-hopping processes between equivalent coordination sites distributed along polyether chains. The “anion trapping” ability of the aluminum atoms toward perchlorate contributes greatly to the conductivity performance of the networks. Finally, the best conductivity observed in these materials is at © 2004 The Electrochemical Society. All rights reserved.

The first lithium zeolitic inorganic–organic polymer electrolyte based on PEG600, Li 2PdCl 4 and Li 3Fe(CN) 6: part II, thermal stability, morphology and ion conduction mechanism

This paper reports studies on the morphology, thermal stability, NMR and electrical spectroscopy of the first lithium zeolitic inorganic–organic polymer electrolyte (Z-IOPE) with the formula [Fe x Pd y (CN) z Cl v (C 2 n H 4 n+2 O n+1 )Li l ]. Both 1H and 7Li NMR linewidth, spin-lattice relaxation, and pulsed field gradient diffusion measurements were conducted, and the results suggest that the lithium ion transport is correlated with polymer mobility, as in the case of “conventional” polymer electrolytes. A detailed study of the mechanism of ion conduction in bulk material has been carried out also by electrical spectroscopy measurements in the 10 mHz–1 GHz range. The electrical spectra for frequencies higher than 15 kHz evidenced the presence of relaxation events associated to local ion motion dynamics and long range diffusion. These two phenomena were interpreted in terms of (a) ion hopping processes; (b) site relaxations; and (c) host medium reorganization processes. Taken together, these studies demonstrated that at temperatures higher than 35 °C, the Z-IOPE conducts ionically by charge transfer mechanisms mainly regulated by ion hopping between equivalent polyether coordination sites followed by correlated host medium reorganizations. Finally, a conductivity of 5.3×10 −5 S cm −1 at 35 °C classifies this hybrid inorganic–organic network as a good lithium ion conductor.

The first lithium zeolitic inorganic–organic polymer electrolyte based on PEG600, Li 2PdCl 4 and Li 3Fe(CN) 6: part I, synthesis and vibrational studies

The synthesis of Li 2PdCl 4 and Li 3Fe(CN) 6 precursors, and the preparation of the first lithium Z-IOPE material obtained by reacting these precursors with poly(ethylene glycol)600 (PEG600) is reported. This new material has been obtained through a sol⇒gel and gel⇒plastic transition. FIR and MIR spectroscopy studies, Raman laser and UV–vis investigations and detailed compositional data allowed us to propose a structural hypothesis and to detect the interactions between ions and the coordinating segments of the host network. It has been concluded that: (1) this compound is a mixed inorganic–organic network in which clusters formed by palladium and iron complexes are bonded together by PEG bridges; (2) the conformation of polyether chains in the bulk material is of the TGT (T= trans, G= gauche) type. The conductivity of the proposed [Fe xPd y(CN) zCl v(C 2nH 4n+2O n+1)Li l] is ≈5.3×10 −5 S cm −1 at 35.1 °C.