Flexible and high ion conducting solid polymer electrolytes prepared via ring-opening polymerization

Abstract

The chemical cross-linking of epoxy resin has been known as an imperative way to improve the mechanical strength and thermal stability of solid polymer electrolytes (SPEs). Herein, we prepare flexible epoxy-based SPEs with high ion conductivity for electrochemical devices via ring-opening polymerization. A diglycidyl ether of bisphenol-A (DGEBA) epoxy resin was selected as the mechanical supporting SPE matrix. The high flexibility of SPEs can be obtained by adding poly(ethylene glycol) diglycidyl ether (PEGDE) plasticizer to the epoxy resin. Furthermore, the incorporation of electrolyte mixture of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salts and 1-butyl-3 methylimidazolium bis(trifluorosulfonyl)imide (BMIM-TFSI) ionic liquids allows for boosting ionic conductivity of the epoxy-based SPEs. Consequently, the high room temperature ionic conductivity ～2.4?×?10^?3 S/cm was achieved in the SPE containing 30?wt% of the epoxy and 70?wt% of the electrolyte mixture.     

The role of inorganic nanoparticle on ion conduction of epoxy-based solid polymer electrolytes for lithium-ion batteries

Abstract

Recently, extensive efforts have focused on the development of solid polymer electrolytes (SPEs) requiring high mechanical performance without sacrificing ion conductivity. To develop such a SPE, we incorporate robust silica mesoporous particles (SMP) into the epoxy-based SPEs, and increasing the SMP content raises the glass transition temperature of the SPEs. This enables to increase the mechanical properties of the SPEs, supported by the microstructural investigation showing a highly compact structure. Ionic conductivities of these SPEs follow Vogel temperature dependence, and increasing the silica nanoparticle content leads to a slight decrease in the conductivity, consistent with the dielectric response investigation.     

Electrochemical characterizations and the effect of glycerol in biopolymer electrolytes based on methylcellulose-potato starch blend

ABSTRACT

Polymer electrolytes have been prepared by blending methylcellulose (MC)-potato starch, doped with lithium perchlorate (LiClO₄) and plasticized with glycerol. The blend of 60 wt% MC-40 wt% starch was found to be the most suitable ratio to serve as polymer host. Fourier transform infrared (FTIR) spectroscopy analysis proved the interaction among the components. X-ray diffraction (XRD) analysis indicated that the conductivity enhancement is due to the increase in amorphous content. The highest ionic conductivity obtained at room temperature was (4.25 ± 0.82) × 10^?4 S cm^?1 for MC-starch-LiClO₄-20 wt% glycerol. The highest conducting samples in both systems were found to obey Arrhenius rule. Dielectric study further strengthens the conductivity result.     

Addition effects of bismuth oxide on Samaria-doped ceria based lithium carbonate composite electrolytes for intermediate temperature-solid oxide fuel cells

ABSTRACT

The effect of amounts (3, 5, 10, 20 wt%) of Bi₂O₃ on the sintering characteristics and porosity of Samaria-doped Ceria (SDC) based Lithium carbonate has been evaluated. The density had a maximum as high as 98.5% of theoretical density at 800°C with only 1wt%Li₂CO₃ and 3 wt%Bi₂O₃. The composite electrolytes showed high ion conductivity at evaluated temperatures. Composition and calcination temperature were found to affect the morphology and conductivity of the composite electrolytes greatly. The total conductivity closed to 3 orders of magnitude greater than pure SDC at operating temperature of 900°C and 3.5 orders of magnitude greater than pure SDC at operating temperature of 600°C. Especially, the best sample containing 3 wt% Bi₂O₃ sintered at 800°C for 2 h which had an ionic electrical conductivity of 0.17S cm^?1. According to fuel cell performance, these composite electrolytes are chemically stable, which is an attractive prospect in intermediate temperature solid oxide fuel cell applications.     

Study of ion transport in Li<Subscript>2</Subscript>ZrO<Subscript>3</Subscript> solid electrolytes with different lithium isotope ratios

Lithium ionic conductivity and spin-lattice relaxation rates were measured in Li₂ZrO₃ solid electrolytes with different ⁶Li and ⁷Li ratios. It is found that single-isotope electrolytes undergo a transition to the superionic state in the temperature range of 430–450 K, accompanied by an abrupt increase in conductivity. As a result of introduction of the other type of the isotope, the conductivity jump disappears in this temperature range. The transition to the superionic state is attributed to the redistribution of lithium ions over energetically nonequivalent lattice sites.     

Electrical Conductivity and Thermoelectric Power of Silver Iododichromate Fast Ion Conducting Electrolytes

Fast ion conducting solid electrolytes are becoming increasingly important owing to their application in solid state ionic devices. The present work deals with the silver ion conducting x AgI – (1–x)Ag₂Cr₂O₇ electrolyte system. These electrolytes have been characterised by X-ray diffraction, electrical conductivity, electronic conductivity and thermoelectric power techniques. A high ionic conductivity of the order of 10⁻³ S/cm has been observed for the composition mol% 80 AgI–20 Ag₂Cr₂O₇, at room temperature. The electronic conductivity of this electrolyte is three orders of magnitude lower than the ionic conductivity.     

Structural,morphological, ionic conductivity,and thermal properties of pectin-based polymer electrolytes

New polymer electrolytes (PEs), potentially interesting for solid-state electrochemical devices applications, were synthesized by a solvent casting method using pectin and ionic liquid (IL) N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ([N_{1 1 1 2(OH)}] [NTf₂]. The resulting electrolytes besides being moderately homogenous and thermally stable below 155°C, they also exhibited good mechanical properties. The SPE membranes were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and complex impedance spectroscopy.     

Evaluation and investigation on the effect of ionic liquid onto PMMA-PVC gel polymer blend electrolytes

1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide), BmImTFSI based poly(methyl methacrylate)-poly (vinyl chloride), PMMA-PVC gel polymer electrolytes were prepared by solution casting technique. These ionic liquid-based gel polymer electrolytes exhibit Arrhenius type temperature dependence of ionic conductivity. The highest ionic conductivity of (8.08 ± 0.01) × 10^− 4 Scm⁻¹ was achieved at 80 °C upon addition of 60 wt.% of BmImTFSI. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies revealed the amorphous nature and morphology of these polymer electrolytes, respectively. The lower coherence length of the peak inferred the higher amorphous degree in these polymer matrices. Decreases in T_g and T_m indicate the flexibility of polymer backbone. The amorphous behavior of these ionic liquid-based gel polymer electrolytes are also enhanced as shown in differential scanning calorimetry (DSC) analysis. On the contrary, thermogravimetric analysis (TGA) divulges that the thermal stability of polymer electrolytes has been improved upon impregnation of BmImTFSI.     

Conductivity,thermal and infrared studies on plasticized polymer electrolytes with carbon nanotubes as filler

New composite polymer electrolytes (CPE) are prepared using solution-casting technique. The CPE are based on polyethylene oxide (PEO) and employ lithium hexafluorate (LiPF₆) as the doping salt, ethylene carbonate (EC) as the plasticizer and amorphous carbon nanotubes (αCNTs) as the filler. The crystallinity and ionic conductivity of the CPE are examined in this work. The conductivity increases from 10^?10 to 10^?5 S cm^?1 upon the addition of salt. The incorporation of EC and αCNTs into the salted polymer enhances the conductivity significantly to 10^?4 and 10^?3 S cm^?1. The Vogel–Tamman–Fulcher (VTF) plots suggest that the temperature dependence of conductivity is a thermally activated process. Differential Scanning Calorimetry (DSC) studies show that the melting transition temperature and crystallinity decrease upon the addition of salt, EC and αCNTs into the polymer electrolyte system. The complexation, nature and concentration of the various ionic species are examined using Fourier Transform Infrared Spectroscopy (FTIR). Scanning electron microscopy (SEM) images show the changes in morphologies of the composite polymer electrolytes. The application of CPE especially in batteries and the advantages of this composite are highly conductive and stable at elevated temperature.     

Effect of LiCF3SO3 on L-Chitosan/PMMA Blend Polymer Electrolytes

This paper focuses on the effect of lithium triflate (LiCF₃SO₃) on the structural and conduction properties of lauroyl (L)-chitosan/poly(metylmethacryalate) (PMMA)-based polymer electrolytes. Films of L-chitosan/PMMA blends and its complexes were prepared using a solution-casting technique. The ionic conductivity of the system was measured over a wide range of frequency between 50 Hz-1 MHz. Impedance plot for the samples demonstrates two well-defined regions. The disappearance of the high frequency semicircular region led to a conclusion that the current carriers are ions. Sample with 30 wt% of LiCF₃SO₃ showed the highest conductivity of 7.59 ± 3.64 × 10^?4 Scm^?1 at room temperature. This is consistent with the results obtained from infrared spectroscopy.     

Structure and lithium ion diffusion in lithium silicate glasses and at their interfaces with lithium lanthanum titanate crystals

Solid state lithium ion electrolytes are important to the development of next generation safer and high power density lithium ion batteries. Lithium containing glasses such as lithium silicate glasses have been widely studied due to their high ionic conductivity. Recently, lithium silicate glasses were introduced in polycrystalline lithium lanthanum titanate (LLT) ceramics as intergranular thin films between the crystalline grains to achieve higher lithium ion conductivities in these solid state electrolytes. In this work, we present investigations of the structure and diffusion behavior of lithium silicate glasses and their interfaces with LLT crystals using molecular dynamics simulations. The short and medium range structures of the lithium silicate glasses were characterized and the ceramic/glass interface models were obtained using MD simulations. Lithium ion diffusion behaviors in the glass and across the glass/ceramic interfaces, as well as the effect of atomic structure on diffusion behaviors, were investigated. It was found that there existed a minor segregation of lithium ions at the glass/crystal interface. The interface lithium ion diffusion energy barrier was found to be dominated by the glass phase.     

WO3-based electrochromic system with hybrid organic–inorganic gel electrolytes

Thin metal oxide films for a WO₃-based symmetric electrochromic system with a nickel oxide layer as the counter electrode have been prepared by spray pyrolysis on SnO₂:F coated soda-lime float glass, at a temperature of 670–720 °C and using metal acetylacetonates as precursors. The films have been characterized for composition and morphology by scanning electron microscopy equipped with an X-ray energy dispersive analyzer (SEM/EDAX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Electrochromic properties have been examined in the electrochemical cells of a smart window arrangement using lithium ion doped sol–gel derived organic–inorganic hybrid materials as electrolytes. Hybrids with room-temperature ionic conductivities of 10^?4–10^?3 Ω^?1 cm^?1 have been synthesized from tetraethyl orthosilicate (TEOS) with an addition of 35 mass % of organic compounds. Coloration-bleaching of WO₃ films with lithium ions from hybrid electrolytes has resulted in the desired modulating the properties in the visible and near infrared spectrum range. An XPS analysis has shown the presence of a lower oxidized tungsten oxide phase (WO_2.92) in the WO₃ film.     

Diaquobis-μ-(dimethylsulfoxo)bis(dimethylsulfoxo) dilithium tetraphenylborate

The structure of diaquobis--(dimethylsulfoxo)bis(dimethylsulfoxo)dilithium tetraphenyl- borate, [Li₂(Me₂SO)₄(H₂O)₂][BPh₄]₂, has been determined at 293 K. The compound crystallizes in the triclinic P-1 space group (a = 11.429(2) Å, b = 14.068(3) Å, c = 19.215(4) Å, = 69.31(3), = 88.98(3), = 89.03(3)). The lithium is coordinated to the oxygens of an aquo ligand, a terminal dimethylsulfoxo ligand, and two bridging dimethylsulfoxo ligands. The coordination geometry of each lithium is significantly distorted from a tetrahedron by the twisting of the plane containing the lithium ion and the two bridging dimethylsulfoxo oxygens relative to the plane containing the lithium ion and the terminal dimethylsulfoxo and aquo oxygen atoms. Hydrogen bonding between the aquo hydrogens and the phenyls of the tetraphenylborate anion is observed but does not result in a polymeric structure as has been observed in other lithium tetraphenylborate salts because of the 1:1 ratio of aquo ligands and tetraphenylborate anions.     

Growth and ionic conductivity of Li3 + x P1 − x GexO4 (x = 0.34) single crystals

Li_{3 + x} P_{1 ? x} Ge_xO₄ crystals (x = 0.34) with dimensions of about 3 × 3 × 5 mm³ were grown for the first time from flux. The conductivities of the crystals measured along three directions have close values and are equal to σ ≈ 1.8 × 10^?6 and 3.7 × 10^?2 Sm/cm at the temperatures 40 and 400°C, respectively (similar to the case of pure lithium phosphate, somewhat lower values of electric conductivity were measure along the b axis). The activation energy of conductivity is equal to 0.54 eV. A considerable increase in the conductivity of the solid solution in comparison with the conductivity of pure lithium phosphate is explained by the specific features of the lithium sublattice in the crystal structure of the λ-Li₃PO₄ type.     

Ion conducting corn starch biopolymer electrolytes doped with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Biodegradable corn starch-lithium hexafluorophosphate (LiPF₆) based biopolymer electrolytes were prepared by solution casting technique. Ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF₆) was doped into the polymer matrix. Upon addition of 50 wt.% BmImPF₆, the maximum ionic conductivity of (1.47 ± 0.02) × 10^− 4 Scm^− 1 was achieved due to its higher amorphous region. This result had been further proven in ATR-FTIR study. Frequency dependence of conductivity and dielectric studies reveal the occurrence of polarization at the electrolyte-electrode interface and thus form the electrical double layer, asserting the non-Debye characteristic of polymer electrolytes. This result is in good agreement with dielectric loss tangent study. Based on the changes in shift, changes in intensity, changes in shape and existence of some new peaks, attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) divulged the complexation between corn starch, LiPF₆ and BmImPF₆, as shown in the spectra.     

Electronic conductivity and structural chemistry in Li-Te-V oxide glasses

The electronic conductivity of the Li₂O-Te₂V₂O₉ glass system reveals that, even for high lithium content, electron hopping occurs between V⁴⁺ and V⁵⁺. The study of the V⁴⁺ content versus various syntheses shows that more than lithium content, the nature of the counter ion used in Li⁺ reagent and its decomposition behavior are responsible for the efficiency of the spontaneous V⁵⁺ reduction via a ‘sprouting’ phenomenon. The electron hopping process implies interconnection of VO_n polyhedra which are accessible for both V⁴⁺ and V⁵⁺ species. Such fact gives information about short and medium range ordering in the glasses. On the basis of the LiVTeO₅ crystal structure and in agreement with wide angle X-ray scattering experiments, a possible rearrangement bringing together VO₅ square pyramids is proposed to explain the electron hopping. Such proposal corresponds to a lithium network forming effect. It could explain why for Li/V>1 the electronic conductivity increases with lithium content while the V⁴⁺ amount remains low.     

Characterization of SBA-15 doped (PEO + LiClO4) polymer electrolytes for electrochemical applications

SBA-15 mesoporous material was prepared by the simple hydrothermal process and added to poly(ethylene oxide) (PEO) and lithium percholorate (LiClO₄) as a filler. X-ray Diffractometry (XRD), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) were used to determine the characteristics of the composite polymer electrolyte. The SEM of the electrolyte containing 10 wt% of SBA-15 confirms the highest miscibility and amorphous nature. SBA-15 doped (PEO + LiClO₄) polymer electrolytes have shown improved conductivity over the pure PEO and (PEO + LiClO₄) electrolyte. The mesoporous SBA-15 acted as crystal cores and fined the crystallites thus decreasing the crystallinity, which provided a much more continuous amorphous domain for Li⁺ ions to move easily in the (PEO + LiClO₄) electrolyte.     

Preparation and the proton conductivity of chitosan/poly(vinyl phosphonic acid) complex polymer electrolytes

This study describes the preparation and proton conductivity of novel polymer complex electrolytes consisting of chitosan and poly(vinylphosphonic acid), PVPA. The materials were prepared via in situ polymerization of vinyl phosphonic acid in the presence of chitosan at various monomer feed ratios with respect to d-glucosamine repeat unit. Homogeneous materials were produced and they were extensively characterized for their compositions by elemental analysis (EA), thermal properties by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the morphology by X-ray diffraction (XRD). The complexation of chitosan/PVPA via proton exchange reactions was confirmed by Fourier transform infrared (FT-IR). The methanol permeability of CHPVPA₅ was lower than Nafion^® 115. The water/methanol uptake was measured and the results showed that solvent absorption of the materials increased with increasing PVPA content in the matrix. The temperature dependence of the proton conductivity of the complex electrolytes follows VTF behavior at higher x. Proton conductivity of CHPVPA₅ was measured to be approximately 3 × 10⁻⁵ S/cm at 120 °C in the anhydrous state.     

Optical Absorption Spectrum of Co2+ Ion Impurities in Lithium Sodium Potassium Sulphate Single Crystal

Optical absorption spectrum of Co²⁺ ions doped in lithium sodium potassium sulphate single crystal has been studied at room and liquid nitrogen temperatures. The observed bands are assigned as transitions from the ground ⁴T_1g(F) to various excited quartet and doublet levels of Co²⁺ ion in octahedral symmetry. The splitting in one of the bands at liquid nitrogen temperature has been explained as due to spin-orbit interaction. All the observed band positions have been fitted with the parameters B, C, D_q and ζ.     

Syntheses and Crystal Structures of a Series of Manganese-Lanthanide-Sodium 12-Metallacrown-4 Dimers

A series of heterotrimetallic manganese-lanthanide-sodium dimer metallacrowns has been synthesized and characterized by single-crystal X-ray analysis: {LnNa[12-MC_{Mn(III)N(shi)}-4]}₂(iph)₄, where Ln^III?=?La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14), and Y (15); MC is metallacrown; shi^3? is salicylhydroximate; and iph^2? is isophthalate. The manganese(III) ions and shi^3? ligands generate the 12-MC-4 framework with one Ln^III and Na⁺ ion bound to each [12-MC_{Mn(III)N(shi)}-4] on opposite sides of the central MC cavity. The carboxylate groups of the isophthalate ligands bridge between the central Ln^III ion and each ring Mn^III ion, and the meta-arrangement of the carboxylate groups joins two LnNa[12-MC_{Mn(III)N(shi)}-4] units together to form the dimer through the Ln^III ions, which reside on the interior of the molecule. The identity of the central Ln^III ion slightly impacts the size the [12-MC_{Mn(III)N(shi)}-4] framework. As the crystal radius of the Ln^III ion increases from Lu^III (1.02 Å) to La^III (1.19 Å), the 12-MC-4 framework expands to accommodate the larger Ln^III ion as the MC cavity increases in size (0.53 Å for Lu^III to 0.58 Å for La^III) and the average cross cavity Mn^III-Mn^III and oxime oxygen-oxime oxygen distances also increase (Mn^III-Mn^III distances: 6.48 Å for Lu^III to 6.52 Å for La^III; O_oxime-O_oxime distances: 3.66 Å for Lu^III to 3.75 Å for La^III). In addition, the larger Ln^III ions reside further from the MC cavity as indicated by the Ln^III-oxime oxygen mean plane (O_oxMP) distance. The Ln^III-O_oxMP distance steadily decreases from La^III (1.7527(12) Å) to Lu^III (1.5575(15) Å).

Graphic Abstract

The complex {LaNa[12-MC_{Mn(III)N(shi)}-4]}₂(iph)₄(DMF)₆(H₂O)₂ is a dimer of [12-MC-4] molecules linked by four isophthalate anions