Ion Conducting Polymer Electrolyte Research Articles

Preparation and characterization of proton-conducting polymer electrolyte based on PVA, amino acid proline, and NH4Cl and its applications to electrochemical devices

Biodegradable solid polymer electrolytes based on PVA (polyvinyl alcohol) and amino acid (proline) with different molar mass percentages of ammonium chloride (NH4Cl) were prepared by solution-casting technique using distilled water as solvent. Their structural, thermal, vibrational, and electrical properties were studied. XRD analysis confirms the amorphous nature of the polymer electrolytes. DSC measurements show a decrease in Tg with increasing salt concentration. The FTIR analysis reveals the complex formation between the PVA, proline, and ammonium chloride. Transference numbers for the proton-conducting polymer electrolytes have been measured. The maximum ionic conductivity has been found to be 7.01 × 10−4 S/cm at ambient temperature for 75 Mwt% PVA;25 Mwt% proline:0.3 (m.m.%) of NH4Cl polymer electrolyte using AC impedance analyzer. The temperature-dependent conductivity of the polymer membranes obeys Arrhenius behavior. The highest ionic conductivity polymer electrolyte has low activation energy of 0.07 eV among the prepared polymer electrolytes. An electrochemical stability window of 3.10 V has been measured using linear sweep voltammetry for the highest ionic conducting membrane. The highest conductivity polymer electrolyte 75 Mwt% PVA:25 Mwt% proline:0.3 (m.m.%) NH4Cl has been used to construct a primary proton battery and fuel cell.

Composite Graphene/Blended Polymer of PEO/PVDF-HFP As Solid Polymer Electrolyte for Sodium Batteries

Solid polymer electrolytes (SPEs) are promising candidates for their application in electrochemical devices owing to its thermal and mechanical stability for application purposes [1-3]. The ionic conduction in polymer electrolytes occurs in amorphous phase where the ionic motion is coupled with the segmental motion above glass transition temperature. Among various polymers, the polyethylene oxide (PEO) has been studied extensively so far due to its high mechanical property and low barriers to bond rotation with ion efficiency [4,5]. Recently, the poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) has also greatly attracted as a polymer matrix with which provides mechanical stability (by PVdF) and improves ionic conductivity (by HFP component) [6-8]. In this work, we employed the blending polymer of PEO and PVdF-HFP to create a SPEs for sodium-ion battery application. Graphene addition aims to enhance ionic conductivity and mechanic properties of SPEs. Structure and morphology of polymer electrolytes were characterized by X-rays diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal properties of membrane were analyzed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Ionic conductivity and electrochemical stability of polymer membranes were also studied using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The battery performance was evaluated based on charge/discharge curve and sodium intercalation/deintercalation process. A comparison between Na-ion and Li-ion battery using SPEs was also performed.

(Invited) Mechanistic Details of Protonic Solar Cells Formed Via Covalent Modification of Passive Ion-Exchange Membranes with Photoacid Dye Molecules

Many electrochemical technologies require ion-conducting polymer electrolytes. These polymers are passive in that electric bias across them drives ion migration in the thermodynamically favored direction.1 Recently, my group engineered two important features into ion-selective polymer membranes to introduce the active function of photovoltaic action and demonstration of an ionic solar cell. These features were covalent bonding of photoacid dyes to the polymers such that absorption of visible light liberated protons, and polymers with charge-selective contacts to facilitate separation and collection of H+ and OH–.2,3 The most effective designs join a monopolar cation-selective polymer to a monopolar anion-selective polymer to form a bipolar membrane whose electrostatics and thermodynamics mimic those of a rectifying semiconductor pn-junction diode. Illumination from either side of a photoacid-modified bipolar membrane resulted in photoinduced deprotonation of photoacids followed by charge separation in a direction dictated by the built-in electrostatic asymmetry in the polymers. Performance optimization is underway to increase the state-of-the-art voltage to beyond 120 mV and state-of-the-art current to beyond 100 μA/cm2. The aim of these efforts is to gain a strong fundamental understanding of dye and material function using a variety of techniques. These include electrochemical impedance spectroscopy to quantify properties of capacitive space-charge regions; pulsed-laser spectroscopy to elucidate light-driven mechanisms of ion transfer and transport; finite-element numerical modeling to understand photoacid dye kinetics and drift–diffusion generation–recombination membrane physics; and optical, electron, and ion microscopies to elucidate materials morphology and function. Collectively, these photo-responsive polymers represent a new class of materials that use light to trigger changes in local pH and/or electrostatic potential. These local changes can be used to affect macroscopic processes such as direct solar desalination of salt water or triggering redox chemistry or chemical catalysis. Acknowledgment: This work is supported by a Moore Inventor Fellowship from the Gordon & Betty Moore Foundation, under Grant #5641.

Polymethacrylate-comb-copolymer electrolyte for solid-state energy storage devices

We report a highly ion-conductive polymer electrolyte, based on a poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate)-poly(oxyethylene methacrylate)-comb (PBE-comb) copolymer and the 1-ethyl-3-methylimidazolium dicyanamide (EMIM-DCA) ionic liquid, for use in a solid-state supercapacitor. Selective interactions between the poly(oxyethylene methacrylate) (POEM) chains and the EMIM-DCA induce the formation of a microphase-separated structure, as evidenced by Fourier-transform infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. The well-defined nanostructured morphology effectively suppresses the aggregation of EMIM-DCA to provide ion-transport pathways that facilitate the fast diffusion of mobile ions. The capacitance of the solid-state supercapacitor formed with the PBE/EMIM-DCA electrolyte (125.1Fg−1) was much greater than that of the conventional poly(vinyl alcohol) (PVA)/H3PO4 electrolyte (39.5Fg−1) due to its higher ionic conductivity and superior affinity for the electrode. The fast ion-diffusion properties of the PBE/EMIM-DCA electrolyte was confirmed by its high capacitance retention (70%) at a fast scan rate, significantly higher than that observed for the PVA/H3PO4 electrolyte. Moreover, the supercapacitor composed of the PBE/EMIM-DCA electrolyte showed considerable cycling stability (91.1% after 10,000 charge-discharge cycles). The PBE/EMIM-DCA electrolyte is therefore a promising candidate for use in high-performance solid-state supercapacitors and energy-storage systems.

Effects of the Solvent Evaporation Temperature on PVC Based Gel Polymer Electrolytes

The blade casting method was applied for producing PVC based gel polymer electrolytes. Effects of the solvent evaporation temperature on the ionic conductivity of polymer electrolytes were investigated though AC impedance measurements. The scanning electron microscope was used to observe the surface morphology of the polymer electrolytes. Lower solvent evaporation temperature was in favor of larger porous structure and higher ionic conductivity.

High-performance solid polymer electrolytes for lithium ion batteries based on sulfobetaine zwitterion and poly (ethylene oxide) modified polysiloxane

Herein we report a new high ionic conductivity and wide electrochemical window solid polymer electrolyte (SPE), which is developed via grafting sulfobetaine zwitterion (ZI) and poly (ethylene oxide) (PEO) chains on highly flexible polysiloxane backbone followed by crosslinking of tri(ethylene glycol) divinyl ether. The synergistic effect of zwitterion and PEO endows the SPE with an excellent ionic conductivity of 3.39 × 10−4 S cm−1 and the wide electrochemical stable window of 5.0 V (vs. Li/Li+) at room temperature. LiFePO4/Li half-cells with as-prepared solid polymer electrolyte present a high initial discharge capacity of 155 mAh g−1 and superior cycle stability with a capacity retention of 93% at 0.1 C after 100 cycles at 30 °C. In addition, LiNi0.5Mn1.5O4/Li half-cells employing such polymer electrolyte also deliver excellent cycle performance and stability. The above results indicate that the designed zwitterionic SPE appears to be a potential candidate for application in all-solid-state lithium-ion batteries.

Electric and Dielectric Properties of Sodium Ion Conducting Polymer Electrolyte

Electric and Dielectric Properties of Sodium Ion Conducting Polymer Electrolyte

Physical investigations on pure and KBr doped poly(vinyl alcohol) (PVA) polymer electrolyte films for solid state battery applications

Potassium ion conducting polymer electrolyte films were prepared based on poly(vinyl alcohol) (PVA) complexed with 5, 10 and 15 wt% potassium bromide (KBr) salt using solution-casting technique. X-ray diffraction and Fourier transform infrared spectroscopy studies were used to determine the complexation of the KBr salt with polymer structure. Differential scanning calorimetry was used to determine the melting temperatures and relative crystallinity values of pure PVA and PVA:KBr complexed films. The conductivity of the polymer films was measured using impedance spectroscopy. Room temperature ionic conductivity was found to be a maximum (1.23 × 10−5 S cm−1) for the (PVA:KBr) (85:15) complexed film, whose K+ ion transport number was found to be 0.97. Electrochemical cells were fabricated in the configuration K/(PVA:KBr)/(I2 + C + Electrolyte) and their discharge characteristics were studied under a constant load of 100 kΩ.

Effect of ethylene carbonate plasticizer on agar-agar: NH4Br-based solid polymer electrolytes

Proton-conducting polymer electrolytes based on biopolymer, agar-agar as the polymer host, ammonium bromide (NH4Br) as the salt and ethylene carbonate (EC) as the plasticizer have been prepared by solution casting technique with dimethylformamide as solvent. Addition of NH4Br and EC with the biopolymer resulted in an increase in the ionic conductivity of polymer electrolyte. EC was added to increase the degree of salt dissociation and also ionic mobility. The highest ionic conductivity achieved at room temperature was for 50 wt% agar/50 wt% NH4Br/0.3% EC with the conductivity 3.73 × 10−4 S cm−1. The conductivity of the polymer electrolyte increases with the increase in amount of plasticizer. The frequency-dependent conductivity, dielectric permittivity (e′) and modulus (M′) studies were carried out.

Single ion conducting lithium sulfur polymer batteries with improved safety and stability

A PEMA-graft-LiATFSI based single ion conducting polymer electrolyte enables superior electrochemical performance in both Li–Li symmetric cells and Li–S@PAN batteries.

A gel single ion conducting polymer electrolyte enables durable and safe lithium ion batteries via graft polymerization.

Concentration polarization issues and lithium dendrite formation, which associate inherently with the commercial dual-ion electrolytes, restrict the performance of lithium ion batteries. Single ion conducting polymer electrolytes (SIPEs) with high lithium ion transference numbers (t+ ≈ 1) are being intensively studied to circumvent these issues. Herein, poly(ethylene-co-vinyl alcohol) (EVOH) is chosen as the backbone and then grafted with lithium 3-chloropropanesulfonyl(trifluoromethanesulfonyl)imide (LiCPSI) via Williamson's reaction, resulting in a side-chain-grafted single ion polymer conductor (EVOH-graft-LiCPSI). The ionomer is further blended with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) by solution casting for practical use. The SIPE membrane with ethylene carbonate and dimethyl carbonate (EC/DMC = 1 : 1, v/v) as plasticizer (i.e., gel SIPE) exhibits an ionic conductivity of 5.7 × 10−5 S cm−1, a lithium ion transference number of 0.88, a wide electrochemical window of 4.8 V (vs. Li/Li+) and adequate mechanical strength. Finally, the gel SIPE is applied in a lithium ion battery as the electrolyte as well as the separator, delivering an initial discharge capacity of 100 mA h g−1 at 1C which remains at 95 mA h g−1 after 500 cycles.

Communication—Synthesis of Fluorine-Free Highly Ion Conductive Polymer Electrolyte Having Lithium Bissulfonimide Unit

A highly ion conductive polymer was designed based on lithium N-methanesulfonylvinylsulfoneimide (LiMSVSI), a new vinyl monomer consisting of the smallest skeleton except the lithium bisulfonimide moieties. Its copolymer with poly(ethylene glycol) methyl ether acrylate exhibited good ionic conductivity in the range of 10−4–10−5 S/cm.

A study on the interfacial stability of the cathode/polycarbonate interface: implication of overcharge and transition metal redox

In this work, we reported an unusual charge compensation through the parasitic reaction of polycarbonate, a high ionic conductivity polymer electrolyte, with transition metal ions (iron ions in LiFePO4) at cathodic interface, which leads to significant overcharge.

The effect of SiO2 additives on solid hydroxide ion-conducting polymer electrolytes: a Raman microscopy study.

The effect of SiO2 additives on the conductivity and longevity of an alkaline tetraethylammonium hydroxide (TEAOH)-poly(acrylamide) (PAM) polymer electrolyte was investigated. Electrochemical impedance spectroscopy (EIS) and Raman microscopy studies were performed for TEAOH-PAM with micro-sized (mSiO2) or nano-sized (nSiO2) additives under highly hydrated and under ambient conditions. At a high relative humidity (RH) of 75%, nSiO2 significantly increased the ionic conductivity of OH-, achieving 25 mS cm-1, while mSiO2 had little influence (10 mS cm-1). Further investigation at lower RH (45%) revealed that dehydration of TEAOH led to crystallization and lower conductivity of the polymer electrolytes. The degree and rate of crystallization in the different systems varied greatly: mSiO2 accelerated the process while nSiO2 delayed it. Using characteristic signatures obtained from Raman microscopy, a correlation between the ionic conductivity and the structural differences among these systems has been established and an explanation for the impact of the SiO2 additives has been proposed.

Pengaruh Alumina Terhadap Membran Blend Kitosan-Polivinil Alkohol- LitiumSebagai Membran Elektrolit Baterai

The research aim was to study the effect of adding % weight alumina on the conductivity of polymer electrolyte chitosan-PVA-lithium. The characterization of functional groups was determined using fourier transform infrared spectrometry (FTIR). The Ionic conductivity of polymer electrolyte chitosan-PVA-lithium-alumina was measured by using impedance spectroscopy. The measurement results show the polymer electrolyte with the addition of 5% alumina provides the highest ionic conductivity of 3.991 x 10-3S/cm. Battery characteristics of electrolyte polymer of chitosan-PVA-lithium with the addition of alumina have a voltage of 1.4 Volts compared to commercial batteries which have a voltage of 1.5 Volts. These results indicate that alumina can be used as a filler to increase the ionic conductivity.

Characterization of PVdF-HFP-based nanocomposite plasticized polymer electrolytes

Nanocomposite polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) have been prepared by using ammonium fluoride (NH4F) as salt, dimethylformamide as plasticizer and nanosize alumina (Al2O3) as filler. The ionic conductivity of polymer electrolytes has increased by four orders of magnitude (from 10−7 to 10−3 S/cm) with the addition of plasticizer. The conductivity of nanocomposite plasticized polymer electrolytes has increased by a factor of 3–4 with the addition of the nanofiller (alumina) along with an improvement in mechanical strength. The conductivity shows two maxima with the addition of alumina. X-ray diffraction studies have been carried out to check the crystallinity/amorphicity of polymer electrolytes. The small change in conductivity over the 30–130°C temperature range and conductivity remains nearly constant with time suggests that these electrolytes are desirable for their use in electrochemical devices such as batteries, fuel cells, sensors, supercapacitors and electrochromic devices. The activation energies of these electrolytes have also been calculated and correlated with conductivity results.

Thermal Analysis of 1-Ethyl-3-Methylimidazolium Trifluoromethanesulfonate Ionic Liquid to PEO-NaCF<sub>3</sub>SO<sub>3 </sub>Polymer Electrolyte

The objective of this study is to investigate the effect of ionic liquid to PEO-NaCF3SO3 solid polymer electrolyte. Sodium ion conducting polymer electrolyte films consisting of Polyethylene oxide (PEO) as a polymer host, Sodium trifluoromethanesulfonate (NaCF3SO3) as doping salt and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMiTF) as ionic liquid has been prepared by solution cast technique. Different amounts (5, 10, 15, 20, 25 and 30 wt. %) of EMiTF will be added to the optimized polymer-salt composition to develop PEO - NaCF3SO3 – EMiTF polymer electrolyte. Difference Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) indicated that the crystalline degree and the weight loss % of the electrolyte decrease with increasing the wt. % of the EMiTF respectively. The ionic transference number was found in the value of 0.95 which suggests that ions are the charge carriers.

Fluorene‐containing cardo and fully aromatic single ion conducting polymer electrolyte for room temperature, high performance lithium ion batteries

AbstractThe self‐assembly process between rigid fully aromatic single ion conducting polymer electrolytes (SIPEs) and flexible aliphatic binder for fabrication of macro‐scale porosity of membrane for enhancement of ionic conductivity has been demonstrated in our previous works. In this article, the bulky and rigid fluorene cardo groups are successfully introduced into the fully aromatic polymeric backbone to synthesize the fluorene‐containing cardo fully aromatic single ion conducting polymer electrolyte (fca‐SIPE). The synthesized fca‐SIPE is then blended with a flexible aliphatic PVDF‐HFP binder to prepare fca‐SIPE membrane via a solution cast method. By comparing with results of the previous works, in this case, not only the macro‐scale porous morphology derived from the self‐assembly process between PVDF‐HFP and fca‐SIPE, but also the interior nano‐scale lithium ion transport pathway throughout the free volume formed by the fluorene groups is obtained. The effect of the fluorene group on the key properties of membrane, such as ionic conductivity and battery performance, is systematically investigated. The excellent performance at high C‐rates at room temperature is demonstrated.

Solid Polymer Electrolytes Based on Ion Conductive Nanofiber Framework for Lithium Ion Battery

Solid polymer electrolyte (SPE) have been expected as high safety and reliable materials compared with conventional organic liquid electrolytes. In order to apply polymer electrolytes to all-solid-state Lithium Ion Battery (LIB), it is essential to improve their lithium ion conductivity and membrane stability. In this study, we focused on polymer nanofibers to overcome these issues on SPEs for LIB applications. Polymer nanofibers have unique characteristics such as high surface area, good mechanical property, and great material transport property [1]. We have reported fabrication, characterizations, and applications of various functional polymer nanofibers prepared by an electrospinning method [2]. Recently, we developed proton or anion conductive polymer nanofibers and revealed their outstanding ion conductive properties [3]. The nanofiber framework (NfF) composite membranes consisting of the ion conductive nanofibers and polymer electrolyte matrix showed remarkable fuel cell properties due to their improved ion conductivity, gas barrier property, and membrane stability [4]. Here presents our recent work on lithium ion conductive polymer nanofibers and their application to all-solid-state LIBs. The electrospinning method was attempted to fabricate lithium ion conductive NfFs composed of lithium salt and polymers bearing ethylene oxide units in their main or side chains. The lithium ion conductive NfF composite membranes were prepared by filling polymer electrolyte matrices into the voids of the NfFs. Electrochemical, thermal, and mechanical properties of the NfFs and NfF composite membranes were evaluated to demonstrate improved electrolyte characteristics. Fabrication and evaluation of all-solid-state LIBs based on the NfF composite membranes will also be reported. Acknowledgements This work is partially supported by JSPS KAKENHI (26410225), and a grant (Platform for Technology and Industry) from Tokyo Metropolitan Government, Japan.

Effect of temperature on electrochemical performance of ionic liquid based polymer electrolyte with Li/LiFePO4 electrodes

Poly ethylene oxide based polymer electrolytes containing salt lithium bis(trifluoromethylsulfonyl)imide and ionic liquid 1-butyl-3-methyl pyridinium bis(trifluoromethylsulfonyl)imide are synthesized. The prepared polymer electrolytes are found to be thermally stable up to 340–360°C. Ionic conductivity is observed ~2.5×10−5Scm−1 at 25°C and 2.3×10−4Scm−1 at 40°C for 30% IL containing polymer electrolyte. Also, ionic transference number>0.99 and cationic transference number ~0.41 with electrochemical window ~5.2V at 25°C is observed for the electrolyte containing 30% IL. The highest Li+ ion conducting polymer electrolyte is further optimised for battery application. The specific discharge capacity of the prepared cell (Li/polymer electrolyte/LiFePO4) is found to be 106mAhg−1 at 25°C and 160mAhg−1 at 40°C up to 25cycles with 0.1C current rate. The increment in discharge capacity at higher temperature may be due to the better electrode-electrolyte contact. Decrement in cell resistance is also observed at higher temperature.