Lithium Trifluoromethanesulfonate Research Articles

Effect of Swelling in Electrolyte Polymer Binder Positive Electrode on the Characteristics of Lithium-Sulfur Batteries

Lithium-sulfur (Li–S) batteries attract great attention of researchers due to their high theoretical energy density (2600 W∙h∙kg-1) and economic efficiency compared to state-of-art lithium-ion batteries [1]. The depth of the electrochemical reduction of sulfur and the cycle life of lithium-sulfur batteries are determined by the amount of electrolyte retained in the positive electrode [2]. In turn, the amount of electrolyte in the positive electrode is determined by its porosity and the ability of binders to swell in the electrolyte. Therefore, polymer binders used in the positive electrode can significantly affect the characteristics of lithium-sulfur batteries. The aim of the work was to study the effect of the swelling of polymer binders of the positive electrode in the electrolyte solution on the characteristics of lithium-sulfur batteries. The sulfur electrodes, with the composition of 70 wt.% Sulfur (99.5%, Russia), 10 wt.% multi-walled carbon nanotubes (Sigma Aldrich) and 20 wt% binder was the object of study. Polymeric binders were PEO (ММ 4∙106), PVDF-HFP (ММ 3∙105), LA-132. Lithium-sulfur cells were assembled as described in [3]. Electrolyte was1M LiCF3SO3 in sulfolane. Sulfolane is promising solvent for lithium–sulfur batteries. Electrolyte solutions based on sulfolane have high chemical and electrochemical stability [4], and moderate conductivity [5]. Sulfolane has a high flash point (166°C) [6]. Lithium trifluoromethanesulfonate was chosen as a support salt since electrolytes based on it have good scattering ability and provide lithium–sulfur cells with the smallest capacity depletion compared to electrolyte systems based on other salts [4]. Studies have shown that all investigated sulfur electrodes had good elasticity, mechanical strength and adhesion. Swelling of the electrode layer of sulfur electrodes was estimated by weight method at room temperature (23-25 °C) as follows. Pre-weighted sulfur electrodes were placed into the electrolyte solution for 48 hours. Then the sulfur electrodes were removed from the electrolyte, the excess of electrolyte was removed from the surface of the electrodes by a filter paper, and weighed. The mass of the electrolyte sorbed by the sulfur electrode was calculated as the difference in the masses of the sulfur electrodes after and before their storage into the electrolyte solution. It is established that the composition of the polymer binder has a significant effect on the swelling of the positive electrode in the electrolyte (Table). Sulfur electrodes containing PEO as a polymer binder can soak up to 2.8 µL/mAh(S). Sulfur electrodes containing PVDF-HFP and LA-132 can soak 1.5 and 1.1 µL/mAh(S), respectively. The discharge voltage profiles of lithium-sulfur cells with sulfur electrodes containing various polymeric binders differ significantly (Figure). The shape of the discharge voltage profile of lithium-sulfur cells, with the polymer binder PEO, is traditional: there are two voltage plateau: high voltage and low voltage. And in the case of polymer binders LA132 and PVDF-HFP, the discharge capacity corresponding to the end of the high-voltage stage is significantly lower than for cells with PEO binder, and the low-voltage plateau is almost indistinguishable. The difference in the swelling of sulfur electrodes containing various polymeric binders in the electrolyte solution explains the differences in the characteristics of the lithium-sulfur cells. This work was performed as part of a Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7) Russia and was also financially supported by the Russian Science Foundation (project No 17-73-20115).

Ion conducting polymer-silica hybrid ionogels obtained via non-aqueous sol-gel route

One pot synthesis of high ion-conducting polymer based organic-inorganic hybrid ionogels via non-aqueous sol-gel route is being reported here. These hybrid ionogel films have been obtained using copolymer, poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP), silica precursor, tetraethyl orthosilicate (TEOS), salt, lithium trifluoromethanesulfonate (LiTf) and ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIMTf). The use of non-aqueous sol-gel route facilitates the confinement of large amount of electrolyte solution in the hybrid matrix. The highest value of ionic conductivity achieved at room temperature for these hybrid ionogels (encompassing 65 wt% of electrolyte solution) is 3 mS/cm (comparable to that of liquid electrolyte), which is a desirable value for many electrochemical applications. Deconvolution of the ATR-IR spectra in the range 980–1100 cm−1 has provided information about the varying concentration of free ions (CF3SO3−) in the hybrid ionogels and evidence of ion-pair formation while the spectra in the 2900–3300 cm−1 range throws light on the interaction of the electrolyte solution (trapped in the organic-inorganic matrix) with the other constituents of the hybrid film (i.e., polymer and silica). These hybrid ionogels exhibit a wide electrochemical stability window (~4.63 V) and high thermal stability (~320 °C) along with increased amorphisity. The value of tLi+ has been found to be in the range. The value of tLi+ has been found to be in the range ~0.41 to 0.48 for all the films. The maximum value of tLi+ ~ 0.48 has been obtained for the hybrid ionogel film containing 60 wt% of electrolyte solution (PVdF-HFP/silica/ES-60). Mechanical properties indicate that higher amount of the electrolyte solution in the matrix reduces the mechanical strength. However, for films with same amount of electrolyte solution, the film without SiO2 has higher mechanical strength as compared to the one with SiO2.

Effect of Electrolyte on Performance of Electrochromic Films Including Plasma Modified V2O5 Composite

Vanadium pentoxide (V2O5) electrochromic material was modified by furan plasma polymerization method and electrochromic properties of the new V2O5/Polyfuran (PFu) composite material were examined in three different electrolytes (lithium perchlorate (LiClO4), lithium trifluoromethanesulfonate (LiTRIF), sodium perchlorate (NaClO4), which influence significantly their electrochemical and electrochromic features. The V2O5 and V2O5/PFu composite material were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDS), X-ray diffraction analysis and X-ray photoelectronspectroscopy (XPS) technique. Synergetic influences of composite films contributed to improve electrochromic performance that of V2O5. The best results were obtained with V2O5/PFu film in the presence of LiClO4/Propylene carbonate (PC) electrolyte that showed a high optical contrast of 32% and coloration efficiency of 31.3 cm2/C. The fastest reduction responses were obtained as 3.96 s, 2.24 s for V2O5 and V2O5/PFu films in 1 M NaClO4/PC electrolyte due to higher ionic conductivity. Simple and single-step plasma modification preparation technique of V2O5/PFu-based composite with excellent electrochemical behavior and improved electrochromic performance encourages in the development of high-performance flexible electrochromic applications.

Electrical, thermal, and structural studies on highly conducting additive-free biopolymer electrolytes for electric double-layer capacitor application

Biopolymer electrolytes consisting of poly(vinyl alcohol) (PVA) and lithium trifluoromethanesulfonate (LiTf) were prepared by solution casting technique. The ionic conductivity of polymer electrolyte is increased about seven orders of magnitude which is from 3.53 ± 0.01 × 10−10 to 2.87 ± 0.01 × 10−3 S cm−1 at ambient temperature with the addition of 40 wt% of LiTf. All the polymer electrolytes follow Vogel–Tamman–Fulcher (VTF) relationship which is associated with free volume theory. The complexation between PVA and LiTf salt is proven by Fourier transform infrared spectroscopy (FTIR) study. The glass transition temperature (Tg) of polymer electrolyte was decreased with the addition of LiTf as shown in differential scanning calorimetry (DSC) thermogram. The potential difference of the polymer electrolyte showed wider range, up to 4.6 V, as proven in linear sweep voltammetry (LSV) study. Electric double-layer capacitor (EDLC) cell was assembled using prepared polymer electrolytes and two identical activated carbon-based electrodes and its electrochemical properties were also investigated. The specific capacitance of 0.37 F g−1 was obtained for the EDLC with the most conducting polymer electrolyte.

Dendrite-Free Epitaxial Growth of Lithium for Efficient Charging of Li–O2 Batteries with Improved Cycle Life

Realization of rechargeable Li-metal batteries with high energy density is hindered by uneven Li deposition leading to dendrite formation during repeated cycles. Uncontrolled dendrite growth induces internal short-circuits which limit the cell lifetime and generate ohmic heat leading to catastrophic failure when a volatile electrolyte is used. Several strategies have been conceived by the researchers to suppress dendritic growth and delay the premature death of the cell. These efforts include using electrolyte additives to form a porous ion-conducting solid electrolyte interphase (SEI) layer on metal preventing further reaction,1 implementing solid electrolytes with optimum mechanical properties,2 designing a Li matrix,3 reducing local space charge on the Li surface,4 and so on. Although considerable improvements have been achieved from these earlier studies, microscopically smooth Li surface covered with thin and uniform SEI layers is yet to be realized. Alternatively, here we show an unprecedented dendrite-free epitaxial electrodeposition of Li in the presence of LiBr–LiNO3/glyme ether electrolyte under O2 atmosphere. Stripping and plating of Li metal was investigated by using a symmetrical Li│Li cell and it has been found that in 1 M LiNO3+0.05 M LiBr/tetraglyme electrolyte the plating of Li metal shows dendrite-free epitaxial growth up to a thickness of >20 μm which is clearly observed by the scanning electron microscopic (SEM) images and electron backscatter diffraction (EBSD) signal in Figure 1. The epitaxial growth of Li metal seems to be benefited from the synergistic effect of the anions Br− and NO3 − forming a thin and homogeneous Li2O–rich solid electrolyte interphase (SEI) layer which is formed during the very first discharge (stripping) process, where the corrosive nature of Br− removes the original thick passivation layer on Li surface which is then again oxidized (passivated) by the NO3 − to prevent further reactions with the electrolyte. Because of this, the SEI layer remains thin and facilitates the electropolishing effect and gets ready for the epitaxial electroplating of Li in the following charge process. Similar epitaxial growths of Li have been observed for both symmetrical Li│Li cell and Li–O2 full cell resulting in a much improved performance with longer cycle life.5,6 However, in contrast, LiNO3 alone or other lithium salts, such as Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium trifluoromethanesulfonate (LiTf), do not exhibit any epitaxial Li deposition. This demonstrates the bi-functional activity of the dual anion electrolyte LiNO3–LiBr towards dendrite-free epitaxial growth of Li. The role of deposition rate, effect of electrolyte solvent and a detailed mechanism of epitaxial growth will be discussed in the presentation.

Electrochemical Behavior of Stainless Steels in Highly Concentrated Electrolytes

Due to the superior mechanical properties and corrosion resistance of stainless steels, their application as exterior material and current collector has been examined. Recently, concentrated aqueous solutions of lithium salts are highly expected as a novel electrolyte because they allow the safe operation of lithium ion batteries, different from conventional organic solvent based electrolytes. Therefore, understanding on the electrochemical behavior of stainless steels in concentrated aqueous solutions is crucial to judge the applicability of stainless steels to lithium ion batteries. It is well-known that electrochemical behavior of metals in concentrated aqueous solution is different from that in dilute aqueous solution. The difference is considered to be attributed to chemical state of water molecules. In the present work, electrochemical behavior of stainless steels in highly concentrated aqueous solution of lithium trifluoromethanesulfonate was examined.

Silica-based ionogel electrolyte with porous flower-like structure enables safer lithium ion battery

The flammability and leakage of commercial lithium ion battery electrolytes greatly limit the safe application. All solid states electrolytes are considered as promising candidates but with low conductivity and interface issues. Quasi-solid state electrolyte with ionic liquid is believed to be a good choice. In this work, two kinds of ionogel quasi-solid state electrolytes with different lithium trifluoromethanesulfonate (LiOTf) and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salts are firstly synthesized by a fast sol-gel method. Porous silica structure with 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid confined is constructed. Different lithium salts make a difference on the microstructure of the two ionogel electrolytes. Both ionogel electrolytes exhibit a high ionic conductivity and are applied to the LiFePO4 coin cells. The ionogel electrolyte with LiOTf exhibits a good cycle performance. The extremely rich and cross-linked porous structures provide sufficient channels for ion transportation. This ionogel electrolyte overcomes the disadvantages of electrolyte leakage and flammability while allowing the good electrochemical performances. It can be considered as one of the potential candidates for lithium ion battery electrolyte.

ESR spectroscopic investigation of gamma-irradiated lithium trifluoromethanesulfonate

ABSTRACTThe effect of gamma radiation on lithium trifluoromethanesulfonate (LiTf) was investigated in detail using electron spin resonance (ESR) spectroscopy. The experimental spectra consisted of complex overlapped signals. Simulations of both the 1st- and 10th-day ESR spectra gave valuable information about the spectroscopic and structural features of radiation-induced radicals. More information about the qualitative and quantitative features of the radicals were gathered from the microwave power, storage time and dosimetric feature findings. In the light of the information obtained, four radicals were accepted to be produced after irradiation of LiTf.

Preparation and characterization studies of PMMA–PEO-blend solid polymer electrolytes with SiO2 filler and plasticizer for lithium ion battery

Solid polymer electrolyte systems comprising of polyethylene oxide (PEO) and polymethyl methacrylate (PMMA) as blended polymer host, lithium trifluoromethanesulfonate (LiCF3SO3) as dopant salt, ethylene carbonate (EC) as plasticizer, and silicon dioxide (SiO2) as inorganic filler were prepared by solution casting method. PMMA–PEO–EC–LiCF3SO3–SiO2-blend solid polymer electrolytes were prepared to study the blending effect of PMMA into PEO solid polymer electrolytes. All the resulted solid polymer electrolytes were characterized using electrochemical impedance spectroscopy (EIS), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) methods. In the present study, the XRD, FTIR, SEM, and DSC results show clear evidence of the miscibility of PMMA and PEO. The incorporation of PMMA into the PMMA–PEO-blend solid polymer electrolytes shows significant improvement on ionic conductivity when small amount of PMMA is used. The highest ionic conductivity of 2.6301 × 10−4 S/cm is achieved for 5 wt% PMMA and 95 wt% PEO-blend solid polymer electrolytes at room temperature. The ionic conductivity values are found to be decreased when a higher wt% of PMMA is added. Upon incorporation of 20 wt% of PMMA, the ionic conductivity values are found in range of 10−6 to 10−7 S/cm. This finding is comparable with the reported results for gel-type polymer electrolytes. Hence, the amount of PMMA used in the PMMA–PEO-blend systems is crucial in the preparation of PMMA–PEO-blend solid polymer electrolyte.

Silica Coated ZnFe2O4 Nanoparticles as Cathode Catalysts for Rechargeable Lithium‐Air Batteries

AbstractIn this work, the preparation and structural characterization of a novel material consisting of silica‐coated zinc ferrite (ZnFe2O4) nanoparticles as cathode catalysts for nonaqueous lithium‐air batteries (LABs) are presented for the first time. ZnFe2O4 nanoparticles (NPs) were prepared by the normal micelles method, using oleic acid as the capping agent and then coating them with silica, via a reverse microemulsion method, with various thicknesses. The colloidal ZnFe2O4 NPs and silica‐coated ZnFe2O4 NPs were characterized by TEM and powder XRD. The particle size of bare ZnFe2O4 NPs was calculated to be 5.8 nm by both TEM image and XRD pattern. They were then coated by silica with layer thicknesses of 9, 11, and 13 nm. The performances of bare and silica‐coated ZnFe2O4 NPs were evaluated as cathode catalysts for LABs using 1 M lithium trifluoromethanesulfonate (TFMS) in tetraethylene glycol dimethyl ether (TEGDME) as the electrolyte. The primary discharge/charge capacities of bare ZnFe2O4 NPs and ZnFe2O4 NPs with silica‐shell thicknesses of 9, 11, and 13 at 0.1 mA cm−2 were found to be 3300, 4300, 6200 and 5000 mAh g−1, respectively. The overpotential is almost 0.5 V, decreased by silica coating with a thickness of 11 nm, whereas there was no difference at other thicknesses. Cyclability with a discharge capacity of 1000 mAh g−1 was observed for at least 45 cycles for silica‐coated ZnFe2O4 NPs with a shell thickness of 11 nm.

High capacity semi-liquid lithium sulfur cells with enhanced reversibility for application in new-generation energy storage systems

Semi-liquid configuration of sulfur cell is proposed as simple strategy to develop high-energy lithium battery. Two solutions of Li2S8 in diethylene glycol dimethyl ether (DEGDME), containing either lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) or lithium trifluoromethansulfonate (LiCF3SO3) and lithium nitrate (LiNO3), are studied as catholytes for Li/S cells exploiting the polysulfides electrochemical reaction at about 2.2 V vs. Li+/Li. X-ray photoelectron spectroscopy (XPS) and thermal analyses, respectively, reveal composition and high-temperature stability of the catholyte solutions. Ad hoc study conducted by impedance spectroscopy, voltammetry, and galvanostatic techniques suggests well suitable characteristics in terms of Li+-transport ability, electrochemical stability window, and electrode/electrolyte interphase features. Cells with sulfur loading ranging from about 3 to 6 mg cm−2 into the solution are successfully studied with remarkable performances in terms of current rates, efficiency and cycle life. Hence, the lithium cells based on the catholyte deliver maximum capacity of the order of 1100 mAh gS−1 at C/10 rate and stable capacity of about 800 mAh gS−1 at C/3 rate with Coulombic efficiency exceeding 99%. Therefore, the catholyte solutions studied herein are considered as a very promising candidates for high-energy storage in next generation systems, such as the intriguing hybrid and electric vehicles.

Influence of binary lithium salts on 49% poly(methyl methacrylate) grafted natural rubber based solid polymer electrolytes

Effect of binary lithium salts (lithium tetrafluoroborate, LiBF4 with lithium trifluoromethanesulfonate, LiCF3SO3) and (lithium tetrafluoroborate, LiBF4 with Lithium iodide, LiI) as charge carriers in solid polymer electrolyte based 49% poly(methyl methacrylate) grafted natural rubber (MG49) for Li-ion battery application has been investigated. The polymer electrolytes were prepared by solution casting technique. The effect of binary lithium salts on chemical interaction, structural, thermal studies, ionic conductivity and ion transference number of MG49 films are analyzed by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS). Infrared analysis indicated the interaction occurred between Li ions and oxygen atoms at the carbonyl group (CO) and the ether group (COC) on methyl methacrylate (MMA) segments. XRD studies exhibited a reduction of the MMA peak intensity at 29.5° after the addition of different ratios of binary Li salts due to the plasticizing effect of the salts. The larger anion size tends to create bigger free volume in the polymer electrolyte. In addition, this confirms that the degree of crystallinity of the electrolyte films is reduced leading to enhancement of ionic conductivity. DSC results revealed the highest conductivity sample has the lowest Tg implying the ions can flow with more ease throughout the polymer chain. The ratios of LiBF4:LiI presenting the higher overall performance in terms of ionic conductivity comparing to LiBF4:LiCF3SO3 ratios in MG49. The highest room temperature conductivity was obtained at 1.89 × 10−6 S cm−1 for (30:70) LiBF4:LiI percentages ratio. Moreover, tion is observed to increase with the ionic conductivities.

Synthesis and characterization of radiation crosslinked nano silver- polyvinyl alcohol/polyethylene oxide composites

Poly (vinyl alcohol)/poly (ethylene oxide) (PEO/PVA) blends were modified by gamma irradiation in the presence of acrylic acid (AAc) monomer. The modified PVA/PEO blends were then complexed with silver nitrate salt and lithium trifluoromethanesulfonate. Transmission electron microscopy was used to determine the distribution as well as the particle size of the silver nanoparticles (NP) formed in the matrix. The UV–vis absorbance spectra of the prepared grafted nanocomposite membranes confirmed the formation of Ag NP based on their surface plasmon band at 438 nm. The electrical properties of the blended electrolyte polymer films were characterized and discussed.

Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries.

Glycol ethers, or glymes, have been recognized as good candidates as solvents for lithium–air batteries because they exhibit relatively good stability in the presence of superoxide radicals. Diglyme (bis(2-methoxy-ethyl)ether), in spite of its low donor number, has been found to promote the solution mechanism for the formation of Li2O2 during the discharge reaction, leading to large deposits, that is, high capacities. It has been suggested that lithium salt association in these types of solvents could be responsible for this behavior. Thus, the knowledge of the speciation and transport behavior of lithium salts in these types of solvents is relevant for the optimization of the lithium–air battery performance. In this work, a comprehensive study of lithium trifluoromethanesulfonate (LiTf) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,2-di-methoxyethane (DME) and diglyme, over a wide range of concentrations, have been performed. Consistent ion pairs and triplet ions formation constants have been obtained by resorting to well-known equations that describe the concentration dependence of the molar conductivities in highly associated electrolytes, and we found that the system LiTf/DME would be the best to promote bulky Li2O2 deposits. Unexpected differences are observed for the association constants of LiTf and, to a lesser extent, for LiTFSI, in DME and diglyme, whose dielectric constants are similar. Molecular dynamics (MD) simulations allowed us to rationalize these differences in terms of the competing interactions of the O-sites of the ethers and the SOx groups of the corresponding anions with Li+ ion. The limiting Li+ diffusivity derived from the fractional Walden rule agrees quite well with those obtained from MD simulations, when solvent viscosity is conveniently rescaled.

Modifying the thermal and mechanical properties of poly(lactic acid) by adding lithium trifluoromethanesulfonate

The effect of the addition of lithium trifluoromethanesulfonate (LiCF3SO3) on the linear viscoelastic properties, crystallization behavior, and mechanical properties of poly(lactic acid) (PLA) was studied. The glass transition temperature (Tg) was enhanced by adding LiCF3SO3, without any loss of transparency of the PLA. This was attributed to the ion-dipole interaction between the lithium cation and oxygen atom in the PLA carbonyl group. The interaction weakened at higher temperature. Consequently, the rheological terminal region was clearly detected, which suggested that the system possessed good melt-processability. The Young’s modulus and yield stress at room temperature were also enhanced by the addition of LiCF3SO3, although the toughness was reduced due to the brittle failure. Finally, the presence of LiCF3SO3 retarded the crystallization of PLA, because the segmental motion of the PLA chains was reduced.

Control of optical and mechanical properties of poly(methyl methacrylate) by introducing lithium salt

We investigated the effect of lithium trifluoromethanesulfonate (LiCF3SO3) on the optical properties of poly (methyl methacrylate) (PMMA), known as a glassy transparent polymer. The absolute values of the stress-optical coefficients in both the glassy and rubbery states were found to be reduced by the addition of LiCF3SO3. Furthermore, the linear coefficient of thermal expansion of the blend containing 10 wt.% of LiCF3SO3 was lower than that of pure PMMA, suggesting that the birefringence caused by thermal expansion in laminated display systems would be greatly reduced. These results indicate that PMMA/LiCF3SO3 is an appropriate blend for optical films used for liquid crystal displays.

Enhancement of the glass transition temperature of poly(methyl methacrylate) by salt

We investigated the effects of two metal salts, lithium trifluoromethanesulfonate (LiCF3SO3) and lithium bromide (LiBr), on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA). Both LiCF3SO3 and LiBr greatly enhanced the Tg of PMMA under dry conditions. However, once the sample films were exposed to humidity, the PMMA containing LiCF3SO3 absorbed a large amount of water, which acts as a plasticizer. As a result, the Tg shifted to a lower temperature, which limits the utility of this polymer in industrial applications. In contrast, the Tg of PMMA containing LiBr was minimally affected by the absorption of water. This phenomenon can be explained by the ion–dipole interactions with the small number of dissociated lithium cations. Tg of PMMA was greatly enhanced by introducing ion–dipole interaction between lithium cations and carbonyl groups in PMMA as pseudo crosslinking points.

Preparation and characterization of PEO-based composite gel-polymer electrolytes complexed with lithium trifluoro methane sulfonate

AbstractChitosan has been successfully incorporated as a filler in a polyethylene oxide (PEO) and lithium trifluoromethanesulfonate (LiCF3SO3) matrix with a combination of plasticizers, namely 1,3-dioxolane (DIOX) and tetraethylene glycol dimethylether (TEGDME). The composite gel-polymer electrolyte (CGPE) membranes were prepared by solution casting technique in an argon atmosphere. The prepared membranes were subjected to SEM, TG/DTA and FT-IR analyses. A Li/CGPE/Li symmetric cell was assembled and the variation of interfacial resistance was measured as a function of time. The lithium transference number (Li+t) was measured and the value was calculated as 0.6 which is sufficient for battery applications. The electrochemical stability window of the sample was studied by linear sweep voltammetry and the polymer electrolyte was found to be stable up to 5.2 V.

Effect of lithium salt addition on the structure and optical properties of PMMA/PVB blends

The effect of the lithium trifluoromethanesulfonate (LiCF3SO3) addition on the structure and properties for binary blends of poly(methyl methacrylate) (PMMA) and a random copolymer composed of vinyl butyral and vinyl alcohol, that is denoted as PVB in this paper, was evaluated. Although PMMA and PVB are immiscible, the LiCF3SO3 addition enhances the compatibility/miscibility by the ion-dipole interaction between lithium cation and both polymer chains. Only single peak ascribed to the glass-to-rubber transition is detected in the tensile loss modulus curve for PMMA/PVB/LiCF3SO3 (70/30/20), although there are distinct double peaks for PMMA/PVB (70/30). This result demonstrates that the salt, LiCF3SO3, acts as a compatibilizer. Furthermore, the salt addition enhances the storage modulus in the glassy region and the heat resistance due to the high-temperature-shift of glass transition temperature. The blend containing LiCF3SO3 is highly transparent and shows a significantly small value of the stress-optical coefficient in the glassy state, which are required for various optical films used for display, such as polarizer protective film.

Facile and scalable fabrication of polymer-ceramic composite electrolyte with high ceramic loadings

Solid state electrolytes are a promising alternative to flammable liquid electrolytes for high-energy lithium battery applications. In this work polymer-ceramic composite electrolyte membrane with high ceramic loading (greater than 60 vol%) is fabricated using a model polymer electrolyte poly(ethylene oxide) + lithium trifluoromethane sulfonate and a lithium-conducting ceramic powder. The effects of processing methods, choice of plasticizer and varying composition on ionic conductivity of the composite electrolyte are thoroughly investigated. The physical, structural and thermal properties of the composites are exhaustively characterized. We demonstrate that aqueous spray coating followed by hot pressing is a scalable and inexpensive technique to obtain composite membranes that are amazingly dense and uniform. The ionic conductivity of composites fabricated using this protocol is at least one order of magnitude higher than those made by dry milling and solution casting. The introduction of tetraethylene glycol dimethyl ether further increases the ionic conductivity. The composite electrolyte's interfacial compatibility with metallic lithium and good cyclability is verified by constructing lithium symmetrical cells. A remarkable Li+ transference number of 0.79 is discovered for the composite electrolyte.