Ionic Liquid Polymer Electrolyte Research Articles

A novel and shortcut method to prepare ionic liquid gel polymer electrolyte membranes for lithium-ion battery

The ionic liquid polymer electrolyte (IL-PE) membrane is prepared by ultraviolet (UV) cross-linking technology with polyurethane acrylate (PUA), methyl methacrylate (MMA), ionic liquid (Py13TFSI), lithium salt (LiTFSI), ethylene glycol dimethacrylate (EGDMA), and benzoyl peroxide (BPO). N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py13TFSI) ionic liquid is synthesized by mixing N-methyl-N-propyl pyrrolidinium bromide (Py13Br) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The addition of Py13TFSI to polymer electrolyte membranes leads to network structures by the chain cross-linking. The resultant electrolyte membranes display the room temperature ionic conductivity of 1.37 × 10−3 S cm−1 and the lithium ions transference number of 0.22. The electrochemical stability window of IL-PE is about 4.8 V (vs. Li+/Li), indicating sufficient electrochemical stability. The interfacial resistances between the IL-PE and the electrodes have the less change after 10 cycles than before 10 cycles. IL-PE has better compatibility with the LiFePO4 electrode and the Li electrode after 10 cycles. The first discharge performance of Li/IL-PE/LiFePO4 half-cell shows a capacity of 151.9 mAh g−1 and coulombic efficiency of 87.9%. The discharge capacity is 131.9 mAh g−1 with 95.5% coulombic efficiency after 80 cycles. Therefore, the battery using the IL-PE exhibits a good cycle and rate performance.

Ionic liquid integrated polyethylene glycol (PEG)-based quasi-solid electrolyte for efficiency enhancement of dye-sensitized solar cell

We are presenting herein the effect of using three different cell electrolytes namely: (a) propylene carbonate containing 0.2 M LiI and 0.02 M I 2; (b) a polymer electrolyte, same as (a) having polyethylene glycol (PEG) as polymer matrix; and (c) polymer electrolyte same as (b) with added ionic liquids, 1, 2-dimethyl-3-propylimidazolium iodide or 1-ethyl-3-methylimidazolium iodide on the performance of TiO2-based dye-sensitized solar cells (DSSCs). Electrolytes were structurally characterized using FTIR spectra, and their thermal stability was studied through TGA in the temperature range of 30–600 °C. Fabricated cells with varied composition of the cell electrolyte were assessed for their electrical outputs (J SC, V OC, η etc.) and EIS characteristics. Ionic liquid imbibed polymer electrolyte demonstrated improved thermal stability and higher room temperature ionic conductivity of 4.48 mS cm−1. DSSC composed of the polymer electrolyte with 1-ethyl-3-methylimidazolium iodide has shown an open-circuit voltage V oc = 0.75 V, a short-circuit current density J sc = 3.61 mA/cm2, fill factor FF = 0.51, and overall conversion efficiency η = 1.6% under irradiance of 100 mW cm−2. The conversion efficiency was enhanced by 60% with added ionic liquid compared to DSSC employing PEG-based polymer electrolyte. An increase in charge-transfer resistance (R ct) with increasing PEG concentration in the cell electrolyte from 20 to 60% and decrease with the addition of ionic liquids were observed. The cell performance at elevated temperatures was assessed by determining the photocurrent–potential curves for the cells with different electrolytes at temperatures ranging from 30 to 60 °C. The temperature variation resulted in strong influence on J SC, but the effect over V OC was insignificant.

Poly(vinyl chloride) Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries

Non-flammable electrolytes have been extensively studied to improve the safety of energy storage devices. In this study, a new ionic liquid polymer electrolyte (ILPE) prepared by a cast technique using poly(vinyl chloride) (PVC) as the host polymer was examined for sodium secondary batteries. The ILPE containing 50 wt% of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide [C2C1im][FSA] ionic liquid showed an ionic conductivity of 5.6 mS cm−1 at 318 K. It remains stable up to 517 K based on 5 wt% loss. Stable sodium metal electrodeposition/dissolution was observed at the cathodic limit of the electrochemical window for the ILPE containing Na[FSA] ([C2C1im][FSA]:Na[FSA]:PVC = 2.0:1.0:1.0 w/w). The anodic limit was observed at around 4.7 V vs. Na+/Na on a Pt working electrode, while on an Al working electrode a higher anodic stability owing to passivation was observed. In the Na/[C2C1im][FSA]-Na[FSA]-PVC/-Na2FeP2O7-cell with the theoretical capacity of 97 mAh g−1, a reversible capacity of 92 mAh g−1 was obtained at 363 K for the Na2FeP2O7 positive electrode. These results suggest great potential of this PVC-based ILPE for constructing very safe sodium secondary batteries.

A novel ionic liquid polymer electrolyte for quasi-solid state lithium air batteries

A novel ionic liquid polymer electrolyte with enhanced electrochemical properties is developed for improved lithium–air battery performance.

Novel development towards preparation of highly efficient ionic liquid based co-polymer electrolytes and its application in dye-sensitized solar cells

Ionic liquid polymer electrolytes (ILPE) were prepared with poly(1-vinylpyrrolidone-co-vinylacetate) P(VP-co-VAc) copolymer, tetrahexylammonium iodide (THAI) salt and 1-butyl-3-methylimidazolium iodide (BMII), a room temperature ionic liquid (RTIL). The ILPEs were characterized using electrochemical impedance spectroscopy (EIS) analysis, X-ray diffraction (XRD) studies, Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). The highest ionic conductivity obtained was 1.05 × 10−3 S cm−1 at room temperature in ILPE3 which is the sample incorporated with 80 wt% of BMII. FTIR analysis proved the formation of complexes in between the copolymer, salt and ionic liquid. XRD studies have shown that ILPE3 has the optimum amorphous nature. The ILPE based dye sensitized solar cell (DSSC) was assembled by sandwiching the ILPE in between the nanoporous TiO2 working electrode and Pt-coated counter electrode and thus subjected to device photovoltaic characterization. The DSSC with ILPE3 as its electrolyte has shown the highest power conversion efficiency (η) with a value of 4.93% with short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 12.37 mA cm−2, 0.69 V and 0.58, respectively. Temperature dependence studies has been done on the DSSCs to understand effect of the cell temperature on the performances of the DSSCs. EIS studies of the DSSCs shows that the ILPE is having higher diffusion coefficient compared to the GPE.

Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries

The development of non-flammable electrolytes has been extensively studied to reduce the drawbacks caused from organic solvents. In this study we have successfully demonstrated the use of Ionic Liquid Polymer Electrolyte (ILPE) as a separator for sodium ion battery by using polyvinyl chloride (PVC), in combination with the previously reported ionic liquid electrolyte, Na[FSA]-[C2C1im][FSA] (FSA = bis-(fluorosulfonyl)amide and C2C1im = 1-ethy-3-methylimidazolium)1. The ILPE was prepared by casting method in which PVC acts as a host polymer. The different ratio of [C2C1im][FSA] was added into the THF solution of PVC/NaFSA (1:1). The highest ionic conductivity was achieved with addition of 42.9% ionic liquid into the system which resulted in 1.49 mS/cm at 25 °C. The deposition and dissolution of Na metal has been observed around 0 V vs Na/Na+ by cyclic voltammetry. The reversible capacity of 92 mA g-1 was obtained at 363 K for a Na2FeP2O7 positive electrode in the Na/PVC-Na[FSA]-[C2C1im][FSA]/ Na2FeP2O7-cell (theoretical value is 97 mA g-1). This result suggests that the ILPE is a promising separator for sodium secondary battery where safety and cost are main concern. 1. Matsumoto, K.; Hosokawa, T.; Nohira, T.; Hagiwara, R.; Fukunaga, A.; Numata, K.; Itani, E.; Sakai, S.; Nitta, K.; Inazawa, S., The Na[FSA]–[C2C1im][FSA] (C2C1im+:1-ethyl-3-methylimidazolium and FSA−:bis(fluorosulfonyl)amide) ionic liquid electrolytes for sodium secondary batteries. Journal of Power Sources 2014, 265, 36-39.

Challenges and Issues Facing Lithium Metal for Solid State Rechargeable Batteries

Research on lithium metal combined with polymer electrolyte in lithium rechargeable batteries was started in 1979. Since that time, lithium battery research has expanded worldwide. Several new polymers, solid electrolytes and ionic liquids with improved conductivity were identified. These advances resulted from a better understanding of the major parameters controlling ion migration, such as favorable polymer structure, phase diagrams between solvating polymers and lithium salts, and the development of new lithium counter-anions. In spite of the progress so far, the quest for a highly conductive dry polymer at room temperature is still not available. However, effort is continuing, and all-lithium polymer battery (LPB) developers presently face the challenge of whether to heat the polymer electrolyte to enable high-power performance, as required for electric vehicles and energy storage. LPB developers have explored both the high-temperature and low-temperature options. The commercial use of lithium metal/polymer batteries has been delayed because of the adverse effects of dendrites on the surface of the lithium electrodes, and the difficulty in finding a polymer that has both the mechanical strength and ionic conductivity required in a solid electrolyte. However, recent strategies have emerged to overcome these difficulties, and now these batteries are currently an option for different applications, including electric cars.In this presentation, we review these strategies and discuss the different promising routes that should result in further progress on lithium metal/polymer batteries in the near future. This presentation also discusses the challenges and opportunities in developing thin lithium negative electrodes with stable SEI layers for three battery technologies using: All solid-state Li-sulfur batteries Rechargeable lithium batteries containing dry polymer and ionic liquid-polymer electrolytes 3. Li-air batteries. In addition, we will discuss the safety of lithium, dendrite mechanism, interface phenomena, side reactions, protection of lithium metal, and lithium alloys that are relevant to lithium batteries. Acknowledgement: The author thanks the SCE IREQ and LTE Shawinigan teams for helpful discussion.

A Piperidinium-Based Ester-Functionalized Task-Specific Ionic Liquid As Electrolytes in Li/LiFePO4 Batteries

Lithium batteries are the most attractive candidate to replace the traditional energy resources due to their high working voltage, high specific energy and long cycle life [1,2]. However, the widely use have been limited by their safety issues, especially under the condition of abusing or overcharging. In order to solve this issue, it is significant to screen a safe material as lithium batteries electrolyte.Room temperature ionic liquids (RTILs) have aroused much attention for use in lithium batteries, owing to their low volatility, inflammability, wide electrochemical window and high ionic conductivity [3]. Particularly, their excellent thermal stability makes them key to solve the safety issues of lithium batteries at high temperatures and their physicochemical properties can be tuned by introducing functionalized groups onto the cation or anion of RTILs. The functionalized task-special ionic liquids can reduce the viscosity and enhance their ionic conductivity of RTILs. In this study, a piperidinium-based ionic liquid, N-methyl-N-methoxycarbonylpiperidinium bis(trifluoromethanesulfonyl)imide ([MMOCPip][TFSI]), was synthesized by anion exchange reaction and used as an additive to electrolyte of Li-ion battery. The electrochemical performance of the electrolytes had been evaluated by electrochemical tests, such as the line sweep voltammetry, cyclic voltammetry and impedance spectroscopy.The N-methyl-N-methoxycarbonylpiperidinium bis(trifluoromethanesulfonyl)imide ([MMOCPip][TFSI]) ionic liquid was prepared by mixing equimolar N-methyl-N-methoxycarbonylpiperidinium bromide ([MMOCPip][Br]) and bis(trifluoromethanesulfonyl)imide lithium at room temperature in deionized water and by stirring for several hours until a hydrophobic [MMOCPip][TFSI] layer was formed below the water phase [4]. The ionic conductivity of [MMOCPip][TFSI] was 0.77 mS·cm-1 (25℃) and 2.41 mS·cm-1 (60℃), however, after adding 0.1 M LiTFSI, the ionic conductivity decreased to 0.51 mS·cm-1 (25℃) and 1.85 mS·cm-1 (60℃), respectively. The electrochemical window was 0.5 V~5.8 V (vs. Li+/Li), which was enough widely that could be used as common electrode material. The Li-ion transference number of ionic Liquid electrolyte containing 0.1 M LiTFSI was 0.56. The battery tests indicated that the [MMOCPip][TFSI] obviously improved the cyclability of the LiFePO4 cell. For the Li/ LiFePO4 half-cells, after 20 cycles at room temperature at 0.1 C, the discharge capacity was 109.7 mAh·g-1 with 98.7% capacity retention in the [MMOCPip][TFSI]/0.1 M LiTFSI electrolyte. The good electrochemical performance demonstrated that the [MMOCPip][TFSI] could be used as electrolyte additive for lithium batteries. Keywords: Ionic liquid; Li-ion battery; Ionic conductivity; Transference number Reference: [1] Wongittharoma N, Wang CH, Wang YC, Fey GTK, Li HY, Wu TY, Lee TC, Chang JK (2014). Charge-storage performance of Li/LiFePO4 cells with additive incorporated ionic liquid electrolytes at various temperatures. J Power Sources. 260: 268–275.[2] Yang J, Zhou XY, Zou YL, Tang JJ (2011). A hierarchical porous carbon material for high power, lithium ion batteries. Electrochim Acta. 56: 8576–8581.[3] Pandian S, Raju SG., Hariharan KS, Kolake SM, Park DH, Lee MJ (2015). Functionalized ionic liquids as electrolytes for lithium-ion batteries. J Power Sources. 286: 204-209. [4] Yang PX, Cui WY, Li LB, Liu L, An MZ (2012). Characterization and properties of ternary P(VdF-HFP)-LiTFSI-EMITFSI ionic liquid polymer electrolytes. Solid State Sciences. 14(5), 598–606. Figure 1

Ionic Liquid Polymer Electrolyte Based on Bis(fluorosulfonyl)Amide for Sodium Secondary Batteries

A new ionic liquid polymer electrolyte (ILPE) has been prepared for sodium secondary batteries. The ILPE is prepared by using a cast technique in which poly(vinyl chloride) used as a host polymer. The ILPE shows an ionic conductivity of 5.6 mS cm-1 at 318 K with 50 wt% of bis(fluorosulfonyl)amide ionic liquid. The stability of the ILPE reached 473 K based on 5 wt% loss. Sodium metal electrodeposition/dissolution was observed at the cathodic limit of the electrochemical window.

Ionic liquid doped PEO-based solid polymer electrolytes for lithium-ion polymer batteries

The influence of adding the room-temperature ionic liquid 1-ethyl-3-methyllimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) to poly(ethylene oxide) (PEO)–lithium difluoro(oxalato)borate (LiDFOB) solid polymer electrolyte and the use of these electrolytes in solid-state Li/LiFePO4 batteries has been investigated. Different structural, thermal, electrical and electrochemical studies exhibit promising characteristics of these polymer electrolyte membranes, suitable as electrolytes in rechargeable lithium-ion batteries. The crystallinity decreased significantly due to the incorporation of ionic liquid, investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The ion–polymer interaction, particularly the interaction of cations in LiDFOB and ionic liquid with ether oxygen atom of PEO chains, has been evidenced by FT-IR studies. The polymer electrolyte with ∼40 wt% of ionic liquid offers a maximum ionic conductivity of ∼1.85 × 10−4 S/cm at 30 °C with improved electrochemical stabilities. The Li/PEO-LiDFOB-40 wt% EMImTFSI/LiFePO4 coin-typed cell cycled at 0.1 C shows the 1st discharge capacity about 155 mAh g−1, and remains 134.2 mAh g−1 on the 50th cycle. The addition of the ionic liquid to PEO20-LiDFOB polymer electrolyte has resulted in a very promising improvement in performance of the lithium polymer batteries.

Flexible thin-film battery based on solid-like ionic liquid-polymer electrolyte

The development of high-performance flexible batteries is imperative for several contemporary applications including flexible electronics, wearable sensors and implantable medical devices. However, traditional organic liquid-based electrolytes are not ideal for flexible batteries due to their inherent safety and stability issues. In this study, a non-volatile, non-flammable and safe ionic liquid (IL)-based polymer electrolyte film with solid-like feature is fabricated and incorporated in a flexible lithium ion battery. The ionic liquid is 1-Ethyl-3-methylimidazolium dicyanamide (EMIMDCA) and the polymer is composed of poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP). The electrolyte exhibits good thermal stability (i.e. no weight loss up to 300 °C) and relatively high ionic conductivity (6 × 10−4 S cm−1). The flexible thin-film lithium ion battery based on solid-like electrolyte film is encapsulated using a thermal-lamination process and demonstrates excellent electrochemical performance, in both flat and bent configurations.

Invited Presentation: Lithium Metal Anode: Challenges and Opportunities

Research on lithium metal combined with polymer electrolyte in lithium rechargeable batteries was started in 1979. Since that time, battery research has expanded worldwide. Several new polymers, solid electrolytes and ionic liquids with improved conductivity were identified. These advances resulted from a better understanding of the major parameters controlling ion migration, such as favorable polymer structure, phase diagram between solvating polymer and lithium salt, and the development of new lithium counter-anions. In spite of the progress so far, the quest for a highly conductive dry polymer at room temperature is still not available. However, effort is continuing, and all-lithium polymer battery (LPB) developers presently face the challenge of whether to heat the polymer electrolyte to enable high-power performance, as required for electric vehicle and energy storage. LPB developers have explored both the high-temperature and low-temperature options.This presentation discusses the challenges and opportunities in developing thin lithium metal with stable SEI as negative electrode for three battery technologies using:1. Batteries made from dry polymer and ionic liquid-polymer electrolytes forrechargeable lithium batteries2. All solid-state Li-sulfur batteries 3. Li-air batteries.In addition, we will discuss the safety of lithium, dendrite mechanism, interface phenomena, side reactions, protection of lithium metal, and lithium alloys.

Preparation and characterization of low environmental humidity sensitive ionic liquid polymer electrolytes

ABSTRACTMethyl 3‐(3‐(2‐hydroxyethyl)imidazole‐1‐yl)propanoate chloride salt (IL‐Cl), methyl 3‐(3‐(2‐hydroxyethyl)imidazole‐1‐yl)propanoate bromate salt (IL‐Br), and their derivatives modified by polyethylene glycol (PEG) through ester‐exchange reaction (IL‐PEGs) were synthesized. First, the properties of those materials, especially their conductivity, have been extensively studied. Second, using the IL‐PEG with the highest conductivity as a plasticizer and electrolyte, a series of gel polymer electrolytes were successfully fabricated from polyurethane, poly‐1,4‐butylene adipate glycol 2000, and IL‐PEGs by melting blends with different mass ratios in a Haake torque rheometer. The surface morphology, thermal properties, and the surface resistivity of gel polymer electrolytes were studied by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and surface resistivity test, respectively. Scanning electron microscopy pictures showed that the surface of polymer electrolyte is smoother than that without added IL‐PEGs. Thermogravimetric analysis results revealed that the polymer electrolytes will not decompose when the processing temperature is below 275°C. It was found that the surface resistivity of polymer electrolytes can be below 109 Ω, showing a good antistatic property, and it changes slightly as the relative humidity decreases from 40% to 0.1%, indicting that the material has low humidity sensitivity. This study is a new demonstration and development in ionic liquid based polymer electrolyte. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40675.

Synthesis and ionic conductivity of a novel ionic liquid polymer electrolyte

Hyperbranched poly(glycidol) (HPG) containing hydroxyl groups is firstly synthesized via anionic polymerization, and then reacts with thionyl chloride to form chlorine end-terminated hyperbranched poly(glycidol) (HPG-Cl). Different ionic liquid polymers are synthesized from the reaction of HPG-Cl with N-methylimidazole and then anion exchange with hexafluorophosphoric acid and sodium tetrafluoroborate. The structure and properties of the obtained ionic liquid polymers are characterized by 1H NMR, ATR-FTIR, DSC and TGA, respectively. Ionic conductivity of the polymer electrolytes composed of ionic liquid polymer and lithium bis(trifluoromethanesulfonimide) (LITFSI) is investigated by electrochemical impedance spectroscopy. The results show that the ionic conductivity of the prepared ionic liquid polymer electrolyte can reach 3.5 × 10−4 Scm−1 at 30 °C when the weight ratio of ionic liquid polymer ([HPG-MeIm]BF4) to lithium salt (LiTFSI) is 4.5.

Ionic liquid polymer electrolytes

Ionic liquids (ILs) are room-temperature molten salts that possess unique properties, such as negligible vapour pressure, good thermal stability and non-flammability, together with high ionic conductivity and a wide window of electrochemical stability. Combining ILs with polymer electrolytes offers the prospect of new applications e.g. in batteries and fuel cells, where they surpass the performance of conventional media such as organic solvents (in batteries) or water (in polymer electrolyte membrane fuel cells), giving advantages in terms of improved safety and a higher operating temperature range. However, the most important challenge is how to immobilize ILs in polymer matrices while retaining their sought-after properties. Our goal in this review is to survey the recent developments and issues within IL research in polymer electrolytes.

Characterization and properties of ternary P(VdF-HFP)-LiTFSI-EMITFSI ionic liquid polymer electrolytes

Gel polymer electrolytes containing 1-ethyl-3-methylimidazolium-bis (trifluoromethyl-sulfnyl)imide (EMITFSI) ionic liquid were prepared for lithium ion batteries by solution casting method. Thermal and electrochemical properties have been determined for the gel polymer electrolytes. Proper addition of EMITFSI to the P(VdF-HFP)-LiTFSI polymer electrolyte improves the ionic conductivity and electrochemical window to 2.11 × 10−3 S cm−1 (30 °C) and 4.6 V. In combination of the prepared ternary P(VdF-HFP)-LiTFSI-EMITFSI ionic liquid polymer electrolytes, Li4Ti5O12 anode exhibited two extra voltage plateaus around 1.1 V and 2.3 V except the typical voltage plateau around 1.6 V by possible side reaction between ionic liquid and polymer. LiFePO4 cathode exhibited high capacity above 140 mA h g−1 and retention of 93.1% due to the suppressed polarization effect caused by enhanced ion transport properties. The high temperature of 80 °C didn't have significant impact on the cycling performance.

Ionic liquid–polymer electrolyte for amperometric solid-state NO 2 sensor

A new ionic liquid–polymer electrolyte was successfully tested in the planar amperometric solid-state sensor sensitive towards nitrogen dioxide. The electrolyte consists of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF 6) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) in the ratio 57:43 mol.% and exhibits ionic conductivity 1.6 × 10 −4 S cm −1 at 20 °C, high electrochemical stability (over 4 V on gold or glassy carbon) and thermal stability (over 230 °C). The analyte, gaseous nitrogen dioxide in air, was determined using the electrochemical reduction at −900 mV vs. Pt/air on gold minigrid indicating electrode with Pt/air as a reference electrode. The sensor response is linear in the NO 2 concentration range 0.3–1.1 ppm and is reproducible and long-term stable.

Investigation of PEO-Imidazole Ionic Liquid Oligomer and Polymer Electrolytes for Dye-Sensitized Solar Cells

Ionic liquid oligomer, 1-oligo(ethyleneoxide)-3-methylimidazolium salt (PEO(X)MIm) and Ionic liquid polymer, poly(1-oligo (ethylene glycol) methacrylate-3-methylimidazolium) salt (P(MOEMIm)) prepared by incorporating imidazolium ionic liquid with PEO oligomer and polymer were investigated as electrolytes for dye-sensitized solar cells (DSCs). Ionic liquid electrolytes were composed of LiI, I2, and PEO(X)MImCl or the mixture of 1-hexyl-3-methylidazolium iodide (HMImI), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) and PEO(X)MImCl. Quasi-solid-state electrolytes were prepared by employing the imidazole polymers P(MOEMImCl) to solidify the liquid electrolyte containing lithium iodide, iodine and ethylene carbonate (EC)/propylene carbonate (PC) mixed solvent. Ionic liquid based quasi-solid state electrolytes were prepared by solidifying the ionic liquid electrolytes containing HMImI or a binary mixture of HMImI and EMImBF4 with an ionic liquid polymer P(MOEMImCl), respectively. The influences of PEO molecular weight, polymer content, addition of alkyl ionic liquid and various anions of the ionic liquid oligomers and polymer on the ionic conductivity, apparent diffusion coefficient of the redox species in the electrolytes and the performance of solar cells were examined. The influences on the kinetic behaviors of dye regeneration and triiodide reduction reactions taken place at nanocrystalline TiO2 electrode and Pt counter-electrode, respectively, were also studied by cyclic-voltammetry and electrochemical impedance spectroscopy measurements. By using ternary ionic liquid electrolyte containing 1M lithium iodide and 0.5M iodine in the ionic liquid of the ionic liquid mixture of PEO(X)MImCl), HMImI and EMImBF4, quasi-solid-state electrolytes and ionic liquid based quasi-solid state electrolytes the photoelectron conversion efficiency of DSCs is 7.89%, 7.6% and 6.1%, respectively(AM 1.5, 100mWcm−2). These results show the potential application of PEO based ionic liquid in SCs.

Application of ionic liquid doped solid polymer electrolyte

The electrical, structural, and photoelectrochemical properties of the polymer electrolyte PEO:NaI/I2 doped with an ionic liquid 1-ethyl 3-methylimidazolium dicyanamide (EMImDCN) have been reported. Incorporation of the ionic liquid (IL) increases the membrane homogeneity, decreased surface roughness, and enhances the short current (J sc). Additionally, the doping of IL provides more charge carriers which enhances overall ionic conductivity (σ). The optimized σ was found at 40 wt.% IL composition. The fabricated DSSC using this new solid electrolyte showed 1.43% efficiency at 100 mW cm−2.

Synthesis, characterization and application of biopolymer-ionic liquid composite membranes

Biopolymer composite membranes based on chitosan doped with an ionic liquid (IL) 1-ethyl 3-methylimidazolium thiocyanate (EMImSCN) have been developed and characterized. The doped ionic liquid films show remarkable enhancement in ionic conductivity ( σ). The Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and X-ray diffraction studies (XRD) affirmed the composite nature, good incorporation of ionic liquid and reduction in crystallinity of films, respectively. The interaction between ionic liquid, chitosan and iodide polymer electrolyte matrix was evaluated by cyclic voltammetry. The fabricated dye sensitized solar cell (DSSC) using this new biopolymer electrolyte membranes shows promising performance.