Polymer electrolyte membranes and process for the production thereof

The process for the production of a polymer electrolyte membrane, comprises the successive steps of: preparing a mixed solution of a Room Temperature Ionic Liquid (RTIL), at least one alkaline metal salt and a photosensitive hydrogen abstracting component at a temperature in the range 20 to 70 °C, wherein the RTIL is a compound consisting of at least one organic cation and at least one organic or inorganic anion; adding to the solution a polymeric material at a temperature in the range of 20-70 °C; blending the solution added with the polymeric material at a temperature in the range of 70-140 °C to get a uniform mixture; pressing the mixture between two sheets at a temperature in the range of 60 - 150 °C and a pressure in the range of 20 - 80 bar, so that a film is formed; and exposing the film to UV light, so that the polymeric material of the film is cross-linked and the polymer electrolyte membrane is obtained

Structure–Performance Correlation of Nanocellulose‐Based Polymer Electrolytes for Efficient Quasi‐solid DSSCs

Nanoscale microfibrillated cellulose (NMFC) was introduced into a light-cured polymeric matrix to result in a green, cheap, and highly efficient quasi-solid electrolyte for the next-generation of bio-based dye-sensitized solar cells. The effect of NMFC on the photovoltaic parameters and performance of the resulting photo-electrochemical cells was thoroughly investigated, and a noticeable increase in both the photocurrent (due to optical phenomena) and the photovoltage (through a shielding effect on the recombination reactions) was demonstrated. Upon thorough optimization of the amount of NMFC introduced into the polymeric network, sunlight conversion efficiencies as high as 7.03 and 8.25 % were achieved at simulated light intensities of 1.0 and 0.4 sun, respectively. Furthermore and outstandingly, the addition of NMFC positively affected the long-term stability of the device, which was able to retain >95 % of its initial efficiency after 500 h of extreme aging condition

Contrast Enhancement in Polymeric Electrochromic Devices Encompassing Room Temperatu re Ionic Liquids

We report the preparation and spectro - electrochemical characterization of electrochromic devices (ECD) combining inkjet - printed WO 3 as cathode and electro - deposited V 2 O 5 as anode. ECD were prepared for the first time with an optimized formulation of gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) encompassing the Room Temperature Ionic Liquid (RTIL, 1 - Ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide) as solvent. The UV - VIS spectrum of ECD was recorded at different potentials during Li + insertion and de - insertion; additionally the Percent Trasmittance (T%) of ECD vs. time was investigated during repeated bleaching and coloring cycles allowing thus the esti mation of switching times and device stability. Due to the lower ionic conductivity and the apparent superior solvent permeability within WO 3 active layer, RTIL containing ECD showed slower switching times, but higher contrast with respect to the similar o nes with EC/DEC as solvent. These results indicate that the ECD containing environment - friendly RTIL electrolytes are suitable for applications requiring high contrast, high safety and moderately fast switching times

Materials for electrochemical energy conversion and storage: novel approaches and chemistry thereof

Energy has become one of the predominant scientific research areas in the 21st century. Fossil fuels can no longer represent the predominant energy supply for human being. Their use must be reduced and alternative sustainable energy resources have to be identified and rapidly exploited. Besides conversion technologies, also the energy storage must be considered. Electrochemical systems, such as batteries and supercapacitors that can efficiently store and deliver energy on demand in stand-alone power plants, as well as provide power quality and load leveling of the electrical grid in integrated systems, are playing a crucial role in this respect. Annual worldwide research efforts in the field of energy conversion and storage are immense, and more than 10,000 publications per year are indexed by ISI. At the same time, some of these technologies are implemented on a large scale, thus turning out that the materials traditionally used are often critical in terms of safety, cost and environmental impact. In this contribution, two of the most important energy technologies are thoroughly discussed: third-generation solar cells and secondary Li-/Na-ion batteries. Newly elaborated approaches on the selection, functionalization and investigation of materials are presented, also highlighting their key points with respect to those reported in the literature so far. The present communication is intended to show a brief overview of the promising prospects of abundant and readily available raw materials specifically selected and developed for energy storage and conversion devices. In particular, the use of water, (bio-)polymers and light-induced functionalization techniques are demonstrated to allow performance, stability and up-scalable feature previously unpredictable on the basis of traditional chemical and physical approaches. The research trends and future prospects are also discussed

Materials for electrochemical energy conversion and storage: novel approaches and chemistry thereof

Energy has become one of the predominant scientific research areas in the 21st century. Fossil fuels can no longer represent the predominant energy supply for human being. Their use must be reduced and alternative sustainable energy resources have to be identified and rapidly exploited. Besides conversion technologies, also the energy storage must be considered. Electrochemical systems, such as batteries and supercapacitors that can efficiently store and deliver energy on demand in stand-alone power plants, as well as provide power quality and load leveling of the electrical grid in integrated systems, are playing a crucial role in this respect. Annual worldwide research efforts in the field of energy conversion and storage are immense, and more than 10,000 publications per year are indexed by ISI. At the same time, some of these technologies are implemented on a large scale, thus turning out that the materials traditionally used are often critical in terms of safety, cost and environmental impact. In this contribution, two of the most important energy technologies are thoroughly discussed: third-generation solar cells and secondary Li-/Na-ion batteries. Newly elaborated approaches on the selection, functionalization and investigation of materials are presented, also highlighting their key points with respect to those reported in the literature so far. The present communication is intended to show a brief overview of the promising prospects of abundant and readily available raw materials specifically selected and developed for energy storage and conversion devices. In particular, the use of water, (bio-)polymers and light-induced functionalization techniques are demonstrated to allow performance, stability and up-scalable feature previously unpredictable on the basis of traditional chemical and physical approaches. The research trends and future prospects are also discusse

Development of multipurpose ethylene oxide based polymer electrolytes for smart and energy efficient devices

Wide interest is mounting on polymer electrolytes for application in energy efficient devices such as rechargeable batteries, electrochromics and photovoltaics. Solid polymer electrolytes exhibit unique advantages: mechanical integrity, variety of fabrication methods and intimate electrode/electrolyte interfacial properties. They also improve safety along with more compact and lightweight packaging. Since the discovery of ionic conductivity in alkali metal salt complexes of poly(ethylene oxide), PEO, lot of research was devoted on systems containing lithium salts to be used as electrolytes, particularly in Li-based batteries. In this work, highly ionic conducting PEO-based polymer electrolytes, encompassing lithium salts dissolved in Room Temperature Ionic liquids (RTIL), were successfully prepared via rapid hot-press and subsequently cross-linked via UV irradiation. All the prepared materials were thoroughly characterised in terms of their physical, chemical and morphological properties and tested for ionic conductivity, electrochemical stability and cycling performances. The UV-curing process on such materials led to the production of elastic and resistant polymer electrolyte membranes. The degree of PEO crystallinity was greatly reduced down to the amorphous state by addition of lithium salt and RTIL and UV-induced cross-linking process. As a consequence, a noticeably increased ionic conductivity was registered (> 10-4 Scm-1 at RT). The polymer electrolyte demonstrated a very stable interfacial stability versus lithium metal and a very wide electrochemical stability window (0-5.5 V vs. Li). In the presence of such an electrolyte, the laboratory-scale devices showed remarkable performances, only slightly lower than those using liquid electrolyte, respect to which demonstrated a much greater durability. The obtained findings demonstrate that our proposed preparation can provide a new, easy and low cost approach to fabricate polymer electrolytes with remarkable performance for the next generation of advanced flexible energy production and storage device

Does Cell Polarization Matter in Single-Ion Conducting Electrolytes?

Single-ion conducting polymer electrolytes (SIPE) are particularly promising electrolyte materials in lithium metal-based batteries since theoretical considerations suggest that the immobilization of anions avoids polarization phenomena at electrode|electrolyte interfaces. SIPE in principle could allow for fast charging while preventing cell failure induced by short circuits arising from the growth of inhomogeneous Li depositions provided that SIPE membranes possess sufficient mechanical stability. To date, different chemical structures are developed for SIPE, where new compounds are often reported through electrochemical characterization at low current rates. Experimental counterparts to model-based assumptions and determination of system limitations by correlating both models and experiments are rare in the literature. Herein, Chazalviel’s model, which is derived from ion concentration gradients, is applied to theoretically determine the limiting current density (JLim) of a SIPE. Comparison with the experimentally obtained JLim reveals a large deviation between the theoretical and practical values. Beyond that, charge–discharge profiles show a distinct arcing behavior at moderate current densities (0.5 to 1 mA cm–2), indicating polarization of the cell, which is not so far reported for SIPE. In this context, by application of various electrochemical and physiochemical methods, the details of cell polarization and the role of the solid electrolyte interphase in producing arcing behavior in the voltage profiles in stripping/plating experiments are revealed, which eventually also elucidate the inconsistency of JLim

Super Soft All-Ethylene Oxide Polymer Electrolyte for Safe All-Solid Lithium Batteries

Here we demonstrate that by regulating the mobility of classic −EO− based backbones, an innovative polymer electrolyte system can be architectured. This polymer electrolyte allows the construction of all solid lithium-based polymer cells having outstanding cycling behaviour in terms of rate capability and stability over a wide range of operating temperatures. Polymer electrolytes are obtained by UV-induced (co)polymerization, which promotes an effective interlinking between the polyethylene oxide (PEO) chains plasticized by tetraglyme at various lithium salt concentrations. The polymer networks exhibit sterling mechanical robustness, high flexibility, homogeneous and highly amorphous characteristics. Ambient temperature ionic conductivity values exceeding 0.1 mS cm−1 are obtained, along with a wide electrochemical stability window (>5 V vs. Li/Li+), excellent lithium ion transference number (>0.6) as well as interfacial stability. Moreover, the efficacious resistance to lithium dendrite nucleation and growth postulates the implementation of these polymer electrolytes in next generation of all-solid Li-metal batteries working at ambient condition

Mechanistically Novel Frontal‐Inspired in situ Photopolymerization: An Efficient Electrode|Electrolyte Interface Engineering Method for High Energy Lithium Metal Polymer Batteries

The solvent-free in situ polymerization technique has the potential to tailor-make conformal interfaces that are essential for developing durable and safe lithium metal polymer batteries (LMPBs). Hence, much attention has been given to the eco-friendly and rapid ultraviolet (UV)-induced in situ photopolymerization process to prepare solid-state polymer electrolytes. In this respect, an innovative method is proposed here to overcome the challenges of UV-induced photopolymerization (UV-curing) in the zones where UV-light cannot penetrate, especially in LMPBs where thick electrodes are used. The proposed frontal-inspired photopolymerization (FIPP) process is a diverged frontal-based technique that uses two classes (dual) of initiators to improve the slow reaction kinetics of allyl-based monomers/oligomers by at least 50% compared with the conventional UV-curing process. The possible reaction mechanism occurring in FIPP is demonstrated using density functional theory calculations and spectroscopic investigations. Indeed, the initiation mechanism identified for the FIPP relies on a photochemical pathway rather than an exothermic propagating front forms during the UV-irradiation step as the case with the classical frontal photopolymerization technique. Besides, the FIPP-based in situ cell fabrication using dual initiators is advantageous over both the sandwich cell assembly and conventional in situ photopolymerization in overcoming the limitations of mass transport and active material utilization in high energy and high power LMPBs that use thick electrodes. Furthermore, the LMPB cells fabricated using the in situ-FIPP process with high mass loading LiFePO4 electrodes (5.2 mg cm-2) demonstrate higher rate capability, and a 50% increase in specific capacity against a sandwich cell encouraging the use of this innovative process in large-scale solid-state battery production

Newly Elaborated Multipurpose Polymer Electrolyte Encompassing RTILs for Smart Energy-Efficient Devices

Profoundly ion-conducting, self-standing, and tack-free ethylene oxide-based polymer electrolytes encompassing a room-temperature ionic liquid (RTIL) with specific amounts of lithium salt are successfully prepared via a rapid and easily upscalable process including a UV irradiation step. All prepared materials are thoroughly characterized in terms of their physical, chemical, and morphological properties and eventually galvanostatically cycled in lab-scale lithium batteries (LIBs) exploiting a novel direct polymerization procedure to get intimate electrode/electrolyte interfacial characteristics. The promising multipurpose characteristics of the newly elaborated materials are demonstrated by testing them in dye-sensitized solar cells (DSSCs), where the introduction of the iodine/iodide-based redox mediator in the polymer matrix assured the functioning of a lab-scale test cell with conversion efficiency exceeding 6% at 1 sun. The reported results enlighten the promising prospects of the material to be successfully implemented as stable, durable, and efficient electrolyte in next-generation energy conversion and storage devices