A New (Trifluoromethane)Sulfonylimide Single-Ion Conductor with PEG Spacer for All-Solid-State Lithium-Based Batteries

The choice of ionic-liquid-like monomers (ILM) for single-ion conducting polyelectrolytes (SICPs) is crucial for the performance of all solid-state lithium batteries. In the current study, we propose a novel approach for development of SICPs via design and synthesis of a new ILM with long poly(ethylene oxide) spacer between methacrylic group and (trifluoromethane)sulfonylimide anion. Its homopolymer shows an ionic conductivity that is ∼5 orders of magnitude higher (9.2 × 10−8 S cm−1 at 25 °C), in comparison with previously reported analogues, while the conductivity of its random copolymer with poly(ethylene glycol)methylethermethacrylate reaches the levels of 10−6 and 10−5 S cm−1 at 25 and 70 °C, respectively. The copolymer provides excellent thermal (Tonset ≈ 200 °C) and electrochemical (4.5 V vs Li+/Li) stabilities, good compatibility with Li metal, and effective suppression of dendrite growth. Li/SICP/LiFePO4 cells are capable of reversibly operating at different C rates, demonstrating excellent Coulombic efficiency and retaining specific capacity upon prolonged charge/discharge cycling at a relatively high current rate (C/5) at 70 °C

Design of ionic liquid like monomers towards easy-accessible single-ion conducting polymer electrolytes

The rational design of single-ion polymer electrolytes emerges as a primary strategy for enhancing the performance of lithium ion batteries. With the aim to increase ionic conductivity, four novel ionic liquid monomers were designed and synthesized in high purity. Such monomers differ from the previously reported systems by (1) the presence of a long and flexible spacer between the methacrylate group and chemically bonded anion or (2) by a long perfluorinated side chain. The investigation of their free radical copolymerization with poly(ethylene glycol) methyl ether methacrylate (PEGM) allowed to identify the impact of thei copolymer composition on thermal and ion conducting properties. The copolymer based on lithium 3-[4-(2-(methacryloyloxy)ethoxy)-4-oxobutanoyl)oxy) propylsulfonyl]-1-(trifluoromethylsulfonyl)imide showed the highest ionic conductivity (1.9 × 10−6 and 2 × 10−5 S cm−1 at 25 and 70 °C, respectively) at [EO]/[Li] = 61 ratio, along with a wide electrochemical stability (4.2 V vs. Li+/Li) and high lithium-ion transference number (0.91). The prepared copoly(ionic liquid)s (coPILs) were further applied for the assembly of Li/coPIL/LiFePO4 lithium-metal cells, which were capable to reversibly operate at 70 °C delivering relatively high specific capacity (up to 115 mAh g−1) at medium C/15 current rate

Conductive films based on composite polymers containing ionic liquids absorbed on crosslinked polymeric ionic-like liquids (SILLPs)

Polymerization of styrenic monomers containing imidazolium subunits in the presence of crosslinking monomers and using ionic liquids (ILs) as porogenic agents provides composite materials with excellent mechanical properties and displaying conductivities that are in the same order of magnitude than those shown by bulk ILs. This approach allows the use of high crosslinking degrees and low IL-loadings without compromising the required properties of the resulting composites. Besides, no appreciable leaching of the bulk IL component is detected.Financial support by Ministerio de Ciencia e Innovacion (CTQ2011-28903-C02-01 and SP-ENE-20120718), Generalitat Valenciana (PROMETEO/2012/020) and Universitat Jaume I (P11B2013-38) is acknowledged.Altava Benito, B.; Compañ Moreno, V.; Andrio Balado, A.; Del Castillo Davila, LF.; Mollá Romano, S.; Burguete, MI.; García-Verdugo Cepeda, E.... (2015). Conductive films based on composite polymers containing ionic liquids absorbed on crosslinked polymeric ionic-like liquids (SILLPs). Polymer. 72:69-81. https://doi.org/10.1016/j.polymer.2015.07.009S69817

Polymerization of the new double-charged monomer bis-1,3(N,N,N trimethylammonium dicyanamide)-2-propylmethacrylate and ionic conductivity of the novel polyelectrolytes

The achievement of high ionic conductivity in single-ion conducting polymer electrolytes is one of the important aims for various electrochemical devices including modern lithium batteries. One way to enhance the ionic conductivity in polyelectrolyte systems is to increase the quantity of charge carriers in each monomer unit. Highly charged poly(bis-1,3(N,N,N-trimethylammonium)-2-propylmethacrylate) with one of the most conducting anions, namely dicyanamide, was prepared via free radical bulk polymerization or using ionic liquids as reaction medium. The cationic polymers of the double-charged monomer have molar masses up to equation image = 1,830,000 g/mol and the ionic conductivity equal to 5.51 × 10−5 S/cm at 25°C. The film forming ability, crystallinity, thermal stability, and glass transition temperatures of the new polymeric ionic liquids obtained from detailed studies are presente

Progress in the use of ionic liquids as electrolyte membranes in fuel cells

This work provides a critical review of the progress in the use of Room Temperature Ionic Liquids (RTILs) as Proton Exchange Membrane (PEM) electrolytes in Fuel Cells (FCs). It is well-known that for an efficient early commercialisation of this technology it is necessary to develop a proton exchange membrane with high proton conductivity without water dependency capable of working at temperatures above 100 °C. The use of ionic liquids as electrolytes in electrochemical devices is an emerging field due to their high conductivity, as well as their thermal, chemical and electrochemical stability under anhydrous conditions. This paper attempts to give a general overview of the state-of-the-art, identifies the key factors for future research and summarises the recent progress in the use of ionic liquids as an innovative type of PEMs.This research was supported by the Ministry of Education, Culture and Sport under the Project CTQ2012-31639 (MINECO, SPAIN-FEDER2001–2013)