Polypyrrole-Fe2O3 nanohybrid materials for electrochemical storage

We report on the synthesis and electrochemical characterization of nanohybrid polypyrrole (PPy) (PPy/Fe2O3) materials for electrochemical storage applications. We have shown that the incorporation of nanoparticles inside the PPy notably increases the charge storage capability in comparison to the “pure” conducting polymer. Incorporation of large anions, i.e., paratoluenesulfonate, allows a further improvement in the capacity. These charge storage modifications have been attributed to the morphology of the composite in which the particle sizes and the specific surface area are modified with the incorporation of nanoparticles. High capacity and stability have been obtained in PC/NEt4BF4 (at 20 mV/s), i.e., 47 mAh/g, with only a 3% charge loss after one thousand cyles. The kinetics of charge–discharge is also improved by the hybrid nanocomposite morphology modifications, which increase the rate of insertion–expulsion of counter anions in the bulk of the film. A room temperature ionic liquid such as imidazolium trifluoromethanesulfonimide seems to be a promising electrolyte because it further increases the capacity up to 53 mAh/g with a high stability during charge–discharge processes

Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

Conducting polymer nanocomposite-based supercapacitors

The use of nanocomposites of electronically-conducting polymers for supercapacitors has increased significantly over the past years, due to their high capacitances and abilities to withstand many charge-discharge cycles. We have recently been investigating the use of nanocomposites of electronically-conducting polymers containing conducting and non-conducting nanomaterials such as carbon nanotubes and cellulose nanocrystals, for use in supercapacitors. In this contribution, we provide a summary of some of the key issues in this area of research. This discussion includes some history, fundamental concepts, the physical and chemical processes involved, and the challenges that these nanocomposite materials must overcome in order to become technologically viable. Due to space limitations, this is not a complete review of all the work that has been done in this field and we have focused on common themes that appear in the published work. Our aim is that this chapter will help readers to understand the advantages and challenges involved in the use of these materials in supercapacitors and to identify areas for further development

I veicoli elettrici per un trasporto ad alto rendimento energetico e a basso impatto ambientale

Il Piano Energetico Nazionale non pu\uf2 che prevedere per una mobilit\ue0 sostenibile l\u2019introduzione di veicoli elettrici ad alto rendimento energetico e a basso o nullo impatto ambientale. I veicoli elettrici alimentati con batterie convenzionali, in produzione presso le maggiori case automobilistiche, rappresentano gi\ue0 una soluzione per il traffico urbano Italiano, connotato da utenti con percorrenze giornaliere significativamente inferiori ai 100 km alla velocit\ue0 massima di 50 km/h e quindi compatibili con le autonomie delle batterie. I veicoli alimentati con le pi\uf9 avanzate batterie al litio e con celle a combustibile, gi\ue0 sviluppati a livello prototipale, rappresentano, rispettivamente, le soluzioni a medio e a lungo termine per un traffico extraurbano. Nelle sezioni che seguono vengono descritte le problematiche che hanno sino ad oggi ritardato la conversione, anche solo parziale, dell\u2019attuale parco macchine in elettrico e vengono messe in luce le direzioni da perseguire per una fattiva diffusione del veicolo elettrico

Polybithiophene as positive electrode in solid-state polyethylene oxide-LiClO4 lithium rechargeable battery

Cyclability features of an all solid-state lithium polybithiophene battery with PEO20LiClO4 polymer electrolyte was investigated at 70°C working temperature. Although the capacity values of the solid device are lower than those of the comparable one with liquid electrolyte, the cyclability performances are promising and the cycle life is satisfactory. The shelf-life of the solid battery was also investigated. The self-discharge rate is fast at 70°C but is not appreciable at room temperature. © 1990