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Abstract: This paper examines the behaviour of lithium polymer electrolytes based on aromatic sulfonamide salts tailored to optimize negative charge delocalization through the aromatic ring and up to the nitro substituents located in the para and para/ortho positions of the nitrogen of the sulfonamide anion. For the first time, lithium salt dissociation has been connected to the Σ + value. Thanks to the tailoring of these anions and to this physico-chemical approach it has been possible to show that resonance electron-withdrawing effects, as opposed to inductive ones, are decisive in reaching high conductivities in aprotic polymer electrolytes. Moreover the dissociation enhancement that can be expected, using the Σ + value of NO2, from the introduction of an additional nitro group, is in good agreement with the conductivity enhancement. [Copyright &y& Elsevier]

Abstract: Nanocomposite polymer electrolytes composed of high molecular weight poly(oxyethylene) PEO as a matrix, LiTFSI as lithium salt and ramie, cotton and sisal whiskers with high aspect ratio and sisal microfibrils (MF), as reinforcing phase were prepared by casting-evaporation. The morphology of the composite electrolytes was investigated by scanning electron microscopy and their thermal behavior (characteristic temperatures, degradation temperature) were investigated by thermogravimetric analysis and differential scanning calorimetry. Nanocomposite electrolytes based on PEO reinforced by whiskers and MF sisal exhibited very high mechanical performance with a storage modulus of 160MPa at high temperature. A weak decrease of the ionic conductivity was observed with the incorporation of 6wt% of whiskers. The addition of microfibrils involved a larger decrease of the conductivity. This difference may be associated to the more restricted PEO mobility due to the addition of entangled nanofibers. [Copyright &y& Elsevier]

Graphical abstract Highlights • Highly conductive polysiloxanes based electrolytes with different viscosities were studied in DSSCs. • Bimodal TiO 2 showed better pore infiltration and light harvesting while maintaining a high surface area. • Lower charge transfer resistance was obtained for the bimodal TiO 2. • Efficient and stable quasi-solid-state DSSCs are achieved. Abstract In this article, we discuss the effect of the polysiloxane-based poly(ionic liquid) (PIL) electrolytes viscosity on the infiltration into mesoporous and bimodal TiO 2 thin films with different thickness, and consequently on the DSSC performance. The mesoporous films contain small mesopores of 8–10 nm, resulted from the use of Pluronic P123 surfactant (SOFT), resulting in high surface area. The DUAL (soft/hard) templated films have unique bimodal porous structures comprising 8–10 nm mesopores and 60–70 nm macropores resulted from the use of P123 and 130 nm polystyrene beads, which encouraged the electrolyte pore infiltration and light harvesting. Electrochemical impedance spectroscopy confirms the lower charge transfer resistance of the DUAL templated TiO 2 films as opposed to SOFT TiO 2 electrodes which corresponds to higher DSSC efficiency, despite having lower dye adsorption thanks to the improved PIL electrolyte infiltration within larger pores. The addition of ionic liquids to PIL significantly lowers the viscosity, increases the ionic conductivity and I 3 − diffusion rate, resulting in noticeable improvement in photovoltaic performance in both SOFT and DUAL templated photoanodes for all the observed thickness. [ABSTRACT FROM AUTHOR]

Abstract This article describes a cell architecture that achieves enhanced light harvesting with less dye quantity while simultaneously improving the performance of the polysiloxane-based solid-state dye-sensitized solar cells (DSSCs). We report the synthesis of bimodal mesoporous anatase TiO 2 films by a dual templating approach, combining a block-copolymer template (Pluronic P123) and polystyrene nanospheres (PS) as soft and hard templates, respectively. The AFM and TEM analysis of TiO 2 films revealed a mixture of mesoporous and macroporous morphology in which dual porosity is generated by combustion of soft and hard templates. The size of the macropores was varied by employing PS beads with different diameters (62, 130 and 250 nm). The influence of the macropore size on the dye loading and pore infiltration is the main purpose of this article. The bimodal porosity leads to increased light scattering due to enhanced optical path length, and better pore infiltration of the polysiloxane electrolyte is achieved. The amount of dye uptake by the dual films is lower than that of soft films because the large pore size reduces the total surface area. The optimum bimodal structure was obtained when combining P123 surfactant and the 130 nm PS beads leading to the lowest charge transfer resistance and a high efficiency for DSSCs is reported with both liquid and polymer electrolytes. Even if the dye uptake was lower, the photovoltaic performance has been maintained and improved in some devices. The open circuit voltage and fill factor were improved, owing to a successful joining of different effects i.e. increased light harvesting, facile electrolyte penetration and reduced charge recombination. Graphical abstract Image 1 Highlights • New bimodal TiO 2 layers with controlled porosity were prepared by soft and hard templating. • TiO 2 bimodal layers were first time tested in DSSCs comprising viscous polysiloxane electrolyte. • TiO 2 with optimized DUAL porosity showed better pore infiltration and light harvesting while maintaining a high surface area. • The optimized DUAL structure showed the lowest charge transfer resistance. • Best performance in DSSCs was obtained for the bimodal TiO 2 layer comprising 8–10 mesopores and 60–80 nm macropores. [ABSTRACT FROM AUTHOR]

Abstract: Nanocomposite polymer electrolytes based on a plasticized high molecular weight poly(oxyethylene) (POE) reinforced with high aspect ratio cellulose nanoparticles were reported. The influence of tetra(ethylene) glycol dimethyl ether (TEGDME) as plasticizer is investigated. The study mainly focuses on the dynamic mechanical behavior and ionic conductivity performances. The miscibility of the blend POE/TEGDME was investigated using both thermal and mechanical investigations. Viable polymer electrolytes can be obtained from this combination, conciliating acceptable ionic conductivities and outstanding mechanical performances on a large temperature range. [Copyright &y& Elsevier]

• PBQDS was prepared as a novel positive electrode material for magnesium and lithium batteries. • The PBQDS based cathode delivered a high capacity of 140 mAh/g at C/20 for Li cell. • In Mg cell, the capacity decrease is related to Mg2+ trapping inside the cathode material due to O/Mg2+ interaction. • High solvating additive could mitigate the trapping process. The study of innovative solutions to replace current lithium technology is being carried out at a rapid pace. One of the proposed solution is the development of magnesium batteries, especially organic positive electrode which can exhibit high capacity and capacity retention. In this field, the electrochemical responses of poly(benzoquinonyldisulfide) (PBQDS) in lithium and magnesium cells were investigated in diglyme and sulfolane based electrolytes. Using cavity micro-electrode, similar response was obtained by cyclic voltammetry with the presence of a reversible redox system at 3.5 V vs. Li+/Li or 2.2 V vs. Mg2+/Mg. Using sulfolane + LiTFSI (bis(trifluoromethane)sulfonamide lithium salt) electrolyte, the PBQDS active material achieves a stable capacity of 140 mAh g−1 at C/20. In Mg cell, even if the starting capacity is high, a capacity decrease is noticed along time presumably due to the progressive Mg2+ trapping within the quinone structure. The addition of solvating additive permits to partially mitigate this drawback. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing flexible solid-state micro-supercapacitors with large potential window is crucial for many technologies. The present study focuses on the synthesis and elaboration of quasi-solid-state (QSS) electrolytes with an electrochemical stability greater than 3.0 V based on functionalized polysiloxane. Their electrochemical behavior was studied with silicon nanowires electrodes. The polysiloxane was functionalized with both ammonium and cross-linkable functions. The nanostructured electrodes were impregnated with a mixture of ionic liquid and functionalized polysiloxane. The crosslinking of the polymer electrolyte was then performed by thermal curing directly within the nanostructured electrodes. The quasi-solid system exhibits very high stability upon galvanostatic cycling i.e. during 100 000 cycles with a cell potential of 3.0 V only a capacitance loss of 2.10−5% per cycle was registered. The performance of this QSS with safe electrolyte is remarkable. [Display omitted] [ABSTRACT FROM AUTHOR]

Combining polycondensation/hydrogenation allowed varying crosslink density in a controlled way. The obtained solvent-free and oligomer-free polymer electrolytes exhibit outstanding conductivities in a wide temperature range. In comparison with poly(oxyethylene) (PEO) based electrolytes, the conductivities of the new crosslinked polymer electrolytes are much higher at ambient temperatures. Furthermore, their conductivity maxima exceed the PEO ones and, to the best of our knowledge, are the highest known. Moreover, contrary to PEO electrolytes, they don’t creep after melting. The unsophisticated architecture and chemistry make easy the scale up of these promising polymer electrolytes. [ABSTRACT FROM AUTHOR]

[Display omitted] • I 2 -free polysiloxane electrolytes are prepared for efficient solid-state DSSCs. • Raman spectroscopy confirms the in-situ tri-iodide generation in DSSCs. • The champion DSSC achieves 8.3% under 1 sun and retains 84% of its initial value after 26 months. • I 2 -free electrolyte brings the semi-transparent character to the DSSCs. • Reduced charge recombination and enhanced electron lifetime have been obtained for I 2 -free DSSCs. Achieving highly stable and efficient dye-sensitized solar cells (DSSCs) remains a major challenge for future industrial development. In the present work, a series of ionic conductors, such as ionic liquids (ILs), polysiloxane-based poly(ionic liquid)s (PILs), and their blends are employed as electrolytes in quasi-solid-state DSSCs. In particular, we study the effect of PILs ionic functionality interaction with the ILs and ethylene carbonate (EC) on the photovoltaic performance of DSSCs with and without iodine (I 2). Omitting I 2 from the electrolytes in fabricated DSSCs enhances both V oc and J sc due to the reduced charge recombination and extended effective electron lifetime. We confirm through Raman spectroscopy that in I 2 -free DSSCs, the in-situ generated tri-iodides (I 3 −) ions are sufficient enough to complete the reaction mechanism. Additionally, the I 2 -free DSSCs exhibit enhanced transparency, encouraging our efforts towards BIPV suitable applications. When plasticized with EC, the ionic conductivities of the highly functionalized I 2 -free PIL-based DSSCs exceeds 10−3 S cm−1 at 30 °C, giving record PCE of 8.3% and 9.1% under standard (1 sun) and modest (0.3 sun) illumination, respectively. These devices also show excellent long-term stability, retaining about 84% of their initial efficiency after 26 months. [ABSTRACT FROM AUTHOR]