A novel flame retardant and film-forming electrolyte additive for lithium ion batteries

Allyl tris(2,2,2-trifluoroethyl) carbonate (ATFEC) was synthesized as a bi-functional additive of flame retardant and film former in electrolytes for lithium ion batteries (LIBs). The flame retardancy of the additive was characterized with differential scanning calorimetry (DSC) and self-extinguishing time (SET). It is shown that adding 1 vol.% ATFEC in 1 M LiPF₆/propylene carbonate (PC) can effectively enhance the thermal stability of the electrolyte and suppress the co-intercalation of PC into the graphitic anode. Further evaluation indicates that the additive hardly affect the conductivity of electrolyte. These support the feasibility of using ATFEC as an additive on formulating an electrolyte with multiple functions such as film-forming enhancement, high thermal stability and high ionic conductivity.     

Printed, flexible electrochromic displays using interdigitated electrodes

We describe herein some of our initial studies in pursuit of a simple, economical method of mass producing electrochromic displays. The approach we have taken is to print the display on polymer film utilizing commercially available conductive inks in an interdigitated electrode structure with a conductive metal oxide powder, dispersed in a polymer binder, as the electrode surface. A range of electrochromic materials suitable for use with an aqueous gel electrolyte have been explored and examples presented.     

Application of sulfonium-, thiophenium-, and thioxonium-based salts as electric double-layer capacitor electrolytes

The purpose of this paper is to develop novel molten salts based on sulfonium, thiophenium, and thioxonium cations as electrolytes for EDLCs. We evaluated various kinds of the salts, with tetrafluoroborate (BF₄) and bis(trifluorometanesulfonyl)amide (TFSA) anions, including several kinds of ionic liquids. The cell using the electrolyte containing diethylmethylsulfonium (DEMS)-BF₄ salt had the higher capacitance and the lower DC-IR value than those containing conventional salts such as 1-ethyl-3-methylimidazolium (EMI)-BF₄ and N,N,N-triethyl-N-methylammonium (TEMA)-BF₄ at 243 K and 2 V. The capacitance and DC-IR at low temperature depended strongly on the structure, particularly on the size of each ion. We also examined the durability of cells by continuous charging at 333 K and 2.5 V. The stabilities of sulfonium-, thiophenium-, and thioxonium-based electrolytes were much inferior to that of EMI-BF₄.     

Ionic conductivity of apatite-type solid electrolyte material, La10−XBaXSi6O27−X/2 (X = 0-1), and its fuel cell performance

We prepared Ba substituted lanthanum silicate (La_10−XBa_XSi₆O_27−X/2) and examined the effect of Ba substitution on the crystal structure and conductivity. The X-ray diffraction (XRD) results for a series of compositions showed that Ba ion can occupy the La site of an apatite structure with the composition La_10−XBa_XSi₆O_27−X/2 (X = 0-1). Rietveld analysis of the synchrotron XRD profiles revealed Ba occupation in the La 4f site rather than the La 6 h site and a decrease in the occupation factors of the oxide ions of the SiO₄ tetrahedra.The conductivity of La_10−XBa_XSi₆O_27−X/2 exhibited a maximum at X = 0.6 and the value was the same as that of YSZ (8 mol% Y₂O₃ doped ZrO₂) at 750 °C. On the other hand, the activation energy of about 50 kJ mol⁻¹ for La_9.4Ba_0.6Si₆O_26.7 was smaller than that of YSZ. Thus the conductivity of La_9.4Ba_0.6Si₆O_26.7 was a higher than those of YSZ below 750 °C. The conductivity parallel to the c-axis which is attributed to the 2a site oxide ions migration is known to be dominant in La₁₀Si₆O₂₇. However, Ba substitution seems to produce oxygen vacancies and create another pathway for oxide ions perpendicular to the c-axis. The increase in the pathways leads to an increase in the conductivity. We also reported the solid oxide fuel cell (SOFC) performance of La_10−XBa_XSi₆O_27−X/2 with a maximum power density of 65 mW cm⁻² using La_0.9Sr_0.1CoO_3−δ as a cathode and NiO-SDC (Sm doped CeO₂) as an anode.     

Performance of carbon-carbon supercapacitors based on organic, aqueous and ionic liquid electrolytes

Properties of capacitors working with the same carbon electrodes (activated carbon cloth) and three types of electrolytes: aqueous, organic and ionic liquids were compared. Capacitors filled with ionic liquids worked at a potential difference of 3.5 V, their solutions in AN and PC were charged up to the potential difference of 3 V, classical organic systems to 2.5 V and aqueous to 1 V. Cyclic voltammetry, galvanostatic charging/discharging and impedance spectroscopy were used to characterize these capacitors. The highest specific energy was recorded for the device working with ionic liquids, while the highest power is characteristic for the device filled with aqueous H₂SO₄ electrolyte. Aqueous electrolytes led to energy density an order of magnitude lower in comparison to that characteristic of ionic liquids.     

Electrolyte effect on the catalytic performance of Ni-based catalysts for direct internal reforming molten carbonate fuel cell

An active and tolerant Ni-based catalyst for methane steam reforming in direct internal reforming molten carbonate fuel cells (DIR-MCFCs) was developed. Deactivation of reforming catalysts by alkali metals from the electrolyte composed of Li₂CO₃ and K₂CO₃ is one of the major obstacles to be overcome in commercialization of DIR-MCFCs. Newly developed Ni/MgSiO₃ and Ni/Mg₂SiO₄ reforming catalysts show activities of ca. 80% methane conversion. Subsequent to electrolyte addition to the catalyst, however, the activity of Ni/Mg₂SiO₄ decreases to ca. 50% of its initial value, whereas Ni/MgSiO₃ catalyst retains its initial activity. Results obtained from temperature-programmed reduction and X-ray photoelectron spectroscopy identify unreduced Ni³⁺ as a decisive factor in keeping catalytic activity from the electrolyte.     

Ion-based SAFT2 to represent aqueous multiple-salt solutions at ambient and elevated temperatures and pressures

Ion-based SAFT2 is extended to the properties of aqueous multiple-salt solutions at ambient and elevated temperatures and pressures. The short-range interactions between two different cations are allowed to obtain better representations of the solution properties. The adjustable parameter used in the mixing rule for the segment energy is fitted to the experimental osmotic coefficients of two-salt solutions containing one common anion at various temperatures and low pressures. The predictions of the osmotic coefficients, densities, and activity coefficients of multiple-salt solutions including brine/seawater are found to agree with experimental data.     

Ionic liquid electrolytes based on 1-vinyl-3-alkylimidazolium iodides for dye-sensitized solar cells

Five new ionic liquids of 1-vinyl-3-alkylimidazolium iodide were synthesized to develop novel electrolytes for dye-sensitized solar cells. The effects of photovoltaic characteristics of the cell and the ionic liquid features such as viscosity and ionic conductivity were described. The 1-vinyl-3-alkylimidazolium cation volume was calculated by quantum chemistry method. The linear dependence of photon-to-current conversion efficiency on the non-solvated cation volume was revealed. After lithium iodide was added to 1-vinyl-3-alkylimidazolium salts as electrolytes, except the photovoltage, the photocurrent, fill factor and photon-to-current efficiency were improved correspondingly.     

Changes in fatty acid composition and electrolyte leakage of ‘Hayward’ kiwifruit during storage at different temperatures

Exposure to low storage temperature induces changes in electrolyte leakage and fatty acids composition, in a way depending on the plant tissue. Those changes alter the response of the fruit to storage conditions. The influence of storage temperature on ripening, fatty acids composition and electrolyte leakage of ‘Hayward’ kiwifruit were investigated. Harvested fruit were stored at 0, 5, 10, 15 and 20 °C for 5, 12 and 17 days. Measurements of SSC, firmness, flesh colour, fatty acid composition and electrolyte leakage were performed during the experiment. Kiwifruit did not fully ripen during the 17 days storage at any temperature. The major fatty acid component in ‘Hayward’ kiwifruit consisted of linolenic, followed by oleic, palmitic, linoleic and stearic acid. Membrane permeability and unsaturated/saturated fatty acid ratio increased during storage in all treatments. The highest increase was during the first 5 days and at the lowest temperatures. The increase in unsaturated/saturated fatty acid ratio was caused mainly by a decrease in palmitic and an increase in oleic acids. Stearic, linoleic and linolenic acids had insignificant changes during storage. The main increase in electrolyte leakage and unsaturated/saturated fatty acid ratio occurred during the first storage days and at lower temperatures, probably as a response of the tissue to an adaptation to the new stress storage conditions.