Non-aqueous electrolytes are stable over wide electrochemical potential windows, generally >2 V, and therefore hold promise for enabling higher energy and power density redox flow batteries (RFBs). Nevertheless, the development of non-aqueous RFBs is at an early stage and significant research efforts are needed to demonstrate non-aqueous RFBs with performance characteristics that exceed those of aqueous RFBs. The membrane or separator is a critical component that to a great extent determines the performance of RFB systems for practical applications. In this work, the performance of a RFB was evaluated with Nafion 1035 membranes and Daramic 175 SLI microporous separators. The non-aqueous electrolyte was based on vanadium (III) acetylacetonate. This chemistry possesses two couples over ∼2.2 V. Charge-discharge cycles were performed in a RFB at a current density of 10 mA cm −2 . Coulombic and energy efficiencies of 91% and 80% were achieved using the Nafion membrane. A similar RFB using the Daramic microporous separator achieved columbic and energy efficiencies of 73% and 68%, respectively. The source of capacity decay during multiple charge-discharge cycles was also investigated. The loss in the capacity was related to the poor chemical stability of the vanadium acetylacetonate in the positive electrolyte during battery cycling. Redox flow batteries (RFBs) have emerged as very attractive options for large-scale energy storage applications and, could facilitate the integration of renewable energy resources (e.g. wind and solar) with the current electricity grid.1,2 RFBs are electrochemical devices that store electrical energy in soluble electro-active species in a liquid electrolyte. The electro-active species are stored externally in separate reservoirs and are pumped through the battery stack during operation. The energy is stored or delivered by means of a redox reaction between the two species with different standard electrode potentials, separated by a membrane.2,3 Unlike conventional batteries, RFBs are more attractive for large scale energy storage because they offer more flexible operation, simple electrode reactions, longer cycle life, higher overall energy efficiencies and easier scale-up. 4 Nonetheless, RFB technology is still in an early stage; challenges that remain in the quest to produce devices with high power and energy density at low cost include the discovery or development of stable, high energy density redox electrolytes, and efficient and low cost membranes or separators. 1,5 Aqueous and non-aqueous chemistries are being investigated for use in RFBs. The cell potential of aqueous RFBs is limited to less than ∼1.6 V primarily due to the electrochemical stability of water at carbon/graphite electrodes.6 Non-aqueous solvents, on the other hand, exhibit wider electrochemical potential windows, offering the possibility for higher power and energy densities. Several non-aqueous electrolytes using metal-ligand complexes as the active-redox species in organic solvents have exhibited cell potentials ab...

Modulation of the ligand structure results in complex solubilities that can varied by more than four orders of magnitude. The most soluble of these complexes yields an electrolyte with theoretical energy densities 6-fold higher than commercial aqueous vanadium RFBs.

We performed an extensive analysis about the reaction conditions of the 1,4-Michael addition of amino acids to 1,4-naphthoquinone and substitution to 2,3-dichloronaphthoquinone, and a complete evaluation of stoichiometry, use of different bases, and the pH influence was performed. We were able to show that microwave-assisted synthesis is the best method for the synthesis of naphthoquinone–amino acid and chloride–naphthoquinone–amino acid derivatives with 79–91% and 78–91% yields, respectively. The cyclic voltammetry profiles showed that both series of naphthoquinone–amino acid derivatives mainly display one quasi-reversible redox reaction process. Interestingly, it was shown that naphthoquinone derivatives possess a selective antitumorigenic activity against cervix cancer cell lines and chloride–naphthoquinone–amino acid derivatives against breast cancer cell lines. Furthermore, the newly synthetized compounds with asparagine–naphthoquinones (3e and 4e) inhibited ~85% of SiHa cell proliferation. These results show promising compounds for specific cervical and breast cancer treatment.

A novel material, with a general formula of IrSn-Sb-O, was synthesized for use in solid polymer electrolyte water electrolyzers (SPEWEs) by the thermal decomposition of the chloride precursors H 2 IrCl 6 , SnCl 4 Á5H 2 O, and SbCl 3 in ethanol. The material functions simultaneously as an electrocatalyst and support for the oxygen evolution reaction (OER). Two different H 2 IrCl 6 proportions in the reaction mixture were tested to observe the effect of this proportion on the electrocatalytic activity and composition of the materials. Physicochemical properties of Ir-Sn-S-O were characterized by X-ray diffraction, scanning electron microscopy. The electrochemical properties of the materials studied were measured using cyclic voltammetry, linear scan voltammetry, and electrochemical impedance spectroscopy. Mechanical mixtures of IrO 2 with Vulcan carbon or antimony doped tin oxide were also tested with respect to the OER to compare the properties of Ir-Sn-Sb-O. The results indicate that the catalyst-support materials presented nanometric sizes (1-2 nm) and electrocatalytic properties similar to IrO 2 supported on Vulcan carbon but with higher stability toward the oxygen evolution reaction. The synthesized mixed oxides could be a suitable anode material in SPEWEs.