RESUMO
Rechargeable zinc batteries (RZBs) are highly attractive as energy storage solutions due to their low cost and sustainability. Nevertheless, the use of fluorine-free zinc electrolyte systems to create affordable, ecofriendly, and safe RZBs has been largely overlooked in the battery community. Previously, we showcased the utilization of a fluorine-free, nonaqueous electrolyte comprising zinc dicyanamide (Zn(dca)2) in dimethyl sulfoxide (DMSO) to enable the electrochemical cycling of zinc. Herein we present a dual-cation-based electrolyte, [1.0 M Na(dca) +1.0 M Zn(dca)2]/DMSO, in pursuit of a rechargeable zinc hybrid battery. Fourier-transform infrared spectroscopy and molecular dynamics simulation studies indicate that the presence of Na(dca) diminishes ion-pairing in Zn(dca)2 through [dca]- anion bridging between Zn2+ and Na+ ions, thereby enhancing Zn2+ ion transport in the electrolyte. Thus, the electrolyte exhibits high ionic conductivity and transference numbers (tZn2+) of 7.9 mS cm-1 and 0.83, respectively, at 50 °C, making it particularly suitable for high-temperature battery applications. Furthermore, we demonstrate, for the first time, the cycling of a full cell with a zinc anode and triphylite sodium iron phosphate cathode (NFP) in an organic electrolyte, showcasing stable performance over 100 cycles at 0.1C rate. These encouraging findings pave the way for affordable battery technologies using, fluorine-free electrolyte.
RESUMO
In order to bridge the gap between theoretical and practical energy density in sodium oxygen batteries challenges need to be overcome. In this work, four commercial air cathodes were selected, and the impacts of their morphologies, structure and chemistry on their performance with a pyrrolidinium-based ionic liquid electrolyte are evaluated. The highest discharge capacity was found for a cathode with a pore size ca. 6 nm; this was over 100 times greater than that delivered by a cathode with a pore size less than 2 nm. The air cathode with the highest specific surface area and the presence of a microporous layer (BC39) exhibited the highest specific capacity (0.53 mAh cm-2).
RESUMO
Sodium-oxygen (Na-O2) cells are a promising high energy density storage technology with a theoretical specific energy of 1605 Wh kg-1. However, this technology faces certain challenges in order to achieve both a high practical energy density as well as long-term cycling capability. In this Letter, a superior Coulombic cyclic efficiency, close to 100%, has been demonstrated by the use of a bilayer electrolyte composed of an ionogel and an ionic liquid electrolyte, reported herein for the first time. The presence of the ionogel plays a major role in the prevention of side reactions originating at the anode, providing a promising route to extend cell cycling, whereas the ionic liquid is essential to support high reaction rates at the cathode.