Computational and experimental investigation of the effect of cation structure on the solubility of anionic flow battery active-materials.

Recent advances in clean, sustainable energy sources such as wind and solar have enabled significant cost improvements, yet their inherent intermittency remains a considerable challenge for year-round reliability demanding the need for grid-scale energy storage. Nonaqueous redox flow batteries (NRFBs) have the potential to address this need, with attractive attributes such as flexibility to accommodate long- and short-duration storage, separately scalable energy and power ratings, and improved safety profile over integrated systems such as lithium-ion batteries. Currently, the low-solubility of NRFB electrolytes fundamentally limits their energy density. However, synthetically exploring the large chemical and parameter space of NRFB active materials is not only costly but also intractable. Here, we report a computational framework, coupled with experimental validation, designed to predict the solubility trends of electrolytes, incorporating both the lattice and solvation free energies. We reveal that lattice free energy, which has previously been neglected, has a significant role in tuning electrolyte solubility, and that solvation free energies alone is insufficient. The desymmetrization of the alkylammonium cation leading to short-chain, asymmetric cations demonstrated a modest increase in solubility, which can be further explored for NRFB electrolyte development and optimization. The resulting synergistic computational-experimental approach provides a cost-effective strategy in the development of high-solubility active materials for high energy density NRFB systems.

Designing high energy density flow batteries by tuning active-material thermodynamics.

The cost of electricity generated by wind and solar installations has become competitive with that generated by burning fossil fuels. While this paves the way for a carbon-neutral electrical grid, short- and long-term intermittency necessitates energy storage. Flow batteries are a promising technology to accommodate this need, with numerous advantages, including decoupled power and energy ratings, which imparts flexibility, thermal stability, and safety. Further, development of robust nonaqueous systems has the potential to greatly improve energy density, approaching that of lithium-ion batteries, while maintaining the advantages of flow systems. Herein we report a breakthrough on a bio-inspired nonaqueous redox flow battery (NRFB) electrolyte, which contains high-concentration active-material and maintains stability during deep cycling for extended time-periods. These advances are reinforced by thermodynamic considerations and computational investigations, which provide a clear path to further improvements. Electrochemical studies confirm that the active-material maintains its high stability at high concentration. This molecular scaffold clears two important hurdles in designing active-materials for nonaqueous electrolytes - low solubility and poor stability - providing an in-road to development of high-performance NRFB systems.

A novel approach for the fabrication of a flexible glucose biosensor: The combination of vertically aligned CNTs and a conjugated polymer.

A novel flexible glucose biosensor using vertically aligned carbon nanotubes (VACNT) and a conjugated polymer (CP) was fabricated. A scaffold based on VACNT grown on aluminum foil (VACNT-Al foil) with poly (9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl)-end capped with 2,5-diphenyl-1,2,4-oxadiazole (PFLO) was used as the immobilization matrix for the glucose biosensor. Glucose oxidase (GOx) was immobilized on a modified indium tin oxide (ITO) coated polyethylene terephthalate (PET) electrode surface. The biosensor response at a potential of -0.7V versus Ag wire was followed by the decrease in oxygen level as a result of enzymatic reaction. The biosensor exhibited a linear range between 0.02mM and 0.5mM glucose and kinetic parameters (KMapp, Imax, limit of detection (LOD) and sensitivity) were estimated as 0.193mM, 8.170µA, 7.035×10-3mM and 65.816µA/mMcm2, respectively. Scanning electron microscopy (SEM) was used for surface characterization. The constructed biosensor was applied to determine the glucose content in several beverages.

Selenium containing conducting polymer based pyranose oxidase biosensor for glucose detection.

A novel amperometric pyranose oxidase (PyOx) biosensor based on a selenium containing conducting polymer has been developed for the glucose detection. For this purpose, a conducting polymer; poly(4,7-bis(thieno[3,2-b]thiophen-2-yl)benzo[c][1,2,5] selenadiazole) (poly(BSeTT)) was synthesized via electropolymerisation on gold electrode to examine its matrix property for glucose detection. For this purpose, PyOx was used as the model enzyme and immobilised via physical adsorption technique. Amperometric detection of consumed oxygen was monitored at -0.7 V vs Ag reference electrode in a phosphate buffer (50 mM, pH 7.0). K(M)(app), Imax, LOD and sensitivity were calculated as 0.229 mM, 42.37 nA, 3.3 × 10(-4)nM and 6.4 nA/mM cm(2), respectively. Scanning electron microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS) and cyclic voltammetry (CV) techniques were used to monitor changes in surface morphologies and to run electrochemical characterisations. Finally, the constructed biosensor was applied for the determination of glucose in beverages successfully.