The zinc-bromine redox flow battery (RFB) is one of a very few commercially viable RFB energy storage systems capable of integration with intermittent renewable energy sources to deliver improved energy management. However, due to the volatility of the electrogenerated bromine and potential for its crossover from positive to negative electrolytes, this system requires the use of quaternary ammonium complexes (N-methyl-N-ethylpyrrolidinium, (MEP)) to capture this bromine. This produces an immiscible phase with the Br 2 which requires a complex network of pipes, pumps and automated controls to ensure access to the electroactive material during discharge. In this work, the use of novel quaternary ammonium complexes to capture the electrogenerated bromine but to keep it in the aqueous phase is examined. Three compounds, 1-(carboxymethyl) pyridine-1-ium, 1-(2-carboxymethyl)-1-methylmorpholin-1-ium and 1-(2-carboxymethyl)-1-methylpyrrolidin-1-ium, were found to successfully reduce the volume of the immiscible phase formed on complexing with the polybromide (Br x − ) whilst displaying similar enthalpy of vaporization values as that of MEP . Electrochemical analysis also revealed that these compounds did not impact on the electrode kinetics of the Br − /Br x − reaction indicating that the resulting surface film formed with these compounds behaved as a chemically modified electrode, in contrast to the surface film formed with MEP. Renewable energy features in many countries' energy agendas. Current political focus seeks to reduce carbon emissions, as agreed by the Paris Agreement, by using energy more efficiently and to have power generation from zero carbon technologies.1 Installed capacity of renewable energy sources have increased over the decade to 2014 by 175 GW for solar and by 322 GW for wind.2 This increase in capacity has impacted on the global share of energy from renewable sources (excluding hydropower) from 2.2% (2004) to 9.7% (2013) with many countries promising to accelerate their installation of these technologies in the coming years.3 However, energy supplied from renewable sources is often intermittent and can fluctuate depending on weather and location. 4,5 This creates a problem in that energy can be generated in excess or in deficit in relation to energy demand. To solve this issue, energy storage is required to balance these peaks and troughs in order to stabilize energy flow into the electrical grid. This would lead to a better management of renewable sources. 6 Redox flow batteries (RFBs) are one means of achieving large scale energy storage which can provide a more efficient link between energy production and energy demand. This type of battery system has the advantage of having a lower cost, a low level of self-discharge and is considered to have a much safer operation compared to other battery systems such as the sodium sulfur and lithium ion batteries. 7,8 Additionally, as with all batteries, it has the advantage of being more flexible and mobile in relation to pumped hydro and compressed air t...

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The specular reflectance from a hexagonal array of gold nanorods embedded in an alumina matrix supported on an aluminum substrate is reported. The rods were grown by electrodeposition of gold in an alumina template and were oriented with their long axis perpendicular to the film surface. Optical reflectance measurements performed with an incident light beam of S polarization only exhibited the transverse surface plasmon resonance whereas the measurements obtained with P polarization exhibited both transverse and longitudinal resonances. A model for the reflectance from a thin anisotropic film was developed and shown to be in agreement with the experimental data

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Zinc-bromine redox flow batteries (RFB) are energy storage devices capable of integrating with renewable generators and so improve energy management from these intermittent sources. However, this system is susceptible to self-discharge via the electrogenerated bromine transferring through the separator and reacting with the plated zinc. Here we examine the use of novel quaternary ammonium complexes to capture the electrogenerated bromine but keep it in the aqueous phase (as opposed to the immiscible phase formed with N-methyl-N-ethylpyrrolidinium, MEP). Electrochemical analysis indicates that these complexes do not impact on the electrode kinetics and exhibit similar physical properties as to the MEP. However, the latter still shows an enhanced ability to complex the bromine to higher polybromide states (i.e. Br 5 −).