Novel results concerning the inverse vulcanization of sulfur using reversible addition-fragmentation chain transfer (RAFT) polymerization are here reported. It is shown that RAFT polymerization can be used to carry out this cross-linking process, with the additional possibility to extend the reaction time from a few minutes as with classical free radical polymerization (FRP) to several hours. Higher control on viscosity and processability of the synthesized networks, as well as, the implementation of semibatch feed policies during cross-linking are important advantages of the RAFT process here explored comparatively to the FRP inverse vulcanization. Using cyclic voltammetry, it was assessed the electrochemical activity of the synthesized sulfur-rich polymer networks. It is shown that the fundamental electrochemical activity of the elemental sulfur was preserved in the produced materials. Testing of electrochemical cells assembled with lithium in the anode and different sulfur based materials in the cathode, including the synthesized RAFT networks, is also shown. The results here presented highlight the new opportunities introduced by reversible-deactivation radical polymerization mechanisms on the control of the synthesis process and in the design of such advanced materials and show also that many potential derivatizing possibilities can be achieved.

A simple in-situ method for the quantification of the crossover in redox flow batteries, adapted from an electrochemical method currently used for quantifying the hydrogen crossover in fuel cells, is proposed and used for characterizing a vanadium redox flow battery. A linear sweep voltammetry (LSV) scan is performed with the pertinent redox species in one side of the electrochemical cell, while in the other side is the supporting electrolyte. The LSV plot should display a plateau where the current is limited by the crossover of the selected species. The crossover results were compared with an external analytical method using MP-AES, showing very good agreement with a maximum relative difference of 6%. This method was used to quantify the crossover of all vanadium species using both cation and anion exchange membranes. The proposed method can be applied for assisting the development and characterization of ion-exchange membranes for redox flow batteries and for in-situ diagnosis of component degradation and failure in RFB systems without disassembling them.

The current work assesses the impact of structural differences between stable and metastable ZrO2 precursors on the mechanochemical preparation of BaZrO3. Monoclinic (m-ZrO2) and tetragonal (t-ZrO2) zirconia polymorphs were prepared without stabilizing additives by slow alkaline precipitation. High-energy milling of the individual ZrO2 precursors induced different partial transformations in each case. The as-synthesized m-ZrO2 powders showed partial conversion to the tetragonal polymorph on mechanical activation, reaching about 10% t-ZrO2 after 420 min accompanied by increases in strain. In contrast, the as synthesized t-ZrO2 powders underwent the inverse transformation to the monoclinic phase, producing about 50% m-ZrO2 after 120 min with the liberation of strain. The t-ZrO2 precursor was shown to exhibit the higher reactivity with barium peroxide, yielding significantly earlier formation of barium zirconate under room-temperature mechanosynthesis. The progress of the mechanochemical formation of BaZrO3 has been discussed with respect to the differing behaviour of the ZrO2 precursors upon mechanical activation and associated thermodynamic perspectives.

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