Li–O2 battery technology offers large theoretical energy density, considered a promising alternative energy storage technology for a variety of applications. One of the main advances made in recent years is the use of soluble catalysts, known as redox mediators (RM), decreasing the charge overpotential and improving cyclability. Despite its potential, much is still unknown regarding its dynamic, especially over higher loading electrodes, where mass transport may be an issue and the interplay with common impurities in the electrolyte, like residual water. Here we perform for the first time an operando XRD characterization of a DMSO-based LiBr mediated Li–O2 battery with a high loading electrode based on CNTs aiming to reveal these dynamics and track chemical changes in the electrode. Our results show that, depending on the electrode architecture, the system’s issue can move from catalytic to a mass transfer. We also assess the effect of residual water in the system to better understand the reaction routes. As a result, we observed that with DMSO, the system is even more sensitive to water contamination compared to glyme-based studies reported in the literature. Despite the activity of LiBr on the Li-peroxide oxidation and its contribution to cyclability, with the system and electrode configuration used in this study, we verified that a mass transfer limitation caused a cell “sudden death” caused by clogging after cycling.

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Metal–air batteries, such as Li–air, may be the key for large‐scale energy storage as they have the highest energy density among all electrochemical devices. However, these devices suffer from irreversible side reactions leading to battery failure, especially when ambient air is used as the O2 source, so a deep understanding over the surface chemistry evolution is imperative for building better devices. Herein, a multi‐scale (nano‐micro) FTIR analysis is made over the electrode surface during cell discharge employing synchrotron infrared nanospectroscopy (SINS) for the first time, to track the chemical composition changes at the nanoscale which are successfully correlated with in operando micro‐FTIR characterization. The in situ results reveal homogeneous product distribution from the nano to the micro scale, and that the discharge rate does not interfere in chemical composition. In operando micro‐FTIR shows the atmosphere dependency over Li products formation; the presence of HCOO– species occurring due to CO2 electroreduction in water, LiOH and Li2CO3, are also detected and even the lowest concentration of CO2 and H2O affects the O2 reactions. Finally, evidence of the Li2O2 reaction with DMSO forming DMSO2 after just 140 s of cell discharge shows this new technique's relevance in aiding the search for stable electrolytes.

A obtenção da cera encontrada no farelo do arroz é uma alternativa de promover a valorização deste co-produto agroindustrial. O hexano é o solvente mais comumente empregado em processos de extração de lipídios, porém o seu uso está associado à efeitos nocivos para a saúde e ao meio ambiente. Desta forma, este trabalho teve como objetivo avaliar a utilização de diferentes biosolventes (etanol, propanol, butanol e limoneno), além do teor de umidade, granulometria, quantidade de solvente e tempo na extração da cera do farelo de arroz.

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