Synthesis and characterization of bromine complexing agents for zinc bromine flow batteries

Las baterías de flujo son dispositivos recargables, donde el electrolito (que tiene una o más especies activas) fluye a través de la celda electroquímica y transforma la energía química en energía eléctrica, y viceversa. Una característica de este tipo de baterías es el desacoplamiento de potencia y capacidad energética, debido a que el almacenamiento del electrolito se encuentra fuera de la celda electroquímica En esta tecnología energética, las baterías de flujo de zinc-bromo (ZBFB) constituyen uno de los sistemas más prometedores en términos de economía, disponibilidad de materiales y rendimiento. Los agentes complejantes de bromo (BCA) son esenciales para el correcto funcionamiento de estas baterías de flujo, actuando como captadores de bromo. Estos BCA son aminas cuaternarias sintetizadas mediante una reacción de sustitución bimolecular especial (SN2), conocida como reacción Menshutkin. Los BCA más utilizados en ZBFB debido a su notable rendimiento son el bromuro de 1-etilmetilmorfolinio (MEM-Br) y el bromuro de N-etilmetilpirrolidinio (MEP-Br). En este trabajo de tesis doctoral se ha estudiado la síntesis de diferentes BCA como alternativas innovadoras a los tradicionales compuestos MEM-Br y MEP-Br. Los BCA sintetizados se han caracterizado con técnicas estructurales, fisicoquímicas y electroquímicas, utilizándolos en baterías ZBFB como agentes complejantes. Para ello, se han preparado diferentes electrolitos a partir de los BCA sintetizados y se han ensamblado celdas ZBFB con todos sus componentes de diseño propio, como son la celda electroquímica, depósitos, bombas y circuito hidráulico, para su posterior análisis de rendimiento electroquímico mediante test de ciclos galvanostáticos de carga y descarga. Los positivos resultados logrados en aspectos como el proceso de síntesis, y las eficiencias coulómbica y energética de las baterías demuestran que los BCA sintetizados son realmente prometedores para el próximo desarrollo de baterías de flujo Zn-Br de altas prestaciones

Enhanced Performance of Zn/Br Flow Battery Using N-Methyl-N-Propylmorpholinium Bromide as Complexing Agent

Redox flow batteries (RFB) are one of the most interesting technologies in the field of energy storage, since they allow the decoupling of power and capacity. Zinc–bromine flow batteries (ZBFB) are a type of hybrid RFB, as the capacity depends on the effective area of the negative electrode (anode), on which metallic zinc is deposited during the charging process. Gaseous bromine is generated at the positive electrode (cathode) during the charging process, so the use of bromine complexing agents (BCA) is very important. These BCAs are quaternary amines capable of complexation with bromine and generating an organic phase, immiscible with the aqueous electrolyte. One of the most commonly used BCAs in RFB technology is 4-methylethylmorpholinium bromide (MEM-Br). In this work, an alternative quaternary amine 4-methylpropylmorpholinium bromide (MPM-Br) was studied. MPM-Br was integrated into the electrolyte, and 200 charge–discharge cycles were performed on the resulting ZBFBs. The obtained results were compared with those when MEM-Br was used, and it was observed that the electrolyte with MPM-Br displays a higher resistance in voltage and higher energy efficiency, making it a promising alternative to MEM-Br

Recent Advances in Bromine Complexing Agents for Zinc–Bromine Redox Flow Batteries

The development of energy storage systems (ESS) has become an important area of research due to the need to replace the use of fossil fuels with clean energy. Redox flow batteries (RFBs) provide interesting features, such as the ability to separate the power and battery capacity. This is because the electrolyte tank is located outside the electrochemical cell. Consequently, it is possible to design each battery according to different needs. In this context, zinc–bromine flow batteries (ZBFBs) have shown suitable properties such as raw material availability and low battery cost. To avoid the corrosion and toxicity caused by the free bromine (Br2) generated during the charging process, it is necessary to use bromine complexing agents (BCAs) capable of creating complexes. As an overview, the different BCAs used have been listed to compare their behavior when used in electrolytes in ZBFBs. In addition, the coulombic and energy efficiencies obtained have been compared

Recent advances in bromine complexing agents for zinc–bromine redox flow batteries

The development of energy storage systems (ESS) has become an important area of research due to the need to replace the use of fossil fuels with clean energy. Redox flow batteries (RFBs) provide interesting features, such as the ability to separate the power and battery capacity. This is because the electrolyte tank is located outside the electrochemical cell. Consequently, it is possible to design each battery according to different needs. In this context, zinc–bromine flow batteries (ZBFBs) have shown suitable properties such as raw material availability and low battery cost. To avoid the corrosion and toxicity caused by the free bromine (Br2) generated during the charging process, it is necessary to use bromine complexing agents (BCAs) capable of creating complexes. As an overview, the different BCAs used have been listed to compare their behavior when used in electrolytes in ZBFBs. In addition, the coulombic and energy efficiencies obtained have been compared