Redox flow batteries are well suited for large-scale electrical energy storage, yet their deployment remains hampered by technical and economic challenges. Within the electrochemical cell, the flow field geometry determines the electrolyte pumping power required, mass transport rates, and overall cell performance. However, current designs are inspired on fuel cell technologies but have not been engineered for redox flow battery applications where liquid-phase electrochemistry is sustained. Here, we leverage stereolithography 3D printing to manufacture lung-inspired flow field geometries and compare their performance to conventional flow field designs. A versatile two-step process based on stereolithography 3D printing followed by a coating procedure to form a conductive structure is developed to manufacture lung-inspired flow field geometries. We employ a suite of fluid dynamics, electrochemical diagnostics and finite element simulations to correlate the flow field geometry with performance in symmetric flow cells. The lung-inspired structural pattern is demonstrated to homogenize the reactant distribution in the porous electrode and to improve the electrolyte accessibility to the electrode reaction area. In addition, the results reveal that these novel flow field geometries can outperform traditional interdigitated flow field designs, as these patterns exhibit a more favorable electrical and pumping power balance, achieving superior current densities at lower pressure loss. Although at its nascent stage, additive manufacturing offers a versatile design space for manufacturing engineered flow field geometries for emerging redox flow batteries and other electrochemical energy storage technologies.

Agradecimientos y a Ana, gracias por todo lo que me habéis enseñado y demostrarme que no hay que rendirse nunca. A mis abuelos, Juan (Lara) y Mariló, Juan (Cuadra) y Charo, y Juan (Gutierrez) y Mari, por vuestra valiosa ayuda a lo largo de mi vida. A mis hermanos, Javi, María, David y Laura, de quienes continúo aprendiendo constantemente. Sois luz, gracias por enseñarme tanto. A Sandra, Rubén, Sensi y, por supuesto, Aroa, por llegar a nuestras vidas. A Carmen, por darme tan buenos consejos y hacerme sentir como en casa. A mis tíos, especialmente a Juan (Lara), Caroli, Mari Carmen, Estrella, Jessi, Fran, Elena, José Manuel y Flas, gracias por vuestro apoyo y hacerme crecer como persona. Estéis donde estéis, Juan (Cuadra) y Diego, me habría encantado hablar de ciencia con vosotros. A mis primos, en especial a Mari Carmen (Cuadra), Juan y Gonzalo. Sois todos magníficos y no hay palabras suficientes para describir lo que significáis para mí. Habéis contribuido a mi crecimiento personal, y espero seguir mejorando a vuestro lado. Este trabajo va dedicado a todos vosotros.

más rápida cuando se retienen los efectos de densidad variable, mientras que la respuesta en amplitud cambia muy poco cuando se retienen las variaciones de densidad. También se discuten brevemente las dificultades que surgen cuando la capa de mezcla constituye además una entrefase de densidad. Para ello, se presenta una solución exacta de las ecuaciones de Euler para la propagación de torbellinos en presencia de entrefases abruptas de densidad que permite aclarar algunos aspectos relevantes de este tipo de flujos.

Electrochemical flow reactors are increasingly relevant platforms in emerging sustainable energy conversion and storage technologies. As a prominent example, redox flow batteries, a well-suited technology for large energy storage if the costs can be significantly reduced, leverages electrochemical reactors as power converting units. Within the reactor, the flow field geometry determines the electrolyte pumping power required, mass transport rates, and overall cell performance. However, current designs are inspired on fuel cell technologies but have not been engineered for redox flow battery applications where liquid-phase electrochemistry is sustained. Here, we leverage stereolithography 3D printing to manufacture lung-inspired flow field geometries and compare their performance to conventional flow field designs. A versatile two-step process based on stereolithography 3D printing followed by a coating procedure to form a conductive structure is developed to manufacture lung-inspired flow field geometries. We employ a suite of fluid dynamics, electrochemical diagnostics and finite element simulations to correlate the flow field geometry with performance in symmetric flow cells. The lung-inspired structural pattern is demonstrated to homogenize the reactant distribution in the porous electrode and to improve the electrolyte accessibility to the electrode reaction area. In addition, the results reveal that these novel flow field geometries can outperform traditional interdigitated flow field designs, as these patterns exhibit a more favorable electrical and pumping power balance, achieving superior current densities at lower pressure loss. Although at its nascent stage, additive manufacturing offers a versatile design space for manufacturing engineered flow field geometries for advanced flow reactors in emerging electrochemical energy storage technologies.