Reducing parasitic currents in acid-base flow batteries by decreasing the manifold cross-sectional area: Experiments and modelling.

[Display omitted] • Experimental and modelling investigation on one method to reduce parasitic currents; • Proposed design to reduce ionic shortcut currents using manifold reducers; • Pressure losses were quantified with and without the presence of manifold reducers; • The model was able to calculate parasitic currents and how they varied in the stack; • The design was found to improve the performance of Acid-Base Flow Battery systems. The Acid-Base Flow Battery is an innovative and sustainable electrochemical storage system storing energy in the form of salinity and pH gradients. However, parasitic currents via manifolds dramatically affect system by reducing its Round-Trip Efficiency (RTE). This work experimentally studies this phenomenon using a purposely designed methodology involving sticks placed in the manifold ducts. Various figures of merit were calculated to evaluate battery performance in the charge and discharge phases. A mathematical model was validated and applied to investigate the ionic parasitic currents. The results highlighted the importance of studying this phenomenon, as achieving a reduction in the parasitic currents caused a 25% increase in the net power and more than tripled the RTE compared to the reference configuration without sticks. Although reducing manifold diameter increases pumping losses, it was found to be anyway really beneficial for the process performance and paves the way for future, more suitable, battery designs. [ABSTRACT FROM AUTHOR]