Controlling the rate of posolyte degradation in all-quinone aqueous organic redox flow batteries by sulfonated nanocellulose based membranes: The role of crossover and Michael addition

Abstract

Aqueous organic redox flow battery (AORFB) is a technological route towards the large-scale sustainable energy storage. However, several factors need to be controlled to maintain the AORFB performance. Prevention of posolyte and negolyte cross-contamination in asymmetric AORFBs, one of the main causes of capacity decay, relies on their membranes' ability to prevent migration of the redox-active species between the two electrolytes. The barrier properties are often traded for a reduction in ionic conductivity which is crucial to enable the device operation. Another factor greatly affecting quinone-based AORFBs is the Michael addition reaction (MAR) on the charged posolyte, quinone, which has been identified as a major reason for all-quinone AORFBs performance deterioration. Herein, we investigate deterioration scenarios of an all-quinone AORFB using both experimental and computational methods. The study includes a series of membranes based on sulfonated cellulose nanofibrils and different membrane modifications. The layer-by-layer (LbL) surface modifications, i.e. the incorporation of inorganic materials and the reduction of the pore size of the sulfonated cellulose membranes, were all viable routes to reduce the passive diffusion permeability of membranes which correlated to an increased cycling stability of the battery. The kinetics of MAR on quinone was detected using NMR and its impact on the performance fading was modeled computationally. The localization of MAR close to the membrane, which can be assigned to the surface reactivity, affects the diffusion of MAR reagent and the deterioration dynamics of the present all-quinone AORFB.