Propylene carbonate-derived size modulation of water cluster in pore-filled Nafion/polypropylene composite membrane for the use in vanadium redox flow batteries

The Critical Analysis of Membranes toward Sustainable and Efficient Vanadium Redox Flow Batteries

Vanadium redox flow batteries (VRFB) are a promising technology for large-scale storage of electrical energy, combining safety, high capacity, ease of scalability, and prolonged durability; features which have triggered their early commercial implementation. Furthering the deployment of VRFB technologies requires addressing challenges associated to a pivotal component: the membrane. Examples include vanadium crossover, insufficient conductivity, escalated costs, and sustainability concerns related to the widespread adoption of perfluoroalkyl-based membranes, e.g., perfluorosulfonic acid (PFSA). Herein, recent advances in high-performance and sustainable membranes for VRFB, offering insights into prospective research directions to overcome these challenges, are reviewed. The analysis reveals the disparities and trade-offs between performance advances enabled by PFSA membranes and composites, and the lack of sustainability in their final applications. The potential of PFSA-free membranes and present strategies to enhance their performance are discussed. This study delves into vital membrane parameters to enhance battery performance, suggesting protocols and design strategies to achieve high-performance and sustainable VRFB membranes.

An Electrolyte with Elevated Average Valence for Suppressing the Capacity Decay of Vanadium Redox Flow Batteries

Nafion series membranes are widely used in vanadium redox flow batteries (VRFBs). However, the poor ion selectivity of the membranes to vanadium ions, especially for V²⁺, results in a rapid capacity decay during cycling. Although tremendous efforts have been made to improve the membrane's ion selectivity, increasing the ion selectivity without sacrificing the proton conductivity is still a challenging issue. In this work, instead of focusing on enhancing the membranes' ion selectivity, we develop an efficient valence regulation strategy to suppress the capacity decay caused by the crossover of V²⁺ in VRFBs. Despite the discharge capacity of the VRFB with the elevated average valence electrolytes (V^3.68+) being slightly lower than that with commercial electrolytes (V^3.50+) in the first 35 cycles, the accumulated discharge capacity in 400 cycles is improved by 52.33%. Moreover, this method is efficient, is easy to scale up, and provides deep insights into the capacity decay mechanism of VRFBs.

High-performance photocatalytic membranes for water purification in relation to environmental and operational parameters

Growing technologies, increasing population and environmental pollution lead to severe contamination of water and require advanced water treatment technologies. These aspects lead to the need to purify water with advanced smart materials. This paper reviews the recent advances (during the last 5 years) in photocatalytic composite membranes used for water treatment. For this purpose, the authors have reviewed the main materials used in the development of (photocatalytic membranes) PMs, environmental and operational factors affecting the performance of photocatalytic membranes, and the latest developments and applications of PMs in water purifications. The composite photocatalytic membranes show good performance in the removal and degradation of pollutants from water.