Durable alkaline zinc-iron flow batteries using a SPEEK/Polysulfone blend membrane

Abstract

Alkaline zinc-iron flow batteries (AZIFBs) are regarded as one of the most promising candidates for energy storage systems (ESSs). Although they have advantages, such as scalability, safety, and long cycle life, there are remaining disadvantages - crossover and zinc dendrite formation. To address these issues, we introduce a blend polymer membrane for a stable zinc-iron flow battery system with enhanced alkaline stability and dendrite-free operation. The SPEEK/Polysulfone (SPK/PS) blend membrane demonstrates balanced properties of high ion selectivity, high mechanical strength, and chemical stability, which enhances its cyclability and durability, showing stable long-term performance with energy efficiency of 80.0% for 700 cycles at a current density of 80 mA cm- 2 using a state of charge (SOC) of 50%. This study offers an effective approach for alkaline zinc-based batteries, providing stability in alkaline environments.