No abstract

The need for large scale energy storage has become a priority to integrate renewable energy sources into the electricity grid. Redox flow batteries are considered the best option to store electricity from medium to large scale applications. However, the current high cost of redox flow batteries impedes the wide spread adoption of this technology. The membrane is a critical component of redox flow batteries as it determines the performance as well as the economic viability of the batteries. The membrane acts as a separator to prevent cross-mixing of the positive and negative electrolytes, while still allowing the transport of ions to complete the circuit during the passage of current. An ideal membrane should have high ionic conductivity, low water intake and excellent chemical and thermal stability as well as good ionic exchange capacity. Developing a low cost, chemically stable membrane for redox flow cell batteries has been a major focus for many groups around the world in recent years. This paper reviews the research work on membranes for redox flow batteries, in particular for the all-vanadium redox flow battery which has received the most attention.

Over the past three decades, intensive research activities have focused on the development of electrochemical energy storage devices, particularly exploiting the concept of flow batteries. Amongst these, vanadium redox flow batteries (VRFB) are an attractive option, which have been studied extensively and are now being commercialized around the world. The performance of the VRFB system is governed by several critical components namely the electrolyte, the electrode, the ion‐exchange membrane and the flow field design. Here, the focus is mainly on recent research activities relating to the development and modification of electrode materials and new ion‐exchange membranes. The feasibility of novel flow field designs for high energy density VRFB systems and their future prospects are also discussed in detail.