Aligned Carbon Nanotube Polymer Nanocomposite Bipolar Plates Technology for Vanadium Redox Flow Batteries

Bipolar plates (BPs) are essential multifunctional components in vanadium redox flow batteries (VRFBs) that require excellent electrical conductivity, low permeability, and strong solid support for the stack. However, conventional BPs are based on graphite sheets, which provide mechanical properties and corrosion resistance but have limitations in terms of electrical conductivity. Although carbon nanotubes (CNTs) have excellent properties, CNT composites with low CNT volume fractions (10–20%) have increased electrolyte permeability and limited electrical conductivity improvement, resulting in low durability and efficiency for VRFBs. This study proposes a novel concept of horizontally aligned CNT nanocomposite bipolar plate (HACN-BP) to address these issues. The HACN-BPs feature an optimized conduction path with a CNT volume fraction of 59%, resulting in reduced manufacturing time while demonstrating superior conductivity and permeability compared to conventional BPs. Furthermore, integrated HACN-BP mitigates ohmic loss that occurs in the BPs, thereby mitigating the potential drop by 40%. Therefore, the utilization of HACN-BP shows superior performance compared to recent studies, a substantial improvement of more than 6% in energy efficiency and 14% in capacity over conventional BP.