A high-performance carbon nanoparticle-decorated graphite felt electrode for vanadium redox flow batteries

Increasing the performance of vanadium redox flow batteries (VRFBs), especially the energy efficiency and power density, is critically important to reduce the system cost to a level for widespread commercialization. Unlike conventional VRFBs with flow-through structure, in this work we create a VRFB featuring a flow-field structure with a carbon nanoparticle-decorated graphite felt electrode for the battery. This novel structure, exhibiting a significantly reduced ohmic loss through reducing electrode thickness, an increased surface area and improved electrocatalytic activity by coating carbon nanoparticles, allows the energy efficiency up to 84.8% at a current density of as high as 100 mA cm−2 and the peak power density to reach a value of 508 mW cm−2. In addition, it is demonstrated that the battery with this proposed structure exhibits a substantially improved rate capability and capacity retention as opposed to conventional flow-through structured battery with thick graphite felt electrodes.