Exploring the Effectiveness of Carbon Cloth Electrodes for All-Vanadium Redox Flow Batteries

Abstract

Redox flow batteries (RFBs) have proven to be a promising technology for the integration of intermittent renewable energy sources into the existing electrical grid due to their ability to decouple energy and power ratings, and the associated cost-effectiveness in long-duration energy storage [1]. Among various flow battery chemistries, vanadium redox flow battery (VRFB) is one of the most prominently studied flow battery system [2]. In comparison to other chemistries, four soluble oxidation states of vanadium are available and accessible. This characteristic of VRFBs eliminates cross-contamination between the positive and negative half-cells that would otherwise deteriorate the life and durability of the battery [3]. In a flow battery cell, porous electrode is the key component that determines the performance of the system by delivering liquid electrolytes, facilitating ion/charge transfer, and providing sites for electrochemical reactions [4]. Recently, it has been found that significant performance improvements can be achieved with fabric (carbon cloth) electrodes when coupled with a wetting electrolyte [5].In this talk, we will report our experimental approach to evaluate the short- and long-term effectiveness of various carbon cloth electrode samples for use in VRFBs. Results generated from symmetric flow cell cycling coupled with electrochemical impedance spectroscopy and polarization curve measurements will be discussed. The key physico-chemical properties and their evolution during cycling will be elucidated.