Assessing the levelized cost of vanadium redox flow batteries with capacity fade and rebalancing

Redox flow batteries (RFBs) are an emerging technology suitable for grid electricity storage. The vanadium redox flow battery (VRFB) has been one of the most widely researched and commercialized RFB systems because of its ability to recover lost capacity via electrolyte rebalancing, a result of both the device configuration as well as the symmetry of the redox chemistry. Despite broad acknowledgement of the benefits of this differentiating feature to system resilience and longevity, assessments of its economic value to the VRFB system have thus far been limited. Here we develop a techno-economic framework that incorporates a physical model of capacity fade and recovery from rebalancing and other servicing methods into a levelized cost of storage (LCOS) metric. We then evaluate the impacts of different contributing factors to the LCOS of a VRFB and identify opportunities for cost reduction through operating strategies (e.g., rebalancing schedule), performance improvements (e.g., reducing fade rates), design decisions (e.g., battery sizing), and investment approaches (e.g., electrolyte leasing). We anticipate this analysis will provide new insights into the cost-drivers for VRFBs and motivate further research efforts in understudied yet important areas.