Physics-Based Electrochemical Model of Vanadium Redox Flow Battery for Low-Temperature Applications

Vanadium redox flow batteries (VRFBs) operate effectively over the temperature range of 10 & DEG;C to 40 & DEG;C. However, their performance is significantly compromised at low operating temperatures, which may happen in cold climatic conditions. The loss of performance can be attributed to reduced kinetics and decreased diffusivity of ions in the electrolyte. In this paper, we present a physics-based electrochemical model of a vanadium redox flow battery that allows temperature-related corrections to be incorporated at a fundamental level, thereby extending its prediction capability to low temperatures. The model follows the conventional evaluation of the cell overpotential as the sum of contributions from overpotentials associated with activation, ionic conduction and mass transfer polarization. New data-driven models have been proposed to make these sub-models temperature sensitive. The overall model has been validated with a wide range of data from VRFB cells of sizes up to 900 cm(2) and operating temperatures down to -10 & DEG;C. The model results indicate that enhancement of electrochemical performance of VRFB below subzero temperatures requires electrode and membrane activation and improvement in ionic conductivity of the electrolyte.