Simulation of all-vanadium redox flow batteries based on COMSOL

In the current situation of energy shortage and environmental deterioration, all vanadium redox flow battery is the most promising new energy storage battery, playing a key role on popularization of distributed power grid and new energy power generation. Following the rigorous mathematical process and the mechanism of VRFB, a VRFB numerical simulation model is established based on COMSOL according to principles of VRFB, the Nernst equation and the electrodynamics. The effects of electrolyte concentration distribution, electrolyte flow rate, electrode compression and electrode temperature on cell performance are studied through the model. The research shows that the vanadium ions will gather to the membrane side and The gradient of vanadium ions concentration near the membrane side is smaller, indicating that the reaction mainly concentrated on the membrane side; The excessive flow rate of electrolyte is too fast for oxidation-reduction reaction, which will reduce cell performance; When the electrode thickness is compressed from 0.36 mm to 2 mm by electrode compression, the terminal voltage drop is 13mV, mainly due to the decrease of ohmic loss; In the allowable range, the battery performance is enhanced with the increasing of the electrode temperature. The model provides an important reference value for the optimization of material properties, geometric parameters and operating conditions.

1 Introduction

Flow battery energy storage technology is a large scale and efficient electrochemical energy storage technology. Compared to other energy storage technology, the flow battery energy storage battery has following advantages: flexible design of output power and capacity; high energy efficiency (>75%); long battery life; high stability and reliability [1]–[2]. Besides the advantages of flow battery, the use of the same element in both half-cells avoids problems of cross-contamination during long-term running [3]. These features make the VRFB have a broad application prospect in renewable energy power system, Peak shaving, EPS and military fields.