Electrolyte Flow Field Variation: A Cell for Testing and Optimization of Membrane Electrode Assembly for Vanadium Redox Flow Batteries

Abstract

A great deal of research has been dedicated to improving the performance of vanadium redox flow battery (VRFB). In this work, we propose the design of a cell for testing membrane electrode assembly of VRFB, which enables the optimization of the flow field, conditions of charge‐discharge tests, and the nature of components (electrodes, membrane) with minimal time and material expenses. The essence of the proposed cell is that the system of channels distributing the electrolyte is made by cutting shaped holes in the sheets of graphite foil (GF). This manner allows easy modification of the flow field configurations. Polarization curves for serpentine, interdigitated, and flow‐through systems were measured according to procedures used in such studies. Cell with GF plates being tested with vanadium‐sulfuric acid electrolyte, outperforms the cell with conventional graphite plates with the same parameters of the flow field. It demonstrates 734 mW cm−2 of peak power density at SOC 50 and 84.3 % of energy efficiency at 84.5 % of electrolyte utilization under galvanostatic charge/discharge cycling with 75 mA cm−2.

Two‐Membrane Acid‐Base Flow Battery with Hydrogen Electrodes for Neutralization‐to‐Electrical Energy Conversion

“…Series of carbon paper electrodes (one of them with Pt/C catalyst layer) is inserted in electrode gaskets. After these gaskets graphite current collectors are followed [concept of redox flow battery (RFB) cell with graphite foil current collectors described in authors’ previous works] [52–55] . Then flow field frames for electrolyte distribution, sealing gaskets, and metal end plates with compression fittings.…”

Fluoropolymer impregnated graphite foil as a bipolar plates of vanadium flow battery

“…The total resistance of the cell, derived from the polarization slope, was lower for the cells based on the GF bipolar plates, comparing to the composite bipolar plate, which was in agreement with previous works. 21,22 Since the specific surface area of the pressed GF is significantly higher than the specific surface area of graphite (the value varies from 17 to 68 m 2 /g for GF different materials, while for natural graphite this value is about 0.6 m 2 /g 30 ), one can assume that the value of the contact resistivity of the GF/porous electrode is slightly less than that for the graphite/electrode contact. As a result, the ohmic resistivity of the cell on the GF was reduced compared to the assembly on the graphite material (Table 1), which led to an increase in the specific power of the RFB from 780 to 860 mW/cm 2 .…”

“…The study of new material for BPs is still an actual question. Earlier our group proposed a new concept of fast-prototyping of RFB MEA individual cells 21,22 or stacks 23 utilizing a series of laser-cut graphite foil (GF) sheets. BPs made of GF with laser-cut channels allow fasting prototyping RFB with various flow field designs to optimize battery efficiency.…”

A Composite Membrane Based on Sulfonated Polystyrene Implanted in a Stretched PTFE Film for Vanadium Flow Batteries

“…[36] Membrane tests in the VRB prototype were performed at a housedesigned cell with 4 cm 2 active area with 3 layers of Sigracet SGL 39AA carbon paper and Serpentine FF channel structure. [37,38] The electrolyte contained 10 ml of 1 M vanadium ions in 4 M sulfuric acid and was pumped with 60 ml/min flow rate. EIS data from V (IV) solutions in both compartments was measured before the test procedure as a control.…”