Abstract
One of the most important parameters for the design of redox flow batteries is a uniform distribution of the electrolyte solution over the complete electrode area. The performance of redox flow batteries is usually investigated by general measurements of the cell in systematic experimental studies such as galvanostatic charge-discharge cycling. Local inhomogeneity within the electrode cannot be locally-resolved. In this study a printed circuit board (PCB) with a segmented current collector was integrated into a 40 cm2 all-vanadium redox flow battery to analyze the locally-resolved current density distribution of the graphite felt electrode. Current density distribution during charging and discharging of the redox flow battery indicated different limiting influences. The local current density in redox flow batteries mainly depends on the transport of the electrolyte solution. Due to this correlation, the electrolyte flow in the porous electrode can be visualized. A PCB electrode can easily be integrated into the flow battery and can be scaled to nearly any size of the electrode area. The carbon coating of the PCB enables direct contact to the corrosive electrolyte, whereby the sensitivity of the measurement method is increased compared to state-of-the-art methods.
Highlights
As an increasing percentage of energy is produced from renewable energy sources, electrochemical energy storage devices are in increasing demand, in order to integrate it into the electric power supply [1].One of the most promising systems to store and to provide electric energy in grid-scale is the redox flow battery [2]
This study presents a novel advanced measurement setup with a segmented electrode on a printed circuit board for locally-resolved current density measurement in all-vanadium redox flow batteries
In this study a novel measuring method with a printed circuit board operating as a segmented current collector for 40 cm2 laboratory-scale all-vanadium redox flow batteries was developed
Summary
As an increasing percentage of energy is produced from renewable energy sources, electrochemical energy storage devices are in increasing demand, in order to integrate it into the electric power supply [1]. Clement et al measure the current density distribution in a square 9 cm all-vanadium redox flow battery with a segmented electrode on a printed circuit board [16]. Bhattarai et al fear that lateral current spread due to uneven local resistances in the electrode of the test cell dominates the current density distribution [23] For this reason, they use open circuit voltage distribution mapping and SOC mapping to analyze the electrolyte flow in redox flow batteries [25,26]. This study presents a novel advanced measurement setup with a segmented electrode on a printed circuit board for locally-resolved current density measurement in all-vanadium redox flow batteries. Different limitation during were visualized and, addition, locally-resolved measurement methods, theeffects printed circuitoperation board electrode increased theinsensitivity the electrolyte flow in the test cell was investigated. Redox flow battery, enabling the reaction path of V3+ oxidation in the positive half-cell to be visualized
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