A combined in situ monitoring approach for half cell state of charge and state of health of vanadium redox flow batteries

Bundesministerium für Wirtschaft und Energi

Creating a design tool for tubular redox flow battery stacks

Stack production costs for electrochemical energy conversion can be reduced by tubular cell designs which enable the extrusion production of cell components and require smaller sealing lengths. In this study we consider the all vanadium redox flow system for the demonstration of the feasibility and the competitiveness of the approach. Starting from single cell studies, we report on recent progress in experimental characterization and model based design in the development of tubular stacks.Bundesministerium für Wirtschaft und KlimaschutzAlternativeReviewe

Long term multi-observable measurements for SOC/SOH analysis and crossover modelling

The operation of vanadium redox-flow batteries (VRFB) is accompanied by electrolyte crossover through the membrane which can lead to selfdischarge and electrolyte imbalances. These imbalances lead to capacity losses, which decrease the state of health (SOH) of the battery. In commercial VRFB systems the state of charge (SOC) of the battery is typically monitored either by coulomb counting, via an open circuit potential or by a combination of both. With these methods electrolyte imbalances cannot be detected. For a reliable imbalance detection, half-cell specific SOCs are needed. Several SOC/SOH monitoring methods have been developed, which are mostly based on one or two measured quantities. We aim for the development of a stable SOC/SOH monitoring method including crossover effects based on the measurement of several SOC/SOH related observables. To establish a long term data basis for the corresponding analysis we perform correlated and partially redundant in situ measurements in a 500h charge/discharge cycling test. In the next step, a comprehensive SOC and SOH model accompanied by an empiric VRFB crossover model shall be developed.Bundesministerium für Wirtschaft und KlimaschutzAlternativeReviewe

Correlating observables for state of charge and state of health monitoring and crossover modelling of vanadium redox flow batteries

Bundesministerium für Wirtschaft und EnergieUnknow

Parametrization and validation of a tool for the electrical design of tubular redox flow stacks

All-vanadium redox flow batteries (VRFB) with a tubular cell geometry offer advantages over the common planar design: improved stability, reduced sealing lengths, cost-saving potentials through production of the components by (co-)extrusion and a more flexible electric cell-setup, possibly reducing shunt currents. In prior works a tubular cell design for VRFBs was developed and further improved by our research group. To transfer the single cell performance to industrial levels, a design tool for stacks suited to the tubular cell geometry is necessary. We report on the progress of parametrisation and validation of the design tool.Bundesministerium für Bildung und ForschungAlternativeReviewe