Publication date: 27 October 2017

DeadlineModel: single-stage

Planned opening date: 24 January 2019

Deadline: 25 April 2019 17:00:00

Topic Description

Specific Challenge:

Redox flow batteries (RFB) are considered prime candidates for grid-scale stationary energy storage due to their ability to store large amounts of electrical energy for extended periods and release it quickly when needed. Key features include their scalability, independent sizing of energy and power rating, room temperature operation and potential long cycle life. However, currently used RFB rely on redox couples that are non-indigenous to Europe, not widely available and therefore relatively costly. In addition, the voltage and energy density that can be achieved in aqueous flow batteries are constrained by undesired water electrolysis and the low solubility of the active species. This challenge is in line with the identified priorities in the context of the SET-Plan[1].


The objective is to develop and validate RFB based on new redox couples and electrolytes (such as organic or earth-abundant substances) that are environmentally sustainable, have a high energy and power density, maximise lifetime and efficiency, while minimising their cost. Validation of new designs must include testing of full-size prototypes in pilot facilities.

Specific issues to be addressed include:

  • Long-term stability of the redox couples under repetitive voltage swings, and their enhanced solubility and reversibility;

  • Low membrane resistance (or even membrane-free systems);

  • Improved electrode reaction kinetics;

  • Upscaling (especially increasing the reaction surface);

  • Improved battery control systems;

  • Environmental sustainability; and

  • Safety aspects (toxicity, flammability).

Since cost is the most important driver for grid scale electricity storage, targets for key performance indicators such as levelised cost of energy (€/MWh), cost per surface power density (€/Wm-2) and capital cost (€/kWh of capacity) should be set. “Balance of plant” components should be included in cost optimisation.

The activities are expected to bring the technology from TRL 3 to TRL 5 (please see part G of the General Annexes)[2].

The Commission considers that proposals requesting a contribution from the EU of between EUR 3 and 4 million would allow this specific challenge to be addressed appropriately. Nonetheless, this does not preclude submission and selection of proposals requesting other amounts.

Expected Impact:

Project results should contribute to reach the targets set in the SET Plan, putting the energy storage cost on the path to fall below 0.05 €/kWh/cycle by 2030. Overall, the results should stimulate investment in the low-carbon energy sector, with the long term aim to boost innovation-driven growth and industrial competitiveness in stationary electrical energy storage. The proposed action should contribute to accelerating the integration of large shares of intermittent renewables (in particular solar and wind) into the energy system by pushing the boundaries of stationary electrical energy storage.

Cross-cutting Priorities:

Clean Energy


[2]This topic is complementary to topic LC-NMBP-27-2019 (Strengthening EU materials technologies for non-automotive battery storage), which addresses TRL 4 to 6.

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