Membrane-free Low cost high Density RFB

Project Information

MELODY

Grant agreement ID: 875524

DOI

10.3030/875524

Project closed

EC signature date 15 November 2019

Start date 1 January 2020

End date 31 October 2024

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost

€ 3 996 612,50

EU contribution

€ 3 987 612,50

Coordinated by

TECHNISCHE UNIVERSITEIT DELFT
Netherlands

Periodic Reporting for period 3 - MELODY (Membrane-free Low cost high Density RFB)

Reporting period: 2023-04-01 to 2024-10-31

Summary of the context and overall objectives of the project

The world’s energy supply is rapidly transitioning from a fossil fuel economy to a renewable resource economy. To enable this transition, we need to deal with intermittent energy production from solar and wind. Electricity storage will be key to allow this renewable energy economy. To be viable and sustainable, it will require both operational costs low enough for an attractive return on investment and access to sufficient materials to produce the necessary volumes. It is critical that storage technology is based on low cost, elementally abundant active materials.
Redox Flow Batteries (RFB) are a key enabling technology for the energy transition. Mass market introduction of RFBs has been hampered by various factors – material scarcity and cost (e.g. vanadium based RBF), limited catalyst lifetime, membrane costs, system complexity and safety issues. The development of an economically viable, environmentally benign and sustainable redox-flow battery (RFB) storage systems is therefore eagerly awaited. MELODY will develop a sustainable RFB technology that is able to reduce the costs of electricity storage to an absolute minimum.
To achieve a breakthrough in inexpensive, large scale energy storage, the MELODY project leverages 3 key elements:
1) A membraneless flow battery concept
2) The use of a widely abundant redox chemistry of hydrogen and bromine
3) A simplified system design
The MELODY project aims to increase the power density of this novel redox flow battery concept to 20 kW/m2, and reduce the price of stored electricity well below 0.05 €/kWh. Ultimately, the reduction of the price for stored electricity means this redox flow battery can be applied at large scale as an electricity storage technology to buffer daily fluctuations in energy supply and demand.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the MELODY project, we have been developing a membraneless redox flow battery system. To achieve that, we develop new materials for electrodes, electrolyte, and a new design of the flow cell. For the electrode materials, we have been developing materials that facilitate the hydrogen reactions and are resilient against Br2. For the electrolyte, we study complexing agents for making the Br2-solution more energy-dense and safer, and what limits we have in charging and discharging the battery. For the cell design, we optimize the resistance and flow of fluids, to obtain a power density of 20 kW/m2.
For all these three aspects (catalysts, complexing agents, cell design), we have developed the technology beyond the state-of-the-art, and having the targets for the end of the project within reach.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The membraneless cell design eliminates the need for expensive membranes. As a bonus, this also lowers the internal resistance. Furthermore, catalyst degradation is avoided due to the elimination of species cross-over, plaguing some conventional designs. The concept of a membraneless design could be applied in a broader field than H2-Br2 redox flow batteries only. Our key research results will be published in scientific journals to exploit this innovation in a broader context. We compare the system as well to a system with optimized membranes (with minimal membrane thickness), which is available for testing at larger scale.
The concept of a single tank design also challenged the separation between liquid (this case HBr/Br2) and gas (this case H2). We have developed separation strategies to allow a single tank design, which could benefit the complexity and costs of other flow batteries as well.
When further unlocking the potential of a membraneless flow battery, including high power density, high energy density and system stability, we bring down the cost of electricity storage in flow batteries well below 0.05 €/kWh. Hydrogen and bromine are abundantly available on a global scale, as water and bromide salts, respectively. The low price, together with the almost unlimited availability of resources for this battery type, allow to scale the H2-Br2 flow battery for large (grid) scale energy storage, and allow an energy transition to fully renewable energy.

MELODY cell design