Affordable High-Performance Green Redox Flow Batteries

Project Information

HIGREEW

Grant agreement ID: 875613

DOI 10.3030/875613

Closed project

EC signature date 21 October 2019

Start date 1 November 2019

End date 31 May 2023

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost € 3 786 747,50

EU contribution € 3 786 747,50

Coordinated by

CENTRO DE INVESTIGACION COOPERATIVA DE ENERGIAS ALTERNATIVAS FUNDACION, CIC ENERGIGUNE FUNDAZIOA
Spain

Periodic Reporting for period 2 - HIGREEW (Affordable High-Performance Green Redox Flow Batteries)

Reporting period: 2020-11-01 to 2022-02-28

Summary of the context and overall objectives of the project

HIGREEW aqueous organic electrolyte-based redox flow battery will be an alternative for large-scale stationary energy storage applications that will be aligned with Europe’s main roadmaps towards climate neutrality by 2050. The EU has defined two cornerstones to achieve a sustainable economy, climate-neutral: The European Green Deal and the SET-Plan (European Strategic Energy Technology Plan).
On one hand, the Green Deal establishes that by 2030 the targets to achieve are:
• At least 40% cuts in greenhouse gas emissions (from 1990 levels)
• At least 32% share for renewable energy
• At least 32.5% improvement in energy efficiency
On the other hand, the SET-Plan defined that by 2030 stationary energy storage must reach 0.05€ /kW/h/cycle, 10.000 cycles, and 20 years of life.

Redox Flow Batteries have emerged as an alternative for stationary storage applications, such as renewables integration due to their ability to store large amounts of electrical energy for extended periods and release it quickly.

The HIGREEW project addresses these challenges to develop a sustainable, low cost, and safe advanced redox flow battery technology:
1. To develop and optimise the aqueous organic electrolyte-membrane-electrode tandem
- A highly stable and sustainable aqueous organic-based electrolyte formulation ensuring high energy density for the battery for its entire lifetime 10.000 cycles and meet cost targets for stationary energy storage. This electrolyte should be based in abundant element and be produced in bulk quantities.
- A stable and low resistance membrane that can operate at high current densities of ≥ 100 mA cm-2 and a cell voltage of 1.0 V.
- Stable 3D carbon electrodes that upon low cost mild activation present high activity (> 10-3 cm s-1) that is not rate limiting in the battery cell.

2. To design, build, test, and validate efficient AORFB cells and stacks
- Designs, prototype cells, and prototype stacks, with suitable values of electrical resistance and current losses to show high voltage and high power, and manufactured for easy disassembly and recycling.

3. HIGREEW prototype engineering and validation in pilot facilities
- Design and prototype of AORFB systems and advance control strategies for high round-trip efficiency, safe long lifecycle and minimum LCOS.

4. Demonstrate the use of AORFB through the integration with renewable energy sources
- Demonstration of the high techno-economic viability of the HIGREEW technology.

5. Ensure the safety and sustainability of the HIGREEW technology
- Define protocols that identify, prevent, and control hazards associated with the battery prototype handling. A further target is to reduce the carbon footprint of RFB to be equal or less than the one of Li-ion batteries.

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

The work of this second period has been mostly focused on targeted objectives 1, 2 and 3: lab research for the development and optimization of the electrolyte and membrane and consultation and discussion for the design of the HIGREEW stacks. Despite some delay caused by the COVID-19 pandemic, and changes in the consortium (one partner withdrawing and another one joining), the project objectives are still within reach.

Activities linked to objectives 4-5 also already started during this second project period, even if the main related tasks will be completed in the third and last project period.

Below a short summary of the results achieved so far for the active WPs:
WP1 (M1-4) Is completed, and objectives achieved (since RP1)

WP2 (M3-32) Tests and selection of active materials and membranes have been performed. Electrolyte-membrane-electrode-bipolar plate solutions that can be upscaled for the HIGREEW prototype and meet the intended cost targets have been defined. In addition, a new generation of high-performance materials has been developed.

WP3 (M11-M43) Detailed characterization and modelling tools have been applied in the definition of the cell and stack design for AORFB. A low-cost stack concept has been developed. Last period will include construction and validation of low electrical resistance stacks for aqueous organic electrolytes.

WP4 (M6-M36) A prototype schematic diagram has been created which represents the key elements of the system from chemical storage and power conversion through to the overall BMS and site layout at La Plana in Spain. Components for the prototype have been selected and evaluated, monitoring protocols for all key variables have been defined and operation conditions and risk evaluation have been defined.

WP7 (M1-43) Dissemination of project results via newsletters, project website, scientific presentation at conferences and publications. Clustering activities with other EU projects.

WP8 (M1-43) General project coordination. Preparation and submission of project Amendment. Update Advisory Board.

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)

HIGREEW methodology to bring the technology from TRL3 to TRL5 started on the materials that mainly influence redox battery performance (electrolyte, membrane, electrode), different strategies have been investigated for their optimisation. At the laboratory scale, after initial structural and electrochemical characterization of components (i.e. NMR, SEM, EIS.) to identify the most promising materials, those have been integrated in single cell set-up. Testing in single cell has confirmed the suitability of this new generation of materials: high cell voltage chemistries, highly selective membranes, low-cost activation protocols for 3D carbon electrodes. Moreover, stability of the components over cycling has been confirmed.

Transition from small devices of 4 cm2 to intermediate set up of 600 cm2 has been done and served for characterization for new designs. Deep characterization of materials for AORFB has been done with the aim of designing cells and stacks for those alternative chemistries. Specific modelling first at the cell level has been developed to better define the electrical and hydraulic processes and will be later upscaled to a multi-cell complete stack. Specific testing of basic functionality will be done before a final completed set of tests for stack validation. Validated new stack design with optimised materials will be integrated into a prototype with all components of the balance of plant. This is planned for the third and last project period.
Physical equipment engineering will result in a real size prototype whose operation has to be controlled. Specific Matlab/Simulink model will be developed for the prototype and the algorithms to implement advanced control strategies in the BMS. The prototype will be tested at La Plana renewable plant (Spain).

HIGREEW major results so far (till M28 of project lifetime):
1) New highly soluble actives species for AORFB that can provide high energy density electrolytes with significant improvement in cell voltage and that can operate at neutral pH.
2) Stable set of electrolyte-membrane-electrode-bipolar plate tandem as a cost-effective solution for AORFB
3) New protocols for membranes and electrodes optimisation to obtain high performing materials and decrease cost of the power module to make RFB more cost competitive.
4) Progresses in stack and prototype design for AORFB identify particular needs of this chemistry for design of the stack and for monitoring and operation of the prototype (temperature, pressure, gas sensors, flow rate, etc.)
5) Preliminary HAZOP study of the prototype for AORFB, identification of risks and safeguards.

Schematics and photography of demonstrator flow cell and validation apparatus