New sustainable and recyclable catalytic materials for proton exchange membrane electrolysers

Project Information

RECYCALYSE

Grant agreement ID: 861960

DOI

10.3030/861960

Project closed

EC signature date 12 March 2020

Start date 1 April 2020

End date 30 September 2023

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Advanced materials

Total cost

€ 5 560 727,50

EU contribution

€ 5 560 727,50

Coordinated by

TEKNOLOGISK INSTITUT
Denmark

Periodic Reporting for period 2 - RECYCALYSE (New sustainable and recyclable catalytic materials for proton exchange membrane electrolysers)

Reporting period: 2021-10-01 to 2023-09-30

Summary of the context and overall objectives of the project

RECYCALYSE aims to develop new electrocatalysts for PEM electrolyser systems with increased performance, reduced CRM usage, reduced environmental footprint and reduced total costs. Furthermore, RECYCALYSE will develop processes for large scale recycling of the CRM in order to decrease the dependence on materials imports. Focus will be on new sustainable materials, which are derived from earth abundant elements, and a circular economy will be implemented, in which the CRM that facilitate the electrolysis will be recovered and regenerated. Thus, the project addresses the entire value chain all the way from catalyst manufacturing to system integration and demonstration, to end-of-life recycling, supplying raw materials for the catalyst manufacturing.

The goal of RECYCALYSE is to overcome the main existing barriers for PEM electrolysers to penetrate the market, namely the price, accessibility and performance of electrocatalytic materials. The ambition is that this will result in a significant reduction in the levelised costs of energy storage, leading to improved technical and economic competitiveness of large-scale and low-cost EU energy storage production

The main objectives, the economic/resource objectives and technical key performance indicators (KPIs) needed to realise the vision of RECYCALYSE are listed below. The main objectives are:

MAIN OBJECTIVE 1 Develop and manufacture sustainable new electrocatalysts with improved activity and stability for PEM electrolysis that will reduce or potentially eliminate CRMs, substituting CRM with earth abundant sustainable materials.

MAIN OBJECTIVE 2 Develop a recycling scheme for the PEM catalysts, electrodes and overall system, thus reducing or potentially, avoiding the dependence on materials imports in Europe.

Three families of catalysts will be developed within the project: 1) Supported IrxRuyOz catalysts, 2) catalysts containing lower amount of CRM by alloying with other earth abundant elements (e.g. Ni, Cu), and 3) CRM-free catalysts.

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

At M42, end of the project, the main objectives and milestones have been achieved. Highlights of the results achieved are:

Materials:
Supported catalyst has been developed fulfilling the mass activity KPIs of the project. Oxygen evolution reaction (OER) catalyst active sites have been finetuned by introducing abundant elements such as Ni in the catalyst formulation. This increased the inherent activity of the catalytic sites and together with the activity improvement from the use of catalyst supports, the usage of CRM, Ir and Ru, was reduced by more than 50% in the stack. Catalyst supports were fabricated and utilized to increase the active surface area of the catalysts by preparing small nanoparticles directly onto stable and high conductive supports such as ATO.
CRM-free catalyst of MnOx ahieved 0.3 mA/cm2geo at 1.77 VRHE (H-cell). Mixing MnOx with Au nanowires improved the activity and showed 1.1 mA/cm2 at 1.77 VRHE. This catalyst has shown promising potential, but requires further work, especially for cell integration.

Fabrication:
A flow synthesis method for the production of the supported catalyst materials was developed using water as solvent instead of e.g. ethanol. This brought down the fabrication cost and eased the processing. The upscaled synthesis furthermore reduced water consumption, energy comsumption and processing time by up to 80%.
Single cell MEAs have been prepared from developed supported IrRuNi catalyst, with excellent performance. The increased mass activity of the catalyst structures enabled a reduction in utilized OER catalyst within the membrane electrode assemblies (MEAs) for the final stack to 0.7 mgIr/cm2 and 1 mgCRM/cm2. As Ir is the main cost driver the catalyst material cost is also reduced by more than 50%. Two large batches of MEAs for the stack (14 cells) with this configuration were delivered for PEMEC system integration.

Demonstration:
Two stacks were produced with new catalysts, with reduced CRM usage, and was extensively tested with photovoltaic profiles and accelerated stress tests, achieving efficiencies over 60% under all operation conditions. 14 cells with a surface area of approximately 75 cm2 were produced and assembled, to produce 70 gH2/h at 2 A/cm2. The stack was tested for about 400 hours including photovoltaic profiles, start-stop cycles and accelerated stress tests. No degradation could be measured within this time. The optimized system simulation with balance of plant components for the stack operation achieved above 60% for load point from 5-100% power. LCC showed an initial investment reduction of 33% compared to standard PEMEC, and an indexed LCOH score of 0,8 compared to standard PEMEC.

Circular economy:
Through the developed recycling scheme, utilising a hydrometallurgical approach, a PGM recovery of up to 95% was demonstrated. The recycling steps were adapted to the low concentrations of CRMs taking into account the eco-friendly principles (reducing the energy costs, using the eco-friendly reagents, and recycling the reagents).
An approach for dismantling and further proceeding of PEMEC system was proposed. The separation of valuable parts such as MEA and Ti-flowplates with the help of visual program recognition was demonstrated. The recycling efficiency of the PEMEC system reached 79%. The recycled materials (PGM salts) were reused for the catalyst fabrication reducing the costs and resources of the overall system demonstrated in the LCA.

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 work performed during Recycalyse resulted in a number of improvements towards making PEMECs more efficient, reducing the amount of CRMs and establishing an adequate recycling scheme to close the loop for those CRMs that still need to be utilized.

The intrinsic mass activity of IrO2 was greatly increased by depositing it on a stable and conductive antimony doped tin oxide (ATO) support, while also being alloyed with Ru and small amounts of Ni. The new Recycalyse catalyst showed beyond SoA mass activities and was used to develop membrane electrode assemblies (MEAs) and an activity boost was observed in single cell measurements. The newly developed MEAs were used to produce a stack which showed very good performance and stability, and where the improved mass activity of the anode catalyst allowed for a reduction of CRM usage with more than 50%. Furthermore, the performance was so good that further savings are expected in the future. The developed CRM-free catalyst, based on MnOx, showed beyond SoA catalyst activities, but requires further work, especially regarding cell integration.

A recycling strategy was established which recovers all CRMs from the waste streams. When including not only the end-of-life stack, but also the production waste (e.g. discarded catalyst from synthesis, catalyst sprayed on masks among other components) almost complete recovery is be possible and recycling of the CRMs will decrease the negative social, economic and climate impact due to the lack of mining of these materials.

In conclusion, the Recycalyse project has made significant strides towards achieving its goal of creating a more sustainable and circular approach to hydrogen electrolysis. For future work, it will be important to continue refining the methodology while considering additional impacts to evaluate the resulting sustainability.

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