Murilo Leite Alcantara

How can renewable energy be stored more sustainably, while avoiding critical raw materials and reducing the dependence on costly membranes? This was the central question behind MeBattery, Mediated Biphasic Battery, an EIC Pathfinder project funded by Horizon Europe and dedicated to the development of a new generation of redox flow batteries.

Completed in 2025, MeBattery started from an ambitious idea: replacing the conventional physical separation between electrolytes with separation driven by thermodynamics itself. Instead of relying on an ion-selective membrane, the project explored aqueous biphasic systems, ABS, designed to keep redox species in distinct liquid phases and reduce cross-contamination.

At the University of Aveiro, the work was developed by the PATH group, coordinated by Prof. João A. P. Coutinho, with a focus on thermodynamic modelling, selection and characterization of complex liquid systems. Our contribution focused on using COSMO-RS to predict which combinations of salts, ionic liquids and additives could form improved ABS for flow battery applications. This strategy enabled a rational pre-screening of electrolyte systems before experimental validation, reducing trial and error and accelerating the identification of promising candidates.

Beyond modelling, different ABS were experimentally prepared and characterized. The work included the evaluation of redox species partitioning between phases, viscosity, density, stability and electrolyte composition. These data were essential to understand the balance between selectivity, low cross-contamination and physicochemical properties compatible with flow operation.

The project progressed from component and interface studies to the validation of a laboratory-scale demonstrator operated under flowing conditions. The final European Commission review highlighted that MeBattery performed exceptionally well, validated the core principles of the technology at TRL 4, and generated a strong scientific basis for further development. Key outcomes included the identification of selective biphasic systems, the understanding of interfacial processes, the validation of redox mediator, solid active material and biphasic electrolyte combinations, and four patent applications.

MeBattery shows how molecular thermodynamics, electrochemistry and complex liquid systems engineering can open new routes for more sustainable energy storage technologies. The project has ended, but it leaves behind a scientific and technological platform ready for the next stages of optimisation, scale-up and exploitation.

Methanol is one of the key molecules in the energy transition. It can act as a renewable fuel, a chemical energy carrier and a building block for the chemical industry. Yet, its sustainable production from CO₂ remains constrained by a classical chemical engineering problem: the thermodynamics of the reaction itself.

This is the challenge addressed by ILIMITED, First-ever Ionic Liquid sorbent Methanol synthesis In order To Enable over 80% yielD, a Horizon Europe Research and Innovation Action funded under the HORIZON-CL5-2024-D2-01 call and grant agreement No. 101192964. The project runs from 2025 to 2027 and is coordinated by the National Institute of Chemistry, Slovenia, bringing together academic and industrial partners across Europe.

The central idea of ILIMITED is easy to state, but difficult to achieve: selectively remove reaction products, especially methanol and water, using ionic liquids as sorbents, thereby shifting the equilibrium of methanol synthesis from CO₂ and H₂. The project aims to move beyond the current benchmark yield of around 60% and reach yields above 80%, by integrating three technological advances: selective sorption with ionic liquids, catalyst encapsulation to prevent deactivation and undesired direct contact with the liquid phase, and 3D-printed reactors designed to improve heat and mass transfer.

This ambition is especially relevant for decentralised CO₂ sources, such as wastewater treatment plants. In this context, CO₂ from biogas can move from being a residual emission to becoming a local feedstock for e-methanol production. ILIMITED explores this concept as a route for long-term energy storage, renewable fuel production and the valorisation of environmental infrastructures as future biorefineries.

At the University of Aveiro, the work is carried out by the PATH group, coordinated by Prof. João A. P. Coutinho, with a focus on ionic liquid selection, thermodynamic modelling and sustainability assessment of the value chain. Our contribution focuses on the use of COSMO-RS, COSMO-SAC and AI-assisted approaches to predict which ionic liquids offer the best balance between sorption selectivity, thermal stability, low volatility, suitable viscosity and expected performance for methanol and water separation under relevant operating conditions.

In practice, this means turning a vast chemical space, with thousands of possible cation and anion combinations, into a rational shortlist of candidates for synthesis, characterization and testing. Modelling reduces trial and error, guides the experimental preparation of new ionic liquids and supports the selection of sorbents able to improve methanol synthesis efficiency. This connection between molecular thermodynamics, experimental data and statistical learning is one of the key contributions of the Aveiro team to the project.

The work is already generating results. The project has publicly reported the laboratory-scale synthesis of tailored ionic liquids bearing hydrophilic functional groups, while maintaining stability and viscosity as key design criteria for sorbent screening and process development. Selected ionic liquid samples have already been prepared and shipped to consortium partners for testing under relevant operating conditions. In addition, the ILIMITED results page lists University of Aveiro contributions on high-temperature solvent screening for methanol separation, COSMO + AI for solvent screening applied to methanol synthesis, and ionic liquids for high-temperature methanol and water separation.

ILIMITED is still ongoing, but it already points to a clear direction: using molecular modelling and ionic liquids to address one of the fundamental limits of CO₂ conversion into renewable fuels. By connecting computational chemistry, experimental characterization, catalysis, reactor engineering and sustainability, the project seeks to bring decentralised e-methanol synthesis closer to a viable technology for energy storage and carbon valorisation.