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NANO2021-Nanoteknologi og nye materiale

Novel molten carbonate/ceramic composite materials for sustainable energy technologies with CO2 capture and utilization

Awarded: NOK 7.0 mill.

Fuel cell based on molten carbonates electrolyte (MCFC) operates at temperatures above 550 °C with advantages such as high tolerance of fuel, high efficiency and low fabrication cost as compared to the other fuel cell types. MOCO3 project work on improving the cathode performance of MCFC by new materials and architectures. When molten carbonates infiltrated into an oxide ion or electronic conducting solid matrix, the composite can serve as CO2 separation membrane at intermediate temperatures. In MOCO3 project one objective is to enhance the performance for such type of membrane by improve the functional properties of solid matrix. New ceramic support materials were screened with respect to their wettability and chemical stability towards molten carbonates. The best candidates were used in asymmetric CO2 separation membrane and oxygen electrode for MCFC. State-of-the-art CO2 flux have been confirmed by measuring 5 samples with similar performance. However, as compared to symmetric membrane architecture, the asymmetric membrane shows significantly decreased stability due to the reduced membrane thickness and leakage caused by gradually wetting of the support by molten carbonates. The properties of the molten carbonates itself with different ions addition was studied and improvement of the transport properties was observed. Composite cathode developed in the project has improved the fuel cell maximum power density more than 50% as compared to the reference NiO electrode at temperature of 550 °C which is conventionally used. New architectures of cathode using NiO were also studied resulting 10% improvement of the maximum cell power density. Numeric modelling on the influence of electrode architecture to the cell performance was established. Validation of the model was made by its fitting to the experimental results. The developed model allows to predict the whole cell performance with varying the microstructure of the electrode. Electrode kinetics studies on an oxide ion conducting matrix supported electrolyte were performed. The limiting step for the reaction was identified which provide us a fundamental understanding of the electrode reactions. The project outcome has high impact to the MCFC technology. The promising results obtained in MOCO3 for the MCFC can significantly increase the power output of the current commercial MCFC systems or reduce the footprint of the system for the same power output. The stability of the electrode must be tested for years in the real operation conditions before implementing to the commercial system. Therefore, new studies on the stability of the newly developed electrode materials are called for.

MOCO3 has 5 partners from 3 countries providing the competence in different areas that are crucial for the project. Close collaboration between the partners results in high performance materials and new concept been developed and validated, respectively. The new electrode materials improve the molten carbonate fuel cell (MCFC) performance and can potentially be used in commercial cells. Asymmetric CO2 separation membrane was produced in the project showing state-of-the-art flux. Some of these results have been published as articles in peer reviewed journals and presentations in international conferences.

The MOCO3 project addresses the Topic 4: Functional Materials. It focuses on the development of novel composite materials consisting of molten carbonates infiltrated in a solid matrix as functional materials in intermediate temperature fuel cells and CO2 selective membranes. These processes enable CO2 separation and/or utilization with possibility for additional power production in CO2 emitter plants of various scales. MOCO3 addresses performance and lifetime of these systems by focusing on materials engineering at all length scales (atomistic, micro- and macroscopic) guided by a synergetic combination of experimental research and advanced numerical simulations for driving materials design. The pioneering work in MOCO3 will establish fundamental understanding of molten salts interaction with solid and gas phases to determine principles governing liquid-solid-gas interactions and distribution of molten carbonates as a function of materials composition, fabrication and operation parameters. Identification and parameterization of mechanisms underpinning materials stability will be sought for reducing melt evaporation and reactivity between materials. The project focusses on developing novel composite materials with optimised transport properties by tailoring the conductivity of charged species (carbonates ions, electrons, oxide ions and hydroxide ions) in each phase and at their interfaces. To this end, solid matrices with functionalized surfaces and interfaces will be produced using green manufacturing routes. The latter will offer possibility for generating coarse or fine porous ceramics with defined pore shape, size, volume and tortuosity. Furthermore, the project will address the fundamentals of surface and electrode kinetics of the composite materials. This work will be supported by high resolution characterisation methods including high temperature diffraction, spectroscopy and microscopy, 3D nano- and micro-tomography.

Funding scheme:

NANO2021-Nanoteknologi og nye materiale