2023 Fiscal Year Research-status Report
Prediction of microstructure degradation in SOFC electrodes by unsupervised neural networks
| Project/Area Number |
23K13261
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Sciazko Anna 東京大学, 生産技術研究所, 特任助教 (30898945)
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| Project Period (FY) |
2023-04-01 – 2025-03-31
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| Keywords | Solid Oxide Fuel Cell / Degradation / Machine Learning / Unsupervised learning / Microstructure |
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| Outline of Annual Research Achievements |
Electrochemical devices such as fuel cells, electrolyzers, and batteries undergo microstructural changes during long-term operation, leading to performance deterioration. Predicting these changes is challenging due to incomplete understanding of underlying mechanisms and limited experimental data availability.
In FY2023, a machine learning framework was proposed for predicting microstructure modifications during the reduction process of nickel-based Solid Oxide Fuel Cell (SOFC) anodes. The framework integrates unsupervised neural networks (UNIT) and conditional unsupervised neural networks (C-UNIT). These algorithms were tested on simplified toy problems and for predicting microstructural changes in real SOFC anodes, achieving not only a high visual agreement with real experimental data but also fitting characteristic microstructural parameters.
Moreover, experimental studies were conducted to understand the influence of process conditions on the reduction and oxidation of Ni-yttria stabilized zirconia (YSZ) and Ni-gadolinium doped ceria (GDC) anodes. The investigated conditions included temperature (ranging from 500°C to 1000°C), reduction time, and the number of redox cycles.
The proposed method has the potential to simulate not only microstructural changes during redox cycling but also various degradation processes.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The Ni-YSZ and Ni-GDC SOFC fuel electrodes were successfully fabricated, and redox tests and morphological characterizations were conducted. Machine learning algorithms for the prediction of morphology changes from a limited experimental dataset were developed. The achieved pixel-wise prediction accuracy for the toy problems was over 98%, and good agreement was achieved for the microstructural parameters between real and artificially degraded microstructures.
The feasibility of the conditional C-UNIT algorithm was tested on the reduction of Ni-YSZ anode conducted at different temperatures. The C-UNIT was able to predict various dominant processes depending on the external conditions, resulting in drastic differences in the final microstructures.
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| Strategy for Future Research Activity |
The planned research involves the application of developed machine learning algorithms for the quantitative predictions of SOFC electrode redox processes depending on various external conditions. In particular, it is planned to incorporate the reduction time as a C-UNIT condition, enabling time-dependent predictions. Additionally, it is planned to investigate the effect of the initial sample microstructure on reduction and redox processes. The samples with various microstructures will be prepared by modifying the initial powder composition to influence phase fractions, isostatic pressing of the screen-printed anodes to influence porosity, and increasing the sintering temperature to influence particle size.
In the scope of algorithm development, an extension to physics-informed UNIT (PINN-UNIT) is planned to include physical constraints in the loss function, transforming the black-box machine learning approach into a grey-box model. Additionally, further study on the 3D versions of UNIT, C-UNIT, and PINN-UNIT is currently undergoing research.
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| Causes of Carryover |
The reduced spending in FY2023 is due to the plan of purchase of high performance GPU card shifted to FY2024 as the newer NVIDIA GPU with improved computing capabilities will be released. The usage plan in FY2024 include the purchase of additional GPU card for speeding-up the 3D microstructural calculations.
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