1.Solid oxide fuel cell electrode microstructure reconstruction and analysis
2.Solid oxide fuel cell single cell and stack scale configuration and design by numerical modeling
3.Testing of solid oxide fuel cells with different alternative fuels
4.Hybrid Zn-air/metal batteries for high energy efficiency and high energy capacity
Prof. Meng Ni, Hong Kong Polytechnic University
1.Solid oxide fuel cells (SOFCs) are promising electrochemical energy converters. They are fuel flexible and suitable for combined heat and power cogeneration. The microstructure of solid oxide fuel cells are reconstructed numerically by dropping spherical particles into computational domain. Kinetic Monte Carlo (KMC) simulations are performed to investigate the microstructure evolution in the sintering stage for SOFC fabrication. The important parameters, such as the triple-phase boundary (TPB) length, the tortuosity factor and the porosity are computed at different sintering temperature and sintering times. An optimal sintering time is found which can yield the highest TPB length.
Subsequently, the reconstruction techniques have been extended to reconstruct the nano-structured SOFC electrodes by a 3-step method: (1) the backbone is generated by random packing of spherical particles within a domain which is discretized into pixels with a 5-nm resolution; (2) the nanosized particles are coated on the backbone surface randomly one-by-one; and (3) the infiltrated particles are enlarged to a designed size to simulate the sintering process. The TPB length, percolation behaviors of the reconstructed SOFC electrodes are studied in detail. The study offers insights in properties of the SOFC electrode microstructres.
2.The flow field and stack configuration designs of SOFC significantly influence the SOFC performance. In this talk, multiphysics models are developed to simulate the SOFC cell and stack performance by integrating the electrochemical/chemical processes with heat and mass transfer. The model is applied to simulate SOFC with all porous structure-with porous electrolyte and SOFC with metal foam. It is found that all porous SOFC can achieve good carbon resistance but the performance is sacrificed. It is also found that metal foam is promising for use in SOFC stack to provide uniform gas distribution and good current collection, although the pressure loss with the metal foam is higher. The multiphysics models are powerful tool for SOFC cell and stack design.
3.Solid oxide fuel cells (SOFCs) are promising energy conversion devices due to their high efficiency, low pollution, quiet operation, and fuel flexibility. In this talk, our preliminary experimental study on SOFC using alternative fuels, including methane, biogas, solid carbon, and plastic waste are presented. When solid carbon is used as a fuel, the SOFC performance can be enhanced by using water for carbon gasification, instead of using carbon dioxide for carbon gasification. A 1kW SOFC system is tested using methane as a fuel. The results demonstrate the great potential of SOFC for efficient energy conversion.
4.Effective energy storage is the key to realize wide application of fluctuating and intermittent renewable energy technologies. Zinc-air batteries are promising electrochemical energy storage devices due to their low cost, safe operation and higher energy density than lithium-ion batteries. To improve the discharge voltage of the Zn-air batteries, hybrid Zn-air batteries have been recently developed at The Hong Kong Polytechnic University. This talk will summarize the recent developments in Zn-air batteries in Hong Kong, including the Zn-Co3O4/air batteries and Zn-Ag/air batteries to achieve both high discharge voltage and high energy capacity.
Prof. Meng Ni was born in Meishan, Sichuan, China. He received his PhD from University of Hong Kong (HKU) in 2007 and received the Young Scientist Award in the same year. After working as a post-doctoral fellow at HKU, he joined The Hong Kong Polytechnic University in July 2009 as an Assistant Professor. He was promoted to an Associate Professor in July 2012 and then a Professor and Associate Head in July 2016. Prof. Ni is a Humboldt Fellow and conducted collaborative research in 2017 at the Julich Research Center for 6 months. His research focuses on solid oxide fuel cells and metal-air batteries for energy conversion and storage. His current H-index is 37. Prof. Ni is a frequent reviewer for over 60 journals including Science and Nature Communications. He was the former Associate Editor for Science Bulletin (2015-2017). He is currently an Associate Editor for Sustainable Energy Technologies and Assessments (Elsevier). He received the Top Reviewers Award from Applied Energy in 2010 and the Best Associate Editor Awards from Science Bulletin in 2016 and 2017.