Sustainable Power Production in a Membrane-less and Mediator-less Wastewater Microbial Fuel Cell

Microbial fuel cells (MFCs) fed with wastewater are currently considered a feasible strategy for production of renewable electricity at low cost. A membrane-less MFC with biological cathode was built from a compact wastewater treatment reactor. When operated with an external resistance of 250 Ohm, the MFC produced a long-term power of approximately 70 mW/m2 for ten months. Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the cathode biomass when the MFC was closed on a 2100 Ohm external resistance showed that the sequenced bands were affiliated with Firmicutes, -Proteobacteria, -Proteobacteria, -Proteobacteria, and Bacteroidetes groups. When the external resistance was varied between 250 and 2100 Ohm, sustainable resistance decreased from 900 to 750 Ohm, while sustainable power output decreased from 32 to 28 mW/m2. It is likely that these effects were caused by changes in the microbial ecology of anodic and cathodic biomass attached to the electrodes. Results suggest that cathodic biomass enrichment in “electroactive” bacteria may improve MFCs power output in a similar fashion to what has been already observed for anodic biomass

A Comparison of Fick and Maxwell-Stefan Diffusion Formulations in PEMFC Cathode Gas Diffusion Layers

This paper explores the mathematical formulations of Fick and Maxwell-Stefan diffusion in the context of polymer electrolyte membrane fuel cell cathode gas diffusion layers. Formulations of diffusion combined with mass-averaged Darcy flow are considered for three component gases. Fick formulations can be considered as approximations of Maxwell-Stefan in a certain sense. For this application, the formulations can be compared computationally in a simple, one dimensional setting. We observe that the predictions of the formulations are very similar, despite their seemingly different structure. Analytic insight is given to the result. In addition, it is seen that for both formulations, diffusion laws are small perturbations from bulk flow. The work is also intended as a reference to multi-component gas diffusion formulations in the fuel cell setting.Comment: 12 pages, submitted to the Journal of Power Source

MULTI-SPECIES MULTI-PHYSICS MODELING AND VALIDATION OF HYDRODYNAMIC ELECTROCHEMICAL SYSTEM FOR USED NUCLEAR FUEL

Department of Nuclear EngineeringAccurate predictions of processes in hydrodynamic electrochemical systems require an understanding of both the surface electrochemical reactions and the bulk mass transport. Complete coupling of electrochemistry and fluid mechanics is computationally very rich for multidimensional modeling since it involves multiple components across multi-phases at the same time. Therefore, this study develops a computational model that combines a 3D model for calculating single-species mass transport and a 2D model for calculating multi-species electrochemical reactions. The computational model is validated against lab-scale experimental data using a rotating cylinder solid metal cathode and liquid metal anode in the Argonne National Laboratory. The 3D model assumes that U, the representative component in the system, dominates the hydrodynamic behavior, and thus calculates mass transport caused by the rotating solid cylinder electrode. The 2D model still reflects the diffusion of U, Pu, and Nd within a diffusion boundary layer and the bulk concentration changes of these components. The 3D model provides a diffusion layer thickness reflecting convective mass transfer effects to the 2D model. The results of the proposed model show good agreement with the reference experiment, and the model can be considered an important tool for investigating the multidimensional distributions of hydrodynamic and electrochemical variables.clos

Water management system and an electrolytic cell therefor Patent

Description of electrical equipment and system for purification of waste water by producing silver ions for bacterial contro

Improved structural stability of Ni-rich cathode materials via simple dry process for Li-ion Batteries

Department of Energy Engineering (Battery Science and Technology)I reported that highly stable LiNi0.8Co0.1Mn0.1O2 (that is, NCM) via a simple and one-step dry surface treatment approach (that is, G-NCM). The cobalt precursor was coated on the surface of the bare NCM in purpose to improve the material integrity by protecting the cathode surface against the acidic species attack. Furthermore, the transition metal (TM) concentration gradient in the primary particles ensured the structural stability by suppressing the evolution of micro-crack in the cathode particles and reducing transition metal dissolution. The more important thing was the enhanced material integrity allowed stable and uniform solid electrolyte interphase (SEI) layer on the graphite anode, leading to unprecedented full-cell performance. After the surface treatment, the high temperature (45 oC) cycle performance was improved from 20 % for bare NCM to 50 % for G-NCM. During the cycle, the G-NCM retained higher average coulombic efficiency of ~99.8 % than that of the bare NCM (~98.5 %). The electrochemical performance was prepared by full-cell. This finding could be a breakthrough for the LIB technology, providing a rational approach for the development of advanced cathode materials.ope