CAREER: Membraneless Micro Fuel Cells

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

ABSTRACT PI: Paul Kenis Institution: University of Illinois at Urbana-Champaign Proposal Number: 0547617 Title: CAREER: Membraneless Micro Fuel Cells This laboratory research will exploit some of the characteristic physical properties of the microscale, most notably laminar flow, to obtain membraneless microfluidic fuel cells that the PI and his coworkers recently introduced as a promising power source for portable applications. In these laminar flow-based fuel cells (LFFCs) a fuel containing stream (e.g. methanol, formic acid) and an oxidant containing stream (e.g. dissolved oxygen, permanganate) merge in a single microfluidic channel and proceed to flow laminarly in parallel due to lack of turbulent mixing at these small dimensions. Within this channel, these fuel and oxidant streams flow over and react at, respectively, the anode and cathode that line opposing sidewalls. The absence of a physical barrier eliminates issues such as fuel crossover, water management, and restrictions on media composition that are typically encountered in more common polymer electrolyte membrane (PEM, e.g. Nafion) based fuel cells. The performance of the membraneless LFFCs is dictated by well-understood microscale transport phenomena. Engineering of the mass transfer characteristics of the depletion boundary layers on the electrodes is one of the specific topics of study of this project. This work will focus on exploiting the opportunities of membraneless laminar flow-based fuel cells in the development and performance optimization of alkaline and bio-fuel cells, since the lack of a membrane overcomes many technical issues that to date have severely limited their promise. This will be accomplished as follows: a) Membraneless alkaline fuel cells are to be built that exploit the advantage of superior electrocatalytic activity at both the anode and the cathode in alkaline media while avoiding carbonate formation and membrane clogging issues that to date have hampered the development of PEM-type alkaline fuel cells with few exceptions. b) In membraneless biofuel cells the use of multistream laminar flow enables tailoring of the pH in the individual fuel and oxidant streams to maximize the stability and activity of the individual enzymes, whereas presently biofuel cells are operated using a certain compromise pH. c) Research to optimize the performance and fuel utilization of membraneless fuel cells is planned. Design rules will be derived to capture operation conditions (flow rates, fuel/oxidant flow rate ratio, fuel and oxidant concentrations, etc.) and design parameters (channel length, electrode to electrode distance, etc.) to maximize the performance of an individual LFFC. Introduction of an air-breathing gas diffusion electrode already overcomes mass transfer limitations at the cathode. The introduction of multiple inlets (or outlets) to periodically replenish (or remove) the depleted boundary layer is proposed to address the now arisen anode limitations. Broad Impact The educational component of this CAREER development program will consist of (1) the development of modules for a course entitled Microchemical Systems; (2) a multidisciplinary Microchemical Systems lecture series; (3) a graduate program for the development of non-technical skills. The latter non-technical skills program, the core of the proposed educational program, will consist of four components: (i) a Workshop presenting the fundamentals and importance of non-technical skills, as well as the wide variety of available opportunities to improve those skills; (ii) a Personal Development Plan based on a skills assessment and implementation of that plan with the aid of mentors, typically chosen from alumni of the department; (iii) a Project Management Seminar in which typical situations in a corporate environment are simulated; and (iv) a Lectures Series by prominent alumni in leadership positions. The effectiveness of the program will be assessed by student feedback and third party evaluation. The PI will initiate and coordinate the development of this program and work closely with experts in the field in order to ensure the programs efficacy.