Analysis of Electrochemical Reactions on Irregular Pores Structures Relevant to Batteries and Fuel Cells Electrodes

Porous electrodes are important in the applications of fuel cells and batteries by increasing reaction surface area. Systematic understanding of the effect of different pore structures of electro-catalyzed reactions will improve electrode efficiency and, in general, optimize the design of   electrochemical processes occurring in fuel cell and batteries. Electrode systems are analyzed by using models to obtain useful system’s information. This information helps in predicting system level behaviors and assessing experimental results relevant to the design and operation of these pore-based systems. The present work uses analytical models to analyze zero order and first order electrochemical reactions occurring in irregular pore structures applicable for fuel cells and batteries. The electrochemical processes at the electrode pores are modeled by employing the microscopic species mass conservation equation with diffusion in the pore domain and electrochemical reactions present at the boundaries. The microscopic equation is scaled up to the macroscopic pore level by employing an area averaging-based approach to obtain a system level information applicable to practical systems. The area averaged solutions are verified by comparing them with exact solutions based on separation of variables for the ideal cases. Results obtained from the macroscopic equation identified potential deviations in the predicted concentration profiles as the deviation from ideal domains increases. The results predict an important role of the pore geometry on effecting the overall system efficiency as well as the convergence of the averaged solution to the exact solution. This study suggests useful guidelines for modelling and experimentation of complex systems.