Review of Potential Step and Potential Sweep Methods In Electrochemical Energy Conversion

This tutorial will focus on the use of potential step methods (chronoamperometry and chronopotentiometry) and potential sweep methods (linear sweep voltammetry and cyclic voltammetry) in the context of electrochemical energy conversion devices, namely fuel cells and electrolyzers. The fundamental principles governing each method will be presented. The use of potential step methods in conjunction with microelectrodes will be discussed in the context of estimating the permeability of reactant gas molecules (such as hydrogen and oxygen) through polymer electrolytes that serve as the central layer in low temperature fuel cells and electrolyzers. Various microelectrode geometries will be discussed and the governing equations (and assumptions involved in obtaining them) presented for each geometry. Microelectrode geometries most suited for the proposed applications will be identified. Following this, the use of potential sweep methods as diagnostics for evaluating gas permeability, catalyst and catalyst support durability, as well as electrode utilization will be outlined. The presentation will conclude with a discussion of how the experimental insights obtained using the above methods are useful in the design of improved materials and architectures.