Modeling and Design of Electrochemical Systems

Richard D. Braatz, Edmund C. Seebauer, and Richard C. Alkire 

Edited by Richard C. Alkire, Dieter M. Kolb, Jacek Lipkowski and Philip N. Ross Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31419-5 

Electrochemical phenomena play a central role in the fabrication and the functional capabilities of a great many materials, processes and devices. A common feature of these systems is that their behavior is largely determined as a result of concerted interactions that extend over many length scales. During the past several decades, the electrochemical field has advanced rapidly based primarily on a suite of remarkable new tools that provide the ability to create precisely characterized 

---

To study the stresses in the system, it is first necessary to calculate the temperature distributions of the SOFC stack. Owing to the coupled nature of the SOFC multi-physics, the temperatures in the stack wiU affect both the electrochemical performance and the mechanical stresses of the stack [49]. The electrochemical performance of the SOFC is coupled to the temperature through the Nernst equation [Eq. (26.11)]. Stack-level models are often used to consider the temperature distributions and how the operating conditions and design of the stack affect the temperatures [1, 48, 49]. In these models, the energy conservation equation [Eq. (26.7)] is solved in the gas and sohd phases, and includes the effects of convection in the fuel and air charmels, radiation between the soHd tri-layer and the gas, radiation between the stack and its surroundings, conduction through the tri-layer, and heat sources due to chemical and electrochemical reactions [1, 50]. The balance... 

However, to move these KMC modeling tools from the hands of experts to a more general audience, there needs to be a more concerted and focused effort in software development. Many of the scientific contributions mentioned in this review are based on individual efforts that rely on in-house codes. The impact of these efforts could be expanded if some flexible, benchmarked codes were readily available. Unfortunately, the variety of electrochemical systems encountered creates limits to simple transferability. Finally, as DFT-based parameter estimation becomes more robust and cost-effective, and as additional KMC simulations of electrochemical systems are demonstrated, we expect that KMC will play an important role in connecting atomistic-level information to experimentally observable phenomena, aiding in the design of many next-generation electrochemical devices. 

Fig. 3. Diagrams of electrochemical cells used in flow systems for thin film deposition by EC-ALE. A) First small thin layer flow cell (modeled after electrochemical liquid chromatography detectors). A gasket defined the area where the deposition was performed, and solutions were pumped in and out though the top plate. Reproduced by permission from ref. [ 110]. B) H-cell design where the samples were suspended in the solutions, and solutions were filled and drained from below. Reproduced by permission from ref. [111]. C) Larger thin layer flow cell. This is very similar to that shown in 3A, except that the deposition area is larger and laminar flow is easier to develop because of the solution inlet and outlet designs. In addition, the opposite wall of the cell is a piece of ITO, used as the auxiliary electrode. It is transparent so the deposit can be monitored visually, and it provides an excellent current distribution. The reference electrode is incorporated right in the cell, as well. Adapted from ref. [113],...

---