Review on proton exchange membrane fuel cell stack assembly: Quality evaluation, assembly method, contact behavior and process design

Proton exchange membrane (PEM) fuel cells are ideal power sources with great potential for automobiles, backup power systems and stationary applications, owing to high efficiency, zero emissions and high power density. For these devices with large power consumption, many unit cells are assembled in series to construct a stack to provide the required voltage and power. However, the assembly process remains a major obstacle to the large-scale deployment of high-power stack. The performance and durability of stacks are greatly affected by the assembly procedures, and the impact mechanism and assembly technique need to be fully understanding. This paper presents an overview of important issues related to the assembly process of fuel cell stacks, providing a basis for engineers and researchers to improve stack performance. It begins with a description of quality evaluation of the stack assembly, followed by assembly methods to clarify the history of the development of stack design. The main contributions to in-situ behavior of stack during the assembly compression and dynamic compression is presented in detail. Numerical methods and optimization techniques are analyzed to guide assembly process. Finally, novel stack designs involving the assembly process are sorted out. A summary of the key points in this area is also provided as a direction for future work. The aim of this paper is to evaluate which factors affect the cell performance during assembly process and how adverse effects should be mitigated via mechanism analysis, quality evaluation, assembly method selection, process optimization and novel stack structure design.