Structural cathodes: Navigating the challenges in fabrication and multifunctional performance analysis

Multifunctional structural batteries have gained interest in recent years due to their capability to simultaneously store electrochemical energy and bear mechanical load. The structural cathode is an integral component to form multifunctional structural batteries, and its electrochemical and mechanical performance are highly dependent on the fabrication process. Thus, this review aims to explore the fabrication techniques for these cathodes via indirect (casting, dip coating and layer-by-layer assembly, electrophoretic deposition, vacuum filtration & use of polymer matrix) and direct (synthesis) methods. Challenges and improvements in fabricating structural cathodes specific to these techniques will also be put forth, and the influence of cathode microstructure on the electrochemical and mechanical performances will also be discussed. This review also aims to introduce a performance metric using multifunctional efficiency as a basis for comparison when evaluating the multifunctional performance of structural cathodes. Future considerations on improving energy storage and load-bearing capability of structural cathodes will also be highlighted in order to develop more robust and efficient structural batteries.