However, despite the mentioned advantages, both LIBs and PEMFCs face challenges requiring further research and development efforts to optimize their manufacturing processes to attain better performance and efficiency. The redox reaction in a commercial LIB cell occurs at its main components, the positive and the negative electrode, and the final electrochemical performance of an electrode depends on their microstructure, which is highly influenced by the manufacturing process. The manufacturing process includes different stages, the first of them is the slurry preparation, which consists of mixing active material (AM), electron conductive additive, binder, and solvent. This is followed by the slurry coating over the current collector. Then, since this is a wet process, it is followed by the drying step, where the solvent is evaporated to get the dried electrode. Then, the electrode is calendered to improve the contact between the electrode and the current collector and to reduce the overall thickness, which improves the cell energy density. By controlling these manufacturing parameters, like the AM chemistry selected for the slurry preparation or the gap and the speed in the rolls during calendering, we are able to also control the electrode microstructure. Therefore, the effect of these manufacturing parameters on the final electrode properties (density, porosity, mass loading, tortuosity factor) must be well understood to choose the best set of parameters that allow the optimization of the LIB cell performance. For PEMFCs, the Gas Diffusion Layer (GDL) is one of the most important components controlling the electrical and thermal conduction, reactant gases' dispersion and diffusion, and water management, which ultimately affects the PEMFC's performance. The three main stages of the GDL manufacturing involve carbon fiber production, followed by carbon paper substrate preparation and lastly, the finishing treatment. Starting with a wet-spinning step, polyacrylonitrile (PAN)-derived carbon fibers are processed into precursor fibers. These carbon fibers are sized and chopped after stabilization and carbonization. To improve the mechanical stability, conductivity, and reach desired porosity, a step involving the previous carbon fibers, mixed with water and binder, are then subjected to papermaking, bonding, impregnation, curing, and carbonization steps. Finally, the GDL substrate is dipped in polytetrafluoroethylene (PTFE).