“…As a refined and elegant material developed by nature, ESMs exhibit a porous structure constituted by proteins that evolved to play crucial roles in the development of the chicken embryo, such as the protection conferred by the crystallization of CaCO 3 and the critical proviso of adequate gas exchange. , From a material science perspective, this hierarchical structure is a fascinating scaffold for the tailoring of functional nanostructures that could benefit from its good mechanical resistance, flexibility, biodegradability, and porosity and exploit the abundant presence of carboxylic, amino, and hydroxyl functional groups to incorporate active materials. , In addition, one of the most attractive sustainable aspects of using ESM residues is the widespread availability of eggshell as a waste material from which a preformed membrane can be easily recuperated, dispensing the use of special resources for its treatment or preparation. Indeed, in recent years, ESM has been considered as a convenient biotemplate to produce self-standing composites for diverse applications, such as sensors, − adsorbents for water remediation, , catalysis, − fuel cells, , and batteries. , Of particular interest to us is their use in SCs as ESM electrodes , and as separators, both in their in natural or modified forms.…”