Novel methods and approaches for supercapacitor separator using waste newspaper

Abstract A sustainable upcycling strategy for fabricating high‐performance supercapacitor separators was established using cellulose fibers derived from waste newspaper. The recycled cellulose substrate was conformally coated with Parylene C via chemical vapor deposition (CVD) to enhance mechanical durability, chemical resistance, and electrochemical functionality while preserving its porous fibrous network. Morphological, chemical, and surface analyses confirmed that the vapor‐phase polymer coating uniformly encapsulated the cellulose fibers without structural collapse, improving inter‐fiber connectivity and surface hydrophobicity. Fourier‐transform infrared spectroscopy verified the coexistence of functional groups from both the cellulose backbone and the Parylene C film, indicating successful surface modification. Electrochemical evaluations demonstrated improved charge storage capacity, reduced internal and interfacial resistances, and enhanced ion transport characteristics compared to a commercial polyethylene separator. These findings underscore the effectiveness of polymeric surface engineering on recycled cellulose substrates in producing environmentally friendly and structurally robust separator membranes, offering a viable route for next‐generation energy storage components by integrating material sustainability with electrochemical reliability.