All-Cellulose-based flexible Zinc-Ion battery enabled by waste pomelo peel

Aqueous zinc-ion batteries are attracting extensive attention due to the long-term service life and credible safety as well as the superior price performance between the low cost of manufacture and high energy density. The fabrication of inexpensive, high-performance flexible solid-state zinc-ion batteries, thus, are urgently need for the blooming wearable electronics. Herein, as a proof-of-concept study of waste into wealth, cellulose flakes derived from waste pomelo peel are utilized as the substrate for electrodes and hydrogel electrolytes into a flexible rocking-chair zinc-ion battery. The unique sandwich-type structure holding the flake-like cellulose substrate and linear carbon nanotubes endows the flexible cathode and anode with fast ion and electron transportation. The obtained cellulose-based hydrogel electrolytes on account of special affinity with aqueous ZnSO₄ electrolyte output an excellent ionic conductivity. The assembled flexible rocking-chair zinc-ion battery benefitting from the synergistic effect of sandwich-type electrodes and cellulose-based hydrogel electrolytes demonstrates outstanding electrochemical performance and mechanical properties. This work not only puts up an effective roadmap for flexible battery devices, but also reveals the great potential of waste biomass materials in energy storage applications.