A high-tortuosity holey graphene in-situ derived from cytomembrane/cytoderm boosts ultrastable potassium storage

The sluggish K⁺ kinetics and structural instability of the generally-used graphite and other carbon-based materials hinder the development of potassium-ion batteries (PIBs) for high-rate capability and long-term cycling. Herein, inspired by the unique flake structure and chemical composition of cytomembrane and cytoderm, we design high-tortuosity holey graphene as a highly efficient anode for PIBs. The flake cytomembrane and cytoderm shrink into wrinkled morphology during drying and sintering and then convert into high-tortuosity graphene after oxidative exfoliating and thermal reducing process. Meanwhile, the proteins, sugars, and glycolipids embedded in cytomembrane and cytoderm can in-situ form nanoholes with highly abundant oxygenic groups and heteroatoms around, which can be easily removed and finally the high-tortuosity holey graphene is obtained after a thermal reducing process. The stress distribution after K⁺ intercalation confirms the optimized release of strain caused by the volume change through the finite element method. Benefiting from the unique nanoholes shortening the ion-diffusion length, the synergy of wrinkled and holey structure stabilizing volume fluctuation, and the enhanced electronic conductivity and specific surface area, the high-tortuosity holey graphene demonstrates high reversible capacities of 410 mAh g^–1 at 25 mA g^–1 after 150 cycles and retains 91.5% at 2 A g^–1 after 2500 cycles.