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

摘要

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.Mean-while,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.