A Self‐Growth Strategy for Simultaneous Modulation of Interlayer Distance and Lyophilicity of Graphene Layers toward Ultrahigh Potassium Storage Performance

Abstract Herein, a simple but effective self‐growth strategy to simultaneously modulate the interlayer distance and lyophilicity of graphene layers, which results in ultrahigh potassium‐storage performances for carbon materials, is reported. This strategy involves the uniform adsorption of individual metal ions on the oxygen‐containing groups on graphene oxide via electrostatic/coordination interactions and in situ self‐conversion reaction between the metal ions and the oxygen‐containing groups to form lyophilic ultrasmall metal oxide nanoparticles modified/intercalated graphene skeleton (OM‐G) with precisely regulated interlayer distance. The synergistic effect of expanded interlayer distance and enhanced lyophilicity is revealed for the first time to significantly reduce the ion diffusion barrier and enhance ion transport kinetics by experimental and theoretical analysis. As a result, such unique OM‐G monolith as free‐standing anode for potassium‐ion battery (PIB) delivered an ultrahigh reversible capability of 496.4 mAh g −1 at 0.1 A g −1 , excellent rate capability (306.6 mAh g −1 at 10 A g −1 ), and remarkable long‐term cycling stability (96.3% capacity retention over 2000 cycles at 1 A g −1 ), which are not only much better than those of previous graphene/carbon materials but also among the best performances for all PIB anodes ever reported. This study provides new fundamental insights for boosting the electrochemical properties of electrode materials.