A Few‐Layer Quasi‐Graphite Anode With Rigid–Flexible Synergy for High‐Performance Potassium‐Ion Batteries

ABSTRACT Potassium‐ion batteries (KIBs) have emerged as promising candidates for grid‐scale energy storage due to abundant K resources and reversible K + de‐/intercalation in graphite (KC 8 , 279 mAh g −1 ). However, practical application is hindered by severe volume expansion (≈60% for K + vs. ≈10% for Li + ), which induces stress accumulation, structural degradation, and capacity fading. Here, we develop a few‐layer quasi‐graphite (QGr) via structural reconstruction of graphite to regulate its mechanical stability and kinetics. The resulting QGr architecture integrates ordered domains with mechanically compliant graphene interfaces, creating a rigid–flexible synergy that alleviates intercalation‐induced stress and lowers the kinetic barrier for K + intercalation. As a result, the QGr anode delivers a reversible capacity of 279.2 mAh g −1 at 0.1 A g −1 and maintains stable cycling over 1200 cycles. Notably, QGr exhibits a pronounced low‐voltage plateau of 246.1 mAh g −1 below 0.5 V. Combined in situ Raman spectroscopy and kinetic analysis demonstrates that K + ‐storage in QGr is dominated by an intercalation mechanism. This work demonstrates that rational structural engineering of graphite can simultaneously regulate structural stability and ion transport kinetics, providing a promising strategy for designing high‐energy KIBs.