Dual Engineering of Electronic and Mechanical Properties via Heterocontact-Curvature Interfaces for Ultra-Stable K-Ion Storage.

Abstract

Despite the demonstrated efficacy of contact curvature interfaces in enhancing the electrochemical performance of graphitic carbon materials for potassium-ion batteries, long-term cycling stability remains a critical challenge due to structural degradation caused by repeated volume expansion/contraction. Herein, we propose a structural design by introducing a 3-5 nm ultrathin amorphous carbon buffer layer at the contact curvature interface of graphitic carbon domains, constructing an amorphous/graphitic carbon heterocontact-curvature interface (AG-CI). Through systematic density functional theory calculations, we demonstrate that the AG-CI architecture can significantly enhance the electronic states near the Fermi level, which not only facilitates rapid electron transport but also strengthens reversible K⁺ adsorption at the contact curvature interface. Concurrently, the amorphous carbon buffer layer serves as a mechanical stabilizer, effectively accommodating volume variation during charge-discharge processes, alleviating structural stress, and enabling cycling performance. This synergistic optimization of electronic conductivity and mechanical robustness leads to exceptional electrochemical performance, including rate performance (154.9 mAh g^-1 at 4 A g^-1) and cycling durability (nearly 100% capacity retention per cycle). Our dual engineering strategy, which simultaneously addresses electronic and mechanical challenges, provides a versatile platform for the development of high-performance carbon-based anodes in next-generation batteries.