Covalent Coating of Micro‐Sized Silicon With Dynamically Bonded Graphene Layers Toward Stably Cycled Lithium Storage

Abstract

AbstractState‐of‐the‐art carbon coatings are sought to protect high‐capacity silicon anodes, which suffer from low conductivity, large volume change and fast degradation. However, this approach falls short when handling physical–electrical disconnections between carbon shells and silicon microparticulate (SiMP) with drastic size variations. Here, a strategy of covalent coating is developed to establish a robust encapsulation structure. The obtained covalent SiC bonds enable an effectively dynamic connection between the electrochemically deforming SiMP and the sliding graphene layers, preventing the evolution of gaps between SiMP and the carbon shell and maintaining persistent electrical connections as well as mechanical toughness. As a result of high structure reversibility, the cycling stability of thick SiMP anodes is greatly improved, up to a high areal capacity of 5.6 mAh cm−2 and volumetric capacity of 2564 mAh cm−3. This interface bonding effect demonstrates the great potential for suppressing deformation involved degradation of high‐capacity materials through coating strategies.