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

摘要

State-of-the-art carbon coatings are sought to protect high-capacity siliconanodes, which suffer from low conductivity, large volume change and fastdegradation. However, this approach falls short when handlingphysical–electrical disconnections between carbon shells and siliconmicroparticulate (SiMP) with drastic size variations. Here, a strategy ofcovalent coating is developed to establish a robust encapsulation structure.The obtained covalent Si–C bonds enable an effectively dynamic connectionbetween the electrochemically deforming SiMP and the sliding graphenelayers, preventing the evolution of gaps between SiMP and the carbon shelland maintaining persistent electrical connections as well as mechanicaltoughness. As a result of high structure reversibility, the cycling stability ofthick SiMP anodes is greatly improved, up to a high areal capacity of 5.6 mAhcm~（?2） and volumetric capacity of 2564 mAh cm~（?3）. This interface bondingeffect demonstrates the great potential for suppressing deformation involveddegradation of high-capacity materials through coating strategies.