A Uniform Self‐Reinforced Organic/Inorganic Hybrid SEI Chelation Strategy on Microscale Silicon Surfaces for Stable‐Cycling Anodes in Lithium‐Ion Batteries

Abstract A promising anode material for Li‐ion batteries, silicon (Si) suffers from volume expansion‐induced pulverization and solid electrolyte interface (SEI) instability. Microscale Si with high tap density and high initial Coulombic efficiency (ICE) has become a more anticipated choice, but it will exacerbate the above issues. In this work, the polymer polyhedral oligomeric silsesquioxane‐lithium bis (allylmalonato) borate (PSLB) is constructed by in situ chelation on microscale Si surfaces via click chemistry. This polymerized nanolayer has an “organic/inorganic hybrid flexible cross‐linking” structure that can accommodate the volume change of Si. Under the stable framework formed by PSLB, a large number of oxide anions on the chain segment preferentially adsorb LiPF 6 and further induce the integration of inorganic‐rich, dense SEI, which improves the mechanical stability of SEI and provides accelerated kinetics for Li + transfer. Therefore, the Si4@PSLB anode exhibits significantly enhanced long‐cycle performance. After 300 cycles at 1 A g −1 , it can still provide a specific capacity of 1083 mAh g −1 . Cathode‐coupled with LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM90) in the full cell retains 80.8% of its capacity after 150 cycles at 0.5 C.