Effective Encapsulated Strategy throughout Lithiation/Delithiation: Enabling a Stable Interface and Fast Kinetics of Silicon Anode for High-Performance Lithium-Ion Half/Full Batteries

Despite the ultrahigh theoretical capacity of silicon (Si), the large volume changes and low intrinsic electrical conductivity lead to inadequate cycle life and poor rate performance, hindering its commercial application. This work smartly used polydopamine-assisted deposition of SnO2 on nano-Si in a hydrothermal environment, obtaining the nitrogen-doped carbon (NC) and SnO2 quantum dot hybrid-encapsulated Si@NC@SnO2 core–shell nanospheres. The core–shell Si@NC@SnO2 demonstrated effective tolerance to the volume expansion of nano-Si due to the protective effect of the organic/inorganic hybrid shell, thereby maintaining its structural and interfacial stability. Furthermore, combined research from ex situ spectroscopy, physical fields, and DFT calculations reveals that the hybrid shell in the Si@NC@SnO2 anode mainly turns into SnO and Li2O after lithiation, avoiding the failed encapsulated strategy caused by Sn coarsening during alloy-step SnO2 reaction. The lithiated shell even stabilizes the electrode/electrolyte interface and facilitates charge carrier transport. Consequently, the Si@NC@SnO2 anode exhibited a reversible capacity of 1056 mAh g–1 after 200 cycles at 0.3 A g–1 and a high rate capacity of 510.7 mAh g–1 at 2 A g–1. Moreover, the full battery retained a capacity of 527.5 mAh g–1 after 100 cycles at 0.3 A g–1. This work focused on an effective encapsulated strategy throughout the lithiation/delithiation processes and achieved a stable interface and excellent cycling performance of the Si anode, thereby providing insights for the commercialization of Si-based anodes in long-life lithium-ion batteries.