The dual modification strategy of nitrogen-doped carbon coating with MnO inter-layers helps enhance the stability of...

Silicon (Si) exhibits enormous development potential as an anode material for lithium-ion batteries (LIBs), attributed to its ultra-high theoretical specific capacity and low plateau potential. At present, silicon-based anodes have been widely regarded as the second-generation anode materials for LiBs that may be applied in the future. However, the silicon anode itself has problems such as poor electrical conductivity, severe volume expansion and low cycle life. While carbon (C) encapsulation remains the prevailing strategy for stabilizing silicon anodes, this study introduces an advanced hierarchical architecture. We utilized an in-situ self-polymerization mechanism to grow a manganese oxide interface directly onto the silicon substrate, which was subsequently enveloped by a carbonaceous shell. This dual-modification approach yields a synergistic effect, resulting in significantly enhanced electrochemical performance compared to conventional single-layer coatings. The manganese oxide (MnO) interlayer performs a dual function: it serves as a mechanical buffer to shield the silicon from pulverization and contributes supplementary electrochemical capacity via conversion reactions. Concurrently, the exterior nitrogen-doped carbon (NC) shell exhibits sufficient elasticity to accommodate the severe volumetric fluctuations of the composite during lithiation. This synergistic design effectively averts structural collapse and maintains the integrity of the electrode architecture throughout the cycling process. The surface morphology of the as-prepared material was characterized via Transmission Electron Microscope (TEM). MnO and C were stratified and coated on the surface of Si particles. We designed three different ratios of Si and Mn and explored that when the ratio of Si to Mn was 3:1, the composite material (namely Si@MnO@NC-3) represented the pricise thermodynamic balance between maximun energy density and manximun durability. Si@MnO@NC-3 composites maintained a specific capacity of 1023.19 mAh g^-1 after 1500 cycles at 1 A g^-1 condition. The dual modification theory and method provided by us have the potential to be applied in the future, offering a new idea for the modification of silicon-based anode materials.