Hollow Triple-Layer Puff-like HCs@Si@C Composites with High Structural Stability for High-Performance Lithium-Ion Battery

Silicon anode materials with ultrahigh theoretic capacity of 4200 mAh g^–1 exhibit an attractive prospect for lithium-ion batteries (LIBs). However, notably volume change (>300%) in the silicon lattice during lithiation/delithiation processes and poor conductivity vastly restrict its commercial applications. Thus, a unique “hollow triple-layer puff” structure with double elastic carbon buffer layers is innovatively designed and prepared by a facile combined technique of a layer-by-layer in situ assembly and reduction process. This hierarchical double-shelled structure with large inner space creates a highly conductive network, affiliating contacts between silicon and double carbon shells for effective charge transfer, as well as configures a stabilized mechanical structure in the process of lithiation/delithiation. The dual-protection effect of double shells endows the electrode with ultralong cycle life, retaining a reversible specific capacity of 1216.8 mAh g^–1 at 420 mA g^–1 over 500 cycles. Moreover, the full cell of HCs@Si@C//LiFePO₄@C exhibits good rate capability and obtains a high energy density of 317.8 Wh kg^–1. The design strategy of the hollow triple-layer puff structure offers a novel path for practical design of multifarious electrode material systems in energy storage or related fields.