Mesoporous-Si embedded and anchored by hierarchical Sn nano-particles as promising anode for lithium-ion batteries

Si is widely accepted as promising anode material for next-generation lithium-ion batteries due to its large energy storage capability (4200 mA h g⁻¹) and abundant earth reserves. However, its notable volume expansion (over 300%) and low electrical conductivity result in poor cyclic stability. In this work, a mesoporous-Si anchored and embedded by Sn nano-particles (denoted as Sn@MP-Si) has been successfully synthesized by magnesiothermic reduction, impregnation and hydrogenation reduction. The Sn@MP-Si anode delivers a reversible capacity of 1128.6 mA h g⁻¹ after 100 cycles and greatly enhanced rate capability. Even at a current density of 1000 mA g⁻¹, Sn@mesoporous-Si maintains a reversible capacity of 589.7 mA h g⁻¹ after 200 cycles. High-resolution transmission electron microscopy shows that Sn particles around 50–120 nm in diameter are tightly anchored to the surface of mesoporous-Si. Meanwhile, some smaller Sn particles are embedded in the mesoporous-Si pores and intimately contact with Si, which effectively support the pore structure and build a bridge network for electrical conductivity.