High-Loading Nano-SnO₂ Encapsulated in situ in Three-Dimensional Rigid Porous Carbon for Superior Lithium-Ion Batteries

Tin oxide nanoparticles (SnO₂ NPs) have been encapsulated in situ in a three-dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m² g^-1), and the SnO₂ NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium-ion batteries, a SnO₂@OMC composite material can deliver an initial charge capacity of 943 mAh g^-1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g^-1, even exhibit a capacity of 503 mA h g^-1 after 100 cycles at 160 mA g^-1. In situ encapsulation of the SnO₂ NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO₂ particles (SnO₂/OMC). The significantly improved electrochemical performance of the SnO₂@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium-ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO₂ NPs.