Bulk-Like SnO₂-Fe₂O₃@Carbon Composite as a High-Performance Anode for Lithium Ion Batteries

Boosted power handling and the reduced charging duration of Li ion cells critically rests with ionic/electronic mobility. Ion mobility in electrochemically relevant grains normally stands for an essential restriction of the velocity at which the energy of a cell can be stored/released. To offset sluggish solid-state ionic transport and achieve a superior power/energy density rating, electroactive grains often need exquisite nanoscaling, harming crucial virtues on volumetric packing density, tractability, sustainability, durability, and cost. Unlike elaborate nanostructuring, here we describe that a SnO₂-Fe₂O₃@carbon composite-which adopts a metal oxide particles-intercalated bulk-like configuration-can insert many Li⁺ ions at elevated speeds, despite its micro-dimensionality. Analysis of charge transport kinetics in this tailor-made architecture unveils both much improved ion travel through compact monolithic substances and the greatly enhanced ion access to surfaces of SnO₂/Fe₂O₃ grains. According to the well-studied battery degradation mechanism, it is that both the effective stress management and internal electric field in our as-prepared sample that result in recommendable capacity, rate behavior, and cyclic lifespan (exhibiting a high reversible capacity of 927 mAh g^-1 at 0.2 A g^-1 with a capacity retention of 95.1% after 100 cycles and an ultra-stable capacity of 429 mAh g^-1 even over 1800 cycles at 3 A g^-1). Unique materials and working rationale which ensure the swift (de)lithiation of such micrometer-dimensional monoliths may open a door for various high-power/density usages.