High-performance lithium-ion anodes with hierarchically assembled single-crystal SnO ₂ nanoflake spheres

A large-scale hierarchical assembly route is reported for the formation of SnO ₂ on the nanoscale that contains rigid and robust spheres with irregular channels for rapid access of Li ions into the hierarchically structured interiors. Large volume changes during the process of Li insertion and extraction are accommodated by the SnO ₂ nanoflake spheres' internal porosity. The hierarchical SnO ₂ nanoflake spheres exhibit good lithium storage properties with high capacity and long-lasting performance when used as lithium-ion anodes. A reversible capacity of 517 mA h g ^-1, still greater than the theoretical capacity of graphite (372 mA h g ^-1), after 50 charge-discharge cycles is attained. Meanwhile, the synthesis process is simple, inexpensive, safe, and broadly applicable, providing new avenues for the rational engineering of electrode materials with enhanced conductivity and power. Let it SnO ₍₂₎! A simple template-free hydrothermal method yields hierarchical SnO ₂ nanoflake spheres for high-performance lithium-ion battery anodes. The spheres displayed high reversible capacity of 517 mA h g ^-1 at a rate of 0.2 C after 50 cycles, owing to 1) short diffusive path of electrons and mass, 2) better interconnection between SnO ₂ nanoflakes, 3) large specific surface area, and 4) the good accommodation of volume change.