Hard templating synthesis of mesoporous and nanowire SnO2 lithium battery anode materials

Abstract

Mesoporous and nanowire SnO₂ anode materials for lithium batteries were prepared using KIT-6 and SBA-15 SiO₂ templates, and their electrochemical properties were compared at different current rates. The as-prepared SnO₂nanowires had a diameter of 6 nm and a length of >3 μm and Brunauer–Emmett–Teller (BET) surface area of 80 m² g⁻¹ while mesoporous SnO₂ showed a pore size of 3.8 nm and a BET surface area of 160 m² g⁻¹. The charge capacities of these two anodes were similar to each other at 800 mAh g⁻¹, but mesoporous SnO₂ showed much improved cycle life performance and rate capabilities because of its higher surface area than nanowire SnO₂. Especially, the capacity retention of the mesoporous SnO₂ was 98%, compared with 31% for the SnO₂nanowires at a 10 C rate (= 4000 mA g⁻¹). The improved electrochemical performance of the mesoporous SnO₂ was related to the regular porosity which permitted thorough flooding of the electrolyte between the particles, and the mesopores which acted as a buffer zone during the volume contraction and expansion of Sn.