(163c) Fabrication of Nanoscale High-Order Hierarchical Sn / C Composites for Highly Reversible Li+ Ion Storage

The rapid progress in portable electronic devices in this information-rich era demands continuing improvement in the performance of the power sources, which are typically the lithium-ion batteries. One of general strategies is to reduce the active electrode materials to the nanoscale to increase the capacity and rate capability of the electrodes. This is a report of our recent studies on the fabrication of various high-order Sn-carbon composites as lithium-ion storage compounds for the anode of lithium-ion battery. They range from hollow core-shell mesospheres, to hierarchical Rambutan-like and chestnut-like nanostructures. The methods of preparation are remarkably simple, environment-friendly, low cost and easily scaled up for volume production. In particular, the chestnut-like nanocomposites fabricated directly on copper current collectors are binder-free and conducting-additive free. Their double roughness structure of nanohairs on mesospheres also impart to them superhydrophobic properties mimetic of the lotus effect. For the unique hierarchical Rambutan-like nanostructure, tin remains electrochemically active even after 200 cycles of charge and discharge, thereby allaying some of the previous concerns on the use of tin as a lithium storage compound. These high-order nanomaterials also show impressively high capacity, high rate capability, and high reversibility demonstrating their potential as carbon alternatives for the next generation lithium ion batteries. This presentation will focus on the synthesis methods and the possible mechanisms of the formation of these intriguing morphologies.