High Capacity Lithium Ion Battery Anodes Using Sn Nanowires Encapsulated Al₂O₃ Tubes in Carbon Matrix

Tin (Sn) is one of the promising anode candidates for next generation applications in lithium ion batteries with high energy densities, but it suffers from drastic volume change (about 260%) upon lithiation. To address this issue, herein an efficient method is reported for coating Sn nanowires with an amorphous Al₂O₃ layer (Sn-Al₂O₃) based on a combination of mechanical pressure injection technique and partial dissolution of the anodic aluminum oxide template. Further, the Sn nanowires coated with Al₂O₃ are dispersed into carbon matrix (Sn-Al₂O₃-C) by ball milling. In this structure, Al₂O₃ helps to maintain structural integrity during charge-discharge process, and the introduced carbon matrix enhances electronic conductivity of the overall electrode. As a result, the Sn-Al₂O₃-C nanocomposite exhibits an enhanced cyclic and rate performance, namely, retaining the capacities of 1308.8 mAh g^-1 at the current density of 30 mA g^-1 after 20 cycles, 1063.3 mAh g^-1 at the current density of 200 mA g^-1, and 834.2 mAh g^-1 at the current density of 500 mA g^-1 after 100 cycles.