Ion- and Electron-Conductive Buffering Layer-Modified Si Film for Use as a High-Rate Long-Term Lithium-Ion Battery Anode.

The rational design of electrochemically and mechanically stable Si anodes is of great importance for the development of high energy density lithium-ion batteries. In this study, patterned Si-based (Si/ZnO/C) trilayer composite films were synthesized by magnetron sputtering with the assistance of a patterned mask. The electron-conductive C layer at the top of the composite film is deposited to enhance the interfacial stability between active film and electrolyte. The ion- and electron-conductive Li2 O-Zn middle layer can be ingeniously introduced by means of the poor reversed conversion reaction between ZnO and Li+ ions after the first cycle. The resultant Si/Li2 O-Zn/C trilayer composite film delivers a high reversible capacity of 1536 mAh g-1 after 800 cycles at a current density of 1.0 A g-1 and a long high-rate cycling stability (1400 mAh g-1 after 6000 cycles even at a high current density of 10.0 A g-1 ). Excellent rate capability and improved Coulombic efficiency are also achieved. The influences of the patterned structure and each modified layer on the electrochemical properties are analyzed systematically. This work offers a new and promising direction to enhance the lithium-storage properties of Si-based thin-film anodes.