Electrochemically induced high ion and electron conductive interlayer in porous multilayer Si film anode with enhanced lithium storage properties

Si has been regarded as one of the most promising anodes for next-generation lithium ion batteries for its high theoretical capacity (3579 mA h g(-1)) and low operating potential of 0.4 V vs Li/Li+. However, the huge volume change during (de)lithiation and low electronic conductivity impede its further commercial applications. In this work, Zn/Si porous multi-layer films with controllable layer number (from 1 to 6 layers) are constructed firstly, and then a ZnO thin layer is sputtered on the top surface of the Zn/Si films to fabricate the Zn/Si/ZnO porous multi-layer films. When used as binder-free anodes, the designed 4 layers Zn/Si/ZnO thin film anode delivers the highest specific capacity, best cycling and rate performance than other multi-layer film anodes and the bulk Zn/Si/ZnO film anode with the same overall thickness. The excellent electrochemical properties of the prepared 4 layers Zn/Si/ZnO porous composite film anode can be attributed to its porous and multilayer structure, which can moderate the volume change, decrease the internal stress and benefit to the penetration of electrolyte. Moreover, the 3D electron and Li+ ion conductive channels resulted from the formed Li-Zn alloy during cycling can help to increase the electrochemical reaction kinetics.

Automated summary

By constructing Zn/Si/ZnO porous multi-layer film anodes, the specific capacity and cycling performance of lithium ion batteries have been significantly improved, thanks to the design of porous and multilayer structure and the formation of 3D conductive channels from Li-Zn alloy during cycling.