Improved electrochemical performance of binder-free multi-layered silicon/carbon thin film electrode for lithium-ion batteries

The interstratified structure will enable us to probe cycling stability and rate performance of silicon-based thin film electrodes in Li-ion batteries, especially the generation of poorly reproducible and unstable silicon oxide. Carbon films are an effective strategy to conquer this challenge by fabricating silicon/carbon (Si/C) multilayer thin film electrodes. Here, a multi-layered Si/C thin film structure was directly fabricated by magnetron sputtering method without applications of any binders. Carbon-covered Si/C multilayer structural electrode (*C/Si/C/Si/C) attains an initial discharge specific capacity up to 2316.0 mAh g−1 and a high cyclability with retention of 90.1% (1220.9 mAh g−1) after 200 charge/discharge cycles at 0.2C (797.1 mA g−1). The carbon film layer acts as a strong and flexible buffer during cycling process and form a stable SEI, which is beneficial to achieving fast Li+ migration and abating the volume expansion of Si active film. Moreover, the relatively moderate growth temperatures from 100 °C to 300 °C are proved to play a major role to effectively improve the specific capacity of these film electrodes. These results yield fruitful insights into the nanostructured design of a binder-free Si/C-based high cycling performance electrodes via mature magnetron sputtering technology.