Investigation of electrochemical properties of bio-inspired SiOx/PI multilayered thin film anode for lithium ion batteries

The organic-inorganic multilayer thin film composed of SiOx (nonstoichiometric silicon suboxides) and PI (polyimide) has been synthesized by a hybrid sputtering system combining reactive RF sputtering and pulsed laser deposition. SiOx/PI thin films were deposited on a copper foil to investigate its electrochemical properties. The chemical composition of as-deposited SiOx/PI coatings was measured by a FE-EPMA. The overall multilayered structure was observed by a Scanning Electron Microscopy. The SiOx/PI multilayer thin film anode with proper architecture control exhibits higher columbic efficiency during 1st charge/discharge cycle and better capacity retention as compared to pure SiOx thin film anode. The fracture toughness of SiOx/PI multilayer thin film anode is measured via nanoindentation and be compared to the pure SiOx thin film anode. The results show that the multilayer structure reveals a higher fracture toughness, which leads to a better structure stability during the charge/discharge cycling.