Influences of fabrication processes on electrochemical properties of Si thin film electrodes for Li ion microbatteries

Influences of fabrication processes on electrochemical properties of Si thin film electrodes were investigated by utilizing a Ni buffer layer and annealing the fabricated films. Electrochemical properties of four Si film electrodes (Si/Cu, annealed Si/Cu, Si/Ni/Cu and annealed Si/Ni/Cu) fabricated with different processes were evaluated. Si electrode films fabricated on Cu substrate and Ni film were amorphous and their structures are still maintained after annealing. Fine Ni clusters with a trigonal shape were observed in the Ni/Cu film and coalesced after annealing. The highest capacity efficiency can be obtained from the Li/Si cell with the annealed Si/Ni/Cu film. The insertion of the Ni film as a buffer film and the post-annealing enhanced adhesion between Si film and Cu substrate.