Annealing effect on electrochemical properties of patterned Si film electrodes for thin-film batteries

Abstract Patterned Si film electrodes with trench structured Cu current collector were fabricated by using a facile approach. Ribbon-like Si films were embedded in the trench with 28 μm in trench height. The structural and electrochemical characteristics of the patterned electrodes were investigated after annealing at 200, 300 and 400 °C. For the as-deposited Si film, the Si film consisted of Si clusters at the bottom of trenches. With increasing annealing temperature, the Cu3Si phase was formed at 300 °C and came to the surface of the film electrode through boundaries of Si clusters, and then the coarsened Cu3Si phase covered the Si clusters at 400 °C. The best electrochemical performance was obtained from the 400 °C-annealed Si film electrode due to synergy effects of the formations of the Cu3Si layer and trench structure, which could suppress the Si volume change during repeated electrochemical reactions.