Si film electrodes adopting a dual thermal effect of metal-induced crystallization (MIC) and Kirkendall effect

Abstract

The structural and electrochemical properties of Si film electrodes with Ni/Ti films on a Cu current collector (Si electrodes) were investigated after annealing in a temperature range of 400-600 degrees C. Metal-induced crystallization (MIC) and Kirkendall effects were simultaneously observed in the Si electrodes annealed above 450 degrees C for 2 h. The MIC effect led to the partial formation of strongly < 111 >-oriented Si in the Si film, and the crystallinity of Si increased with increasing annealing temperature. The Kirkendall effect led to the diffusion of Cu and formed a Cu3Si layer on the surface of the Si film. The capacity of the Si electrodes decreased owing to the formation of the silicide and the efficiency was improved with increasing annealing temperature. A Si electrode annealed at 500 degrees C for 2 h exhibited good cycle performance with an activation region owing to the anisotropic lithiation during the initial cycles and the Cu3Si layers supporting the Si film. (C) 2019 Elsevier B.V. All rights reserved.