Designing Sandwich Structured Cu/SnCu/Cu Film and Its Use As Negative Electrode for Lithium Ion Batteries

Abstract

We demonstrate the design and the fabrication of Cu/SnCu/Cu sandwich-like structured film by electrochemical deposition method. The Cu layer at the current collector/electrode interface increases the adhesion of the film. And the Cu layer at the electrode/electrolyte interface is believed to hold the electrode together to prevent the delamination and promotes a stable interface formation to optimize the electrochemical performance of the electrode. Moreover, Cu atoms in the SnCu layer of the Cu/SnCu/Cu sandwich-like film serve as conductive pathways to support an effictive lithiation/delithiation reactions between Sn and Li, plus act as buffer to tolerate the mechanical stress induced in the galvanostatic test. Herein it is important to note that possible intermetallics formation between Cu and Si might enhance the reversibility of the lithiation reaction of Sn with Li. Therefore to promote the intermetallic formation in the film, a heat treatment (200˚C, 48h under vacuum atmosphere) has been applied. The galvanostatic test result shows that a remarkable improvement is noted when heat treated Cu/SnCu/Cu film is used as anode.