Study on the thermal treatment conditions for fabricating open-cell structure Cu-Sn alloy foams

Abstract

Cu-Sn alloy foams, with an open-cell structure, were fabricated by Cu/Sn coelectrodeposition onto a polyurethane (PU) template in an alkaline electrolyte with a citrate complexing agent before undergoing a subsequent thermal treatment for PU removal in a N-2 gas environment. These foams were predominantly comprised of a Cu matrix along with Cu6Sn5 and Cu3Sn intermetallic compounds, which are known as active materials in Cu-Sn alloy electrodes used in rechargeable batteries. The chemical phase change of Cu-Sn alloy foams and its influence on the electrical resistance were studied according to the heating temperature and N-2 gas flow rate. Assuming the thermal degradation of PU as a first-order reaction, the dependence of the PU removal process on the heating temperature was also theoretically investigated. In addition, a postannealing process of the Cu-Sn alloy foams was employed to reduce their electrical resistance by promoting grain growth. (C) 2020 Elsevier B.V. All rights reserved.