Inhibition of Al/Cu Contact Corrosion in Lithium Ion Batteries

Nowadays, the safety of lithium ion batteries (LIBs) has attracted considerable attention. Therefore, battery components have been studied rigorously in a way to reduce safety problems such as explosion and fire accidents [1]. A key component in LIBs is the current collector which ensures electronic conduction between the electrode materials and the external circuit. Metallic Al which is widely used as the current collector material for the positive electrode in LIBs [2,3] might be subjected to contact corrosion, when connected to Cu, during the charge and discharge cycles. Such phenomena can shorten the lifetime and compromise the safety of LIBs. This paper will discuss the corrosion behavior of various coatings on Al in contact with metallic Cu. The coatings Ni, Cu and NHP (Nickel High Phosphorus with about 10%P) were studied as corrosion protection coatings for Al current collector. The anodic behavior of the three coatings on aluminum substrates in an organic carbonate based electrolyte were investigated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM). CV data showed that already after the second cycle Cu and NHP exhibited very low current densities and good passivation behavior. Results analysis in Tafel coordinates also demonstrated better corrosion behavior for Cu and NHP samples expressed by a shift of the corrosion potentials to more anodic values. At the same time their corrosion rate values are lower. EIS data showed no considerable variation with the polarization potential especially in the high frequency range. Moreover, in the Nyquist representation the EIS data take approximately the shape of a straight line, suggesting that the charge transfer resistance Rct is large and no corrosion takes place in the potential region [3.6V-4.2V]. References [1] B. Scrosati, J. Garche, J. Power Sources 195 (2010) 2419. [2] C. Iwakura, Y. Fukumoto, H. Inoue, S. Ohashi, S. Kobayashi, H. Tada, M. Abe, J. Power Sources 68 (1997) 301. [3] A.H. Whitehead, M. Schreiber, J. Electrochem. Soc. 152 (11) (2005) A2105.