Possibility of Hot-Dipped Aluminum-Coated Steel Sheet as a Current Collector for Lithium-Ion Secondary Batteries

Abstract

For conventional organic electrolytes used in lithium-ion secondary batteries, we evaluated the electrochemical characteristics of hot-dipped aluminum（including 9 mass% silicon）-coated steel sheet, after rolling, as a current collector. Cyclic voltammograms clearly showed coupled redox peaks for potentials of 0-0.25 V（vs. Li/Li^＋）. The redox peaks were attributed to reduction and oxidation reactions corresponding to insertion and extraction reactions of the Li^＋ ion into and from Al and Si. Oxidation current at higher potential was observed from about 3.25 V, indicating an electrochemical window of 3.00 V for potentials of 0.25-3.25 V. Subsequent EDX results revealed that the atomic concentration of Si in the aluminum layer decreased drastically after anodic polarization, suggesting the dissolution of Si. Using hot-dipped aluminum-coated steel sheet, after rolling, as a current collector for a positive electrode was inferred to be difficult. Using Li₄Ti₅O₁₂ and a Li_4.3Ti₅O₁₂ carbon composite for charge-discharge tests, we evaluated the application of a hot-dipped aluminum-coated steel sheet, after rolling, as a current collector for lithium-ion secondary batteries. Results show that the material can be used as a current collector for a Li_4.3Ti₅O₁₂ carbon composite negative electrode.