Discovery of lithium in copper current collectors used in batteries

Aging studies of Li-ion batteries have been concentrated on degradation of cathode, anode and electrolyte materials with very limited attention to degradation in current collectors. Our data shows the presence of lithium beyond the active material and in the copper current collector (CCC). The lithium impurity in the CCC will lead to degradation in its thermal and electrical behavior and thus cannot be ignored for overall efforts in understanding the aging mechanisms predicting the life and performance of the batteries.