Improvement of the cyclability of Li-ion battery cathode using a chemical-modified current collector

An aluminum current collector was treated by simple reacting an aluminum foil with a solution containing three acids, and the physical effect of this modification on surface of current collector was investigated through scanning electron microscopy (SEM) and contact angle test. Charge/discharge cycling test and electrochemical impedance spectroscopy were used for investigating the role of the treated-Al collector in LiNi0.8Co0.15Al0.05O2 cathode electrode. SEM images show that the surface of the collector is roughened by this method. Also, measurements of the contact angle indicate that the tendency of the modified-foil surface to disperse the solvent is greater than the pristine foil surface. Electrochemical impedance spectroscopy reveals the role of rough surface of the collector on the SEI layer resistance and charge-transfer process. The capacity stability of the modified-collector cathode is far more than the pristine-foil cathode during cycling test. Improved electrochemical results can be attributed to an increase in the surface roughness of the collector and a larger surface area, which allows the binder to stick the active material to the surface from more sites and the separation of active materials from the electrode during the cycling process is greatly reduced.