Effect of Calendering LiFePO₄Electrodes

LiFePO 4 electrodes, composed of 5% PVDF and 5% carbon, were coated on aluminum foil. The LiFePO 4 electrodes were calendered to 2.5 g cm −3 . A comparison of the electrochemical performance of uncalendered and calendered LiFePO 4 electrodes was made. Electrochemical impedance spectroscopy analysis of LiFePO 4 symmetric cells and analysis of four-point probe resistance measurements showed that calendering of the electrodes resulted in a large decrease in contact resistance at the current collector – electrode interface. Rate capability data of Li/LiFePO 4 coin cells showed that calendered electrodes maintained their capacity better than uncalendered electrodes at high rates. The contact resistance, made up of constriction resistance and film resistance, was analyzed with contact theory for plastic deformation.