Effects of Electrode Thickness on Three-Dimensional NiCrAl Metal Foam Cathode for Lithium Ion Battery

LiFePO4 electrodes using three dimensional NiCrAl alloy metal foam of different electrode thickness are prepared. In order to improve the electrochemical and cycle-life performance of lithium ion batteries, it is important to optimize the electrode thickness and mass loading of active material. As compared to those with thick electrode, the cells with thin electrode exhibit high rate performance and cycle-life behavior, due to the shorter diffusion length of lithium-ion and improved kinetic behavior. Also, cyclic voltammetry curves and electrochemical impedance spectroscopy analysis indicate that the redox reaction for the thinner electrode occurs much faster, and the charge transfer resistance is much lower. The results of same current density (mA cm⁻²) show that 450 μm-thickness electrode exhibits superior electrochemical and power performance. It is because the 300 μm-thickness electrode which has the lowest mass loading of active material meant that it carried the highest current rate, and thicker electrodes show higher internal resistance and much poorer kinetic property. Namely, electrode thickness and an amount of active material are difference according to the intended use.