The influence of compaction on the porosity and electrochemical properties of LiCoO 2 positive electrodes, in lithium ion batteries, discharged at different rates is studied. The results show that at discharge rate lower than 1C, the capacity increased as electrode density increased. However, at discharge rates greater than 2C, the capacity showed an inverse relation to the density. The indication is that the inter particle contact resistance, which decreases with increase in compaction, is the key factor determining the discharge efficiency at a rate below 1C. However, at discharge rates above 2C, other factors such as conductivity in the liquid phase and contact area between active particles and electrolyte (wettability) would govern the discharge capacity, in addition to the inter-particle contact resistance. A compromise between all the above factors, required for better battery performance, translates to a recommended electrode density between 3.4g/cm 3 and 3.2g/cm 3 .