The energy density of lithium ion batteries heavily relies on the loading of electrochemically active materials in their cathode. LiNi0.8Co0.15Al0.05O2 (NCA) as a promising high-energy cathode material has a practical specific capacity of about 200 mAh g(-1) which, however, is often compromised by the additives in the electrode, such as the conductive carbon and binder. To harvest a higher energy density NCA electrode, cyclic voltammetry and galvanostatic intermittent titration techniques are employed herein to evaluate the apparent chemical diffusion coefficient of Li+ and maximize the loading of NCA. Our results show that the carbon content can be reduced to 0.2 wt% (with 97.8 wt% of NCA), making a high-energy cathode for Li-ion batteries. This protocol would also set a precedent for the energy density optimization of other cathodes.