The electronic structures of LiNiO2, LiAlO2 and LiNi0.5Al0.5O2 are investigated using density-functional theory (DFT) in the local-density approximation (LDA). The effect of lithium intercalation and the influence of aluminium doping on the structure and electrochemical properties of LiNiO2 are discussed. An increase in the open circuit voltage is observed with Al doping in LiNi0.5Al0.5O2 compound.