LiNi0.8Co0.15Al0.05O2–carbon composite positive electrodes were prepared by the spark-plasma-sintering (SPS) treatment. The SPS treated acetylene black (AB) powder (HDAB) was used as carbon sources, and it showed an effect to improve the electrical connections between the carbon particles. By the SPS treatment of the LiNi0.8Co0.15Al0.05O2 +HDAB blended powder, the strong bindings between the active materials and the carbon powders were formed. Both contact effects, particularly the active material–carbon contact effect, improved the electrochemical performances of the cells. The improvement effects were more evident when the cells were cycled at higher current density, which indicates that the present method is effective to improve the rate capability of the positive electrodes without lowering electrode density.