We have studied the triangular lattice gas model subject to nearest-neighbour repulsive interactions in the mean-field approach, leading to a clear understanding of the order-disorder transition and its effect on the intercalation process in transitional compounds such as LixTiS2. The triangular lattice division into three sublattices enables us to emphasize the appearance and the growth of the ordered phase. The computation of the incremental capacity defined as the response function of the TiS2 cell to the Li+ intercalation allows us to obtain information about the global behaviour of the system with regard to the intercalation process.