A cathode composition and a rechargeable electrochemical cell comprising same are disclosed. The cathode composition is described as comprising (i) particles including a transition metal selected from the group consisting of Ni, Fe, Cr, Mn, Co, V, and combinations thereof; (ii) alkali halometallate; (iii) alkali halide; (iv) source of Zn; and (v) source of chalcogenide. Also described is a rechargeable electrochemical cell comprising the composition. The source of Zn and source of chalcogenide in the cathode composition of a cell may be effective to improve the extractable capacity of cells, and decrease the cell resistance, relative to their absence.