As a high potential compound, NiCl2 is an ideal anode material for high powder thermal battery, but its small specific surface area and poor conductivity hinder the application in thermal battery. In present study, The Ni-NiCl2 composite with high specific surface area and conductivity was prepared by sublimation and in-situ synthesis, as cathode materials for thermal batteries. The precursor material NiCl2 center dot 6H(2)O was dried to dehydrate and sublimated at 850 similar to 900 degrees C in Ar atmosphere successively. And then the yellow sublimed powder was reduced at 300 similar to 500 degrees C in Ar + H-2 atmosphere for 1 h. Finally, the Ni and NiCl2 composite powders were formed. Thermoanalysis, crystal structure, in-situ synthesis process and electrochemical performance of the powders were analyzed. The results show that NiCl2 crystal grows along the direction perpendicular to c axis and formed a layered structure of 200-300 mu m in the sublimation process. The resistivity of Ni-NiCl2 composite is reduced with the increase of elemental Ni content. The discharge curve of LiSi vertical bar LiCl-LiBr-LiF vertical bar NiCl2 thermal batteries with Ni-NiCl2 (5wt% elemental Ni) as anode material at 1000 mA/cm(2) is more stable and has a shorter activation time, as compared to the discharge curve with pure NiCl2 as anode material.