The effects of the particle size and active materials on the discharge properties of the Li/Fe(X)S2 electrode

Although Li/S batteries produce an efficient initial discharge capacity, they have poor cycle characteristics due to the loss of the active material that occurs in these batteries. Therefore, the material of the metal sulfide series has recently been studied as a substitute. In the present study, the possibility of fine FeS2 and Fe(x)S-2 compound powders (x = Ni, Co, Mo) are examined using a mechanical alloying method, and the discharge capacity is measured. The mean particle size of the FeS2 compound powders was measured to be 600 nm at a milling time of 40 h. This data was attained through the utilization of the SEM morphologies. The initial discharge capacity of a Li/FeS2 battery was 430 mAh/g-FeS2 if into a fine powder for 20 h milled, and 890 mA/g-FeS2 if into a fine powder for 30 h milled. Moreover, it was found that if there is an addition of Ni or Co into the compound, it would increase the discharge properties. Fe(x)S2 composite powders were synthesized in order to improve the cycle life of the battery. From the charge-discharge test results, the initial discharge capacity of the Fe(Ni)S-2 electrode was 845 mAh/g. The initial discharge capacity of the Fe(CO)S-2 electrode was 500 mAh/g, but it showed a better cycle performance than the discharge capacity of electrodes with either additions of Ni or Mo.