A study of Ni^sub 3^S^sub 2^ synthesized by mechanical alloying for Na/Ni^sub 3^S^sub 2^ cell

To synthesize nanocrystalline Ni^sub 3^S^sub 2^ cathode material for Na/Ni^sub 3^S^sub 2^ cell with low cost nickel and sulfur elements, mechanical alloying (MA) was employed directly and with different ball powder ratios (BPRs) of 20: 1, 25: 1 and 30: 1, the mean particle size of 3.99, 2.84 and 2.75 μm can be obtained, respectively. In order to ulteriorly reduce the particle size to improve the contact areas between the active materials, the wet ball milling with the normal Hexane (C^sub 6^H^sub 14^) as the milling solvent was also conducted for 30 h using the ball milling machine, and the submicro Ni^sub 3^S^sub 2^ powder particles can be gained. The charge/discharge properties of Na/Ni^sub 3^S^sub 2^ cells for wet milled system were investigated at room temperature using 1 M NaCF^sub 3^SO3 (sodium trifluoromethanesulfonate) dissolved in TEGDME (tetra ethylene glycol dimethyl ether) as the liquid electrolyte. And the initial charge/discharge capacity was 397 and 425 mAh/g, respectively, which indicates the small particle size of cathode materials are conductive to the discharge properties.[PUBLICATION ABSTRACT]