Electrochemical properties of the NiS powder prepared by co-precipitation method for lithium secondary battery.

We synthesized two nickel sulfide powders by simple method. One is nickel sulfide powder (CNS) by co-precipitation is composed of nano-sized nickel sulfides as NiS and NIS2. The other is nickel sulfide powder (HNS) by heat-treatment of CNS is composed nano-sized NIS. The electrode using CNS has a high first discharge capacity of 600 mA h g(-1) at 0.5 C and the discharge capacity after 20th cycle is 312 mA h g(-1). The electrode using HNS has a high first discharge capacity of 551 mA h g(-1) at 0.5 C and has the discharge capacity of 412 mA h g(-1) after 50th. The discharge rate capability has over 92% at 1 C versus 0.2 C. The nano-sized nickel sulfides are synthesized by simple co-precipitation method has good electrochemical properties such as high first discharge capacity, good cycle life and good rate capability for lithium secondary battery.

Electrically exploded silicon/carbon nanocomposite as anode material for lithium-ion batteries.

In this work, silicon (Si) containing carbon coated core-shell nanostructures were synthesized by electrical explosion of Si wires in ethanol solution followed by high energy mechanical milling (HEMM) process. Material characterization was carried-out using transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. HEMM led to very fine and amorphous Si particles in the presence of carbon and inactive Silicon-Carbide (SiC) matrix. These Si based nanocomposites, obtained through electrical explosion followed by HEMM (milled sample), exhibited enhanced electrochemical performance than unmilled nanocomposites, when evaluated as anode material for lithium-ion batteries (LIBs). On completion of (the) 1st cycle, milled and unmilled sample(s) showed specific discharge capacities around 825 mAh/g and 717 mAh/g, respectively. Interestingly, the coulombic efficiencies of milled and unmilled samples were 98.5% and 97% after 60th cycle respectively. The enhanced electrochemical performance is attributed to fine and amorphous Si based nanocomposite obtained through HEMM process.