Nickel sulfide cathode in combination with an ionic liquid-based electrolyte for rechargeable lithium batteries

Nickel sulfides, pure Ni(3)S(2) and a mixture of Ni(7)S(6)-NiS, were synthesized through a solvothermal process. The nickel sulfide powders were characterized by X-ray diffraction, scanning electron microscopy, and electrochemical testing. The results showed that the capacity of NiS-Ni(7)S(6) is much higher than that of Ni(3)S(2), when used as the cathode in a lithium cell with an organic solvent-based electrolyte, 1 M lithium bis (trifluoromethanesulfonyl)amide (LiNTf(2)) in poly(ethylene glycol) dimethyl ether 500. The NiS-Ni(7)S(6) electrodes were also tested with an ionic liquid electrolyte consisting of 1 M LiNTf(2) in N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)amide ([C(3)mpyr][NTf(2)]) to compare with organic-solvent based electrolytes. The results revealed that the ionic liquid is a useful solvent for use with this cathode material. (C) 2008 Elsevier B.V. All rights reserved.