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, l 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. © 2008 Elsevier B.V. All rights reserved.