Abstract: A lithium-ion rechargeable cell is described which contains an electrolyte comprising a pyrazolium cation, an imidazolium cation, or a combination thereof, as well as lithium ion, and at least one non-Lewis acid derived counter-ion and which has a ratio of cathode capacity to anode capacity of 1 or less, 1 or greater, and preferably about 1.3 or greater. Electrochemical cells containing an anode, a cathode, and the ionic liquid electrolytes preferably have effective charge/discharge capacity and charging efficiency at low temperatures and at high temperatures.

Abstract: A lithium-ion rechargeable cell is described which contains an electrolyte comprising a pyrazolium cation, an imidazolium cation, or a combination thereof, as well as lithium ion, and at least one non-Lewis acid derived counter-ion. Electrochemical cells containing an anode, a cathode, and the ionic liquid electrolytes preferably have effective charge/discharge capacity and charging efficiency at low temperatures and at high temperatures.

Abstract: An electrolyte, such as for a lithium rechargeable cell, is described which contains a pyrazolium cation and may also contain a lithium salt. The lithium salt may be at least one of LiBF4, LiAsF6, LiPF6, and LiTF. The electrolyte, when used in an electrochemical cell, has a charge/discharge capacity and charging efficiency that is superior to the same properties of ionic liquid electrolytes without a pyrazolium cation. Electrochemical cells are also described and contain an anode, a cathode, and the pyrazolium cation electrolyte.

Abstract: Low temperature molten salt compositions comprised of a mixture of a metal halide, such as but not limited to aluminum trichloride, and a fluoropyrazolium salt, such as but not limited to 1,2-dimethyl-4-fluoropyrazolium chloride, which are resistant towards oxidation over a wide temperature gradient and are useful as electrolytes in electrochemical cells.