The present invention relates to ionic liquids having low melting points, low viscosities and high electrical conductivities; and more specifically, to ionic liquids including at least one organic onium ion and at least one anion represented by the formula: [Z-BF3]−wherein Z is an alkyl group, an alkenyl group, or a fluoroalkenyl group. The ionic liquids according to the invention are capable of easily dissolving electrolytes such as lithium salts, and are also nonflammable and have low viscosities; therefore, the ionic liquids are suitable for use as electrolyte solvents for lithium batteries such as lithium secondary batteries, electric double-layer capacitors, and the like. The ionic liquids according to the invention are suitable for use in electrochemical devices such as lithium secondary batteries, fuel cells, solar batteries, electrical double-layer capacitors and the like; as solvents for chemical reactions; and as lubricants.