Abstract: A rechargeable electrochemical device comprising a cathode (6) composed chiefly of activated carbon, anode (3) composed of a lithium alloy, and an electrolyte composed of an organic solvent in which a lithium salt is dissolved. Lithium content in the lithium alloy forming the anode (3) is selected such that, if converted to the electric capacity under the charged condition, the capacity of this alloy ranges from 3 to 20 times the cathode capacity that is obtained when the cathode is discharged from 3.0V to 2.0V in a single-pole potential with respect to metal lithium. This constitution is able to provide a reliable rechargeable electrochemical device, which is proof against super-discharge and excellent in charge and discharge cycle life.