Electrochemical device

An electrochemical device dischargeable at −30 degrees centigrade and quickly chargeable at 25 degrees centigrade by repeatedly occluding and releasing lithium ions in a construction in which an organic electrolytic solution is permeated into a wound or stacked electrode group or the electrode group is immersed in the organic electrolytic solution with a separator interposed between a positive electrode having a positive electrode material formed on a surface of a metal foil and a negative electrode having a negative electrode material formed on a surface of a metal foil, wherein:

• a pressure of 0.3 kgf/cm2 to 1.1 kgf/cm2 is applied to a main surface of an electrode group including the positive and negative electrodes,
• the positive electrode material consists of a mixture of lithium-containing compound particles whose surfaces are coated with an amorphous carbon material and a conductive carbon material in which the surface carbon atoms thereof are chemically bonded to one another, or the lithium-containing compound particles and the conductive carbon material are uniformly dispersed and mixed,
• the negative electrode material contains at least one kind of particles selected from among graphite particles having a specific surface area of not less than 5 m2/g and soft carbon particles and the conductive carbon material, in which the graphite particles are coated with an amorphous carbon material and the surface carbon atoms of the graphite particles and those of the conductive carbon material are chemically bonded to one another or the graphite particles and the conductive carbon material are uniformly dispersed and mixed,
• the metal foil has a plurality of through-holes, formed therethrough, each having a projected portion on at least one surface thereof,
• the organic electrolytic solution consists of an organic solvent and a mixed electrolyte dissolved therein and the mixed electrolyte contains lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, and
• the separator is made of at least one selected from among woven cloth, nonwoven cloth, and paper.