Provided is a secondary battery in which high energy density can be obtained
and charging/discharging cycle characteristic can be improved. A positive electrode
(13) and a negative electrode (15) are stacked with a separator (16)
interposed therebetween, and are enclosed inside an exterior can (11) to
which an electrolyte is injected. The negative electrode (15) contains a
negative electrode material capable of occluding/releasing lithium in an ionic
state. Thereby, lithium metal precipitates in the negative electrode (15)
in a state where the open circuit voltage is lower than the overcharge voltage.
In other words, lithium is occluded in an ionic state in a negative electrode material
capable of occluding/releasing lithium in the beginning of charging, and then lithium
metal precipitates on the surface of the negative electrode material thereafter
during charging. The amount of precipitation of lithium metal is preferable to
be from 0.05 to 3.0 times, both inclusive, the ability of charging capacity of
the negative electrode material capable of occluding/releasing lithium. Thereby,
a high energy density and an excellent cycle characteristic can be obtained.
