1.  Field of the Invention
The present invention relates to a nonaqueous electrolyte battery. 
2.  Description of the Related Art
Nowadays, a lithium ion secondary battery is expected to be used in applications requiring large current characteristics, i.e., to be mounted on, for example, vehicles such as an electric vehicle (EV) and a hybrid electric vehicle (HEV) or to be used as a large power storage. 
Where the lithium ion secondary battery is used in the field exemplified above, higher safety is required in the secondary battery.  What should be noted in this connection is that a combustible organic solvent is used for preparing the nonaqueous electrolyte that is used nowadays in the lithium ion secondary battery.  So that, it is difficult to improve the safety of such lithium ion secondary battery.  Such being the situation, an ionic liquid, which is an ionic fused material that is in the form of a liquid at room temperature, has attracted attention as a noncombustible nonaqueous electrolyte, as disclosed in, for example, Jpn.  Pat.  Appln.  KOKAI Publication No.  2004-165131. 
However, the ionic liquid has in general an electrical conductivity lower than that of the organic solvent and, thus, is poor in the large current characteristics.