Nonaqueous-electrolyte secondary battery with a case having heat-welded portions

DETAILED DESCRIPTION In view of the foregoing, an object of the present invention is to sufficiently maintain the sealing characteristics of leads of terminals of electrodes in the heat welding portion of the case without deterioration in the resistance against moisture penetration.
Another object of the present invention to provide a nonaqueous-electrolyte secondary battery exhibiting excellent moisture resistance and long lifetime against charge-discharge cycles.
To achieve the foregoing objects according to one aspect of the present invention, there is provided a nonaqueous-electrolyte secondary battery comprising: a case constituted by laminated film: a battery element accommodated in the case and encapsulated in the case by heat welding,g and leads of terminals of electrodes electrically conducted with the electrodes which are exposed to the outside portion of the case such that the leads are surrounded by heat-welded portions, wherein a portion of at least either of the leads of the terminals of the electrodes corresponding to the heat-welded portion is coated with an olefine adhesive layer containing a titanate coupling material and a coating layer made of resin which is the same as resin which forms the inner most layer of each of the laminated films.
The term "olefine" as used throughout the text of the specification means the same as and is interchangeable with the term "olefin".
As described above, the portions of the leads of the terminals of the electrodes corresponding to the heat-welded portions are coated with the olefine adhesive layer containing the titanate coupling material.
Thus, the adhesiveness of the metal leads of the terminals of the electrodes with respect to the resin can considerably be improved.
The refine adhesive layer is provided for only the portions corresponding to the leads of the terminals of the electrodes.
Therefore, enhancement of the affinity with respect to water occurs in very small regions.
Hence it follows that introduction of water can substantially be prevented