Film-clad battery and method of producing a film-clad battery

Abstract

A joint section where covering films 2 a , 2 b of film-covered battery 1 are heat-sealed together is formed with flat surface 6′ having thickness t 1 and groove 6 having thickness t 2 . Groove 6 serves to reduce the projection area of film-covered battery 1 by folding side 2 c toward receiving section 2 a 1 with groove 6 serving as an edge, and groove 6 is made thinner than flat surface 6 ′ by Δt=t 1 -t 2 . Therefore, the length of covering films 2 a , 2 b produced on outer side 6 a is shortened as compared with the case of folding the portion that has thickness t 1 .

1 . A fabrication method of a film-covered battery which has a battery element encapsulated within a covering film having at least one folded joint section formed around said battery element, said method characterized by comprising the steps of:
 forming at least one fold thinner than the thickness of said joint section therearound in said joint section; and   folding said joint section along said fold.   
     
     
         2 . The fabrication method of a film-covered battery according to  claim 1 , comprising the step of forming said fold by pressing at least one side of said joint section with a member having a protrusion. 
     
     
         3 . The fabrication method of a film-covered battery according to  claim 2 , comprising the step of heat-sealing and joining said joint section of said covering film having a heat-sealing property by heating and pressing said joint section with said member. 
     
     
         4 . The fabrication method of a film-covered battery according to  claim 1 , comprising the step of preparing one of a chemical battery and a capacitor as said battery element.