Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-03-22
2004-02-10
Chaney, Carol (Department: 1745)
Metal working
Method of mechanical manufacture
Electrical device making
C429S162000, C429S185000, C029S623100
Reexamination Certificate
active
06689177
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P2000-081578 filed Mar. 23, 2000, which application is incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
The present invention relates to a lithium ion battery such as a lithium ion polymer secondary battery having a gel-type or plastic macromolecular electrolyte layer, and a method of manufacturing the same.
In recent years, accompanying by a situation that portable small electric equipment such as small, lightweight cellular phones or portable computers has been popularized, second batteries having small, reliable output characteristics and capable of longtime use by recharging many times such as nickel-cadmium batteries, nickel-hydrogen batteries and lithium ion batteries has been studied and developed vastly as an electric source for supplying electric power to drive the electric equipment.
Among the secondary batteries, the lithium ion secondary battery has characteristics capable of outputting stable electric power despite its small, lightweight, thin in size, and has studied and developed for the purpose of employing as a foldable secondary battery by taking advantage of suitable structural characteristics for its thin size.
Further, as technique capable of achieving the above-mentioned thin size and foldable shape, and of gaining superior characteristics free of leakage unlike the case of employing liquid electrolyte as a dry cell, it is suggested that a technique employs gel-type electrolyte including plasticizer realizing flexibility, and a technique employs macromolecular solid electrolyte, in which a lithium salt is dissolved in a macromolecular material.
In such lithium ion secondary batteries with a thin structure, generally, the main part of the battery is formed in the following manner. A laminating structure is formed by laminating a positive electrode, a positive electrode active material layer, a gel-type macromolecular solid electrolyte layer, a separator, a negative electrode, a negative electrode active material layer. A positive electrode lead and a negative lead electrode joints to the corresponding electrodes in the laminating structure. After this, the laminating structure is covered with package members made of aluminum/polypropylene•laminate pack material, and sealed ends.
As for materials used for the above-mentioned schematic structure, for instance, materials described later can be preferably used. Plastic materials employed here are shortened hereinafter: polyethylene terephthalate; PET, fused polypropylene; PP, cast polypropylene; CPP, polyethylene; PE, low-density polyethylene; LDPE, high-density polyethylene; HDPE, linear low-density polyethylene; LLDPE, nyron; Ny. Additionally, aluminum, which is a metal material employed as a barrier film having moisture permeability resistance, is shorten as AL.
The most typical structure is a combination such that a package member, a metal film and a sealant layer are respectively PET, AL, and PE. Other typical laminating structures can be also employed as the same as this combination. Such combinations are: PET/AL/CPP, PET/AL/PET/CPP, PET/Ny/AL/CPP, PET/Ny/AL/Ny/CPP, PET/Ny/AL/Ny/PE, Ny/PE/AL/LLDPE, PET/PE/AL/PET/LDPE, or PET/Ny/AL/LDPE/CPP.
As for materials employed as the sealant layer of a laminating film, the above-exemplified PE, LDPE, HDPE, LLDPE, PP, and CPP and the like can be employed, and its thickness is preferably in a range of 20 &mgr;m~100 &mgr;m based on the observed results. The fusion temperature of the materials employed as the sealant layer are generally hereinafter. The fusion temperature of PE, LDPE, HDPE and LLDPE are within a range of 120-150° C., that of PP and CPP are about 180° C., and the fusion temperature of PET employed as the package layer is over 230° C.
As materials employed as a barrier film having moisture permeability resistance, although aluminum is exemplified in the above example, it is not limited, and materials capable of forming thin films by means of sputtering can be employed. As for such materials, alumina (Al
2
O
3
), silicon oxide (SiO
2
), and silicon nitride (SiNx) can be employed.
In a conventional means for sealing the ends of the package members of the lithium ion secondary battery with a thin structure, generally, adhesive material with high adhesion for the metal material and the package members of the lead electrodes, is applied on a position where the ends of the package members are sealed, and pressure is applied on the position to be sealed. In another means, the adhesive material is only applied to surfaces of the sealed positions in each of the lead electrodes and the ends of the package members are applied pressure to each of the lead electrodes so as to seal the part.
However, in the conventional sealing structure and method of manufacturing the same using the adhesive material as described above, there are problems such that even if the package members can be completely sealed to principal surfaces of the lead electrodes, gaps are easy to be produced between sides of the lead electrodes and the package members, which causes an incomplete sealing state (or hermeticity decrease), thereby, insides of the batteries are susceptible to influence of temperature variations or influence from the outside, and by secular change in the batteries, the insides of the batteries deteriorates rapidly, which results in decrease of electromotive force and reduction of durability. Additionally, such batteries occurred the gaps causing degradation of battery capability, must be treated as a nonconforming battery, which results in productivity decrease.
SUMMARY OF THE INVENTION
The invention has been achieved in consideration of the above problems and its object is to provide a lithium ion battery with high productivity and excellent in hermeticity inside the battery covered with a package member by means of preventing sealing failures caused by a gap occurred between sides of a lead electrode and the package member, and a method of manufacturing the same.
A nonaqueous-electrolyte secondary battery according to the present invention comprises a laminating structure, in which at least a positive electrode and a negative electrode are laminated, a film-like or sheet-like package member for covering the laminating structure, a lead electrode whose one end joints to the laminating structure and the other end protrudes toward the outside from an end of the package member, and a sealing member, which is inserted between the end of the package member and the lead electrode by fusing a thermoplastic material, and seals the gap therebetween.
In a method of manufacturing a nonaqueous-electrolyte secondary battery according to the present invention, a step of sealing a gap between a lead electrode and an end of a package member, whereby a sealing member made of a thermoplastic material is inserted between the lead electrode and the end of the package member, wherein the electrode whose one end connects to the laminating structure and the other end protrudes from the end of the package member toward the outside, and the sealing member fuses in order to seal the gap therebetween.
Further, a method of manufacturing another nonaqueous-electrolyte secondary battery according to the present invention comprises a step of sealing a gap between a lead electrode and an end of a package member, whereby a sealing member made of a thermoplastic material is inserted between a lead electrode and the end of the package member, wherein the electrode whose one end joints to a laminating structure and the other end protrudes from an end of a package member toward the outside, a heater is applied to heat to the ends of the sealing member for fusion at temperature over its fusion temperature from the outer side.
Further more, a method of manufacturing another nonaqueous-electrolyte secondary battery according to the present invention comprises a step of sealing a gap between a lead electrode and an end of a package member, whereby the sealing member made o
Ono Takashi
Onozaki Tatsuo
Sugiyama Tsuyoshi
Chaney Carol
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
LandOfFree
Nonaqueous-electrolyte secondary battery and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nonaqueous-electrolyte secondary battery and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonaqueous-electrolyte secondary battery and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3332398