Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1998-07-30
2001-07-31
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S129000
Reexamination Certificate
active
06268087
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of preparing a lithium ion polymer battery which has high energy density and good cyclability. More particularly, the present invention relates to a method of preparing a lithium ion polymer battery composed of a carbon composite anode, a polymer electrolyte and a metallic oxide composite cathode, which prevents the exudation of liquid electrolyte by using a polymer matrix highly compatible with liquid electrolyte and improves interfacial adhesion between an electrolyte and electrodes.
BACKGROUND OF THE INVENTION
The lithium ion polymer batteries fabricated with a solid polymer electrolyte having a high ionic conductivity have advantages to solve the problems of the exudation of electrolyte solution and explosion, which have occurred in the lithium ion cell using liquid electrolyte. Also, if a solid polymer electrolyte is employed, it is possible to design various shapes of cell as well as to simplify the process of manufacturing the lithium ion polymer batteries. Since the lithium ion polymer battery has little self-discharge up to 5% and no memory effect, it is spotlighted as a next generation battery. A method of preparing a lithium ion polymer battery has been developed in many ways.
U.S. Pat. No. 5,491,041 discloses a solid state rechargeable electrochemical cell comprising a Li intercalating composite cathode, a solid polymer electrolyte separator, and a composite anode containing graphite, a polymer electrolyte and 12-crown-4-ether. The electrodes of the U.S. patent above are prepared by coating a current collector layer such as aluminium or copper foil with a cathode or an anode active material. However, the cell has a poor cyclability due to being separated the active material from the current collector layer during charge/discharge cycles. Further, the capacity of the cell per unit area cannot be increased due to the limitation to the thickness of electrodes.
U.S. Pat. No. 5,540,741 discloses a method of making a battery structure comprising forming a solid state positive electrode of a polymer, a plasticizer and an active material, forming a solid state negative electrode of the same polymer, a plasticizer and an active material, forming a separator membrane of the same polymer and a plasticizer, bonding said electrodes and said separator membrane to form a unitary cell structure, extracting a portion of said plasticizer from at least said separator membrane, and activating said battery by reswelling at least said separator membrane by contacting said unitary battery structure with an electrolytic salt solution. This method of the patent has an advantage that most of the steps for preparing the battery structure can be carried out under the atmosphere so as to avoid using an electrolyte solution which is sensitive to the moisture, and that the activating step is carried out under the anhydrous atmosphere. However, the battery prepared by the method has an exudation problem of liquid electrolyte, because the polymer electrolyte does not retain the liquid electrolyte for a long period. Also, it is not easy to retain a sufficient amount of the liquid electrolyte in the microporous polymer membrane.
Therefore, the present inventors have developed a lithium ion polymer battery to overcome the shortcomings of the conventional batteries and a method of preparing the same.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a method of preparing a lithium ion polymer battery which can prevent the exudation of liquid electrolyte.
Another object of the invention is to provide a method of preparing a lithium ion polymer battery which has a high capacity.
A further object of the invention is to provide a method of preparing a lithium ion polymer battery which has a good cyclability.
Other objects and advantages of this invention will be apparent from the ensuing disclosure and appended claims.
SUMMARY OF THE INVENTION
The present invention relates to a method of preparing a lithium ion polymer battery which has a high capacity and a good cyclability as well as no exudation of liquid electrolyte. The lithium ion polymer battery according to the present invention is prepared by the steps of forming electrode films, laminating the electrode films on both surfaces of a grid or extended metal so as to improve the interfacial adhesion between the electrode films, forming a polymer electrolyte film composed of a polymer, an electrolyte solution, and a filler, and laminating the composite anode, the polymer electrolyte and the composite cathode.
The lithium ion polymer battery according to the present invention comprises a carbon composite anode, a polymer electrolyte and a metallic oxide composite cathode.
The composite anode is prepared by forming an anode film by casting a composite anode slurry composed of an active material, a conducting material, a binder, a plasticizer and a solvent, laminating said anode film on both sides of a copper grid or a copper extended metal to prepare a composite anode, extracting plasticizer from the composite anode by immersing in a solvent, and activating the composite anode by immersing in an electrolyte solution to prepare an activated composite anode.
The polymer electrolyte film is made by casting a polymer electrolyte slurry composed of a polymer matrix, a liquid electrolyte solution of a lithium salt and an aprotic solvent, a filler and a solvent.
The composite cathode is prepared by forming a cathode film by casting a composite cathode slurry composed of an active material, a conducting material, a binder, a plasticizer and a solvent, laminating said cathode film on both sides of an aluminum grid or an aluminum extended metal to prepare a composite cathode, extracting plasticizer from the composite cathode by immersing in a solvent, and activating the composite cathode by immersing in an electrolyte solution to prepare an activated composite cathode.
The activated composite anode/polymer electrolyte film/activated composite cathode is laminated to obtain a lithium ion polymer battery structure. The lithium ion polymer battery is vacuum-packaged using a vacuum packaging apparatus.
The present invention has an advantage that most of the steps for preparing the battery structure can be carried out under the atmosphere so as to avoid using an electrolyte solution which is sensitive to the moisture, and that the activating step is carried out under the anhydrous atmosphere. Also, this invention is to provide a lithium ion polymer battery having a high capacity and a good cyclability, which can prevent the exudation of liquid electrolyte.
REFERENCES:
patent: 5491041 (1996-02-01), Abraham et al.
patent: 5540741 (1996-07-01), Gozdz et al.
patent: 5894656 (1999-04-01), Menon et al.
patent: 5928391 (1999-07-01), Lewin
patent: 6020087 (2000-02-01), Gao
Baek Chang-Woo
Kim Dong-won
Kim Young-Roak
Oh Boo-Keun
Sun Yang-Kook
Brouillette Gabrielle
Samsung Display Device Co., Ltd.
Wills M.
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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