Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
1998-08-28
2002-05-28
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S326000
Reexamination Certificate
active
06395430
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to Korean patent application No. 97-41936 filed Aug. 28, 1997, the content of which is incorporated herein by reference as if set forth in full.
FIELD OF THE INVENTION
The present invention relates to a hybrid polymer electrolyte for a lithium battery and a method of preparing the same and, more particularly, to a hybrid polymer electrolyte having a high ionic conductivity and a good stability.
BACKGROUND OF THE INVENTION
Generally, batteries are designed to convert the chemical energy contained in its active materials into electric energy by means of an electrochemical reaction. Among them, batteries using lithium metal or materials capable of intercalating and de-intercalating lithium ions as the negative electrode are called “lithium” batteries.
Lithium metal is attractive as the negative electrode material of the battery because it has a light weight and a high capacity per unit weight capable of outputting high voltage in the battery. Because of these outstanding features, the use of lithium has predominated in the development of high-performance primary and secondary batteries. However, the lithium battery has a potential safety problem particularly where the lithium metal is used for the negative electrode in conjunction with a liquid electrolyte.
Given this problem, an alternate way to make a battery is to use an electrolyte, such as a solid polymer electrolyte, which is less reactive with lithium. However, although a solid polymer electrolyte enhances the safety of the battery, it has lower ionic conductivity compared to a liquid electrolyte. For example, in a solid polymer electrolyte having high molecular polymers such as poly(ethylene oxide) and poly(propylene oxide), the ionic conductivity is in the range of about 10
−7
~10
−4
(&OHgr;.cm)
−1
at 20° C.~100° C. so that it is not practical for normal temperature applications. Thus, a polymer electrolyte having a practical conductivity as high as 10
−3
(&OHgr;.cm)
−1
at room temperature while ensuring the safety of the battery has been newly developed.
U.S. Pat. No. 5,252,413 discloses poly(vinyl chloride) electrolytes having improved ionic conductivity. However, when a Li/LiMn
2
O
4
battery is assembled with such an electrolyte, the charge/discharge voltage of the battery cannot be around 4V characteristic of the lithium battery but less than 3V due to the interfacial resistance at the lithium/electrolytes interface.
U.S. Pat. No. 5,296,318 discloses polymer electrolytes comprising a copolymer film of vinylidene fluoride and hexafluoropropylene entraining a solution of lithium salts therein.
U.S. Pat. No. 5,552,239 discloses plasticized hybrid polymer electrolytes comprising plasticizers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hybrid polymer electrolyte for a lithium battery and that has higher ionic conductivity and good stability.
In order to achieve this object and others, the present invention provides a hybrid polymer electrolyte including a copolymer matrix of poly(vinyl chloride) and poly(vinylidene chloride) having a plurality of pores, and a solution of an alkali metal salt in an organic solvent entrained in the pores of the copolymer matrix.
A method for preparing the hybrid polymer electrolyte includes the steps of obtaining a solution by dissolving an alkali metal salt and an organic solvent in tetrahydrofuran, obtaining a mixture by mixing a copolymer of poly(vinyl chloride) and poly(vinylidene chloride) with the solution, forming the mixture into a film, and evaporating off the tetrahydrofuran from the film.
A lithium battery with such a hybrid polymer electrolyte may be prepared by using lithium metal or materials capable of intercalating and de-intercalating lithium ions as the negative electrode.
REFERENCES:
patent: 5252413 (1993-10-01), Alamgir et al.
patent: 5296318 (1994-03-01), Gozdz et al.
patent: 5540741 (1996-07-01), Gozdz et al.
patent: 5552239 (1996-09-01), Gozdz et al.
patent: 5585039 (1996-12-01), Matsumoto et al.
patent: 5858264 (1999-01-01), Ichino et al.
Cho Jae-phil
Kim Geun-bae
Park Yong-chul
Brouillette Gabrielle
Christie Parker & Hale LLP
Samsung Display Devices Co. Ltd.
Wills M.
LandOfFree
Hybrid polymer electrolyte for lithium 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 Hybrid polymer electrolyte for lithium battery and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hybrid polymer electrolyte for lithium battery and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2913188