Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2001-01-31
2003-06-24
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S231000
Reexamination Certificate
active
06582850
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an organic-inorganic composite as a cathode material for a secondary lithium battery and a method for manufacturing the same, and, more particularly, to an organic-inorganic composite as a cathode material for a secondary lithium battery in which two different organic polymers are stabilized between V
2
O
5
layers by intercalation and a method for manufacturing the same.
PRIOR ART OF THE INVENTION
A secondary lithium battery is an energy storage device being capable of charging and discharging, which is widely used as a power source of small and/or portable electrical devices such as cellular phone, laptop computer and mobile telecommunication. Recently, development of the secondary battery that is lighter and has higher charge/discharge capacity is one of major issues. Secondary lithium battery comprises a cathode, an electrolyte and a negative electrode, in which charge/discharge characteristic of cathode material is one of most important factors to determine the capacity for energy storage in secondary lithium battery.
As for the cathode materials in secondary lithium battery, crystalline cobalt-, manganese- and nickel-based oxides are the most studied materials. Commercialized LiCoO
2
has high reduction-oxidation potential along with long term stability, but it has disadvantages of high cost and low charge/discharge capacity. In case of Li
2
Mn
2
O
4
, it has been considered as an alternative to conventional LiCoO
2
because of low cost, but it has still problem in terms of charge/discharge capacity and long term stability. For the case of LiNiO
2
, although it is better in theoretical discharge capacity than LiCoO
2
it has a difficulty in preparation. Therefore, there is a demand for a new electrode material to overcome the shortcomings of the crystalline transition metal oxides as described above.
Recent trends in the field of portable electrical devices for telecommunications are also on going to reduce power consumption, which requires a relatively low working voltage together with high energy density. To meet this end, the secondary battery with high charge/discharge capacity is required. Therefore, an attempt of synthesizing amorphous type, nano-particle and organic-inorganic compounds has been made to improve charge/discharge capacity.
Xerogel and/or aerogel type V
2
O
5
is proved to be a good material for cathode in secondary lithium battery, much better in lithium insertion/extraction performance than crystalline phase, by Smyrl group of Minnesota University. In particular, the two dimensional structure of V
2
O
5
allows organic molecules or ions to be intercalated into the V
2
O
5
layers. Recently, improved discharge capacity for electrochemical lithium insertion has been observed for the oxygen post-treated polyaniline (PANI)-intercalated V
2
O
5
nanocomposites, which is disclosed by Nazar group in Canada and Gomez-Romero group in Spain (“An organic-inorganic polyaniline/V
2
O
5
system”, The Journal of Electrochemical Society, vol. 146, no. 6, pp2029-2033, 1999.
In addition to the metal oxide-based electrode materials, organic materials can be utilized as a cathode in secondary lithium battery. An example is the 2,5-dimercapto-1,3,4-thiadiazole (DMcT)/PANI composite that demonstrates high discharge capacity of 185 mAh/g, which is reported by Oyama group in Japan (“dimercapto-polyaniline composite electrode for a lithium battery of high energy density”, Nature, vol. 373, no. 6515, p598-800, 1995).
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a composite material for a cathode in secondary lithium battery with excellent charge/discharge characteristics and a method for manufacturing the same.
In accordance with an aspect of the present invention, there is provided an organic-inorganic composite for use as a cathode in a secondary lithium battery comprising a V
2
O
5
xerogel in which poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT) and polyaniline are co-intercalated, where the nominal composition of V
2
O
5
, xerogel:PDMcT:PANI is preferably 1:0.2-1:0.2-2 in mole %.
In accordance with another aspect of the present invention, there is provided a method for manufacturing an organic-inorganic composite for use as a cathode in a secondary lithium battery, the method comprises the fllowing steps of: (a) preparing V
2
O
5
xerogel powder; (b) dissolving the V
2
O
5
xerogel powder in distilled water to form V
2
O
5
-water solution; (c) dissolving DMcT molecule in organic solvent to form DMcT solution; (d) adding slowly the V
2
O
5
-water solution to the DMcT solution; (e) adding aniline to the resultant of (d); (f) reacting the resultant of (e) for 24 hours at a room temperature and then filtering and washing; and (g) drying the resultant of (f), where drying temperature at the step (g) is ranging from the room temperature to 80° C.
And, in accordance with still another aspect of the present invention, there is provided the manufacturing method after the step (g), further comprising the step of undergoing thermal treatment in an oxygen gas atmosphere, where the temperature and the heating time is 80 to 120° C. and 3 to 10 hours, respectively.
REFERENCES:
patent: 5571292 (1996-11-01), Sotomura et al.
patent: 5665492 (1997-09-01), Sotomura
patent: 5723230 (1998-03-01), Naoi et al.
patent: 6340539 (2002-01-01), Yamaguchi et al.
M. Lira-Cantú and P. Gómez-Romero;The Organic-Inorganic Polyaniline/V2O5System; Journal of The Electrochemical Society, 146(6), pp. 2029-2033; (1999). (Month Unknown).
Eiichi Shouji and Daniel A. Buttry;New Organic-Inorganic Nanocomposite Materials for Energy Storage Applications; Langmuir 1999, 15, pp. 669-673; Nov. 17, 1998.
N. Oyama, et al,;Dimercaptan-polyaniline Composite Electrodes for Lithium Batteries with High Energy Density; Nature vol. 373, No. 6515, pp. 598-600; Feb. 16, 1995.
J.H. Harreld, et al.;Design and Synthesis of Inorganic-organic Hybrid Microstructures; International Journal of Inorganic Materials (1999) pp. 135-146. (Month Unknown).
C.G.Wu, et al.;Redox Intercalative Polymerization of Aniline in V2O5Xerogel. The Postintercalative intralamellar Polymer Growth in Polyaniline/Metal Oxide Nanocomposites Is Facilitated by Molecular Oxygen; Chem. Mater. 1996, pp. 1992-2004. (Month Unknown).
Bruno Alonso, et al.;Synthesis of Vanadium Oxide Gels from Peroxovanadic Acid Solutions: A51V NMR Study; Journal of Solid State Chemistry 148, pp. 16-19; Mar. 16, 1999.
Lei Yu, et al.;The Electrochemical Reversibility of the Polyaniline/Organodisulfide Composite Cathode Containing an Organomonothiol; Journal of the Electrochemical Society, 146(9), pp. 3230-3233 (1999); Apr. 26, 1999.
Chang Soon-Ho
Kim Kwang-Man
Park Nam-Gyu
Park Yong-Joon
Ryu Kwang-Sun
Electronics and Telecommunications Research Institute
Kalafut Stephen
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