Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Include electrolyte chemically specified and method
Reexamination Certificate
2000-08-28
2003-02-18
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Include electrolyte chemically specified and method
C429S231950, C429S324000, C429S326000, C429S338000
Reexamination Certificate
active
06521375
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on application Ser. No. 1999-39887 filed in the Korean Industrial Property Office on Sep. 16, 1999, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery using the same and, more particularly, to an electrolyte for a rechargeable lithium battery exhibiting good cycle life characteristics.
(b) Description of the Related Art
In recent years, the development of miniaturized portable electronics has increased the needs for rechargeable batteries having a high capacity as well as a light weight. From the viewpoint of the capacity improvement per unit weight, the rechargeable lithium battery is superior to other types of rechargeable batteries because of the advantageous properties of lithium. That is, lithium has a high standard potential as well as a low electrochemical equivalent weight.
Metallic lithium has been used for the negative active material in a rechargeable lithium battery. However, during charging, lithium is electroplated onto the metallic lithium electrode, it deposits to form a dendric layer which induces a short circuit between the negative and positive active material. The problem of lithium reactivity toward the electrolyte is addressed by replacing lithium metal with carbon-based materials.
For the positive active material in the rechargeable lithium battery, transition metal oxides are used. Typical examples include LiCoO
2
, LiMn
2
O
4
, LiNiO
2
, LiNi
1-x
Co
x
O
2
(0<X<1) or LiMnO
2
. Manganese-based material such as LiMn
2
O
4
or LiMnO
2
is easiest to prepare, is less expensive than the other materials and has environmentally friendly characteristics, but it has low capacities. In particularly, LiMn
2
O
4
has a lower discharge capacity than LiCoO
2
and LiNiO
2
, experiences an abrupt drop in discharge capacity at high charge and discharge rates, and exhibits inferior cycle life characteristics due to the dissolution of manganese at high temperatures. LiCoO
2
is widely used as it has a good electrical conductivity and high battery voltage, but it is expensive. LiNiO
2
, on the other hand, is relatively inexpensive and has a high charge capacity, but it is difficult to produce and has safety problems.
The electrochemical performances of rechargeable lithium batteries depend on the reaction between the positive active material and an electrolyte or between the negative active material and an electrolyte, and thus the choice of an organic solvent in the electrolyte is critical to battery performance. There have been attempted to use various non-aqueous organic solvents for electrolytes. It is understood that an organic solvent is used alone, rechargeable lithium batteries exhibit no excellent electrochemical performances, and thus, two or three-component is used for electrolytes.
In the lithium ion battery, cycle life and capacity greatly depend on the surface reactivity between the electrolyte and the negative active material. Accordingly, the reactivity between the electrolyte and the negative active material, rather than the positive active material, should be considered when developing the electrolyte composition.
It has been proposed in U.S. Pat. No. 5,437,945 (Sony) to use a two-component for electrolytes. The electrolyte includes propylene carbonate and methyl ethyl carbonate. In addition, U.S. Pat. No. 5,474,862 (Matsushita) describes an electrolyte including aliphatic carbonate, cyclic carbonate and chain carbonate. Propylene carbonate exhibits good low-temperature characteristics, but the reduced cycle life characteristics.
Because rechargeable lithium batteries use non-aqueous solvents, no water exists in the electrolyte. However, a trace of water may exist as an impurity in the electrolyte. Water reacts with lithium salts in the electrolyte to generate acidic materials such as hydrogen halide (HX: X is halogen). Such acidic materials cause damage to a surface of the positive electrode and a surface of a passivation layer of the negative electrode, thereby deteriorating cycle life characteristics.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electrolyte for a rechargeable lithium battery exhibiting good cycle life characteristics.
It is another object of the present invention to provide the electrolyte for a rechargeable lithium battery exhibiting good safety characteristics.
These and other objects may be achieved by an electrolyte for a rechargeable lithium battery. The electrolyte includes silicon powder and a non-aqueous organic solvent. Silicon powder has good reactivity with hydrogen halide.
The present invention further provides a rechargeable lithium battery including an electrolyte including silicon powder and a non-aqueous organic solvent, a negative electrode formed with a resin binder and graphitic carbonaceous material from or into which lithium ions are deintercalated or intercalated as a negative active material, and a positive electrode formed with transition metal oxides from or into which lithium ions are deintercalated or intercalated as a positive active material.
REFERENCES:
patent: 5437945 (1995-08-01), Omaru et al.
patent: 5474862 (1995-12-01), Okuno et al.
patent: 5612155 (1997-03-01), Takami et al.
patent: 5648011 (1997-07-01), Blonsky
patent: 5658689 (1997-08-01), Kawakami et al.
patent: 5998065 (1999-12-01), Tsutsumi et al.
patent: 3-236170 (1991-10-01), None
patent: 9-283156 (1997-10-01), None
patent: 2001-110444 (2001-04-01), None
“Does Oil Remain on the Beaches 10 Years Later?”, Exxon Valdez Oil Spill Trustee Council 10-Year Report.
Hwang Duck-Chul
Jung Won-Il
Kweon Ho-Jin
Song Eui-Hwan
Christie Parker & Hale LLP
Mercado Julian
Ryan Patrick
Samsung SDI & Co., Ltd.
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