Nonaqueous electrolyte battery having large capacity and...

Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode

Reexamination Certificate

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C429S233000, C429S241000, C429S242000, C429S245000

Reexamination Certificate

active

06541157

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonaqueous electrolyte battery and, more specifically, to a nonaqueous electrolyte battery having an improved negative electrode active material.
2. Description of the Background
Nonaqueous electrolyte secondary batteries using, as a negative electrode active material, metallic lithium, a lithium alloy, a lithium compound, a carbon material, or the like are anticipated to become good high energy density batteries and are now researched and developed extensively. So far, a wide variety of lithium ion batteries that use LiCoO
2
, LiMn
2
O
4
, or the like as a positive electrode material and a carbon material capable of inserting and de-inserting lithium as a negative electrode active material have been put into practical use.
On the other hand, although secondary batteries using, as a negative electrode active material, metallic lithium, a lithium alloy, a lithium compound are anticipated to exhibit a large capacity, they have not been put into practical use yet for the following main reasons. The use of metallic lithium is associated with problems that lithium deteriorates owing to reaction between a nonaqueous electrolyte liquid and metallic lithium and that desorption of the negative electrode active material that is caused by dendrite-like (bark-like) lithium produced by repetition of charging and discharging causes internal short circuiting or shortens the cycle life. To solve these problems, studies have been made in which a lithium alloy or a lithium compound is used as a negative electrode. However, in particular, in the case of using an alloy such as a lithium-aluminum alloy, although the charging/discharging efficiency is increased by virtue of reduction in the degree of reaction between the negative electrode active material and the nonaqueous electrolyte liquid, improvement in cycle life characteristic is insufficient because repetition of deep charging and discharging causes pulverization of the electrode.
From the viewpoint of increasing the negative electrode capacity, it has been proposed to use a chalcogen compound such as an oxide as a negative electrode active material. For example, it has been proposed to improve the cycle life characteristic by using SnO or SnO
2
(Japanese Unexamined Patent Publication Numbers Hei. 7-122274 and Hei. 7-235293) or an amorphous oxide such as SnSiO
3
or SnSi
1−x
P
x
O
3
. However, even the use of those chalcogen compounds has not yet improved or increased the cycle life and the capacity sufficiently. A need, therefore, continues to exist for a nonaqueous electrolyte battery which is not burdened by these problems.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a nonaqueous electrolyte battery having a large capacity and a long cycle life by using a negative electrode active material that has a large capacity and is superior in charging/discharging cycle performance.
The invention provides a nonaqueous electrolyte battery comprising a positive electrode, a negative electrode having a negative electrode active material that inserts and de-inserts an alkali metal, and a nonaqueous electrolyte. The negative electrode active material is a compound that is expressed by Formula (1):
A
z
MX
y
  (1)
where A is at least one element selected from the alkali metals, M is at least one element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt, and Mg, X is at least one element selected from the group consisting of B, N, Al, Si, P, Ga, Ge, As, In, Sn, Sb, Pb, and Bi, 0≦z≦20, and 0.2≦y≦6.


REFERENCES:
patent: 5618640 (1997-04-01), Idota et al.
patent: 9106808 (1997-04-01), None
Kepler et al. “Copper-tin anodes for rechargeable lithium batteries: an example of the matrix effect in an intermetallic system,” J. Power Sources 81-82 (1999) 383-387.*
J. Yang et al, “Small particle size multiphase Li-alloy anodes for lithium-ion-batteries”,Solid State Ionics, 90, 1996, pp. 281-287.

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