Chemistry: electrical current producing apparatus – product – and – Plural concentric or single coiled electrode
Reexamination Certificate
2001-11-01
2003-11-25
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Plural concentric or single coiled electrode
C429S211000, C429S225000, C429S233000, C429S241000, C429S242000
Reexamination Certificate
active
06653013
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a battery.
BACKGROUND OF THE INVENTION
A cylindrical lead acid battery is fabricated, for example, by spirally winding a strip-form positive electrode
21
and negative electrode
22
through a strip-form separator
23
to form a cylindrical electricity-generating element
24
as shown in
FIG. 6
, inserting this element
24
into a battery case (not shown), and sealing the case.
This electricity-generating element
24
formed by winding has current collecting lugs
21
a
and current collecting lugs
22
a
, which protrude on the upper side of the element
24
so as to be arranged on a straight line passing through the center of winding. The current collecting lugs
21
a
of the positive electrode
21
are arranged on one half of this straight line, i.e., on one side of the center of winding, while-the current collecting lugs
22
a
of the negative electrode
22
are arranged on the other half. Namely, the current collecting lugs
21
a
and
22
a
are arranged in such a manner that the current collecting lugs located on one side of the center of winding differ in polarity from those located on the other side. The current collecting lugs
21
a
of the positive electrode
21
are connected to a positive terminal through a positive-electrode strap (not shown) disposed to cover the current collecting lugs
21
a
. On the other hand, the current collecting lugs
22
a
of the negative electrode
22
are connected to a negative terminal through a negative-electrode strap (not shown).
The reasons why the current collecting lugs
21
a
and
22
a
are arranged on a straight line are explained below with respect to the current collecting lugs
21
a
of the positive electrode
21
. With respect to the current collecting lugs
22
a
of the negative electrode
22
, an explanation is omitted because the same explanation applies thereto.
In the case where the current collecting lugs
21
a
are arranged on a straight line as in
FIG. 6
, a linear strap can be used for connecting the current collecting lugs
21
a
thereto. However, if the current collecting lugs
21
a
are not arranged on a straight line, the strap should have a shape corresponding to the arrangement of the current collecting lugs and be larger than the linear one. Use of such a large positive-electrode strap is disadvantageous in that not only there is the possibility of contact with a negative-electrode strap but also the battery has an increased mass (weight) because the strap is made of, e.g., a lead alloy and is hence heavy. For these reasons, the current collecting lugs
21
a
are arranged on a straight line passing through the center of winding.
In order for the current collecting lugs
21
a
to be arranged on a straight line passing through the center of winding, the positive electrode
21
should have such a structure that the length over which the positive electrode
21
is spirally wound together with a separator
23
and a negative electrode
22
from one current collecting lug
21
a
to the next current collecting lug
21
a
to make one turn increases toward the outer side. This structure is further explained by reference to
FIG. 7
, which illustrates a grid
21
b
for the positive electrode
21
which has not been filled with an active material. This strip-form grid
21
b
, which has current collecting lugs
21
a
protruding on one of the longer sides, is located so that the distance D between two adjacent current collecting lugs
21
a
becomes longer toward the outer side. This distance D is determined, for example, in the following manner. The distance D between a current collecting lug
21
a
and the next current collecting lug
21
a
located on the outer side thereof is a value approximately satisfying the relationship
D=
2
&pgr;r
wherein r is the distance between the former current collecting lug
21
a
and the center of winding. As a result, all the current collecting lugs
21
a
are arranged on a straight line passing through the center of winding.
In conventional positive electrodes
21
, the current collecting lugs
21
a
have the same shape regardless of whether they are located in an inner region of the coil or in an outer region thereof. We found that the conventional positive electrodes have a problem that electricity-generating element
24
as a whole has an uneven distribution of the reaction of each active material. This problem is explained in more detail with respect to the case where charge/discharge current flows through a positive electrode
21
via current collecting lugs
21
a
. In an inner region of the coil, the area in which electricity should be collected by one current collecting lug
21
a
is smaller than in an outer region since the distance D between adjacent two of the current collecting lugs
21
a
in the inner region is small. Because of this, sufficient charge/discharge current can flow through the active material in the whole area via the current collecting lug
21
a.
In contrast, in an outer region of the coil, the area in which electricity should be collected by one current collecting lug
21
a
is large since the distance D between adjacent two of the current collecting lugs
21
a
in the outer region is large. Accordingly, sufficient charge/discharge current cannot flow through the active material in the whole area in this region via the current collecting lug
21
a
, which is the same shape as those in the inner region. In the outer region, the part of the active material which is located near the current collecting lugs
21
a
is preferentially used, and that part of the active material which is located apart from the current collecting lugs
21
a
remains unused. There is hence the possibility of a decrease in battery performance.
This problem applies not only to the positive electrode
21
but to the negative electrode
22
employing the grid
22
b
shown in
FIG. 8
, which has current collecting lugs
22
a
protruding therefrom.
Under the circumstances described above, an object of the invention is to provide a battery in which the electricity-generating element as a whole can have an even distribution of the reaction of each active material.
SUMMARY OF THE INVENTION
The invention provides a battery comprising an electricity-generating element comprising a strip-form positive electrode, a strip-form negative electrode, and a strip-form separator,
said positive electrode and said negative electrode being spirally wound through said separator and said positive electrode and said negative electrode respectively having current collecting lugs protruding from a side thereof,
wherein the pitches of the current collecting lugs become longer toward the outer periphery side, and the at least one current collecting lug that located on the outer side has a larger width than that located on the inner side.
In this battery, the electricity-generating element has a current collecting lug has a larger width than the adjacent current collecting lug located on the inner side thereof. Consequently, although the current collecting lugs in an outer region are located at a long pitch and the area to be covered by each current collecting lug in that region is wide, the charge/discharge current can sufficiently flow through the active material throughout the whole each area in that region. Therefore, the charge/discharge current can evenly flow through the electrode plates including their inner and outer parts, whereby the active materials can have an even reaction distribution.
The current collecting lugs of the positive electrode and those of the negative electrode are preferably arranged on the same line.
This linear arrangement is advantageous in that the strap to be connected to the current collecting lugs of the positive electrode or to the current collecting lugs of the negative electrode can have a linear shape and hence have a minimum size and mass (weight).
Furthermore, each current collecting lug preferably has a width L approximately satisfying the relationship L=r×&thgr;, wherein r is the distance betwe
Japan Storage Battery Co., Ltd.
Martin Angela J.
Ryan Patrick
LandOfFree
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