DESCRIPTION
EXPANDED LATTICE BODY AND PRODUCTION METHOD THEREFOR, AND
POLAR PLATE AND LEAD STORAGE BATTERY USING SAID EXPANDED LATTICE
5 BODY
TECHNICAL FIELD
[1:1001] The present disclosure relates to an expanded grid body including a mesh part
formed by reciprocal expansion, to a method for manufacturing the expanded grid body, and
10 to an electrode plate and a lead-acid battery using the expanded grid body.
BACKGROUND ART
[0002] Patent Document 1 describes the following battery electrode grid (i.e., the expanded
grid body).
15 [0003] The battery electrode grid includes a frame part and an expanded part integrally
formed with the frame part. The expanded part includes a plurality of wires, a plurality of
intersections at each of which the wires intersect with each other, and a plurality of meshes
each surrounded by the wires and the intersections.
[0004] Each intersection positioned at one of ends of a metal sheet in an expansion
20 direction thereof and each intersection positioned at the other end of the metal sheet are set to
the same thickness. In other words, each intersection positioned at a column closest to the
fi-ame part and each intersection positioned at a column farthest from the frame part are set to
the same thickness. Thus, detachment of an active material is less likely to occur.
[0005] Patent Document 2 describes the following expanded grid body for lead-acid
25 battery. The expanded grid body for lead-acid battery is formed in such a manner that a lead
alloy sheet is expanded. The minimum inner radius of curvature of each part surrounded by
grid bars formed by expansion is equal to or greater than 0.1 rnm. This reduces deformation
of the expanded grid body for lead-acid battery, resulting in improvement of life performance.
[0006] Patent Document 3 describes the following expansion. The expansion is applied
5 to a strip interposed between a die and a cutter. The length of a non-processed part between
adjacent ones of processed parts formed in the strip is equal to or shorter than the length of a
flat tip end part of a trapezoidal blade edge of the cutter. This reduces or prevents rapture of
each processed part in the vicinity of a corresponding one of intersections of an expanded grid
body.
10 [0007] Patent Document 4 describes the following expanded grid body for lead-acid
battery.
[0008] An expanded mesh part is formed so as to continue to a frame formed with a current
collector ear part. Diamond-shaped meshes are positioned adjacent to each other in an
expansion direction such that each intersection is interposed between adjacent ones of the
15 meshes. Each intersection is formed with a part in which a distance between a first virtual
line and a second virtual line is d (d > 0). This reduces stress concentration on the
intersections, and cracking and corrosion due to such stress concentration.
[0009] The first virtual line is a virtual line passing through a peak at the intersection of
one of adjacent ones of the diamond-shaped meshes and being parallel to the expansion
20 direction. The second virtual line is a virtual line passing through a peak at the intersection
of the other one of adjacent ones of the diamond-shaped meshes and being parallel to the
expansion direction. The one of adjacent ones of the diamond-shaped meshes is closer to the
frame than the other one of adjacent ones of the diamond-shaped meshes is to the frame.
25 CITATION LIST
PATENT DOCUMENT
[OO 101 PATENT DOCUMENT 1 : Japanese Unexamined Patent Publication No. H 1 1 -
016576
PATENT DOCUMENT 2: Japanese Unexamined Patent Publication No. 2002-
5 075380
PATENT DOCUMENT 3: Japanese Unexamined Patent Publication No. 2003-
191027
PATENT DOCUMENT 4: Japanese Unexamined Patent Publication No. 2007-
066786
10
SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0011] However, in the techniques described in Patent Documents 1-4, there is a
disadvantage that adhesion between the mesh part of the expanded grid body and an active
15 material with which the mesh part is filled is low.
[0012] In the view of the foregoing, the present disclosure aims to enhance, in an expanded
grid body and a lead-acid battery using the expanded grid body, adhesion between a mesh part
of the expanded grid body and an active material.
20 SOLUTION TO THE PROBLEM
[0013] In order to accomplish the foregoing aim, a first expanded grid body of the present
disclosure includes a mesh part formed by reciprocal expansion. The mesh part is formed in
such a manner that, while a sheet is being intermittently fed between a cutting die including a
cutting blade and an expanding die including an expanding blade, the expanding die
25 reciprocates up and down to form a slit in the sheet and to downwardly expand part of the
sheet contacting the expanding blade. The mesh-part includes a grid bar and an intersection.
The intersection includes a first part and a second part. The first and second parts are
arranged so as to be displaced from each other in an up-down direction.
[0014] Ln order to accomplish the foregoing aim, a second expanded grid body of the
5 present disclosure includes a mesh part formed by reciprocal expansion. The mesh part is
formed in such a manner that, while a sheet is being intermittently fed between a cutting die
including a cutting blade and an expanding die including an expanding blade, the expanding
die reciprocates up and down to form a slit in the sheet and to downwardly expand part of the
sheet contacting the expanding blade, and then is pressed and shaped in such a manner that
10 the mesh part is fed between rollers. The mesh part includes a grid bar and an intersection.
The intersection includes a first part, a second part, a first stepped part, and a second stepped
part. The first and second parts are arranged so as to be displaced from each other in an updown
direction and to overlap with each other as viewed in a pressing direction. The first
and second stepped parts are formed in such a manner that the first and second parts overlap
15 with each other as viewed in the pressing direction. The grid bar interposed between the
first and second parts is curved relative to the first and second parts.
ADVANTAGES OF THE INVENTION
[0015] According to the expanded grid body of the present disclosure, the surface area of
20 the intersection can be expanded. Thus, adhesion between the mesh part of the expanded
grid body and an active material with which the mesh part is filled can be enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] [FIG. 11 FIG. l(a) is a plan view illustrating the structure of an expanded grid
25 body of an embodiment of the present disclosure. FIG. l(b) is a cross-sectional view
illustrating part of the expanded grid body of the embodiment of the present disclosure, and
specifically a cross-sectional view along an Ib-Ib line illustrated in FIG. l(a).
[FIG. 21 FIGS. 2(a) and 2(b) are views illustrating the partial structure of the
expanded grid body of the embodiment of the present disclosure. Specifically, FIG. 2(a) is a
5 perspective view illustrating the structure of a part enclosed by a dashed line in FIG. l(a), and
FIG. 2(b) is a cross-sectional view along an IIb-IIb line illustrated in FIG. 2(a).
[FIG. 31 FIGS. 3(a)-3(c) are plan views the partial structure of first to third
expansion dice used for forming a mesh part of the expanded grid body of the embodiment of
the present disclosure.
[FIG. 41 FIGS. 4(a)-4(c) are views for explaining a relationship among first and
second parts and expanding blades.
[FIG. 51 FIG. 5(a) is a plan view illustrating the structure of an expanded grid
body of a variation of the embodiment of the present disclosure. FIG. 5(b) is a crosssectional
view illustrating the partial structure of the expanded grid body of the variation of
15 the embodiment of the present disclosure, and specifically a cross-sectional view along a Vb-
Vb line illustrated in FIG. 5(a).
[FIG. 61 FIGS. 6(a) and 6(b) are views illustrating the partial structure of the
expanded grid body of the variation of the embodiment of the present disclosure.
Specifically, FIG. 6(a) is a perspective view illustrating the structure of a part enclosed by a
20 dashed line in FIG. 5(a), and FIG. 6(b) is a cross-sectional view along a VIb-VIb line
illustrated in FIG. 6(a).
[FIG. 71 FIG. 7(a) is a view for explaining the width of the first part, the width of
the second part, the height of a first stepped part, the height of a second stepped part, and the
width of the first stepped part. FIG. 7(b) is a view for explaining the width of the first
25 stepped part.
[FIG. 81 FIG. 8 is a view for explaining a gap.
[FIG. 91 FIG. 9(a) is a view of a pre-shaped mesh part. FIG. 9(b) is a view of a
shaped mesh part.
[:FIG. 101 FIGS. 10(a) and 10(b) are views illustrating the partial structure of the
5 expansion die. Specifically, FIG. 10(a) is a plan view, and FIG. 10(b) is a perspective view.
[FIG. 111 FIG. 11 is a plan view for explaining a relationship among slits and
expanding blades, and illustrates the partial structure of a sheet.
[:FIG. 121 FIG. 12(a) is a plan view illustrating the structure of a conventional
expanded grid body. FIG. 12(b) is a cross-sectional view illustrating the partial structure of
10 the conventional expanded grid body, and specifically a cross-sectional view along an XIIb-
XIIb line illustrated in FIG. 12(a).
[FIG. 131 FIGS. 13(a) and 13(b) are views illustrating the partial structure of the
conventional expanded grid body. Specifically, FIG. 13(a) is a perspective view illustrating
the structure of a part enclosed by a dashed line illustrated in FIG. 12(a), and FIG. 13(b) is a
15 cross-sectional view along an XIIIb-XIIb line illustrated in FIG. 13(a).
[FIG. 141 FIG. 14 is a view for explaining a gap.
[FIG. 151 FIG. 15 is a view for explaining a relationship among first and second
parts and expanding blades.
[FIG. 161 FIG. 16(a) is a view of a pre-shaped mesh part. FIG. 16(b) is a view
20 of a shaped mesh part.
[FIG. 171 FIG. 17 is a graph showing a relationship between the height ratio of the
stepped part and the percentage of detached active material.
[FIG. 181 FIG. 18 is a graph showing a relationship between the width ratio of the
stepped part and the percentage of detached active material.
2 5 [FIG. 191 FIG. 19 is a graph showing a relationship between a ratio t21tl and the
percentage of detached active material.
[FIG. 201 FIG. 20(a) is a view for explaining the length of a body and the length
of an end part. FIG. 20(b) is a view for explaining the length of the body, the length of the
end part, and the angle of the end part.
DESCRIPTION OF EMBODIMENTS
[OO 171 (Embodiment)
Reciprocal Expansion
In order to facilitate understanding of an expanded grid body of an embodiment of
10 the present disclosure, reciprocal expansion will be described before description of the
expanded grid body of the present embodiment. A mesh part of the expanded grid body of
the present embodiment is formed by the reciprocal expansion.
[OO 181 The reciprocal expansion is a process using an expansion die.
[0019] The structure of the expansion die will be described with reference to FIGS. lO(a)
15 andlO(b).
[0020] Referring to FIGS. lO(a) and lO(b), the expansion die includes a cutting die 2 1 and
an expanding die 23. The cutting die 21 includes a plurality of cutting blades 22. The
expanding die 23 includes a plurality of expanding blades 24.
[0021] While a sheet is being intermittently fed between the cutting die 21 and the
20 expanding die 23 in a sheet feeding direction (see FIGS. lO(a) and 10(b)), the expanding die
23 is reciprocating up and down (in a direction perpendicular to a surface of the sheet, i.e., in
a sheet thickness direction). Note that intermittent feeding of the sheet means that the sheet
are fed at certain intervals. In other words, feeding of the sheet and cessation of feeding of
the sheet are alternately repeated.
25 [0022] Downward movement of the expanding die 23 causes the expanding blades 24 to
contact the sheet, and causes each side surface of the expanding blades 24 to contact a
corresponding one of side surfaces of the cutting blades 22. Accordingly, while the sheet
between the expanding blade 24 and the cutting blade 22 is being cut such that slits are
formed, each part of the sheet contacting a corresponding one of the expanding blades 24 is
5 being expanded downward. At this point, feeding of the sheet is stopped. While the
expanding die 23 is moving upward such that the expanding blades 24 are apart from the
sheet, feeding of the sheet is resumed.
[0023] The sheet is intermittently fed between the cutting die 21 and the expanding die 23.
Meanwhile, reciprocal movement of the expanding die 23 successively forms the slits from an
10 end part toward a center part in the sheet, as well as successively and downwardly expanding
each part of the sheet contacting a corresponding one of the expanding blades 24. In this
manner, the mesh part is formed in the sheet. The end part of the sheet means an end part of
the sheet in a direction perpendicular to the sheet feeding direction.
[0024] As described above, the mesh part is formed by the reciprocal expansion.
15 [0025] After formation of the mesh part, the mesh part may be pressed and shaped in such
a manner that the mesh part is fed between rollers. Specifically, after the mesh part is
formed in the sheet, the sheet may be fed between the rollers. Accordingly, the mesh part
(i.e., the end part of the sheet) extending obliquely downward from the center part (i.e., part of
the sheet where no mesh part is formed) of the sheet may be shaped so as to be flat relative to
20 the center part of the sheet.
[0026] FIG. 11 illustrates a relationship among slits and expanding blades, and is a plan
view illustrating the partial structure of a sheet. Each line 26 illustrated in FIG. 11 indicates
a slit line formed in a sheet 25. The sheet 25 is cut along the lines 26 such that slits are
formed. Each shaded part 27 illustrated in FIG. 11 indicates part of the sheet 25 which
25 comes into contact with a corresponding one of expanding blades. The shaded parts 27 are
expanded downward in such a manner the expanding blades move downward.
[0027] The expanded grid body of the present embodiment will be described in comparison
with a conventional expanded grid body.
[0028] A mesh part of the conventional expanded grid body is formed by reciprocal
5 expansion as in the mesh part of the expanded grid body of the present embodiment.
[0029] The mesh part of the expanded grid body of the present embodiment is formed
using the expansion die of the present embodiment. On the other hand, the mesh part of the
conventional expanded grid body is formed using a conventional expansion die.
[0030] The expansion die of the present embodiment and the conventional expansion die
10 are different from each other in a set value for bottom dead point of an expanding blade.
Alternatively, the expansion die of the present embodiment and the conventional expansion
die are different from each other in the shape of the expanding blade. Thus, the expanded
grid body of the present embodiment and the conventional expanded grid body are different
from each other in the structure thereof.
15 [0031] First, the structure of the conventional expanded grid body will be described with
reference to FIGS. 12(a), 12(b), 13(a), 13(b), 14, and 15.
[0032] The conventional expanded grid body is an expanded grid body including a preshaped
mesh part.
COO331 Referring to FIG. 12(a), a conventional expanded grid body 3 1 includes a mesh part
20 32, a grid frame 33, and a current collector ear part 34. The mesh part 32 includes grid bars
35 and intersections 36.
[0034] Referring to FIGS. 12(b), 13(a), and 13(b), each intersection 36 includes a first part
36a and a second part 36b.
[0035] A width W36x of the intersection 36 as illustrated in FIG. 13(a) corresponds to a
25 distance (see "Wx" in FIG. 11) between adjacent ones of the slits in the sheet feeding
direction. A width W36y of the intersection 36 as illustrated in FIG. 13(b) corresponds to a
distance (see "Wy" in FIG. 11) between adjacent ones of the slits in the direction
perpendicular to the sheet feeding direction. A width W36z of the intersection 36 as
illustrated in FIG. 13(b) corresponds to the thickness of a sheet used in formation of the mesh
5 part 32 of the conventional expanded grid body 3 1.
[0036] Referring to FIG. 14, gaps 37 are formed in the mesh part 32.
[0037] A part 38a illustrated in FIG. 15 (identical to FIG. 13(a)) is part of the mesh part 32
which comes into contact with a tip end of the expanding blade. A part 38b illustrated in
FIG. 15 is part of the mesh part 32 which comes into contact with an end of the expanding
10 blade. In the present specification, the "end of the expanding blade" means one of both side
ends of the expanding blade. As will be seen from FIGS. 13(a) and 15, the first part 36a
includes the part 38a. On the other hand, the second part 36b includes the part 38b. Thus,
in the present specification, the "first part 36a" means part of the mesh part 32 including the
part 38a which comes into contact with the tip end of the expanding blade. On the other
15 hand, the "second part 36b" means part of the mesh part 32 including the part 38b which
comes into contact with the end of the expanding blade.
[0038] As described above, the conventional expanded grid body is the expanded grid body
including the pre-shaped mesh part. The mesh part of the conventional expanded grid body
is not shaped after the mesh part is formed by the reciprocal expansion.
20 [0039] However, the mesh part may be shaped after the mesh part is formed by the
reciprocal expansion. Thus, comparison between the structure of the pre-shaped mesh part
and the structure of the shaped mesh part will be described below. FIG. 16(a) is a view of
the pre-shaped mesh part, and FIG. 16(b) is a view of the shaped mesh part.
[0040] Referring to FIG. 16(b), the mesh part is shaped in such a manner that the mesh part
25 is pressed in a pressing direction.
[0041] As will be seen from FIGS. 16(a) and 16(b), if the conventional expansion die is
used, no change is made between the structure before shaping and the structure after shaping.
On the other hand, if the expansion die of the present embodiment is used, a change is, as will
be seen from FIGS. 9(a) and 9(b), made between the structure before shaping and the
5 structure after shaping.
[0042] FIG. 16(b) is illustrated as if no deformation occurs at each comer part enclosed by
a solid line in FIG. 16(b). However, deformation may occur at the comer part(s).
[(I0431 Next, the expanded grid body of the present embodiment will be described with
reference to FIGS. l(a), l(b), 2(a), 2(b), 3(a)-3(c), and 4(a)-4(c).
10 [0044] The expanded grid body of the present embodiment is an expanded grid body
including a pre-shaped mesh part.
[a0451 Referring to FIG. l(a), an expanded grid body 1 of the present embodiment includes
a mesh part 2, a grid frame 3, and a current collector ear part 4. The mesh part 2 includes
grid bars 5 and intersections 6.
15 [0046] Referring to FIGS. l(b), 2(a), and 2(b), the intersection 6 includes a first part 6a and
a second part 6b.
[0047] The first part 6a and the second part 6b are arranged so as to be displaced from each
other in an up-down direction. In the present specification, the "up-down direction" means a
direction in which the expanding die (see "23" in FIG. 10) reciprocates.
20 [0048] A width W6x of the intersection 6 as illustrated in FIG. 2(a) corresponds to the
distance (see "Wx" in FIG. 11) between adjacent ones of the slits in the sheet feeding
direction. A width W6y of the intersection 6 as illustrated in FIG. 2(b) corresponds to the
distance (see "WyYy in FIG. 11) between adjacent ones of the slits in the direction
perpendicular to the sheet feeding direction. A width W6a of the first part 6a and a width
25 W6b of the second part 6b as illustrated in FIG. 2(b) each correspond to the thickness of a
sheet used in formation of the mesh part 2 of the expanded grid body 1 of the present
embodiment.
[0049] The mesh part 2 of the expanded grid body 1 of the present embodiment is formed
using a first expansion die illustrated in FIG. 3(a), a second expansion die illustrated in FIG.
5 3(b), or a third expansion die illustrated in FIG. 3(c). FIGS. 3(a)-3(c) are views illustrating
the state in which an expanding die moved downward with a sheet being fed between a
cutting die and the expanding die.
[(3050] First Expansion Die
The first expansion die includes the cutting die and the expanding die. Referring
10 to FIG. 3(a), the cutting die includes a cutting blade 8. The expanding die includes an
expanding blade 9A. The expanding blade 9A includes a body 9a. In the present
specification, the "body 9a" is part of the expanding blade 9A which comes into contact with
the first part 6a and the grid bar 5.
[0051] The conventional expansion die and the first expansion die are different from each
15 other in the following point.
[0052] A set value for bottom dead point of the expanding blade 9A of the present
embodiment is greater than a set value for bottom dead point of a conventional expanding
blade. The bottom dead point means a lowermost point of a vertically-reciprocating
expanding blade. The set value for bottom dead point corresponds to a distance between a
20 sheet surface and the lowermost point of the expanding blade.
[0053] The conventional expanding blade has a shape similar to that of the expanding
blade 9A of the present embodiment. However, the set value for bottom dead point of the
expanding blade 9A of the present embodiment is, as described above, greater than the set
value for bottom dead point of the conventional expanding blade.
25 [0054] Second Expansion Die
The second expansion die includes the cutting die and the expansion die.
Referring to FIG. 3(b), the cutting die includes a cutting blade 8. The expansion die includes
an expanding blade 9B.
[0055] The first expansion die and the second expansion die are different from each other
5 in the following point. Shaded parts illustrated in FIG. 3(b) are parts different from FIG.
3(a).
[0056] Referring to FIG. 3(b), the expanding blade 9B of the present embodiment includes
a body 9a and end parts 9b each connected to a corresponding one of ends of the body 9a. In
the present specification, the "end parts 9b" are parts which come into contact with part of the
10 second part 6b.
[0057] Third Expansion Die
The thrd expansion die includes the cutting die and the expansion die. Referring
to FIG. 3(c), the cutting die includes a cutting blade 8. The expansion die includes an
expanding blade 9C.
15 [0058] The first expansion die and the third expansion die are different from each other in
the following point. Shaded parts illustrated in FIG. 3(c) are parts different from FIG. 3(a).
[0059] Referring to FIG. 3(c), the expanding blade 9C of the present embodiment includes
a body 9a and end parts 9c each connected to a corresponding one of ends of the body 9a.
An inclination angle (see " A in FIG. 20(b) described later) of a lower surface of the end part
20 9c relative to a lower surface of the body 9a is preferably equal to or less than 10". In the
present specification, the "end parts 9c" are parts which come into contact with part of the
second part 6b.
[0060] Reasons for realizing the structure illustrated in FIGS. 2(a) and 2(b) by using the
first, second, or third expansion die are as follows.
25 [0061] In the case of the first expansion die, the set value for bottom dead point of the
expanding blade 9A of the present embodiment is greater than the set value for bottom dead
point of the conventional expanding blade, and therefore the second part 6b is indirectly
pressed in a downward direction. In the present specification, the "up-down direction"
means, as described above, the direction in which the expanding die reciprocates. Thus, the
"downward direction" means the down direction of the up-down direction.
[0062] In the case of the second expansion die, the end parts 9b contact part of the second
part 6b to press the second part 6b in the downward direction.
[0063] In the case of the third expansion die, the end parts 9c contact part of the second
part 6b to press the second part 6b in the downward direction.
10 [0064] Thus, the second part 6b positioned on a near side in the plane of paper of FIGS.
3(a)-3(c) is displaced in the downward direction relative to part of a sheet positioned on a far
side in the plane of paper of FIGS. 3(a)-3(c). Subsequently, part of the sheet adjacent to the
second part 6b in a near-far direction forms a first part. Consequently, the first part 6a and
the second part 6b are displaced from each other in the up-down direction as illustrated in
15 FIGS. 2(a) and 2(b).
[0065] In the case where the first expansion die is used, a part 10a illustrated in FIG. 4(a)
(identical to FIG. 2(a)) is part of the mesh part 32 which comes into contact with a tip end of
the expanding blade 9A. A part lob illustrated in FIG. 4(a) is part of the mesh part 32 which
comes into contact with an end (i.e., an end of the body 9a) of the expanding blade 9A. As
20 will be seen from FIGS. 2(a) and 4(a), the first part 6a includes the part 10a. On the other
hand, the second part 6b includes the part lob. Thus, in the present specification, the "first
part 6a" is part of the mesh part 32 including the part 10a which comes into contact with the
tip end of the expanding blade 9A, whereas the "second part 6b" is part of the mesh part 32
including the part lob which comes into contact with the end (i.e., the end of the body 9a) of
25 the expanding blade 9A.
[0066] In the case where the second expansion die is used, a part 1 la illustrated in FIG.
4(b) (identical to FIG. 2(a)) is part of the mesh part 32 which comes into contact with a tip
end of the expanding blade 9B. A part 1 lb illustrated in FIG. 4(b) is part of the mesh part 32
which comes into contact with an end of the expanding blade 9B. A part 1 lc illustrated in
5 FIG. 4(b) is part of the mesh part 32 which comes into contact with an end of the body 9a.
As will be seen from FIGS. 2(a) and 4(b), the first part 6a includes the part 1 la. On the
other hand, the second part 6b includes the part 1 lb and the part 1 lc. Thus, in the present
specification, the "first part 6a" is part of the mesh part 32 including the part 1 la which comes
into contact with the tip end of the expanding blade 9B, whereas the "second part 6b" is part
10 of the mesh part 32 including the part 1 lb which comes into contact with the end of the
expanding blade 9B and the part 1 lc which comes into contact with the end of the body 9a.
[(I0671 In the case where the third expansion die is used, a part 12a illustrated in FIG. 4(c)
(identical to FIG. 2(a)) is part of the mesh part 32 which comes into contact with a tip end of
the expanding blade 9C. A part 12b illustrated in FIG. 4(c) is part of the mesh part 32 which
15 comes into contact with an end of the expanding blade 9C. A part 12c illustrated in FIG.
4(c) is part of the mesh part 32 which comes into contact with an end of the body 9a. As
will be seen from FIGS. 2(a) and 4(c), the first part 6a includes the part 12a. On the other
hand, the second part 6b includes the part 12b and the part 12c. Thus, in the present
specification, the "first part 6a" is part of the mesh part 32 including the part 12a which comes
20 into contact with the tip end of the expanding blade 9C, whereas the "second part 6b" is part
of the mesh part 32 including the part 12b which comes into contact with the end of the
expanding blade 9C and the part 12c which comes into contact with the end of the body 9a.
[0068] According to the present embodiment, the surface area of each intersection 6 can be
expanded. Thus, adhesion between the mesh part 2 and an active material with which the
25 mesh part 2 is filled can be enhanced.
[0069] In the case where the expanded grid body of the present embodiment is used as an
expanded grid body for positive electrode, the adhesion between the mesh part 2 and the
active material can be enhanced, and therefore the amount of detached active material can be
decreased. Accordingly, life duration can be extended.
5 [0070] Further, in the case where the expanded grid body of the present embodiment is
used as the positive electrode expanded grid body, the first part 6a and the second part 6b are
arranged so as to be displaced from each other in the up-down direction (i.e., the direction in
which the expanding die reciprocates), and therefore great deformation of the positive
electrode expanded grid body in the up direction (i.e., an upward direction in the plane of
10 paper of FIG. l(a)) can be reduced. Thus, occurrence of short circuit can be reduced.
Consequently, the life duration can be extended.
[(I0711 On the other hand, in the case where the expanded grid body of the present
embodiment is used as an expanded grid body for negative electrode, the adhesion between
the mesh part 2 and the active material can be enhanced, and therefore occurrence of cracks
15 between the active material and the negative electrode expanded grid body due to
expansion/contraction of the active material can be reduced. Thus, the life duration can be
extended.
[0072] (Variation of the Embodiment)
An expanded grid body of a variation of the embodiment of the present disclosure
20 will be described below with reference to FIGS. 5(a), 5(b), 6(a), 6(b), 7(a), 7(b), 8, 9(a), and
9(b).
[0073] The present variation and the foregoing embodiment are different from each other
in the following point. In the foregoing embodiment, after the mesh part is formed by the
reciprocal expansion, the mesh part is not shaped. On the other hand, in the present
25 variation, after a mesh part is formed by reciprocal expansion, the mesh part is shaped.
Thus, the expanded grid body of the present variation is an expanded grid body including a
shaped mesh part.
[0074] Referring to FIG. 5(a), an expanded grid body 1 of the present variation includes a
mesh part 2, a grid frame 3, and a current collector ear part 4. The mesh part 2 includes grid
5 bars 5 and intersections 16.
[0075] Referring to FIGS. 5(b), 6(a), and 6(b), each intersection 16 includes a first part 6a,
a second part 6b, a first stepped part 6c, and a second stepped part 6d.
[0076] The first part 6a and the second part 6b are arranged so as to be displaced in an updown
direction, and are arranged so as to overlap with each other as viewed in a pressing
10 direction. In the present specification, the "up-down direction" means a direction in which
an expanding die (see "23" in FIG. 10) reciprocates. The "pressing direction" means a
direction (see FIG. 9(b) which will be described later) in which the mesh part is pressed upon
shaping thereof.
[0077] The first stepped part 6c and the second stepped part 6d are formed in such a
15 manner the first part 6a and the second part 6b overlap with each other as viewed in the
pressing direction.
[0078] Each grid bar 5 interposed between the first part 6a and the second part 6b is curved
relative to the first parts 6a and the second parts 6b.
[0079] A width W6cx of the first stepped part 6c illustrated in FIG. 7(b) corresponds to a
20 distance (see "Wx" in FIG. 11) between adjacent ones of slits in a sheet feeding direction. A
width W6a of the first part 6a illustrated in FIG. 7(a) and a width W6b of the second part 6b
illustrated in FIG. 7(a) each correspond to the thickness of a sheet in formation of the mesh
part 2 of the expanded grid body 1 of the present variation.
[0080] Referring to FIG. 8, gaps 7 are formed in the mesh part 2. The volume of the gap
25 7 of the present variation is less than that of a conventional gap ("37" in FIG. 14).
[0081] Reasons for realizing the structure illustrated in FIGS. 6(a) and 6(b) by shaping are
as follows.
[0082] Referring to FIG. 9(a), shaping is performed in the state in which the first part 6a
and the second part 6b are displaced from each other in the up-down direction (i.e., the
5 direction in which the expanding die reciprocates). Thus, the first part 6a and the second
part 6b overlap, referring to FIG. 9(b), with each other as viewed in the pressing direction.
Since the first part 6a and the second part 6b overlap with each other as viewed in the pressing
direction, part of the first part 6a and part of the second part 6b are pressed toward the outside.
Consequently, the first stepped part 6c and the second stepped part 6d are formed.
10 [0083] As in FIG. 16(b), FIG. 9(b) is illustrated as if no deformation occurs at each corner
part. However, deformation may occur at the corner part(s).
[0084] According to the present variation, advantages similar to those of the foregoing
embodiment can be realized.
[0085] A calcium (Ca) concentration and a tin (Sn) concentration in a lead alloy sheet used
15 in formation of the mesh part 2 of the expanded grid body 1 of the foregoing embodiment and
the variation thereof will be described below.
[0086]
Ca Concentration
The Ca concentration in a lead alloy sheet for positive electrode is preferably equal
20 to or higher than 0.04 wt% and equal to lower than 0.07 wt%.
[0087] If the Ca concentration is lower than 0.04 wt%, there is a possibility that the
strength of the positive electrode expanded grid body is lowered. On the other hand, if the
Ca concentration is equal to or higher than 0.08 wt%, extension of a crystal grain boundary of
the positive electrode lead alloy sheet results in lowering of corrosion resistance of the
25 positive electrode expanded grid body, and therefore there is a possibility that the positive
electrode expanded grid body is oxidized and corroded.
[0088] Sn Concentration
The Sn concentration in the positive electrode lead alloy sheet is preferably equal to
or higher than 1.0 wt% and equal to or lower than 2.0 wt%.
5 [0089] If the Sn concentration is lower than 1.0 wt%, there is a possibility that the strength
of the positive electrode expanded grid body is lowered. On the other hand, if the Sn
concentration is higher than 2.0 wt%, there is a possibility that the mesh part of the positive
electrode expanded grid body is curved at the end of life. Since a sufficient electrolyte is not
supplied due to compression of an electrode plate group, there is a possibility that a capacity
10 decreases.
[0090]
Ca Concentration
The Ca concentration in a lead alloy sheet for negative electrode is preferably equal
to or higher than 0.06 wt% and equal to or lower than 0.08 wt%.
15 [0091] If the Ca concentration is lower than 0.06 wt%, the strength of the negative
electrode expanded grid body is lowered. Moreover, since a potential difference between the
negative electrode and the positive electrode decreases, there is a possibility that
characteristics of electrolyte decrease are degraded. On the other hand, if the Ca
concentration is higher than 0.08 wt%, a Ca oxide is easily generated, and therefore there is a
20 possibility that a non-conductive layer is, due to a repeat of charge-discharge cycle, formed on
a surface of the negative electrode expanded grid body.
[0092] Sn Concentration
The Sn concentration in the negative electrode lead alloy sheet is preferably equal
to or higher than 0.2 wt% and equal to or lower than 1.5 wt%.
25 [0093] If the Sn concentration is lower than 0.2 wt%, there is a possibility that the
expansion cannot be performed due to lack of the strength of the lead alloy sheet. On the
other hand, if the Sn concentration is higher than 1.5 wt%, there is a possibility that Sn eluted
from the negative electrode expanded grid body is deposited on a surface of a glass mat
separator due to a repeat of deep chargingldischarging, and therefore short circuit occurs.
5 [0094] Study
Various types of study have been conducted on lead-acid batteries using expanded
grid bodies formed under various expansion conditions and each including a mesh part.
Note that shaped mesh parts were used as the mesh parts.
[0095] The configuration of the formed lead-acid batteries is as follows.
10 [0096] A control valve-type lead-acid battery was used as the lead-acid battery. The rated
voltage of the control valve-type lead-acid battery was 12V, and a nominal 20-hour rate
capacity was 7.2 Ah.
[0097] The number of cells was six. The number of positive electrode plates per cell was
four, and the number of negative electrode plates per cell was five.
15 [0098] The positive electrode plate was formed as follows. A mesh part of a positive
electrode expanded grid body was filled with an active material paste formed by mixing lead
powder, a lead oxide, and sulfuric acid together, and then was cut so as to have predetermined
electrode plate dimensions. Subsequently, maturing and drying were performed.
[0099] The negative electrode plate was formed as follows. A mesh part of a negative
20 electrode expanded grid body was filled with an active material paste formed by mixing lead
powder, a lead oxide, sulfuric acid, and an additive such as carbon and barium sulfate
together, and then was cut so as to have predetermined electrode plate dimensions.
Subsequently, maturing and drying were performed.
[0 1001 The control valve-type lead-acid battery was formed as follows.
25 [0101] An electrode plate group was formed using four positive electrode plates, five
negative electrode plates, and a glass mat separator. Then, current collectors of the electrode
plates having the same polarity were welded together with a lead alloy component.
[0102] Subsequently, a plurality of electrode plate groups were inserted into a battery
container such that adjacent ones of the electrode plate groups are arranged so as to sandwich
5 a partition. The battery container includes the partition(s) configured to divide between
adjacent ones of cells. Then, adjacent ones of the electrode plate groups arranged so as to
sandwich the partition were welded together such that the electrode plate groups form a series
circuit. Subsequently, a lid was bonded to an upper part of the battery container with an
adhesive. A terminal configured to output power to the outside was bonded to the lead alloy
10 component.
[0103] After a predetermined amount of diluted sulfuric acid was injected to the battery
container, current was applied. In this manner, initial charging for activating the electrode
plates was performed. The specific gravity of the diluted sulfuric acid before current
application was set such that the specific gravity of the electrolyte after current application
15 reaches 1.35 glml. After current application, a control valve openinglclosing with
predetermined pressure and made of rubber was attached to a liquid port. Then, an upper
part of the control valve was welded using a sealing plate.
[0104]
Study has been conducted on a relationship between the height of an intersection
20 and the amount of active material detached from an expanded grid body (see
described later).
[0105] Study has been conducted on a relationship between the width of the intersection
and the amount of detached active material (see described later).
[O106] Study has been conducted on a relationship between a ratio t2ltl of a thickness t2 of
25 an electrode plate to a thickness tl of the expanded grid body and the amount of detached
active material (see described later).
[O107] A lead alloy sheet used in fornation of a mesh part of a positive electrode expanded
grid body and a mesh part of a negative electrode expanded grid body contains a calcium (Ca)
concentration of 0.07 wt% and a tin (Sn) concentration of 1.20 wt%, and part of the lead alloy
5 sheet other than Ca, Sn, and other essential substance(s) contains lead (Pb).
[0108] Study has been conducted using a trickle charge life test performed at 60°C
according to JISC 8702-1. Trickle charge was performed with a limited current of 0.36 A
and a rated voltage of 13.8 V for four months. Then, a battery was disassembled to obtain
the amount of detached active material.
10 [O109]
Study has been conducted on a relationship between the height of a stepped part and
the amount of detached active material. Such a relationship will be described with reference
to FIG. 17. FIG. 17 is a graph showing the relationship between the height ratio of the
stepped part and the amount of detached active material.
15 [0110] The height ratio of a first stepped part or a second stepped part of a positive
electrode expanded grid body was changed, whereas the width ratio of the first stepped part or
the second stepped part was constant (specifically 10%). On the other hand, a conventional
expanded grid body was used as a negative electrode expanded grid body.
[Ol 111 The vertical axis illustrated in FIG. 17 represents the percentage of active material
20 detached from the positive electrode expanded grid body. On the other hand, the horizontal
axis illustrated in FIG. 17 represents the height ratio (i.e., the height ratio of the first stepped
part or the second stepped part) of the stepped part of the positive electrode expanded grid
body.
[0112] The percentage (%) of detached active material was obtained as follows.
25 [0113] The battery was disassembled, and a plurality (i.e., the number of positive electrode
plates per cell x the number of cells) of positive electrode plates were taken out.
[0114] Subsequently, the percentage of detached active material was obtained for each
positive electrode plate. Specifically, after the positive electrode plate was washed with
running water for three hours, the positive electrode plate was dried at 105OC for 10 hours.
5 Then, a weight w of the positive electrode plate after drying was subtracted from a weight W
of the positive electrode plate before assembly of the battery. In this manner, the amount,
i.e., W - w, of detached active material was obtained. Subsequently, the percentage, i.e., (W
- w) / W x 100, of the amount of detached active material to the weight of the positive
electrode plate before assembly of the battery was obtained.
10 [0115] Then, for all of the positive electrode plates, the average of the percentage of
detached active material was obtained, and the obtained average was taken as the percentage
(%) of detached active material.
[0116] Note that the amount of detached active material also includes the amount of active
material detached from the positive electrode expanded grid body due to disconnection, which
15 is caused by oxidation corrosion, of a mesh part of the positive electrode expanded grid body.
[0117] In order not to detach the active material which still has adhesion to the positive
electrode expanded grid body, caution was exercised particularly upon washing and drying.
[0118] In the present specification, the "height ratio of the stepped part" means the ratio of
the height (see "H6c" in FIG. 7(a)) of the first stepped part or the height (see "H6d in FIG.
20 7(a)) of the second stepped part to the thickness (see "W6a" and "W6b" in FIG. 7(a)) of the
lead alloy sheet. Note that the height of the first stepped part and the height of the second
stepped part are substantially equal to each other (H6c = H6d).
[O 1 191 [First Expression]
Height Ratio of Stepped Part(%) =
Height of First Stepped Part (or Height of Second Stepped Part)
x 100
Thickness of Lead Alloy Sheet
[O120] In the present specification, the "width ratio of the stepped part" means the ratio of
the width (see "W6cx" in FIG. 7(b)) of the first stepped part or the width of the second
stepped part to the length (see "L5" in FIG. 5(a)) of a grid bar. Note that the width of the
5 first stepped part and the width of the second stepped part are substantially equal to each
other.
[O 12 11 [Second Expression]
Width Ratio of Stepped Part (%) =
Width of First Stepped Part (or Width of Second Stepped Part)
x 100
Length of Grid Bar
[0122] Lines A, B, C, D, and E illustrated in FIG. 17 each represent the relationship
10 between the height ratio of the stepped part and the percentage of detached active material,
and correspond respectively to a lead alloy sheet thickness of 0.6 mm, 0.8 mm, 1.0 mm, 1.2
rnrn, and 1.8 mm.
[0123] The percentage of detached active material when the height ratio of the stepped part
is 0% corresponds to the percentage of detached active material when the conventional
15 expanded grid body is used as the positive electrode expanded grid body.
[(I1241 The lines A-E illustrated in FIG. 17 show that the percentage of detached active
material is low when the height ratio of the stepped part is equal to or higher than 5% and
equal to or lower than 40%.
[0125] On the other hand, when the height ratio of the stepped part is higher than 40%, the
20 percentage of detached active material increases as indicated by the lines A-E illustrated in
FIG. 17. This is because of the following reasons. When the height ratio of the stepped
part is higher than 40%, a thin part(s) having a thickness less than that of the lead alloy sheet
24 P639793
is formed at an intersection(s). Accordingly, the strength of the mesh part of the positive
electrode expanded grid body is lowered, and disconnection of the mesh part of the positive
electrode expanded grid body is likely to occur due to oxidation corrosion. As a result, the
percentage of detached active material increases.
5 [0126] The lines A-E illustrated in FIG. 17 show that the percentage of detached active
material increases when the height ratio of the stepped part is lower than 5%.
[0127] As will be seen from FIG. 17, the height of the first stepped part or the second
stepped part is preferably equal to or higher than 5% and equal to or lower than 40% with
respect to the thickness of the lead alloy sheet.
10 [0128] The percentage (i.e., the percentage of detached active material when the height
ratio of the stepped part is 0%) of detached active material when the conventional expanded
grid body is used as the positive electrode expanded grid body increases, as indicated by the
lines A-E illustrated in FIG. 17, with increasing the thickness of the lead alloy sheet. This is
because of the following reasons. A width W36z illustrated in FIG. 13(b) corresponds to the
15 thickness of the lead alloy sheet. An increase in width W36z (i.e., an increase in thickness
of the lead alloy sheet) results in an increase in volume of a gap 37 illustrated in FIG. 14.
Accordingly, the percentage of detached active material increases.
[0129] In the case where a mesh part of an expanded grid body is formed not by the
reciprocal expansion but by rotary expansion, stepped parts are formed, but the height ratio of
20 the stepped part is equal to or higher than 50% due to characteristics of the rotary expansion.
Thus, the advantages of the present disclosure cannot be realized.
[O 1301
Study has been conducted on a relationship between the width of a stepped part and
the amount of detached active material. Such a relationship will be described with reference
25 to FIG. 18. FIG. 18 is a graph showing the relationship between the width ratio of the
stepped part and the percentage of detached active material.
[0131] The width ratio of a first stepped part or a second stepped part of a positive
electrode expanded grid body was changed, whereas the height ratio of the first stepped part
or the second stepped part was constant (specifically 20%). On the other hand, a
5 conventional expanded grid body was used as a negative electrode expanded grid body.
[0132] The vertical axis illustrated in FIG. 18 represents the percentage of active material
detached from the positive electrode expanded grid body. On the other hand, the horizontal
axis illustrated in FIG. 18 represents the width ratio (i.e., the width ratio of the first stepped
part or the second stepped part) of the stepped part of the positive electrode expanded grid
10 body.
[0133] Lines A, B, C, D, and E illustrated in FIG. 18 each represent the relationship
between the width ratio of the stepped part and the percentage of detached active material,
and correspond respectively to a lead alloy sheet thickness of 0.6 mm, 0.8 mm, 1.0 mm, 1.2
mm, and 1.8 mm.
15 [0134] The percentage of detached active material when the width ratio of the stepped part
is 0% corresponds to the percentage of detached active material when the conventional
expanded grid body is used as the positive electrode expanded grid body.
[0135] The lines A-E illustrated in FIG. 18 show that the percentage of detached active
material is low when the width ratio of the stepped part is equal to or higher than 5% and
20 equal to or lower than 30%. According to observation of the positive electrode expanded
grid body when the width ratio of the stepped part is equal to or higher than 5% and equal to
or lower than 30%, the amount of deformation of the positive electrode expanded grid body
was small.
[0136] On the other hand, when the width ratio of the stepped part is lower than 5%, the
25 percentage of detached active material increases as indicated by the lines A-E illustrated in
FIG. 18. This is because of the following reasons. Since disconnection of a mesh part of
the positive electrode expanded grid body occurs due to oxidation corrosion, the percentage of
detached active material increases.
[0137] The lines A-E illustrated in FIG. 18 show that the percentage of detached active
5 material increases when the width ratio of the stepped part is higher than 30%. According to
observation of the positive electrode expanded grid body when the width ratio of the stepped
part is higher than 30%, the amount of deformation of the positive electrode expanded grid
body was small. However, the percentage of detached active material increases. This is
because of the following reasons. An increase in width (see "W6cx" in FIG. 7(b)) of the
10 stepped part results in an increase in width (see "W6cy7' in FIG. 7(a)) of the stepped part.
Thus, adhesion between the positive electrode expanded grid body and the active material is
lowered, resulting in an increase in percentage of detached active material.
[0138] Particularly in the case where the width ratio of the stepped part is higher than
32.5%, an increase in thickness of a lead alloy sheet results in an increase in percentage of
15 detached active material. This is because of the following reasons. An increase in
thickness of the lead alloy sheet results in an increase in width (see "W6cy" in FIG. 7(a)) of
the stepped part. Thus, the percentage of detached active material increases.
[(I1391 As will be seen fi-om FIG. 18, the width of the first stepped part or the second
stepped part is preferably equal to or higher than 5% and equal to or lower than 30% with
20 respect to the length of a grid bar.
[0 1401
Study has been conducted on a relationship between a ratio t2ltl of a thickness t2 of
an electrode plate to a thickness tl of an expanded grid body and the amount of detached
active material. Such a relationship will be described with reference to FIG. 19. FIG. 19 is
25 a graph showing the relationship between the ratio t2ltl and the percentage of detached active
material.
[0141] A thickness tl of a positive electrode expanded grid body was changed, whereas a
thickness t2 of a positive electrode plate was constant. Moreover, the height ratio of a first
stepped part or a second stepped part of the positive electrode expanded grid body was
5 constant (specifically 20%). Further, the width ratio of the first stepped part or the second
stepped part of the positive electrode expanded grid body was constant (specifically 30%).
[0142] The thickness of a negative electrode expanded grid body and the thickness of a
negative electrode plate were not changed, and a conventional expanded grid body was used
as the negative electrode expanded grid body.
10 [0143] The vertical axis illustrated in FIG. 19 represents the percentage of active material
detached from the positive electrode expanded grid body. On the other hand, the horizontal
axis illustrated in FIG. 19 represents the ratio t2ltl of the thickness t2 of the positive electrode
plate to the thickness t 1 of the positive electrode expanded grid body.
[0144] In the present specification, the "thckness tl of the expanded grid body"
15 corresponds to a thickness tl illustrated in FIG. 5(b). The "thickness t2 of the electrode
plate" corresponds to a thickness after the expanded grid body is filled with an active
material.
[(I1451 Referring to FIG. 19, when the ratio t2lt 1 is 1.10, the percentage of detached active
material is the lowest. When the ratio t2ltl is equal to or higher than 1.10, the percentage of
20 detached active material increases with increasing the ratio t2ltl.
[0146] From FIGS. 17 and 18, it is expected that the advantages of the present disclosure
can be realized when the percentage of detached active material is equal to or lower than 30%.
Referring to FIG. 19, when the ratio t2ltl is equal to or lower than 1.8, the percentage of
detached active material is equal to or lower than 30%. Thus, the ratio t2/tl is preferably
25 equal to or lower than 1.8.
[0147] Referring to FIG. 19, when the ratio t2ltl is lower than 1.10, the percentage of
detached active material is low. However, according to observation of the positive electrode
expanded grid body when the ratio t2ltl is lower than 1 .lo, many cracks were formed
between the positive electrode expanded grid body and the active material. Thus, the ratio
5 t2ltl is preferably equal to or higher than 1.10.
[0148] According to the foregoing, the ratio t2ltl of the thickness t2 of the electrode plate
to the thickness tl of the expanded grid body is preferably equal to or higher than 1.10 and
equal to or lower than 1.80.
[O149]
10 Study has been conducted on a relationship among a set value for bottom dead point
of an expanding blade, the length and angle of an end part of the expanding blade, and the
number of life cycles. Such a relationship will be described with reference to Table 1.
[0150] A lead alloy sheet used in formation of a mesh part of a positive electrode expanded
grid body and a mesh part of a negative electrode expanded grid body contains a Ca
15 concentration of 0.07 wt% and a Sn concentration of 1.20 wt%, and part of the lead alloy
sheet other than Ca, Sn, and other essential substance(s) contains Pb. The thickness of the
lead alloy sheet is 1.0 mm.
[(I1511 Various expanding blades (see A, B1-B5, and C1-C3 in Table 1) formed such that
the height ratio of a first stepped part or a second stepped part of the positive electrode
20 expanded grid body is 20% and that the width ratio of the first stepped part or the second
stepped part of the positive electrode expanded grid body is 10% were used as the expanding
blade used in formation of the mesh part of the positive electrode expanded grid body.
[0152] On the other hand, a conventional expanding blade was used as the expanding blade
used in formation of the mesh part of the negative electrode expanded grid body.
25 [0153] Study has been conducted using a cycle life test according to JISC 8702-1. An
environmental temperature was 25"C, and a single cycle included two-hour discharging with
a rated current of 1.8 A and six-hour charging with a rated current of 1.44 A. Discharging
was, every 50 cycles, performed with a discharge current of 0.36 A until a battery voltage
reaches 10.6 V, and then a 20-hour rate capacity was obtained. The chargeldischarge cycle
5 was terminated when the 20-hour rate capacity reached equal to or lower than 50%. Then,
the number of life cycles was calculated according to the JIS standard. In the case where the
voltage reached equal to or lower than 9.9 V during discharging, the chargeldischarge cycle
was stopped, and the 20-hour rate capacity after complete charging was obtained. If the 20-
hour rate capacity is equal to or lower than 50%, it was determined as a life limit. Then, the
10 number of life cycles was calculated according to the JIS standard.
[0154] The type of expanding blade used in formation of the mesh part of the positive
electrode expanded grid body, the set ratio for bottom dead point of the expanding blade, the
length ratio of the end part of the expanding blade, the angle of the end part of the expanding
blade, the height ratio of the first stepped part (or the second stepped part), the width ratio of
15 the first stepped part (or the second stepped part), a processing state, and the number of life
cycles are shown in Table 1 below.
[0155] [Tablel]
Expanding Blade Stepped Part
Type
X
A
B1
B2
B 3
B4
B 5
C 1
C2
C3
C4
Processing
State
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Not
Acceptable
Length
Ratio
of End
Part
(%I
0
0
5
10
15
20
25
15
15
15
15
Height
Ratio
(%I
0
20
20
20
20
20
20
20
20
20
-
Set Ratio
for
Bottom
Dead
Point
(%)
0
20
15
13
11
8
4
10
8
3
0
The Number
of Life Cycles
(The Number
of Times)
378
408
41 0
41 2
41 6
41 8
41 9
41 7
42 5
429
-
Angle of
End Part
(" >
0
0
0
0
0
0
0
2
5
10
15
Width
Ratio
(%I
0
10
10
10
10
10
10
10
10
10
-
[0156] In Table 1, " X indicates the conventional expanding blade. Moreover, "A"
indicates an expanding blade illustrated in FIG. 3(a). Further, "Bl" - "B5" indicate
expanding blades illustrated in FIG. 3(b), and "Cl" - "C4" indicate expanding blades
illustrated in FIG. 3(c).
5 [0157] In Table 1, the "set ratio for bottom dead point" indicates the ratio of the amount of
change in set value to the thickness of the lead alloy sheet. The amount of change in set
value is obtained by subtracting the set value for bottom dead point of the conventional
expanding blade fiom the set value for bottom dead point of the expanding blade (i.e., the
expanding blade of the present disclosure) illustrated in FIGS. 3(a)-3(c).
10 [O 1581 [Third Expression]
Set Ratio for Bottom Dead Point=
Set Value for Bottom Dead Point of Expanding Blade of the Present Disclosure
-Set Value for Bottom Dead Point of Conventional Expanding Blade
XI00
Thickness of Lead Alloy Sheet
[O 1591 In Table 1, the "length ratio of the end part" indicates the ratio of the length of the
end part to the length of a body. The length of the body is represented by "L9a7' in FIGS.
20(a) and 20(b). The length of the end part is represented by "L9b" in FIG. 20(a) and "L9c"
15 in FIG. 20(b).
[0 1601 [Fourth Expression]
Length of End Part
Length Ratio of End Part= X 100
Length of Body
[0161] In Table 1, the "angle of the end part" indicates the inclination angle of a lower
surface of the end part relative to a lower surface of the body, and is represented by "A" in
20 FIG. 20(b).
[0 1621 As will be seen from Table 1, the number of life cycles is low in the case where the
conventional expanding blade X is used. On the other hand, the number of life cycles is
32 P639793
high in the case where any of the expanding blades A, B1-B5, and C1-C3 is used.
[0163] After a battery including the positive electrode expanded grid body formed using
the conventional expanding blade X reached the life limit thereof, the battery was
disassembled. According to observation of such a positive electrode expanded grid body,
5 the positive electrode expanded grid body was greatly deformed in an up direction (i.e., an
upward direction in the plane of paper of FIG. 12(a)). Thus, short circuit occurs between the
positive electrode expanded grid body and a lead alloy component for negative electrode. It
is considered that such short circuit determines a battery life.
[0164] On the other hand, after a battery including the positive electrode expanded grid
10 body formed using any of the expanding blades A, B 1-B5, and C1-C3 reached the life limit
thereof, the battery was disassembled. According to observation of such a positive electrode
expanded grid body, the positive electrode expanded grid body was only slightly deformed in
an up direction (i.e., an upward direction in the plane of paper of FIG. 5(a)), and was not
greatly deformed in the up direction.
15 [(I1651 According to observation of the positive electrode expanded grid body formed
using any of the expanding blades A, B1-B5, and C1-C3, the mesh part of the positive
electrode expanded grid body was disconnected at an intersection(s) thereof due to oxidation
corrosion. Moreover, a small amount of active material was detached. A capacity is
decreased due to disconnection and detachment of a small amount of active material. It is
20 considered that such a decrease in capacity determines the battery life.
[0 1661 Expanding Blades B 1 -B5
As will be seen from Table 1, an increase in length ratio of the end part of any of
the expanding blades B1-B5 results in a decrease in set ratio for bottom dead point of the any
of the expanding blade B1-B5. This shows that the set value for bottom dead point of the
25 expanding blade decreases with increasing the length of the end part of the expanding blade.
[O167] As will be seen from Table 1, a decrease in set ratio for bottom dead point of any of
the expanding blade B 1-B5 results in an increase in number of life cycles. This is because of
the following reasons. Stress applied to the intersection upon expansion decreases with
decreasing the set ratio for bottom dead point of the expanding blade. Thus, the amount of
5 oxidation corrosion of the mesh part of the positive electrode expanded grid body can be
decreased, and the number of life cycles increases accordingly.
[O168] After a battery including the positive electrode expanded grid body formed using
any of the expanding blades B1-B5 reached the life limit thereof, the battery was
disassembled. According to observation of such a positive electrode expanded grid body,
10 the amount of deformation of the positive electrode expanded grid body in the up direction
decreases with increasing the length of the end part.
[O169] The length ratio of the end part is preferably equal to or lower than 25% so that
adjacent ones of the expanding blades do not contact each other.
[0 1701 Expanding Blades C 1 -C3
15 As will be seen from Table 1, an increase in angle of the end part of any of the
expanding blades C1-C3 results in a decrease in set ratio for bottom dead point of the any of
the expanding blade C1-C3. This shows that the set value for bottom dead point of the
expanding blade decreases with increasing the angle of the end part of the expanding blade.
[0171] As will be seen from Table 1, a decrease in set ratio for bottom dead point of any of
20 the expanding blade C1-C3 results in an increase in number of life cycles. Thls is because of
the same reasons as those described above (see "Expanding Blades B1-B5").
[O172] In the case where the angle of the end part is greater than 10" (see the expanding
blade C4), the height ratio of the stepped part is higher than 20%. After a battery including
the positive electrode expanded grid body formed using the expanding blade C4 reached the
25 life limit thereof, the battery was disassembled. According to observation of such a positive
electrode expanded grid body, the mesh part thereof was disconnected. Thus, the angle of
the end part is preferably equal to or less than 10".
[0173] Comparison between Expanding Blade C3 and Each of Expanding Blades C1-C3
As will be seen from Table 1, in the case where any of the expanding blades C1-C3
5 (having an end part length ratio of 15%) is used, the set ratio for bottom dead point is lower,
and the number of life cycles is higher as compared to the case where the expanding blade B3
(having an end part length ratio of 15%) is used. This shows as follows. Any of the
expanding blade C1-C3 formed such that the lower surface of the end part is inclined relative
to the lower surface of the body allows the set ratio for bottom dead point to be lower than
10 that in the case where the expanding blade B3 formed such that the lower surface of the end
part is not inclined relative to the lower surface of the body is used. Thus, the number of life
cycles increases.
[0 1741
Study has been conducted on the number of life cycles in the case where the
15 expanded grid body of the present variation is used as at least one of a positive electrode
expanded grid body or a negative electrode expanded body.
[0175] Table 2 shows the case where a conventional expanding blade X or an expanding
blade A of the present disclosure is used as an expanding blade for positive electrode used in
formation of a mesh part of the positive electrode expanded grid body, and the conventional
20 expanding blade X or the expanding blade A of the present disclosure is used as an expanding
blade for negative electrode used in formation of a mesh part of the negative electrode
expanded grid body.
[0176] Table 3 shows the case where the conventional expanding blade X or an expanding
blade B3 of the present disclosure is used as the positive electrode expanding blade, and the
25 conventional expanding blade X or the expanding blade B3 of the present disclosure is used
35 P639793
as the negative electrode expanding blade.
[O177] Table 4 shows the case where the conventional expanding blade X or an expanding
blade C3 of the present disclosure is used as the positive electrode expanding blade, and the
conventional expanding blade X or the expanding blade C3 of the present disclosure is used
5 as the negative electrode expanding blade.
[0178] The thickness of a positive electrode lead alloy sheet is 1.0 mm. On the other
hand, the thickness of a negative electrode lead alloy sheet is 0.7 mm.
[O 1791 Study has been conducted using a cycle life test according to JISC 8702-1. The
method for calculating the number of life cycles is the same as the life cycle calculation
10 method described in .
[0180] The type of positive electrode expanding blade, the Ca concentration and the Sn
concentration of the positive electrode lead alloy sheet, the height ratio and the width ratio of
a stepped part of the positive electrode expanded grid body, the type of negative electrode
expanding blade, the Ca concentration and the Sn concentration of the negative electrode lead
15 alloy sheet, the height ratio and the width ratio of a stepped part of the negative electrode
expanded grid body, and the number of life cycles are shown in Tables 2,3, and 4.
[O 18 11 [Table 21
The Number
of Life Cycles
(The Number
of Times)
378
41 6
438
407
442
No.1
No.6
No.7
No.8
No.9
Positive Electrode Negative Electrode
Type of
Expanding
Blade
X
X
63
63
X
Type of
Expanding
Blade
X
B3
83
X
B3
Stepped Part Lead Alloy Sheet Stepped Part
Height
Ratio
(%I
0
0
20
20
0
Lead Alloy Sheet
Height
Ratio
(96)
0
20
20
0
20
Ca
Concentration
(wt%)
0.07
0.07
0.07
0.07
0.07
Width
Ratio
(%I
-
-
10
10
-
Ca
Concentration
(wt%)
0.07
0.07
0.07
0.07
0.07
-
Width
Ratio
(%)
-
10
10
-
10
Sn
Concentration
(wt%)
0.3
0.3
0.3
0.3
0.3
Sn
Concentration
(wt%)
1.2
1.2
1.2
1.2
1.6
The Number
of Life Cycles
(The Number
of Times)
378
429
461
412
458
No.1
No.10
No.11
No.12
Positive Electrode Negative Electrode
Type of
Expanding
Blade
X
X
C3
C3
No.13 C3 20 10 X -
Type of
Expanding
Blade
X
C3
C3
X
Stepped Part
0
Lead Alloy Sheet
0.07
Height
Ratio
(%I
0
0
20
20
-
Ca
Concentration
(wt%)
0.07
0.07
0.07
0.07
0.3
Width
Ratio
(%)
-
-
10
10
Lead Alloy Sheet
Sn
Concentration
(wt%)
0.3
0.3
0.3
0.3
Ca
Concentration
(wt%)
0.07
0.07
0.07
0.07
Stepped Part
Sn
Concentration
(wt%)
1.2
1.2
1.2
1.2
Height
Ratio
(%)
0
20
20
0
Width
Ratio
(%)
-
10
10
-
[O184] As will be seen from Table 2, second to fifth batteries (i.e., batteries each using the
expanded grid body of the present variation as at least one of the positive electrode expanded
grid body or the negative electrode expanded grid body) have a higher number of life cycles
than that of a first battery (i.e., a battery using a conventional expanded grid bodies as the
5 positive electrode expanded grid body and the negative electrode expanded grid body).
[0185] Similarly, Table 3 shows that sixth to ninth batteries (i.e., batteries each using the
expanded grid body of the present variation as at least one of the positive electrode expanded
grid body or the negative electrode expanded grid body) have a higher number of life cycles
than that of the first battery.
10 [O186] Similarly, Table 4 shows that tenth to thirteenth batteries (i.e., batteries each using
the expanded grid body of the present variation as at least one of the positive electrode
expanded grid body or the negative electrode expanded grid body) have a higher number of
life cycles than that of the first battery.
[O187] As will be seen from Tables 2, 3, and 4, the number of life cycles increases in such
15 a manner that the expanded grid body of the present variation is used as at least one of the
positive electrode expanded grid body or the negative electrode expanded grid body.
INDUSTRIAL APPLICABILITY
[0188] According to the present disclosure, adhesion between the mesh part of the
20 expanded grid body and the active material can be enhanced. The present disclosure is
useful for an expanded grid body, a method for manufacturing the expanded grid body, and an
electrode plate and a lead-acid battery using the expanded grid body.
DESCRIPTION OF REFERENCE CHARACTERS
25 [0189]
1 la, 1 lb
Expanded Grid Body
Mesh Part
Grid Frame
Current Collector Ear Part
Grid Bar
Intersection
First Part
Second Part
First Stepped Part
Second Stepped Part
Gap
Cutting Blade
Expanding Blade
Body
End Part
Part
Part
Part
Cutting Die
Cutting Blade
Expanding Die
Expanding Blade
Sheet
Line
Shaded Part
Expanded Grid Body
Mesh Part
Grid Frame
Current Collector Ear Part
Grid Bar
Intersection
First Part
Second Part
Gap
Part
We Claim: -
1. An expanded grid body comprising:
a mesh part formed by reciprocal expansion,
wherein the mesh part is formed in such a manner that, while a sheet is being
intermittently fed between a cutting die including a cutting blade and an expanding die
including an expanding blade, the expanding die reciprocates up and down to form a slit in
the sheet and to downwardly expand part of the sheet contacting the expanding blade,
the mesh part includes a grid bar and an intersection,
the intersection includes a first part and a second part, and
the first and second parts are arranged such that contact surfaces thereof are
displaced from each other in an up-down direction.
2. An expanded grid body comprising:
15 a mesh part formed by reciprocal expansion,
wherein the mesh part is formed in such a manner that, while a sheet is being
intermittently fed between a cutting die including a cutting blade and an expanding die
including an expanding blade, the expanding die reciprocates up and down to form a slit in
the sheet and to downwardly expand part of the sheet contacting the expanding blade, and
20 then is pressed and shaped in such a manner that the mesh part is fed between rollers,
the mesh part includes a grid bar and an intersection,
the intersection includes a first part, a second part, a first stepped part, and a second
stepped part,
the first and second parts are arranged such that contact surfaces thereof are
25 displaced from each other in an up-down direction and overlap with each other as viewed in a
pressing direction,
the first and second stepped parts are formed in such a manner that the first and
second parts overlap with each other as viewed in the pressing direction, and
the grid bar interposed between the first and second parts is curved relative to the
5 first and second parts.
3. The expanded grid body of claim 2, wherein
a height of the first stepped part and a height of the second stepped part are each
equal to or higher than 5% and equal to or lower than 40% with respect to a thickness of the
10 sheet.
4. The expanded grid body of claim 2, wherein
a width of the first stepped part and a width of the second stepped part are each
equal to or higher than 5% and equal to or lower than 30% with respect to a length of the grid
15 bar.
5. An electrode plate comprising:
the expanded grid body of claim 2,
wherein a ratio t21tl of a thickness t2 of the electrode plate to a thickness tl of the
20 expanded grid body is equal to or higher than 1.10 and equal to or lower than 1 .SO.
6. A lead-acid battery comprising:
the expanded grid body of any one of claims 1-4.
7. A method for manufacturing an expanded grid body including a mesh part
44
formed by reciprocal expansion, the method comprising:
a step (a) of forming the mesh part in such a manner, while a sheet is being
intermittently fed between a cutting die including a cutting blade and an expanding die
including an expanding blade, the expanding die reciprocates up and down to form a slit in
5 the sheet and to downwardly expand part of the sheet contacting the expanding blade,
wherein the mesh part includes a grid bar and an intersection,
the intersection includes
a first part having a part which comes into contact with a tip end of the
expanding blade, and
10 a second part having a part which comes into contact with an end of the
expanding blade, and
the first and second parts are arranged such that contact surfaces thereof are
displaced from each other in an up-down direction
8. The method of claim 7, further comprising:
a step (b) of pressing and shaping, after the step(a), the mesh part in such a manner
that the mesh part is fed between rollers,
wherein, at the step (b), a first stepped part and a second stepped part are formed in
such a manner that the first and second parts overlap with each other as viewed in a pressing
direction,
the intersection further includes the first and second stepped parts, and
the grid bar interposed between the first and second parts is curved relative to the
first and second parts.
9. The method of claim 7, wherein
45
the expanding blade includes a body and an end part connected to an end of the
body, and
a length of the end part is equal to or lower than 25% with respect to a length of the
body.
5
10. The method of claim 7, wherein
the expanding blade includes a body and an end part connected to an end of the
body, and
an inclination angle of a lower surface of the end part relative to a lower surface of
10 the body is equal to or less than 10".