DESCRIPTION
BATTERY ELECTRODE PLATE, MANUFACTURING METHOD FOR SAME,
5 ELECTRODE PLATE GROUP HAVING SAID ELECTRODE PLATE, AND LEAD-ACID
BATTERY
TECHNICAL FIELD
[0001]
10 The present invention relates to battery electrode plates and methods of
manufacturing the electrode plates. Specifically, the present invention relates to battery
electrode plates, which are simply processible at low costs and have large capacity, long cycle
lives, and great charge efficiency, and methods of manufacturing the electrode plates,
electrode plate groups including the electrode plates, and lead storage batteries.
15
BACKGROUND ART
[0002]
In addition to starting and backup power supplies of vehicles, lead storage batteries
are widely used as main power supplies, specifically, for example, power supplies of
20 independently charged and discharged systems such as power sources of electric vehicles,
electric bicycles, electric motorcycles, electric motor scooters, small electric motorcycles, golf
carts, etc., as well as solar energy batteries. In this usage, lead storage batteries have
operational characteristics such as large starting currents, small discharge currents in traveling
vehicles, and long discharge times. At the same time, reducing the maintenance of the lead
25 storage batteries is demanded. Extending the cycle lives is particularly demanded. For
longer lives of the batteries, usually, the pressure applied to electrode plate groups is
2
increased, and positive electrode active materials are pressed by separators, thereby reducing
expansion of the positive electrode active materials to reduce fall-off of the positive electrode
active materials. However, with an increase in the sizes of the batteries, it becomes difficult
to keep applying appropriate pressure to the electrode plate groups even by changing the
5 materials of the battery containers and increasing the thicknesses of the battery containers to
reinforce the battery containers. With an increase in the period of use, positive electrode
current collectors are oxidized to corrode the lead storage batteries. This reduces the crosssectional
areas of the positive electrode current collectors to deteriorate the conductivity of
the positive electrode plates. As a result, voltage profiles deteriorate when the batteries are
10 discharged at a high rate. If such corrosion of the positive electrode current collectors
further proceeds, the positive electrode current collectors themselves eventually break. This
rapidly lowers the battery capacity to end the lives.
[0003]
Repetitive charge and discharge in use of the lead storage batteries gradually
15 degrade the battery performance. If the battery performance degrades, the internal pressure
of the batteries rises to apply great pressure between the positive electrode plates and the
negative electrode plates. At this time, the electrode groups are subject to compression or
deformation. That is, the electrode groups tend to be easily crushed when the internal
pressure of the batteries rises.
20 [0004]
On the other hand, with rapid development in reducing the sizes and weights of
electronic devices, lead storage batteries as power supplies are required to reduce the volume
and increase the charge and discharge capacity. It is an effective means for reducing the
volume without changing the capacity to reduce the distance between positive and negative
25 electrode plates of batteries. However, if the positive and negative electrode plates are too
o
J
close, there is a risk of causing an internal short circuit. If a positive electrode plate is shortcircuited
with a negative electrode plate, the temperature inside a battery rises. An electrode
plate group needs to have a function to ensure the security at this time as well. In view of
maintaining the power characteristics and the charge and discharge capacity of the battery,
5 there is a need to secure the ion permeability of the electrode plate group, and absorbing and
holding capability of an electrolyte.
[0005]
How to prepare grid alloys and lead paste, etc., have been conventionally
considered in view of improving the general performance such as the cycle lives, the capacity,
10 and the charge-discharge efficiency, of lead storage batteries. The structures and the
performance of electrode plates have been variously studied, as they largely influence the
volume, the power characteristics, the charge and discharge capacity, and the cycle lives of
the lead storage batteries.
[0006]
15 Chinese Utility Model No. CN 201820837 U shows a uniformly curved pasteshielding
plate for double-side coating of an electrode plate. The objective is as follows.
Specifically, conventional paste-shielding plates have flat working surfaces at the lower ends.
When being discharged, lead paste applies constant pressure to an electrode plate. This
recesses the electrode plate downward to increase the distance between the paste-shielding
20 plate and the center of the electrode plate, thereby requiring a relatively larger amount of the
paste to be applied to the center. Before curing after the double-side coating, the electrode
plate has a greater thickness at the center and a small thickness at the both ends. After the
curing, the electrode plate curves significantly to influence the quality of the electrode plate.
The uniformly curved paste-shielding plate for double-side coating of the electrode plate
25 includes a paste-shielding plate, and a paste outlet provided in the paste-shielding plate to
4
apply the paste to the electrode plate. The paste outlet vertically penetrates the pasteshielding
plate. The working surface at the lower end of the paste-shielding plate is an arc
projecting outward. This working surface being the arc projecting outward is well balanced
with the electrode plate recessed downward by compensating the amount of the deformation
5 of the electrode plate so that the paste applied to the electrode plate has a substantially
uniform thickness to improve the quality of the product.
[0007]
Chinese Utility Model No. CN 201906687 U shows an eccentricity adjuster
controlling the thickness of an electrode plate in a coater. The eccentricity adjuster
10 randomly detects the thickness of the electrode plate during the actual operation. When
fluctuations occur, the eccentricity adjuster performs dynamic control without stopping the
coater so that the electrode plate passing through the coater has a uniform thickness.
[0008]
Japanese Patent Publication No. S57-21068 shows a method of manufacturing a
15 positive electrode for a sealed lead storage battery. The feature of this method of
manufacturing the positive electrode for the sealed lead storage battery is that active material
lead paste with a small lead paste density ranging from 3.0 to 3.4 g/cm3(the density of
conventional lead paste ranges from 3.7 to 4.1 g/cm3) fills a grid and dried. The objective of
the method is to increase the porosity of the positive electrode plate by increasing the density
20 of the paste in the positive electrode plate, thereby rapidly improving the discharge
characteristics of the sealed lead storage battery. On the other hand, the lead paste is
subjected to aqueous dispersion of polytetrafluoroethylene to reduce shortening of the life
caused by the reduced density of the lead paste.
[0009]
25 Japanese Patent Publication No. S58-223259 shows a method of manufacturing an
5
electrode plate for a lead storage battery. The feature of the method of manufacturing the
electrode plate for the lead storage battery is that, after active material lead paste fills a bandlike
expanded grid made of lead or a lead alloy, cut portions with a small width provided al
regular intervals in the length direction are pressed, compressed, and cut at the centers to be
5 divided into individual electrode plates, and then dried. As shown in FIG. 4 of the document,
each of the electrode plates obtained by the method has a smaller thickness at the both ends
than at the center. The objective of the method is to overcome the conventional problem that
the active material has lower holding capability and are easily removed at the cut portions.
[0010]
10 Japanese Patent Publication No. 2007-258088 shows an electrode plate for a lead
storage battery, which is formed by pasting an active material to a grid body having a lug as a
collector at one end. In the electrode plate for the lead storage battery, the grid body is
formed such that the thickness gradually increases from the one end to the other end. The
active material layer is formed such that the thickness gradually decreases from the one end to
15 the other end of the grid body. As a result, the thickness of the electrode plate, which is the
sum of the thicknesses of the grid body and the active material layer covering the grid body,
are almost equal from the one end to the other end of the grid body. The electrode plate for
the lead storage battery reduces partial exposure of the grid body caused by the active material
layer covering the grid body and having a reduced thickness around the lug. This reduces
20 deterioration in the battery performance.
[0011]
Japanese Patent Publication No. 2003-86175 shows a pasted electrode plate for a
lead storage battery, which has a smooth surface without projections and recesses or thickness
variations. The pasted electrode plate, which is obtained by pasting active material lead
25 paste to a substrate and drying the paste, passes through the gap between rollers of a roll press.
6
This reduces an increase in the thickness of the pasted electrode plate to form a uniform
thickness, and smoothens the attachment or protrusions of the both surfaces of the pasted
electrode plate. The pasted electrode plate for the lead storage battery greatly reduces
problems such as a short circuit.
5 [0012]
The following is found from the foregoing. In the conventional techniques,
forming an electrode plate for a lead storage battery with a flat surface and a uniform
thickness is considered advantageous for the lead storage battery as well as in formation in
assembling and charging the battery. Thus, the designs of electrode plates have been
10 considered conventionally and some methods were found. For example, as described above,
the density of the lead paste of the positive electrode plate is reduced to increase the porosity
of the positive electrode plate, thereby improving the rapid discharge characteristics of the
sealed lead storage battery. However, a decrease in the density of the lead paste shortens the
life of the battery. Alternatively, the electrode plate has the smaller thickness at the both
15 ends than at the center, thereby overcoming the problem that the active material has lower
holding capability and easily falls off at the ends.
[0013]
However, where the electrode plate has the flat surface and the uniform thickness, a
large amount of a sulfuric acid cannot be held for frequent chemical reaction. Thus, the
20 capacity is difficult to increase, and designed initial capacity might not be obtained. In
addition, if each electrode plate has a flat surface and a uniform thickness, the pitch between a
positive electrode plate and a negative electrode plate is too small to cause a short circuit,
which influences the cycle life. Since the electrode plate is too flat and a separator is too
close to the electrode plate, oxygen gas generated in the positive electrode plate at a terminal
25 stage of the discharge cannot be diffused to the negative electrode immediately. This
7
influences recombination of the oxygen gas to reduce the charge efficiency.
[0014]
As such, conventionally, various studies have been made on the structures and the
performance of electrode plates. However, no one have considered how to form a lead
5 storage battery with a long cycle life, excellent capacity characteristics, and great charge
efficiency by designing the form and the structure of an electrode plate. There is a dire need
to consider this respect.
SUMMARY OF THE INVENTION
10 TECHNICAL PROBLEM
[0015]
It is an objective of the present invention to provide a battery electrode plate, which
is simply processible at low costs and has large capacity, a long cycle life, and great charge
efficiency, and a method of manufacturing the electrode plate, an electrode plate group
15 including the electrode plate, and a lead storage battery.
SOLUTION TO THE PROBLEM
[0016]
20 In order to achieve the objective, the present invention designs an electrode plate to
have protrusions at the ends such that the electrode plate has a greater thickness at the ends
than at the other portions.
[0017]
Specifically, the present invention provides a battery electrode plate including a
25 current collector, and an active material layer supported by the current collector. The current
8
collector is an expanded grid fabricated by expansion. The battery electrode plate includes
two protruding ends, each having a protrusion, and a flat middle portion located between the
two ends. The ends have a greater thickness than the middle portion. Where the thickness
at the middle portion is H2, and a difference between the thickness at the ends and the
5 thickness at the middle portion is HI, a ratio of HI to H2 (H1/H2) ranges from 3% to 9%.
[0018]
In the battery electrode plate according to the present invention, the ratio H1/H2
preferably ranges from 4% to 8%.
[0019]
10 In the battery electrode plate according to the present invention, a width of the ends
preferably ranges from 5% to 25% of a width of the entire electrode plate, and more
preferably from 10% to 20%.
[0020]
In the battery electrode plate according to the present invention, the protrusions of
15 the two protruding ends may be formed at a same side of the battery electrode plate, or may
be formed at different sides of the battery electrode plate.
[0021]
In the battery electrode plate according to the present invention, the protrusions are
preferably formed by rotary cut in cutting into the battery electrode plate. A rotary cut bit
20 used in the rotary cut preferably has a blade angle ranging from 45° to 75°, more preferably
from 50° to 70°. The protrusions may be formed by punching in cutting into the battery
electrode plate.
[0022]
In the battery electrode plate according to the present invention, a density of the
25 active material layer, which is a density of lead paste, of the electrode plate preferably ranges
9
from 4.15 g/cm3 to 5.0 g/cm3.
[0023]
The battery electrode plate according to the present invention is preferably a
positive electrode plate. A density of the active material layer, which is a density of lead
5 paste, of the positive electrode plate preferably ranges from 4.15 g/cm3 to 4.45 g/cm .
[0024]
The present invention further provides a method of manufacturing the electrode
plate. Rotary cut is performed in cutting into the electrode plate. A rotary cut bit used in
the rotary cut has a blade angle ranging from 45° to 75°. The blade angle preferably ranges
10 from 50° to 70°.
[0025]
In the method according to the present invention, a density of the active material
layer, which is a density of lead paste, of the electrode plate preferably ranges from 4.15
g/cm3 to 5.0 g/cm3.
15 [0026]
In the method according to the present invention, the electrode plate is preferably a
positive electrode plate. A density of the active material layer, which is a density of lead
paste, of the positive electrode plate preferably ranges from 4.15 g/cm3 to 4.45 g/cm3.
[0027]
20 The present invention further provides an electrode plate group including a plurality
of positive electrode plates and a plurality of negative electrode plates, which are alternately
arranged with a separator interposed between a pair of the positive and negative electrode
plates. At least each of the positive electrode plates is the battery electrode plate according
to the present invention.
25 [0028]
10
The present invention further provides a lead storage battery including the electrode
plate group according to the present invention.
ADVANTAGES OF THE INVENTION
5 [0029]
The present invention designs the electrode plate to have protrusions at the ends
such that the electrode plate has the greater thickness at the ends than at the other portions.
This properly increases the pitch between each pair of the positive and negative electrode
plates, thereby largely reducing possibilities of a short circuit to extend the cycle life. In
10 addition, a large amount of electrolyte is held in the space between each pair of the positive
and negative electrode plates to cause chemical reaction frequently. As a result, the capacity
increases and oxygen gas generated in the positive electrode plates at a terminal stage of the
discharge is immediately diffused to the negative electrodes. This is advantageous in
recombining the oxygen gas to increase the charge efficiency.
15
BRIEF DESCRIPTION OF THE DRAWINGS
[0030]
[FIG. 1] FIG. 1 is a schematic view of a battery electrode plate according to a
first embodiment of the present invention.
20 [FIG. 2] FIG. 2 is a schematic view of a battery electrode plate according to a
second embodiment of the present invention.
[FIGS. 3] FIG. 3(a) is a schematic perspective view of the battery electrode plate
according to the first embodiment of the present invention. FIG. 3(b) is a front view of the
battery electrode plate shown in FIG. 3(a). FIG. 3(c) is a transverse sectional view of the
25 battery electrode plate shown in FIG. 3(a).
11
[FIGS. 4] FIG. 4(a) illustrates steps of manufacturing an expanded grid and an
electrode plate by expansion processing. FIG. 4(b) is an enlarged schematic view
illustrating part of the steps.
[FIG. 5] FIG. 5 is a schematic view illustrating where rotary cut is performed in
5 cutting into electrode plates according to the present invention.
[FIG. 6] FIG. 6 is a schematic view illustrating where a plurality of rotary cutters
shown in FIG. 5 are used at the same time in the rotary cut.
[FIG. 7] FIG. 7 is a schematic perspective view illustrating where punching is
performed in the cutting.
10 [FIG. 8] FIG. 8 is a front view corresponding to FIG. 7.
DESCRIPTION OF EMBODIMENTS
[0031]
The present invention will be described hereinafter with reference to the drawings.
15 For simplification, the same reference characters are used in the drawings to represent
elements having substantially the same function. The present invention is not limited to the
following embodiments.
[0032]
The present invention provides a battery electrode plate. The battery electrode
20 plate includes a current collector, and an active material layer supported by the current
collector. The current collector is an expanded grid fabricated by expansion. The electrode
plate includes two protruding ends, each of which has a protrusion, and a flat middle portion
located between the two ends. The ends have a larger thickness than the middle portion.
Where the thickness at the middle portion is H2, and a difference between the thickness at the
25 ends and the thickness at the middle portion is HI, a ratio of HI to H2, that is a ratio H1/H2,
12
preferably ranges from 3% to 9%. The thickness at the ends is the maximum thickness at the
protruding ends.
[0033]
The present invention designs each electrode plate to have the protrusions at the
5 ends such that the electrode plate has the greater thickness at the ends than at the other
portions. This properly increases the pitch between a positive electrode plate and a negative
electrode plate, thereby providing the battery electrode plate with increased capacity, a long
cycle life, and great charge efficiency. Specifically, first, a large reaction space is obtained
to hold a large amount of a sulfuric acid. Reaction continues for a long period, thereby
10 increasing the capacity. Next, since the electrode plate has the greater thickness at the both
ends, the frame of the grid at the cut portions of the both ends is distant from the surface of
the electrode plate. This reduces a short circuit caused by breaking a separator, and
strengthens the both ends to reduce growth of the grid of the electrode plate (extension of the
grid frame). As a result, the cycle life extends. In addition, since the both ends are thick, a
15 certain space can be provided between the middle portion of the electrode plate and the
separator. This is advantageous in sending out the oxygen gas in charging. Slow diffusion
of the oxygen gas and a decrease in the charge efficiency due to loss of the oxygen gas are
reduced, thereby improving the charge efficiency. When the battery is charged normally,
part of the electricity is used for reaction of lead sulfate and part of the electricity is used for
20 decomposition of water. If the oxygen gas cannot be carried to the negative electrode
immediately, the oxygen gas tends to remain, thereby causing the following two problems.
Specifically, first, the remaining oxygen gas hinders the reaction of the lead sulfate to
influence the formation efficiency. Second, the remaining oxygen gas hinders the oxygen
gas from being diffused to the negative electrode immediately to lose the oxygen gas, thereby
25 causing water loss. The above two problems reduce the charge efficiency. The charge
13
efficiency represents reactivity of lead sulfate and efficiency in circulating the oxygen gas.
[0034]
FIG. 1 is a schematic view of a battery electrode plate according to a first
embodiment of the present invention. As shown in FIG. 1, the thickness at the middle
5 portion of the electrode plate is H2, the difference between the thickness at the ends of the
electrode plate and the thickness at the middle portion is HI, the width of the ends of the
electrode plate is H3, and the width of the entire electrode plate is H4.
[0035]
In FIG. 1, respective protrusions of two protruding ends are formed at the same side
10 of the electrode plate, and are preferably formed by rotary cut in cutting, which will be
described later.
[0036]
FIG. 2 is a schematic view of a battery electrode plate according to a second
embodiment of the present invention. As shown in FIG. 2, respective protrusions of two
15 protruding ends are in different forms from the protrusions shown in FIG. 1. The respective
protrusions of the two protruding ends are formed at the different sides of the electrode plate.
The protrusions are preferably formed by punching in cutting, which will be described later.
[0037]
FIG. 3(a) is a perspective view of the battery electrode plate according to the first
20 embodiment of the present invention. FIG. 3(b) is a front view of the battery electrode plate
shown in FIG. 3(a). FIG. 3(c) is a transverse sectional view of the battery electrode plate
shown in FIG. 3(a).
[0038]
As shown in FIGS. 3(a), 3(b), and 3(c), the electrode plate includes two protruding
25 ends, each of which has a protrusion, and a flat middle portion located between the two ends.
14
The ends have a greater thickness than the middle portion. Each of the protrusions of the
two protruding ends may be a current collector and/or an active material layer supported by
the current collector. In view of simplifying the process and reducing costs, each protrusion
is preferably only an active material layer.
5 [0039]
The thickness of each protrusion is equal to the thickness difference HI. As long
as HI is within a certain range, a proper space is provided between a separator and the
electrode plate, thereby effectively increasing the charge efficiency, reducing a short circuit,
and increasing the capacity. If HI is too great, the active material at the both ends
10 excessively protrudes to increase the risk of causing the short circuit, to excessively increase
the space between each pair of the electrode plates, and to accelerate the water loss of the
battery, which is counterproductive. On the other hand, if HI is too small, the thickness
difference between the both ends and the middle portion is unclear. In addition, the charge
efficiency does effectively increase, and the growth of the grid of the electrode plate cannot
15 be effectively reduced. In view of the two problems, the ratio of HI to H2 (i.e., H1/H2)
preferably ranges from 3% to 9%, both inclusive. Where the ratio H1/H2 ranges from 3% to
9%, the battery capacity increases by about 10% to 20%, as compared to the case where the
ratio H1/H2 is 0. In view of providing greater advantages, the ratio H1/H2 more preferably
ranges from 4% to 8%, both inclusive.
20 [0040]
The forms of the protrusions are not particularly limited, as long as they have the
protruding ends. For example, the protrusions may be formed like domes, mountains, etc.
The thickness of each protrusion represents the maximum thickness at the top of the
protrusion.
25 [0041]
15
The width of the protrusions is equal to the width H3 of the ends of the electrode
plate. If H3 is too great, the protrusions are difficult to produce. In addition, since the
space between the separator and the electrode plate becomes too large, the expansion of the
active material in an electrode plate group, and fall-off of the active material cannot be
5 effectively reduced. This may shorten the cycle life of the battery. If the H3 is too small,
too little stress is applied to the both ends of the electrode plate. Then, since the growth of
the grid of the electrode plate cannot be effectively reduced, the capacity of the battery
becomes unstable, and the cycle life decreases. In view of the two problems, the ratio
H3/H4 preferably ranges from 5% to 25%, both inclusive, and more preferably from 10% to
10 20%, both inclusive.
[0042]
Each electrode plate may be a positive electrode plate or may be a negative
electrode plate, but is preferably a positive electrode plate. The reasons follow.
Specifically, in the lead storage battery, gas is generated in the positive electrode. The grid
15 of the positive electrode plate is easily grown (i.e., the grid frame expands easily) and is more
subject to a short circuit. Furthermore, since the battery capacity depends on the positive
electrode, forming protrusions in the positive electrode plate is more advantageous than in the
negative electrode plate.
[0043]
20 The respective protrusions of the two protruding ends may be formed at the same
side of the electrode plate, or may be at the different sides of the electrode plate. However,
the former is preferable. The reasons follow. Specifically, the space obtained by forming
the two protrusions at the same side of the electrode plate is larger than the space obtained by
forming the two protrusions at the different sides of the electrode plate. As a result, a larger
25 amount of the sulfuric acid remains to increase the capacity of the battery. In addition, the
16
electrode plate in this state increases the charge efficiency of the battery, and effectively
reduces run-out of the battery life in a short period. As a result, the obtained electrode plate
group and the battery using the electrode plate group provide more excellent performance.
[0044]
5 The protrusions may be formed in designing process conditions in a manufacturing
method of the electrode plate, or in designing the structure of the active material layer.
[0045]
In the manufacturing method of the electrode plate, main steps are as shown in
FIGS. 4(a) and 4(b). The method includes the following steps. In (1) expansion, a lead
10 tape 27 made of lead or a lead alloy is repeatedly punched by a reciprocating punch to from a
plurality of slits along the length of the lead tape. At the same time, the slits are expanded in
a direction perpendicular to the surface of the lead tape to form a net sheet with a net 25
including a plurality of crossed wires. In (2) shaping, the net sheet is shaped by a pair of
rollers of a shaping die to obtain an expanded grid. In (3) a lead pasting, lead paste 24a as an
15 active material fills the net 25 in the expanded grid along the length of the grid to form a lead
plate 2. In (4) cutting, the expanded grid filled with the lead paste 24a is cut to form
electrode plates, each of which has a lug 9, that is, to obtain unformed electrode plates 2a.
[0046]
After that, the unformed electrode plates 2a are cured, dried, and formed to obtain
20 electrode plates. The formation may be performed after fabricating the electrode plate group
using unformed positive and negative electrode plates, and arranging the plates in a battery
container of the lead storage battery, or may be performed before fabricating the electrode
plate group. The former is however more preferable.
[0047]
25 Each "thickness" here represents the thickness of each part, after the battery
17
becomes a finished product and before the finished battery is used.
[0048]
The respective protrusions of the two protruding ends according to the present
invention are formed at the same time as the cutting. Specifically, the protrusions may be
5 formed in designing the process conditions in the cutting. To be specific, the protrusions
may be formed by rotary cut in the cutting, or may be formed by punching in the cutting.
[0049]
FIG. 5 is a schematic view illustrating the case where the rotary cut is performed in
the cutting. As shown in FIG. 5, a rotary cutter used in the rotary cut includes a rotary cut
10 bit 5 and a support roller 4. The rotary cut bit 5 includes a roller 3 and blades 5a formed in
the roller 3 at regular intervals. In the cutting, as indicated by the arrow of FIG. 5, the rotary
cut bit 5 and support roller 4 rotate around the centers of the respective rollers such that the
lead plate 2 (i.e., an electrode plate base material formed by pasting the lead paste 24a to the
expanded grid) passing therebetween receives the cutting force of the blades 5a of the rotary
15 cut bit 5 and the bearing power of the support roller 4. As a result, the lead plate 2 is cut into
electrode plates 2a. Specifically, the lead plate 2 is carried at constant speed along the cutter.
The rotary cut bit 5 rotates above the lead plate 2 at the speed according to the speed of the
lead plate 2 so that the rotating blades 5a cut the lead plate 2 at certain distances. As a result,
the electrode plates 2a are obtained. At the same time, the blade pushes away the active
20 material in the cutting, thereby forming the protrusions 6 at the both ends of the electrode
plates 2a. While in FIG. 5, an example has been described where the single rotary cutter is
used to perform the rotary cut, a plurality of rotary cutters may be actually used at the same
time. The number of the rotary cutters is determined as appropriate in accordance with the
balance with the carrying speed of the expanded grid and the rotation speed of the rotary cut
25 bit 5, the needed sizes of the electrode plates, etc. FIG. 6 is a schematic view illustrating the
18
case where a plurality of rotary cutters shown in FIG. 5 are used at the same time in the rotary
cut. The thickness of each protrusion 6 is related to the angle of the blades 5a. Thus, the
thickness HI of the protrusions eventually formed at the both ends of the electrode plate in the
present invention is related to the angle a of the blades 5a. The blade angle a need to be
5 controlled so that the thickness HI of the protrusions falls within a range required in the
present invention. The blade angle a preferably ranges from 45° to 75°, both inclusive, and
more preferably ranges from 50° to 70°, both inclusive.
[0050]
The rotary cut has the following features. Specifically, the forward speed of the
10 lead plate is well controllable, and the rotation speed of the rotary cut bit is easily controlled
in synchronization with the speed of the lead plate. As a result, large-size electrode plates
(e.g., ranging from 64 mm to 140 mm) can be produced. In addition, the processing speed
and the space between the rotary cut bit and the support roller are controlled, thereby
controlling the thickness of the electrode plate and the thickness of each protrusion.
15 [0051]
FIG. 7 is a schematic perspective view illustrating the case where punching is
performed in the cutting. FIG. 8 is a front view of corresponding to FIG. 7.
[0052]
A punch used in cutting into the electrode plates by the punching includes an upper
20 die and a lower die. The upper die is a movable die 7. The lower die is a fixed die 8. In
the cutting, the movable die 7 moves up and down so that the lead plate 2 passing between the
movable die 7 and the fixed die 8 receives the cutting force of the movable die 7 and the
bearing power of the fixed die 8. Then, the lead plate 2 is cut into the electrode plates 2a.
Specifically, the movable die 7 performs the punching downward at regular time intervals
25 above the lead plate 2 to obtain the electrode plates 2a. At the same time, the protrusions 6
19
are formed at the both ends of the electrode plate by the punching with the movable die 7 in
the cutting.
[0053]
As compared to the rotary cut, the forward speed of the lead plate needs to be
5 synchronized with the punching speed of the upper die in the punching. Thus, the punching
has lower production controllability, is suitable for producing small size electrode plates (e.g.,
ranging from 29 mm to 44.5 mm), and has high production speed.
[0054]
As shown in FIG. 8, the protrusions are usually formed at the both ends at different
10 sides of each electrode plate in the punching. As described above, this formation provides
smaller advantages than the formation of the protrusions at the both ends of the same side of
the electrode plate. Furthermore, as compared to the rotary cut, the punching has the
following disadvantages. Specifically, the punching stress is great, and the cutting force (i.e.,
the punching force) applied to the ends of the electrode plate is particularly great. After the
15 cutting, this causes loose contact between the active material and the grid at the both ends of
the electrode plate to cause fall-off of the active material, thereby reducing the cycle life.
[0055]
Therefore, out of the rotary cut and the punching, the rotary cut is more preferably
performed in the present invention.
20 [0056]
In the present invention, the protrusions formed at the both ends of each electrode
plate are maintained in cutting into the electrode plates by increasing the strength of the active
material at the both ends, that is, increasing the density of the active material. As a result,
the electrode plate still has the larger thickness at the both ends after the cutting. In this
25 respect, the density of the active material layer, that is, the density of the lead paste preferably
20
ranges from 4.15 g/cm3 to 5.0 g/cm3, both inclusive, and more preferably ranges from 4.25
g/cm3 to 4.8 g/cm3, both inclusive. The density of the lead paste within this range is higher
than the density of usual lead paste. The positive electrode plates and the negative electrode
plates use lead paste with different compositions, and different densities of the lead paste are
5 used to form the protrusions. That is, the compositions of the lead paste used for the positive
electrode plates and the negative electrode plates are different, and thus the degree of the
protrusions obtained after the cutting are different even by using the same density of the lead
paste and the same cutting way. In addition, the lead paste for the negative electrode plates
needs to change the composition ratio depending on the actually required characteristics.
10 Thus, even if the densities of the lead paste are equal, different composition ratios provide
different degrees of protrusions. Thus, the electrode plates are preferably positive electrode
plates. The density of the lead paste of the positive electrode plates preferably ranges from
4.15 g/cm3 to 4.45 g/cm3, both inclusive, and more preferably from 4.25 g/cm3 to 4.35 g/cm3,
both inclusive.
15 [0057]
The present invention provides a method of manufacturing each electrode plate
according to the present invention. In the method, rotary cut is performed in the cutting of
the electrode plate. The blade angle of the rotary cut bit used in the rotary cut preferably
ranges from 45° to 75°, both inclusive, and more preferably ranges from 50° to 70°, both
20 inclusive.
[0058]
In the method according to the present invention, the strength of the active material
at the both ends is secured to maintain the protrusions formed at the both ends of each
electrode plate in cutting into the electrode plate. For the purpose, the density of the active
25 material is increased. The density of the active material layer, that is, the density of the lead
21
paste preferably ranges from 4.15 g/cm3 to 5.0g/cm3, both inclusive, and more preferably
ranges from 4.25 g/cm3 to 4.8g/cm3, both inclusive. Thus, the electrode plate is preferably a
positive electrode plate. The density of the lead paste of the positive electrode plate
preferably ranges from 4.15 g/cm3 to 4.45 g/cm3, both inclusive, and more preferably from
5 4.25 g/cm3 to 4.35g/cm3, both inclusive.
[0059]
The present invention further provides an electrode plate group. The electrode
plate group is formed by alternately arranging a plurality of positive electrode plates and a
plurality of negative electrode plates, with a separator interposed between each pair of the
10 positive and negative electrode plates. At least each of the positive electrode plates is the
electrode plate according to the present invention. In particular, in view of increasing the
charge-discharge efficiency and reducing the costs, a negative electrode plate is preferably
provided at the outermost of the electrode plate group. That is, this container includes one
negative electrode plate more than the positive electrode plates. As a result, the active
15 material of the positive electrode plate has a relatively larger space. The chemical reaction
of the positive electrode plates is more active than the chemical reaction of the negative
electrode plates. The volume of the active material largely changes before and after the
reaction. Each positive electrode plate is interposed between the negative electrode plates,
thereby causing uniform discharge at the both ends to reduce the warpage of the positive
20 electrode plates and fall-off of the active material.
[0060]
The present invention further provides a lead storage battery. The lead storage
battery includes the electrode plate group. The lead storage battery according to the present
invention may be a bent lead storage battery or a control valve lead storage battery. The lead
25 storage battery is preferably the control valve lead storage battery.
22
[0061]
The lead storage battery according to the present invention includes the abovedescribed
electrode plate group. Conventionally known configurations and manufacturing
methods are used for the other components, and are not limited.
5 [0062]
For example, the lead storage battery is assembled as follows. Specifically, a
plurality of positive electrode plates and a plurality of negative electrode plates are stacked
with a separator between each pair of the positive and negative electrode plates to obtain an
electrode plate group. Then, in each electrode plate group, positive electrode lugs are
10 welded together by a metal plate made of lead, aluminum, copper, etc., by fusion or casting to
obtain a positive electrode strap. At the same time, in each electrode plate group, negative
electrode lugs are welded together by a metal plate made of lead, aluminum, copper, etc., by
fusion or casting to obtain a negative electrode strap. The battery container is segmented by
partition walls into a plurality of cell chambers, each of which contains one of the electrode
15 plate groups. The negative electrode strap of one of the electrode plate groups is welded to
the positive electrode strap of the electrode plate group of the adjacent cell (i.e., electric cell)
by a metal plate made of lead, aluminum, copper, etc. Then, the negative electrode strap of
the electrode plate group of the adjacent cell is welded to the positive electrode strap of the
electrode plate group of the next adjacent cell by a metal plate made of lead, aluminum,
20 copper, etc. As such, the electrode straps are connected in series, thereby connecting the
electrode plate groups in series, that is, connecting the plurality of cells in series. The last
positive electrode strap and the last negative electrode strap at the both ends serve as a
positive electrode end and a negative electrode end. The positive electrode end is connected
to a positive electrode terminal. The negative electrode end is connected to a negative
25 electrode terminal.
23
[0063]
After that, a battery cover is attached to the opening of the battery container. Then,
after electrolyte is injected from a vent provided in the battery cover to the cells, the
formation is performed in the battery container. Usually, the electrolyte is a sulfuric acid at
5 a concentration ranging from 1.1 to 1.4 g/ml, and may contain additive such as silicon dioxide.
After the formation, a valve for releasing gas and pressure generated inside the battery is fixed
to the vent to obtain a lead storage battery.
[0064]
The present invention will be specifically described hereinafter based on
10 embodiments. These embodiments are however illustrative only and the present invention is
not limited thereto.
[0065]
First Embodiment
(1) Fabrication of Positive Electrode Plate
15 Lead powder (a mixture of lead and lead oxide), water, and a diluted sulfuric acid,
which are materials, were kneaded at a ratio by weight of about 100:12:14 to obtain positive
electrode lead paste as a positive electrode active material.
[0066]
A lead tape, which was obtained by casting and contained a Pb alloy containing Ca
20 of about 0.07 mass% and Sn of about 1.3 mass%, was extruded to have a thickness of 1.3 mm.
First, as shown in FIGS. 4(a) and 4(b), expansion was performed and a lead tape 27 was
repeatedly punched by a reciprocating punch to form a plurality of slits along the length of the
lead tape. At the same time, the slits were expanded in the direction perpendicular to the
surface of the lead tape. As a result, a net sheet with a net 25 including a plurality of crossed
25 wires was formed. Then, the net sheet was shaped by a pair of rollers of a shaping die to
24
obtain an expanded grid. After that, the net 25 in the expanded grid was filled with a lead
paste 24a as an active material along the length of the grid to form a lead plate 2. Then, the
lead plate 2 was cut by the rotary cut into positive electrodes plates, each of which has the lug
9. At this time, a rotary cut bit with a blade angle of 45° was used, and protrusions were
5 formed at the both ends of the same side of each positive electrode plate. The positive
electrode plates cut in this manner were cured, dried, and formed. As a result, the positive
electrode plates were obtained, each of which holds a positive electrode active material layer
in the grid of the positive electrode plate. The formation may be performed before
assembling each electrode plate group, or after assembling and arranging the electrode plate
10 group in a battery container of a lead storage battery.
[0067]
The parameters of the elements of the positive electrode plates are to be referred to
the values indicated in the following Table 1. Out of the parameters, the thickness ratio
H1/H2 of the obtained protrusions was 3% and the width ratio H3/H4 was 15%, and the
15 density of the obtained lead paste was 4.3 g/cm3.
[0068]
(2) Fabrication of Negative Electrode Plate
Lead powder, water, and a diluted sulfuric acid, which are materials, were kneaded
at ratio by weight of about 100:10:4 to obtain negative electrode lead paste as a negative
20 electrode active material. Reciprocating expansion similar to that for the positive electrode
plates was performed using a Pb alloy containing Ca of about 0.07 mass% and Sn of about
0.25 mass% to obtain an expanded grid of each negative electrode plate as a negative
electrode current collector. After being filled with the negative electrode lead paste, the
expanded grid (i.e., the lead plate) was cut by rotary cut into negative electrode plates, each of
25 which has a negative electrode lug. At this time, the blade angle of the used rotary cut bit
25
was 40°. As such, unformed negative electrode plates were obtained. The unformed
negative electrode plates were cured, dried, and formed. As a result, the negative electrode
plates were obtained, each of which holds a negative electrode active material layer in the grid
of the negative electrode plate. The formation may be performed before assembling each
5 electrode plate group, or after assembling and arranging the electrode plate group in the
battery container of the lead storage battery.
[0069]
The parameters of the elements of the positive electrode plates are to be referred to
the values indicated in the following Table 1. Out of the parameters, each of the obtained
10 negative electrode plates has a flat surface and a uniform thickness. No protrusion was
formed at the ends of each negative electrode plate, and thus the thickness ratio H1/H2 of the
ends was 0 and a width ratio H3/H4 was 0. The density of the lead paste of the obtained
negative electrode plates was 4.8 g/cm3.
(3) Fabrication of Lead Storage Battery
15 [0070]
A plurality of positive electrode plates and a plurality of negative electrode plates
were stacked with a separator between each pair of the positive and negative electrode plates
to obtain the electrode plate groups.
[0071]
20 In each electrode plate group obtained in this manner, the positive electrode lugs
having the same polarity were welded to obtain positive electrode straps, and the negative
electrode lugs having the same polarity were welded to obtain negative electrode straps. Six
cell chambers of the battery container separated by partitions contain six electrode plate
groups. The negative electrode strap of one of the electrode plate groups was welded to the
25 positive electrode strap of the adjacent electrode plate group so that the two adjacent electrode
26
plate groups were connected in series. In this manner, the electrode plate groups were
sequentially connected in series. That is, the cells were connected in series.
[0072]
In the plurality of electrode plate groups connected in series, out of two electrode
5 plate groups located at the ends, the positive electrode strap of one of the electrode plate
groups was connected to a positive electrode terminal, and the negative electrode strap of the
other electrode plate group was connected to a negative electrode terminal. After that, the
battery cover was attached to the opening of the battery container. Then, a sulfuric acid at a
concentration of 1.242 g/ml was injected as electrolyte from a vent provided in the battery
10 cover to the cells. At the same time, the formation was performed within the battery
container. After the formation, a valve for releasing gas and pressure generated inside the
battery was fixed to the vent to obtain to obtain the lead storage battery. The capacity of the
battery was 65 Ah and the rated voltage was 12 V.
[0073]
15 (4) Evaluation of Performance of Lead Storage Battery
(A) The cycle life characteristics of the lead storage battery obtained as above
were measured. The obtained result is indicated by the below Table 1.
[0074]
The cycle life was measured as follows.
20 [0075]
After the voltage, the internal resistance, and the weight of a new battery within 30
days from fabrication were measured, the battery was discharged at 16.25 amperes (A) to
reach a discharge end voltage of 10.5 V under the condition of an environmental temperature
25 ± 2 °C. Then, the battery was charged to full charge. The charge was performed under
25 the conditions at a constant voltage of 14.7 V and the maximum charge current of 26A or
27
lower. After the end, this one charging was regarded as a first cycle. Further discharge and
the charge were performed under the conditions and the cycle was repeated. When the
discharge capacity of the battery dropped to 50% of the discharge capacity in the first cycle,
the experiment ended and the number of the performed charge and discharge cycles was
5 obtained. The number of the cycles was regarded as a cycle life.
[0076]
(B) The capacity (i.e., electrolyte reaction effect) of the lead storage battery
obtained as above was measured. The obtained result is indicated by the below Table 1.
[0077]
10 The degree of the electrolyte reaction effect is specifically indicated by the
discharge capacity of the battery. The electrolyte reaction effect is expressed by measuring
the discharge capacity of the battery. The capacity of the battery was measured as follows.
[0078]
After the voltage, the internal resistance, and the weight of a new battery within 30
15 days from fabrication were measured, the battery was discharged at 16.25 amperes (A) to
reach a discharge end voltage of 10.5 V under the condition of an environmental temperature
25 ± 2 °C. Then, the discharge time was recorded (the unit is time represented simply by h),
thereby obtaining the capacity of the battery.
[0079]
20 (C) The charge efficiency (i.e., the charging time) of the lead storage battery
obtained as above was measured. The obtained result is indicated by the below Table 1.
[0080]
The charge efficiency (i.e., the charging time) was measured as follows.
[0081]
25 Constant voltage charge was performed at 25°C at 13.7 V. When the charge
28
current reaches 0.003 or less times of a constant capacity, the battery was determined as being
fully charged and the charge ended. The time from the start of the charge to the end of the
charge was regarded as the charging time (the unit is time represented simply by h). In
general, a battery required a short charging time has great charge efficiency.
5 [0082]
Second to Fourth Embodiments
The blade angle of the rotary cut bit used in cutting into positive electrode plates
was increased to the range from 50° to 60°. The thickness ratio H1/H2 of obtained
protrusions was increased to the range from 4% to 6%. In all the other respects, electrode
10 plate groups and a lead storage battery were fabricated by the same arrangement and the
manufacturing method as the first embodiment.
[0083]
Fifth Embodiment
The punching was used in cutting into positive electrode plates and negative
15 electrode plates. In all the other respects, electrode plate groups and a lead storage battery
were fabricated by the same arrangement and the manufacturing method as the fourth
embodiment.
[0084]
Sixth to Eight Embodiments
20 The blade angle of the rotary cut bit used in cutting into positive electrode plates
was increased to the range from 65° to 75°. The thickness ratio H1/H2 of obtained
protrusions was increased to the range from 7% to 9%. In all the other respects, electrode
plate groups and a lead storage battery were fabricated by the same arrangement and the
manufacturing method as the first embodiment.
25 [0085]
29
First Comparison Example
The blade angle of the used rotary cut bit in cutting into positive electrode plates
and negative electrode plates was reduced to 40°, or punching was performed in cutting into
the positive electrode plates and the negative electrode plates. None of the positive and
5 negative plates has any protrusions. That is, the ratio H1/H2 and the ratio H3/H4 of the
positive and negative electrode plates were all 0. The density of the lead paste of the
positive electrode plates was 4.2 g/cm3. In all the other respects, electrode plate groups and
a lead storage battery were fabricated by the same arrangement and the manufacturing method
as the first embodiment.
10 [0086]
Second Comparison Example
The blade angle of the rotary cut bit used in cutting into positive electrode plates
was reduced to 40°. The thickness ratio H1/H2 of obtained protrusions was reduced to 1%.
In all the other respects, electrode plate groups and a lead storage battery were fabricated by
15 the same arrangement and the manufacturing method as the first embodiment.
[0087]
Third Comparison Example
The blade angle of the rotary cut bit used in cutting into positive electrode plates
was increased to 80°, and the thickness ratio H1/H2 of obtained protrusions was increased to
20 10%. In all the other respects, electrode plate groups and a lead storage battery were
fabricated by the same arrangement and the manufacturing method as the first embodiment.
[0088]
The results of the evaluation of the elements of the electrode plates and the lead
storage batteries obtained in the above-described embodiments and comparison examples arc
25 to be referred to the values indicated by the below table 1 and 2.
30
[0089]
The following is found from the result obtained in the first to fourth embodiments
and the sixth to eighth embodiments. The cycle life, the capacity, and the charge efficiency
of the battery are largely increased by allowing the angle of the blade and the thickness ratio
5 of the protrusions to fall within certain ranges. Specifically, the blade angle ranges from 45°
to 75°, and the ratio H1/H2 ranges from 3% to 9%. Particularly greater advantages can be
obtained by allowing the blade angle to fall within the range from 50° to 70°, and the ratio
H1/H2 to fall within the range from 4% to 8%.
[0090]
10 In the fifth embodiment and the fourth embodiment, the protrusions formed in each
positive electrode plate and each negative electrode plate have the same ratio H1/H2, and the
same ratio H3/H4. Only how to cut is different. The following is found from the result
obtained in the fourth embodiment and the fifth embodiment. The cycle life, the capacity,
and the charge efficiency of the battery can be increased by forming the protrusions by the
15 punching in cutting into the electrode plates, and by allowing the thickness and the width of
the obtained protrusions to fall within certain ranges. However, as compared to the case
where protrusions are formed by rotary cut under equivalent conditions, the advantages
improve less.
[0091]
20 The following is found from the result obtained in the first comparison example.
Where the ratio H1/H2 is 0 and the ratio H3/H4 is 0, no protrusion is formed, thereby causing
no thickness difference between the both ends and the middle portion of each electrode plate.
The cycle life, the capacity, and the charge efficiency of the battery obtained in this case can
be reference values.
25 [0092]
31
In theory, small protrusions are necessarily formed at the end of each electrode plate
in cutting into the electrode plates. Where the density of lead paste is small or where the
blade angle of the rotary cut bit is too small, the strength of the small protrusions decreases.
In a later process to fabricate a finished battery, for example, in stacking the electrode plates,
5 the small protrusions are pressed to be flat upon receipt of pressure and gravity. Therefore,
after the fabrication of the finished battery, both of the ratio H1/H2 and the ratio H3/II4
become 0.
[0093]
The following is found from the result obtained in the second comparison example.
10 Where the ratio H1/H2 is only 1%, the thickness of each protrusion decreases to cause no
great thickness difference between the both ends and the middle portion of the electrode plate.
However, the cycle life, the capacity, and the charge efficiency of the battery increase to some
extent.
[0094]
15 The following is found from the result obtained in the third comparison example.
Where the ratio H1/H2 of the protrusions exceeds 9% and reaches 10%, the thickness HI of
the protrusions is too great, and the pitch between each electrode plate and a separator is loo
great, causing water loss of the electrode plate and losing oxygen gas to cause liquid shortage.
As a result, the cycle life, the capacity, and the charge efficiency of the battery are basically
20 equivalent to those in the first comparison example.
[0095]
Ninth to Fourteenth Embodiments
The blade angle of the rotary cut bit used in cutting into positive electrode plates
was kept to 60°. The thickness ratio H1/H2 of obtained protrusions was kept to 6%. The
25 density of lead paste of the positive electrode plates was changed within the range from 4.15
32
g/cm3to 4.45g/cm3. The width ratio H3/H4 of the obtained protrusions was changed within
the range from 5% to 25%. In all the other respects, electrode plate groups and a lead
storage battery were fabricated by the same arrangement and the manufacturing method as the
first embodiment.
5 [0096]
The following is found from the result obtained in the ninth to fourteenth
embodiments. The density of an active material layer, that is, the density of the lead paste,
of the positive electrode plates, and the width ratio of the obtained protrusions are set to fall
within certain ranges. The cycle life, the capacity, and the charge efficiency of the battery
10 clearly increase.
[0097]
Fifteenth Embodiment
The blade angle of the rotary cut bit used in cutting into positive electrode plates
was 60°. The thickness ratio H1/H2 of obtained protrusions was 6%. The density of lead
15 paste of the positive electrode plates was 4.3g/cm3. The width ratio H3/H4 of obtained
protrusions was 15%. Similarly, with respect to negative electrode plates, the blade angle of
the rotary cut bit used in cutting was 60°, the thickness ratio H1/H2 of obtained protrusions
was 6%, the density of lead paste of the negative electrode plates was 5.0g/cm3, and the width
ratio H3/H4 of the obtained protrusions was 15%. In all the other respects, electrode plate
20 groups and a lead storage battery were fabricated by the same arrangement and the
manufacturing method as the first embodiment.
[0098]
The arrangement of the positive electrode plates in the fifteenth embodiment is
completely the same as those in the fourth embodiment. Only the arrangement of the
25 negative electrode plates is different. The fifteenth embodiment is compared to the result
J J
obtained in the fourth embodiment. The proper protrusions are formed in both of the
positive electrode plates and the negative electrode plates, thereby further increasing the cycle
life, the capacity, and the charge efficiency of the battery as compared to the case where the
protrusions are formed in the positive electrode plates or the negative electrode plates only.
5 [0099]
Sixteenth Embodiment
Punching was employed to cut into positive electrode plates. The thickness ratio
H1/H2 of protrusions formed at the both ends of each positive electrode plate was 2.5%.
The density of lead paste of the positive electrode plates was 4.3 g/cm3. The width ratio
10 H3/H4 of the obtained protrusions was 5%. Although the punching was also used for the
negative electrode plates, no protrusion was formed. In all the other respects, electrode plate
groups and a lead storage battery were fabricated by the same arrangement and the
manufacturing method as the first embodiment.
[0100]
15 The following is found from the result obtained in the sixteenth embodiment. The
cycle life, the capacity, and the charge efficiency of the battery can be increased by forming
protrusions by punching in the cutting into the electrode plates, and setting the thickness and
the width of the obtained protrusions to fall within certain ranges.
[0101]
20 As described above, the present invention effectively fabricates a lead storage
battery having a long cycle life, large capacity, and great charge efficiency at low costs by
simply adjusting the manufacturing process.
25
34
[0102]
TABLE 1
EMBODIMENT 1
EMBODIMENT 2
EMBODIMENT 3
EMBODIMENT 4
EMBODIMENT 5
EMBODIMENT 6
EMBODIMENT 7
EMBODIMENT 8
POSITIVE ELECTRODE PLATE
GRID
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
CUTTING
TYPE
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
PUNCHIN
G
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
BLADE
ANGLE
O
45
50
55
60
NONE
65
70
75
HI/
H2
3%
4%
5%
6%
6%
7%
8%
9%
LEAD
PASTE
DENSITY
(g/cm3)
4.3
4.3
4.3
4.3
4.3
4.3
4.3
4.3
H3/
H4
15%
15%
15%
15%
15%
15%
15%
15%
NEGATIVE ELECTRODE PLATE
CUTTING
TYPE
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
PUNCHING
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
BLADE
ANGLE
(°)
40
40
40
40
NONE
40
40
40
GRID
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
H1/H2
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
LEAD
PASTE
DENSITY
(g/cm')
4.8
4.8
4.8
4.8
4.8
4.8
4.8
4.8
H3/
H4
0
0
0
0
0
0
0
0
EVALUATION RESULT
CYCLE
LIFE
250
TIMES
350
TIMES
400
TIMES
450
TIMES
350
TIMES
400
TIMES
350
TIMES
250
TIMES
BATTERY
CAPACITY
65 Ah
68.3 Ah
69.9 Ah
71.5 Ah
68.3 Ah
69.9 Ah
68.3 Ah
65 Ah
CHARGE
EFFICIENCY
(CHARGE
HOUR)
20 h
18 h
16 h
14 h
18 h
16 h
18 h
20 h
35
[0103]
TABLE 2
COMPARISON
EXAMPLE 1
COMPARISON
EXAMPLE 2
COMPARISON
EXAMPLE 3
EMBODIMENT 9
EMBODIMENT 10
EMBODIMENT 11
EMBODIMENT 12
EMBODIMENT 13
EMBODIMENT 14
EMBODIMENT 15
EMBODIMENT 16
POSITIVE ELECTRODE PLATE
GRID
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
CUTTING
TYPE
ROTARY CUT/
PUNCHING
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
ROTARY CUT
PUNCHING
BLADE
ANGLE
(°)
40/
NONE
40
80
60
60
60
60
60
60
60
NONE
HI/
H2
0
1%
10
%
6%
6%
6%
6%
6%
6%
6%
2.5
%
LEAD
PASTE
DENSITY
(g/cm')
4.2
4.3
4.3
4.15
4.2
4.25
4.35
4.4
4.45
4.3
4.3
H3/H4
0
15%
15%
5%
10%o
13%
17%
20%
25%
15%
5%
NEGATIVE ELECTRODE PLATE
CUTTING
TYPE
ROTARY
CUT/
PUNCHING
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
ROTARY
CUT
PUNCHING
BLADE
ANGLE
O
40/
NONE
40
40
40
40
40
40
40
40
60
NONE
GRID
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
EXPANSION
H1/H2
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
0
(FLAT)
6%
0
(FLAT)
LEAD
PASTE
DENSIT
Y
(g/cm')
4.8
4.8
4.8
4.8
4.8
4.8
4.8
4.8
4.8
5.0
4.8
H3/
H4
0
0
0
0
0
0
0
0
0
15
%
0
EVALUATION RESULT
CYCLE
LIFE
100
TIMES
200
TIMES
100
TIMES
300
TIMES
350
TIMES
400
TIMES
400
TIMES
350
TIMES
300
TIMES
500
TIMES
300
TIMES
BATTERY
CAPACITY
59.6 Ah
63.4 Ah
59.6 Ah
66.6 Ah
68.3 Ah
69.9 Ah
69.9 Ah
68.3 Ah
66.6 Ah
73.1 Ah
66.6 Ah
CHARGE
EFFICIENCY
(CHARGE
HOUR)
30 h
24 h
30 h
20 h
18 h
16 h
16 h
18 h
20 h
12 h
20 h
INDUSTRIAL APPLICABILITY
The present invention provides a battery electrode plate, which is simply
processible at low costs and having large capacity, a longer cycle life, and great charge
5 efficiency, and a lead storage battery including the electrode plate. The battery is applicable
to power supplies of electric vehicles, electric bicycles, electric motorcycles, electric scooters,
two-wheel small motorcycles, etc.
37
CLAIMS
1. A battery electrode plate comprising:
a current collector; and
an active material layer supported by the current collector, wherein
the current collector is an expanded grid fabricated by expansion,
the battery electrode plate includes
two protruding ends, each having a protrusion, and
a flat middle portion located between the two ends,
the ends have a greater thickness than the middle portion, and
where the thickness at the middle portion is H2, and a difference between the
thickness at the ends and the thickness at the middle portion is HI, a ratio of HI to H2
(H1/H2) ranges from 3% to 9%.
2. The battery electrode plate of claim 1, wherein
the ratio H1/H2 ranges from 4% to 8%.
3. The battery electrode plate of claim 1, wherein
a width of the ends ranges from 5% to 25% of a width of the entire battery electrode
plate.
4. The battery electrode plate of claim 3, wherein
the width of the ends ranges from 10% to 20% of the width of the entire battery
electrode plate.
5. The battery electrode plate of claim 1, wherein
the protrusions of the two protruding ends are formed at a same side of the battery
electrode plate.
6. The battery electrode plate of claim 1, wherein
the protrusions of the two protruding ends are formed at different sides of the
battery electrode plate.
7. The battery electrode plate of claim 1, wherein
the protrusions are formed by rotary cut in cutting into the battery electrode plate.
8. The battery electrode plate of claim 7, wherein
a rotary cut bit used in the rotary cut has a blade angle ranging from 45° to 75°.
9. The battery electrode plate of claim 8, wherein
the rotary cut bit used in the rotary cut has the blade angle ranging from 50° to 70°.
10. The battery electrode plate of claim 1, wherein
the protrusions are formed by punching in cutting into the battery electrode plate.
11. The battery electrode plate of claim 1, wherein
the active material layer of the battery electrode plate has a density ranging from
4.15 g/cm3to5.0g/cm3.
12. The battery electrode plate of claim 1, wherein
the battery electrode plate is a positive electrode plate.
13. The battery electrode plate of claim 12, wherein
the active material layer of the positive electrode plate has a density ranging from
4.15 g/cm3 to 4.45 g/cm3.
14. A method of manufacturing the battery electrode plate of any one of
claims 1-6, comprising:
performing rotary cut in cutting into the battery electrode plate, wherein
a rotary cut bit used in the rotary cut has a blade angle ranging from 45° to 75°.
15. The method of claim 14, wherein
the blade angle ranges from 50° to 70°.
16. The method of claim 14, wherein
a density of the active material layer, which is a density of lead paste, of the battery
electrode plate ranges from 4.15 g/cm3 to 5.0 g/cm3.
17. The method of claim 14, wherein
the battery electrode plate is a positive electrode plate.
18. The method of claim 17, wherein
a density of the active material layer, which is a density of lead paste, of the positive
electrode plate ranges from 4.15 g/cm3 to 4.45 g/cm3.
19. An electrode plate group comprising:
a plurality of positive electrode plates and a plurality of negative electrode plates
alternately arranged with a separators interposed between each pair of the positive and
negative electrodes, and
at least each of the positive electrode plates is the battery electrode plate of any one
of claims 1-11.
20. A lead storage battery comprising:
the electrode plate group of claim 19.