Title: Negative active material, method of manufacturing its material, and lead acid battery
Abstract: A negative active material is characterized by being prepared by adding a lignin having a unit structure represented by the formula (I) as the main structure to a lead oxide. Since the lignin of the formula (I) is added, the negative active material can be prevented from shrinkage due to charge/discharge. ##STR1##
(wherein R1 is H, OH, COOH, SO3H, SH, C6H5, COO-, SO3-, R2C6H4, (R2)2C6H3, or (R2)3C6H2; and R2 is at least one member selected from among OH, COOR, SO3H, and CH2SO3H.)
Patent Number: 7,022,433 Issued on 04/04/2006 to Umetani, et al.
| Inventors:
|
Umetani; Hirofumi (Takatsuki, JP);
Ban; Ikumi (Takatsuki, JP);
Eguchi; Yoshihiro (Takatsuki, JP)
|
| Assignee:
|
GS Yuasa Corporation (Kyoto, JP)
|
| Appl. No.:
|
381282 |
| Filed:
|
November 8, 2001 |
| PCT Filed:
|
November 8, 2001
|
| PCT NO:
|
PCT/JP01/09758
|
| 371 Date:
|
March 24, 2003
|
| 102(e) Date:
|
March 24, 2003
|
| PCT PUB.NO.:
|
WO02/39519 |
| PCT PUB. Date:
|
May 16, 2002 |
| Current U.S. Class: |
429/212; 29/623.1 |
| Current Intern'l Class: |
H01M 4/60 (20060101); H01M 6/00 (20060101) |
References Cited [Referenced By]
| Foreign Patent Documents |
| 7147160 | Jun., 1995 | JP.
| |
| 9007630 | Jan., 1997 | JP.
| |
| 9147872 | Jun., 1997 | JP.
| |
| 11121008 | Apr., 1999 | JP.
| |
| 11204111 | Jul., 1999 | JP.
| |
| 2001202987 | Jul., 2001 | JP.
| |
Primary Examiner: Barr; Michael
Assistant Examiner: Hodge; Robert
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
What is claimed is:
1. A negative active material, comprising:
a lead oxide, and
a lignin having a unit structure represented by the formula (I) as the main structure.
##STR12##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
2. A negative active material, comprising:
a lead oxide, and
a lignin having a unit structure represented by the formula (II) as the main
structure.
##STR13##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
3. A negative active material as set forth in 2, in which an amount of the lignin
ranges from 0.2 to 0.6 mass % relative to the lead oxide.
4. A method of manufacturing a negative active material, comprising the step
of adding at least a lignin having a unit structure represented by the formula
(I) as the main structure to a lead oxide.
##STR14##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
5. A method of manufacturing a negative active material, comprising the step
of adding at least a lignin having a unit structure represented by the formula
(II) as the main structure to a lead oxide.
##STR15##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
6. A method of manufacturing a negative active material as set forth in 5, in
which an adding amount of the lignin ranges from 0.2 to 0.6 mass % relative to
the lead oxide.
7. A lead acid battery having a positive electrode and a negative electrode,
in which a negative active material composing the negative electrode is comprised
of a lead oxide and a lignin having a unit structure represented by the formula
(I) as the main structure.
##STR16##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
8. A lead acid battery having a positive electrode and a negative electrode,
in which a negative active material composing the negative electrode is comprised
of a lead oxide and a lignin having a unit structure represented by the formula
(II) as the main structure.
##STR17##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
9. A lead acid battery as set forth in 8,
in which a positive electrode grid composing the positive electrode made of a
lead alloy which does not contain an antimony.
10. A lead acid battery as set forth in claim 9,
in which the positive active material composing the positive electrode is comprised
of a lead oxide and an antimony compound, the antimony compound is Sb
2SO
3,
Sb
2SO
5 or a mixture of them, and its amount ranges from 0.05
to 0.2 mass % relative to the lead oxide.
11. A lead acid battery as set forth in 8,
in which an amount of the lignin ranges from 0.2 to 0.6 mass % relative to the
lead oxide.
Description
TECHNICAL FIELD
This invention relates to a negative active material, a method of manufacturing
its material and a lead acid battery.
BACKGROUND OF THE INVENTION
A lead acid battery is being widely used for a power source for starting an automobile
engine and a power source for supplying electric power to various electrical equipments.
The lead acid battery includes such a problem that a high-rate discharge performance
of a negative electrode is deteriorated earlier than that of a positive electrode
when charge/discharge operations are repeated, so that a battery life is limited
due to the negative electrode. The cause is supposed to be attributable to a fact
that a negative active material shrinks due to charge/discharge to cause a decrease
in a surface area of the negative active material. In order to dissolve the above
problem, a negative active material becomes used which is prepared by adding a
lignin having a unit structure represented by the formula (III) to a lead oxide.
##STR2##
In this instance, the lignin is a component included in a wood, and is a by-product
produced when manufacturing pulp in a paper making factory. Since there are many
processes for manufacturing pulp, it can be said that there are so many kinds of
the lignin corresponding to those processes. The lignin of the formula (III) is
called lignosulfonate which is produced by a method of sulfite digesting. Since
sulfurous acid is used in this method, sulfonic acid group is introduced into α-position
of the side chain in the structure. The lignin of the formula (III) has a merit
of large water-solubility, but has a demerit that it can not be modified easily.
On the other hand, a Pb—Sb alloy has conventionally been used for a positive
electrode grid in the lead acid battery. However, a type of the lead acid battery
using the Pb—Sb alloy includes such a problem that antimony in the alloy
causes a lowering of a hydrogen over-voltage of the negative electrode, so that
its maintenance becomes troublesome because a periodic supplement of water becomes
required due to an increase of the electrolyte's decrease. For this reason, a hybrid
type lead acid battery using the Pb—Sb alloy which has an antimony content
half as much as a conventional battery, has been put in use. However, a calcium
type lead acid battery using a Pb—Ca alloy is getting a large share in the
market of the lead acid battery.
SUMMARY OF THE INVENTION
In the negative active material produced by adding the lignin of the formula
(III)
to the lead oxide, there has been such a problem that an effect by the lignin,
i.e. an effect to dissolve an earlier deterioration of the high-rate discharge
performance of the negative electrode, is weakened due to a gradual deterioration
of the lignin. The lignin has been deteriorated remarkably because a temperature
surrounding the battery arises up to about 70° C. in a summer season, particularly
when the lead acid battery is put in a engine compartment of automobile.
While, in the calcium type lead acid battery, there is such a problem as an
early decrease in a capacity of the positive electrode, because of producing a
passive state on a surface between the positive electrode grid and the positive
active material due to over-discharge standing and because of forming a PbSO
4
layer on a surface of the positive electrode grid due to repeating deep discharges.
The hybrid type lead acid battery has included such a problem that the electrolyte's
decrease becomes large to accelerate a battery deterioration particularly under
a high-temperature environment, as compared with that of the calcium type lead
acid battery. As a technology to dissolve such problems, the positive active material
produced by adding antimony compound to the lead oxide is disclosed in the JP 7-147160
A. According to this technology, the cycle life performance of the positive electrode
can be improved by adding the antimony compound of proper quantity. However, since
an object of the above-mentioned technology is to improve the cycle life performance
of the positive electrode, this is not effective for the lead acid battery in which
the cycle life performance of the negative electrode is inferior to the cycle life
performance of the positive electrode.
A first object of this application is to provide a negative active material which
can improve a cycle life performance of a negative electrode.
A second object of this application is to provide a method of manufacturing a
negative
active material which can improve a cycle life performance of a negative electrode.
A third object of this application is to provide a lead acid battery which can
improve a cycle life performance of the battery by improving cycle life performances
of both a positive electrode and a negative electrode.
In order to accomplish the first object, the first invention of this application
comprises a negative active material characterized by being prepared by adding
a lignin having a unit structure represented by the formula (I) as the main structure
to a lead oxide.
##STR3##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
According to the first invention, the negative active material can be prevented
from shrinkage due to charge/discharge because the lignin of the formula (I) is
added to it. Since the lignin of the formula (I) is hard to be deteriorated even
under a high-temperature environment, the effect to prevent the negative active
material from shrinkage can be kept for a long period even under the high-temperature
environment. Therefore, according to this invention, the worsening of a high-rate
discharge performance of the negative electrode can be controlled for a long period
even under the high-temperature environment. Consequently, the life performance
of the negative electrode can be improved.
The lignin of the formula (I) is one in which a sulfonic acid group is introduced
through methyl into an aromatic nucleus, and called sulfo-methylated lignin. This
lignin can be obtained by introducing a sulfomethyl group into the aromatic nucleus
of a kraft lignin. Sulfo-methylation is easily done by a treatment at high temperature
using sodium sulfite and formaldehyde. The kraft lignin has a small molecular weight
and a characteristic of being easily modified. The sulfo-methylation is only an
example of modification. The kraft lignin is obtained by a kraft digesting. In
the kraft digesting, sodium hydroxide and sodium sulfide are used and the sulfonic
acid group is not introduced into the structure of the lignin. The kraft lignin
is hard to be dissolved in water. However, the sulfo-methylated lignin has a characteristic
of being easily dissolved in water.
The lignin of the formula (I) is most generally used as sodium salt, but may
be used as potassium salt or other salts.
The reason why the lignin of the formula (I) is assigned as the main structure
is that such a structure, in which one CH
2SO
3-
exists in plural such fundamental structures connected each other, may be thought of.
In order to accomplish the first object, the second invention of this application
comprises a negative active material characterized by being prepared by adding
a lignin having a unit structure represented by the formula (II) as the main structure
to a lead oxide.
##STR4##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
According to the second invention, the life performance of the negative
electrode can be improved by virtue of its containing the lignin of the formula
(II), in the same reason as the first invention.
The lignin of the formula (II) is one in which the sulfonic acid group is directly
introduced into the aromatic nucleus. This lignin can be obtained by treating the
kraft lignin using sodium hydroxide, sodium sulfite and potassium ferricyanide.
The reason why the lignin of the formula (I) is assigned as the main structure
is that such a structure, in which one SO
3- exists in plural
such fundamental structures connected each other, may be thought of.
It is preferable that the first and second inventions contain the following concept (A).
(A) An adding amount of the lignin ranges from 0.2 to 0.6 mass % relative to
the lead oxide.
According to the concept (A), the life performance of the negative electrode
can be improved effectively.
In order to accomplish the second object, the third invention of this application
comprises a method of manufacturing a negative active material characterized by
being provided with a process in which at least a lignin having a unit structure
represented by the formula (I) as the main structure is added to a lead oxide.
##STR5##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
According to the third invention, the negative active material of the first
invention can be obtained.
In order to accomplish the second object, the fourth invention of this application
comprises a method of manufacturing a negative active material characterized by
being provided with a process in which at least a lignin having a unit structure
represented by the formula (II) as the main structure is added to a lead oxide.
##STR6##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
According to the fourth invention, the negative active material of the
second invention can be obtained.
It is preferable that the third and fourth inventions contain the following concept (B).
(B) An adding amount of the lignin ranges from 0.2 to 0.6 mass % relative to
the lead oxide.
According to the concept (B), the negative active material improved effectively
in its life performance can be obtained.
In order to accomplish the third object, the fifth invention of this application
comprises a lead acid battery having positive electrodes and negative electrodes,
in which a negative active material composing the negative electrode is characterized
by being prepared by adding a lignin having a unit structure represented by the
formula (I) as the main structure to a lead oxide.
##STR7##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
According to the fifth invention, the life performance of the negative
electrode can be improved because the lignin of the formula (I) is added to the
negative active material. Therefore, according to this invention, the life performance
of the battery can be prevented from being limited by the negative electrode. For
this reason, the life performance of the battery can be improved by using the positive
electrode having a long life.
In order to accomplish the third object, the sixth invention of this application
comprises a lead acid battery having positive electrodes and negative electrodes,
in which a negative active material composing the negative electrode is characterized
by being prepared by adding a lignin having a unit structure represented by the
formula (II) as the main structure to a lead oxide.
##STR8##
(wherein R
1 is H, OH, COOH, SO
3H, SH, C
6H
5,
COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2;
and R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3H.)
Even in the sixth invention, the life performance of the battery can be prevented
from being limited by the negative electrode because the lignin of the formula
(II) is added, in the same reason as the fifth invention.
It is preferable that the following concepts (C) & (D) are used in the fifth
and
sixth inventions.
(C) The positive electrode grid composing the positive electrode is comprised
of a lead alloy which does not contain antimony.
According to the concept (C), electrolyte's decrease can be controlled
further because the positive electrode grid is comprised of the lead alloy which
does not contain the antimony. Therefore, troublesome maintenances such as supplying
water etc. can be reduced.
Further, in the concept (C), it is preferable that the following concept
(a) is used.
(a) The positive active material composing the positive electrode is prepared
by adding antimony compound to a lead oxide, the added antimony compound is Sb
2O
3,
Sb
2O
5, or a mixture of them, and an adding amount of the
antimony compound ranges from 0.05 to 0.2 mass % relative to the lead oxide.
According to the concept (a), the formation of PbSO
4 layer on
the surface between the positive electrode grid and the positive active material
is controlled, because the positive electrode grid is comprised of the lead alloy
which does not contain the antimony and the antimony compound is added to the positive
active material, so that the life performance of the positive electrode can be
improved. Consequently, the life performance of the battery can be improved further
by combining with the improvement of the life performance of the negative electrode.
(D) An adding amount of the lignin ranges from 0.2 to 0.6 mass % relative to
the lead oxide.
According to the concept (D), effects of the third and fourth inventions
can be obtained effectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
EXAMPLE 1
A lead acid battery was produced as follows.
Production of Negative Electrode
Manufacture of Negative Active Material
A lead oxide, a lignin, barium sulfate and an active material reinforcing agent
were stirred and mixed to prepare a negative active material. An adding amount
of the lignin was 0.2 mass % relative to the lead oxide, an adding amount of the
barium sulfate was 1.2 mass % relative to the lead oxide, and an adding amount
of the active material reinforcing agent was 0.03 mass % relative to the lead oxide.
The active material reinforcing agent is a short fiber comprising polypropylene
resin. The lignin is one having a unit structure represented by the formula (I)
wherein R
1 is OH. The lignin of the formula (I) is used as sodium salt.
Further, the lignin of the formula (I) is prepared by sulfomethylating a kraft lignin.
##STR9##
Production of Negative Electrode
Dilute sulfuric acid and water were kneaded together in the negative active
material to prepare an active material paste. Then, the active material paste was
filled in an expanded grid made of Pb—Ca—Sn alloy, cured and dried.
Thereby, unformed negative electrodes were produced.
Production of Positive Electrode
Dilute sulfuric acid and water were kneaded together in a lead oxide to prepare
an active material paste. Then, the active material paste was filled in an expanded
grid made of Pb—Sb alloy, cured and dried. Thereby, unformed positive electrodes
were produced.
Production of Lead Acid Battery
The positive electrode, the negative electrode and a separator made of polyethylene
between them, were stacked to prepare an assembled element. This assembled element
was inserted in a container made of polypropylene. Electrolyte comprised mainly
of dilute sulfuric acid having a specific gravity of 1.28 (20° C.) was poured
into the container so as to carry out case formation. Thus, a lead acid battery
was produced.
EXAMPLES 2 to 4
Lead acid batteries were produced with the same procedures as those of Example
1, except that the adding amount of the lignin was varied as 0.4 mass %, 0.6 mass
%, and 0.8 mass %. These batteries were named as Examples 2 to 4, in this order.
COMPARATIVE EXAMPLE 1
A lead acid battery was produced with the same procedures as those of Example
1,
except that a lignin having a unit structure represented by the formula (III) was
used and its adding amount was varied as 0.2 mass %. The lignin of the formula
(III) was used as sodium salt. The reason why the adding amount of 0.2 mass % was
selected was that the effect due to the lignin of the formula (III) was best result.
##STR10##
The lead acid batteries of Examples 1 to 4 and Comparative example 1 had a nominal
specifications of 8 Ah (10 HR) and 12V.
Test 1
The lead acid batteries of Examples 1 to 4 and Comparative example 1 were subjected
to cycle life tests under the following test conditions.
Test Conditions
Charge/discharge operations were repeated under such conditions
as an ambient temperature of 75° C., a discharge current of 4.17A, a discharge
time of 4 min., a charge current of 2.47A and a charge time of 10 min. Then, capacity
tests were done every 480 cycles.
Capacity Test
The discharge operation was done at an ambient temperature of -18 ° C. with
a current of 80 A, and a discharge capacity to reach a battery voltage of 6.0V
was measured.
Result
Discharge capacities at 2,400 cycles and 4,800 cycles are listed in Table
1. In these batteries, a discharge capacity of Comparative example 1 is assumed
as 100%.
| |
TABLE 1 |
| |
|
| |
Negative |
Life performance |
| |
active material |
2400 cycle: |
4500 cycle: |
| |
Lignin |
Adding |
Discharge |
Discharge |
| |
(Chemical |
amount |
capacity |
capacity |
| Battery |
formula) |
(Mass %) |
(%) |
(%) |
|
| Example 1 |
formula (I) |
0.2 |
104 |
108 |
| Example 2 |
formula (I) |
0.4 |
109 |
112 |
| Example 3 |
formula (I) |
0.6 |
105 |
107 |
| Example 4 |
formula (I) |
0.8 |
104 |
102 |
| Comparative |
formula (III) |
0.2 |
100 |
100 |
| example 1 |
|
Consideration
The cycle life performances of the lead acid batteries of Example 1 to 4 were
superior to that of the lead acid battery of Comparative example 1.
The lead acid batteries of Example 1 to 4 and Comparative example 1 were disassembled
and examined after completion of 4,800 cycles, and the following facts became clear.
(1) In the lead acid battery of Comparative example 1, shrinkage of the negative
active material proceeded.
(2) In the lead acid batteries of Example 1 to 4, deterioration of the negative
electrodes as in case of Comparative example 1 was scarcely recognized. It can
be thought that this is owing to the effect of the lignin.
(3) In the lead acid battery of Example 4, the accumulation of the lead sulfate
due to the lack of the charge for the negative electrodes was recognized.
As seen from Examples 1 to 4 and Comparative example 1, the life performance
of
the lead acid battery can be improved when the negative active material is used,
which is prepared by adding the lignin having the unit structure of the formula
(I) to the lead oxide. It is preferable that the adding amount of the lignin ranges
from 0.2 to 0.6 mass %.
EXAMPLE 5
A lead acid battery was produced with the same procedures as those of Example
1,
only except for the following points.
(i) A material of the positive electrode grid made of Pb—Ca—Sn alloy
was used.
(ii) A material having a unit structure represented by the formula (II) was
used as the lignin in the negative active material. R
1 in the formula
is OH. The lignin of the formula (II) was used as sodium salt. The adding amount
was 0.2 mass % same as the case of Example 1.
##STR11##
EXAMPLES 6 & 7
Lead acid batteries were produced with the same procedures as those of Example
5, except that the adding amount of the lignin was varied as 0.4 mass % and 0.6
mass % respectively. These batteries were named as Example 6 & 7, in this order.
COMPARATIVE EXAMPLE 2
A lead acid battery was produced with the same procedures as those of Example
5,
except that a lignin having a unit structure represented by the formula (III) was
used and its adding amount was varied as 0.2 mass %.
The lead acid batteries of Examples 5 to 7 and Comparative example 2 had a nominal
capacity of 27Ah and positive electrode dimensions of a longitudinal length; 115
mm, a lateral length: 103 mm, and a thickness: 1.5 mm.
Test 2
The lead acid batteries of Examples 5 to 7 and Comparative example 2 were subjected
to the cycle life tests under the following test conditions.
Test Conditions
Charge/discharge operations were done under such conditions as an
ambient temperatures of 25° C. and 75° C., a discharge current of 25A,
a discharge time of 4 min., a charge current of 25A, and a charge time of 10 min.
Thereafter, a judgement discharge was done with a current of 272 A, so that the
battery life was judged to be ended when a voltage after 30 seconds becomes below 7.2V.
Results are listed in Table 2. A cycle life number of the lead acid battery
of Comparative example 2 at 75° C. is assumed as 100%.
| |
TABLE 2 |
| |
|
| |
Negative |
Life performance |
| |
active material |
25° C.: |
75° C.: |
| |
Lignin |
Adding |
Cycle life |
Cycle life |
| |
(Chemical |
amount |
number |
number |
| Battery |
formula) |
(Mass %) |
(%) |
(%) |
|
| Example 5 |
formula (II) |
0.2 |
128 |
121 |
| Example 6 |
formula (II) |
0.4 |
145 |
142 |
| Example 7 |
formula (II) |
0.6 |
132 |
128 |
| Comparative |
formula (III) |
0.2 |
110 |
100 |
| example 2 |
|
Consideration
The cycle life performances of the lead acid batteries of Examples 5 to 7 were
superior to those of the lead acid battery of Comparative example 2 even at an
ordinary temperature of 25° C. and a high temperature of 75° C. Particularly,
at the high temperature of 75° C., the life performances of the lead acid
batteries of Examples 5 to 7 were superior to those of the lead acid battery of
Comparative example 2 by about 21% to 42%.
The lead acid batteries of Examples 5 to 7 and Comparative example 2 were disassembled
and examined after completion of the cycle life test at 75° C., and the following
facts became clear.
(1) In the lead acid battery of Comparative example 2, the negative active material
shrunk and the accumulation of the lead sulfate, i.e. so called as "sulfation",
proceeded to cause a limitation of the battery life by the negative electrode.
(2) In the lead acid batteries of Examples 5 to 7, the battery life was expired
by the deterioration of the positive electrodes and the deterioration of negative
electrodes as occurred in Comparative example 2 was not recognized. It can be thought
that this is owing to the effect of the lignin.
(3) In the lead acid batteries of Examples 5 to 7, the electrolyte's decrease
of them was small as compared with the lead acid batteries of Examples 1 to 4.
As seen from Examples 5 to 7 and Comparative example 2, the life performance
of
the lead acid battery can be improved when the negative active material is used,
which is prepared by adding the lignin having the unit structure represented by
the formula (II) to the lead oxide. Particularly, the life performances at high
temperature are excellent. It is preferable that the adding amount of the lignin
ranges from 0.2 to 0.6 mass %. Since the positive electrode grid was made of the
lead alloy which does not contain the antimony, the electrolyte's decrease can
be controlled.
EXAMPLE 8
A lead acid battery was produced with the same procedures as those of Example
5,
only except for the following points.
A lignin in which R
1 in the formula (II) is SH is used, and the adding
amount was varied as 0.1 mass %.
EXAMLES 9 to 12
Lead acid batteries were produced with the same procedures as those of Example
8, except that the adding amount of the lignin was varied as 0.2 mass %, 0.4 mass
%, 0.6 mass % and 0.8 mass %, respectively. These batteries were named as Examples
9 to 12, in this order.
The lead acid batteries of Examples 8 to 12 had a nominal capacity of 27 Ah,
and positive electrode dimensions of a longitudinal length: 115 mm, a lateral length:
103 mm, and a thickness: 1.5 mm.
Test 3
The lead acid batteries of Examples 8 to 12 were subjected to the cycle life
tests same as that of the test 2.
Results are listed in Table 3. A cycle life number of the lead acid battery
of Comparative example 2 at 75° C. was assumed as 100%.
| |
TABLE 3 |
| |
|
| |
Negative |
Life performance |
| |
active material |
25° C.: |
75° C.: |
| |
Lignin |
Adding |
Cycle life |
Cycle life |
| |
(Chemical |
amount |
number |
number |
| Battery |
formula) |
(Mass %) |
(%) |
(%) |
|
| Example 8 |
formula (II) |
0.1 |
109 |
110 |
| Example 9 |
formula (II) |
0.2 |
143 |
152 |
| Example 10 |
formula (II) |
0.4 |
145 |
160 |
| Example 11 |
formula (II) |
0.6 |
128 |
148 |
| Example 12 |
formula (II) |
0.8 |
118 |
125 |
|
Consideration
The cycle life performances of the lead acid batteries of Examples 8 to 12 were
superior to those of the lead acid battery of Comparative example 2 even at an
ordinary temperature of 25° C. and a high temperature of 75° C. Particularly,
at the high temperature of 75° C., the life performances of the lead acid
batteries of Examples 8 to 12 were superior to those of the lead acid battery of
Comparative example 2 by about 10% to 60%.
The lead acid batteries of Examples 8 to 12 were disassembled and examined after
completion of the cycle life test at 75° C., and the following facts became clear.
(1) In the lead acid batteries of Examples 8 to 12, the battery life was expired
by the deterioration of the positive electrodes and the deterioration of the negative
electrodes as occurred in Comparative example 2 was not recognized. It can be thought
that this is owing to the effect of the lignin.
(2) In the lead acid batteries of Examples 8 to 12, the electrolyte's decrease
of them was small as compared with the lead acid batteries of Examples 1 to 4.
As seen from Examples 8 to 12 and Comparative example 2, the life performance
of the lead acid battery can be improved when the negative active material is used,
which is prepared by adding the lignin having the unit structure represented by
the formula (II) to the lead oxide. Particularly, the life performances at high
temperature are excellent. The life performance at high temperature can be improved
further in the lead acid battery using the lignin in which R
1 in the
formula (II) is SH, as compared with the lead acid battery using the lignin in
which R
1 is OH. Since the positive electrode grid was made of the lead
alloy which does not contain the antimony, the electrolyte's decrease can be controlled.
In order to examine an optimum adding amount of an antimony compound when adding
the antimony compound to the positive active material, lead acid batteries of Comparative
examples 3 to 9 were produced.
COMPARATIVE EXAMPLE 3
A lead acid battery was produced as follows.
Production of Negative Electrode
Dilute sulfuric acid and water were kneaded together in a lead oxide to prepare
an active material paste. Then, the active material paste was filled in an expanded
grid made of Pb—Ca—Sn alloy, cured and dried. Thereby, unformed negative
electrodes were obtained.
Production of Positive Electrode
A lead oxide and Sb
2O
3 were stirred and mixed together
to
prepare an active material. An adding amount of the Sb
2O
3 relative
to the lead oxide was 0.05 mass %. Then, the active material, dilute sulfuric acid
and water were kneaded together to prepare an active material paste. Thereafter,
the active material paste was filled in an expanded grid made of Pb—Ca—Sn
alloy, cured and dried. Thereby, unformed positive electrodes were produced.
Production of Lead Acid Battery
A lead acid battery was produced in the same as Example 1.
COMPARATIVE EXAMPLES 4 to 8
Lead acid batteries were produced with the same procedures as those of Comparative
example 3, except that the adding amount of the Sb
2O
3 was
varied as 0.1 mass %, 0.2 mass %, 0.3 mass %, 0.4 mass %, and 0.5 mass %, respectively.
These batteries were named as Comparative examples 4 to 8, in this order.
COMPARATIVE EXAMPLE 9
A lead acid battery was produced with the same procedures as those of Comparative
example 3, except that the Sb
2O
3 was not added. The lead
acid batteries of Comparative examples 3 to 9 had a nominal capacity of 27 Ah,
and positive electrode dimensions of a longitudinal length: 115 mm, a lateral length:
103 mm, and a thickness: 1.5 mm.
Test 4
The lead acid batteries of Comparative examples 3 to 9 were subjected to the
cycle life tests under the following test conditions.
Test Conditions
Charge/discharge operations were done under such conditions as an
ambient temperatures of 75° C., a discharge current of 25 A, a discharge time
of 4 min., a charge current of 25 A, and a charge time of 10 min. Then, discharge
was done for more than 56 hours on every 480 cycles. Thereafter, a judgement discharge
was done with a current of 272 A, so that the battery life was judged to be ended
when a voltage after 30 seconds became below 7.2V.
Results are listed in Table 4. A cycle life number of the lead acid battery
of Comparative example 9 is assumed as 100%.
| TABLE 4 |
|
| |
Adding amount of Sb2O3 |
Cycle life number |
| Battery |
(Mass %) |
(%) |
|
| |
| Comparative |
0.05 |
103 |
| example 3 |
| Comparative |
0.1 |
110 |
| example 4 |
| Comparative |
0.2 |
107 |
| example 5 |
| Comparative |
0.3 |
79 |
| example 6 |
| Comparative |
0.4 |
62 |
| example 7 |
| Comparative |
0.5 |
55 |
| example 8 |
| Comparative |
0 |
100 |
| example 9 |
|
Consideration
The lead acid batteries of Comparative examples 3 to 5 were superior to the lead
acid battery of Comparative example 9 in the cycle life performances. It can be
thought that this is owing to the effect of the antimony compound added to the
positive active material. On the other hand, the electrolyte's decrease became
large in proportion to the adding amount of the antimony compound, and the electrolyte's
decrease of the lead acid batteries of Comparative examples 6 to 8 became twice
or more as large as that of the lead acid battery of Comparative example 9. For
this reason, the life performances of the lead acid batteries of Comparative examples
6 to 8 were bad.
Similar results were obtained when Sb
2O
5 was used in
place of the Sb
2O
3.
The lead acid batteries of Comparative examples 3 to 5 were disassembled and
examined after completion of the cycle life test, and the following facts became clear.
In the lead acid batteries of Comparative examples 3 to 5; the positive electrodes
were deteriorated a little, the negative active material shrunk, and the accumulation
of lead sulfate, i.e. so called "sulfation" proceeded, thereby causing the limitation
of the battery life by the negative electrode.
As seen from Comparative examples 3 to 9, the life performance of the positive
electrode can be improved when the antimony compound is added to the positive active
material by 0.05 to 0.2 mass %. Particularly, the most suitable adding amount was
0.1 mass %.
EXAMPLE 13
A lead acid battery was produced as follows.
Production of Negative Electrode
A negative electrode was produced in the same procedures as those of Example
1.
The adding amount of the lignin was 0.2 mass %.
Production of Positive Electrode
A positive electrode was produced in the same procedures as those of Comparative
example 3, except that the adding amount of the Sb
2O
3 was
varied as 0.1 mass %.
Production of Lead Acid Battery
A lead acid battery was produced in the same procedures as those of Example 1.
EXAMPLE 14 & 15
Lead acid batteries were produced in the same procedures as those of Example
13, except that the adding amount of the lignin was varied as 0.4 mass % and 0.6
mass %, respectively. These batteries were named as Examples 14 and 15, in this order.
COMPARATIVE EXAMPLE 10
A lead acid battery was produced in the same procedures as those of Example 13,
except that a negative electrode was produced in the same procedures as those of
Comparative example 2 and a positive electrode was produced in the same procedures
as those of Example 13.
Test 5
The lead acid batteries of Examples 13 to 15 and Comparative example 10 were
subjected to the cycle life tests under the same conditions as those of the test 4.
Results are listed in Table 5. A cycle life number of the lead acid battery
of Comparative example 9 was assumed as 100%.
| |
TABLE 5 |
| |
|
| |
Negative |
|
| |
active material |
| |
|
Lignin |
Adding |
|
| |
|
(Chemical |
amount |
Cycle life number |
| |
Battery |
formula) |
(Mass %) |
(%) |
| |
|
| |
Example 13 |
formula (I) |
0.2 |
125 |
| |
Example 14 |
formula (I) |
0.4 |
142 |
| |
Example 15 |
formula (I) |
0.6 |
130 |
| |
Comparative |
formula (III) |
0.2 |
110 |
| |
example 10 |
| |
|
Consideration
The cycle life performances of the lead acid batteries of Examples 13 to 15 were
superior to those of the lead acid battery of Comparative example 10 by about 25%
to 42%.
The lead acid batteries of Examples 13 to 15 and Comparative example 10 were
disassembled and examined after completion of the cycle life test, and the following
facts became clear.
(1) In the lead acid battery of Comparative example 10, the negative active material
shrunk and the accumulation of lead sulfate, i.e. so called as "sulfation", proceeded
to cause the limitation of battery life by the negative electrode.
(2) In the lead acid batteries of Example 13 to 15, the deterioration of the
negative electrodes as occurred in Comparative example 10 was not recognized. It
can be thought that this is owing to the effect of the lignin.
(3) In the lead acid batteries of Example 13 to 15, the electrolyte's decrease
of them was small as compared with the lead acid batteries of Examples 1 to 4.
As seen from the above-mentioned description, in the lead acid batteries of Examples
13 to 15, the life performance of the positive electrode can be improved because
the antimony compound is added to the positive active material and the life performance
of the negative electrode can be improved too because the lignin of the formula
(I) is added to the negative active material. Consequently, the life performance
of the battery can be improved further. It is preferable that the adding amount
of the lignin ranges from 0.2 to 0.6 mass %. In addition, since the positive electrode
grid made of the lead alloy which does not contain the antimony, the electrolyte's
decrease can be controlled.
Comparing the lead acid batteries of Examples 13 to 15, the lead acid battery
of Example 14 is most excellent in its life performance. For this reason, in Examples
16 to 18, the adding amount of the antimony compound in the positive electrode
was varied using the same negative electrode as that of Example 14.
EXAMPLES 16 to 18
Lead acid batteries were produced in the same procedures as those of Example
14, except that the adding amount of the Sb
2O
3 was varied
as 0.05 mass %, 0.2 mass %, and 0.3 mass %, respectively. Tease batteries were
named as Examples 16 to 18, in this order.
Test 6
The lead acid batteries of Examples 16 to 18 were subjected to the cycle life
tests under the same conditions as those of the test 4.
Results are listed in Table 6. A cycle life number of the lead acid battery
of Comparative example 9 is assumed as 100%.
| TABLE 6 |
|
| |
Adding |
Negative active material |
Cycle |
| |
amount of |
Lignin |
Adding |
life |
| |
Sb2O3 |
(Chemical |
amount |
number |
| Battery |
(Mass %) |
formula) |
(Mass %) |
(%) |
|
| Example 16 |
0.05 |
formula (I) |
0.4 |
133 |
| Example 17 |
0.2 |
formula (I) |
0.4 |
138 |
| Example 18 |
0.3 |
formula (I) |
0.4 |
101 |
|
Consideration
The cycle life performances of the lead acid batteries of Examples 16 to 18 were
superior to those of the lead acid battery of Comparative example 9. Particularly,
the life performances of the lead acid batteries of Examples 16 and 17 were superior
to those of the lead acid battery of Comparative example 11 by about 25% to 42%.
Therefore, as obvious from Examples 14, 16 and 17, the adding amount of the antimony
compound to the positive active material preferably ranges from 0.05 to 0.2 mass %.
The lead acid batteries of Examples 16 to 18 were disassembled and examined after
completion of the cycle life test, and the following facts became clear.
(1) In the lead acid batteries of Example 16 to 18, the deterioration of the
positive electrode were not recognized. It can be thought that this is owing to
the effect of the antimony compound. However, the accumulation of lead sulfate
in the negative active material, i.e. "sulfation", proceeded in proportion to the
adding amount of the antimony compound.
(2) In the lead acid batteries of Example 16 to 18, the electrolyte's decrease
of them was small as compared with the lead acid batteries of Examples 1 to 4.
As seen from the above-mentioned description, in the lead acid batteries of Examples
16 to 18, the life performance of the positive electrode can be improved because
the antimony compound is added to the positive active material and the life performance
of the negative electrode can be improved too because the lignin of the formula
(I) is added to the negative active material. Consequently, the life performance
of the battery can be improved further. Particularly, the life performance can
be improved further more, when the adding amount of the antimony compound ranges
from 0.05 to 0.2 mass %. In addition, since the positive electrode grid made of
the lead alloy which does not contain the antimony, the electrolyte's decrease
can be controlled.
ANOTHER EXAMPLES
(1) The same results were obtained in the above-mentioned Examples, even when
the lignin of the formula (II) was used in place of the lignin of the formula (I),
or even when the lignin of the formula (I) was used in place of the lignin of the
formula (II).
(2) R
1 in the formula (I) or R
1 in the formula (II) is
not limited to the above-mentioned OH or SH. They may be H, COOH, SO
3H,
C
6H
5, COO
-, SO
3-, R
2C
6H
4,
(R
2)
2C
6H
3, or (R
2)
3C
6H
2.
R
2 is at least one member selected from among OH, COOH, SO
3H,
and CH
2SO
3. The same results were obtained in the above-mentioned
Examples even in these cases.
INDUSTRIAL APPLICABILITY
The negative active materials and the lead acid batteries of this application
can be extremely improved in their life performances, so that they can provide
a considerable industrial applicability.
*
