JP6708704B2 - Lead acid battery - Google Patents

Description

The present invention relates to a lead storage battery.

In recent years, electrification of vehicles has rapidly progressed to reduce environmental load, and idling stop vehicles and hybrid vehicles have appeared. Hybrid vehicles include micro hybrid vehicles, mild hybrid vehicles, and strong hybrid vehicles, and relatively inexpensive micro hybrid vehicles and mild hybrid vehicles are becoming more popular.
Lead-acid batteries installed in this type of environment-friendly vehicle are used in a more severe environment than before. For example, a lead storage battery is required to have higher durability and charge acceptability such as an increase in the number of engine starts, power supply to electric components during idling stop, and regenerative charging by braking.

In order to improve the durability of the lead storage battery, it is effective to improve the active material density of the positive electrode plate. This is because the positive electrode active material of the lead storage battery is coarsened by charging and discharging, and the binding of the active material particles is gradually reduced. It is a known fact that this phenomenon is called softening and can be suppressed to some extent by increasing the density of the active material. It is also a well-known fact that the specific surface area is increased by increasing the amount of conductive carbon in the negative electrode in order to improve charge acceptability (see, for example, Patent Documents 1 and 2).

JP, 2013-211205, A JP, 2017-16970, A

However, recently, there is a movement to further increase electric power taken out from a lead storage battery mounted on an environment-friendly vehicle to improve fuel economy. In this case, since the depth of discharge becomes deep, the life of the battery is shortened even if the battery has an increased density of the positive electrode active material.
Therefore, an object of the present invention is to provide a lead storage battery that can achieve both higher durability and charge acceptance.

In order to solve the above-mentioned problems, the present invention provides a lead storage battery that includes a positive electrode plate containing a positive electrode active material and a negative electrode plate containing a negative electrode active material, and uses an electrolytic solution containing dilute sulfuric acid, and has the following formula (1): by contrast effective amount of the active material obtained, the ratio of net sulfuric acid in the electrolyte of 0.45 or more state, and are 0.65 or less, the ratio of the effective amount of the positive electrode active material for an effective negative active material weight is 0.5 or more , and wherein the der Rukoto 0.9 or less.
Effective active material amount=positive electrode active material amount×positive electrode utilization rate/100+negative electrode active material amount×negative electrode utilization rate/100 Equation (1)
The utilization rate is a 5-hour utilization rate (5HR).

Further, in the above structure, the specific gravity of the electrolytic solution of the finished product may be 1.275 g/cc or more and 1.290 g/cc or less.

Further, in the above structure, the positive electrode active material density of the positive electrode plate may be 4.5 g/cc or more, and the negative electrode active material specific surface area of the negative electrode plate may be 0.7 m2/g or more.

According to the present invention, both higher durability and charge acceptance can be achieved.

An embodiment of the present invention will be described below.
When the inventors examined lead acid batteries, they found that when the ratio of pure sulfuric acid to the amount of active active material was 0.45 or more and less than 0.65, excellent durability was exhibited even in deep discharge. It was
The reason for this is that durability and charge acceptance can be maintained during use when the amount of pure sulfuric acid relative to the actual amount of active material actually used is appropriate, not the total amount of active material in the battery. It is speculated that
Here, the amount of pure sulfuric acid is the amount of sulfuric acid (H ₂ SO ₄ ) contained in the electrolytic solution of the lead storage battery.

The amount of effective active material is the total of the amount of effective positive electrode active material and the amount of effective negative electrode active material, and can be represented by the formula (1).
Effective active material amount=positive electrode active material amount×positive electrode utilization rate/100+negative electrode active material amount×negative electrode utilization rate/100 Equation (1)
The utilization rate is a 5-hour utilization rate (5HR).

As a result of further studies, it was found that the durability was further improved when the ratio of the effective positive electrode active material amount to the effective negative electrode active material amount was 0.5 or more and 0.9 or less. The reason for this is presumed that when the amount of effective active material is within this range, the charge balance on the positive electrode side and the negative electrode side is optimal, and the life performance is extended.
The specific gravity of the electrolytic solution after forming the battery case (finished product) is preferably 1.275 g/cc or more and 1.290 g/cc or less. If the specific gravity is less than 1.275 g/cc, the capacity may be insufficient, and a dendrite short circuit is likely to occur after being left overdischarge. On the other hand, when the specific gravity exceeds 1.290 g/cc, charge acceptability may be deteriorated and the deterioration of the positive electrode may be facilitated, which may cause deterioration of durability. The finished product is not limited to the one immediately after the formation of the battery case, and may be in any state of shipping, storing and selling.

Further, it has been found that when the positive electrode active material density of the positive electrode plate is 4.5 g/cc or more and the negative electrode active material specific surface area of the negative electrode plate is 0.7 m ² /g or more, excellent durability is exhibited. It was
Note that the active material density of the positive electrode plate (also referred to as positive electrode active material density) is preferably 4.5 g/cc or more and 5.0 g/cc or less. By setting it in the range, it is possible to improve durability. The density of the positive electrode active material may exceed 5.0 g/cc, but it becomes difficult to secure the capacity. Further, when the positive electrode active material density is less than 4.5 g/cc, the durability is insufficient and the life becomes early.
The active material specific surface area (negative electrode active material specific surface area) of the negative electrode plate is preferably 0.7 m ² /g or more and 0.9 mm ² /g or less. By setting the range, it is possible to improve charge acceptability. The specific surface area of the negative electrode active material may exceed 0.9 m ² /g, but the effect of charge acceptance is saturated. Further, when the specific surface area of the negative electrode active material is less than 0.7 m ² /g, charge acceptability is insufficient and PSOC durability is reduced.

Next, examples of the present invention will be described together with comparative examples. The present invention is not limited to the examples below.

First, the positive electrode plate will be described. Lead powder containing lead monoxide as a main component is mixed with lead oxide, polyester fiber (for example, Tetron (registered trademark)), bismuth, and compound granules containing antimony (hereinafter, referred to as dry mixing), and then water. And kneaded (hereinafter referred to as water kneading), then diluted sulfuric acid was added and kneaded again (hereinafter referred to as acid kneading) to prepare a paste-like positive electrode active material (hereinafter referred to as positive electrode active material paste). Referred to).
The amount of water and the amount of dilute sulfuric acid were previously confirmed by experiments so that the desired positive electrode active material paste density could be obtained. The positive electrode active material paste density can be obtained by filling the positive electrode active material paste in a stainless steel container whose internal volume is known in advance and calculating from the filling weight.

The obtained positive electrode active material paste was filled in a JIS-D size gravity cast substrate (about 47 g/sheet, thickness about 1.3 mm), and diluted sulfuric acid with various specific gravities was uniformly applied to the surface of the electrode plate at a pressure of 0.1 MPa. After being sprayed on, it was passed through a preheated drying oven. After preheating and drying, aging and drying were performed under predetermined conditions to produce a positive electrode plate.

Regarding the negative electrode plate, a JIS-D size gravity cast substrate (about 40 g/sheet, thickness about 1.1 mm) was filled with a lead paste prepared by a known method, passed through a preheating drying furnace, and preheated and dried under predetermined conditions. Aged and dried to prepare a negative electrode plate.

Next, the positive electrode plate 7 and the negative electrode plate 8 are alternately laminated with a polyethylene separator sandwiched therebetween and combined with each other by the cast-on-strap method (also referred to as the COS method) to make the electrodes having the same polarity. Welded to form a plate group, which was placed in a polypropylene (PP) battery case. The pressing force of the electrode plate group was set to about 10 kPa.
Then, the battery case and the lid were heat-sealed by heat sealing to obtain a D23 type liquid lead acid battery, and a battery case was formed by a known method by injecting an electrolytic solution and energizing. The specific gravity of the electrolytic solution after forming the battery case was adjusted to 1.280 g/cc (value converted at 20° C.), and this was set as Example 1.
Regarding the positive electrode active material density and the negative electrode active material specific surface area, values were obtained by disassembling after chemical conversion and analyzing each. For the density of the positive electrode active material, the Archimedes method was used, and for the specific surface area of the negative electrode active material, after grinding the active material in a mortar, it was passed through a sieve with an opening of 355 μm, and the passed-through powder was analyzed by a high-performance specific surface area/pore distribution measuring device ASAP2020. It was measured with a series (Micromeritics).

In comparison with Example 1, the ratio of pure sulfuric acid to the amount of active active material (hereinafter referred to as sulfuric acid ratio X), the ratio of the effective positive electrode active material to the amount of effective negative electrode active material (hereinafter referred to as effective active material ratio Y), Also, a plurality of types of lead storage batteries having different specific gravities (hereinafter, referred to as electrolytic solution specific gravities Z) of the electrolytic solution after the battery case formation (completed product) were prepared, and these were designated as Examples 2-31 and Comparative Examples 1-11. did.
In addition, about Examples 1-21, 24-26, 28-31 and Comparative Examples 1-11, the positive electrode active material density of a positive electrode plate is 4.5 g/cc or more, and the negative electrode active material specific surface area of a negative electrode plate is 0.7 m. ^{It is 2} /g or more.
Each lead acid battery was tested for 5 HR (5 hour rate) capacity and durability, and the test results are shown in Table 1.

The 5HR capacity was measured according to the JIS standard (JIS D 5301 (2006 version)). Specifically, the lead storage battery was placed in a water tank at 25° C.±2° C. and discharged at a current of 10.4 A until the voltage dropped to 10.50 V±2 V. The duration (hour) and the current value (A) were multiplied to calculate the 5HR capacity.

The durability was evaluated by carrying out an idling stop life test according to the battery industry association standard (SBA S 0101 (2014 edition)) while increasing the discharge current. That is, according to the standard, the current of the discharge 1 is I _D =18.3I _20, so if I ₂₀ =3.05A, I _D =18.3×3.05=55.8A, In order to make the conditions more severe, it was set to 66.0 A, which is about 1.2 times. As a specific method, the battery was placed in a gas phase of 25° C.±2° C. (the wind velocity in the vicinity of the battery was 2.0 m/s or less), and the cycle of discharge 1 and discharge 2 and charging was repeated. During the test, after left for 3,600 times for 40 to 48 hours, the cycle was started again, and the test was terminated when it was confirmed that the discharge voltage during the test became less than 7.2V. Also, replenishing water was not performed up to 30,000 times.

The discharge conditions are as follows.
Discharge 1: Discharge under the condition of current value=66A±1A, holding time=59.0±0.2 seconds Discharge 2: Discharge under condition of current value=300A±1A, holding time=1.0±0.2 seconds

The charging conditions are as follows.
Charging voltage value=14.00±0.03V (limit current 100.0±0.5A) 60.0±0.3 seconds

The utilization rate of the positive electrode and the negative electrode was the value obtained in advance by separately preparing a 2V cell separately from the examples and comparative examples.
The 5 HR utilization rate on the positive electrode side was calculated by preparing a 2V cell composed of 7 positive electrode plates and 8 negative electrode plates and having a sufficiently large amount of negative electrode active material compared to the amount of positive electrode active material. The battery case formation and the 5HR capacity were performed in the same manner as above, and the utilization rate of the positive electrode was calculated from the obtained capacity (Ah) by the calculation formula of the formula (2). In addition, since the utilization factor differs depending on the density, a 2V cell was produced with each concentration, and the utilization factor according to each density was determined.
Positive electrode utilization rate=5 HR capacity/(amount of positive electrode active material per cell/4.463)...Equation (2)
The effective positive electrode active material amount can be obtained by multiplying the calculated positive electrode utilization rate by all the positive electrode active material amounts used in the battery.

The utilization rate of 5HR on the negative electrode side was calculated by preparing a 2V cell composed of eight positive electrode plates and seven negative electrode plates and having a sufficiently large amount of positive electrode active material as compared with the amount of negative electrode active material. The formation and the 5HR capacity were performed in the same manner as above, and the utilization rate of the negative electrode was calculated from the obtained capacity (Ah) by the calculation formula of the formula (3).
Negative electrode utilization rate=5 HR capacity/(amount of negative electrode active material per cell/3.865)...Equation (3)
The calculated negative electrode utilization rate can be multiplied by the total amount of the negative electrode active material used in the battery to obtain the effective negative electrode active material amount.

In Example 1, the expected performance was obtained for both the number of cycles and the 5HR capacity. More specifically, the durability required is higher than that required for an environment-friendly vehicle, and the durability and charge acceptance are improved by adjusting the active material density and specific surface area on the positive and negative electrode sides. It was possible to achieve both charge acceptance and charge acceptance.
Table 1 shows the positive electrode active material density [g/cc], the negative electrode active material specific surface area [m ² /g], the sulfuric acid ratio X, the effective active material ratio Y, the electrolytic solution specific gravity Z, the number of cycles, and the 5HR capacity. .. The number of cycles and the 5HR capacity in Table 1 show the respective ratios of the number of cycles and the 5HR capacity when Example 1 was set to 100%.

As shown in Table 1, in Comparative Examples 1 to 11 in which the sulfuric acid ratio X is less than 0.45 or exceeds 0.65, the cycle number is particularly inferior to that of Example 1, and good cycle characteristics are obtained. I couldn't do it.
On the other hand, Examples 1 to 31 in which the sulfuric acid ratio X was in the range of 0.45 or more and 0.65 or less showed excellent cycle characteristics. It is presumed that the reason is that the ratio of pure sulfuric acid to the amount of the active active material was appropriate, and thus the durability of the battery during the cycle test and the charge acceptability were compatible.

Examples 2 to 4, 7 to 9, 12 to 14, 17 to 18, 24 to 26, 28 to 31 showed more excellent cycle characteristics than Example 1. The reason is that the effective active material ratio Y (the ratio of the effective positive electrode active material to the amount of the effective negative electrode active material) was appropriate, so that the charge balance between the positive electrode side and the negative electrode side was appropriate, and the charge acceptance during the cycle test was accepted. It is presumed that it was possible to maintain sex.
Examples 16 and 17 showed relatively excellent cycle characteristics. It is presumed that the reason is that the electrolyte specific gravity Z of the finished product is 1.270 to 1.275, which is lower than those of the other examples, and the charge acceptability is further improved. Also in Example 19, the cycle characteristics were deteriorated. It is considered that this is because the charge acceptability was lowered because the electrolytic solution specific gravity Z was increased too much.

In Examples 1 to 21, 24 to 26, and 28 to 31, the density of the positive electrode active material is 4.5 g/cc or more, and the specific surface area of the negative electrode active material of the negative electrode plate is 0.7 m ² /g or more. When the positive electrode active material density of the positive electrode plate was less than 4.5 g/cc and the negative electrode active material specific surface area of the negative electrode plate was less than 0.7 m ² /g, the proportion of pure sulfuric acid was within the range. Also, the number of cycles and the 5HR capacity were worse than in Example 1.

Example 22 has a positive electrode active material density of 4.4 g/cc, and Example 23 has a positive electrode active material density of 4.4 g/cc and a negative electrode active material specific surface area of 0.6 m ² /g. In Example 27, the negative electrode active material specific surface area of the negative electrode plate was set to 0.6 m ² /g, but by setting the sulfuric acid ratio X, the effective active material ratio Y, and the electrolytic solution specific gravity Z to the values shown in Table 1, The same cycle number and 5HR capacity as in Example 1 were obtained.
Further, in Examples 24 to 26, the positive electrode active material density was set to a relatively high range of 4.7 g/cc to 5.0 g/cc, and the sulfuric acid ratio X, the effective active material ratio Y, and the electrolytic solution specific gravity Z were expressed. By setting the value to 1, the cycle characteristics equivalent to or better than those of Examples 16 and 17 were obtained.
In Examples 28 to 31, the negative electrode active material specific surface area and a relatively high range and 0.9m ² /g~1.3m ² / g, the ratio X, the effective active material ratio Y, and electrolyte specific gravity sulfuric acid By setting Z to the value shown in Table 1, cycle characteristics similar to those of Examples 16 and 17 were obtained.

It should be noted that the above-described embodiment merely shows one aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention. For example, as the configuration of each part such as the positive electrode plate, the negative electrode plate, and the separator that form the lead storage battery, known configurations can be widely applied. Further, the present invention is not limited to the case of applying to a lead storage battery for an idling stop vehicle, and may be applied to a lead storage battery used for various purposes.

Claims (3)

In a lead acid battery including a positive electrode plate containing a positive electrode active material and a negative electrode plate containing a negative electrode active material, and using an electrolytic solution containing dilute sulfuric acid,
To effective amount of the active material obtained by the following equation (1), the proportion of pure sulfuric acid in the electrolyte of 0.45 or more state, and are 0.65 or less,
Effective anode active ratio of the effective amount of the positive electrode active material to a substance weight of 0.5 or more, the lead-acid battery, characterized in der Rukoto 0.9.
Effective active material amount=positive electrode active material amount×positive electrode utilization rate/100+negative electrode active material amount×negative electrode utilization rate/100 Equation (1)
The utilization rate is a 5-hour utilization rate (5HR). The lead acid battery according to claim 1, wherein the specific gravity of the electrolytic solution of the finished product is 1.275 g/cc or more and 1.290 g/cc or less. The positive electrode active material density of the positive electrode plate is 4.5 g/cc or more, and the negative electrode active material specific surface area of the negative electrode plate is 0.7 m. ^Two /G or more, The lead acid battery of Claim 1 or 2 characterized by the above-mentioned.