JPH0831336B2 - Anode plate for sealed lead acid battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of characteristics of a positive electrode plate for a sealed lead-acid battery, particularly improvement of high rate discharge characteristics, over-discharge leaving characteristics, and life characteristics.

2. Description of the Related Art A conventional sealed lead-acid battery electrode plate is formed by filling a paste into a grid that has been cast or expanded and then forming the electrode plate through a chemical conversion process. Therefore, the active material is filled up to the inside of the electrode plate. On the other hand, the grid bone of the grid body made of lead or lead alloy as the grid of the electrode plate for the NS40Z type lead storage battery (JIS type of lead acid battery for automobiles that uses an excess of electrolyte instead of the sealed lead storage battery with limited electrolyte) By replacing a part of the above with a non-conductive or conductive woven or non-woven fabric having heat resistance, acid resistance, and oxidation resistance, there is a material that is lightweight and has less loss of the active material.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, the discharge reaction of a sealed lead-acid battery is a reaction of an anode active material, a cathode active material and sulfuric acid, but since the electrolyte is limited in the sealed lead-acid battery, the discharge characteristics, In particular, the diffusion of sulfuric acid has a great influence on the voltage characteristics. In the conventional electrode plate, the active material is filled up to the inside of the electrode plate, so the diffusion of sulfuric acid cannot follow up to the inside during discharge, and the reaction on the surface of the electrode plate is the main after all, and the active material inside is rarely used. Has become. This tendency becomes remarkable as the discharge current increases and the electrode plate thickness increases. This phenomenon not only affects the discharge characteristics, but also greatly affects the battery life. This is because the active material near the surface is intensively used during discharge, and the active material near the surface becomes mud and falls off. Therefore, the capacity tends to decrease due to a short circuit or a muddy state. In addition, the problem of capacity decrease due to the decrease in adhesion between the active material and the grid due to the expansion of the grid, which is likely to occur in the sealed lead-acid battery, is also an important problem in the conventional electrode plate. More importantly, there is a phenomenon, which is peculiar to a sealed lead-acid battery, in that charging cannot be performed after being left over-discharged. This is a major drawback of the sealed lead-acid battery, and it is considered that the cause is that a high-resistivity layer of lead sulfate is formed at the interface between the lattice and the active material by self-discharge during standing for over-discharge.

Recently, sealed lead-acid batteries for handy cleaners, VTR
As represented by power supplies for (Buitiar),
Significant expansion into home appliances. Therefore, there is a rapid demand for cycle applications with a relatively high rate discharge. In order to meet the demand, it is desired that the active material in the electrode plate is used uniformly and the discharge characteristics, especially the voltage characteristics and the capacity are improved. Moreover, in the case of home appliances, the number of users is unspecified, so reliability is strongly desired, especially if the battery is not used even if it is stopped for a long time after discharge and it is not charged even if it is recharged. It is more difficult to use than batteries. As a matter of course, it is essential to have a stable life in terms of life.

As described above, in order to meet the demand for the sealed lead-acid battery, the conventional electrode plate has the above-mentioned drawbacks and does not have satisfactory characteristics.

INDUSTRIAL APPLICABILITY The present invention improves the discharge capacity, discharge characteristics, over-discharge leaving characteristics and current life of a sealed lead-acid battery that allows the active material in the anode plate to be uniformly used and can be easily charged even in an over-discharge standing state. The purpose is to do.

Means for Solving Problems The present invention is characterized in that, in order to solve the above problems, a non-woven fabric made of carbon fibers holding an electrolytic solution is interposed between two lattices holding an anode active material. It is a thing.

Action Since an anode plate is prepared using a three-layer structure substrate of a lattice, a carbon nonwoven fabric, and a lattice, the active material layer has a three-layer structure of the carbon nonwoven fabric containing the active material and the electrolyte, and the active material. Sulfuric acid is supplied from the outside of the electrode plate and from the carbon nonwoven fabric in the center of the three-layer substrate, and the utilization in the center of the electrode plate is higher than that of the conventional anode plate, so that it can be used uniformly throughout the electrode plate. Further, since the carbon nonwoven fabric has conductivity, a charging current can flow through the carbon nonwoven fabric even if a high resistance layer of lead sulfate is formed at the interface between the grid and the active material after being left overdischarge. Therefore, the charge recovery property is far superior to the conventional anode plate.

Examples Details of the present invention will be described with examples. FIG. 1 shows a substrate having a three-layer structure of a lattice, a carbon nonwoven fabric, and a lattice of the present invention. Reference numeral 1 is a lattice, and 2 is a non-woven fabric made of carbon fine fibers. FIG. 2 is a plan view of a grid, and FIG. 3 is a cross-sectional view of an anode plate of the present invention in which a substrate having a three-layer structure is filled with a paste and formed into an active material. 3 is an active material. The anode plate of this structure had a size of 40 mm × 100 mm × 3 mm. The breakdown of the thickness is a grid thickness of 1.5 mm x 2 and a carbon nonwoven fabric of 0.4 mm x 1. First, the carbon nonwoven fabric 2 was inserted between the lattices 1 and 1 and the ears of the lattices 1 and 1 were integrally joined by arc welding. After that, the paste was filled from both sides, dried and then subjected to a usual chemical conversion process to obtain an anode plate. The amount of active material at that time was 28 g. This anode plate 1 and normal cathode plate 2
A sealed lead-acid battery was created using the sheets. The electrolyte has a specific gravity of 1.
320 ml of sulfuric acid was used, and a normal retainer was interposed between the cathode and anode plates. For comparison, a conventional sealed lead-acid battery of exactly the same type other than the anode plate was also prepared by using a conventional type conventionally used product as an anode plate, a grid thickness of 3.0 mm, and an active material amount of 34 g. Hereinafter, a battery using a conventional anode plate (hereinafter referred to as “conventional battery”) is referred to as b, and a battery using the anode plate of the present invention (hereinafter referred to as “battery of the present invention”) is referred to as a. In Figure 4
The test results of 2 A discharge are described. As can be seen from the figure, the battery a of the present invention exhibits much better voltage characteristics than the conventional battery b, and the difference is particularly large at the end of discharge. This corresponds to the fact that the supply of the electrolytic solution is stably performed until the end of the discharge, and the reaction occurs in the entire anode plate.
Figures 5 and 6 show the reaction distribution in the anode plate after 2A discharge, which is the proof. Here, attention is paid to S of PbSO ₄ which is a reaction product, and the amount of PbSO ₄ is shown in correspondence with the Kα intensity of S. FIG. 5 shows the reaction distribution of the conventional anode plate, where the reaction distribution is concentrated near the surface of the anode plate, and the central portion is less utilized. On the other hand, it is understood that the reaction distribution of the anode plate of the present invention shown in FIG. 6 has the electrolytic solution at the center, and therefore the reaction is almost entirely performed. Further, in order to understand the characteristics of the anode plate of the present invention, the capacity recovery property and the life characteristics after being left over discharge were examined. Regarding the capacity recovery property, after discharging 2 A, constant voltage charging of 2.45 V was carried out for 8 hours, and constant resistance discharging with resistance of 5 Ω was carried out continuously for 5 days. After that, leave it under the condition of ambient temperature of 45 ℃ for 14 days, and
2.45V constant voltage charging was performed for 8 hours. After the end of charging, the battery was discharged at 2A and compared with the initial capacity.

FIG. 7 shows the capacity recovery rates of the conventional battery b and the battery a of the present invention. As is clear from the figure, the battery a of the present invention has a better capacity recovery rate than the conventional battery b. The reason for this is that there is a conductive carbon nonwoven fabric in the center of the anode plate, so even after a high-resistance layer exists at the interface between the grid and the active material, a current easily flows from the carbon nonwoven fabric to the active material and the battery is charged after overdischarging. This is probably because the acceptability is good. The life test was performed by discharging 2A for 30 minutes and charging 0.23A for 5 hours. The temperature is 20 ° C. 8th
The figure shows the results at 100 cycles. No significant difference is observed at the time of 100 cycles, but the capacity of the conventional battery b gradually decreases. In contrast, the battery a of the present invention has no change from the initial state at this point. The capacity was confirmed every 20 cycles with a complete discharge of 2A. Regarding the life, we have not confirmed a slight difference at the time of 100 cycles, but the discharge distribution is uniform and there is no local deterioration of the active material. Even if peeling occurs at the interface, the presence of carbon nonwoven fabric in the center allows current collection, so it seems that there will be a difference after 100 cycles.

EFFECTS OF THE INVENTION As described above, the present invention is characterized in that a nonwoven fabric made of carbon fiber holding an electrolytic solution is interposed between two lattices holding an anode active material, and the positive electrode plate for a sealed lead-acid battery is characterized. Therefore, the electrolytic solution is supplied not only from the outside of the electrode plate but also from the inside of the electrode plate to the active material of the anode plate used in the sealed lead acid battery in which the electrolytic solution is originally limited. Therefore, the active material can be uniformly used over the entire anode plate, and the discharge characteristics, capacity, and life can be improved, and the capacity recovery of the sealed lead-acid battery after over-discharging and the decrease in capacity due to expansion of the anode grid are improved. It is possible.

[Brief description of drawings]

FIG. 1 is an explanatory view of a substrate used in the present invention, and FIG.
FIG. 3 is a plan view of a grid used for the substrate of FIG. 3, FIG. 3 is a cross-sectional view of the anode plate of the present invention, and FIG. 4 is a characteristic comparison curve line of terminal voltage and discharge time of the battery of the present invention and a conventional battery. FIG. 5 is a reaction distribution diagram of a conventional anode plate, FIG. 6 is a reaction distribution diagram of the anode plate of the present invention, FIG. 7 is a comparative characteristic diagram of capacity recovery rates of the battery of the present invention and a conventional battery, and FIG. FIG. 6 is a characteristic comparison curve diagram of the relationship between discharge duration and charge / discharge cycle of the battery of the invention and the conventional battery. 1: lattice, 2: carbon non-woven fabric, 3: active material, a: battery of the present invention,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hayakawa et al. ▲ Ku ▼ Beauty, 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Within Shinjin Todenki Co., Ltd. (72) Inventor Akio Komaki Nishishinjuku, Shinjuku-ku, Tokyo 2-1-1 No. 1 Shinshin Todo Electric Co., Ltd. (72) Inventor Toshio Uchida 832 Horiguchi, Katsuta City, Ibaraki Prefecture 2 2 Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Shogo Morimoto 832 Horiguchi, Katsuta City, Ibaraki Prefecture No. 2 Hitachi, Ltd. Hitachi Research Laboratories collegiate body Judge Yoshiyuki Nishi Judge Judge Hideyuki Ono Judge Judge Asahi Aizawa (56) References JP-B-52-29809 (JP, B2)

Claims (1)

[Claims] 1. A positive electrode plate for a sealed lead-acid battery, characterized in that a nonwoven fabric made of carbon fiber holding an electrolyte is interposed between two grids holding an anode active material.