JPH0234757Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to improving the performance of lead-acid batteries.

Prior Art In general, an anode plate lattice body for a lead-acid battery has a simple lattice structure. This lead grid is filled with paste, and an uncured board is created through aging and drying processes.
This uncured plate is chemically converted in dilute sulfuric acid to obtain a cured plate as an active material. The anode and cathode prepared plates are separated through a separator, and the electrode plate group is assembled to form a battery. The lead lattice bodies of the untreated board and the treated board not only serve as a holder for both the anode and cathode active materials, but also serve as a current collector.

In conventional liquid lead-acid batteries that contain sulfuric acid as an electrolyte, sulfuric acid is heavier than water, so when it is made into an aqueous solution, the sulfuric acid settles further down, resulting in a stratification phenomenon in which the sulfuric acid concentration is high at the bottom of the battery and low at the top. . In order to reduce the difference in sulfuric acid concentration between the upper and lower parts of the battery due to the stratification of the electrolyte sulfuric acid, charging is performed at 115 to 130% of the discharge amount, and stirring is performed using hydrogen and oxygen gas generated at the end of charging. It's on.

Problems that the invention aims to solve When stirring the electrolyte using the gas generated at the end of charging, the gas generation position is not fixed, and it is not sufficient to eliminate the difference in sulfuric acid concentration between the upper and lower parts of the electrolyte. do not have. In lead-acid batteries in actual use, there is always a difference in sulfuric acid concentration between the top and bottom of the battery, and the concentration tends to be higher in the bottom than in the top.

The discharge capacity of a lead-acid battery is greatly affected not only by the anode active material and the cathode active material, but also by the sulfuric acid concentration of the electrolyte. In general, when active materials with the same properties are used, discharge characteristics such as discharge duration and discharge voltage improve as the sulfuric acid concentration of the electrolytic solution increases. This also applies to the same electrode plate in an electrolyte with a difference in sulfuric acid concentration between the upper and lower parts of the battery; charge and discharge reactions occur more easily in the lower part of the plate, where the concentration is higher, than in the upper part, resulting in non-uniformity within the plate. In the case of the anode plate, the deterioration of the anode active material in the lower part takes priority. Local deterioration due to non-uniform reaction is one of the causes of internal short circuits at the bottom and sides of the battery.

On the other hand, lead sulfate produced by discharging in a battery with a high sulfuric acid concentration has large crystals and therefore has poor chargeability.

As described above, the non-uniformity of the sulfuric acid concentration within the battery is an important factor in the performance deterioration of lead-acid batteries.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a button-shaped component made of an alloy composition with low hydrogen and oxygen generation overvoltage attached to the lower part of the electrode grid.

The excess electricity at the end of charging is absorbed by conductors with low resistance (21×10 ^-6 Ωcm for lead, 20× for lead alloys containing copper).
A current of less than 10 ^-6 Ωcm (10 ² Ωcm for lead dioxide) flows and is used for water decomposition, which tends to generate hydrogen and oxygen gas from near the button-shaped parts.

Function This invention uses a button-shaped part that makes it easier for gas generated at the end of charging to be generated mainly from the bottom of the grid, thereby promoting stirring of the electrolyte and making the concentration of sulfuric acid in the electrolyte more uniform between the top and bottom of the battery. It can be done.

Example An embodiment of the present invention will be described.

The dimensions of the grid body 1 used in this invention are 130 mm in height.
The width is 146mm and the pressure is 3.5mm. The button-shaped part 2 attached to the lower part of the lattice body is circular, and the wall thickness is 3.
mm, with four holes 3 drilled therein, the center of which is welded to the grid body 1 by electric welding. The alloy composition of the grid body 1 is SB3% balance lead, whereas button-shaped component 2 is SB5.0%, Cu1.0% balance lead.

Figure 2 shows the change in the electrolyte sulfuric acid specific gravity (20°C) in the height direction after charging the lead-acid battery.
In the conventional product, there is a large difference in the specific gravity of sulfuric acid between the upper and lower parts of the current, and a so-called stratification phenomenon of sulfuric acid is observed, but the product of the present invention has a button-shaped part 2 at the bottom of the grid.
When using the grid body 1 equipped with the sulfuric acid, although the difference in sulfuric acid specific gravity still exists, the difference has become smaller.

FIG. 3 shows the results obtained by analyzing lead sulfate (PbSO ₄ ) generated in the anode active material after discharging for one hour at a discharge current of 0.6C. In the conventional product, there is a large difference in the amount of _PbSO4 generated at the top and bottom of the battery, but in the product of the present invention, this difference is small.

With conventional products, the electrolyte sulfuric acid cannot be sufficiently stirred due to the gas generated at the end of charging, and the electrolyte sulfuric acid remains extremely stratified before proceeding to the _next discharge. A large difference in quantity is observed. For this reason, non-uniform reaction occurred within the electrode plate, but in the case of the product of the present invention, the difference in the amount of PbSO ₄ was small.

Effects of the Idea As described above, by providing the button-shaped part attached to the lower part of the grid body to promote gas generation, the gas generated at the end of charging can be generated preferentially from the lower part. Therefore, the electrolytic solution sulfuric acid can be stirred more thoroughly than conventional products, and by reducing the concentration difference between the upper and lower parts of the battery,
It becomes possible to cause a charging/discharging reaction in the entire electrode plate. That is, the reaction is no longer concentrated in a specific electrode plate part, and the charge/discharge reaction is carried out by the entire electrode plate, which suppresses deterioration of the active material and has the effect of extending the life of the lead-acid battery.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts showing one implementation of the present invention, Figure 2 is a curve diagram showing the stratification phenomenon of electrolyte specific gravity after charging, and Figure 3 shows the lead sulfate distribution in the electrode plate area after discharge. FIG. 1 is a grid, 2 is a button-shaped part, and 3 is a hole.

Claims (1)

[Scope of utility model registration request] In a lead-acid battery containing an electrolytic solution of sulfuric acid and consisting of an anode plate and a cathode plate group separated through a separator, an alloy with a small hydrogen generation overvoltage or oxygen generation overvoltage is placed at the bottom of the grid of the anode plate or cathode plate. A lead-acid battery characterized by having a button-shaped part attached.