JPS61114471A - Positive plate of clad type lead storage battery - Google Patents

Abstract

PURPOSE:To extremely improve the discharging characteristic of a clad type positive plate by filling a mixture, in which graphite having large anisotropy is added to lead powder, into a tube with density under 2.7g/cm<2>. CONSTITUTION:To exhibit excellent advantages, it is necessary to set the filling density of mixture of lead powder and anisotropic graphite under 2.7g/cm<2>. Further, the additive volume of anisotropic graphite is suitable for the range of 0.5-5wt%, and particularly the advantages of performance improvement to the additive volume is excellent in the range of 0.5-2.0wt%. Furthermore, either naturally anisotropic graphite, but the graphite too fine in grain diameter has small advantages, and therefore it is better to have the grain diameter of about 350-1200mum. Whereby, it is possible to extremely improve the discharging characteristic of a clad type positive plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of a clad type lead battery positive electrode plate (hereinafter referred to as a clad type positive electrode plate).

[Problems to be solved by conventional technology/invention] The clad type positive electrode plate is made of a porous tube made of glass fiber or acid-resistant synthetic m91, etc., and a lead alloy core is placed in the center of the lattice, which is covered with lead powder. After filling, soaking, chemical formation, etc. process! It will be built. The tube prevents the active material from falling off, so it has a longer lifespan than a paste-type positive electrode plate.

In order to improve the discharge performance of a clad positive electrode plate, it is necessary to increase the utilization rate of the positive electrode active material.

When a large amount of lead powder is filled into a tube of a certain volume (high packing density), the density of the active material becomes high, so the active material utilization rate becomes low. Therefore, from the point of view of active material utilization, it is preferable that the packing density of lead powder is low, but if the packing density is too low, the bonding between active material particles and the active material and the core metal, which is a current collector, will be poor, resulting in extremely poor packing density. Since the chemical formation property and discharge performance of the plate deteriorate, it has been difficult to improve the discharge performance.

[Means for Solving the Problems] The present invention solves the above-mentioned problems by adding highly anisotropic graphite to lead powder, and provides a clad positive electrode plate with excellent discharge performance. be.

That is, when highly anisotropic graphite is anodized in sulfuric acid,
This method takes advantage of the fact that sulfuric acid penetrates between graphite layers and expands, creating a graphite interlayer compound that has better conductivity than the original graphite. The anisotropic graphite expands during charging of the battery and strengthens the bond between the active material particles and between the active material and the core metal. A board is obtained.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

1.0w of anisotropic Great Black 10 (particle size ioo~1200μl) was added to ordinary lead powder consisting of molten O (approximately 75%, remainder).
t% of the mixture was added and mixed well, and the mixture was filled into a clad grid body having a tube diameter of 9ffilll with various packing densities. Next, rare li7 with ratio i 1.10! The filled horizontal plate was immersed in acid for 24 hours and then dried at 50°C for 24 hours.

A test battery with a nominal capacity of 1i124Ab (5HR) was assembled using the unformed clad positive electrode plate that had been oversized in this way, and after carrying out cell formation, a 5HR discharge test was conducted. For comparison, a conventional product to which no anisotropic graphite was added was also tested. The test results are shown in the figure.

In the figure, △ indicates a positive electrode active material in 5HRM battery using a clad positive electrode plate according to the present invention.
and the packing density of lead powder. B shows the results of a similar test using a conventional product.

In A, the lower the packing density of the mixture of lead powder and anisotropic graphite, the higher the positive electrode active material utilization rate, and a maximum active material utilization rate of 53% was obtained. Conventional product B has a utilization rate of about 35% at most, which shows how superior it is. On the other hand, in conventional product B, the utilization rate of the positive electrode active material decreased at a packing density of 2.7 s/- or less.

When the positive electrode plate after chemical formation was disassembled and examined, chemical formation progressed well at all packing densities in A, in which anisotropic graphite was added to lead powder according to the present invention, and the PbO2 content was 85%.
That was it. Furthermore, even when the packing density was low, the active material inside the tube was tightly packed, and there were no gaps at all within the active material or between the active material and the core metal. On the other hand, in the positive electrode plate of conventional product B with a low packing density, there are parts where gaps are created within the active material or between the active material and the core metal, and in such places the active material remains unformed and Pb O2 was also only 50-60%. This is considered to be the reason why the utilization rate of the positive electrode active material decreased in the conventional product B clad type positive electrode plate with a packing density of 2.71/1211 or less. When the packing density was greater than 2.71/a+l, the utilization rate of the positive electrode active material did not improve even if anisotropic graphite was added to the lead powder. This is because the active material is densely packed, so there is no room for the anisotropic graphite to expand, and the tube allows the anisotropic graphite to expand.
This is because j can be suppressed. Therefore, in order to exhibit the swelling effect of the present invention, the packing density of the mixture of lead powder and anisotropic graphite must be 2.7 s/- or less. Note that the appropriate amount of anisotropic graphite added is in the range of 0.5 to 5 wt%, and in particular, the effect of performance improvement relative to the added amount was significant at 0.5 to 2.0 wt%. In addition, the anisotropic graphite may be either natural or artificial, and if the particle size is too small, the effect will be small;
It was found that a thickness on the order of μm is good.

[Effect of the invention 1] As detailed above, based on the present invention, by filling a tube with a mixture of lead powder and graphite with a large anisotropy at a density of 2.7 s/cnf or less, a clad type The discharge performance of the positive electrode plate can be significantly improved, and the industrial value of the present invention is extremely large.

[Brief explanation of drawings]

The figure is a characteristic diagram showing the positive electrode active material utilization rate of batteries using the clad type lead battery positive electrode plate according to the present invention and the clad type lead battery positive electrode plate according to the conventional method.

Claims (1)

[Claims] 2.7g of a mixture of lead powder and large anisotropic graphite added
A positive electrode plate for a clad lead-acid battery characterized by being filled with a density of /cm^2 or less.