JPH02109263A - Lead-acid battery - Google Patents

Abstract

PURPOSE:To increase energy density by adding liquid absorbing fine powder and acid-resistant hollow fibers to a negative plate. CONSTITUTION:0.01-10wt.% liquid absorbing fine powder of at least one selected from the group of silicon oxide, aluminium oxide, titanium oxide, and carbon and 0.01-5.0wt.% acid-resistant hollow fibers 1 of at least one selected from the group of polyethylene, polypropylene, and polysulfone in which many holes 2 or grooves are passed through from the surface are added to a negative active material. The utilization of the negative active material is substantially increased, and high rate overcharge performance and energy density are improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a negative electrode plate for lead-acid batteries, which improves the utilization rate of the negative electrode active material and the ability to absorb oxygen gas generated from the positive electrode during charging, and improves the efficiency of lead-acid batteries. The aim is to reduce weight and improve high-rate charging characteristics.

It also completely prevents shrinkage of the active material and greatly improves the cycle life of lead-acid batteries.

The charging/discharging reaction of a conventional lead-acid battery is shown by the following equation, and the charging/discharging reaction of the negative electrode involves repeated changes in metallic lead and lead sulfate.
Due to this discharge, the particles of the negative electrode active material become coarse and shrink, and the specific surface area decreases, which tends to decrease the utilization rate.

To prevent this, conventionally, barium sulfate was added as an additive to lead powder, which is mainly lead oxide, which is the raw material for the negative electrode active material.
Measures were taken by adding sodium ligninsulfonate and acid-resistant polymer fibers.

However, these additives alone have not been able to sufficiently meet the characteristics required of recent lead-acid batteries, such as high rate charge/discharge characteristics of energy density (wh/2), cycle life characteristics, etc.

Problems to be Solved by the Invention As mentioned above, in the negative electrode of a lead-acid battery, the particles of the active material become coarse due to repeated charging and discharging reactions, and the utilization rate decreases as the electrode plate contracts. there were.

Due to this shrinkage, the ability to absorb oxygen gas during charging, which is an important characteristic for sealed lead-acid batteries, is significantly reduced, and the electrode plates shrink, resulting in a decrease in group pressure, which causes the active material of the positive electrode to fall off, and the cycle is interrupted. The problem was that the lifespan was shortened.

The present invention solves the above problems and aims to improve the energy density (wh/Kp) of lead-acid batteries.

In order to solve all of the problems described in Means for Solving the Problems, the present invention provides 0.01 to 10 wt% of liquid-absorbing fine powder of one or more of silicon oxide, aluminum oxide, titanium oxide, and carbon. , and hollow fibers of one or more types of polyethylene, polypropylene, and polysulfone with a durability of 0.01 to 5. owt
% added to the negative electrode active material.

Function The present invention is designed to increase the effective surface area of the active material obtained by adding the liquid-absorbing fine powder to the active material when mixing the negative electrode active material paste and absorbing water and sulfuric acid to expand its volume. This increases the utilization rate, and furthermore, by including hollow fibers, the diffusion of oxygen gas into the inside of the negative electrode plate can be completely improved.

In addition, by mixing all of the liquid-absorbing fine particles in the active material, the shrinkage and deterioration of the negative electrode plate is completely suppressed, and the drop in group pressure, which is thought to be the cause of the deterioration of the cycle life of sealed lead-acid batteries, is completely reduced, and the positive electrode active material This means that all deterioration caused by falling off can be significantly improved.

Example 1 An example of the present invention will be fully described below. Figure 1 shows a complete schematic diagram of a hollow fiber, and Figure 2 shows the capacity increase rate of a negative plate manufactured by adding all the calorific agents according to the present invention, based on the capacity of a negative plate manufactured using a conventional paste formulation. show. The vertical axis is the capacity increase rate, and the horizontal axis is the amount of fine powder added. In this case, the amounts of hollow fibers added, ido and swt%, are constant, and the amounts of various fine powders added are changed in stages.

The hollow fiber 1 is made of polyethylene and has an inner diameter of 50 μm.

A material having an outer diameter of 10011 m and a length s and ommO having numerous pores 2 with an average diameter of 1.0 μm was used, and the fine powder had an average particle diameter of 2011 m.

0.5 wt% hollow fibers in the additives shown in Figure 2, 5 in2 fine powder and TiO, i total 3. owt
A negative electrode plate A with a total additive and a conventional negative electrode plate B were made with a constant thickness, and each negative electrode plate was used to achieve a capacity of 2 and an OAh.
We manufactured all cathode absorption type sealed lead-acid batteries with a voltage of 12V. The former is all batteries and the latter is battery B.

This battery was manufactured under the same conditions except for the additive for the negative electrode plate.

In order to understand the high rate overcharging characteristics of the battery and battery B, the set voltage at the time of overcharging was set at 14. Set to TV, 0.5
FIG. 3 shows the results of overcharging for one week at various charging currents up to 2.0 OA. The vertical axis shows the liquid reduction amount, and the horizontal axis shows the total charging current.

In a battery with excellent overcharging characteristics, no hydrogen gas is generated during overcharging, only oxygen gas is generated, but the generated oxygen gas is absorbed by the negative electrode, and the internal pressure of the battery is maintained at a nearly constant equilibrium pressure. . However, in batteries with insufficient overcharging characteristics, the internal pressure of the battery rises above the operating pressure of the safety valve due to hydrogen gas generated by electrolysis of water in the electrolyte and oxygen gas not absorbed by the negative electrode, causing the safety valve to close. When activated, the hydrogen gas and oxygen gas are discharged from the safety valve to the outside of the battery. As a result, the amount of water in the electrolyte decreases.

The amount of superposition of the battery before and after the overcharge test corresponds to the amount of liquid reduction.

According to FIG. 3, it can be seen that the battery of the present invention had less liquid loss than the conventional batteries B and J, and the overcharge characteristics were improved due to the improved characteristics of the negative electrode.

Further, FIG. 4 shows the cycle characteristics of the samples, which were conducted at room temperature of 25° C. under the conditions below the photodischarge conditions.

The vertical axis is the capacity, and the horizontal axis is the number of cycles.

・Charging conditions Constant voltage charging: Photoelectric current - 800 ED Human setting voltage - I J7 V Charging time - 6 hours ・Discharging conditions: Discharge current - 1, QA Cut voltage = 10.5 V According to Figure 4, nominal capacity 1 , 2 If the number of cycles until 50 Ah is reached is considered as the lifespan, battery life is 1100 cycles and battery B is 690 cycles, and by using the negative polarity sound of the present invention, the cycle characteristics can be improved by about 60%. It is shown that.

Furthermore, the energy density (w
h/niri) are 34.1 and 31.9, respectively, and the product of the present invention has an energy fraction (wh,
l Ky ).

Effects of the Invention According to the present invention, the high rate overcharge characteristics, cycle life characteristics, and energy density (wb, /9)' can be significantly improved by significantly improving the utilization rate of the negative electrode plate active material. It will be done.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a hollow fiber used as one of the additives of the present invention, and Figure 2 shows the rate of increase in capacity when the entire electrode plate with a constant thickness is manufactured using the negative electrode active material of the present invention. FIG. 3 and FIG. 4 are diagrams showing the effect of improving high rate overcharge characteristics and cycle life when applied to a sealed lead-acid battery. 1... 1 empty fiber, 2... hole. Name of agent: Patent attorney Shigetaka Awano (1 person)
River Meadow F℃

Claims (3)

[Claims] (1) A lead-acid battery comprising a positive electrode plate, a negative electrode plate, a separator, and an electrolyte, characterized in that liquid-absorbing fine powder and acid-resistant hollow fibers are added to the negative electrode plate. (2) The amount of liquid-absorbing fine powder added is 0.01 to 10 wt%
and the amount of acid-resistant hollow fiber added is 0.01 to 5.0.
The lead-acid battery according to claim 1, which is wt%. (3) The liquid-absorbing fine powder is one or more of silicon oxide, aluminum oxide, titanium oxide, and carbon, and the acid-resistant hollow fiber is polyethylene, polypropylene,
The lead-acid battery according to claim 1, which is made of one or more types of polysulfone and has a plurality of holes or grooves penetrating the inside and surface of the hollow fiber.