JP2008300216A - Lead-acid battery having low-gelation electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead-acid battery having a low-gelation electrolyte. <P>SOLUTION: This lead-acid battery includes: a plurality of positive electrode plates and negative electrode plates alternately arranged; a plurality of separation plates arranged between the positive electrode plates and the negative electrode plates; and the low-gelation electrolyte containing diluted sulfuric acid, and silica particles substantially in a range of 0.1-0.3% of the weight of the electrolyte. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to lead acid batteries, and more particularly to an improved control valve lead acid battery having a low gelled electrolyte.

  Lead acid batteries developed in the late 1800s are the first commercially available batteries. Rechargeable lead acid batteries were developed in the 1950s and have become the most widely used batteries around the world. The discharge chemical reaction of a lead acid battery is represented by the following formula.

PbO ₂ + Pb + 2H ₂ SO ₄ → 2PbSO ₄ + 2H ₂ O
Lead acid batteries are still widely used today because they provide high or low current over a wide temperature range and have good lifetime and life cycle. They are also relatively inexpensive to manufacture and purchase. Another advantage of lead acid batteries is that they come in a variety of shapes and sizes, from home use to large batteries used in submarines.

  A control valve type lead acid battery (VRLA) is a kind of lead acid battery. The VRLA has a container provided with a positive electrode plate, a negative electrode plate, a separator (separator), an electrolyte, and a one-way control valve. The control valve prevents external gas from entering the battery, causing oxygen to react with the electrode plate, causing internal discharge, and discharging gas from the inside of the battery when the internal pressure exceeds a certain value. It has the function to do. Please refer to FIG. FIG. 1 is a cross-sectional view of a conventional lead acid battery. As shown in FIG. 1, the lead acid battery 10 includes a plurality of positive plates 12 and negative plates 14 provided alternately, separators 16 provided between adjacent plates, and an electrolyte (not shown). Prepare. The positive electrode plate 12 and the negative electrode plate 14 respectively convert a lead grid coated with a positive electrode active material such as lead oxide into the positive electrode plate 12 and a lead grid coated with a negative electrode active material such as lead powder into the negative electrode plate 14. Manufactured by chemical conversion process.

  Normally, in a VRLA battery, the electrolyte does not flow freely. With such a non-fluidic electrolyte in VRLA, the gas generated at one electrode can reach the other electrode during discharge. As a result, the oxygen gas can move in the battery, which is reduced on the surface of the negative electrode plate and returned to the battery electrolyte. Alternatively, the non-fluidity of the electrolyte avoids the risk of leaking strong acid and corrosive liquid electrolytes.

  There are two main categories of methods that make electrolytes difficult to flow in lead-acid batteries: adsorption and gelation. U.S. Pat. No. 4,871,428 uses a glass mat separator made of glass fiber to make the liquid electrolyte non-fluidized by adsorption and firmly adhere to the plate, thereby providing a good initial electrolyte. Methods for securing plate contact and obtaining high energy efficiency are listed. However, due to the initial contact between the glass mat separator and the electrode plate, a needle-like dendrite is easily formed on the negative electrode plate, and then a tunnel-shaped passage that contacts the positive electrode plate grows through the adjacent separator plate pore. Finally, the battery will be short-circuited.

  U.S. Pat. No. 4,317,872 lists another method of reacting sulfuric acid and silica particles to de-fluidize the electrolyte to form a gel electrolyte. However, the gel electrolyte has a problem that various electrical characteristics such as high internal resistance, low energy capacity, and low cycle characteristics are inferior. In addition, the gel electrolyte easily contracts, and the contact between the gel electrolyte and the active material on the electrode plate may be hindered. Furthermore, the gel having a high initial viscosity is difficult to be injected into the battery container, and there is a problem that the holes of the electrode plate cannot be effectively filled.

The US Patent No. 4,889,778, and the general formula _{[Y 2 O]. X [} SiO 2] .nH 2 O to about 30 percent by weight of alkali metal polysilica of water-soluble colloidal dispersant, sulfate A thixotropic gel electrolyte made of a mixture prepared by mixing 1 to 3 in a volume ratio of 1 to 3 is listed. x is in the range of about 20 to 350, Y is an alkali metal, and n is the number of moles of water. Further, US Patent Publication No. 2005/0042512 lists lead acid battery electrolytes containing sulfuric acid having a specific gravity of 1.250 to 1.280 and silica particles having a concentration of between 2 and 15 by weight percentage. . At least 10% by weight silica particles are undried precipitated silica slurry.

Although the prior art shows an improved method for preparing a gel electrolyte that facilitates filling into a container, the lead electrolyte battery of a gel electrolyte system has an increase in internal electrical resistance and activity during discharge. The overall electrical properties are still inferior to those composed of ordinary liquid electrolytes due to the reduced energy capacity caused by the decrease in electrolyte material and potential shrinkage problems due to high silica content. Yes.
U.S. Pat. No. 4,317,872 U.S. Pat. No. 4,871,428 U.S. Pat. No. 4,889,778 US Patent Publication No. 2005042512

  In order to improve the above-mentioned problems, an object of the present invention is to provide a VRLA battery based on a low-gelling non-flowable electrolyte.

  In the present invention, the low gelled electrolyte of the lead acid battery has dilute sulfuric acid and silica particles that substantially account for 0.1% to 3% of the weight of the electrolyte. The silica particles are fumed silica particles.

  The present invention further provides a lead acid battery having a low gelled electrolyte. The lead-acid battery includes positive and negative plates that are alternately installed, a separator provided between the positive and negative plates, and a low gelled electrolyte. The low gelled electrolyte has dilute sulfuric acid and silica particles substantially occupying 0.1% to 3% of the weight of the electrolyte. The silica particles are fumed silica particles.

  The lead acid storage battery having a low gelled electrolyte according to the present invention has features such as low internal resistance, fast chargeability, high energy density, and no problem of electrolyte shrinkage. It is particularly suitable as a cost-effective battery for applications requiring a high charging rate and high energy capacity.

  These and other objects of the present invention will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment illustrated in the drawings.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the present invention.

  The present invention has been made on the basis of the discovery of a new method for defluidizing the electrolyte of a lead acid battery, particularly a control valve lead acid (VRLA) battery. In the examples of the present invention, the low gelling electrolyte was prepared by mixing sulfuric acid having a specific gravity of 1.28 to 1.34 and a small amount of silica particles, of which the silica particles were substantially electrolytes. In the range of 0.1% to 3%, desirably 0.5% to 1%.

  Initially, the electrolyte has a low viscosity and can flow freely over a long period of time. However, if the lead acid battery is charged and discharged a few times, a more solid, locally pasted gel mass will begin to form in the entire electrolyte, especially on the surface of the glass mat in contact with the electrode plate. It is observed that it is likely to occur in Moreover, the electrolyte which became the two-phase mixture of this invention can return most to the original liquid phase under fast charge conditions. In practice, the entire electrolyte changes to a more solid paste gel during discharge after repeated discharge / charge cycles.

  Depending on the type and amount of silica particles used, the low gelled electrolyte will be substantially transparent or slightly hazy. When fumed silica is used, the resulting electrolyte is slightly hazy and its turbidity increases slowly with time. Examples of suitable fumed silicas include Degussa's AEROSIL® 200, 200V, pre-dispersed AERODISP® W7520 (ammonia stabilized), or W7520N (sodium hydroxide stabilized). .

  No special mixing equipment is required. Various conventional mixing equipment such as a propeller stirrer and a Cowles dissolver can be used, and a container resistant to any acid such as a Teflon (registered trademark) coating tank can be used. However, in order to avoid or minimize undesired condensates or precipitates, the mixing speed must be adjusted appropriately to obtain a homogeneous solution. For example, in the case of a propeller stirrer, it is necessary to use a stirring speed of about 1250 to 2000 rpm, spend about 20 minutes, gradually put fumed silica into dilute sulfuric acid, and further stir for 10 minutes. is there. During mixing, the temperature of the mixture is maintained below 40 ° C.

  The non-fluidization of the electrolyte can be performed by a combination of the adsorption characteristics of the glass mat and the low gelation of the electrolyte. In general, the electrolyte is adsorbed to the glass mat separator without any other means. However, the use of a vacuum filling step is significant in that it makes it easier to adsorb the low gelled electrolyte on the separator and electrode plate.

  Due to the low viscosity of the electrolyte in the fully charged state and the presence of hydrophilic silica particles that prevent drying of the separator pores, the lead acid battery with the low gelled electrolyte of the present invention is an efficient charge. With low internal resistance for high energy density, it is possible to obtain long discharges and high current rates or high discharge rates when needed. During discharge, a reversible paste-like gel mass is formed in the pores of the glass mat separator adjacent to the surface of the electrode plate. This gel mass prevents dendrite growth, and the paste-like active material is applied to the electrode plate. The electrode plate is protected by avoiding or delaying the problem of deterioration such as peeling off the surface of the electrode. Therefore, a lead acid battery having a low gelled electrolyte according to the present invention usually has a longer cycle life than expected.

  Moreover, although an electrode plate may be formed in the assembled storage battery, it is desirable to use the electrode plate previously formed. Moreover, although the use of a glass mat separator is preferred, an electrolyte-absorbing separator such as an acid-resistant polymer nonwoven fabric can be used instead. For example, a non-woven fabric based on polyolefin or polyester with appropriate hydrophilic surface treatment is suitable as the absorbent separator.

  In the following, preferred embodiments of the present invention will be described in more detail. However, these examples do not limit the present invention. Still other embodiments can be made without departing from the spirit of the invention as set forth herein. Such embodiments are within the scope of those skilled in the art.

  First, 100 grams of fumed silica, such as Degussa Aerosil 200, and 900 grams of deionized water are mixed to form a uniform mixture. Separately, 9 kilograms of dilute sulfuric acid having a specific gravity of 1.32 is placed in an acid-resistant tank equipped with a propeller stirrer. In a stirrer rotating at 1457 rpm, the fumed silica mixture is gradually added into dilute sulfuric acid over 20 minutes. After the addition is complete, the stirrer is continued and stirred for 10 minutes to obtain a uniform mixture. The viscosity of the resulting low gelled electrolyte is slightly higher than that of dilute sulfuric acid before stirring, and the mixture becomes slightly opaque. The turbidity increases with time but remains free-flowing for an additional three weeks. For the test, a 12V storage battery was assembled at a value of 12 ampere hours (AH) and filled with a low gelled electrolyte. The electrical resistance of the electrolyte between two copper wires separated by a distance of 50 mm was measured. The results are shown in Table 1. A discharge test was conducted using a lead acid storage battery having the low gelled electrolyte of the present invention. Table 2 summarizes the discharge time under various initial discharge rates.

  The second embodiment is performed in the same procedure as the first embodiment. However, an electrolyte was prepared using dilute sulfuric acid having a specific gravity of 1.33, and the stirrer was rotated at 1360 rpm. The general characteristics of the low gelled electrolyte are the same as in Example 1. The electrical resistance of the electrolyte is shown in Table 1, and the results of the initial discharge test are shown in Table 2.

  For comparison, a 12V storage battery with a value of 12 AH was assembled and filled with standard sulfuric acid with a specific gravity of 1.32. The electrical resistance of the electrolyte is shown in Table 1, and the results of the initial discharge test are shown in Table 2.

注：５０ｍｍの距離で隔てられた２本の銅線間で測定された値

Note: Value measured between two copper wires separated by a distance of 50 mm

注１：全ての蓄電池は、１２ＡＨで１２Ｖである。
注２：放電時間は、時・分・秒として記されている。

Note 1: All storage batteries are 12AH and 12V.
Note 2: Discharge time is stated as hours, minutes, and seconds.

  As shown in Table 1, the electrical resistance of the low gelled electrolyte is slightly higher than that of ordinary dilute sulfuric acid, but the amount of increase is slight. In the case of a discharge rate of 2 hours, the effect on the discharge characteristics of the storage battery is Can be ignored. In fact, in general, the 20 hour discharge rate of Example 1-2 shows an unexpected improvement over the standard sulfuric acid storage battery of Comparative Example 1. These data indicate that the present invention is particularly suitable for applications such as electric bicycles and outdoor solar lighting devices that require long discharge times.

  Table 2 also shows the results of fast discharges such as 1C and 3C, and the fast discharges of the present invention are unexpectedly in the same range as standard sulfuric acid batteries, or standard Better than sulfuric acid batteries.

  The improved characteristics of the present invention will be described in more detail. In FIG. 2, the curve of the discharge time between 300 life cycles of Example 2 is shown. Contrary to expectations, it can be clearly seen that the storage battery of the present invention can withstand a longer discharge time than the conventional storage battery of Comparative Example 1 and provides superior characteristics.

  Those skilled in the art will readily appreciate that many variations and modifications of the apparatus and method may be made in accordance with the teachings of the present invention. Accordingly, it is to be understood that the foregoing disclosure is limited only by the metes and bounds of the appended claims.

It is sectional drawing of the conventional lead acid storage battery. It is a figure which shows the comparison curve of the discharge time over 300 discharge cycles of the storage acid battery which has a low gelatinization electrolyte, and the conventional standard storage battery.

Explanation of symbols

10 Lead Acid Battery 12 Positive Plate 14 Negative Plate 16 Separator

Claims (12)

A low gelled electrolyte for a lead acid battery,
Dilute sulfuric acid,
Silica particles substantially in the range of 0.1% to 3% of the weight of the electrolyte,
A low gelled electrolyte, wherein the silica particles are fumed silica particles.   2. The low gelled electrolyte according to claim 1, wherein the dilute sulfuric acid has a specific gravity of 1.28 to 1.34.   The low gelled electrolyte according to claim 1, wherein the silica particles occupy a range of 0.5% to 1% of the weight of the electrolyte. A lead acid battery having a low gelled electrolyte,
(A) a container;
(B) a positive electrode plate and a negative electrode plate provided in the container;
(C) a separator provided between the positive electrode plate and the negative electrode plate in the container;
(D) including a low gelled electrolyte for connecting between the positive electrode plate and the negative electrode plate in the container,
The low gelled electrolyte is:
Having dilute sulfuric acid, and silica particles substantially in the range of 0.1% to 3% of the weight of the electrolyte;
The lead acid storage battery, wherein the silica particles are fumed silica particles.   The lead acid storage battery according to claim 4, wherein the dilute sulfuric acid has a specific gravity of 1.28 to 1.34.   The lead acid storage battery according to claim 4, wherein the silica particles are substantially in the range of 0.5% to 1% of the weight of the electrolyte.   The lead acid storage battery according to claim 4, wherein the lead acid storage battery is a control valve type.   The lead acid storage battery according to claim 4, wherein the separator can adsorb an electrolyte.   The lead acid storage battery according to claim 8, wherein the separator is a glass mat.   The lead acid storage battery according to claim 8, wherein the separator is a polymer nonwoven fabric. The lead acid storage battery according to claim 8, wherein the separator is made of polyolefin.   The lead acid storage battery according to claim 8, wherein the separator is a polyester-based nonwoven fabric.

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