WO2012121627A1

WO2012121627A1 - Paste for the negative electrode of a lead-acid battery and method for manufacturing said paste

Info

Publication number: WO2012121627A1
Application number: PCT/RU2012/000158
Authority: WO
Inventors: Ольга Геннадьевна НИКИТИНА; Игорь Леонидович КОПТЕЛОВ; Андрей Анатольевич УСКОВ
Original assignee: Общеcтво С Ограниченной Отвественностью "Новогородская Аккумуляторная Компания"
Priority date: 2011-03-05
Filing date: 2012-03-02
Publication date: 2012-09-13
Also published as: RU2454756C1

Abstract

The inventions relate to electrical engineering, and specifically to paste compositions for the negative electrodes of stationary lead-acid batteries and to the technology for manufacturing said compositions. A paste for the negative electrode of a lead-acid battery, the paste comprising lead powder, H₂SO₄, an expander, including BaSO₄, sodium lignosulphonate, and also water, additionally comprises gas black, with the following ratio of components: 8-10% by mass of H₂SO₄; 0.3-0.5% by mass of BaSO₄; 0.1-0.2% by mass of sodium lignosulphonate; 0.2-0.3% by mass of gas black; 7-8% by mass of water; the remainder being lead powder, wherein the particle size of BaSО₄ does not exceed 10 nm; the paste may additionally comprise polyvinyl chloride fibre in an amount of 0.03-0.06% by mass. In a method for manufacturing the paste for the negative electrode of a lead-acid battery by mixing lead powder, H₂SO₄ and an expander, first of all the lead powder and expander are mixed for 8-15 min, then water is added, the mixture is stirred for 8-15 min, after which H₂SO₄ is added at a rate of 0.7-0.8 l/min with stirring, wherein the temperature of the mixture is maintained within the range of 30-70°С. The premature loss of electrical capacitance of the battery is prevented and the service life of said battery extended; the formation of monobasic lead sulphate is reduced and, accordingly, the loss of capacitance of the battery is prevented.

Description

Paste for a negative electrode of a lead-acid battery and method for its manufacture

Technical field

The invention relates to electrical engineering, in particular to the compositions of pastes for negative electrodes of stationary lead-acid batteries and the technology for their manufacture.

State of the art

Known paste for the negative electrode of a lead battery, consisting of lead powder, sulfuric acid and an expander containing a barium component based on tanning agent; in order to increase and stabilize the capacitance in the starter discharge modes, this component was taken in the form of barium salt of a synthetic tanning agent, SU 359712. A tanning agent 20 Ν 4 or BNF is used as a tanning agent. The expander is introduced in an amount of 0.1 to 3%, calculated on the dry matter to the weight of the lead powder. The content of sulfuric acid monohydrate reaches 36-50%. The disadvantage of this technical solution is the low porosity of the resulting active mass due to the use of a barium component based on a tanning agent, which is a gummy thick substance, as an expander; upon drying, the porosity and mechanical strength of the active mass are insufficient. The resulting active mass is solid, but very fragile. Paste according to SU 395712 can be used for electrodes of small thickness, used, for example, in car batteries.

Known paste for the negative electrode of a lead-acid battery containing lead powder, sulfuric acid, an expander, including barium sulfate and sodium lignosulfonate, as well as water; Sodium lignosulfonate is 0.1-0.3% by weight of lead powder, SU 199941.

Due to the presence of an expander in the form of barium sulfate and sodium lignosulfonate, the porosity of the active mass increases.

This technical solution was made as a prototype of the claimed substance.

A surfactant (sodium lignosulfonate) does not sufficiently block lead sulfate crystals, which leads to their growth and irreversible sulfation of the active mass of the electrode. This leads to a significant loss of battery capacity and shorten its service life. It should also be noted that in the manufacture of the known paste, monobasic lead sulfate (PbO x PbS0 ₄ ) is formed to a large extent. This leads to a decrease in volume, hardening, decrease in porosity and cracking of the active mass of the electrode, loss electrical capacity of the battery and reducing its service life.

In addition, when using the prototype paste, the recovery of lead sulfate during the battery charge is not uniform in the volume of the electrode, which prevents the effective recovery of lead sulfate into sponge lead during battery charging and reduces its capacity.

As a prototype of the invention in terms of the method, a technical solution was made according to the book: M. A. Dasoyan “Chemical Current Sources”, Energia Publishing House, L, 1969, p. 211 (a copy of the link is attached).

According to the specified source, lead powder is first poured into the mixer and sulfuric acid is then poured immediately after it, and then separately water is added. In the manufacture of paste for the negative electrode, an expander is introduced simultaneously with the lead powder.

The disadvantage of this method is the formation of a large amount of monobasic lead sulfate due to the fact that H2SO4 is immediately introduced into the lead powder, which leads to rapid irreversible sulfation of the active mass and, consequently, loss of battery capacity.

Disclosure of inventions The objective of the invention in terms of substance is to prevent premature loss of electrical capacity of the battery and extend its service life. The objective of the invention in terms of a method of manufacturing a paste for a negative electrode of a lead-acid battery is to reduce the formation of monobasic lead sulfate and, accordingly, to prevent loss of battery capacity.

According to the invention, in terms of the substance in the paste for the negative electrode of a lead-acid battery containing lead powder, H2SO4, an expander comprising BaS0 ₄ and sodium lignosulfonate, as well as water, the expander additionally contains gas soot, in the following ratio, wt.%:

H ₂ S0 ₄ 8 - 10

BaS0 ₄ 0.3 - 0.5

sodium lignosulfonate 0.1 - 0.2

gas soot 0.2 - 0.3

water 7 - 8

lead powder rest,

while the particle size of BaS0 ₄ does not exceed 10 nm; the paste may further comprise polyvinyl chloride fiber in an amount of 0.03-0.06 mass%.

The paste may additionally contain polyvinyl chloride fiber, in this example, 3 to 4 mm long, in an amount of 0.03 to 0.06 mass%, which provides an increase in the mechanical strength of the paste.

According to the invention, in a method for manufacturing a paste for a negative electrode of a lead-acid battery by mixing a lead powder, H ₂ S0 ₄ and an expander, the lead powder and expander are first mixed 8-15 minutes, then add water, mix the mixture for 8-15 minutes, then add H ₂ S0 ₄ at a rate of 0.7-0.8 l / min with stirring, while maintaining the temperature of the mixture within 30-70 ° C.

The applicant has not identified sources containing information about technical solutions identical to the present inventions, which allows us to conclude that they meet the criterion of "Novelty" ("N").

The applicant has not found any sources of information containing information on the effect of the declared distinctive features on the technical result achieved as a result of their implementation, consisting in preventing premature loss of battery electric capacity and extending its service life, which, according to the applicant, indicates the conformity of these technical solutions the criterion of "inventive step" ("IS").

BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention is illustrated by a detailed description of examples of their implementation without reference to the drawings.

BEST MODE FOR CARRYING OUT THE INVENTIONS The paste for the negative electrode of a lead-acid battery contains lead powder in the form of lead acid. When the content of sulfuric acid is less than 8 wt.%, Conditions arise that contribute to the formation of monobasic sulfate lead, with a sulfuric acid content of more than 10 wt.%, the conditions for the formation of tribasic lead sulfate are worsened. When the sulfuric acid content is in the range of 8-10 wt.%, The primary formation of tribasic lead sulfate occurs, which reduces the irreversible sulfation of the active mass of the electrode. When the content of BaS0 _{4 is} less than 0.3 wt.%, The centers of crystallization of spongy lead decrease during battery charge and pronounced irreversible sulfation of the electrode occurs, when the content of BaS0 _{4 is} more than 0.5 wt.%, Crystals of tribasic lead sulfate are blocked and its reduction rate decreases. The use of BaS0 ₄ particles with a size of no more than 10 nm can significantly increase the isomorphism of the crystallization process and the area of the active surface of the electrode. This ensures uniform recovery in volume of the electrode of tribasic lead sulfate to a finely dispersed spongy phase of metallic lead.

When the content of sodium lignosulfonate is less than 0.1 wt.%, Sufficient adsorption of anions on the surface of spongy lead is not ensured, which leads to its incomplete oxidation to lead sulfate and the conversion of unoxidized lead to large crystalline monobasic sulfate; Thus, irreversible sulfation of the active mass of the electrode occurs with loss of capacity and reduced battery life.

If the content of sodium lignosulfonate is more than 0.2 wt.%, Adsorption of anions on sulfates occurs. As a result of this process, the resulting large crystalline lead sulfate closes the pores. In addition, the content of sodium lignosulfonate in excess of 0.2 wt.% Promotes the appearance of shrinkage of the active mass.

Gas soot is introduced in this composition to increase the porosity of the active mass, as well as to control the rate of delivery of surfactants to the crystallization centers of metallic lead. It also contributes to a certain decrease in the final charging voltage of the battery, taking over an excess of surfactants.

When the carbon black content is less than 0.2 wt.%, There is insufficient porosity of the active mass, its volume decreases; in addition, the rate of delivery of surfactants to the crystallization centers of metallic lead is slowed down.

If the carbon black content is more than 0.3 wt.%, The porosity of the active mass increases excessively, which leads to a strong increase in its volume and an unacceptable decrease in mechanical strength; in both cases, the electric capacitance rapidly decreases and the service life of the plates decreases.

Water, in a specific example, deionized, is added in order to create the desired consistency of the paste, as well as to maintain the pH of the paste within the required limits.

If the water content is less than 7 wt.%, The pH of the paste will be insufficient for the conversion of lead oxide to tribasic lead sulfate; in addition, an insufficient amount of water contributes to the rapid hardening of the paste and, therefore, the paste becomes unsuitable for spreading on the down conductor. When the water content is more than 8 wt.%, The pH increases, it becomes possible to form PbOPbS0 ₄ or PbS0 ₄ . There is also an excessive increase in the porosity of the paste, which leads to an increase in the capacity of the battery, but significantly reduces the service life of the active mass.

In the manufacture of the paste, the lead powder and the expander are first mixed, the mixture is stirred for 8-15 minutes to achieve a better distribution of the expander in the lead powder. After that, water is added. When water is added, the mixture is well mixed for 8-15 minutes so that the lead is oxidized before the introduction of H ₂ S0 ₄ and an alkaline medium forms: PbOn-OH. Only after that, sulfuric acid is added to the alkaline medium at a rate of 0.7 - 0.8 l / min. As sulfuric acid is neutralized during the mixing of the paste, tribasic lead sulfate is formed. The indicated rate of introduction of H ₂ S0 ₄ corresponds to the reaction rate of the solid-state transition PbOPbS0 ₄ -> 3PbOPbS0 ₄ H ₂ 0 with increasing paste pH, which reduces the formation of monobasic lead sulfate and prevents the loss of battery capacity.

If the rate of introduction of acid is less than 0.7 l / min., Then the pH will change very slowly and unevenly, as a result of which conditions will be created for the formation of monobasic lead sulfate in certain areas of the paste.

If the rate of introduction of acid is less than 0.8 l / min., Then a significant part or all of the lead oxide will be converted to PbS0 ₄ .

The temperature of the mixture in the manufacture of paste is maintained within the range of 30 - 70 ° C. The proposed paste manufacturing technology can significantly reduce the formation of monobasic lead sulfate, which helps to prevent loss of battery capacity. Industrial applicability

For the implementation of the inventions, well-known materials and equipment are used, which determines, according to the applicant, the inventions comply with the criterion of “Industrial Applicability” (“IA”).

Claims

Claim

1. Paste for the negative electrode of a lead-acid battery containing lead powder, H2SO4, an extender comprising BaS0 ₄ , sodium lignosulfonate, and also water, characterized in that it additionally contains carbon black, in the following ratio, wt%:

H ₂ S0 ₄ 8-10

BaS0 ₄ 0.3 - 0.5

sodium lignosulfonate 0.1-0.2

gas soot 0.2 - 0.3

water 7-8

lead powder rest,

while the particle size of BaS0 ₄ does not exceed 10 nm.

2. The paste according to claim 1 of the formula, characterized in that it further comprises polyvinyl chloride fiber in an amount of 0.03-0.06 mass%.

3. A method of manufacturing a paste for a negative electrode of a lead-acid battery by mixing lead powder, H ₂ S0 and an expander, characterized in that the lead powder and expander are first mixed for 8-15 minutes, then water is added, the mixture is mixed for 8- 15 minutes, after which H ₂ S0 _{4 is} added at a rate of 0.7-0.8 l / min with stirring, while maintaining the temperature of the mixture in the range of 30-70 ° C.