Field of the invention

The invention relates to a method for preparation of positive and negative pastes for lead-acid battery cells and batteries under the influence of a modulated low-energy magnetic field and it will be applicable in their production.

Background of the invention

Nowadays the lead-acid battery cells and batteries belong to some of the most popular chemical sources of electrical energy. The price of the lead- acid batteries, the wide accessibility of the basic raw materials and the high- level automation of the production processes determine the constantly broadening fields of their application. As is well known, the lead-acid batteries are generally divided into three major types: starter batteries, traction batteries and stationary batteries. The operational characteristics of the various types of lead-acid battery cells and batteries depend on many factors. One of the most important factors, determining the properties of the lead-acid batteries, is the preparation of the positive and the negative pastes for their production.

The main chemical processes, which take place during the paste preparation, are described by Barnes and Mathieson. The authors have indicated in their work, that the main paste components were lead (III) oxysulfate, lead oxide and metallic lead, which was included in the original lead oxides. Ill The pastes are prepared though mixing of lead-oxide powder with sulfuric acid solution, whereby lead oxysulfates are formed. A non-reacted PbO, oxyhydrates and particles of a non-oxidized metallic lead also remain in the paste.

The basic raw materials for the preparation of positive and negative pastes for lead-acid batteries are the following:

a) lead-oxide powder;

b) ¾0;

c) H2SO4 in concentrations of 1.20 - 1.40 g/cm ;

d) additives:

• for the negative paste:

- expander (lignosulfonate), BaS0 and carbon black;

- inhibitors;

• for the positive paste:

- polymer fibers;

Generally, the processes which take place in order to obtain the two main types of basic lead oxysulfates 3PbO.PbS04.H20 and 4PbO.PbS04 are described through the following equations:

5PbO + H ₂ S0 ₄ *-» 4Pb0.PbS0 ₄ + ¾0

4(Pb0.PbS0 ₄ ) + H ₂ S0 ₄ + 4¾0 <→ 5(3PbO.PbS0 ₄ .¾0)

2(3PbO.PbS0 ₄ .¾0) + H ₂ S0 ₄ → 4(4PbO.PbS0 ₄ ) + 4H ₂ 0

4Pb0 + H ₂ S0 ₄ → 3Pb0.PbS0 ₄ .¾0

tet.-PbO <→ o.-PbO The chemical character of the lead sulfates, which are used for the paste preparation, is of major importance for the electrochemical characteristics of the lead-acid batteries manufactured thereof. These batteries, depending on the application which they are designated for, are manufactured from especially prepared positive and negative pastes with different in quantity and parameters basic raw materials. The achievement of long useful life, high reliability and high energy return factor of the lead-acid accumulators depends to a great extent on the methods for paste preparation for the production of the positive and the negative electrodes therein. As a result of this, high-grade pastes can be obtained as a function of the conditions and the basic raw materials, which they are manufactured from. Namely: quick hardening of the paste after its applying on the conductive electrode grids, tight adhesion of the paste to the grid, providing a good electric contact, and also strength and porosity of the electrodes, ensuring the reversibility of the electrochemical processes upon lead-acid battery cycling. It is remarkable, that the methods for preparation of pastes determine their phase composition, which is expressed as the content and the quality and quantity ratios of the basic (III) and (IV) lead oxy sulfates.

When lead-acid batteries with high initial energy parameters are produced, it is necessary the pastes to be prepared under such conditions and from such basic raw materials, so that they comprise mainly lead (III) oxysulfates. When the lead-acid batteries shall have a steady-state morphology of the crystal electrode structure, in that case it is required the pastes to be prepared with increased content of lead (IV) oxysulfates. In order to reduce the disadvantages during operation of the lead-acid batteries and to improve their electrical parameters and their operational efficiency, the preparation of high-quality positive and negative pastes for them is required.

Various technologies and methods for preparation of positive and negative pastes for the lead-acid battery production are known, which are aimed at the enhancement of the operational parameters of the lead-acid battery cells and batteries, manufactured thereof. However, all of them are related either to a variation of the chemical composition of the basic raw materials, or to an addition of various additives to the pastes for the purpose of their modification in accordance with the function of the particular lead-acid battery types.

For example, it is fact that the application of polymer fibers in quantity up to 6.5 % of the PbO weight improves the mechanical strength of the paste. Ill According to another solution is known, that the addition of small quantities of copper oxide, antimony oxide and tin oxide increases the initial capacity of the lead-acid batteries. 13/

In accordance with a further solution, various carbon and silicon materials are proposed to be added into the negative pastes, in order to inhibit the sulfatization of the negative electrodes during the lead-acid battery operation. 141 Also methods are known, which determine another direction, where the proposals concern the manufacture of pastes for lead-acid batteries with a preliminary preparation of the basic raw materials.

A solution is known, where the initial lead oxides are suggested to be processed beforehand with a hydrogen peroxide solution and thereafter the pastes for lead-acid batteries to be prepared from this material./5/

According to a further solution, blowing of the positive fresh coated plates is suggested to be done with ozone for the purpose of more effective oxidation of the non-oxidized metallic lead./6/

In accordance with a next solution, the paste is recommended to be diluted with water to a suspension, which ensures better homogenization, and then the water has to be drained off until such consistency is obtained, which allows the paste to be applied on the plate grids. Ill

Disclosure of the invention

The present patent on invention proposes a new solution to obtain positive and negative pastes with improved quality features, using a method of influence by means of a modulated low-energy magnetic field during the preparation of positive and negative pastes for the production of various lead-acid battery types.

According to the invention, the method for preparation of positive and negative pastes for lead-acid battery cells and batteries under the influence of a modulated low-energy magnetic field takes place by means of the following operations in their sequence:

- evaluation of the modulation energy depending on the paste type and the paste quantity, as well as depending on the lead-acid battery type, in an operating frequency range from Γ ¹⁰ Ηζ to l ²⁰ Hz;

- creation of a specific software to generate, to file and to display the evaluated parameters of the modulated signal, which will be used during the preparation of various positive or negative paste types, in a frequency range from r ¹⁰ Hz to l ²⁰ Hz;

- realization of a direct influence through the modulated low-energy magnetic field on the pastes at the facilities, where the respective production process takes place.

The method, proposed according to the present patent, offers the possibility of effective performance of the chemical, crystallization and re- crystallization processes in the manufacture of positive and negative pastes for the production of lead-acid batteries and cells with enhanced power and operational parameters.

The advantages of the indicated method are as follows :

• An increase by 20 % and more is achieved with regard to the content and the quality of the three or four oxysulfates required in the pastes, depending on the type of the lead-acid batteries, which the respective pastes are destined for. • The time for preparation of the positive and negative pastes is shortened and the energy consumption for their production is reduced by more than 40 %.

• The morphology and the phase composition of the positive and negative pastes are improved, no matter what kind of additives are used for their preparation.

• Preconditions for the effective performance of the chemical, crystallization and re-crystallization processes in the preparation of the pastes are established, regardless of the type of the mixers and the machines, which the pastes are manufactured in.

Explanation of the attached figures

The method for preparation of positive and negative pastes for the production of lead-acid battery cells and batteries through the realization of influence by means of a modulated low-energy magnetic field is explained, but not limited to, by the attached Figure 1.

Exemplary embodiment of the invention

According to the attached Fig. 1 the method for preparation of positive and negative pastes for the production of lead-acid battery cells and batteries through the exercise of influence by means of a modulated low-energy magnetic field takes place through a control module 1 with specialized software, which is connected to a source of a modulated magnetic field 2 and an equipment 3, wherein the pastes are prepared. The control device 1 is destined to create in a timed controlled manner a modulatmg sinusoidal signal with preset, depending on the paste type and the paste quantity, specific parameters in the frequency range from l ^"lft Hz to l ²⁰ Hz.

The source of the modulated low-energy magnetic field 2, and also the equipment 3 are subject to the type of manufactured pastes.

In accordance with the proposed method, the first step is to evaluate the modulation energy, depending on the paste type and the paste quantity, in a frequency range from Γ ¹⁰ Ηζ to l ²⁰ Hz.

After evaluation of the modulation energy, the creation of a specific software is initiated to generate, to file and to display the evaluated parameters of the modulated signal in a frequency range from Γ ¹⁰ Ηζ to l ²⁰ Hz. This signal will impact on the respective paste, which is prepared in the paste production equipment.

A direct influence follows by means of a modulated low-energy magnetic field on the various types of positive or negative pastes, which are prepared at that moment.

The proposed method for preparation of positive and negative pastes for lead-acid battery cells and batteries under the influence of a modulated low- energy magnetic field is disclosed, but not limited or exhausted, by the following examples, Example 1

The preparation of a paste for positive electrodes takes place according to the following recipe:

- 1000 g PbO, 76 % oxidation level;

- 110 ml distilled ¾0;

- 75ml H ₂ S0 with a density 1.40 g/cm ³ .

A mixer consisting of a plastic cylindrical vessel and mechanical stirrers, made of stainless steel, is used. The source of a modulated magnetic field is mounted fixed on the vessel side. First of all, the lead oxide powder is put into the vessel and the control device, which initiates the source of the modulated magnetic field, is switched on. The distilled water is added and the stirring of the compound is switched on for three minutes. Subsequently, the sulfuric acid solution is added in portions of 20 ml, and finally in the twentieth minute after the beginning of stirring, the last 30 ml sulfuric acid solution is added. Stirring of the paste, after the beginning of addition of sulfuric acid solution, continues 30 minutes in all, while the paste temperature is continuously monitored not to exceed 40 °C. Over the entire time of preparation of the positive paste, an influence by means of a modulated magnetic field in the frequency range from l ^_m Hz to l ²⁰ Hz is applied.

Example 2

Preparation of a paste for negative electrodes. The negative paste comprises an additional quantity of carbon material for the purpose of manufacturing negative electrodes with increased electric conductivity and the possibility of reduced sulfatization of the negative electrodes upon lead-acid battery cycling. This paste is prepared in accordance with the following recipe:

- 1000 g PbO, 76 % oxidation level - 4 g BaS0 ₄ ;

- 2 g Vanisperse;

- 20 g carbon material with an index TDA-AC, produced by the company Cabot Corporation, USA;

- 125 ml distilled ¾0;

- 76 ml ¾S0 ₄ with a density 1.40 g/cm ³ .

A mixer consisting of a plastic cylindrical vessel and mechanical stirrers, made of stainless steel, is used. As in example 1, the source of a modulated magnetic field is mounted fixed on the vessel side. Upon preparation of the paste for the negative electrodes of the lead-acid batteries, first of all a lead oxide powder is put into the vessel of the mixer and a source of a modulated magnetic field is switched on. Subsequently BaS04, Vanisperse and carbon material TDA-AC is added and the stirring of the dry mixture is switched on for two minutes. After the compound is mixed in dry condition, the required quantity of distilled water is added and the mixing continues for another three minutes. Subsequently, the sulfuric acid solution is added in portions of 20 ml, and finally in the twentieth minute after the beginning of stirring, the last 35 ml sulfuric acid solution is added. Stirring of the paste, after the beginning of addition of sulfuric acid solution, continues 30 minutes in all, while the paste temperature is continuously monitored not to exceed 40 °C. Over the entire time of preparation of this negative kind of paste, an influence by means of a modulated magnetic field in the frequency range from Γ ¹⁰ Ηζ to l ²⁰ Hz is applied.

Literature:

1. Barnes S.A., Mathieson R.T. - Batteries, vol. 2,

Perg. Press, 1965, p. 41- 45.

2. US 4323470 A

3. US 5352549 A

4. US 20120115031

5. US 4909955 A

6. US 4656706 A

7. US 5290359