WO2008032337A1

WO2008032337A1 - Lead acid battery

Info

Publication number: WO2008032337A1
Application number: PCT/IN2007/000397
Authority: WO
Inventors: Ajoy Datta
Original assignee: Luminous Power Technologies Pvt Ltd
Priority date: 2006-09-11
Filing date: 2007-09-10
Publication date: 2008-03-20

Abstract

Plates for a lead acid battery and cell assemblies comprising such plates is described. In another aspect, the subject matter describes, a lead acid battery comprising such cell assemblies.

Description

LEAD ACID BATTERY

FIELD OF THE INVENTION

This invention in general relates to a lead acid battery and in particular to the plates of a lead acid battery.

BACKGROUND

A lead-acid battery is a secondary electrochemical device that stores energy and makes it available in an electrical form. Lead acid batteries are the most widely used secondary batteries, extensively employed in applications like automobiles. The lead acid battery may comprise of several cells connected in parallel or series.

The basic construction of the cell comprises a positive electrode, a negative electrode, and an electrolyte which is dilute sulphuric acid. The positive electrode and the negative electrode are also referred to as the positive and negative plates respectively. A paste generally comprising lead oxide, lead sulphate, water and certain other additives, taken in a fixed proportion, is applied to a grid to form a plate. Electrical connections are provided between grids acting as positive and negative plates.

In conventional battery designs, the use of single inter cell electrical connection between adjacent cells restricts cell-to-cell current flow. Single inter cell electrical connections contribute to higher internal resistance of a battery and have an adverse impact on high power discharge performance and rapid recharge capabilities of the battery. Further, single inter cell connections are prone to mechanical failure, affecting battery robustness and operational safety. Another fundamental limitation of conventional single inter cell connections is non uniform current density over the plate geometry. Due to the non uniform current distribution, the portion of the grid closest to the connector corrodes more compared to the portions further away from the connector.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.

In an embodiment of the subject matter described herein, a plate for a lead acid battery is described. The plate comprises a grid, a positive paste and a negative paste. The grid comprises a first section, a second section, a third section, a fourth section and a fifth section. The sections are such that the second section is adjacent to the first section, the third section is adjacent to the second section, the fourth section is adjacent to the third section and the fifth section is adjacent to the fourth section. The first, third, and fifth section have a substantially same first dimension and the second and the fourth section have a substantially same second dimension. The first section is pasted with the positive paste while the third and the fifth sections are pasted with the negative paste. The second section is folded such that the first section and the third section are substantially parallel to each other and substantially perpendicular to the second section. The first and the third sections are on same side of said second section. The fourth section is folded such that the third section and the fifth section are substantially parallel to each other as well as substantially perpendicular to the fourth section. The third section and said fifth section are on the same side of said fourth section and the third section is between the first section and the fifth section. In another embodiment, a cell assembly for a lead acid battery is described. The cell assembly comprises a positive terminal plate having a grid of a first predetermined dimension with a positive paste pasted onto the grid and a negative terminal plate comprising a grid and a negative paste. The grid of the negative terminal plate comprises a first section, a second section and a third section such that the second section is adjacent to the first section and the third section is adjacent to the second section. The first and third sections have the first predetermined dimension and the second section has a second predetermined dimension. The first and third sections are pasted with the negative paste. The second section is folded such that the first section and the third section are substantially parallel to each other and substantially perpendicular to the second section and are on the same side of the second section. The cell assembly further comprises intermediate plates wherein each intermediate plate is a plate of the previous embodiments, one or more separators and one or more insulating plates.

The cell assembly is formed of a plurality of cells namely a first cell, a last cell and one or more intermediate cells. The first cell comprises the positive terminal plate, one or more separators and the negative sections of the intermediate plate. The positive terminal plate is placed between the negative sections and one separator is placed on each side of the positive terminal plate in contact with said negative sections. The last cell comprises the positive section of the intermediate plate, the negative terminal plate and one or more separators such that the positive section is placed between the negative terminal plate. A separator is placed on each side of the positive section in contact with the negative terminal plate. A purality of intermediate cell is present between the first cell and the last cell. Each intermediate cells comprises intermediate plates and separators placed such that the positive section of one intermediate plate is placed between the two negative sections of another intermediate plate. A said separator is placed on each side of the positive section in contact with the negative sections. Insulating plates are placed between adjacent cells and the first cell is at one end of the intermediate cells and the last cell is at other end of said intermediate cells.

In yet another embodiment a lead acid battery is described. The lead acid battery assembly comprises a positive terminal a negative terminal and one or more lead acid battery assembly of the previous embodiment. The positive terminal plate of the first cell is electrically connected to a positive terminal of the battery and the negative terminal plate of the last plate is electrically connected to a negative terminal of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 provides an illustration of a grid 100.

Fig 2 provides an illustration of a plate for lead acid battery comprising the grid of Fig. 1.

Fig. 3 provides an illustration of a positive terminal plate.

Fig. 4 provides an illustration of a negative terminal plate.

Fig. 5 provides an illustration of a cell assembly for a lead acid battery comprising a plurality of plates of Figs. 2, 3 and 4.

Fig. 6 provides an illustration of a lead acid battery comprising one or more cell assembly of Fig.5.

Fig. 6A provides an illustration a top view of a lead acid battery comprising one or more cell assembly of Fig.5. DETAILED DESCRD7TION

The subject matter describes, in one aspect, plates for a lead acid battery and a cell assembly formed by a plurality of such plates. In another aspect the subject matter describes a lead acid battery comprising such cell assemblies.

Aspects of the lead acid battery described herein can be implemented in any number of different environments, and/or configurations that will be obvious to a person skilled in the art. Different embodiments of the battery are herein described in the context of the following exemplary method(s) only as examples and are not limiting to the scope of the described subject matter.

Example 1

Fig. 1 provides an illustration of a grid 100.

The figure illustrates a grid 100 comprising a first section 102, a second section 104 a third section 106,a fourth section 108 and a fifth section 110. The sections are placed such that the second section 104 is adjacent to the first section 102, the third section 106 is adjacent to the second section 104, the fourth sectionl08 is adjacent to the third section 106 and the fifth section 110 is adjacent to said fourth section 108. The first section 102, the third section 106, and the fifth section 110 have substantially a same first dimension while the second section 104 and the fourth section 108 have substantially a same second dimension.

The grid 100 is a wire mesh made of metallic material or alloy. The grid 100 is typically made of metallic lead or a lead-based alloy. The grid 100 is made by conventional techniques such as direct casting, stamping, forging or by mechanical working.

Example 2 Fig 2 provides an illustration of a plate 200 for lead acid battery comprising the grid of Fig. 1.

The plate 200 comprises the grid 100 of Example 1, a positive paste and a negative paste.

The first section 102 of grid 100 is pasted with the positive paste while the third section 106 and the fifth section 110 are pasted with the negative paste. The second section 104 is folded such that the first section 102 and the third section 106 are substantially parallel to each other and substantially perpendicular to the second section 104. The folding of the first section 102 and the third section 106 is such that they are on same side of the second section 104. Similarly, the fourth section 108 is folded such that the third section 106 and the fifth section 110 are substantially parallel to each other and substantially perpendicular to the fourth section 108. The third section

106 and the fifth section 110 are on the same side of the fourth section 108 with the third section

106 lying in between the first section 102 and the fifth section 110.

Example 3

Fig. 3 provides an illustration of a positive terminal plate 300.

The positive terminal plate 300 comprises a grid 302 and a positive paste pasted onto the grid 302. The grid 302 has a predetermined dimension.

Example 4

Fig. 4 provides an illustration of a negative terminal plate 400.

The negative terminal plate 400 comprises a grid 402 and a negative paste. The grid 402 comprises a first section 404, a second section 406, and a third section 408. The second section 406 is adjacent to the first section 404 and the third section 408 is adjacent to the second section 406. The first section 404 and the third sections 408 have a substantially same first predetermined dimension while second section 406 has a second predetermined dimension. The first section 404 and third section 408 are pasted with the negative paste. The second section 406 is folded such that the first section 404 and the third section 408 are substantially parallel to each other and substantially perpendicular to the second section 406 and are on the same side of the second section 406.

Example 5

Fig. 5 provides an illustration of a cell assembly 500 for a lead acid battery comprising a plurality of plates of Fig.2.

The figure illustrates a cell assembly 500 for a lead acid battery. The cell assembly 500 comprises a positive terminal plate 300 as illustrated in Example 3, a negative terminal plate 400 as illustrated in Example 4 and one or more intermediate plates. The intermediate plates are plates 200 of Example 2.

The cell assembly 500 comprises a first cell 502, a last cell 504 and one or more intermediate cells 506. The first cell 502 comprises the positive terminal plate 300, the negative sections of an intermediate plate 200 such that the positive terminal plate 300 is placed between the negative sections. A separator is placed on each side of the positive terminal plate 300 in contact with said negative sections.The last cell 504 comprises the positive section of an intermediate plate 200 and the negative terminal plate 400. The positive section is placed between the negative terminal plate 400 and a separator is placed on each side of the positive section in contact with said negative terminal plate 400. Each of the intermediate cells 506 comprises intermediate plates 200 and separators such that the positive section of a intermediate plate 200 is placed between the two negative sections of another intermediate plate 200. A separator is placed on each side of the positive section in contact with the negative sections. Insulating plates 508 are placed between adjacent cells. The first cell 502 is at one end of the intermediate cells 506 and the last cell 504 is at other end of the intermediate cells 506.

The cell assembly 500 further comprises two compression plates 510 and 512. The cell assembly 500 is compressed to a predetermined pressure and the two compression plates 510 and 512 are locked in place. The cell assembly 500 can be compressed using techniques known to the prior art. The compressed cell assembly 500 can be locked in place using welded or bolted ties or using any other locking arrangement described in the prior art.

Example 6

The figure illustrates a lead acid battery 600 comprising a container 602 having a positive terminal 604 and a negative terminal 606 and one or more cell assembly 500 of the previous embodiment. The cell assemblies 500 are arranged such that the positive terminal plate 300 of said first cell 502 is electrically connected to the positive terminal 604 and the negative terminal plate

400 of the last cell 504 is electrically connected to the negative terminal 606.

Fig. 6A provides an illustration a top view of a lead acid battery comprising one or more cell assembly of Fig.5.

The figure illustrates a lead acid battery 600 of Fig.6 two cell assemblies 500. The two cell assemblies 500 are separated by container partitions 610 which are made of the same material as the container 602 or any other acid resistant, acid impervious and non conductive material. While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

I / We claim:

1. A plate for a lead acid battery comprising:

a grid;

a positive paste; and

a negative paste;

wherein the grid comprises:

a first section;

a second section;

a third section;

a fourth section; and

a fifth section such that said second section is adjacent to said first section, said third section is adjacent to said second section, said fourth section is adjacent to said third section and said fifth section is adjacent to said fourth section and said first, said third, and said fifth section have substantially the same said first dimension and said second and said fourth section have substantially the same said second dimension and wherein said first section is pasted with said positive paste, said third and said fifth section are pasted with said negative paste and said second section is folded such that said first section and said third section are substantially parallel to each other and substantially perpendicular to said second section and said first and said third section are on same side of said second section, said fourth section is folded such that said third section and said fifth section are substantially parallel to each other and substantially perpendicular to said fourth section and said third section and said fifth section are on the same side of said fourth section and said third section is between said first section and said fifth section.

2. The plate of claim 1, wherein said grid is a wire mesh.

3. The plate of claim 1 , wherein said grid is made of a metallic material or alloy.

4. A cell assembly for a lead acid battery comprising:

a positive terminal plate comprising:

a grid; and

a positive paste pasted onto the grid wherein said grid has a first predetermined dimension

a negative terminal plate comprising

a grid; and

a negative paste wherein said grid comprises:

a first section;

a second section; and

a third section such that said second section is adjacent to said first section and said third section is adjacent to said second section and said first and third sections have substantially said first predetermined dimension and said second section has a second predetermined dimension and wherein said first and third sections are pasted with the negative paste said second section is folded such that said first section and said third section are substantially parallel to each other and substantially perpendicular to said second section and are on the same side of said second section; and

intermediate plates wherein each intermediate plate comprises:

a grid;

a positive paste; and

a negative paste, wherein the grid comprises:

a first section;

a second section;

a third section; a fourth section; and

a fifth section such that said second section is adjacent to said first section, said third section is adjacent to said second section, said fourth section is adjacent to said third section and said fifth section is adjacent to said fourth section and said first, said third, and said fifth section have substantially the same said first predetermined dimension and said second and said fourth section have substantially the same said second predetermined dimension and said first section is pasted with said positive paste to form positive section, said third and said fifth section are pasted with said negative paste to form negative sections and wherein said second section is folded such that said first section and said third section are substantially parallel to each other and substantially perpendicular to said second section and said first and said third section are on same side of said second section, said fourth section is folded such that said third section and said fifth section are substantially parallel to each other and substantially perpendicular to said fourth section and said third section and said fifth section are on the same side of said fourth section and said third section is between said first section and said fifth section;

one or more separators;

one or more insulating plates;

a first cell comprising:

said positive terminal plate;

said separators; and

said negative sections of said intermediate plate such that said positive terminal plate is placed between said negative sections and one said separator is placed on each side of said positive terminal plate in contact with said negative sections

a last cell comprising: said positive section of said intermediate plate;

said negative terminal plate; and

said separators such that said positive section is placed between said negative terminal plate and one said separator is placed on each side of said positive section in contact with said negative terminal plate; and

one or more intermediate cells, wherein each cell comprises:

said intermediate plates; and

said separators such that said positive section of one intermediate plate is placed between said two negative sections of another intermediate plate, one said separator is placed on each side of said positive section in contact with said negative sections wherein the insulating plates are placed between adjacent cells and said first cell is at one end of said intermediate cells and said last cell is at other end of said intermediate cells.

5. The cell assembly of claim 4, wherein said grids are made of wire mesh.

6. The cell assembly of claim 5, wherein said grids are made of a metallic material or alloy.

7. The cell assembly for a lead acid battery of claim 4, 5, or 6 further comprising two compression plates.

8. A lead acid battery comprising one or more cell assembly of claims 4, 5, 6 or 7.

9. A lead acid battery comprising:

a container comprising:

a positive terminal; and

a negative terminal; and

one or more cell assembly of claims 4, 5, 6 or 7 such that said positive terminal plate of said first cell is electrically connected to said positive terminal and the negative terminal plate of said last plate is electrically connected to the negative terminal.