CA1090877A - Improved separator for batteries - Google Patents
Improved separator for batteriesInfo
- Publication number
- CA1090877A CA1090877A CA289,556A CA289556A CA1090877A CA 1090877 A CA1090877 A CA 1090877A CA 289556 A CA289556 A CA 289556A CA 1090877 A CA1090877 A CA 1090877A
- Authority
- CA
- Canada
- Prior art keywords
- storage battery
- concaves
- embossed
- microporous sheet
- separator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/44—Fibrous material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/417—Polyolefins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/463—Separators, membranes or diaphragms characterised by their shape
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Cell Separators (AREA)
Abstract
STORAGE BATTERY AND PROCESS FOR MANUFACTURING THE SAME
Abstract of the Disclosure A storage battery includes an embossed separator disposed between negative and positive plates, the embossed separator having a plurality of concaves pro-vided on a microporous sheet and channels connecting the concaves to one another and having a depth shallower than the concaves. The process for making the embossed separator includes passing the microporous sheet between a metallic embossing roll and an elastic roll and then cooling it without applying a tension.
Abstract of the Disclosure A storage battery includes an embossed separator disposed between negative and positive plates, the embossed separator having a plurality of concaves pro-vided on a microporous sheet and channels connecting the concaves to one another and having a depth shallower than the concaves. The process for making the embossed separator includes passing the microporous sheet between a metallic embossing roll and an elastic roll and then cooling it without applying a tension.
Description
7~
This invention relates to storage batteries, more particularly to a lead-acid storage battery and a method of manufacturing the same.
An object of the present invention is to provide a storage battery having favorable high rate discharge characteristics and long life, and a process for manu-facturing the sa~e.
Another object of the present invention is to provide a storage battery which can be mass produced and a process for manufacturing the same.
A further object of the present invention is to provide a storage battery which is inexpensive and easy to make, and a process for manufacturing the same.
According to the invention, there is provided a storage battery formed by arranging between negative and positive plates an embossed separator having a plurality of concaves provided on a thin microporous sheet and channels connecting said concaves with each other and shallower than the concaves.
The present invention can be more easily understood - by referring to the following drawings and description.
Fig. 1 is a partly sectioned perspective view of a storage battery of the present invention;
Fig. 2 is a partial plan view of an embossed separator forming the storage battery of the present invention;
Fig. 3 is a greatly enlarged partial perspective view of the embossed separator of Fig. 2;
Fig. 4 is an even more enlarged sectional view of the embossed separator taken substantially along line A-A' of Fig. 2;
Fig. 5 is a partial perspective view of a conventional
This invention relates to storage batteries, more particularly to a lead-acid storage battery and a method of manufacturing the same.
An object of the present invention is to provide a storage battery having favorable high rate discharge characteristics and long life, and a process for manu-facturing the sa~e.
Another object of the present invention is to provide a storage battery which can be mass produced and a process for manufacturing the same.
A further object of the present invention is to provide a storage battery which is inexpensive and easy to make, and a process for manufacturing the same.
According to the invention, there is provided a storage battery formed by arranging between negative and positive plates an embossed separator having a plurality of concaves provided on a thin microporous sheet and channels connecting said concaves with each other and shallower than the concaves.
The present invention can be more easily understood - by referring to the following drawings and description.
Fig. 1 is a partly sectioned perspective view of a storage battery of the present invention;
Fig. 2 is a partial plan view of an embossed separator forming the storage battery of the present invention;
Fig. 3 is a greatly enlarged partial perspective view of the embossed separator of Fig. 2;
Fig. 4 is an even more enlarged sectional view of the embossed separator taken substantially along line A-A' of Fig. 2;
Fig. 5 is a partial perspective view of a conventional
- 2 -`
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embossed separator;
Fig. 6 is a partial vertical sectional view of the separator of Fig. 5 as arranged in close contact between negative and positive plates; and Fig. 7 is a diagrammatical view showing a process used for manufacturing an embossed separator forming a storage - 2a -' ~
~ ~t~
battery of the present invention.
In Fig. 1, a storage battery 1 comprises negative plates 3, embossed separators 4 of a special shape, positive plates 5 and an electrolyte Inot illustrated) housed in an electric battery container 2, a lid 6 covering the container.
A feature of the present invention involves the use of embossed separators of a special shape in the storage battery. Each embossed separator 4 is formed of a plur-ality of concave portions 7, channels 8 connecting theconcave portions and shallower in depth as compared thereto and substantially projecting webs g on one surface thereof. The separator is in the form of a microporous sheet 4, having convex portions corresponding to the concave portions, linear projections corresponding to -the channels and concaved webs corresponding to the projecting webs on the other surface. As a whole, this embossed separator is formed as a concave-convex element and has an apparent thickness several times as large as the thin original microporous sheet from which it is made. The thin microporous sheet is a microporous sheet containing a synthetic resin or a sheet of a thickness of less than 0.5mm comprising a nonwoven fabric or the like made of fine synthetic fibers of a diameter of less than 5 microns. It is preferable that each concave portion be diamond-shaped and having a side length in the range of 1 to lOmm., or be substantially in the form of a circle, an ellipse, a square or a rectangle of a size substantially corresponding to such range. It is preferable that the distance between the concave portions be in the range of 4 to 20mm. and that the width of the channel be in the range ~.V~ 7~
of 0.2 to 2mm. If they are outside these ranges, it will be difficult to form concave and convex portions on the thin microporous sheet and, even if they can be formed, no embossed separator of a desired apparent thickness main-taining a distance between negative and positive plates will be obtained, the pore diameter of the micropores will be reduced and made more filmy than is necessary, the electric resistance will be high and the battery perfor-mance will not be satisfactory.
The embossed separator ~ is obtained by passing a microporous sheet under an applied pressure between an elastic roll and a heated metallic embossing roll having a pattern of a plurality of projections and linear projections connecting the projections and lower than them. The detailed manufacturing process shall be described later.
The thus made embossed separator is formed to be concave-convex as a whole so as to have an apparent thickness. When such embossed separators are used in a storage battery, the electric resistance is so low that the battery performance is favorable. Further, this embossed separator has so many comparatively small con-cave portions as to render it highly elastic. When arranged between negative and positive plates, the separator effectively applies a force of pressure par-ticularly to the active material of the positive plate and is very effective in preventing the active material from shedding off. As a result, it has an advantage of further improving the life of the battery. Further, when this embossed separator 4 is arranged in close contact between the negative plate 3 and positive plate 5, due to concave ~., '
7~
embossed separator;
Fig. 6 is a partial vertical sectional view of the separator of Fig. 5 as arranged in close contact between negative and positive plates; and Fig. 7 is a diagrammatical view showing a process used for manufacturing an embossed separator forming a storage - 2a -' ~
~ ~t~
battery of the present invention.
In Fig. 1, a storage battery 1 comprises negative plates 3, embossed separators 4 of a special shape, positive plates 5 and an electrolyte Inot illustrated) housed in an electric battery container 2, a lid 6 covering the container.
A feature of the present invention involves the use of embossed separators of a special shape in the storage battery. Each embossed separator 4 is formed of a plur-ality of concave portions 7, channels 8 connecting theconcave portions and shallower in depth as compared thereto and substantially projecting webs g on one surface thereof. The separator is in the form of a microporous sheet 4, having convex portions corresponding to the concave portions, linear projections corresponding to -the channels and concaved webs corresponding to the projecting webs on the other surface. As a whole, this embossed separator is formed as a concave-convex element and has an apparent thickness several times as large as the thin original microporous sheet from which it is made. The thin microporous sheet is a microporous sheet containing a synthetic resin or a sheet of a thickness of less than 0.5mm comprising a nonwoven fabric or the like made of fine synthetic fibers of a diameter of less than 5 microns. It is preferable that each concave portion be diamond-shaped and having a side length in the range of 1 to lOmm., or be substantially in the form of a circle, an ellipse, a square or a rectangle of a size substantially corresponding to such range. It is preferable that the distance between the concave portions be in the range of 4 to 20mm. and that the width of the channel be in the range ~.V~ 7~
of 0.2 to 2mm. If they are outside these ranges, it will be difficult to form concave and convex portions on the thin microporous sheet and, even if they can be formed, no embossed separator of a desired apparent thickness main-taining a distance between negative and positive plates will be obtained, the pore diameter of the micropores will be reduced and made more filmy than is necessary, the electric resistance will be high and the battery perfor-mance will not be satisfactory.
The embossed separator ~ is obtained by passing a microporous sheet under an applied pressure between an elastic roll and a heated metallic embossing roll having a pattern of a plurality of projections and linear projections connecting the projections and lower than them. The detailed manufacturing process shall be described later.
The thus made embossed separator is formed to be concave-convex as a whole so as to have an apparent thickness. When such embossed separators are used in a storage battery, the electric resistance is so low that the battery performance is favorable. Further, this embossed separator has so many comparatively small con-cave portions as to render it highly elastic. When arranged between negative and positive plates, the separator effectively applies a force of pressure par-ticularly to the active material of the positive plate and is very effective in preventing the active material from shedding off. As a result, it has an advantage of further improving the life of the battery. Further, when this embossed separator 4 is arranged in close contact between the negative plate 3 and positive plate 5, due to concave ~., '
3~ 7~
portions 7 and shallower channels 8 provided on the embossed separator 4, the space between the embossed separator 4 and the negative plate 3 or positive plate 5 forms a continued passage. This results in an easy diffusion of the electrolyte, easy removal of gases generated from the plates during the use of the battery and smooth electrochemical reaction, thereby improving the battery perEormance. In the conventional embossed separator 4', a plurality of concave portions 7' are merely formed as shown in Figs. 5 and 6. Therefore, when the embossed separator 4' is arranged in close contact between a negative plate 3' and positive plate 5', concave portions 7' become sealed chambers from which gases will be difficult to escape and therefore remain to prevent the movement of ions and, as a result, the battery performance will deteriorate extremely.
Another feature of the present invention is that a part or all of the micropores of the plurality of concave portions 7 or channels formed on the embossed separator 4 are reduced or are made filmy. Therefore, the microporous sheet l-is made of a synthetic resin or a mixture of a synthetic resin with an inorganic filler. Polyvinyl chloride, polystyrene and polyvinylidene fluoride are approriate types of synthetic resins to be used. Many other resins, the micropores of which can be reduced or made filmy micropores when heated, can be used. The reduction or ~ilming of the micropores will be influenced by the heating temperature of the aforedescribed metaIlic embossing roll passing the microporous sheet. The higher the temperature, the more the reduction or filming of the micropores and the more filmy the sheet. On the other -, ~P~i .
7~
hand, the more filmy the concaves or channels, the higher the elasticity of the embossed separator but the higher the electric resistance.
The formation of a sheet high in elasticity is of a microporous sheet which is made of a compound of a microporous synthetic resin with a nonwoven or woven fabric of synthetic fibers, in which only the synthetic resin forming micropores will melt but the synthetic fibers will not melt and which is optimum to bring about favorable results in the battery performance and life.
When such embossed separator having a high elasticity is arranged between negative and positive plates, it will be very effective in preventing particularly the active material of the positive plate from shedding off and will be advantageous in further improving the performance and life of the battery as a result.
A further feature of the present invention is to assemble a storage battery by arranging the embossed separator 4 between the negative plate 3 and positive plate 5 so that the channels 8 formed on the separator may be diagonal to the vertical direction of the plates. The removal of the gases generated during the use of the battery will therefore be further improved and the battery performance will further improve.
A still further feature of the present invention involves contacting the tips 7a of concave portions 7 with the positive plate and contacting convex portions 9 with the negative plate. It is the arrangement of the embossed separator wherein spaces formed between microporous sheet and the plates allow for easy diffusion of the electro-ly~te and the removal of the gases, and the direct contact ~ 7t~
of filmy part 7a on the positive plates give strong oxidation resistance, thereby improving the battery performance and life.
A still further feature of the present invention involves a ne~ process for manufacturing storage batteries. It comprises the step of forming concaves and convexes by passing a thin microporous sheet between a flat surface elastic roll and a heated metallic embossing roll having a pattern of a plurality of projections and linear projections connecting such projections with each other and lower than them, the step of then cooling under no applied tension the microporous sheet which has the concaves and convexes already formed on it and the step of assembling a storage battery with the thus obtained embossed separators. Fig. 7 is a diagrammatical view showing a process for manufacturing a storage battery and particularly a process for manufacturing an embossed separator. For example, a thin microporous sheet ll is passed, under an applied pressure, between a metallic embossing roll 12 having the aforedescribed pattern and heated to a predetermined temperature, and an elastic roll 13 having a flat surface. Therefore, the plurality of the higher projections connecting said higher projections with each other on the metallic embossing roll will contact the microporous sheet under the applied pressure. As a result, the diameters of the micropores of the sheet, as at 7, and channels 8 formed on the microporous sheet will be reduced or made filmy and other webs 9 will retain the micropores as they are. This is because of the use of flat elastic roll 13 which may be, for example, a rubber roll.
As a result, favorable embossed separators for storage ;~i J ~ 7Y~
batteries low in electric resistance and high in battery discharge characteristic will be obtained. Then the embossed narrow long microporous sheet 11' is passed under no applied tension between a pair of cooling rolls 14 and 14'. If a tension is applied, concaves and channels formed on the microporous sheet 11' will be deformed or will be reduced in apparent thickness. Thus no favorable result will be brought about in the performance and life of the battery. The microporous sheet 11" having passed through the cooling rolls 14 and 14' passes through the next step when it is cut into a required size for use as separators 4. A storage battery is assembled by arranging such embossed separator between negative and positive plates. Some examples on the aforedescribed embossed separators are shown in the following.
Example 1:
A thin microporous sheet having a polyester non-woven fabric of a thickness of 0.2mm. and chlorinated polyvinyl p r ~A c ~ p G~ I
chloride as the ~nclp~ microporous components and an average micropore diameter of 0.6 micron was made, was passed at a speed of lOm./min. under a nipping pressure of 78kg/cm2. between a metallic embossing roll having a pattern comprising a plurality of projections of which the shape of the tip was in the form of a diamond having a side length of 2mm., the height was 1.8mm. and the distance between the centers of projection was 5mm. and linear projections connecting the projections with each other, having a width of the tip of 0.2mm. and lower than the projections and heated to a temperature of 130C., and a flat surface rubber roll made of neoprene (a synthetic rubber3 of a hardness of 80 flat on the surface. The sheet ~087~
was then passed between a pair of cooling rolls under no applied tension to obtain an embossed separator of an apparent thickness of 0.8mm. provided with nonporous filmy concaves and nonporous filmy channels of a depth of 0.3mm.
and a width of 0.2mm. connecting the concaves with each other.
This embossed separator was so low in the electric resistance in dilute sul~uric acid of a specific gravity of 1.20 as to be of O.OOlOQ/dm2/sheet, was of 130H/sheet in the resistance to electric oxidation and was twice as strong as a conventional paper resin bonded separator.
Further, its elasticity was so high that, when a load of 20kg/lOOcm2. was applied for 3 months, the deformation was 10%. It was superior to a conventional glass fiber mat.
When a battery was assembled by setting these embossed separators so that the tips (conve~es on the other surface~ of the concaves contact the positive plate and the channels connecting the concaves with each other were diagonal to the vertical direction and was tested, a distance between the plates could be held by the plurality the elastic concaves provided on the embossed separator, the active material could be prevented from shedding o~f, the movement of the electrolyte could be easy by the shallow communicating channels connecting the plurality of the concaves with each other and the gases generated from the plates could be moved through the plurality of the concaves and shal:Low channels of the aforementioned separators and could be removed out of the electrolyte.
Particularly, at a high rate discharge, high performance not seen in any conventional separator was shown. There J~1~ 77 were increases of 20~ in the battery capacity and 8~
in the voltage characteristic. The life of the storage battery of the present invention in which these embossed separators were used was 50% longer than of a battery in which ribbed separators were used. Further~ as the channels of the embossed separator are diagonally arranged, the gases in clearances between separator and plates could be removed very well. As compared with a conventional ribbed separator or separator with glass fiber mat, the embossed separator applied to the present invention is made by the mere deformation of a thin microporous sheet and has no material added, therefore, its cost reduction of 30% is possible. It is so simple to handle in assembling a storage battery by enveloping plate with this paper like flexible embossed separator that lt is easy to make the storage battery.
Example 2:
A microporous sheet of a polyester nonwoven fabric of a thickness of 0.2mm. using fibers with diameter of less than 5.0 micron was made, was passed between a metallic embossing roll having a pattern of a plurality of projec-tions of a shape of the tip in the form of a circle of a diameter of 3mm. connected with each other through linear projections ha~ing a width of the tip of lmm. and lower than the projections and heated to 120C., and a rubber roll, and was then passed between a pair of cooling rolls under no applied tension. As a result, an embossed separator of an apparent thickness of 0.7mm. was obtained, on which a plurality of circular concaves and channels connecting them with each other were formed. This embossed separator was so low in the electric resistance ~.
~ ~O ~ 7~
in dilute sulfuric acid of a specific gravity of 1.20 as to be of 0.0008Q/cm2./sheet and was of 60H/sheet in the resistance to electric oxidation. When these embossed separators were incorporated into a battery in such a manner the tips of the concaves contacted the positive plates and the channels were disposed diagonally rela-tively to the vertical direction and the battery was tested, the capacity increased by 13% and the voltage characteristics increased by 10~. Further, there were the same advantages as in Example 1.
Example 3:
A uniform mixture consisting of 15% by volume high molecular weight polyethylene, 15% by volume silica as a filler, 1% by volume carbon black and 69~ by volum~
petroleum oil as a plasticizer was made into a sheet.
The sheet was dipped in a solvent hexane to extract the petroleum oil to make a thin microporous sheet of a thickness of 0.3mm. This microporous sheet was passed between a metallic embossing roll having a pattern with a plurality of projections of a shape of the tip in the form of a diamond of a side length of 2mm. and of a distance between the projections of 5mm. connected with each oth~r through linear projections having a width of the tip of 0.2mm. and lower than the projections and heated to 160C., and a rubber roll, and was then passed between a pair of cooling rolls to obtain an embossed separator of an apparent thickness of 0.8mm. having a plurality of diamond-shaped concaves and channels connecting them with each other~ This embossed separator was of 0.0017Q/dm ./sheet in the electric resistance in dilute sulfuric acid of a specific gravity of 1.20 and of more `` ~V ~ 7 ~
than 450H/sheet in the resistance to electric oxidation.
Just this embossed separator was rather poor in the elasticity and was therefore comparatively short in the life but its life increased to be 20% longer than of the conventional ribbed separator. Further, there were the same advantages as in Example 1.
Thus the storage battery of the present invention and the process for manufacturing the same have various advantages that the performance and life of the storage battery are remarkably improved and that the battery is cheap, is easy to make and is adapted to be mass-produced.
It is needless to say that various modifications of the product and alterations of the manufacturing process are possible in the range not deviating from the spirit of the present invention. For example, the material to be used for the thin microporous sheet is not limited to the examples. Also, the means of cooling the thin microporous sheet after having passed through the metallic embossing roll and elastic roll is not limited to contacting the cooling rolls in the examples but may be by air-cooling~
~' . .
portions 7 and shallower channels 8 provided on the embossed separator 4, the space between the embossed separator 4 and the negative plate 3 or positive plate 5 forms a continued passage. This results in an easy diffusion of the electrolyte, easy removal of gases generated from the plates during the use of the battery and smooth electrochemical reaction, thereby improving the battery perEormance. In the conventional embossed separator 4', a plurality of concave portions 7' are merely formed as shown in Figs. 5 and 6. Therefore, when the embossed separator 4' is arranged in close contact between a negative plate 3' and positive plate 5', concave portions 7' become sealed chambers from which gases will be difficult to escape and therefore remain to prevent the movement of ions and, as a result, the battery performance will deteriorate extremely.
Another feature of the present invention is that a part or all of the micropores of the plurality of concave portions 7 or channels formed on the embossed separator 4 are reduced or are made filmy. Therefore, the microporous sheet l-is made of a synthetic resin or a mixture of a synthetic resin with an inorganic filler. Polyvinyl chloride, polystyrene and polyvinylidene fluoride are approriate types of synthetic resins to be used. Many other resins, the micropores of which can be reduced or made filmy micropores when heated, can be used. The reduction or ~ilming of the micropores will be influenced by the heating temperature of the aforedescribed metaIlic embossing roll passing the microporous sheet. The higher the temperature, the more the reduction or filming of the micropores and the more filmy the sheet. On the other -, ~P~i .
7~
hand, the more filmy the concaves or channels, the higher the elasticity of the embossed separator but the higher the electric resistance.
The formation of a sheet high in elasticity is of a microporous sheet which is made of a compound of a microporous synthetic resin with a nonwoven or woven fabric of synthetic fibers, in which only the synthetic resin forming micropores will melt but the synthetic fibers will not melt and which is optimum to bring about favorable results in the battery performance and life.
When such embossed separator having a high elasticity is arranged between negative and positive plates, it will be very effective in preventing particularly the active material of the positive plate from shedding off and will be advantageous in further improving the performance and life of the battery as a result.
A further feature of the present invention is to assemble a storage battery by arranging the embossed separator 4 between the negative plate 3 and positive plate 5 so that the channels 8 formed on the separator may be diagonal to the vertical direction of the plates. The removal of the gases generated during the use of the battery will therefore be further improved and the battery performance will further improve.
A still further feature of the present invention involves contacting the tips 7a of concave portions 7 with the positive plate and contacting convex portions 9 with the negative plate. It is the arrangement of the embossed separator wherein spaces formed between microporous sheet and the plates allow for easy diffusion of the electro-ly~te and the removal of the gases, and the direct contact ~ 7t~
of filmy part 7a on the positive plates give strong oxidation resistance, thereby improving the battery performance and life.
A still further feature of the present invention involves a ne~ process for manufacturing storage batteries. It comprises the step of forming concaves and convexes by passing a thin microporous sheet between a flat surface elastic roll and a heated metallic embossing roll having a pattern of a plurality of projections and linear projections connecting such projections with each other and lower than them, the step of then cooling under no applied tension the microporous sheet which has the concaves and convexes already formed on it and the step of assembling a storage battery with the thus obtained embossed separators. Fig. 7 is a diagrammatical view showing a process for manufacturing a storage battery and particularly a process for manufacturing an embossed separator. For example, a thin microporous sheet ll is passed, under an applied pressure, between a metallic embossing roll 12 having the aforedescribed pattern and heated to a predetermined temperature, and an elastic roll 13 having a flat surface. Therefore, the plurality of the higher projections connecting said higher projections with each other on the metallic embossing roll will contact the microporous sheet under the applied pressure. As a result, the diameters of the micropores of the sheet, as at 7, and channels 8 formed on the microporous sheet will be reduced or made filmy and other webs 9 will retain the micropores as they are. This is because of the use of flat elastic roll 13 which may be, for example, a rubber roll.
As a result, favorable embossed separators for storage ;~i J ~ 7Y~
batteries low in electric resistance and high in battery discharge characteristic will be obtained. Then the embossed narrow long microporous sheet 11' is passed under no applied tension between a pair of cooling rolls 14 and 14'. If a tension is applied, concaves and channels formed on the microporous sheet 11' will be deformed or will be reduced in apparent thickness. Thus no favorable result will be brought about in the performance and life of the battery. The microporous sheet 11" having passed through the cooling rolls 14 and 14' passes through the next step when it is cut into a required size for use as separators 4. A storage battery is assembled by arranging such embossed separator between negative and positive plates. Some examples on the aforedescribed embossed separators are shown in the following.
Example 1:
A thin microporous sheet having a polyester non-woven fabric of a thickness of 0.2mm. and chlorinated polyvinyl p r ~A c ~ p G~ I
chloride as the ~nclp~ microporous components and an average micropore diameter of 0.6 micron was made, was passed at a speed of lOm./min. under a nipping pressure of 78kg/cm2. between a metallic embossing roll having a pattern comprising a plurality of projections of which the shape of the tip was in the form of a diamond having a side length of 2mm., the height was 1.8mm. and the distance between the centers of projection was 5mm. and linear projections connecting the projections with each other, having a width of the tip of 0.2mm. and lower than the projections and heated to a temperature of 130C., and a flat surface rubber roll made of neoprene (a synthetic rubber3 of a hardness of 80 flat on the surface. The sheet ~087~
was then passed between a pair of cooling rolls under no applied tension to obtain an embossed separator of an apparent thickness of 0.8mm. provided with nonporous filmy concaves and nonporous filmy channels of a depth of 0.3mm.
and a width of 0.2mm. connecting the concaves with each other.
This embossed separator was so low in the electric resistance in dilute sul~uric acid of a specific gravity of 1.20 as to be of O.OOlOQ/dm2/sheet, was of 130H/sheet in the resistance to electric oxidation and was twice as strong as a conventional paper resin bonded separator.
Further, its elasticity was so high that, when a load of 20kg/lOOcm2. was applied for 3 months, the deformation was 10%. It was superior to a conventional glass fiber mat.
When a battery was assembled by setting these embossed separators so that the tips (conve~es on the other surface~ of the concaves contact the positive plate and the channels connecting the concaves with each other were diagonal to the vertical direction and was tested, a distance between the plates could be held by the plurality the elastic concaves provided on the embossed separator, the active material could be prevented from shedding o~f, the movement of the electrolyte could be easy by the shallow communicating channels connecting the plurality of the concaves with each other and the gases generated from the plates could be moved through the plurality of the concaves and shal:Low channels of the aforementioned separators and could be removed out of the electrolyte.
Particularly, at a high rate discharge, high performance not seen in any conventional separator was shown. There J~1~ 77 were increases of 20~ in the battery capacity and 8~
in the voltage characteristic. The life of the storage battery of the present invention in which these embossed separators were used was 50% longer than of a battery in which ribbed separators were used. Further~ as the channels of the embossed separator are diagonally arranged, the gases in clearances between separator and plates could be removed very well. As compared with a conventional ribbed separator or separator with glass fiber mat, the embossed separator applied to the present invention is made by the mere deformation of a thin microporous sheet and has no material added, therefore, its cost reduction of 30% is possible. It is so simple to handle in assembling a storage battery by enveloping plate with this paper like flexible embossed separator that lt is easy to make the storage battery.
Example 2:
A microporous sheet of a polyester nonwoven fabric of a thickness of 0.2mm. using fibers with diameter of less than 5.0 micron was made, was passed between a metallic embossing roll having a pattern of a plurality of projec-tions of a shape of the tip in the form of a circle of a diameter of 3mm. connected with each other through linear projections ha~ing a width of the tip of lmm. and lower than the projections and heated to 120C., and a rubber roll, and was then passed between a pair of cooling rolls under no applied tension. As a result, an embossed separator of an apparent thickness of 0.7mm. was obtained, on which a plurality of circular concaves and channels connecting them with each other were formed. This embossed separator was so low in the electric resistance ~.
~ ~O ~ 7~
in dilute sulfuric acid of a specific gravity of 1.20 as to be of 0.0008Q/cm2./sheet and was of 60H/sheet in the resistance to electric oxidation. When these embossed separators were incorporated into a battery in such a manner the tips of the concaves contacted the positive plates and the channels were disposed diagonally rela-tively to the vertical direction and the battery was tested, the capacity increased by 13% and the voltage characteristics increased by 10~. Further, there were the same advantages as in Example 1.
Example 3:
A uniform mixture consisting of 15% by volume high molecular weight polyethylene, 15% by volume silica as a filler, 1% by volume carbon black and 69~ by volum~
petroleum oil as a plasticizer was made into a sheet.
The sheet was dipped in a solvent hexane to extract the petroleum oil to make a thin microporous sheet of a thickness of 0.3mm. This microporous sheet was passed between a metallic embossing roll having a pattern with a plurality of projections of a shape of the tip in the form of a diamond of a side length of 2mm. and of a distance between the projections of 5mm. connected with each oth~r through linear projections having a width of the tip of 0.2mm. and lower than the projections and heated to 160C., and a rubber roll, and was then passed between a pair of cooling rolls to obtain an embossed separator of an apparent thickness of 0.8mm. having a plurality of diamond-shaped concaves and channels connecting them with each other~ This embossed separator was of 0.0017Q/dm ./sheet in the electric resistance in dilute sulfuric acid of a specific gravity of 1.20 and of more `` ~V ~ 7 ~
than 450H/sheet in the resistance to electric oxidation.
Just this embossed separator was rather poor in the elasticity and was therefore comparatively short in the life but its life increased to be 20% longer than of the conventional ribbed separator. Further, there were the same advantages as in Example 1.
Thus the storage battery of the present invention and the process for manufacturing the same have various advantages that the performance and life of the storage battery are remarkably improved and that the battery is cheap, is easy to make and is adapted to be mass-produced.
It is needless to say that various modifications of the product and alterations of the manufacturing process are possible in the range not deviating from the spirit of the present invention. For example, the material to be used for the thin microporous sheet is not limited to the examples. Also, the means of cooling the thin microporous sheet after having passed through the metallic embossing roll and elastic roll is not limited to contacting the cooling rolls in the examples but may be by air-cooling~
~' . .
Claims (9)
1. A storage battery formed by arranging between negative and positive plates an embossed separator having a plurality of concaves provided on a thin microporous sheet and channels connecting said concaves with each other and shallower than the concaves.
2. The storage battery according to claim 1 wherein said thin microporous sheet is of a thickness of less than 0.5mm. and contains a synthetic resin.
3. The storage battery according to claim 1 wherein said thin microporous sheet is made of a compound of a microporous synthetic resin with a nonwoven or woven fabric of synthetic fibers.
4. The storage battery according to claim 1 wherein said thin microporous sheet consists of concaves of a shape in the form of a diamond of a side length in the range of 1 to 10mm. or a circle, ellipse or square of a size substantially corresponding to it.
5. The storage battery according to claim 1 wherein the distance between said concaves is in the range of 4 to 20mm.
6. The storage battery according to claim 1 wherein the bottom width of said channel is in the range of 0.2 to 2mm.
7. The storage battery according to claim 1 wherein all or apart of the micropores of said concaves or channels provided on said thin microporous sheet are reduced or made nonporous filmy.
8. The storage battery according to claim 1 wherein said channels provided on the embossed separator arranged between the negative and positive plates are so formed as to be diagonal to the vertical direction.
9. The storage battery according to claim 1 wherein the tips of said concaves provided on the embossed separator are so arranged as to contact the positive plate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13977376A JPS5364734A (en) | 1976-11-20 | 1976-11-20 | Battery |
| JP139773/1976 | 1976-11-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1090877A true CA1090877A (en) | 1980-12-02 |
Family
ID=15253066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,556A Expired CA1090877A (en) | 1976-11-20 | 1977-10-26 | Improved separator for batteries |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5364734A (en) |
| CA (1) | CA1090877A (en) |
| GB (1) | GB1568776A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS594451Y2 (en) * | 1977-06-20 | 1984-02-08 | 安倍川製紙株式会社 | Separator for lead-acid batteries |
| JPS646360A (en) * | 1987-06-29 | 1989-01-10 | Yuasa Battery Co Ltd | Gel type enclosed lead storage battery |
| JP2020077480A (en) * | 2018-11-06 | 2020-05-21 | 旭化成株式会社 | Separator having fine pattern, wound body, and nonaqueous electrolyte secondary battery |
-
1976
- 1976-11-20 JP JP13977376A patent/JPS5364734A/en active Pending
-
1977
- 1977-10-26 CA CA289,556A patent/CA1090877A/en not_active Expired
- 1977-11-17 GB GB47911/77A patent/GB1568776A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1568776A (en) | 1980-06-04 |
| JPS5364734A (en) | 1978-06-09 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |