U.S. patent application number 15/363591 was filed with the patent office on 2017-03-16 for laminated oxidation protected separator.
The applicant listed for this patent is Daramic, LLC. Invention is credited to Jeffrey K. Chambers, Pierre A. Hauswald, Eric H. Miller, John R. Timmons, J. Kevin Whear.
Application Number | 20170077479 15/363591 |
Document ID | / |
Family ID | 51488185 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170077479 |
Kind Code |
A1 |
Miller; Eric H. ; et
al. |
March 16, 2017 |
LAMINATED OXIDATION PROTECTED SEPARATOR
Abstract
A battery separator for a lead acid battery addresses the issues
of acid stratification and separator oxidation arising from
contaminants. The separator includes a microporous membrane and a
diffusive mat affixed thereto. The diffusive mat has a three hour
wick of: at least about 2.5 cm. The diffusive mat may be made of
synthetic fibers, glass fibers, natural fibers, and combinations
thereof. The diffusive mat may include silica. The separator may
include a rubber.
Inventors: |
Miller; Eric H.; (Philpot,
KY) ; Whear; J. Kevin; (Utica, KY) ; Timmons;
John R.; (Owensboro, KY) ; Chambers; Jeffrey K.;
(Philpot, KY) ; Hauswald; Pierre A.; (Dorlisheim,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Daramic, LLC |
Charlotte |
NC |
US |
|
|
Family ID: |
51488185 |
Appl. No.: |
15/363591 |
Filed: |
November 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14200066 |
Mar 7, 2014 |
|
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15363591 |
|
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61774144 |
Mar 7, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/06 20130101;
H01M 2/18 20130101; H01M 10/12 20130101; H01M 2/1626 20130101; H01M
2/1613 20130101; H01M 2/1686 20130101; H01M 2/1653 20130101; Y02E
60/10 20130101 |
International
Class: |
H01M 2/16 20060101
H01M002/16; H01M 2/18 20060101 H01M002/18; H01M 10/12 20060101
H01M010/12 |
Claims
1-17. (canceled)
18. A battery separator for a flooded lead acid battery, wherein
the battery separator comprises: a microporous membrane comprising
polyethylene and silica; and a positive active material (PAM)
retention mat, said PAM retention mat comprising fine glass fibers,
wherein said PAM retention mat is a nonwoven mat or a woven mat,
and wherein said PAM retention mat faces or is in contact with a
positive electrode or PAM of said flooded lead acid battery,
wherein the battery separator decelerates corrosion of at least one
electrode of the flooded lead acid battery and/or prevents shedding
of PAM from the positive electrode of the flooded lead acid
battery, and wherein the flooded lead acid battery operates at a
high depth of discharge (DoD).
19. The battery separator according to claim 18, wherein the
flooded lead acid battery is selected from the group consisting of
a dry charge battery, an inverter battery, an enhanced flooded
battery (EFB), an ISS battery, a stationary battery, a golf cart
battery, and combinations thereof.
20. The battery separator according to claim 18, wherein the PAM
retention mat has a thickness of about 0.2 mm to less than about
0.5 mm.
21. The battery separator according to claim 18, wherein the PAM
retention mat comprises a particulate filler, and said filler
includes silica.
22. The battery separator according to claim 18, wherein the PAM
retention mat further includes a coating.
23. The battery separator according to claim 18, wherein the
microporous membrane further comprises rubber and/or latex.
24. The battery separator according to claim 18, wherein the
battery separator is an envelope separator and envelopes a positive
plate, a negative plate, or both a positive plate and a negative
plate of the flooded lead acid battery.
25. The battery separator according to claim 18, wherein the
battery separator is a pocket, a sleeve, a leaf, or an "S"
wrap.
26. An EFB or a golf cart battery comprising the battery separator
of claim 18.
27. An EFB or a golf cart battery with increased cycle life
comprising the battery separator of claim 18.
28. The battery separator according to claim 18, wherein the
microporous membrane has a ribbed profile.
29. The battery separator according to claim 28, wherein the ribbed
profile includes ribs running in a machine direction on a side of
the microporous membrane facing the positive electrode or PAM of
the flooded lead acid battery.
30. The battery separator according to claim 29, wherein the ribbed
profile further includes ribs running in a cross machine direction
on a side of the microporous membrane facing a negative electrode
or negative active material (NAM) of the flooded lead acid
battery.
31. The battery separator according to claim 18, wherein the
battery separator reduces acid stratification in the flooded lead
acid battery.
32. The battery separator according to claim 18, wherein the PAM
retention mat has a three hour wick of at least about 2.5 cm.
33. The battery separator according to claim 18, wherein the PAM
retention mat has a three hour wick in a range of about 2.5 cm to
about 10.0 cm.
34. The battery separator according to claim 18, wherein the PAM
retention mat further comprises synthetic fibers, synthetic wood
pulp, glass fibers, natural fibers, coated fibers, or combinations
thereof.
35. The battery separator according to claim 18, wherein the
microporous membrane is laminated to the PAM retention mat.
36. The battery separator according to claim 18, wherein the PAM
retention mat is a nonwoven mat.
37. The battery separator according to claim 18, wherein the PAM
retention mat is a woven mat.
38. The battery separator according to claim 18, wherein the PAM
retention mat has at least one of: a pore size of greater than
about 1 micron; an MD stiffness of greater than about 90 mN; a CMD
stiffness of greater than about 45 mN; a thickness of equal to or
greater than about 0.2 mm; and a basis weight of greater than about
35 gsm.
39. A flooded lead acid battery comprising: a negative electrode, a
positive electrode, an electrolyte, and a battery separator,
wherein said battery separator comprises a microporous membrane
comprising polyethylene and silica, and a positive active material
(PAM) retention mat affixed or laminated thereto, said PAM
retention mat comprising fine glass fibers, wherein said PAM
retention mat is a nonwoven mat or a woven mat, wherein said PAM
retention mat faces or is in contact with said positive electrode
or PAM of said battery, wherein the PAM retention mat has a three
hour wick of at least about 2.5 cm, and wherein the battery
separator prevents shedding of PAM from the positive electrode of
the battery.
40. The flooded lead acid battery of claim 39, wherein said battery
is a dry charge battery, an inverter battery, an enhanced flooded
battery (EFB), an ISS battery, a stationary battery, or a golf cart
battery.
41. The flooded lead acid battery of claim 39, wherein said PAM
retention mat is a nonwoven mat less than about 0.5 mm thick.
42. The flooded lead acid battery of claim 39, wherein said PAM
retention mat is a woven mat less than about 0.5 mm thick.
43. A battery separator for a flooded lead acid battery, wherein
said battery separator comprises a microporous polymer membrane,
and a positive active material (PAM) retention mat affixed or
laminated thereto, said PAM retention mat comprising fine glass
fibers, wherein said PAM retention mat is a nonwoven mat or a woven
mat less than about 0.5 mm thick, wherein said PAM retention mat
faces or is in contact with said positive electrode or PAM of said
battery, and wherein the battery separator prevents shedding of PAM
from the positive electrode of the battery when it operates at a
high depth of discharge (DoD) and wherein the battery operating at
a high DoD is selected from the group consisting of a dry charge
battery, an inverter battery, an enhanced flooded battery (EFB), an
ISS battery, a stationary battery, a golf cart battery, and
combinations thereof.
Description
RELATED APPLICATION
[0001] This application claims the benefit of co-pending U.S.
provisional application Ser. No. 61/774144 filed Mar. 7, 2013,
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is directed to a battery separator for
a lead/acid batteries having a diffusive mat affixed to a
microporous membrane.
BACKGROUND
[0003] In abusive heat applications (e.g., congested regions with
high traffic, tropical or desert regions, outside storage
applications and the like), batteries (e.g., lead acid batteries,
particularly flooded lead acid (FLA) batteries) are prone to
electrolyte loss. The electrolyte may be a mixture of water and
acid (e.g., sulfuric acid). Loss of the electrolyte exposes the
electrodes to the gaseous environment contained within the battery
head-space and heat, which can ultimately lead to dry-out of the
electrode plates and, in turn, accelerated corrosion of the
electrodes that leads to premature battery failure.
[0004] Further, during charging of the battery (e.g., a lead acid
battery), the acid in the electrolyte may become stratified. Acid
stratification detrimentally impacts the performance and life of
the battery. Prior art solutions to the acid stratification problem
in batteries (e.g., lead acid batteries) include the use of `glass
mats` affixed to the separator. These glass mats, however,
significantly drive up the cost of the separator, have large pores
(thus, do not wick well), and in some cases do not lend themselves
to high speed manufacturing techniques (e.g., formation of
`pockets` and welding to the separator).
[0005] In some areas of the world, for example, Asia, lead/acid
batteries are sold as `dry charge` batteries. These dry charge
batteries are purchased without the water/acid included. The dry
charge battery has a longer shelf life. However, the user may not
be careful to fill the battery with uncontaminated water/acid. The
contaminated water/acid will lead to oxidation of the separator and
ultimately to battery failure. The contaminants in the water/acid
may be sourced from the water/acid containers, e.g., steel
drums.
[0006] Additionally, oxidation of the separator, e.g., separators
for lead/acid batteries, may reduce a battery's cycle life, and
thereby reduce the effective life of the battery. This oxidation
may arise from contaminants in the water or acid added to the `dry
charge` battery. Oxidation causes the embrittlement (measured by,
for example, loss of % elongation) of the separator which may lead
to partial or complete failure of the battery.
[0007] Contaminants typically originate from the water and/or the
sulfuric acid added to the battery, as well as from impurities in
the alloys and active materials that comprise the electrode plates,
and such contaminants may cause oxidation. Such contaminants
typically include the transition metals of the periodic table, for
example: chromium (Cr), manganese (Mn), titanium (Ti), copper (Cu),
and the like. Contaminant levels (Cr, Mn, and/or Ti) of greater
than about 2.0 ppm [2.0 mg/L] are not recommended. Cu contaminant
levels greater than 26 ppm [26 mg/L] are not recommended.
[0008] U.S. Pat. No. 5,221,587 discloses the use of latex in the
separator to prevent antimony (Sb) poisoning of the lead/acid
battery. Antimony is sourced from the lead plates (electrodes) of
the battery. Antimony is used as an alloying agent in the lead to
improve the manufacture of the plates and the cycle life of the
battery. Those of ordinary skill would not consider the teachings
of U.S. Pat. N0. 5,221,587 in arriving at a solution to the
separator oxidation problem mentioned above.
[0009] U.S. Pat. No. 6,242,127 discloses the use of cured, porous
rubber in a conventional polyolefin separator to improve the
electrochemical properties (antimony suppression) of the
separator.
[0010] There is a need for a new separator (e.g., for lead/acid
batteries) that addresses the foregoing acid stratification and
oxidation issues.
SUMMARY OF THE INVENTION
[0011] A battery separator for a lead acid battery addresses the
issues of acid stratification and/or separator oxidation arising
from contaminants. The separator includes a microporous membrane
and a diffusive mat affixed thereto. The diffusive mat has a three
hour wick of at least about 2.5 cm. The diffusive mat may be made
of synthetic fibers, glass fibers, natural fibers, and combinations
thereof. The diffusive mat may include silica. The separator may
include a rubber.
DESCRIPTION OF THE DRAWINGS
[0012] For the purpose of illustrating the invention, there is
shown in the drawings a form that is presently preferred; it being
understood, however, that this invention is not limited to the
precise arrangements and instrumentalities shown.
[0013] FIG. 1 is a graphical comparison of the inventive separator
(diffusive mat), INV, versus a separator with a conventional glass
mat, PA.
[0014] FIG. 2 is a graphical comparison of the inventive separator
(diffusive mat), INV, versus another separator with a conventional
glass mat, PA.
[0015] FIG. 3 is a graphical comparison of the inventive separator
(diffusive mat), INV, versus another separator with a conventional
glass mat, PA.
[0016] FIG. 4 is a graphical comparison of the inventive separator
(diffusive mat), INV, versus another separator with a conventional
glass mat, PA.
[0017] FIG. 5 is a graphical comparison of the inventive separator
(diffusive mat), INV, versus another separator with a conventional
glass mat, PA.
DESCRIPTION OF THE INVENTION
[0018] Lead/acid batteries are well known, see for example, Linden,
Handbook of Batteries, 2.sup.nd Edition, McGraw-Hill, Inc. New
York, N.Y. (1995) and/or Besenhard, Handbook of Battery Materials,
Wiley-VCH Verlag GmbH, Weinheim, Germany (1999), both incorporated
herein by reference. A separator may be used in any lead/acid
battery. In one embodiment, the lead/acid battery is a flood
lead/acid (FLA) battery, such as those used as inverter batteries,
enhanced flood batteries (EFB), ISS batteries, stationary
batteries, golf cart batteries, and the like.
[0019] In a first aspect of the invention, a diffusive mat (DM) is
included with a microporous membrane to improve battery performance
by, for example, imparting superior diffusion properties that
retard acid stratification, reducing antimony poisoning, improving
oxidation resistance, and improving micro short protection (arising
from dendrite growth). The laminate of the DM and microporous
membrane also protects against water loss by keeping the electrodes
from drying out through the action of electrolyte wicking, thereby
addressing the dry-out situation and protecting against acid
stratification by improved diffusion properties.
[0020] The diffusive mat (DM) is not a conventional glass mat.
Conventional glass mats are passive, and do not have diffusive or
wicking capability. The DM may have the ability to wick 25.times.
or more than the conventional wet or dry glass mat. The wicking
rate is inversely proportional to the acid stratification. The
conventional glass mat has a `three hour wick` of no greater than
0.6 cm, while the DM has a `three hour wick` of at least about 2.5
cm. Alternatively, the DM may have a `three hour wick` of at least
about 2.5 cm, or at least about 3.0 cm, or at least about 4.0 cm,
or in the range of about 2.5- about 10.0 cm, or in the range of
about 3.0- about 10.0 cm, or in the range of about 4.0- about 10.0
cm, or sub-combinations thereof.
[0021] The `three hour wick` test is performed by inserting a
standard sized piece of the material in a liquid (sulfuric acid
with a specific gravity of 1.280), waiting three hours, and
measuring the height of travel of the liquid up the material.
`Standard sized piece` means the same width and length, but
thickness may vary according to the natural thickness of the
material being tested, so that meaningful comparisons may be made.
For the `three hour wick` test, the sample has a width of 1 inch
and a length of at least 40 cm. The sample is marked every
centimeter up the vertical axis of the sample. The sample, held in
a clamp above the liquid, is inserted into the liquid to a depth of
2 cm. The wick height is measured, from the graduations on the
sample, at one, five, ten, and fifteen minutes and for a maximum
wick height after three hours. The DM may further include a
particulate filler, such as silica.
[0022] The DM may be laminated on to the microporous membrane in
any manner. The DM may be affixed to the microporous membrane by
welding or glue. The DM may be formed into pockets, sleeves,
leaves, of an `S` wrap. The DM may be a nonwoven or woven or
knitted fabric made of fibers. The DM may be made of glass fibers,
synthetic fibers, natural fibers, or combinations thereof. In one
embodiment, the DM may be made of glass fibers and synthetic
fibers. The DM has sufficient physical integrity to perform as a
positive active material (PAM) retention mat and prevents shedding
of PAM. The DM protects the separator from strong oxidizers (e.g.,
Cr, Mn, Ti). Several examples of suitable DM (INV) are set forth in
the TABLE below, along with a comparison to conventional glass mats
(Prior Art).
[0023] In use in the battery, the separator is placed in the
battery, so that the DM faces, or is in contact with the positive
electrode (or plate) of the battery. In one embodiment, the
separator may envelope the negative and/or positive plate(s). In
another embodiment, the separator may envelope the negative
plate(s).
TABLE-US-00001 TABLE Diffusive Mat (DM) Diffusive Mat (DM)
Synthetic fibers Glass fibers Conventional Glass Mat [INV] [INV]
[Prior Art] Composition Synthetic Coated Glass fiber Glass fiber
Synthetic wood Fine Glass retention mat.sup.1 retention mat fiber +
Pulp + Glass fiber + (wet-laid (dry-laid Category Units Silica
Silica fiber Silica process) process) Overall (mm) 0.305 0.373 0.3
0.215 0.5 mm 0.5 mm Puncture (N) 23.1 9.9 9.3 12.6 14.4 7.8
Tensile-MD (N/mm.sup.2) 8.7 5.3 9.5 23 4.5 1.0 Tensile-
(N/mm.sup.2) 6.8 3.3 5.4 11.8 4.3 2.8 CMD ER (10/20) (mohm- 41.7
87.6 12 15 2.7 2.3 cm.sup.2) Basis (gsm) 122.4 146.3 40 68 80.22
68.62 Weight 3 hour Wick (cm) 6 4.8 6.2 5.5 0.5 0 Stiffness (mN)
456 324 92 392 192 192 (MD) Stiffness (mN) 377 259 47 241 355 355
(CMD) .sup.1Commercially available from Johns-Manville as DURA
GLASS B-20 (20 mil thick standard glass mat).
[0024] Microporous membranes may be made from: sheets of polyolefin
(e.g., polyethylene, polypropylene, ultra high molecular weight
polyethylene (UHMWPE), and combinations thereof), polyvinyl
chloride (PVC), phenol-formaldehyde resins (including, for example,
cellulosic and/or synthetic fiber impregnated with
phenol-formaldehyde resins), crosslinked rubber, or nonwoven (e.g.,
inert fibers including cellulosic fibers or glass fibers). In one
embodiment, the microporous membrane may be made from polyethylene,
UHWMPE, or a combination of both and may include a particulate
filler, as is known. The microporous membrane may have a ribbed
profile. The ribs may be conventional, e.g., running in the machine
direction (MD) on the side to the positive electrode (e.g., to,
among other things, separate the separator from the positive
electrode, and form gas channels that allow gas to escape and
promotes mixing during over charge conditions), but the ribs may
also extend in the cross machine direction (CMD) on the side to the
negative electrode (to retard acid stratification).
[0025] In another aspect of the invention, rubber may be added to
the separator to address the oxidation issue arising from the
contaminants. Rubber, as used herein, refers to rubber latex, tire
crumb, and combinations thereof. In one embodiment, the rubber may
be un-cross-linked or uncured rubber. In another embodiment, the
rubber latex may be natural or synthetic rubber latex. In another
embodiment, the rubber may be natural rubber latex. In yet another
embodiment, the rubber may be tire crumb. Natural rubbers may
include, for example, any grade (e.g., latex grades), such as
ribbed smoked sheet, white and pale crepes, pure blanket crepes or
re-mills, thick brown crepes or ambers, and flat bark crepes.
Natural rubbers may include Hevea rubbers. Synthetic rubbers may
include, for example, methyl rubber, polybutadiene, chloropene
rubbers, and copolymer rubbers. Copolymer rubbers may include, for
example, styrene/butadiene rubbers, acrylonitrile/butadiene
rubbers, ethylene/propylene rubbers (ELM and PERM), and
ethylene/vinyl acetate rubbers. Other rubbers may include, for
example, butyl rubber, bromobutyl rubber, polyurethane rubber,
epichlorhydrin rubber, polysulphide rubber, chlorosulphonyl
polyethylene, polynorborene rubber, acrylate rubber, fluorinated
rubber, isoprene rubber, and silicone rubber. These rubbers may be
used alone or in various combinations.
[0026] In one embodiment, the rubber may be impregnated into the
microporous membrane. Impregnated, as used herein, means that the
rubber is incorporated into the body of the separator, and is not a
layer formed onto the separator. So, the rubber may be mixed or
blended into one or more the materials used to from the separator.
The rubber, for example the latex, is still chemically active
(i.e., uncured and/or uncross-linked) after extrusion. Thus, the
rubber is a component integral with, or distributed within, or
uniformly blended throughout, or intimately blended in the
materials of, the separator.
[0027] The rubber, as described above, may comprise any portion of
the microporous membrane. In one embodiment, the rubber may
comprise no more than about 12% by weight of the microporous
membrane when added to the formulation (i.e., the `by weight` of
the raw materials before extrusion). In another embodiment, the
rubber may comprise about 1-12% by weight of the microporous
membrane. In another embodiment, the rubber may comprise about
1.2-6% by weight of the microporous membrane. In yet another
embodiment, the rubber may comprise about 2-4% by weight of the
microporous membrane. In still another embodiment, the rubber may
comprise about 2.5-3.5% by weight of the microporous membrane. In
another embodiment, the rubber may comprise about 3% by weight of
the microporous membrane.
[0028] The microporous membrane may be made in any conventional
fashion. For example, in a PE microporous membrane, the rubber may
be mixed with the processing oil and mixed with the PE during
extrusion.
EXAMPLES
[0029] FIGS. (graphs) 1-5 are a comparison of the inventive
separators with the diffusive mat (DM) to separators with the
conventional glass mats. The separators are equivalent but one
separator has the DM and the other has the conventional glass mat.
The information presented in these graphs was generated using a
conventional Inverter Battery Simulation using a 12V150 Ah battery
(.apprxeq.100% depth of discharge, DoD) with the positive plate
enveloped (FIGS. 1-2) or the negative plate enveloped (FIGS. 3-5)
and with a discharge at 43 A for 1 hour and 54 minutes at 10.50V,
followed by recharge at 13.80V with a limit current of 15 A for 10
hours and 6 minutes.
[0030] The present invention may be embodied in other forms without
departing from the spirit and the essential attributes thereof,
and, accordingly, reference should be made to the appended claims,
rather than to the foregoing specification, as indicated the scope
of the invention.
* * * * *