Battery separator for lead acid batteries

Abstract

To provide a new or improved battery separator for a lead acid battery, the battery separator containing a carbon or mineral additive applied to the separator.SOLUTION: In an embodiment considered preferred, a battery separator may contain an engineered carbon material applied to the battery separator in order to modify the formation of sulfate crystals while reducing the deleterious effects of excessive gassing on the negative electrode itself. In one embodiment, a method of improving lead-acid energy storage performance of a lead-acid battery may include delivering carbon to the surface of a negative active material of a battery separator, and the carbon effectively improves charge acceptance to improve the life cycle performance of the lead-acid battery.SELECTED DRAWING: None

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of and priority to co-pending U.S. Provisional Patent Application Serial No. 61 / 988,386, filed May 5, 2014, which is incorporated herein by reference.

[0002] In accordance with at least selected embodiments, the present disclosure or invention is directed to new or improved battery separators, components, cells, systems, electrodes, and / or related methods of production and / or uses, battery separators with carbon or mineral additives for use in lead-acid batteries, carbon or mineral additives, and batteries containing such separators, or carbon and / or mineral additives. In at least some embodiments, the present disclosure is directed to new or improved lead-acid battery separators and / or methods of manufacture and / or uses thereof. In at least some selected embodiments, the present disclosure is directed to new or improved lead-acid battery separators with carbon or mineral additives, and / or methods for constructing lead-acid battery separators and batteries with such carbon or mineral additives to increase lead-acid energy storage performance, reduce lead content, and / or improve charge rate, reserve capacity, charge acceptance, cycle life, and / or the like. [Background technology]

[0003] Lead acid batteries have evolved over time as the demand for mobile power sources has grown. In certain service applications, flooded lead acid batteries may operate at a partial state of charge (PSoC), e.g., about 50-80% state of charge, unlike typical SLI (starting, lighting, and ignition) which is usually operated at 100% state of charge. For example, a hybrid electric vehicle (HEV) battery may operate at a PSoC of about 50-80% charge. In this way, the battery can undergo shallow charge / storage cycles and cannot be overcharged, where dissociation of water generates hydrogen and oxygen that mix with the layered acid within the cell.

[0004] Lead acid batteries are an excellent storage medium for energy, but one of the limitations may be the ability of the battery or battery chemistry to accept a fast charge, especially when the battery is at a high state of charge. In PSoC applications, this fast charging may come from the use of regenerative braking, which may recover much of the energy used to decelerate the vehicle. For this reason, the battery may typically operate at a low state of charge. In other applications, the battery may operate under very harsh usage conditions. In these instances, incomplete charging may be routine and difficult to avoid. For example, in developing regions of the world, the use of power inverter battery systems is common due to unstable power grids. In these instances, a battery charging from a discharged state may depend only on the availability of an unpredictable power grid.

[0005] Unlike many energy storage chemistries, in lead-acid batteries, the electrolyte, and likewise the active material in the electrode plates (e.g., PbO, etc.), participate in the electrochemical reaction. During the electrochemical process, lead sulfate is attracted to the negative electrode and precipitated in the form of seed crystals. Under typical fully charged operation, the crystals remain small and well-dispersed on the surface of the plate. The porosity of the electrode is only slightly altered. In PSoC operation, however, the formation of sulfate crystals is significantly less controlled. The result can be extensive sulfate crystal growth to the extent that the electrode porosity is compromised. At this stage, the plate is called "sulfated" since the crystal formation is irreversible. The ability of the negative electrode to accept a charge is dramatically reduced and may ultimately reach the end of the battery's life.

[0006] A battery separator is a component that divides or "separates" the negative and positive electrodes in a lead-acid battery cell. Battery separators have two primary functions. First, they must keep the positive electrode physically separated from the negative electrode to prevent the passage of any electronic current between the two electrodes. Second, they must allow ionic current between the positive and negative electrodes with minimal resistance. Battery separators can be made from many different materials, but these two opposing functions have been well met by battery separators made from porous non-conductors. Therefore, new battery separators and / or battery technologies are needed to meet and overcome the new challenges arising from current lead acid battery needs. Summary of the Invention

[0007] According to at least selected embodiments, the present invention addresses the above-mentioned needs, problems or issues, providing new or improved battery separators for lead-acid batteries. According to at least selected embodiments, the present disclosure or invention is directed to new or improved battery separators, components, batteries, systems, electrodes, and / or related methods of manufacture and / or uses, to battery separators with carbon and mineral additives for use in lead-acid batteries, to carbon or mineral additives, and to batteries including such separators, or carbon and / or mineral additives. In at least certain embodiments, the present disclosure relates to new or improved lead-acid battery separators and / or methods of manufacture thereof and / or uses thereof. In at least selected certain embodiments, the present disclosure is directed to new or improved lead-acid battery separators with carbon or mineral additives, and / or methods of constructing lead-acid battery separators and batteries with such carbon and / or mineral additives for increasing lead-acid energy storage performance, reducing lead content, improving charge rate, and / or improving reserve capacity, charge acceptance, cycle life, etc.

[0008] In at least selected embodiments, the battery separator may contain carbon or mineral additives that are applied to the separator and / or added to the battery. In a believed to be preferred embodiment, the battery separator may include engineered carbon materials that are applied to the battery separator to modify the formation of sulfate crystals while addressing the deleterious consequences of excessive gassing on the negative electrode itself. In one embodiment, a method for increasing the energy storage performance of a lead-acid battery includes delivering carbon to the negative electrode active material surface of the battery separator, where the carbon may increase charge acceptance and improve cycle life of the lead-acid battery.

[0009] In at least another selected embodiment, the improved battery separator and / or battery reduces lead content required, reduces separator electrical resistance (ER), extends cycle life, adds conductive material, increases cold cranking amperage (CCA), increases open circuit voltage (OCV), minimizes trapped gas, increases reserve capacity, improves capacitance characteristics, improves active material utilization, reduces energy consumption, reduces negative plate diffusion, and the like.

[0010] Additionally, active material retention is also an issue that can be addressed. In a PSoC scenario, there may be certain impediments that reduce the charge / discharge cycle efficiency of the battery. If the battery's ability to accept a charge is compromised, the cycle life of the battery may be prematurely shortened. The present disclosure may be an innovative approach to counteract undesirable changes to the charge acceptance characteristics of lead-acid batteries.

[0011] In lead-acid battery systems, the negative electrode is important for the charge acceptance phenomenon. The negative electrode may be considered the limiting component in an SLI battery in terms of cold cranking amperage (CCA). During discharge, the negative electrode may produce sulfuric acid electrolyte as the positive electrode consumes acid electrolyte. During the charge cycle, these roles may be reversed. Therefore, the negative electrode should constitute a porous structure that allows free adsorption of electrolyte during the charge cycle. Conversely, the negative electrode should not become impeding porosity so as to limit the release of electrolyte during the discharge cycle.

[0012] As mentioned above, during the electrochemical process, lead sulfate is attracted to the negative electrode and precipitates in the form of seed crystals. Under typical fully charged operation, the crystals remain small and well-dispersed on the plate surface. The porosity of the electrode changes slightly. However, in PSoC operation, the formation of sulfate crystals is not significantly controlled. As a result, sulfate crystal growth can become large to the extent that the porosity of the electrode is compromised. At this stage, the plate is called "sulfated" since the crystal formation is irreversible. The ability of the negative electrode to accept charge can decrease dramatically, eventually reaching the end of the battery's life. This is because, in order to accept a charge, the electrode should allow the incorporation of electrolyte into its porous structure. Thus, the improved battery separator according to the disclosure herein can play a fundamental role in improving the performance of lead-acid batteries and may improve the operation of, for example, flooded and VRLA (valve regulated lead acid) energy storage devices. [Brief description of the drawings]

[0013] For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. [Figure 1] FIG. 1 includes two photographic images, FIG. 1(a) shows a separator including a carbon coating according to one embodiment described herein, and FIG. 1(b) shows the separator without such a coating. [Diagram 2]FIG. 2 includes photographic images of three test lead acid batteries including a battery separator according to an embodiment described herein, and a control battery separator in a charge acceptance test. [Diagram 3] FIG. 3 is a plot of data from an example of a single cell charge acceptance after RC discharge after several weeks of cycling. [Figure 4] FIG. 4 is another plot of data from an example of single cell charge acceptance after RC discharge after several weeks of cycling. [Diagram 5] FIG. 5 is another plot of data from an example of single cell charge acceptance after RC discharge after several weeks of cycling. [Figure 6] FIG. 6 is yet another plot of data from an example of single cell charge acceptance after RC discharge after several weeks of cycling. [Figure 7] FIG. 7 is a bar graph based on the data from FIGS. 3-6 showing the reserve capacity comparison for the experimental and control cells. [Figure 8] FIG. 8 is another bar graph based on the data from FIGS. 3-6 showing a comparison of charge rates for the experimental and control cells. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] According to at least selected embodiments, the present invention utilizes engineered carbon materials (e.g., carbon black, graphite, activated carbon, etc.) applied to the battery separator (e.g., as a coating, surface treatment or layer, and / or provided on the separator material adjacent to the negative electrode plate) to modify the formation of sulfate crystals and address the deleterious consequences of excessive gassing on the negative electrode itself.

[0015] Engineered carbons such as carbon black, graphite and activated carbon have traditionally been used commercially as components of the negative electrode active material (NAM) in the negative electrode (or anode) itself used in lead-acid batteries. In such applications, engineered carbon materials are added to the paste or material used to form the negative electrode or anode. It has been found that these carbon additives can retard the sulfation effect (sulfate crystal growth on the anode) under PSoC conditions. For example, it has been found that the growth of sulfate crystals on the anode can be directly influenced by the available surface area (nucleation sites) within the plate. The increased surface area provided by engineered carbon materials applied to the anode ultimately has a smaller, less significant impact on the porosity of the negative electrode. , which may provide the driving force for the establishment of less stable sulfate crystals. In other words, in the prior art scenario, battery manufacturers have attempted to add high surface area engineered carbon materials to the negative electrode to reduce blockage of the pores of the negative electrode or anode, resulting in improved porosity and therefore improved efficiency of the negative electrode or anode.

[0016] However, there are problems with adding carbon materials to the negative electrode. Adding carbon can be expensive, as it is often costly. Additionally, battery manufacturers may find that the lifespan of a particular lead-acid battery is shortened due to the overall reduction in the amount of active material in the negative electrode (as the carbon material designed to prevent sulfate crystal growth constitutes "inactive material," thus removing an amount of "active" material that makes up the overall negative electrode).

[0017] Additionally, under typical conditions and / or reduced or partial state of charge (PSoC), the negative electrode will reach hydrogen over-potentials and thus produce gas, and gas evolution may be well understood as evidenced by numerous commercial battery designs to control gas. However, accelerated gas evolution may occur as high surface area carbon is introduced directly into the negative or anode NAM. Without wishing to be bound by theory, it is speculated that the presence of high surface area engineered carbon materials in the negative electrode creates additional sites for gas nucleation during charging of the lead acid battery. In this case, typical gas evolution may increase dramatically and gas may be liberated within the porous plate structure of the negative electrode. Thus, in an attempt to correct for sulfation (or reduce sulfate crystal growth), gas may be introduced into the interstitial regions of the electrode, resulting in poor electrolyte penetration, increased lattice corrosion, increased water consumption from the electrolyte (as gas is an insulator), reduced performance of the lead acid battery, or a combination of these. In this case, charge acceptance may be limited due to the blocking effect of trapped gas, and one problematic condition (growth of sulfate crystals on the anode) may be substituted for another (excessive gas generation in or to the anode).

[0018] Some battery manufacturers have attempted to solve the above problems by changing the surface area of ​​the carbon material added to the negative electrode or by reducing the amount of carbon material added to the negative electrode, but these solutions have not proven to be completely effective in improving the life cycle performance of the associated lead-acid battery.

[0019] Due to the above problems of adding engineered carbon materials to the negative active material of the anode, the inventors have discovered that it can be advantageous to add a carbon material, such as an engineered carbon material, to a battery separator where the separator is used in a lead acid battery. In some embodiments, the carbon material is added to the negative active material (NAM) surface of the battery separator, meaning the surface of the separator that contacts the negative electrode or anode.

[0020] In accordance with the invention described herein, the addition of one or more carbon materials to a battery separator means that the carbon materials are, by way of example only, not added to the monolithic negative electrode itself, but rather to the battery separator, such that, without limitation, the carbon materials no longer occupy space that could be better reserved for the negative electrode active material (NAM) of the electrode itself, and / or gassing effects in the negative electrode are dramatically reduced.

[0021] Adding engineered carbon materials as carbon materials, for example to battery separators for use in lead acid batteries, according to various embodiments described herein, may raise concerns among those skilled in the art that the same type of gassing may occur within the separator, however, the inventors have found that because the porosity of the separator tends to be greater than that of the negative electrode, the pores of the separator according to embodiments of the present invention still have enough space to adequately transport ions despite gassing.

[0022] In various embodiments of the present disclosure, a carbon material, such as an engineered carbon material, is added to the negative electrode active material (NAM) surface of the battery separator. This is because the negative electrode is where sulfate crystal growth and gassing typically occurs. It has been found that the battery separator according to the present invention results in improved overall performance of the lead acid battery, since the power of the battery is not sacrificed by the use of a carbon material as part of the negative electrode itself. Such battery improvements may be manifested, for example, in improved levels of cold cranking amperage (CCA) compared to batteries using conventional separators without the addition of the carbon material described herein.

[0023] In some embodiments of the invention, the battery separator may be made of a polyolefin, such as polyethylene, polypropylene, combinations thereof, and the like. In various embodiments of the invention, the battery separator may be laminated to another layer, including, for example, a glass layer, a polymer layer (such as polyester), a nonwoven layer, and the like. In such embodiments, for example, a laminate including a polyolefin battery separator and another layer, such as a nonwoven layer, is intimately bonded to the negative electrode, and when gassing occurs in a lead-acid battery, the gas will enter more of the pores of the nonwoven layer and thus will not be primarily present in either the negative electrode or the pores of the polyolefin battery separator. This may result in improved overall performance of a lead-acid battery incorporating such a laminated or composite separator. Overall, the addition of the carbon additive and / or mineral additive described herein to the negative electrode active material surface of a battery separator for use in a lead-acid battery results in modification of sulfate crystal growth or formation within the battery system, reduction of excess gassing in the system, increased charge acceptance of the lead-acid battery, and / or improved cycle life and / or performance of the lead-acid battery.

[0024] Carbon materials suitable for use in battery separators according to the present invention include, but are not limited to: graphite Activated carbon Carbon Black Graphene and related structural analogues Dendritic forms of carbon Nanocarbon materials derived from various manufacturing methods Highly structured carbonaceous materials (fullerenes, buckyballs, etc.) Carbon monolithic and carbon multicomponent sol-gel materials, and Combinations of the above may include.

[0025] The desired surface area (BET method) of the carbon forms that may be used with the embodiments discussed herein is greater than 10 m 2 / g and / or 500m 2 / g and / or 1500m 2 / g and / or 3000m 2 / g and / or 5000m 2 For example, in some embodiments, the surface area of ​​the carbon (BET method) is from 10 to 5000 m 2 / g, and / or 500-3000m 2 / g, and / or 1500-3000m 2 / g etc.

[0026] In various embodiments, the additive material, such as a carbon additive, is applied to the battery separator in a coating solution, paste, or slurry. For example, but not limited to, carbon black (fine powder) in a desired concentration in an aqueous slurry (or paste or dispersion), 1-80% w / w, and / or 2-60% w / w, and / or 2-30% w / w of carbon in the total solution (often the remainder is water and / or water and one or more (which may be some mixture with surfactants and / or additives).

[0027] The slurry or coating solution may be aqueous and may include a surfactant, such as an ionic or non-ionic surfactant. Such a surfactant may, for example, allow the electrolyte to more easily wet the pores of a given separator. This may lead to a higher CCA rating for a given battery, which may be desirable in various applications. An example of a surfactant is sodium dihexyl sulfosuccinate. However, any number of surfactants may be used in accordance with the embodiments described herein. Surfactant The antibacterial agent may comprise from about 0.5 to about 10% by weight of a given coating solution / slurry / paste.

[0028] The porosity of the separator allows for rapid adsorption of the carbon dispersion on the surface with negligible penetration of the carbon particles into the pore structure of the separator. The separator may be coated in a number of ways including gravure roll, reverse gravure, slot die method, air spray method, dip coating method, paint brush, sponge application, etc.

[0029] The thickness of the carbon coating or layer can be tailored to meet the design parameters of the electrode plate spacing in the battery. In general, the thickness of the coating can be tailored from sub-microns to hundreds of microns.

[0030] Methods for drying the coated separator can include many forms of energy to drive off excess water, such as microwave, forced air oven, convection oven, infrared energy, solvent evaporation drying, azeotropic drying, etc. The contact time required to dry the separator can vary depending on the method, coating thickness, composition and separator surface pattern and thermal properties. Benefits achieved by utilizing the elements described herein as part of this disclosure include, but are not limited to:

[0031] Substituting additives with active materials is beneficial when it is feasible for these additives to be located in the immediate vicinity, excluding containment within the active material of the electrode. The present disclosure proposes this scenario by deploying additives from an alternative substrate. The disclosure discusses a preferred means of implementing such deployment, for example, via the addition of carbon additives to the battery separator, such as a polyethylene (PE) separator substrate, as opposed to such additives being part of the negative electrode. This benefit can be achieved by replacing the capacity previously required within the active material with additional active material. In essence, the battery can be made more robust through a simple increase in the density of the active material by the removal of the previously contained additive. Incorporation of said additives onto adjacent or peripheral substrates, such as separators, wicking retention mats, spacer mats, and other woven and / or nonwoven materials made of synthetic or cellulosic fibers, can achieve these and other benefits, and are discussed herein.

[0032] By way of example, and not limitation thereto, the gradual removal of the carbon additive from the NAM in order to utilize the negative electrode surface of the separator as a carbon additive platform may provide the following advantages: 1. Removing carbon from NAMs reduces the amount of additional active material, increases manufacturing complexity, and This may allow costs to be reduced. 2. It can provide surface area for nucleation of sulfate crystals without a corresponding loss in porosity of the negative plate, especially in PSoC operation. The separator function cannot be altered. 3. Gas evolution at the plates can proceed normally without excessive nucleation within the pores of the plates. In the case of flooded LA systems, gas can nucleate on the separator coating where buoyancy forces can carry the gas to the surface of the electrolyte.

[0033] Perhaps for optimal results, the separator may be coated with carbon on the side that directly contacts the negative plate (e.g., the NAM side of the separator). In some cases, there is sufficient pressure between the plate and the separator to maintain contact between the plate, coating, and separator. The carbon additive may be used on any profile or topology present on the negative surface of the separator (e.g., ribs, mini-ribs, cross-ribs, land areas for later encasement, etc.). By way of example only, various separators suitable for use herein include ribs that may maintain distance or spacing between the plates, hold the plates apart, and / or maintain distance or spacing between the separator backweb and the plates. For example, in FIG. 1(b), the ribs are located on the inside of a pocket or envelope-shaped separator. In some examples, the separator includes cross-ribs, and such cross-ribs may be located on the surface of the separator that contacts the anode or negative electrode or plate.

[0034] In some embodiments, the binder may be part of the carbon-containing coating, slurry, paste, or solution and is added to the separator to improve the separator. The binder composition may be functional or inert. Latex, liquid rubber, starch solutions, acrylonitrile, acrylates, their derivatives, polyolefins, etc. are examples of binders. In some embodiments, the binder is added to the separator separately and is not part of the carbon-containing coating, slurry, paste, or solution.

[0035] Alternatively, the separator may include a layer of carbon selected from a list of suitable carbon options. This layer may be added to the separator as a separate layer, preferably on the side intended to face the plate surface of the negative electrode, or the carbon may be embedded in the negative electrode surface of the separator by any number of means, including coextrusion, or mechanically embedding the carbon on the surface during an extrusion / calendering / cooling operation. Although not a preferred separator, these application methods may also be useful for reinforcing microporous separators produced via techniques that are not in widespread use, such as rubber or PVC.

[0036] The application of carbon is not limited to the type of separator, but may be accomplished for delivery by any number of means so long as it can make intimate contact with the surface of the negative plate active material, thus generally avoiding forming a direct conductive path between the positive and negative plates. For example, a multi-layer or composite separator may have a carbon-containing conductive layer adjacent to the negative plate and a second non-conductive layer adjacent to the positive plate.

[0037] Carbon may be dispersed throughout the volume of the separator if desired, and in some cases, depending on the carbon loading level and density on the positive plate, a non-woven mat between the carbon-containing separator and the positive electrode is desired to prevent unwanted self-discharge.

[0038] In some types of lead acid batteries or in certain applications, it may prove useful to use a nonwoven mat alone or in conjunction with a conventional separator such as a polyethylene separator. Carbon may be applied to or as a component of the nonwoven fabric.

[0039] The carbon additives described herein may be applied in a variety of ways, for example, with a paste paper or mat applied directly to the surface of the battery plate during either plate manufacture or assembly. The carbon may be applied with the paste paper, as a component or coating of the paste paper, laminate or other structure intended to also function as a paste adhesive unit. This material may be used as a paste paper during the manufacture of lead plates, laminated to a separator, assembled as a layer in addition to the separator, or even used as a complete separator depending on the lead acid battery design.

[0040] As a simple way to incorporate activated carbon properties into a lead acid battery, carbon can simply be added to the inside of a pouch in the form of bulk material when a common envelope of separator is used to encase the individual plates. By adding a pouch around the negative plate and incorporating the carbon within the pouch, the carbon is contained and in intimate contact with the active material contained on the surface of the negative plate. As an example, the negative plate can be coated in a mixture of carbon and oil or other binder as an oxidation inhibitor and by applying the carbon directly to the surface of the negative active material, for example.

[0041] Plates intended for use in such battery designs can be contacted directly by exposure to a suspension or colloidal mixture of carbon and similar additives that provides the desired results, or alternatively, by spraying the carbon or electrostatic powder coating methods on the plates as an integral part of the manufacturing process.

[0042] The disclosure presented herein may provide the result that carbon does not have to be a constituent of the negative electrode active material to provide a benefit. Indeed, it has been found that applying such carbon as part or all of an added layer adjacent to, embedded in, or directly on the outer surface of the paste may provide the benefit of improved charge acceptance and cycle life while reducing the negative effects associated with increasing the carbon composition of the negative electrode active material. This may provide the benefit of additional conductivity that prevents isolation of lead sulfate discharge products at or near the surface of the negative electrode active material.

[0043] Various embodiments herein have found that a separator coated with a solution or coating or paste containing a related carbon material can exhibit improved properties compared to an uncoated separator without the coating of a solution / coating / paste of a related carbon material.Furthermore, various embodiments herein have found that the related carbon material can be made into a free-standing porous carbon sheet and inserted into or next to a separator for use with a lead-acid battery.In various examples, such carbon sheets can contain more than 50% carbon material, and / or more than 70% carbon material, and / or more than 80% carbon material, and / or more than 85% carbon material.In one particular embodiment, a carbon sheet containing about 87% carbon can be used with the separator described herein.

[0044] In other words, in various embodiments described herein, rather than putting the carbon material in the negative active material of the battery anode, the carbon material is placed elsewhere in the battery system, for example to produce unexpected benefits. Such carbon material may be placed, in accordance with various embodiments herein, on the separator, next to the separator, inside a pocket or envelope of the separator, as a coating, as a sheet, as a carbon fill inside a pocket of the separator envelope (meaning that loose carbon may be inside the pocket or envelope around the plate therein), etc.

[0045] [Example] Example 1 Application of carbon to polyethylene lead-acid battery separators A coating solution, slurry or paste was prepared and then applied to the negative electrode surface of the separator as detailed below. Figure 1(b) shows a battery separator for use in lead acid batteries, e.g., a polyethylene separator. In this particular embodiment shown in Figure 1(b), the separator has a cross-rib shape (meaning it has a main rib and a cross rib), has a cut edge on the left side open for insertion of a battery plate, a folded end on the right side, and top and bottom ends closed by crimping or sealing or the like. The ribs may provide distance or separation for the battery separator. However, many shapes of separators may be used in the embodiments herein. In Figure 1(b), the polyethylene separator is uncoated.

[0046] 1(a) shows a similar polyethylene separator for use in a lead acid battery coated with a coating of carbon black according to an embodiment described herein, prepared by incorporating 2-3 wt. % of a surfactant, here sodium dihexyl sulfosuccinate (available under the tradename Aerosol MA-80 from Cytec Industries Inc., Woodland Park, NJ). Carbon black, available in finely divided powder form from Cabot Carbon Corporation under the tradename PBX51 carbon black (having a surface area of ​​approximately 1850 m2 / g), was dispersed in the aqueous surfactant solution.

[0047] FIG. 2 shows three separate cells containing various separators suitable for use in lead-acid batteries that were cycled and tested. In the cell in the portion of FIG. 2 labeled FIG. 2(a), the separator is the carbon coated separator depicted in FIG. 1(a). In the cell in the portion of FIG. 2 labeled FIG. 2(b), the separator is a carbon coated separator commercially available from Daramic, Inc. as the Duralife Separator. In the cell in the portion of Figure 2 labeled 2(c), the separator is the "control" separator for the various experiments conducted herein, a polyethylene separator that does not contain a carbon coating (but does contain MA-80 surfactant). As shown in Figure 2, multiple envelope-style or pocket-style separators are included in the various cells.

[0048] To measure the performance of the batteries containing the separators (specifically the carbon coated separator shown in FIG. 2(a) versus the control separator shown in FIG. 2(c)), the cells were cycled for several weeks and then subjected to various tests. The data contained in FIG. 3 and FIG. 6 show the single cell charge acceptance after several weeks of cycling followed by a reserve capacity ("RC") discharge. FIG. 6 includes data from four replicate test sets of the experimental cell and separator (Carbon AD) and the control cell and separator (Control AD), whereas FIG. 3 simply illustrates one of the data sets for Carbon C and Control C. The y-axis units of FIG. 3 and FIG. 6, amp * time, allow the data to be viewed in a more cumulative format. Also, the carbon coated separator used in the cells to obtain the Carbon AD results performed better in terms of single cell charge acceptance compared to the uncoated Control AD ​​separator (see FIG. 3 and FIG. 6).

[0049] The data contained in Figures 4 and 5 show the charge acceptance of a single cell after RC discharge after several weeks of cycling. Figure 5 contains data from four replicate sets of experimental cells and separators (Carbon AD) and control cells and separators (Control AD), while Figure 4 simply illustrates one of the data sets for Carbon C and Control C. Figures 4 and 5 show the charge acceptance of a single cell after RC discharge after several weeks of cycling. The y-axis units allow you to view the data in a more instantaneous format. The carbon-coated separator used in the cells to obtain the Carbon AD results is Charge acceptance of a single cell compared to a control AD ​​separator that was not (See Figures 4 and 5).

[0050] More test data is reflected in Figure 7, which shows that the carbon-coated battery separator improved the reserve capacity of the cell after various cycling periods. Thus, it may be important for the carbon-coated separator to provide charge acceptance to the cell, increase reserve capacity, and retain these properties through cycling.

[0051] Similarly, FIG. 8 presents the results of various tests of the experimental and control cells described above, showing the charge acceptance after various cycling periods for cells made with the experimental carbon-coated separators and the control uncoated separators. In FIG. 8, more than half of the energy in the battery has been removed. The charge acceptance of the cells improved over time, even after sustained periods of continuous cycling (as seen by the 50% DOD or depth of discharge designation). The charge acceptance characteristics improved appreciably, and the cells with carbon coated separators were better able to accept a charge.

[0052] According to at least selected embodiments, aspects or objectives, the present disclosure or invention is directed to new or improved battery separators, components, cells, systems, electrodes and / or related methods of manufacture and / or uses, battery separators having carbon and mineral additives for use in lead acid batteries, carbon or mineral additives, and batteries including such separators or carbon and / or mineral additives. In at least certain embodiments, the present disclosure relates to new or improved lead acid battery separators, cells, systems, and / or methods of manufacture and / or uses thereof. In at least certain selected embodiments, the present disclosure relates to new or improved lead acid battery separators, cells, systems, and / or methods of manufacture thereof and / or uses thereof. The present invention is directed to new or improved lead acid battery separators and / or methods of constructing lead acid battery separators and batteries having such carbon and / or mineral additives to improve reserve capacity, charge acceptance, cycle life, and the like.

[0053] In at least another selected embodiment, the improved battery separator and / or battery reduces required lead content, reduces separator electrical resistance (ER), extends cycle life, adds conductive material, increases cold cranking amperage (CCA) efficiency, increases open circuit voltage (OCV), minimizes trapped gas, increases reserve capacity, improves capacitance characteristics, improves active material utilization, reduces energy consumption, reduces negative plate diffusion, and the like.

[0054] In at least other selected embodiments, at least one battery separator for a lead acid battery is provided that improves the electrical storage performance of the lead acid battery. 13. A battery separator for a lead acid battery as shown and described herein. The battery separator for the lead acid battery is The battery separator includes an additive applied to the battery separator to improve lead acid performance of the lead acid battery.The battery separator above, wherein the additive is a carbon or mineral additive applied to the separator.The battery separator above, wherein the additive is applied to the battery separator and includes an engineered carbon material that modifies sulfate crystal formation while reducing the deleterious consequences of excessive gassing at the negative electrode.

[0055] The battery separator above, wherein said engineered carbon material is selected from the group consisting of carbon black, graphite, activated carbon, and combinations thereof. The battery separator as described above, wherein said additive is applied to a surface of the negative electrode active material (NAM) of the battery separator. The battery separator as described above, wherein said additive retards sulfation effects under partial state of charge (PSoC) conditions, The growth of sulfate crystals is directly influenced by the available surface area (nucleation sites) within the battery plates. The increased surface area has less impact on the porosity of the negative electrode and provides a driving force for the establishment of smaller, less stable crystals; Under typical PSoC conditions, when the electrodes reach a hydrogen overpotential, they produce gas, When high surface area carbon was directly introduced into the NAM, the promotion of both gas and sulfate nucleation occurred, dramatically increasing typical gas evolution, and the gas was liberated within the porous plate structure, Gases are introduced into the interstitial regions of the electrodes, resulting in poor electrolyte penetration, increased grid corrosion, increased water consumption from the electrolyte, increased ionic resistance, etc., and combinations thereof; Charge acceptance may be limited by the blocking effect of trapped gas, and / or A combination of these occurs.

[0056] The battery separator described above, in which engineered carbon materials include graphite, activated carbon, carbon black, graphene and related structural analogues, dendritic forms of carbon, nanocarbon materials derived from various manufacturing methods, highly structured carbonaceous materials (such as fullerenes and buckyballs), carbon monolithic and carbon multi-component sol-gel materials, the like, and combinations thereof.

[0057] The battery separator above, wherein the additive has a surface area selected from the group consisting of 10 to 5000 square meters / g, 500 to 1500 square meters / g, and 1500 to 3000 square meters / g. The battery separator as above, wherein the additive is applied to the negative electrode surface of the separator. The additive is 0.5% by weight to 10% by weight of a surfactant. Carbon black in the form of a finely ground powder dispersed in an aqueous surfactant solution; The battery separator as described above. The battery separator wherein the surfactant is an ionic surfactant. The above battery separator, wherein the ionic surfactant is sodium dihexylsulfosuccinate at a concentration of 2 to 3% by weight. The above battery separator, wherein the carbon black has a concentration selected from the group consisting of 1-80% weight / weight, 2-60% weight / weight, and 2-30% weight / weight.

[0058] The above battery separator, wherein the porosity of the separator allows for rapid adsorption of the carbon dispersion on the surface with negligible penetration of the carbon particles into the pore structure of the separator. The battery separator above, wherein the separator may be coated by a method selected from the group consisting of gravure roller, reverse gravure, slot die method, air spray method, dip coating method, paint brush, sponge coating, similar methods and combinations thereof. The battery separator above, wherein the thickness of the carbon coating can be adjusted to fit the design parameters of the electrode plate spacing in the battery, thereby allowing the thickness of the coating to be adjusted from sub-microns to hundreds of microns.

[0059] The above battery separator, wherein the method of drying the coated separator may include any drying method for driving off excess water. The battery separator wherein the drying method is selected from the group consisting of microwave, forced air oven, convection oven, infrared energy, solvent evaporation drying (azeotropic drying), similar methods, and combinations thereof.

[0060] The above battery separator, which chooses to utilize the surface of the negative electrode of the separator as a platform for the carbon additive and gradually removes the carbon additive from the NAM, provides the following advantages: Removing carbon from NAMs can provide additional active material or reduce manufacturing complexity and cost; The separator function is unchanged, particularly in pSOC operation, providing surface area for sulfate crystal nucleation without a corresponding loss in porosity of the negative plate; Gassing of the plates normally proceeds without excessive nucleation within the plate pores, where the gas nucleates on the separator coating and, in the case of flooded lead-acid systems, is carried to the electrolyte surface by buoyancy forces; or A combination of them.

[0061] The battery separator as above, wherein the separator is coated with carbon on the side that is in direct contact with the negative electrode plate (NAM). To maintain contact between the plate, coating and separator, The battery separator, wherein sufficient pressure exists between the battery separator and the battery. The battery separator described above, wherein the carbon additive may be used in any profile or topological feature present on the negative electrode surface of the separator (e.g., ribs, mini-ribs, cross-ribs, land areas for later wrapping, etc.). The battery separator above, wherein said additive is applied to the separator with a binder. The battery separator above, wherein the binder composition can be functional or inert. The battery separator above, wherein the binder is latex, liquid rubber, starch solution, acrylonitrile, acrylic esters and their derivatives, and the like, or a combination thereof. The battery separator, wherein the additive is a layer added as a separate layer to the separator. The battery separator above, wherein an additive layer is added to the side intended to face the negative plate surface. The battery separator as above, wherein the additive is embedded in the separator. The battery separator above, wherein the additive is embedded in the separator on a surface facing the negative electrode. The battery separator as above, wherein the additive is embedded throughout the separator. The battery separator above, wherein the additive is embedded in the separator by an embedding process, where the additive is co-extruded or embedded mechanically onto the surface during the extrusion / calendering / cooling operation. The battery separator further includes a nonwoven mat between the carbon-containing separator and the positive electrode to prevent unwanted self-discharge.

[0062] The battery separator or improved battery or electrode as described above, wherein the additive is applied using an adhesive paper or mat that is applied directly to the surface of the battery plate during manufacture or assembly of the plate, and the additive is applied by the adhesive paper as a component, or other structure that is also intended to function as a coating, laminate, or paste attachment for the adhesive paper, whereby this material can be used as an adhesive paper during manufacture of the lead acid plate, laminated to the separator, assembled as a layer in addition to the separator, or even used as a complete separator depending on the lead acid battery design.

[0063] The battery separator as described above, in which the additive is added in the form of bulk material to the inside of the pouch when a common envelope of separator is used to encase the individual plates, and the carbon is contained by adding a pouch around the negative plate and placing the carbon within the pouch; It is in intimate contact with the active material contained on the surface of the negative plate.

[0064] Alternatively, carbon may be applied locally as an integral part of the manufacturing process to the plates by spraying or electrostatic powder coating, with the battery separator or improved battery or electrode being directly contacted by exposure to a suspension or colloidal mixture of the carbon and similar additives herein, intended for use in such battery designs, which will produce the desired results.

[0065] The battery separator further comprises a microporous membrane in combination with a synthetic nonwoven fabric impregnated with a mineral filler. The battery separator as above, wherein said membrane is a polymer filled membrane. The battery separator above, wherein the polymer is a polyolefin. The battery separator as above, wherein said filler is a silica-based material. The battery separator above, wherein said membrane has ribs. The battery separator above, wherein said ribs are ribs running in the machine direction and / or cross machine direction. In a battery, the improvement comprising the battery separator and / or electrode described above.

[0066] An additive for use in a composite battery separator for a lead acid battery, such as an ISS, HEV or EFB battery, comprising an additive applied to the battery separator to enhance lead acid storage performance. A method for improving the lead acid storage performance of a lead acid battery. As shown and described herein, a method for improving the lead acid storage performance of a lead acid battery. 1. A method for improving lead acid storage performance of a lead acid battery, the method comprising the step of providing a battery separator with an additive applied to the battery. The above method includes providing carbon on the surface of the negative electrode active material of the battery separator, where the carbon can most efficiently enhance the charging performance and improve the life cycle performance of the lead-acid battery. A reduced lead content battery as shown or described herein. A new or improved battery separator for a battery having reduced lead content as shown or described herein.

[0067] According to other embodiments, the amount of lead currently required to manufacture flooded SLI batteries can be reduced, for example, by at least one of the following: Reducing the lead content of SLI batteries while retaining or improving existing benchmarked performance attributes. Separator electrical resistance reduced by 25% The separator acts to limit resistance within the energy storage device. A substantial reduction in separator resistance (e.g., 20-30%) is a means to improve cold cranking amperage (CCA) efficiency. In lead acid SLI battery systems, the CCA rating is important for engine starting capability, especially in extreme temperatures. The CCA rating is a well-established industry standard that can be a key to customer acceptance and selection of aftermarket and OEM batteries. Because industry expectations for CCA exist and low-resistance separators serve to improve CCA, three options become available to battery manufacturers: The CCA rating can be held constant by removing active material from the electrode plates and / or removing electrode plates from the battery design. The elimination of lead through the active material and / or plates is particularly attractive because performance is maintained while manufacturing costs are significantly reduced. Certain battery systems operating in harsh conditions may have an increased CCA rating. CCA ratings may be increased as a means to seek greater consumer acceptance.

[0068] Alternative Current Distribution US Patent Application No. 2008 / 0076028A1 describes the application of an oxidation-resistant conductive metal to the ribs of a lead-acid battery separator, which are in direct contact with the active material attached to the electrode plates, enhancing utilization of the active material and reducing oxidation corrosion of the lead structure, including the electrode plates themselves. In the aforementioned applications, the results achieved were a 20-30% increase in the cycle life of the battery. The new approach utilizes the cited concept of current distribution by deposition of conductive carbonaceous compounds and alternative conductive materials onto separator ribs and, alternatively, onto cellulosic materials known in the art as platforms for active material on the electrode. In this case, the current is distributed in a manner that favors cycle life and suppresses the positive grid corrosion mechanism. In many cases, as little as 30% of the active material applied to the electrodes is actually utilized. In these cases, improving current distribution through the conductive paste paper or conductive rib surfaces offers the option to remove substantial amounts of positive and negative active material from the electrode plates, saving manufacturing costs while maintaining or improving performance relative to unmodified SLI batteries. In addition, the lead grids that comprise the electrodes can be redesigned to remove lead that is no longer needed for the current distribution function of the separator or alternative conductor base (paste paper).

[0069] Approach to negative plate diffusion The negative electrode is the limiting component in an SLI battery in terms of cold cranking amperage (CCA). During discharge, the positive electrode consumes acid electrolyte and the negative electrode produces sulfuric acid electrolyte. During the charge cycle, these roles are reversed. Modifying the pore structure of the separator to increase the diffusional flow of electrolyte to the negative electrode provides a means to increase CCA efficiency, which in turn provides a similar set of benefits to consumers and manufacturers, as noted in the "High Porosity / Low Electrical Resistance" section above. The CCA rating can be held constant while removing active material from the electrode plates or removing electrode plates from the battery design. Removal of lead through the active material and / or plates is particularly preferred as it maintains performance while significantly reducing manufacturing costs. For certain battery systems operating in harsh conditions, the CCA rating may be increased. CCA ratings may be raised as a means to seek greater consumer acceptance.

[0070] High OCV and Shallow Discharge Separator The improved separators are designed to provide a higher open circuit voltage (OCV) for shallow discharge profiles. This attribute reduces the voltage drop of the battery over a longer period of time. The CCA associated with such batteries is substantially enhanced relative to that of batteries with conventional separators. Strengthening the CCA will benefit both consumers (through performance) and manufacturers (through cost savings). These benefits have been previously explained and specifically include: The CCA rating can be held constant while removing active material from the electrode plates or while removing electrode plates from the battery design. The elimination of lead through the active material and / or plates is particularly desirable as it maintains performance and significantly reduces manufacturing costs. Certain battery systems operating in extreme conditions may have an increased CCA rating. CCA ratings may be increased as a means to seek greater consumer acceptance.

[0071] Minimizing trapped gas Trapped gas in the battery leads to high resistance, reduced CCA, and reduced reserve capacity. The separator surface profile, determined by the rib design, is one of the key ways to reduce gas entrapment in the region between the electrodes and the separator. Another concept that works throughout the battery is the strategic placement of materials with high random surface area (anisotropic) within the cell compartment to allow access to the bulk electrolyte itself. Electrolytes, as bulk fluids, by nature contain dissolved gases. The concentration of dissolved gases naturally varies with temperature of the electrolyte due to the solubility characteristics. It is important to take the whole battery into consideration when reducing dissolved or trapped gases. The electrolyte resistance changes as gas dissolution increases, and therefore it is advantageous to maintain a constant or low level of dissolved or trapped gas under all operating conditions. Since the magnitude of the effect of dissolved / trapped gases is known for important properties such as CCA and reserve capacity, this region reveals the potential for optimizing the active materials through reduction, in this case the means to reduce the active materials is the elimination of resistance within the battery system.

[0072] Separator with capacitance properties Ultracapacitors or supercapacitors are known and in the simplest sense, these The design of the capacitor allows for the storage of charge and rapid release of the stored charge. These devices are not batteries because they cannot actually sustain the chemical reactions that lead to extended operation without an external charging source. However, the capacitor-battery hybrid concept may offer performance and manufacturing advantages. Forming a capacitance grade (high surface area) carbonaceous layer on the separator side in contact with the cathode can be accomplished by several deposition means. The cathode is chosen as the contact surface because it is this electrode that exhibits the magnitude of the CCA. As the battery operates under nominal conditions, the capacitance grade carbonaceous material builds up a surface-resident charge density. During a heavy discharge, such as during engine ignition, this charge is transferred to the negative electrode, providing a "boost" to the reaction kinetics. In the aforementioned applications, the active materials are utilized in a more efficient manner that facilitates their removal from the battery, thus providing significant benefits to the manufacturer through cost reduction.

[0073] More possible benefits are: Shorter formation time High utilization of fixed assets Low energy consumption Alternative Current Collectors Increased spare capacity Minimizing trapped gas Increased spare capacity Improved charging acceptance Addressing cathode plate diffusion Improved charging acceptance

[0074] In accordance with at least selected embodiments, aspects, or objectives, improved battery separators, batteries, systems, electrodes, and / or methods of manufacture, and / or uses are provided. In accordance with at least certain embodiments, aspects, or objectives, the present disclosure or invention is directed to lead-acid batteries (flooded, reinforced flooded (EFB), gel, VRLA, and / or the like) and / or improved batteries including such separators.

[0075] In accordance with at least certain embodiments, aspects, or objectives, a new or improved battery separator for a lead-acid battery is provided that includes a carbon or mineral additive applied to the separator. In a possible preferred embodiment, the battery separator may include an engineered carbon material applied to the battery separator to modify sulfate crystal formation while reducing the deleterious consequences of excessive gassing on the negative electrode itself. In one embodiment, a method for improving lead acid storage performance of a lead acid battery may include delivering carbon to a negative electrode active material surface of the battery separator, where the carbon may effectively enhance charge acceptance and improve cycle life of the lead acid battery.

[0076] The present invention may be embodied in other forms without departing from its spirit and essential characteristics, and therefore, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the invention. In addition, the present invention illustratively disclosed herein may suitably be practiced in the absence of any element not specifically disclosed herein. Many other modifications and variations of the invention will be possible to those skilled in the art in light of the teachings herein, and it is therefore understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.

Claims

1. A battery separator for a lead acid battery comprising a porous membrane made of polyolefin laminated to a nonwoven fabric layer, the nonwoven layer comprises silica; a coating comprising a binder and a carbon additive is provided on at least one surface of the lead acid battery separator; 2. A battery separator for a lead-acid battery, the battery separator being disposed such that, when disposed in the lead-acid battery having an active material on an electrode surface, the coating faces a surface of the negative electrode active material.

2. 10. The battery separator for a lead acid battery of claim 1, wherein said coating further comprises a surfactant.

3. 3. The battery separator for a lead acid battery of claim 2, wherein said surfactant comprises a non-ionic surfactant or an ionic surfactant.

4. 10. The battery separator for a lead acid battery of claim 1, wherein said coating is a water soluble coating.

5. 10. The battery separator for a lead acid battery of claim 1, wherein said binder is latex, liquid rubber, starch solution, acrylonitrile, acrylic esters and their derivatives, or combinations thereof.

6. 10. The battery separator for a lead acid battery of claim 1, wherein said lead acid battery is a valve regulated lead acid battery.

7. 10. The battery separator for a lead acid battery of claim 1, wherein said lead acid battery is a flooded lead acid battery.

8. 10. The battery separator for a lead acid battery according to claim 1, wherein said lead acid battery operates under a partial state of charge (PSOC) of 50-80%.

9. 10. The battery separator for a lead acid battery of claim 1, comprising a free-standing porous engineered carbon sheet, said engineered carbon having a surface area of ​​1500-3000 m 2 / g.

10. 10. The battery separator for a lead acid battery of claim 9, wherein said free-standing porous engineered carbon sheet is interposed in or adjacent to a separator.

11. 10. The battery separator for a lead acid battery of claim 9, wherein said free-standing porous engineered carbon sheet comprises 50% or more carbon.

12. 10. The battery separator for a lead acid battery of claim 9, wherein said free-standing porous engineered carbon sheet comprises 70% or more carbon.

13. 10. The battery separator for a lead acid battery according to claim 9, wherein said lead acid battery operates under a partial state of charge (PSOC) of 50-80%.

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