WO2017062053A1

WO2017062053A1 - Flooded acid battery with improved performance, improved battery separators, and related methods

Info

Publication number: WO2017062053A1
Application number: PCT/US2016/012805
Authority: WO
Inventors: Eric H. Miller; M. Neal Golovin; Ahila Krishnamoorthy; Matthew Howard; James P. Perry
Original assignee: Daramic LLC
Current assignee: Daramic LLC
Priority date: 2015-10-07
Filing date: 2016-01-11
Publication date: 2017-04-13
Anticipated expiration: 2018-04-07
Also published as: CN115395177A; KR102680879B1; JP2018530127A; CN108292783A; JP2025134844A; KR20240042191A; EP3360194A4; EP3360194A1; JP2023116737A; JP2021177496A; KR20180066171A

Abstract

Improved battery separators are disclosed herein for use in flooded lead acid batteries, and in particular enhanced flooded lead acid batteries. The improved separators disclosed herein provide for enhanced electrolyte mixing and substantially reduced acid stratification. The improved flooded lead acid batteries may be advantageously employed in applications in which the battery remains in a partial state of charge, for instance in start/stop vehicle systems. Also, improved lead acid batteries, such as flooded lead acid batteries, improved systems that include a lead acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use may be provided.

Description

FLOODED LEAD ACID BATTERY WITH IMPROVED PERFORMANCE, IMPROVED BATTERY SEPARATORS, AND RELATED METHODS

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of co-pending U.S. provisional patent application Serial Number 62/238,373, filed October 7, 2015, which is incorporated herein by reference in its entirety.

FIELD

In accordance with at least selected embodiments, the present disclosure or invention is directed to improved lead acid batteries, such as flooded lead acid batteries, improved systems that include a lead acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use. In accordance with at least certain embodiments, the present disclosure or invention is directed to improved flooded lead acid batteries and/or improved battery separators for such batteries, and/or methods of manufacturing, testing, and/or using such improved flooded lead acid batteries. In addition, disclosed herein is a method, system, battery, and battery separator for reducing acid stratification, enhancing battery life and performance in a flooded lead acid battery.

BACKGROUND

In order to reduce fuel consumption and generation of tail pipe emissions, auto manufacturers have implemented varying degrees of electrical hybridization. One form of Hybrid Electric Vehicle (HEV) is sometimes referred as the "Micro HEV" or "micro-hybrid." In such Micro HEVs or similar vehicles, an automobile may have an idle start/stop (ISS) function in which the engine may shut off at various points during idle start/stop and/or regenerative braking. Although this increases the fuel economy of the vehicle, it also increases strain on the battery, which must power auxiliary devices (such as air conditioning, media players and the like) while the vehicle is not in motion.

Conventional vehicles (such as automobiles without start/stop capability) may use conventional flooded lead acid batteries such as SLI lead acid batteries. Because the engine never shuts off, power is only drawn from the battery when the engine is cranked. As such, the battery typically exists in a state of overcharge, not in a partial state of charge. For example, such a conventional flooded lead acid battery may exist in a state of charge that is greater than 95% charged, greater than 96%, greater than 97%, greater than 98%, greater than 99%, or even greater than 100% charged, as it is often in a state of overcharge. At overcharge, gas bubbles (for example hydrogen gas bubbles) are generated within the conventional lead acid battery, and these circulating gas bubbles serve to mix the liquid electrolyte (the acid) within the battery.

Start/stop vehicles, on the other hand, continuously draw power from the battery, which is therefore constantly in a state of partial charge. At partial charge, gas bubbles are not generated, and the internal mixing of the electrolyte is substantially reduced, leading to acid stratification within the battery. Thus, acid stratification is a problem within start/stop flooded lead acid batteries and various enhanced flooded batteries, whereas acid stratification simply was not a problem for more conventional or traditional flooded lead acid batteries, which operate in a state of overcharge or total (or close-to-total) charge. Acid stratification is a term for the process in which denser sulfuric acid is concentrated at the bottom of the battery, leading to a corresponding higher water concentration at the top of the battery. Acid stratification is undesirable within a flooded lead acid battery, such as an enhanced flooded lead acid battery or a start/stop flooded lead acid battery. The reduced levels of acid at the top of the electrode may inhibit uniformity and charge acceptance within the battery system and may increase the variation of internal resistance from top to bottom along the height of the battery. Increased acid levels at the bottom of the battery artificially raise the voltage of the battery, which can interfere with battery management systems, possibly sending unintended/erroneous state of health signals to a battery management system. Overall, acid stratification causes higher resistance along parts of the battery, which may lead to electrode issues and/or shorter battery life. Given that start/stop batteries and/or other enhanced flooded lead acid batteries are expected to become more and more prevalent with hybrid and fully electric vehicles to increase vehicle fuel efficiency and reduce C0₂ emissions, solutions for reducing acid stratification and/or for improving acid mixing are greatly needed.

In some instances, acid stratification can be avoided using VRLA (valve regulated lead acid) technology where the acid is immobilized by either a gelled electrolyte and/or by an absorbent glass mat (AGM) battery separator system. In contrast to the freely-fluid electrolyte in flooded lead acid batteries, in VRLA batteries the electrolyte is absorbed on a fiber or fibrous material, such as a glass fiber mat, a polymeric fiber mat, a gelled electrolyte, and so forth. However, VRLA battery systems are substantially more expensive to manufacture than flooded battery systems. VRLA-AGM technology in some instances, may be more sensitive to overcharging, may dry out in high heat, may experience a gradual decline in capacity, and may have a lower specific energy. Similarly, in some instances, gel VRLA technology may have higher internal resistance and may have reduced charge acceptance.

Thus, there is a need to further develop enhanced flooded lead acid batteries, such as enhanced flooded start/stop batteries, that do not undergo acid stratification while in use. There is a need for improved enhanced flooded lead acid batteries with improved uniformity and performance in comparison to what has been previously available, and with performance capability that rivals what may be found in certain VRLA-AGM batteries.

SUMMARY

In accordance with at least selected embodiments, the present disclosure or invention may address the above mentioned and other needs. For example, in accordance with at least certain embodiments, the present disclosure or invention is directed to new, improved or optimized flooded lead acid batteries, systems, and separators for enhanced flooded lead acid batteries, as well as methods of manufacturing, testing, and/or using the same.

Disclosed herein are new, improved or optimized enhanced flooded lead acid batteries having specific kinds of separators. It has been surprisingly found that by appropriate selection of separator surface characteristics, acid stratification can be reduced and/or prevented, and a corresponding increase in battery performance can be observed, performance that is close to, equates, or is even greater than the performance of certain VRLA-AGM batteries. Furthermore, it has been surprisingly found that using the separators described herein along with the batteries described herein, and using them in motion, such motion of the inventive batteries and separators facilitates the improved acid mixing or circulation, and/or the reduced or all-together prevented acid stratification, without a requirement for some mechanical means or some implement for acid mixing (such as a pump for acid mixing). Various embodiments are described in further detail below.

In accordance with at least selected embodiments, aspects or objects, the present disclosure or invention is directed to improved lead acid batteries, such as flooded lead acid batteries, improved systems that include a lead acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use.

In accordance with at least selected embodiments, aspects or objects, the present disclosure or invention may provide enhanced flooded lead acid batteries, such as enhanced flooded start/stop batteries, that do not undergo acid stratification while in use, improved enhanced flooded lead acid batteries with improved uniformity and performance in comparison to what has been previously available, and/or improved enhanced flooded lead acid batteries with performance capability that rivals or exceeds at least certain VRLA-AGM batteries.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 includes a series of photographs comparing cells with a serrated ribbed separator (these serrations may also be called embattlement ribs or embattlements) according to the invention (top row) with cells having a conventional solid ribbed separator (bottom row) where such solid ribs run vertically along the separator. Spacing between embattlement ribs (rib tip to rib tip) for separators shown in the top row was approximately 11 mm. Figure 1 shows the side of the battery separator that would typically face the positive electrode in the flooded lead acid battery (such as a flooded lead acid battery in a partial state of charge). However, such ribs may be included on both sides of the separator (e.g., may also be included on the side of the separator designed to face the negative electrode in the flooded lead acid battery). The cells shown in Figure 1 were subjected to 90 start/stop events or cycles. As shown in Figure 1, cells having serrated ribbed separators exhibit substantially less acid stratification than cells having conventional separators, after 30, 60, and 90 start/stop cycles or events.

Figure 2 includes a series of photographs comparing the same type of cells from Figure 1 with a serrated ribbed separator according to the invention (top row) with cells having a conventional solid ribbed conventional separator (bottom row). The cells were subjected to 60 start/stop events or cycles while in a vehicle traveling 25 miles an hour, followed by an overnight rest. As shown in Figure 2, cells having serrated ribbed separators exhibit substantially less acid stratification than cells having conventional separators. Such testing validated the lab findings shown in the photographs of Figure 1.

Figure 3 includes a series of photographs comparing cells with a closer spacing serrated ribbed separator according to the invention (top row) with cells having a conventional solid ribbed separator (bottom row) where the solid ribs are vertical along the separator. Spacing between embattlement ribs for separators shown in the top row was approximately 7 mm. The cells were subjected to 90 start/stop events or cycles. As shown in Figure 3, cells having serrated ribbed separators exhibit substantially less acid stratification than cells having conventional separators, after 30, 60, and 90 start/stop cycles or events.

Figure 4 includes a series of photographs comparing cells with a dimpled separator according to the invention (top row) with cells having a conventional separator that includes solid large and solid small ribs (bottom row) where such large and small solid ribs run vertically along the separator. The cells were subjected to 90 start/stop events or cycles. As shown in Figure 4, cells having dimpled separators exhibit substantially less acid stratification than cells having conventional separators, after 30, 60, and 90 start/stop cycles or events. Thus, the solid ribs (shown, for example, in the bottom row of photographs in Figure 4) actually inhibit acid mixing for the separator within a start/stop lead acid battery.

Figure 5 includes a series of photographs comparing cells with a dimpled separator according to the invention (top row) with cells having a separator that includes solid ribs running vertically along the separator combined with dimples (bottom row). The cells were subjected to 90 start/stop events or cycles. As shown in Figure 5, cells having dimpled separators (top row) exhibit less acid stratification than the start/stop lead acid battery cells in the bottom row having separators that include the combination of the solid ribs with the dimples. However, some acid mixing is shown in the bottom row (compared, for example, with the bottom rows of photographs in Figures 1-4). For example, in some of the pictures in the bottom row, a distinct area or pocket of low density of acid can be seen; however acid mixing can also be seen. The bottom row of photographs proves out that a combination of serrations and solid ribs, or a combination of dimples and solid ribs, may prove to be effective in various batteries, systems, and methods according to the present invention.

Figure 6 includes a set of photographs comparing cells with a dimpled separator according to the invention (top row) with cells having a separator that includes solid ribs running diagonally along the separator (at a slight angle relative to the vertical direction of the separator). The cells were subjected to 90 start/stop events or cycles. As shown in Figure 6, the cells having dimpled separators (top row) exhibit less acid stratification than the start/stop lead acid battery cells in photos such as those shown in the bottom rows of Figures 1-4. With regard to the bottom row of photographs of Figure 6, at 60 cycles or 60 start/stop events, one can see that some acid stratification still exists; however, the acid stratification improves at 90 cycles. Figures 7A and 7B include photographs comparing a conventional solid rib separator (7 A) and no separator at all (7B) in a jar filled with 1.28 specific gravity acid, which is mixed. Figure 7A includes a photograph of a conventional ribbed separator; acid stratification is indicated by the concentration of red acid at the bottom of the jar and the clear liquid toward the top of the jar. Figure 7B includes a photograph of a lead grid electrode only without any separator therein; much less acid stratification has taken place, as indicated by the red color throughout the jar. Figures 7 A and 7B help to illustrate that a solid ribbed conventional separator may hinder acid mixing and may promote acid stratification inside a start/stop flooded lead acid battery. Likewise, Figure 7B provides sort of a benchmark, containing no separator, against which the various separators can be compared and contrasted.

Figure 8 includes a photograph of cells constructed using a serrated ribbed separator according to the present invention before testing for acid stratification.

Figure 9 includes a photograph of the cells of Figure 8 assembled in a case for acid stratification testing. Lead straps are placed over the group of electrodes + separators. Once acid is added to the case, the acid level may be several mm above these lead straps (in some instances, by way of example only, about 3 mm above the lead straps). As this case containing electrodes and separator is tested for acid stratification within the cell, it may be preferred, in certain embodiments, that the direction of motion of the testing mimic the motion of the start/stop electric vehicle and is in the y-direction of the photograph of Figure 9, such that acid is moved over the face of the electrodes as the vehicle is started, accelerated, slowed, and/or stopped. This figure may also be viewed as if the top of the photograph of Figure 9 runs toward the front bumper of an electric vehicle with start/stop capability, while the bottom of the photograph of Figure 9 runs toward the rear bumper of the same electric vehicle, and the onlooker is looking down upon the group of electrodes + separator + lead straps, soon to be filled with acid for acid stratification testing.

Figure 10 includes a photograph of a cross-sectional view of a serration or a serrated rib on a separator used in accordance with various embodiments described herein.

Figure 11 includes two views of the profile of a serrated separator used in accordance with various embodiments described herein.

Figure 12 depicts a graph of the conductivity of sulfuric acid solutions at 25 degrees C. This graph aids in understanding that acid stratification can lead to non-uniform current due to differences in conductivity in the high and low acid regions of the cell and/or battery.

Figure 13 includes photographs of cells constructed similarly to the cells depicted in Figure 6. However, for the cells depicted in Figure 13, the separator was inserted into the system perpendicular to the direction of motion of the vehicle (whereas for the cells depicted in Figure 6, the separator was inserted into the system parallel to the direction of motion, similar to the directional descriptions of Figure 9 above). In various embodiments, it may be preferred that the separator is positioned parallel to the direction of motion for the vehicle and battery system. This is because the photographs shown in Figure 13 reveal that acid stratification is still taking place after 60 start/stop cycles or events without good acid mixing. Using the top row of Figure 13 as an example, even though a dimpled separator is used therein according to various embodiments of the present invention, acid stratification still took place, acid mixing was not optimal, all because of the placement of the battery and separator within the system.

Figure 14 includes a photograph of a battery separator containing serrated ribs according to various embodiments described herein, which separator was used to envelope electrodes for making a start/stop automotive flooded lead acid battery for testing, results of which testing are described below.

Figures 15A-15D include diagrams of several serrated profiles for a separator according to various embodiments herein. Various optimized profiles for separators for improving and enhancing acid mixing are disclosed herein, and the diagrams set forth in Figures 15A-15D are merely exemplary of such optimized profiles; many other optimized profiles fall within the scope of the improved separators, batteries, systems, and methods described and claimed herein.

Figure 16 includes a graph depicting a cycling test for one example of an enhanced flooded battery (or a flooded battery operating in an enhanced mode). In newer battery applications today, enhanced flooded batteries are operating in lower states of charge than previously known flooded lead acid batteries (which often operated in a state of overcharge or more than 100% charged). Thus, such an enhanced flooded battery may be operating in a state of charge (SoC) that is less than 95%, in some instances, less than 90%, in some instances, less than 85%, in some instances, less than 80%, in still some instances, less than 70%, in some instances, less than 60%, in some instances, less than 50%, in some instances, less than 25%o, in some instances, even less than 10%. In this particular graph, the cycling test was performed for a battery with a 17.5% depth of discharge (DoD), and the separator used was a conventional ribbed separator such as the one shown in the bottom row of photographs in Figure 1. This particular battery showed an ability to deliver energy, and to work well in a lead sulfate rich environment, under high cyclic conditions in a partially discharged state of charge. Batteries such as the one tested for Figure 16 and used in start/stop applications have a dramatically increased throughput of energy compared with standard SLI batteries (such as those set forth in standards such as EN50342). Because such enhanced flooded batteries and/or flooded batteries for start/stop applications are operating in a partial state of charge, they need to have higher charge efficiency and/or need to more readily accept charge. In certain instances, enhanced flooded batteries employ various additives in conjunction with one or more of the electrodes to increase charge efficiency and/or to create a battery that more readily accepts charge. The enhanced separator(s) described herein, however, can accomplish the same goal.

DETAILED DESCRIPTION

In various embodiments described herein, a separator is employed that enhances electrolyte mixing and/or circulation in a flooded lead acid battery. In certain embodiments, a separator is employed that reduces acid stratification. In various embodiments, a battery is disclosed in which acid stratification is greatly reduced compared with a known battery because of an improved or enhanced separator system for acid mixing and for preventing acid stratification. Such batteries may, for example, be used in vehicles with batteries that are in motion. And in various embodiments, the motion of the vehicle (for example, an electric vehicle containing a start/stop lead acid battery) for actually mixing the acid or electrolyte, combined with the enhanced battery separator described herein, results unexpectedly in the significant reduction in acid stratification shown herein as well as the significant improvement in acid mixing shown herein, within a start/stop flooded lead acid battery and/or an enhanced flooded lead acid battery or battery operating in an enhanced mode. For instance, the stopping and starting of the start/stop electric vehicle is providing the energy in various embodiments herein to mix the acid/electrolyte within the enhanced flooded lead acid batteries and to improve acid mixing and reduce or altogether prevent acid stratification. In accordance with at least certain embodiments, the polyolefm separator can be sheet of polyolefin having serrated ribs, protrusions, embattlements, dimples, embossments, and combinations thereof on one or more of its surfaces. In other embodiments, the polyolefin separator can be sheet of polyolefm having serrated ribs, protrusions, embattlements, dimples, embossments on one or more of its surfaces, combined with certain additives.

The separator is preferably made of a polyolefin, such as polypropylene, ethylene-butene copolymer, and preferably polyethylene, more preferably high molecular weight polyethylene, i.e., polyethylene having a molecular weight of at least 600,000, or high density polyethylene, e.g., polyethylene having a molecular weight of at least 500,000. In some embodiments, one or more ultra-high molecular weight polyethylenes are used, i.e., polyethylene having a molecular weight of at least 1,000,000, in particular more than 4,000,000, and in some instances 5,000,000 to 8,000,000 (measured by viscosimetry and calculated by Margolie's equation), a standard load melt index of substantially 0 (measured as specified in ASTM D 1238 (Condition E) using a standard load of 2,160 g) and a viscosity number of not less than 600 ml/g, preferably not less than 1,000 ml/g, more preferably not less than 2,000 ml/g, and most preferably not less than 3,000 ml/g (determined in a solution of 0.02 g of polyolefin in 100 g of decalin at 130°C).

In accordance with at least one embodiment, the separator is made up of an ultrahigh molecular weight polyethylene (UHMWPE) mixed with a processing oil and silica, for example, precipitated silica and/or fumed silica. In accordance with at least one other embodiment, the separator is made up of an ultrahigh molecular weight polyethylene (UHMWPE) mixed with a processing oil, additive and silica, for example, precipitated silica. The separator preferably comprises a homogeneous mixture of 8 to 100 vol. % of polyolefin, 0 to 40 vol. % of a plasticizer and 0 to 92 vol. % of inert filler material. In some instances, the preferred filler is dry, finely divided silica. However, the filler may be selected from the group consisting of: silica, mica, montmorillonite, kaolinite, asbestos, talc, diatomaceous earth, vermiculite, natural and synthetic zeolites, cement, calcium silicate, clay, aluminum silicate, sodium aluminum silicate, aluminum polysilicate, alumina silica gels, glass particles, carbon black, activated carbon, carbon fibers, charcoal, graphite, titanium oxide, iron oxide, copper oxide, zinc oxide, lead oxide, tungsten, antimony oxide, zirconia, magnesia, alumina, molybdenum disulfide, zinc sulfide, barium sulfate, strontium sulfate, calcium carbonate, magnesium carbonate, and the like, and various combinations thereof.

The preferred plasticizer is petroleum oil and/or a wax. Since the plasticizer is the component which is easiest to remove from the polymer-filler-plasticizer composition, it is useful in imparting porosity to the battery separator.

The separator has an average pore size of less than 1 μηι in diameter. Preferably more than 50% of the pores are 0.5 μιη or less in diameter. It may be preferred that at least 90% of the pores have a diameter of less than 0.9 μη . The microporous separator preferably has an average pore size within the range of 0.05 to 0.9 μηι, in some instances, 0.1 to 0.3 μ^ηι.

The pore size may be measured, in some instances, using the mercury intrusion method described in Ritter, H. L., and Drake, L.C., Ind. Eng. Chem. Anal. Ed., 17, 787 (1945). According to this method, mercury is forced into different sized pores by varying the pressure exerted on the mercury by means of a porosimeter (porosimeter model 2000, Carlo Erba). The pore distribution may be determined by evaluation of the crude data with the MILESTONE 200 software.

The thickness of the separator is preferably greater than 0.1 mm and less than or equal to 5.0 mm. The thickness of the separator can be within the range of 0.15 to 2.5 mm, 0.25-2.25 mm, 0.5-2.0 mm, 0.5-1.5 mm, or 0.75-1.5 mm (where such thicknesses take into account the thickness of the whole separator including any serrated rib, protrusion, dimple, etc.). In some instances, the separator can be approximately 0.8 mm or 1.1 mm thick. The separator may or may not have a laminate adhered to one or more of its surfaces.

In various embodiments, the microporous polyolefm separator layer contains ribs, such as serrated ribs. The preferred ribs may be 0.008 mm to 1 mm tall and may be spaced 0.001 mm to 20 mm apart, while the preferred backweb thickness of the microporous polyolefm separator layer without serrated ribs or embossments may be about 0.05 mm to about 0.500 mm (for instance, in certain embodiments, about 0.25 mm). For example, the ribs can be 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.25 mm, 2.5 mm, 2.75 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm apart. In some embodiments, the ribs may be in a pattern such as they may be on one side of the separator layer or on both sides of the polyolefm separator, from 0 to 90 degrees in relation to each other. Various patterns including ribs on both sides of the separator layer may include negative cross-ribs on the second side or back of the separator. Such negative cross-ribs may, in some instances, be 0.025 mm to about 0.1 mm in height.

The ribs may be serrated in certain preferred embodiments. The serrations may have an average tip length of from 0.05 mm to 1 mm. For example, the average tip length can be greater than or equal to 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm.

The serrations may have an average base length of from 0.05 mm to 1 mm. For example, the average base length can be greater than or equal to 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1mm.

The serrations may have an average height of from 0.05 mm to 4 mm. For example, the average height can be greater than or equal to 0.05 mm, 0.1mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1mm. For embodiments in which the serration height is the same as the rib height, the serrated ribs may also be referred to as protrusions. Such ranges may apply to separators for industrial traction-type start/stop batteries, where the total thickness of the separator may typically be about 1 to about 4 mm, as well as automotive start/stop batteries, where the total thickness of the separator may be a little less (e.g., typically about 0.3 mm to about 1mm).

The serrations can have an average center-to-center pitch of from 0.1 mm to 50 mm. For example, the average center-to-center pitch can be greater than or equal to 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.25 mm, or 1.5 mm; and/or less than or equal to 1.5 mm, 1.25 mm, 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, or 0.2 mm.

The serrations can have an average height to base width ratio of from 0.1:1 to 500:1. For example, the average height to base width ratio can be greater than or equal to 0.1:1, 25:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, or 450:1; and/or less than or equal to 500:1, 450:1, 400:1, 350:1, 300:1, 250:1, 200:1, 150:1, 100:1, 50:1, or 25:1.

The serrations can have average base width to tip width ratio of from 1000 : 1 to 0.1 : 1. For example, the average base width to tip width ratio can be greater than or equal to 0.1:1, 1:1, 2:1, 3:1,4:1, 5:1,6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 25:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350: 1, 450: 1, 500:1, 550: 1, 600:1, 650:1, 700:1, 750:1, 800: 1, 850: 1, 900:1, 950:1, and/or less than or equal to 1000: 1, 950:1, 900:1, 850: 1, 800:1, 750: 1, 700:1, 650:1, 600:1, 550:1, 500: 1, 450:1, 400: 1, 350:1, 300: 1, 250:1, 200: 1, 150:1, 100:1, 50: 1, 25:1, 20:1, 15:1, 10: 1, 9: 1, 8:1, 7: 1, 6:1, 5:1, 4: 1, 3: 1, 2:1, or 1 : 1.

In some embodiments, the separator can be dimpled. Dimples are typically protrusion- type features on one or more surfaces of the separator. The thickness of the dimples can be from 1-99% the thickness of the separator. For examples, the average thickness of the dimples can be less than 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%), 10%, or 5%> that of the separator. Dimples may be arranged in rows along the separator. The rows or lines may be spaced 0.001 mm to 10 mm apart. For example, the rows can be 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.25 mm, 2.5 mm, 2.75 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm apart. Conversely, the dimples may be arranged in a random array or random manner.

The dimples may have an average dimple length of from 0.05 mm to 1 mm. For example, the average dimple length can be greater than or equal to 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm.

The dimples may have an average dimple width of from 0.01 mm to 1 mm. For example, the average dimple width can be greater than or equal to 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm. The dimples can have an average center-to-center pitch of from 0.1 mm to 50 mm. For example, the average center-to-center pitch can be greater than or equal to 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.25 mm, or 1.5 mm; and/or less than or equal to 1.5 mm, 1.25 mm, 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, or 0.2 mm.

The dimples can be quadrangular in shape, for instance, square and rectangles. The dimples can have an average dimple length to dimple width ratio of from 0.1:1 to 100:1. For example, the average length to base width ratio can be greater than or equal to 0.1:1, 1:1, 2:1, 3:1,4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 25:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 450:1, 500:1,550:1, 600:1, 650:1, 700:1, 750:1, 800:1, 850:1, 900:1, 950:1, and/or less than or equal to 1000:1, 950:1, 900:1, 850:1, 800:1, 750:1, 700:1, 650:1, 600:1, 550:1, 500:1, 450:1, 400:1, 350:1, 300:1, 250:1, 200:1, 150:1, 100:1, 50:1, 25:1,20:1, 15:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, or 1:1.

In some embodiments, the dimples can be substantially circular. Circular dimples can have a diameter from about 0.05 to 1.0 mm. For example, the average dimple diameter can be greater than or equal to 0.05 mm, 0.1mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, or 0.9 mm; and/or less than or equal to 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, or 0.1 mm.

Various other shapes for the dimples may be included as well. By way of example only, such dimples might be triangular, pentagonal, hexagonal, heptagonal, octagonal, and so forth.

In some embodiments, the separator can feature a combination of serrations and/or dimples. For instance, a separator can have a series of serrated ribs running top to bottom along the separator, and a second series of serrated ribs running horizontally along the separator. In other embodiments, the separator can have an alternating sequence of serrated ribs, dimples and/or continuous and/or interrupted solid ribs.

Table 1 just below includes several specific embodiments of separators having serrations and/or dimples and various parameters that may be used in forming such separators so as to prevent acid stratification and enhance acid mixing with a flooded lead acid battery (sometimes referred to as an enhanced flooded battery).

Table 1

Separator Backweb Separator Spacing Cross-Ribs Serrated Rib Samples thickness Thickness between Profile and/or Dimple

(mm) with rib ribs (mm) (mm) Features

(mm)

Serrated separator 0.25 0.85 7 0.75 tall; 2.5 mm profile spacing between serrations in a single row

Serrated separator 0.25 1.0 11 0.075 1 mm spacing profile 2 between serrations in a single row.

Large Dimple 0.25 1.0 12.3 mm spacing separator profile in one or more

directions; 18 mm spacing in one or more directions.

Small Dimple 0.25 0.7 9 mm spacing in separator profile one or more

directions; 5 mm spacing in one or more directions.

The separators disclosed herein preferably provide enhanced electrolyte mixing and/or acid circulation compared with conventional separators. In certain embodiments, the separators provide for less acid stratification, as measured by electrolyte density at the top and bottom of the cell. The density differential may be less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2.5% or 1%, after the cell has undergone 30, 60 or 90 start/stop events or cycles. In certain selected embodiments, the density differential may be less than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 2.5% or 1%, after the cell has remained still for 24, 48, or 72 hours.

The separator used in various embodiments herein may be provided with one or more additives. Such is the case because additives may enhance separators for certain stop/start flooded lead acid batteries for certain vehicles. One such additive that may be present in the polyolefin is a surfactant, while another such additive may include one or more latex additives. Suitable surfactants include surfactants such as salts of alkyl sulfates; alkylarylsulfonate salts; alkylphenol-alkylene oxide addition products; soaps; alkyl-naphthalene-sulfonate salts; dialkyl esters of sulfo-succinate salts; quaternary amines; block copolymers of ethylene oxide and propylene oxide; and salts of mono and dialkyl phosphate esters. The additive can be a non- ionic surfactant such as polyol fatty acid esters, polyethoxylated esters, polyethoxylated fatty alcohols, alkyl polysaccharides such as alkyl polyglycosides and blends thereof, amine ethoxylates, sorbitan fatty acid ester ethoxylates, organosilicone based surfactants, ethylene vinyl acetate terpolymers, ethoxylated alkyl aryl phosphate esters and sucrose esters of fatty acids.

In certain embodiments, the additive can be represented by a compound of Formula (I)

R(OR COOM^x+ _1/x)_m (I)

in which

• R is a non-aromatic hydrocarbon radical with 10 to 4200 carbon atoms, preferably 13 to

4200, which can be interrupted by oxygen atoms,

. R¹ is H,— (CH₂)_kCOOM^x+ _1/x or— (CH₂)_k— S0₃M^x+ _1/x, preferably H, where k is 1 or 2, • M is an alkali metal or alkaline-earth metal ion, H⁺ or NH₄ ⁺, where not all the variables M simultaneously have the meaning H⁺,

• n is O or l,

• m is 0 or an integer from 10 to 1400 and

• x is 1 or 2,

the ratio of oxygen atoms to carbon atoms in the compound according to Formula (I) being in the range from 1 : 1.5 to 1 :30 and m and n not being able to simultaneously be 0. However, preferably only one of the variables n and m is different from 0.

By non-aromatic hydrocarbon radicals is meant radicals which contain no aromatic groups or which themselves represent one. The hydrocarbon radicals can be interrupted by oxygen atoms, i.e. contain one or more ether groups.

R is preferably a straight-chain or branched aliphatic hydrocarbon radical which can be interrupted by oxygen atoms. Saturated, uncross-linked hydrocarbon radicals are quite particularly preferred.

The use of the compounds of Formula (I) for the production of an additive for various battery separators described herein may also provide such separators with effective protection against oxidative destruction. In some embodiments, battery separators are preferred which include an additive containing a compound according to Formula (I) in which

• R is a hydrocarbon radical with 10 to 180, preferably 12 to 75 and quite particularly

preferably 14 to 40 carbon atoms, which can be interrupted by 1 to 60, preferably 1 to 20 and quite particularly preferably 1 to 8 oxygen atoms, particularly preferably a hydrocarbon radical of formula R²— [(OC₂H₄)_p(OC₃H₆)_q]— , in which o R is an alkyl radical with 10 to 30 carbon atoms, preferably 12 to 25, particularly preferably 14 to 20 carbon atoms,

o P is an integer from 0 to 30, preferably 0 to 10, particularly preferably 0 to 4 and

o q is an integer from 0 to 30, preferably 0 to 10, particularly preferably 0 to 4,

o compounds being particularly preferred in which the sum of p and q is 0 to 10, in

particular 0 to 4,

• n is 1 and

• m is 0.

Formula R— [(OC₂H4)_p(OC₃H₆)_q]— is to be understood as also including those compounds in which the sequence of the groups in square brackets differs from that shown. For example according to the invention compounds are suitable in which the radical in brackets is formed by alternating (OC₂H₄) and (OC₃H₆) groups.

Additives in which R is a straight-chain or branched alkyl radical with 10 to 20, preferably 14 to 18 carbon atoms have proved to be particularly advantageous. OC₂H₄ preferably stands for OCH₂CH₂, OC₃H₆ for OCH(CH₃)CH₂ and/or OCH₂CH(CH₃).

As preferred additives there may be mentioned in particular alcohols (p=q=0; m=0) primary alcohols being particularly preferred, fatty alcohol ethoxylates (p=l to 4, q=0), fatty alcohol propoxylates (p^O; q=l to 4) and fatty alcohol alkoxylates (p=l to 2; q=l to 4) ethoxylates of primary alcohols being preferred. The fatty alcohol alkoxylates are for example accessible through reaction of the corresponding alcohols with ethylene oxide or propylene oxide.

Additives of the type m=0 which are not, or only partially, soluble in water and sulphuric acid have proved to be particularly advantageous. Also preferred are additives which contain a compound according to Formula (I), in which

• R is an alkane radical with 20 to 4200, preferably 50 to 750 and quite particularly preferably 80 to 225 carbon atoms,

• M is an alkali metal or alkaline-earth metal ion, H⁺ or NH₄ ⁺, in particular an alkali metal ion such as Li⁺, Na⁺ and K⁺ or H⁺, where not all the variables M simultaneously have the meaning H⁺,

• n is 0,

• m is an integer from 10 to 1400 and

• x is 1 or 2.

As suitable additives there may be mentioned here in particular polyacrylic acids, polymethacrylic acids and acrylic acid-methacrylic acid copolymers, whose acid groups are at least partly, i.e. preferably 40%, particularly preferably 80%, neutralized. The percentage refers to the number of acid groups. Quite particularly preferred are poly(meth)acrylic acids which are present entirely in the salt form. By poly(meth)acrylic acids are meant polyacrylic acids, polymethacrylic acids and acrylic acid-methacrylic acid copolymers. Poly(meth)acrylic acids are preferred and in particular polyacrylic acids with an average molar mass M_w of 1,000 to 100,000 g/mol, particularly preferably 1,000 to 15,000 g/mol and quite particularly preferably 1,000 to 4,000 g/mol. The molecular weight of the poly(meth)acrylic acid polymers and copolymers is ascertained by measuring the viscosity of a 1% aqueous solution, neutralized with sodium hydroxide solution, of the polymer (Fikentscher's constant).

Also suitable are copolymers of (meth)acrylic acid, in particular copolymers which, besides (meth)acrylic acid contain ethylene, maleic acid, methyl acrylate, ethyl acrylate, butyl acrylate and/or ethylhexyl acrylate as comonomer. Copolymers are preferred which contain at least 40 wt.-%, preferably at least 80 wt.-% (meth)acrylic acid monomer, the percentages being based on the acid form of the monomers or polymers.

To neutralize the polyacrylic acid polymers and copolymers, alkali metal and alkaline-earth metal hydroxides such as potassium hydroxide and in particular sodium hydroxide are particularly suitable.

The microporous polyolefm can be provided in various ways with the additive or additives. The additives can for example be applied to the polyolefm when it is finished (i.e. after the extraction) or added to the mixture used to produce the polyolefm. According to a preferred embodiment the additive or a solution of the additive is applied to the surface of the polyolefm. This variant is suitable in particular for the application of non-thermostable additives and additives which are soluble in the solvent used for the subsequent extraction. Particularly suitable as solvents for the additives according to the invention are low-molecular-weight alcohols, such as methanol and ethanol, as well as mixtures of these alcohols with water. The application can take place on the side facing the negative electrode, the side facing the positive electrode or on both sides of the separator.

The additive can be present at a density of at least 0.5 g/m², 1.0 g/m², 1.5 g/m², 2.0 g/m², 2.5 g/m², 3.0 g/m², 3.5 g/m², 4.0 g/m², 4.5 g/m², 5.0 g/m², 5.5 g/m², 6.0 g/m², 6.5 g/m², 7.0 g/m², 7.5 g/m², 8.0 g/m², 8.5 g/m², 9.0 g/m², 9.5 g/m² or 10.0 g/m². The additive can be present on the separator at a density between 0.5-10 g/m², 1.0-10.0 g/m², 1.5-10.0 g/m², 2.0-10.0 g/m², 2.5-10.0 g/m², 3.0-10.0 g/m², 3.5-10.0 g/m², 4.0-10.0 g/m², 4.5-10.0 g/m², 5.0-10.0 g/m², 5.5-10.0 g/m², 6.0-10.0 g/m², 6.5-10.0 g/m², 7.0-10.0 g/m², 7.5-10.0 g/m², 5.0-10.5 g/m², 5.0-11.0 g/m², 5.0- 12.0 g/m², or 5.0-15.0 g/m². The application may also take place by dipping the polyolefin in the additive or a solution of the additive and subsequently optionally removing the solvent, e.g. by drying. In this way the application of the additive can be combined for example with the extraction often applied during polyolefin production.

The separators, methods, batteries, and battery systems described herein may provide improved electrolyte circulation and mixing with less acid stratification over time. This is especially important for deep cycling and/or enhanced flooded lead acid batteries, wherein acid stratification can significantly reduce battery performance. Various flooded lead acid batteries, enhanced flooded lead acid batteries, and applications therewith may benefit from the improved separators, methods, batteries, and systems described herein. Various start/stop vehicles, including but not limited to, various electric vehicles, automobiles, hybrid vehicles, fork trucks, golf carts, neighborhood electric vehicles, and so forth may benefit from the improved separators, batteries, battery systems, and methods described herein, particularly vehicles and/or batteries that do not get charged adequately or do not reach a state of 100% charge (or overcharge) and exist in a partial state of charge.

The enhanced flooded separators (also referred to as acid mixing separators) described herein for use in enhanced flooded batteries, particularly batteries in motion, surprisingly and unexpectedly provide such enhanced flooded batteries with significantly improved acid mixing and/or acid circulation, thereby significantly reducing or altogether preventing acid stratification within the enhanced flooded battery. Such may be vitally important, as the flow and circulation of acid along the entire separator means that the entire battery is being used versus some smaller portion of the battery being in use. Namely, using the enhanced separators, batteries, systems, and methods of the present invention, electrolyte (e.g., sulfuric acid) is freely flowing to and along all or almost all parts of the separator and therefore is freely flowing to and along all or almost all parts of the positive active material and the negative active material on the electrodes. Conversely, with acid stratification (see, by way of example only, the acid stratification present in the bottom rows of photographs in Figures 1-4, where red-colored indicator has been added to the acid such that acid is clearly visible and present in about the bottom halves of those test cells versus clear liquid, namely water, clearly visible and present in about the top halves of those test cells), entire portions of the separator, and therefore entire portions of the positive active material and negative active material on either side of such separator, are completely devoid of acid and therefore are not being used to their fullest potential to provide power to the underlying device/vehicle using the battery. Thus, the improved separators, batteries, systems, and methods described herein greatly reduce acid stratification in a flooded lead acid battery, for example, an enhanced flooded battery.

The reason for concern about acid stratification is the resulting current density non- uniformity across the surface of the positive and negative plates or electrodes. The graph shown in Figure 12 illustrates the conductivity of H₂S0₄ vs. concentration.

In some preferred embodiments of the present invention, the serrations present on one or more surfaces of the separator are non-uniformly distributed. Additionally, in some preferred embodiments, the dimples present on one or more surfaces of the separator are non-uniformly distributed. For example, the serrations and dimples themselves may be non-uniform in size (e.g., may be sized randomly), and the spacing between the serrations and/or dimples may be random and/or non-uniform. By way of example, various serrations and/or dimples used herein may be present on one or both surfaces of a separator in an ordered or a disordered array. Additionally, various ribs used herein, e.g., serrated ribs, may be non-linear. For example, some serrated ribs may be wavy in pattern or non-linear in pattern.

In various embodiments, the effects of the enhanced flooded separators for the enhanced flooded batteries described herein are highlighted when the separator is positioned within the enhanced flooded battery such that the enhancements on the separator run parallel with the direction of motion in which a battery in motion is traveling. Such effects can be seen by comparing the desirable results of Figure 6 with the less desirable results of Figure 13. In the photographs in Figure 13, acid stratification is still observed even though separators having enhanced profiles for acid mixing are used. This is because the cells in Figure 13 were positioned such that the enhancements on the separator and electrodes are perpendicular to the direction of motion in which the battery is traveling in the vehicle. The placement of the battery in the vehicle with the electrodes and separators parallel to the start and stop inertia will allow for better mixing of acid than perpendicular positioning. When perpendicular, the electrodes and separators hinder acid turbulence and mixing rather than promote it.

The various enhanced separators described herein, for example, those with serrations for improving acid mixing and acid circulation, may have different spacing and/or different patterns. By way of example only, Figures 15A-15D show examples of serrated ribs that may be effective in the present invention. Such patterns, and other patterns (both uniform and non-uniform, and both ordered and disordered) may allow for improved CCA (cold cranking amperage) within the flooded lead acid battery as well as other key improvements in electrical performance of the battery. In serration patterns like the ones featured in Figures 15A-15D (by way of example only), there is about a 53% reduction in surface area vs. a separator having a solid rib (a control) allowing for less rib contact on the PAM (the positive active material) resulting in improved CCA performance. In such patterns like the ones shown in Figures 15A-15D, there may be 33% less rib mass, compared with a solid rib profile (a control) allowing for more acid availability and improved performance. Additionally, it may be important to maintain PAM (positive active material) compression with a balance of rib mass and openings for acid mixing and availability.

Further, the placement of the protrusion(s) (such as dimples, serrations or the like) and design are preferably be optimized for compression as not to facilitate PAM shedding and preferred to be supported over the grid frame as not to push the pellet from intimate contact with the positive grid frame or current collector.

The batteries of the present invention may provide for cost savings with less lead needed for superior performance resulting from increased PAM utilization. In turn, such could lower the cost of the battery, which is a need for car makers, and could lower the weight of the battery, which is also a need for car makers.

In some instances, the enhanced separators used in the present invention may have optimized profiles that have a rib surface area, compared with the rib surface area of a conventional rib profile such as a solid vertical rib profile, that is 10-90% of that conventional rib surface area, preferably 30-70% of that conventional rib surface area, and more preferably, in some instances, 40-60%> of that conventional rib surface area. All of this depends on the rib geometry, rib spacing and the final goal of improving the acid mixing and preventing the acid stratification, all of which are optimized.

Examples

Figures 8 and 9 show battery experiments that were conducted in a cell container. The battery test cell shown in these photographs with a white case and a group of lead electrodes, had the following general properties:

Table 2

In additional examples, shown below, a commercial group 31 19 plate/ group Ca/ Ca expanded battery testing data. In this table, the separators marked "new" have the serrated profile shown in the envelope of Figure 14, while the results marked "control" have solid ribs along the separator vertically. These results proved out unexpected and/or surprising findings regarding the improvement in battery performance for start/stop enhanced flooded lead acid batteries using enhanced separators according to the present invention. Significantly, the results in the table below showed improvements even when the batteries had not been placed into significant motion in a vehicle but rather had just been in general motion while moving from place to place within a plant for testing. Thus, combined with the motion from a vehicle and/or the energy from various start/stop events, the battery performance results may improve even more significantly.

Table 3

New to

ControlAvg

improvement 48 33.5 0.101

%

Improvement 3.5% 3.6% 0.8%

Std deviation

improvement (1.17) (5.99) (0.00)

Improved

Cold

Cranking

Higher discharge with

performance with standard

Comments improved quality deviation

The significance of this Midtronic's CCA test is that is not a Global Standard test but a hand held device using an algorithm to quickly and easily calculate the performance of the battery. The increase of surface area of the Positive Grid exposed to acid using the acid mixing separator allows for improved conductance and improved electrode performance. Although not an industry standard it is used for simplicity and ease of use for purchasing decisions around the world today. Improving the performance of this algorithm tester is key to customer satisfaction and the improvements of the acid mixing separator facilitates that result as demonstrated in table 3#.

The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims. Any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof and are open, non-limiting terms. Although the terms "comprising" and "including" have been used herein to describe various embodiments, the terms "consisting essentially of and "consisting of can be used in place of "comprising" and "including" to provide for more specific embodiments of the invention and are also disclosed. Other than where noted, all numbers expressing geometries, dimensions, and so forth used in the specification and claims are to be understood at the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference.

Claims

CLAIMS What is claimed is:

1. An improved stop/start flooded lead acid battery comprising a microporous polyolefm battery separator, wherein the separator comprises serrated ribs, interrupted ribs, dimples or combinations thereof, and wherein the stop/start flooded lead acid battery has enhanced or improved acid mixing and/or reduced acid stratification relative to a conventional stop/start or ISS flooded lead acid battery.

2. The battery according to claim 1, wherein the microporous polyolefm battery separator comprises polyethylene.

3. The battery according to either of claims 1 or 2, wherein the battery separator further comprises a filler.

4. The battery according to any of claims 1-3, wherein the battery separator further comprises a surfactant or an additive.

5. The battery according to any of claims 1-4, comprising a separator comprising a plurality of rows of serrated ribs, interrupted ribs, dimples, or combinations thereof, wherein the rows are spaced 0.1-20 mm apart.

6. The battery according to any of claims 1-5, wherein the battery is in motion and wherein the motion provides energy for the enhanced or improved acid mixing.

7. A method for reducing acid stratification in a battery, comprising the steps of: providing an alternating sequence of positive and negative electrodes;

providing a separator between each of the electrodes, wherein the separator comprises a microporous polyolefin battery separator, wherein the separator comprises serrated ribs, interrupted ribs, dimples or combinations thereof; and

submerging the electrodes in liquid electrolyte.

8. In an enhanced flooded battery, the improvement comprising the battery according to any of claims 1-6.

9. An enhanced flooded battery comprising the separator according to any of claims 1-6.

10. A solid rib separator comprising mechanically induced serrations from creasing in a nip point or calendaring process.

1 1. A method of testing batteries by inducing motion of acceleration and deceleration to facilitate acid mixing in the presence of an acid mixing separator thereby reducing acid stratification.

12. A separator with reduced mass resulting in reduced acid displacement allowing for more useable electrolyte between the electrodes.

13. A separator that improves the conductance of the battery allowing for improved state of health and/or communications with electronic devices in the battery monitoring system or battery management system, such as located in a vehicle or hand held monitoring device.

14. Improved lead acid batteries, such as flooded lead acid batteries, improved systems that include a lead acid battery and a battery separator, improved battery separators, improved vehicles including such systems, and/or methods of manufacture and/or use; improved flooded lead acid batteries and/or improved battery separators for such batteries, and/or methods of manufacturing, testing, and/or using such improved flooded lead acid batteries; a method, system, battery, and battery separator for reducing acid stratification, enhancing battery life and performance in a flooded lead acid battery; and/or improved or enhanced flooded lead acid batteries, such as enhanced flooded start/stop batteries, that do not undergo acid stratification while in use, improved enhanced flooded lead acid batteries with improved uniformity and performance in comparison to what has been previously available, and/or improved enhanced flooded lead acid batteries with performance capability that rivals or exceeds at least certain VRLA-AGM batteries.

15. An improved flooded lead acid battery comprising a microporous polyolefin battery separator, wherein the separator comprises serrated ribs, interrupted ribs, dimples or combinations thereof, and wherein the stop/start flooded lead acid battery has enhanced or improved acid mixing and/or reduced acid stratification relative to a conventional flooded, stop/start or ISS flooded lead acid battery.