WO2017027037A1

WO2017027037A1 - Improved separators for flat plate batteries

Info

Publication number: WO2017027037A1
Application number: PCT/US2015/045060
Authority: WO
Inventors: Surendra Kumar Mittal; Naveen Prabhu SHANMUGAM; J. Kevin Whear; Eric H. Miller
Original assignee: Daramic, Llc
Priority date: 2015-08-13
Filing date: 2015-08-13
Publication date: 2017-02-16
Also published as: WO2017027765A1; CN113644381A; CN108352481A; CN108352481B

Abstract

Disclosed herein are novel or improved separators, battery separators, flat plate separators, batteries, cells, and/or methods of manufacture and/or use of such separators, battery separators, flat plate separators, cells, and/or batteries. In accordance with at least certain embodiments, the present disclosure or invention is directed to novel or improved lead acid battery separators for flat plate cycling batteries, flat plate deep cycling batteries, flat plate inverter batteries, flat plate UPS batteries, flat plate home UPS batteries, flat plate long cycle life batteries, deep cycle stationary, traction, inverter, or fork lift batteries, flooded batteries, UPS, ESS, BESS, flat plate cells, and/or improved methods of making and/or using such improved separators, cells, batteries, systems, and/or the like. In accordance with at least certain embodiments, the present disclosure or invention is directed to an improved separator for flat plate stationary batteries and/or improved methods of using such batteries having such improved separators. In addition, disclosed herein are methods, systems and battery separators for enhancing battery life, reducing water loss, and/or improving uniformity in at least flat plate stationary batteries. In accordance with at least particular embodiments, the present disclosure or invention is directed to an improved separator for flat plate batteries wherein the separator includes performance enhancing additives or coatings, hybrid envelopes, cross rib shapes or profiles, and/or the like.

Description

IMPROVED SEPARATORS FOR FLAT PLATE BATTERIES

FIELD

In accordance with at least selected embodiments, the present disclosure or invention is directed to novel or improved separators, battery separators, flat plate separators, batteries, cells, and/or methods of manufacture and/or use of such separators, battery separators, flat plate separators, cells, and/or batteries. In

accordance with at least certain embodiments, the present disclosure or invention is directed to novel or improved lead acid battery separators for flat plate cycling batteries, flat plate deep cycling batteries, flat plate inverter batteries, flat plate UPS batteries, flat plate home UPS batteries, flat plate long cycle life batteries, deep cycle stationary, traction, inverter, or fork lift batteries, flooded batteries, UPS, ESS, BESS, flat plate cells, and/or improved methods of making and/or using such improved separators, cells, batteries, systems, and/or the like. In accordance with at least certain embodiments, the present disclosure or invention is directed to an improved separator for flat plate stationary batteries and/or improved methods of using such batteries having such improved separators. In addition, disclosed herein are methods, systems and battery separators for enhancing battery life, reducing water loss, and/or improving uniformity in at least flat plate stationary batteries. In accordance with at least particular

embodiments, the present disclosure or invention is directed to an improved separator for flat plate batteries wherein the separator includes performance enhancing additives or coatings, hybrid envelopes, cross rib shapes or profiles, and/or the like.

BACKGROUND

One type of lead acid flooded or VLA battery is known as a flat plate deep cycle battery (or more simply, a flat plate battery). These batteries are often employed in high-temperature and partial charge applications, such as found in inverters, photo voltaic systems, and the like. When used for deep cycling applications, flat plate stationary batteries tend to remain under charged or in a partial state of charge.

Accordingly, the battery's efficiency and/or charge time diminish over the life of the battery. Under such operating conditions, the battery plates deteriorate due to sulphation (or sulfation), and the battery life ends prematurely. Furthermore, under the typical float charging voltage, for instance, about 13.8V to 14.4V, flat plate deep cycle batteries do not fully recover after a deep discharge. However, simply increasing the float charging voltage is not a general solution, because higher voltages accelerate the corrosion of the grid and may reduce cycle life.

In the deep cycling applications such as inverter batteries, the key requirements include better re-chargeability, improved backup time as well as lower water loss to reduce maintenance needs. However, improvement of one criteria can be

accompanied by a corresponding deleterious effect to another aspect of battery performance. For example, while it is possible to reduce the water loss in a battery with certain coatings, battery charge acceptance is usually compromised by the coating process. In some instances, such as in U.S. Patent No. 6,703,161 owned by Daramic,

LLC of

Charlotte, NC, and incorporated by reference herein, there have been disclosed battery separators for lead acid storage batteries that are, for instance, multi-layer battery separators.

There is a need for at least certain applications or batteries for an improved separator which overcomes the aforementioned problems, for deep cycle batteries having improved re-chargeability under float charging conditions, or for deep cycle batteries having reduced rates of water loss and grid corrosion.

SUMMARY

In accordance with at least selected embodiments, the present disclosure or invention may address the above issues or needs. In accordance with at least certain objects, the present disclosure or invention may provide an improved separator which overcomes the aforementioned problems, deep cycle batteries having improved re- chargeability under float charging conditions, deep cycle batteries having reduced rates of water loss and grid corrosion, and/or the like.

In accordance with at least selected embodiments, the present disclosure or invention may address the above issues or needs and/or may provide novel or improved In accordance with at least selected embodiments, the present disclosure or invention is directed to novel or improved separators, battery separators, flat plate separators, batteries, cells, and/or methods of manufacture and/or use of such separators, battery separators, flat plate separators, cells, and/or batteries. In accordance with at least certain embodiments, the present disclosure or invention is directed to novel or improved lead acid battery separators for flat plate cycling batteries, flat plate deep cycling batteries, flat plate inverter batteries, flat plate UPS batteries, flat plate home UPS batteries, flat plate long cycle life batteries, deep cycle stationary, traction, inverter, or fork lift batteries, flooded batteries, UPS, ESS, BESS, fork truck, pallet jack, golf car, or scissor lift batteries, flat plate cells, and/or improved methods of making and/or using such improved separators, cells, batteries, systems, and/or the like. In accordance with at least certain embodiments, the present disclosure or invention is directed to an improved separator for flat plate stationary batteries and/or improved methods of using such batteries having such improved separators. In addition, disclosed herein are methods, systems and battery separators for enhancing battery life, reducing water loss, and/or improving uniformity in at least flat plate stationary batteries. In accordance with at least particular embodiments, the present disclosure or invention is directed to an improved separator for flat plate batteries wherein the separator includes performance enhancing additives or coatings, hybrid envelopes, cross rib shapes or profiles, and/or the like.

Disclosed herein are novel or improved separators for lead acid batteries. The separators preferably include or contain performance enhancing additives, hybrid envelope shapes, and/or ribbed surfaces.

In accordance with at least one embodiment, a separator in the shape of a hybrid envelope is provided. The separator can be a porous membrane, for instance a porous polyolefin such as polyethylene. The hybrid envelope can contain one or more openings or slits along the bottom edge. Preferably, the openings are not disposed in a corner of the envelope.

A plurality of ribs may be disposed upon the inner face of the envelope. A plurality of ribs may be disposed upon the outer face of the envelope in a direction different than the ribs upon the inner face (cross ribs). The ribs of the inner and outer faces may be substantially perpendicular to each other. The ribs of the outer face (the negative face) may be mini-ribs or mini-cross ribs (smaller and more closely spaced than the positive or inner face ribs).

The separator may contain a surfactant additive along with other additives or agents, residual oil, and fillers.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 photographically depict the difference between a separator shaped into a hybrid envelope (Fig. 1A) with slits or openings and a separator in a more

conventional envelope (Fig. 1B).

Figure 2A, 2B and 2C depict the discharge (as a percentage of initial discharge) over the course of 168 cycles (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator (lowest trace), a ribbed separator having an additive and in the shape of a conventional envelope (middle trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 3A, 3B and 3C depict the discharge (as a percentage of initial discharge) over the course of 168 cycles (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 4A, 4B and 4C depict the comparative recharge over the course of 168 cycles (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 5A, 5B and 5C depict the comparative specific gravity over the course of 50 cycles (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 6A, 6B and 6C depict the comparative recharge profile (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator and a ribbed separator having an additive and in the shape of a hybrid envelope.

Figure 7A, 7B and 7C depict the comparative discharge duration/backup time during inverter battery cycling tests (discharging at 43A to 10.5 V, charging at 13.9 V for 10 hour) for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 8A, 8B and 8C depict the comparative recharge input data in Ah during inverter battery cycling tests for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace). Figure 9A, 9B and 9C depict the comparative specific gravity during inverter battery cycling tests for a flat plate inverter battery having a conventional separator (bottom trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (top trace).

Figure 10 depicts the comparative water loss for a flat plate inverter battery having a conventional separator and a ribbed separator having an additive and in the shape of a hybrid envelope.

Figures 11 A, 11 B, 11C, 11 D, 11 E, and 11 F depict the comparative water loss for a flat plate inverter battery having a conventional separator (top trace) and a ribbed separator having an additive and in the shape of a hybrid envelope (bottom trace).

DETAILED DESCRIPTION

The inventive separator is preferably a porous membrane (such as a

microporous membrane having pores less than about 1 micron, mesoporous, or a macroporous membrane having pores greater than about 1 micron) made of natural or synthetic materials, such as polyolefin, polyethylene, polypropylene, phenolic resin, PVC, rubber, synthetic wood pulp (SWP), glass fibers, cellulosic fibers, or combinations thereof, more preferably a microporous membrane made from thermoplastic polymers. The preferred microporous membranes may have pore diameters of about 0.1 micron (100 nanometers) and porosities of about 60%. The thermoplastic polymers may, in principle, include all acid-resistant thermoplastic materials suitable for use in lead acid batteries. The preferred thermoplastic polymers include polyvinyls and polyolefins. The polyvinyls include, for example, polyvinyl chloride (PVC). The polyolefins include, for example, polyethylene, ultrahigh molecular weight polyethylene (UHMWPE), and polypropylene. One preferred embodiment may include a mixture of filler (for example, silica) and UHMWPE. In general, the preferred separator may be made by mixing, in an extruder, about 30% by weight silica with about 10% by weight UHMWPE, and about 60% processing oil. The mixture may also include minor amounts of other additives or agents as is common in the separator arts (such as wetting agents, colorants, antistatic additives, and/or the like) and is extruded into the shape of a flat sheet.

One such additive that may be present in the separator is a surfactant. Suitable surfactants include surfactants such as salts of alkyi 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 alcohols, alkyi polysaccharides such as alkyi polyglycosides and blends thereof, amine ethoxylates, sorbitan fatty acid ester ethoxylates, organosilicone based surfactants, ethylene vinyl acetate terpolymers, ethoxylated alkyi aryl phosphate esters and sucrose esters of fatty acids.

The battery separators can be provided in various ways with the additive, agents, fillers, or additives. The additives can for example be applied to the separator when it is finished (i.e. after the extraction) and/or added to the mixture used to produce the separator. According to a preferred embodiment the additive or a solution of the additive is applied to the surface of the separator. 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- 0.0 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, 5.0-1 .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 battery separator 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 separator production.

Another preferred option is to mix the additive or additives into the mixture of thermoplastic polymer and optionally fillers and other additives which is used to produce the battery separators. The additive-containing homogeneous mixture is then formed into a web-shaped material.

In accordance with at least another object of the present invention, there is provided a battery separator with ribs. The separator can have transverse cross-ribs on the opposite face of the separator as the longitudinal ribs. In some embodiments of the present invention, the ribbed separator can have a transverse rib height of at least 0.005 mm, 0.01 mm, 0.025 mm, 0.05 mm, 0.075 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, or 1.0 mm. The ribbed separator can have a transverse rib height between 0.005-1.0 mm, 0.01-0.5 mm, 0.025-0.5 mm, 0.05- 0.5 mm, 0.075-0.5 mm, 0.1-0.5 mm, 0.2-0.4 mm, 0.3-0.5 mm, or 0.4-0.5 mm.

In some embodiments of the present invention, the ribbed separator can have longitudinal rib height of at least 0.005 mm, 0.01 mm, 0.025 mm, 0.05 mm, 0.075 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, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm. The ribbed separator can have a transverse rib height between 0.005-1.5 mm, 0.01-1.0 mm, 0.025-1.0 mm, 0.05-1.0 mm, 0.075-1.0 mm, 0.1-1.0 mm, 0.2-1.0 mm, 0.3-1.0 mm, 0.4-1.0 mm, 0.5-1.0 mm, 0.4-0.8 mm or 0.4-0.6 mm.

In some embodiments of the present invention, the ribbed separator can have a sheet (substrate) thickness of at least 0.005 mm, 0.01 mm, 0.025 mm, 0.05 mm, 0.075 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, or 1.0 mm. The ribbed separator can have a sheet (substrate) thickness between 0.005- 1.0 mm, 0.01-1.0 mm, 0.025-1.0 mm, 0.05-1.0 mm, 0.075-1.0 mm, 0.1-1.0 mm, 0.2-1.0 mm, 0.3-1.0 mm, 0.4-1.0 mm, 0.4-0.9 mm, 0.4-0.8 mm, 0.5-0.8 mm or 0.6-0.8 mm.

In some embodiments of the present invention, the ribbed separator can have overall thickness (positive rib + backweb + negative rib) of at least 0.05 mm, 0.1 mm, 0.25 mm, 0.5 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, or 6.0 mm. The ribbed separator can have a transverse rib height between 0.05-5.0 mm, 0.1-5.0 mm, 0.2-5.0 mm, 0.5-5.0 mm, 1.0-5.0 mm, or 1.0- 4.0 mm.

With regard to at least selected embodiments of the present invention, the ribbed separator can have the following:

1) Transverse Rib Height— preferably between about 0.02 to 0.45 mm, and most preferably between about 0.075 to 0.3 mm.

2) Sheet (Substrate) Thickness— preferably between about 0.065 to 0.75 mm.

3) Overall Thickness (positive rib +backweb +negative rib)— overall thickness of the separator between about 0.10 to 6.0 mm, preferably between about 0.20 to 4.0 mm.

In accordance with at least one embodiment, the separator is made up of an ultrahigh molecular weight polyethylene (UHMWPE) mixed with a processing oil plus additive and precipitated 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 and precipitated silica. The additive can then be applied to the separator via one or more of the techniques described above. In accordance with at least one particular embodiment, the negative cross ribs are rounded mini-ribs and preferably have a 2 to 6 mil radius and a 10 to 50 mil rib spacing.

In accordance with at least selected embodiments, the battery separator includes a porous membrane having a backweb and at least two rows of positive ribs on the positive side of the backweb, and a plurality of negative cross ribs or transverse ribs on the negative side of the backweb. The positive ribs may be straight or wavy, may have a solid portion, and may have a truncated pyramidal shape. The membrane may be selected from the group of polyolefin, rubber, polyvinyl chloride, phenolic, cellulosic, or combinations thereof, and the membrane is preferably a polyolefin material forming a battery separator for a storage battery.

In at least one embodiment, the separator is made of a microporous,

thermoplastic material which is provided with longitudinal positive ribs and transverse negative ribs with the height of at least a majority of the longitudinal ribs being greater than that of the transverse ribs, and the longitudinal and transverse ribs being solid ribs which are formed integrally from the plastic, characterized in that the transverse ribs extend across substantially the entire back width of the separator. The separator back web or sheet thickness may be approximately 0.10 to 0.50 mm, the height of the longitudinal ribs may be 0.3 to 2.0 mm and the height of the transverse ribs may be 0.1 to 0.7 mm, the longitudinal rigidity with 00 mm width may be approximately 5 mJ and the transverse rigidity may be approximately 2.5 mJ, and the total thickness of the separator may be less than 3.5 mm, preferably less than 2.5 mm.

The separators can be be processed to form hybrid envelopes. The hybrid envelope can be formed by forming one or more slits or openings before, during or after, folding the separator sheet in half and bonding edges of the separator sheet together so as to form an envelope. The sides are bonded together using welds or mechanical seals to form seams that bring one side of the separator sheet into contact with another side of the separator sheet. Welds can be accomplished, for instance, using heat or ultrasonic processes. This process results in an envelope shape having a bottom folded edge and two lateral edges.

Separators can be made from polyethylene and can contain V-shaped mini-ribs extending in the transverse or horizontal direction. These ribs are believed to facilitate release of generated gases in the electrolyte by creating channels by which the gas can escape.

Openings can be created in a bottom or lateral edge of the envelope using conventional means. The hybrid envelop can have one or more slits or openings. The length of the openings can at least 1/50^th, 1/25^th, 1/20^th, 1/15^th., 1/10^th, 1/8^th, 1/5^th, 1/4^th, or 1/3^rd the length of the entire edge. The length of the openings can be 1/50^th to 1/3^rd, 1/25^th to 1/3^rd, 1/20^th to 1/3^rd, 1/20^th to 1/4^th, 1 /15^th to 1/4^th, 1/15^th to 1/5^th or 1/10^th to 1/5^th the length of the entire edge. The hybrid envelope can have 1-5, 1-4, 2-4, 2-3 or 2 openings, which may or may not be equally disposed along the length of the bottom edge. A hybrid envelope according to the present invention is depicted in Figiire 1A. It is preferred that no opening is in the comer of the envelope. Without wishing to be bound by theory, it is believe the openings permit enhanced electrolyte flow between electrodes, while still catching debris released from plate.

In accordance with particular examples or embodiments:

Total Separator Thickness:

Range: 0.6mm - 1.6mm; preferably 0.8mm - 1.3mm

Backweb Thickness:

Range: 250 - 500 micron; preferably between 300 - 400 micron

"V" Coating Material:

Surfactant in aqueous solution (water soluble)

Bottom Slits:

Should be at the base of the envelope. Negative Cross Ribs (NCR):

Height of 100 micron, rib spacing of 0.66mm, total separator thickness of

1.05mm, backweb thickness of 300 micron (400 base web) and "V" coating of aqueous surfactant.

Besides lowering water loss and leading to extended battery life, preferred separators are also designed to bring other benefits. With regard to assembly, the separators have the negative cross rib design to maximize bending stiffness and ensure highest productivity. To prevent shorts during high speed assembly and later in life, both separators have superior puncture and oxidation resistance when compared to standard PE separators. Combined with the lowest separator resistance, battery manufacturers are likely to find improved and sustained electrical performance in their batteries with these new separators. Like other PE separators, the preferred products have a micro-porous structure and can be fabricated into pockets or sleeves, which give added protection against side and bottom shorts.

Beside the need for lower water loss, improved resistance to detrimental elements, we believe there is another glaring need primarily found in Asia. In countries where deficits exist between power generation and demand, inverter batteries meet the consumer's need. In such cases, the lead acid battery has filled the need well and will continue to do so. The inverter batteries may be discharged for up to 8 to 16 hours a day and may only receive an occasional charge. In service these inverter batteries may never get fully recharged and may ultimately fail simply due to under charging. These batteries are often returned to the dealer during the warranty period, receive a vigorous recharge and continue on in serviceable life. With this challenging situation in mind, any actions that can improve the charge acceptance or capacity of the battery will provide longer serviceable life.

With the needs of the inverter application in mind, we cycled batteries in the following manner. The batteries were fully discharged and then recharged at a constant voltage ranging from about 13.9 V to 14.4 V (for a 12 volt battery) with a limit current of around 10% of the battery capacity. With such a regime, we hope to recharge the batteries without going into an overcharge situation where vigorous gassing was possible. With no gassing, we realized that the batteries were more likely to see sustained acid stratification and would in the long-term impact the capacity. With such a test regime, we hoped to mimic the real life situations where the batteries struggle to be fully recharged.

With such a test, our goal is to influence battery performance with varied separator designs. As a control, we used separators that were negative wrapped sleeves, standard design positive rib profile and 0.6 mm glass-mat. This is a basic configuration currently being used for inverter batteries. To verify the theory of preventing acid stratification, we simply employed separators with the cross or horizontal rib profile, facing the negative plate.

With the different separators, these batteries were cycled and quickly the negative cross rib is yielding 15% capacity and this difference is sustained with cycling. In previous conferences, we have proposed that the cross rib will break up the boundary layer of concentrated acid that is formed at the plate surface during recharge. Once this boundary layer of acid forms, the heavy acid will collect in the bottom of the cell and distort the charge acceptance. The acid has potential of being mixed during overcharge, when heavy gassing is occurring. However in the inverter application, heavy overcharge is not likely. From the previous chart, batteries utilizing the negative cross rib separator consistently outperformed batteries using separators with standard rib profile. This negative cross rib design, can be included in the preferred product used for dry or wet charge and inverter batteries.

The microporous polymer layer 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, even more preferably ultra high molecular weight polyethylene, i.e. polyethylene having a molecular weight of at least 1 ,000,000, in particular more than 4,000,000, and most preferably 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 precipitated 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 precipitated silica. The microporous polymer layer 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. The preferred filler is dry, finely divided silica. The preferred plasticizer is petroleum oil. 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 microporous polymer layer has an average pore size of less than 1 pm in diameter. Preferably more than 50% of the pores are 0.5 pm or less in diameter. It is especially preferred that at least 90% of the pores have a diameter of less than 0.5 pm. The microporous polymer layer preferably has an average pore size within the range of 0.05 to 0.5 pm, preferably 0.1 to 0.2 pm.

The thickness of the microporous polymer layer is preferably greater than 0.1 mm and less than or equal to 0.6 mm. Preferably, the thickness of the microporous polymer layer is within the range of 0.25 to 0.45 mm and most preferably is about 0.3 mm.

The microporous polyolefin may be provided with one or more additives. One such additive that may be present in the polyolefin is a surfactant. Suitable surfactants include surfactants such as salts of alkyl sulfates; alkylarylsulfonate salts; alkylphenol- alkylene oxide addition products; soaps; alkyl-naphthalene-sulfonate salts; dialkyi esters of sulfo-succinate salts; quaternary amines; block copolymers of ethylene oxide and propylene oxide; and salts of mono and dialkyi 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 aikyl aryl phosphate esters and sucrose esters of fatty acids.

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

R(OR¹)_n(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,

. R is H,— (CH₂)_kCOOM^x+i_/x or— (CH₂)_k— S0₃M^x+i x, preferably H, where k is 1 or 2,

• M is an alkali metal or alkaline-earth metal ion, H⁺ or NH ⁺, 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. Surprisingly it was found that through the use of the compounds of Formula (I) for the production of battery separators, they can be effectively protected against oxidative destruction.

Battery separators are preferred which contain 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 R² 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 R²— [(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 R² 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, OC₃H₆for 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=1 to 4, q=0), fatty alcohol propoxylates (p=0; q=1 to 4) and fatty alcohol alkoxyiates (p=1 to 2; q=1 to 4) ethoxylates of primary alcohols being preferred. The fatty alcohol alkoxyiates 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 difficulty, 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 polyolefin can be provided in various ways with the additive or additives. The additives can for example be applied to the polyolefin when it is finished (i.e. after the extraction) or added to the mixture used to produce the polyolefin.

According to a preferred embodiment the additive or a solution of the additive is applied to the surface of the polyolefin. 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.

In certain embodiments of the invention, the microporous polyolefin separator layer (either having the performance enhancing additive or not) comprises a plurality of acid filling channels or a network of acid filling channels. These acid filling channels are imparted to this microporous polyolefin layer by adding ribs to the layer and/or embossing the layer. When ribs are added to the layer, such ribs may be added to one side or both sides of the polyolefin layer. In some embodiments where ribs are added to both sides, one side may include negative cross-ribs. In some embodiments, the negative cross-ribs may be at an angle relative to the machine direction or transverse direction of the layer. In various embodiments, a pattern of ribs may be added to the layer, and such a pattern may include embattlements, serrations, interrupted ribs, and/or the like. The various patterns of ribs and/or embossed regions (sometimes potentially called calendered regions) include patterns that allow battery acid into the separator, quickly, while simultaneously allowing air to escape out of the separator. In some preferred embodiments, the acid filling channels (or air flow channels) allow air flow while at the same time the ribs or embossments forming the acid filling channels are not so large as to interfere with the separator's overall contact with the electrodes.

The separator may be a PE separator and can be a leaf or sheet, a U fold, a sleeve, or a pocket or envelope, preferably a hybrid envelope.

Home uninterrupted power supply (UPS) and Inverter Batteries are market leaders in India— and will soon be available across the globe.

Flat Plate Deep Cycle Battery:

Features:

• Extra thick plates ensure long life

• Special alloy used - very low maintenance

• Inter partition connection-good voltage profile on discharge

t Sleek appearance in sealed plastic housing

• Good charge acceptance - suitable for frequent power cuts

• Level indicators aid easy maintenance Application:

These batteries are best suitable for high ambient temperature and partial state of charge usage, they are used in various applications like domestic inverters, off grid solar photo voltaic system, home lighting systems, alarm systems, signaling equipments and remote telecom units.

The Key Advantages:

• Medium to very long service life - ranging from 2.5 - 4 years for Deep Cycle design and up to 7 - 10 years for ultra Deep Cycle design. Depending on depth of discharge, frequency of cycling and battery temperatures.

• Compact size with high specific energy. Accomplished by special design of plates containers and separators.

• Very low water topping up frequency. Special alloy plates cause LOW or NO water loss from battery.

Better Design: Better Performance

Thick flat pasted plates with selenium grids and automated vapour; curing process generates suitable proportion of binding crystals in the plates

Preferred Result:

Much longer cycle life that most of the flat plate batteries in the world.

A cycle life of over 500 - 600 cycles under deep discharge conditions.

Examples of embodiments, aspects and/or objects of the present invention include:

Total Separator Thickness

Range 0.6 mm - 2.25 mm, preferable 0.8 - 1.6 mm Backweb Thickness:

Range 250 - 600 micron, preferable 300 to 400 mm

72X (cross rib profile) + V coating (surfactant) + Envelope

72X + V coating

72X + Hybrid envelope (with one or more slits)

V coating + Hybrid envelope

72 (optional cross ribs) + V coating + Hybrid envelope

72X + V coating + Hybrid envelope

The separators of the present invention are particularly useful for flat plate cycling batteries. The separators of the present invention effectively enhance the battery re-chargeability and the backup time. In addition, the separators of the present invention contributes to the reduction of water loss in the battery, lowering the maintenance needs in service. It is expected that batteries having the separators of the present invention will be useful in various applications, such as golf carts, Such batteries will be useful in inverters, golf carts, as well as solar and traction application.

EXAMPLES

The following examples further illustrate at least selected separator embodiments of the instant invention.

To evaluate the battery performance of the disclosed separators, three different battery units were prepared. Flat plate batteries having a charge of 12V 150Ah @ 20 hours were used. The batteries contained 17 plates per cell (8 positive and 9 negative). The antimony content in the grids was 2.5%, and the plates had a mean dry weight of 271.5 grams (positive) and 206.65 grams (negative). The positive plate group weight was 2172 ±1.5 gram/cell, and the negative plate group weight 1860 ±1.5 gram/cell.

The control battery had the following characteristics: a conventional envelop polyethylene separator of 72V profile, back web: 350, OT: 1.25 mm, with 0.9 mm wet glass mat - negative wrap.

The experimental batteries had the following characteristics: a hybrid envelope polyethylene separator of 72X profile, back web: 400 inclusive of the X rib (300+ 00), OT: 1.5 mm, with 1.1 mm wet glass mat (2 layers, 0.8 mm and 0.3 mm) - negative wrap. Some of the experimental batteries further contained the V coating surfactant additive described above. The comparative performance of the batteries are depicted in Figures 2-11.

Disclosed herein are improved separators for valve regulated lead acid batteries. The separators can contain performance enhancing additives, novel hybrid envelope shapes, and/or ribbed surfaces.

The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Additionally, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.

Claims

What is claimed is

1. A battery separator comprising:

a porous sheet having a folded bottom edge and joined lateral edges which form a pocket having an outer surface and an inner surface; wherein the folded bottom edge has one or more openings or slits;

wherein both the outer and inner surfaces of the sheet comprises ribs, wherein the outer and inner ribs do not extend in the same direction.

2. The battery separator according to claim 1 , wherein the separator contains at least one surfactant.

3. The battery separator according to claim 2, wherein the surfactant is a non-ionic surfactant.

4. The battery separator according to claim 3, wherein the non-ionic surfactant comprises one or more polyol fatty acid esters, polyethoxylated esters, polyethoxylated alcohols, alkyi polysaccharides such as alkyi polyglycosides and blends thereof, amine ethoxylates, sorbitan fatty acid ester ethoxylates, organosilicone based surfactants, ethylene vinyl acetate terpolymers, ethoxylated alkyi aryl phosphate esters or sucrose esters of fatty acids.

5. The battery separator according to claim 1 , wherein the outer ribs run parallel to the lateral edges and the inner ribs run perpendicular to the lateral edges, and the outer ribs are larger than the inner ribs.

6. A flooded lead acid battery comprising the separator of claim 5.

7. A flat plate lead acid battery comprising the separator of claim 1.

8. A battery separator comprising:

a porous sheet having a folded bottom edge and joined lateral edges which form a pocket having an outer surface and an inner surface;

9. The battery separator according to claim 8, wherein the separator contains at least one surfactant.

10. The battery separator according to claim 9, wherein the folded bottom edge has one or more openings or slits.

11. A battery separator comprising:

wherein the separator contains at least one surfactant.

12. The battery separator according to claim 1 , wherein both the outer and inner surfaces of the sheet comprises ribs, wherein the outer and inner ribs do not extend in the same direction. 3. A lead acid battery comprising the separator of claim 8.

14. A lead acid battery comprising the separator of claim 11.

15. Novel or improved separators, battery separators, flat plate separators, batteries, cells, and/or methods of manufacture and/or use of such separators, battery separators, flat plate separators, cells, and/or batteries, novel or improved lead acid battery separators for flat plate cycling batteries, flat plate deep cycling batteries, flat plate inverter batteries, flat plate UPS batteries, flat plate home UPS batteries, flat plate long cycle life batteries, deep cycle stationary, traction, inverter, or fork lift batteries, flooded batteries, UPS, ESS, BESS, flat plate cells, and/or improved methods of making and/or using such improved separators, cells, batteries, systems, and/or the like, an improved separator for flat plate stationary batteries and/or improved methods of using such batteries having such improved separators, methods, systems and battery separators for enhancing battery life, reducing water loss, and/or improving uniformity in at least flat plate stationary batteries, an improved separator for flat plate batteries wherein the separator includes performance enhancing additives or coatings, hybrid envelopes, and/or cross rib shapes or profiles, and/or the like as shown or described herein.