Bipolar lead-acid battery cells with increased energy density

Abstract

To provide a bipolar lead-acid battery with increased energy density. [Solution] A bipolar lead-acid battery includes a stack of at least two cells arranged in electrical series with the positive face of each cell contacting the negative face of an adjacent cell, each of the cells comprising: a negative electrode including a negative electrode plate and a negative electrode active material; a positive electrode 14 including a positive electrode plate 22 and a positive electrode active material 24, the positive electrode plate including a metal foil with a conductive film 26 thereon; a separator 16 between the electrodes containing an electrolyte; and a cell enclosure surrounding the negative and positive electrodes and the separator and sealing the cell to contain the electrolyte within the cell, the cell enclosure including a plurality of perforations therein that provide electrical connection between adjacent cells.

Description

[Technical field]

[0001] Government Rights in Inventions The U.S. Government has a paid-up license in this invention and has the right, in limited circumstances, to require the patent owner to grant licenses to others on reasonable terms as set forth in W56HZV-16-C-0059 awarded by U.S. Army TARDEC.

[0002] FIELD OF THE DISCLOSURE Embodiments of the present invention relate generally to lead-acid batteries, and more specifically, to bipolar lead-acid batteries having desirable energy density, specific energy, and discharge cycle characteristics. [Background technology]

[0003] Lead-acid batteries of various configurations are well-known power sources for a variety of applications, including start-up lighting ignition (SLI), uninterruptible power supplies (UPS), and motive power. A typical lead-acid battery includes multiple individual cells, each containing a positive and negative electrode, a separator, and an electrolyte (e.g., an acidic aqueous solution). The electrodes include a grid composed primarily of lead and an alloy material that improves mechanical properties, and positive and negative active material pastes are added to the electrode grid to form the positive and negative electrodes. Two important functions of the grid are to mechanically support the active material and to conduct electrical current to and from the active material. Each of the electrodes further includes grid lugs or tabs extending upward therefrom, with the positive electrode lugs connected in parallel via a positive strap and the negative electrode lugs connected in parallel via a negative strap, such that the individual cells are connected in series by these conductive links through inter-cell connectors by welding or other means, from the positive strap to the negative strap of an adjacent cell, or vice versa. The connected cells are then packaged in a cylindrical or prismatic housing to form a multi-cell battery, with the end cell straps terminated to external terminals through the battery cover or case.

[0004] The above construction of a lead-acid battery provides good sealing and reliable operation of the individual cell compartments. However, such construction allocates most of the weight and volume of a multi-cell battery to current transport and packaging, and thus does not fully utilize the energy storage capabilities of the active components of the cells. Furthermore, the inclusion of conductive links (lugs and connecting straps) in the battery increases the internal resistance of the battery. Thus, the weight and volume of the packaging and the high level of internal resistance due to the lugs and straps limit the energy storage capacity and power delivery of the battery based on weight and volume. Furthermore, it is well known that the low active material utilization efficiency, especially at the positive electrode, coupled with the heavy weight of the lead current collectors / substrates, limits the practical specific energy of a lead-acid battery.

[0005] It is therefore desirable to provide a lead-acid battery with desirable energy density, specific energy, and discharge cycle characteristics that can be achieved by the elimination of non-electrochemically functioning metallic lead in the battery, including the lead current collectors / grids, and the elimination of terminals and straps. Elimination of these materials / components allows for an increase in the volume and mass of the lead-acid battery dedicated to available energy storage material, thereby providing a higher energy density lead-acid battery. Summary of the Invention

[0006] According to one aspect of the invention, a lead acid battery wafer cell is provided for forming a bipolar lead acid battery. The lead acid battery wafer cell includes a negative electrode having a negative electrode plate and an active negative electrode material disposed on the negative electrode plate, and a positive electrode having a positive electrode plate and an active positive electrode material disposed on the positive electrode plate. The positive electrode plate includes a titanium substrate with a titanium silicide coating. The lead acid battery wafer cell also includes a separator between the negative electrode and the positive electrode, the separator including an electrolyte for transferring charge between the negative electrode and the positive electrode.

[0007] According to another aspect of the invention, a bipolar lead-acid battery includes a stack of at least two cells arranged in electrical series with the positive face of each cell contacting the negative face of an adjacent cell. Each cell further includes a negative electrode having a negative plate and a negative active material, a positive electrode having a positive plate and a positive active material, a separator between the electrodes including an electrolyte, and a cell enclosure that encloses the negative and positive electrodes and the separator and seals the cell to contain (enclose) the electrolyte within the cell, the cell enclosure including a plurality of perforations therein that provide electrical connection between adjacent cells. The positive plate of each cell includes a metal foil with a conductive film.

[0008] In accordance with yet another aspect of the present invention, a positive electrode of a bipolar lead-acid battery cell includes a positive plate including a titanium substrate having a titanium silicide coating, an active positive electrode material disposed on the positive plate adjacent the titanium silicide coating, and a layer or laminate of lead oxide material between the titanium silicide coating and the active positive electrode material that reduces initial dielectric effects between the positive plate and the active positive electrode material.

[0009] Various other features and advantages will be made apparent from the following detailed description and the drawings. [Brief description of the drawings]

[0010] The drawings illustrate preferred embodiments presently contemplated for carrying out the invention.

[0011] The drawings show:

[0012] [Figure 1] FIG. 1 is a schematic diagram of a lead acid battery wafer cell according to one embodiment of the present invention.

[0013] [Diagram 2] FIG. 2 is a detailed view of a positive electrode included in the wafer cell of FIG. 1 in accordance with an embodiment of the present invention.

[0014] [Diagram 3] FIG. 2 is a detailed view of a negative electrode included in the wafer cell of FIG. 1 according to an embodiment of the present invention.

[0015] [Figure 4] 2 is a side view of an outer polymer layer included in the wafer cell of FIG. 1 in accordance with an embodiment of the present invention.

[0016] [Diagram 5] 2 shows a cross-sectional view of the wafer cell of FIG.

[0017] [Figure 6] 2 illustrates a multi-cell stack of the wafer cells of FIG. 1 forming a lead-acid battery, according to an embodiment of the present invention.

[0018] [Figure 7] FIG. 2 shows a three-dimensional view of a multi-cell stack of wafer cells housed in an outer battery housing, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a bipolar lead-acid battery having desirable energy density, specific energy, and discharge cycle characteristics. In each cell of the battery, non-electrochemically functioning metallic lead is removed and the mass fraction of active energy storage lead is increased to achieve these characteristics. Additionally, an electrically conductive, chemically and electrochemically stable, durable bipolar substrate composite material is provided within the cell to support the positive and negative active materials and provide inter-cell electronic conductivity therebetween.

[0020] A bipolar or pseudo-bipolar lead-acid battery will now be described with reference to the drawings. Referring now to FIG. 1, a schematic diagram of an exemplary lead-acid battery wafer cell 10 (hereinafter "cell 10") forming part of a bipolar or pseudo-bipolar lead-acid battery (hereinafter "lead-acid battery" is provided. Cell 10 includes a negative electrode 12 and a positive electrode 14, which are prevented from direct physical contact with each other by a separator 16, and which are contained between two outer layers, which are a first conductive laminate 18 and a second conductive laminate 20 that are in electrical contact with the negative electrode 12 and the positive electrode 14, respectively. The electrodes 12, 14, the separator 16 between them, and the two outer laminates 18, 20 are each generally flat and in intimate physical contact with adjacent components within cell 10, thereby allowing for the construction of an advantageously thin cell.

[0021] According to an exemplary embodiment, as shown in more detail in FIG. 2, the positive electrode 14 includes a positive plate 22 and a positive active material 24. The positive plate 22 is obtained by forming a conductive film 26 on the surface of a positive substrate 28. According to an exemplary embodiment, the positive substrate 28 is a thin foil made of titanium, and the conductive protective film 26 is made of titanium silicide (TiSi2) (i.e., the titanium silicide layer 26). The pore-free coating of the titanium silicide layer 26 can be applied to the titanium substrate 28 by a chemical vapor deposition (CVD) method according to an exemplary embodiment, but can also be applied by other suitable techniques, such as a dry electrostatic spray process, in which titanium silicide is sprayed as the only component or mixed with a suitable binder (e.g., PVDF), as described in U.S. Patent Application No. 13 / 617,162. According to still other embodiments, the titanium silicide layer 26 can be applied via other powder coating, flame spray, electrochemical deposition, ablation or conversion techniques. According to one embodiment, the titanium substrate 28 has a thickness of 0.1 mm, and the titanium silicide layer 26 on the surface of the titanium substrate 28 in contact with the positive electrode active material 24 is preferably 50 nm or greater.

[0022] According to one embodiment, the positive active material 24 is a plate-shaped active material containing mainly lead dioxide and obtained by preparing an active material paste. The active material paste is obtained by a typical manufacturing method used in the manufacture of lead-acid batteries, such as kneading lead powder, water, and dilute sulfuric acid, and then carrying out chemical conversion and charging, and the active material paste is placed in contact with the surface of the positive plate 22. According to one embodiment, sodium sulfate (Na2SO4) can also be added to the active material paste as a pore former.

[0023] With respect to the interaction between the positive electrode plate 22 and the active material 24, constructing the positive electrode plate 22 from a titanium substrate 28 and a titanium silicide layer 26 results in a dielectric effect existing between the positive electrode plate 22 and the active material 24, which prevents the active material 24 from forming and discharging from the positive electrode 14. That is, the presence of the titanium silicide layer 26 on the titanium substrate 28 adjacent to the active material 24 allows the voltage of the positive electrode 14 to be increased, but no current is output therefrom. Thus, according to an exemplary embodiment, the positive electrode 14 further includes an additional layer or laminate 30 of lead tetroxide (Pb3O4) disposed between the positive electrode plate 22 and the active material 24. The lead tetroxide layer 30 functions to destroy or reduce the initial dielectric effect that exists between the positive electrode active material 24 and the positive electrode plate 22 (i.e., between the active material paste and the titanium silicide layer 26), thereby improving the initial electrical conductivity between the positive electrode active material 24 and the positive electrode plate 22.

[0024] Although lead tetroxide is listed above as an exemplary layer or laminate 30 provided at the interface between the positive electrode active material 24 and the positive electrode plate 22 to promote electrical conductivity between the positive electrode active material 24 and the positive electrode plate 22, it is recognized that other suitable materials may be used, such as, for example, lead dioxide (PbO2), potassium, sodium persulfate, or barium metaplumbate. The inclusion of such a conductivity promoting layer / laminate 30 destroys or reduces the initial dielectric effect that exists between the positive electrode active material 24 and the positive electrode plate 22 (i.e., between the active material paste and the titanium silicide layer 26), thereby improving the initial electrical conductivity between the positive electrode active material 24 and the positive electrode plate 22.

[0025] According to an exemplary embodiment, as shown in more detail in FIG. 3, the negative electrode 12 includes a negative electrode plate 32 and a negative electrode active material 34. The negative electrode plate 32 is obtained by forming a conductive film or coating 36 on a surface of a negative electrode substrate 38. According to an exemplary embodiment, the negative electrode substrate 38 is made of copper and the conductive film / coating 36 is an electroplated pinhole-free lead coating / deposit, thereby providing a pore-free lead-coated copper negative electrode plate 32. In an alternative embodiment, the negative electrode plate 32 may include lead-coated titanium (i.e., a titanium substrate 38 with a lead coating 36), a graphite-coated polymer or a carrier polymer, the coating being applied by a dry electrostatic spray process or the like. According to one embodiment, the lead coating 36 on the surface of the negative electrode substrate 38 in contact with the negative electrode active material 34 is preferably 0.1 mm.

[0026] According to one embodiment, the negative active material 34 is a plate-shaped active material mainly containing sponge-like metallic lead. The plate-shaped active material 34 is obtained by kneading lead powder, water, dilute sulfuric acid, carbon, barium sulfate, and lignin to form an active material paste obtained by a common manufacturing method of a lead-acid battery for chemical conversion and charging, and the active material paste is placed in contact with the lead-plated surface of the negative plate 32. According to one embodiment, sodium sulfate (Na2SO4) can also be added to the active material paste as a pore-forming agent.

[0027] Referring again to FIG. 1, the electrodes 12, 14 can be prevented from direct physical contact with each other by using a separator 16 that extends beyond the edges of the electrodes 12, 14. That is, the separator 16 is interposed between the positive electrode active material 24 and the negative electrode active material 22. The separator 16 is typically made of synthetic resin fibers, such as polyamide or polypropylene fibers. The separator 16 can also be made of materials including, but not limited to, inorganic layers or other suitable separator materials known in the art. The separator 16 is flat and has a porous structure for absorbing and containing the electrolyte or electrolyte solution 40 in the cell 10, the electrolyte 40 typically comprising dilute sulfuric acid as a main component. The positive electrode active material 24, the separator 16, and the negative electrode active material 22 are impregnated with the electrolyte 40.

[0028] The electrodes 12, 14, and separator 16 may be contained within the cell 10 by using a first conductive laminate 18 and a second conductive laminate 20. As shown in the embodiment of FIG. 1, the first laminate 18 is equal and opposite to the second laminate 20. The first laminate 18 includes a first inner metallic layer 42 and a first polymeric outer layer 44. The first polymeric outer layer 44 has at least one perforation 46 or opening therein, exposing the first inner metallic layer 42 and providing a contact point for electrical conduction through the cell 1, as shown in the embodiment of FIGS. 1 and 4 and 5. Similarly, the second laminate 20 includes a second inner metallic layer 48 and a second polymeric outer layer 50. The second polymeric outer layer 50 also has at least one perforation 52 therein, exposing the second inner metallic layer 48 and providing a contact point for electrical conduction through the cell 1. As shown in FIG. 5, the perforations 46, 52 may be aligned with one another to provide optimal electrical conductivity from cell to cell.

[0029] The metal layers 42, 48 of the laminate can be made of any metal material and in a variety of shapes and sizes. For example, the metal layers 42, 48 can be made of thin metal foils the same size as the negative electrode 12 and the positive electrode 14, respectively, and aligned with the respective electrodes as shown in Figures 1 and 5. Multiple layers can also be used. Suitable materials for the metal layers 42, 48 include, but are not limited to, copper, aluminum, steel, silver, nickel, and mixtures thereof, plating materials readily known to those skilled in the art. The thickness of the foil can be as thin as practical, for example, between about 0.0003 inches and about 0.005 inches, depending on the design specifications and to meet the needs thereof.

[0030] To enhance electrical contact, a conductive paste or cement, such as conductive epoxy or other suitable material readily known to those skilled in the art, can be applied between each metal layer and the respective electrode it contacts. A thin layer of conductive cement, 0.0005 to 0.001 inches thick, can serve this purpose.

[0031] The first and second polymer outer layers 44, 50 of the laminate may be made of any suitable polymeric material, including but not limited to nylon polypropylene, polyethylene, polysulfone, polyvinyl chloride and mixtures thereof, or may be composite layers composed of two polymers sandwiched between an intermediate metal layer (e.g., aluminum) or other oxygen barrier layer. The material of the polymer outer layers 44, 50 does not need to be electrically conductive. Thus, an advantage of this feature is that the selection of the material for the polymer outer layers is not limited to such requirements. In one embodiment, each layer 44, 50 is a layer of polypropylene film having a thickness between about 0.001 and about 0.003 inches. Each layer 44, 50 may also be heat sealable and chemically stable in the cell environment.

[0032] The first polymer outer layer 44 may be applied to the first inner metal layer 42 to form the laminate 18 by any suitable sealing mechanism 54, thereby creating a sealed interface. Similarly, the second polymer outer layer 50 may be applied to the second inner metal layer 48 to form the laminate 20 by any suitable sealing mechanism 56, thereby creating a sealed interface. For example, suitable sealing mechanisms 54, 56 include, but are not limited to, the use of binders such as asphalt tar, neoprene, rubber, epoxy, cement, and combinations thereof.

[0033] In one embodiment of the present invention, a potential leakage path for electrolyte from the cell 10 is along the interface between the first or second inner metal layer 42, 48 and the respective first or second outer polymer layer 44, 50 around the edge of the metal layer and to the nearest location of the perforations 46, 52. To create an effective seal, a suitable contact material or sealant that is chemically stable in the cell's electrolyte environment can be applied around the edges of the perforations 46, 52 in an amount sufficient to cover the interface, such as about 0.0003 to 0.001 inches, thereby preventing potential leakage. According to an exemplary embodiment, the sealant includes asphalt tar, although it is recognized that other suitable sealants can be used, including contact cements such as neoprene, rubber, epoxy, cement, and combinations thereof.

[0034] To accommodate the electrodes 12, 14, the separator 16 between the electrodes 12, 14, and the electrolyte 40 within the sealed cell 10, the first and second polymer outer layers 44, 50 of the laminates 18, 20 have a larger physical area around the entire perimeter of the adjacent electrodes than the electrodes 12, 14, as shown in Figures 1 and 5. Furthermore, in one embodiment of the present invention, the first and second polymer outer layers 44, 50, which extend beyond the inner metal layers 42, 48, respectively, are advantageously affixed to one another to provide a seal around the perimeter of the cell 10. Such a seal along the perimeter, which may form a plastic-plastic joint 58, may be accomplished by any suitable known technique, including but not limited to heat sealing or utilizing a cement or filler material that bonds to the material of the polymer outer layers 44, 50. This therefore advantageously results in a sealed enclosure for the cell 10. However, it will be appreciated that the sealed cell 10 may be provided with one or more vents or relief valves to relieve excess pressure built up during deep / fast charging since oxygen and hydrogen gas may be produced during charging by the electrolysis of water.

[0035] Those skilled in the art will also appreciate that the cell 10 can be manufactured in a dry state, a fill port can be provided through one of the laminates 18, 20 for vacuum or pressure filling, and then sealed with an appropriate patch. In this technique, air within the cell can be sucked through a fill port provided in the cell, and the pressure differential forces the electrolyte 40 into the pores of the electrodes 12, 14 and separator 16. Alternatively, the electrodes 12, 14 and separator 16 may be pre-moistened or wetted with a suitable amount of electrolyte 40 before the aforementioned perimeter seal is made to the cell 10. For example, the amount of electrolyte introduced to the cell 10 can fill 60%-90% of the pore volume of the electrodes 12, 14 and separator 16.

[0036] In one embodiment of the present invention, the first conductive laminate 18 is in electrical contact with the exterior surface of the negative electrode 12 through at least one perforation 46, as shown in Figures 1 and 5. Similarly, the second conductive laminate 20 is in electrical contact with the exterior surface of the positive electrode 14 through at least one perforation 52, also shown in Figures 1 and 5. Thus, the laminate design including the perforations 46, 52 advantageously allows electrical contact to be made to the positive and negative sides of the cell 10 from one or more adjacent cells. The size and spacing of the perforations 46, 52 may be determined by multiple design factors related to optimal sealing and current carrying capacity. For example, the placement is to keep the perforations 46, 52 at least 1 / 4 inch from the edge of the foil. The size and spacing of the perforations may be determined by the electrical requirements of the cell.

[0037] The above cell construction offers many advantages over conventional lead-acid cells. It eliminates the non-electrochemically functioning metallic lead in the battery, providing a bipolar cell with a lightweight, leak-free cell package. The inclusion of a titanium biplate coated with a silicide ceramic material (i.e., titanium silicide) in the positive electrode along with a lead-plated copper negative electrode provides a stable, corrosion-resistant base to replace the corrodible external lead (i.e., lead grid) found in typical lead-acid battery electrodes, providing a cell with high energy density and an increased mass fraction of active, energy-storing lead that eliminates the primary wear (failure) mode and aggressive grid corrosion, thereby extending battery life. Intimate contact between the positive plate and the positive active material paste is achieved by the inclusion of a lead tetroxide layer or lead tetroxide laminate in the electrode, which destroys the dielectric barrier that would otherwise exist between the titanium silicide and the positive active material paste.

[0038] Although the exemplary embodiment of the cell above is directed to a bipolar cell having a titanium silicide coated titanium substrate supporting the positive electrode active material and a lead coated copper substrate supporting the negative electrode active material, it is recognized that other substrates and coatings can be used in the bipolar cell, even if they may exhibit reduced performance compared to the above identified materials. By way of example, the positive electrode can include a titanium, copper, aluminum or other metal substrate, or a conductive polymer substrate coated with titanium silicide, tin dioxide or another suitable conductive coating / overcoat, while the negative electrode can include a copper or titanium graphite coated metal substrate, or a supported polymer substrate with or without a graphite coating, where the graphite is mixed with a suitable polymer binder (e.g., PVDF).

[0039] 6, there is shown an embodiment of a multi-cell battery stack 60 (i.e., a lead acid battery 60) of the present invention, which can be made by stacking a plurality of cells 10. The cells 10 are electrically arranged in series with the positive side of each cell 10 contacting the negative side of an adjacent cell 10. In this embodiment, the conductive path through the battery 60 is advantageously from the electrode, through the metal foil layer, through the interior of the metal foil, to the perforations, and then through the perforations to the adjacent cell 10 in the stack 60.

[0040] The end cells of the battery stack 60 may also have metal foil contacts to conduct current from the battery stack to the battery terminals, as described in U.S. Pat. No. 5,393,617. Inter-cell contact, or contact between the end cells and the foil at the piercing points, may also be enhanced by the use of materials such as conductive pastes, cements, or metal filler disks. The compact stack assembly may be held in compression to ensure uniform physical contact between adjacent cells and between the respective layers within each cell. Compression of the stack may be accomplished by rigid end plates with external tie rods wrapped around the stack, as described, for example, in U.S. Pat. No. 5,393,617, or by having internal tie rods that pass through sealed holes provided in the individual cells. The holes may be sealed to prevent leakage and electrical contact between the tie rods and the conductive components of the cells.

[0041] Alternatively, the stack may be housed in an outer battery housing 62, as shown in FIG. 7. To allow for expansion and irregularities of the electrodes in the cell stack 60, the stack 60 may be held in compression by a layer of sponge rubber between one or both of the metal foil contacts and the end plates of the outer housing 62. Springs or gas-filled compressible pads 64 or bladders may be used instead of sponge rubber. Similarly, the cells 60 may be housed in a housing with honeycomb plates for lightweight ridge containment of the cell stack. For example, to reduce the weight of the end plates, ribbed designs or honeycomb sheets well known to those skilled in the art of lightweight structural design may be used. Also, if the cell stack is housed in a sealed outer housing, the outer housing may function to provide stack compression, and the housing may be sealed or vented.

[0042] The cells may each have small vent ports, and the cells may be housed in a sealed container that functions as a battery housing. If the cells are vented, the battery housing may be equipped with a conventional pressure measurement device. Such devices may be pressure gauges, transducers, and / or pressure switches. The pressure measurement device may be used to monitor the battery pressure and adjust the magnitude and duration of the charge current during a charge cycle. Such adjustment of the charge current is referred to herein as charge control. The stack may also include internal tie rods to ensure uniform compression and contact across the faces of the cells. The sealed container may further have a pressure relief valve to vent internal gases. The individual cells 1 may be made according to the description herein, and other battery components such as the pressure gauges discussed above may be made using known methods or obtained from sources known to those skilled in the art.

[0043] To improve heat transfer, additional metal foil layer(s) can be placed between the cells or periodically between the cells, if necessary. Alternatively, the edges of the cells can be extended to improve the thermal interface to the sidewalls of the battery housing. For example, for stable thermal operation, heat generated during the operation of the battery needs to be removed from the surroundings of the battery. To improve internal heat transfer, additional metal foil layers can be placed in the stack, for example adjacent to the metal layer and / or polymer layer, if necessary. Furthermore, the edges of the cells can be extended to contact the sidewalls of the battery housing to ensure thermal contact to the sidewalls.

[0044] Thus, advantageously, embodiments of the present invention provide lead acid battery wafer cells and multi-cell lead acid batteries with desirable energy density, specific energy, and discharge cycle characteristics. The inclusion of an electrically conductive, chemically and electrochemically stable and durable bipolar substrate composite in the cells that provides inter-cell electronic conductivity between cells in the battery as well as supporting the positive and negative active materials allows for an increase in the energy density of lead acid batteries from the previously achievable 30 Wh / kg. At the cell level, embodiments of the present invention provide 70 Wh / kg energy density, up to 200 Wh / L specific energy, and up to 50 deep discharge cycles, while at the module / battery level, scaling up and optimizing the cells can provide 60 Wh / kg energy density, 150 Wh / L specific energy, and 300 deep discharge cycles (in 12V 6T or 24V 4H form factors). It is therefore recognized that the energy density and cell-to-cell interconnectivity achievable with the wafer cell structure (i.e., the materials and cell structure therein) provides approximately double the energy density of existing lead acid batteries / cells, with energy densities of 100 Wh / kg achievable, allowing a lead acid battery according to the present invention to compete with the energy density of lithium ion batteries.

[0045] Thus, according to one embodiment of the present invention, there is provided a lead acid battery wafer cell for forming a bipolar lead acid battery. The lead acid battery wafer cell includes a negative electrode having a negative electrode plate and an active negative electrode material disposed on the negative electrode plate, and a positive electrode having a positive electrode plate and an active positive electrode material disposed on the positive electrode plate. The positive electrode plate includes a titanium substrate having a titanium silicide coating. The lead acid battery wafer cell also includes a separator between the negative electrode and the positive electrode, the separator including an electrolyte for transferring charge between the negative electrode and the positive electrode.

[0046] According to another embodiment of the invention, a bipolar lead acid battery includes a stack of at least two cells arranged in electrical series with the positive face of each cell contacting the negative face of an adjacent cell. Each cell further includes a negative electrode having a negative plate and a negative active material, a positive electrode having a positive plate and a positive active material, a separator between the electrodes, the separator including an electrolyte, and a cell enclosure that surrounds the negative and positive electrodes and the separator and seals the cell to contain (enclose) the electrolyte within the cell, the cell enclosure including a plurality of perforations therein that provide electrical connection between adjacent cells. The positive plate of each cell includes a metal foil with a conductive film thereon.

[0047] In accordance with yet another embodiment of the present invention, a positive electrode of a bipolar lead-acid battery cell includes a positive plate including a titanium substrate having a titanium silicide coating thereon, an active positive electrode material disposed on the positive plate adjacent the titanium silicide coating, and a layer or laminate of lead oxide material between the titanium silicide coating and the active positive electrode material that reduces initial dielectric effects between the positive plate and the active positive electrode material.

[0048] This written description uses examples to disclose the invention, including the best mode, and also provides further examples. Making and using any device or system, and performing any incorporated method The patentable scope of the invention is defined by the appended claims. The scope of the invention is defined by the scope of the claims and may include other examples that occur to those skilled in the art. If the claimed invention has structural elements that are not different from the claim language or If the invention contains substantially the same structural elements, it is intended to be within the scope of the claims. The figure shows. DISCLOSURE OF THEINVENTION (Item 1) A lead-acid battery wafer cell for forming a bipolar lead-acid battery, the lead-acid battery wafer cell comprising: A negative electrode, A negative electrode plate; a negative electrode active material disposed on the negative electrode plate; a negative electrode comprising: A positive electrode, A positive electrode plate; A positive electrode active material disposed on the positive electrode plate; a positive electrode comprising: a separator between the negative electrode and the positive electrode, the separator including an electrolyte for transferring charge between the negative electrode and the positive electrode; Including, The positive plate includes a titanium substrate having a titanium silicide coating thereon. Lead acid battery wafer cell. (Item 2) the positive electrode further comprises an additional layer or laminate of a conductivity promoting material between the positive plate and the positive active material that reduces an initial dielectric effect between the positive plate and the positive active material; 2. The lead acid battery wafer cell according to item 1. (Item 3) The conductivity enhancing material is lead tetroxide (Pb 3 O 4 ), lead dioxide (PbO 2 ), potassium, sodium persulfate, and barium plumbate; Item 3. The lead acid battery wafer cell according to item 2. (Item 4) The negative plate comprises a lead-coated metal substrate; 2. The lead acid battery wafer cell according to item 1. (Item 5) The metal substrate comprises copper. 5. The lead acid battery wafer cell according to item 4. (Item 6) The lead acid battery wafer cell has an energy density of 60 Wh / kg or more. 2. The lead acid battery wafer cell according to item 1. (Item 7) a first conductive laminate including a first inner metallic layer and a first outer polymeric layer, the first outer polymeric layer having at least one perforation therein to expose the first inner metallic layer, the first conductive laminate being in electrical contact with an outer surface of the negative electrode; a second conductive laminate including a second inner metallic layer and a second outer polymeric layer, the second outer polymeric layer having at least one perforation therein to expose the second inner metallic layer, the second conductive laminate being in electrical contact with an outer surface of the positive electrode; Further comprising: the first and second laminates are peripherally sealed together to form an enclosure containing the negative and positive electrodes, the separator, and the electrolyte. 2. The lead acid battery wafer cell according to item 1. (Item 8) further comprising a layer of asphalt tar disposed between the first polymeric outer layer and the first inner metal layer, and between the second polymeric outer layer and the second inner metal layer to provide a sealed interface. 8. The lead acid battery wafer cell according to item 7. (Item 9) said first and second outer polymeric layers each being made of a polymeric material selected from polypropylene, polyethylene, polysulfone, polyvinyl chloride, and mixtures thereof; 8. The lead acid battery wafer cell according to item 7. (Item 10) each of the negative electrode, the positive electrode, the separator, and the first and second laminates is substantially flat; 8. The lead acid battery wafer cell according to item 7. (Item 11) a stack of at least two cells arranged in electrical series with the positive face of each cell in contact with the negative face of an adjacent cell, each of said cells comprising: a negative electrode including a negative electrode plate and a negative electrode active material; a positive electrode including a positive electrode plate and a positive electrode active material; a separator between the electrodes, the separator comprising an electrolyte; a cell enclosure surrounding the negative and positive electrodes and the separator and sealing the cell to contain the electrolyte within the cell, the cell enclosure including a plurality of perforations therein providing electrical connections between adjacent cells; Including, The positive electrode plate includes a metal foil having a conductive film thereon. Bipolar lead-acid battery. (Item 12) Item 12. The bipolar lead-acid battery of item 11, wherein the metal foil comprises a titanium foil and the conductive film comprises a titanium silicide coating. (Item 13) the positive electrode further comprises an additional layer or laminate of a conductivity promoting material between the positive plate and the positive active material that reduces an initial dielectric effect between the positive plate and the positive active material; Item 12. The bipolar lead-acid battery according to item 11. (Item 14) The conductivity enhancing material is lead tetroxide (Pb 3 O 4 ), lead dioxide (PbO 2 ), potassium, sodium persulfate, and barium plumbate; Item 14. The bipolar lead-acid battery according to item 13. (Item 15) The negative plate comprises a lead-coated copper substrate; Item 12. The bipolar lead-acid battery according to item 11. (Item 16) Item 12. The bipolar lead-acid battery according to item 11, wherein the bipolar lead-acid battery has an energy density of 60 Wh / kg or more and a specific energy of 150 Wh / L or more, and is operable for 300 deep discharge cycles. (Item 17) The cell enclosure comprises: a first conductive laminate including a first inner metallic layer and a first outer polymeric layer, the first outer polymeric layer having at least one perforation therein to expose the first inner metallic layer, the first conductive laminate being in electrical contact with an outer surface of the negative electrode; a second conductive laminate including a second inner metallic layer and a second outer polymeric layer, the second outer polymeric layer having at least one perforation therein to expose the second inner metallic layer, the second conductive laminate being in electrical contact with an outer surface of the positive electrode; Including, the first and second laminates are peripherally sealed together to form the cell enclosure. Item 12. The bipolar lead-acid battery according to item 11. (Item 18) and further comprising a layer of asphalt tar disposed between the first polymeric outer layer and the first inner metal layer, and between the second polymeric outer layer and the second inner metal layer, providing a sealed interface therebetween. Item 18. The bipolar lead-acid battery according to item 17. (Item 19) a battery housing containing the stack of at least two cells, the stack of at least two cells being held in a compressed state within the battery housing; Item 12. The bipolar lead-acid battery according to item 11. (Item 20) A positive electrode of a bipolar lead-acid battery cell, the positive electrode comprising: a positive electrode plate comprising a titanium substrate having a titanium silicide coating thereon; a positive electrode active material disposed on the positive electrode plate adjacent the titanium silicide coating; a layer or laminate of lead oxide material between the titanium silicide coating and the positive active material, which reduces the initial dielectric effect between the positive plate and the positive active material; A positive electrode comprising: (Item 21) The lead oxide material is lead tetroxide (Pb 3 O 4 ) and lead dioxide (PbO 2 ), 21. The positive electrode according to item 20.

Claims

1. a stack of at least two cells arranged in electrical series with the positive face of each cell in contact with the negative face of an adjacent cell, each of said cells comprising: a negative electrode including a negative electrode plate and a negative electrode active material; a positive electrode comprising a positive plate and a positive electrode active material, the positive plate comprising a metal foil having a conductive film thereon; a separator between the electrodes, the separator comprising an electrolyte; a cell enclosure surrounding the negative and positive electrodes and the separator and sealing the cell to contain the electrolyte within the cell, the cell enclosure including a plurality of perforations therein providing electrical connections between adjacent cells; A bipolar lead-acid battery comprising:

2. 2. The bipolar lead-acid battery of claim 1, wherein the metal foil comprises titanium foil and the conductive film comprises a titanium silicide coating.

3. 3. The bipolar lead-acid battery of claim 2, wherein the titanium silicide coating is a pore-free titanium silicide coating.

4. 4. The bipolar lead-acid battery of claim 3, wherein said positive plate consists solely of said titanium foil and said pore-free titanium silicide coating.

5. 2. The bipolar lead acid battery of claim 1, wherein the positive electrode further comprises an additional layer or lamination of a conductivity promoting material between the positive plate and the positive active material that reduces the initial electrical conductivity between the positive plate and the positive active material.

6. 6. The bipolar lead-acid battery of claim 5, wherein the conductivity facilitating material comprises one or more of lead tetroxide, lead dioxide, potassium, sodium persulfate, and barium plumbate.

7. the positive electrode active material of the positive electrode plate includes a layer of active material paste; the additional layer or lamination of the conductive facilitating material functions to destroy or reduce the initial electrical conductivity between the layer of active material paste and the conductive film; 6. The bipolar lead-acid battery according to claim 5.

8. 10. The bipolar lead-acid battery of claim 1, wherein the negative plate comprises a lead-coated metal substrate.

9. 9. The bipolar lead-acid battery of claim 8, wherein the lead-coated metal substrate comprises a lead-coated copper substrate.

10. 2. The bipolar lead-acid battery of claim 1, wherein the bipolar lead-acid battery has an energy density of 60 Wh / kg or more and a specific energy of 150 Wh / L or more, and is operable for a minimum of 300 deep discharge cycles.

11. The cell enclosure comprises: a first conductive laminate including a first inner metallic layer and a first outer polymeric layer, said first outer polymeric layer having at least one perforation therein to expose said first inner metallic layer, said first conductive laminate being in electrical contact with an outer surface of said negative electrode; a second conductive laminate including a second inner metallic layer and a second outer polymeric layer, the second outer polymeric layer having at least one perforation therein to expose the second inner metallic layer, the second conductive laminate being in electrical contact with an outer surface of the positive electrode; Including, the first and second laminates are peripherally sealed together to form the cell enclosure.

2. The bipolar lead-acid battery according to claim 1.

12. 12. The bipolar lead-acid battery of claim 11, further comprising a layer of asphalt tar disposed between the first polymer outer layer and the first inner metallic layer, and between the second polymer outer layer and the second inner metallic layer, providing a sealed interface therebetween.

13. 12. The bipolar lead-acid battery of claim 11, wherein the first and second outer polymeric layers are each made of a polymeric material selected from polypropylene, polyethylene, polysulfone, polyvinyl chloride, and mixtures thereof.

14. 12. The bipolar lead-acid battery of claim 11, wherein each of the negative electrode, positive electrode, separator, first conductive laminate, and second conductive laminate is substantially flat.

15. 10. The bipolar lead acid battery of claim 1, further comprising a battery housing containing the stack of at least two cells, the stack of at least two cells being held in compression within the battery housing.

16. A lead-acid battery wafer cell for forming a bipolar lead-acid battery, the lead-acid battery wafer cell comprising: A negative electrode, A negative electrode plate; a negative electrode active material disposed on the negative electrode plate; a negative electrode comprising: A positive electrode, a positive electrode plate including a metal foil having a conductive film thereon; A positive electrode active material disposed on the positive electrode plate; a positive electrode comprising: a separator between the negative electrode and the positive electrode, the separator including an electrolyte for transferring charge between the negative electrode and the positive electrode; a cell enclosure that encloses the negative electrode, the positive electrode and the separator, seals the cell and contains the electrolyte within the cell; Equipped with A lead acid battery wafer cell, wherein the cell enclosure includes a plurality of perforations therein providing electrical connection to at least one adjacent lead acid battery wafer cell.

17. 17. The lead acid battery wafer cell of claim 16, wherein said conductive film is non-porous.

18. The lead acid battery wafer cell of claim 16, wherein the plurality of perforations provide electrical connection to two adjacent lead acid battery wafer cells.

19. 17. The lead acid battery wafer cell of claim 16, wherein the positive electrode further comprises an additional layer or lamination of a conductivity promoting material between the positive plate and the active positive electrode material that reduces the initial electrical conductivity between the positive plate and the active positive electrode material.

20. The cell enclosure comprises: a first conductive laminate including a first inner metallic layer and a first outer polymeric layer, said first outer polymeric layer having at least one perforation therein to expose said first inner metallic layer, said first conductive laminate being in electrical contact with an outer surface of said negative electrode; a second conductive laminate including a second inner metallic layer and a second outer polymeric layer, the second outer polymeric layer having at least one perforation therein to expose the second inner metallic layer, the second conductive laminate being in electrical contact with an outer surface of the positive electrode; Including, the first and second laminates are peripherally sealed together to form the cell enclosure.

17. The lead acid battery wafer cell of claim 16.

Images