Patent Application
20130065106
The invention relates to a battery and in particular to a bipolar battery having a series of bipolar battery plates.
A conventional bipolar battery generally includes electrodes having a metallic conductive substrate on which positive active material forms one surface and negative active material forms the opposite surface. The active materials are retained by various means on the metal conductive substrate which is nonconductive to electrolyte ions. The electrodes are arranged in parallel stacked relation to provide a multi-cell battery with electrolyte and separator plates that provide an interface between adjacent electrodes. Conventional mono-polar electrodes, used at the ends of the stack are electrically connected with the output terminals. Most bipolar batteries developed to date have used metallic substrates. Specifically, bipolar lead-acid systems have utilized lead and alloys of lead for this purpose. The use of lead alloys, such as antimony, gives strength to the substrate but causes increased corrosion and gassing.
In most known plates for bipolar batteries, the positive active material, usually in the form of a paste is applied to the metallic conductive substrate on one side while the negative active material is similarly applied to the opposite side. The plates may be contained by a frame which seals the electrolyte between plates so that it cannot migrate through the plate.
In U.S. Pat. No. 4,275,130, a bipolar battery construction 20 is disclosed having a plurality of conductive biplates 21. Each bipolar plate 21 may include a composite, substrate sheet 34 including a continuous phase resin material, which is nonconductive to electrolyte ions. The composite substrate sheet 34 also includes uniformly distributed, randomly dispersed conductive fibers 33 embedded in the material. The binder resin is a synthetic organic resin and may be thermosetting or thermoplastic. The composite substrate sheet 34 has substantially flat opposite side faces 35 which include at their surfaces exposure of portions of the embedded graphite fibers 33. The embedded graphite fibers not only provide electrical conductivity through the substrate sheet 34, but also impart to the thermoplastic material a high degree of stiffness, rigidity, strength and stability. Substrate sheet 34 may be made in any suitable manner such as by thoroughly intermixing the thermoplastic material in particle form with the graphite fibers. The mixture is heated in a mold and then pressure formed into a substrate sheet of selected size and thickness. After the sheet has been cured, the substantially flat side faces 35 may be readily treated or processed, as for example by buffing, to eliminate pinholes or other irregularities in the side faces.
As disclosed, lead stripes are bonded to the composite substrate sheet 34 by known plating processes. On the positive side face 35, the facial areas between lead stripes 38 are covered by a coating of corrosion resistant resin 36 suitably a fluorocarbon resin such as Teflon (polytetrofluoroethylene) which protects against anodic corrosion of the adjacent graphite fibers and polyethylene of the substrate 34. On the negative side face 35, facial areas between lead stripes 37 may be protected by a thin coating of resin impermeable to electrolyte such as a polyethylene coating 36a. In fabrication of the bipolar plate 21 and after the composite substrate sheet 34 has been formed, a thin Teflon sheet may be bonded to the positive side surface 35. Prior to bonding, window like openings corresponding in length and width to the lead stripes are cut. Plating thereafter will bond the lead in stripes 38 to the exposed conductive graphite surfaces on the substrate side face 35. The same fabrication process may be utilized on the negative side face 35 to coat the nonstriped areas with polyethylene or other like material. Plating of the negative stripes may be achieved as with the positive stripes.
A separator plate 23 serves to support the positive active material 24 and the negative active material 25 and may be made of a suitable synthetic organic resin, preferably a thermoplastic material such as microporous polyethylene.
Battery construction 20 includes a plurality of conductive bipolar plates 21, peripheral borders or margins thereof being supported and carried in peripheral insulating casing members 22. Interleaved and arranged between bipolar plates 21 are a plurality of separator plates 23 The separator plates carry positive active material 24 on one side thereof and negative active material 25 on the opposite side thereof. The casing members 22, together with the bipolar plates 21 and separator plates 23, provide chambers 26 for containing electrolyte liquid. At each end of battery construction 20, standard bipolar plates 21 interface with current collecting plates, where 27 is the negative collector plate and 28 is the positive collector plate. Externally of end collectors 27 and 28 are provided pressure members 30 interconnected by rods 31 having threaded portions for drawing the pressure members plates together and applying axial compression to the stacked arrangement of bipolar plates and separator plates.
The bipolar plate 21 is lightweight, rigid, but includes joint lines between the lead stripe edges and protective coatings to resist corrosion and structural deterioration of the substrate. Furthermore, a plating process is required in order to bond the lead stripes 37, 38 to the conductive substrate having graphite fibers. Conductivity is limited by the size and amount type of graphite fibers in the substrate. Additionally, a plurality of bipolar plates 21 and layers are required to sit in separate casing members 22 and an external frame, all of which require further processing steps for more parts. The bipolar battery construction 20 is a complicated design having many layers of materials and substrates assembled in multiple chambers 26 and bodies 43 that are secured together by a complex external frame.
It is an object of the present invention, among other objects, to provide a bipolar battery having a simplified bipolar plate design, wherein the active materials are encased within an insulated frame having a moldable substrate with perforations to improve conductivity between the active materials. Furthermore, the bipolar battery is inexpensive to produce and does not require a complex external frame to support the bipolar plates.
Each bipolar battery plate includes a frame, a substrate, a conductive filler, first and second lead layers, and positive and negative active materials. The substrate includes a plurality of perforations through the substrate, and the substrate is positioned within the frame. The conductive filler seals the perforations. The first lead layer is positioned on one side of the substrate, while the second lead layer is positioned on another side of the substrate. The first and second lead layers are electrically connected to each through the conductive filler sealing the plurality of perforations. The positive active material is positioned on a surface of the first lead layer, while the negative active material is positioned on a surface of the second lead layer.
The invention is explained in more detail below with reference to the Figures shown in the drawings, which illustrate exemplary embodiments of the present invention wherein:
The invention explained in greater detail below with reference to the drawings, wherein like reference numerals refer to the like elements. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the description will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.
With respect to
Now with reference to
In general, the PCB 12, lead foils 14, first active material, 16 and second active material are encased within the frame 11, which provides support and protection for the bipolar plate 10. The PCB 12 having the plurality of perforations 13 is positioned in a center of the frame 11, and the lead foils 14 are positioned on both sides of the PCB 12. If positioning of the lead foils 14 covers the plurality of perforations 13, then lead foils 14 will be modified such that the plurality of perforations 13 in the PCB 12 are exposed. Then, a conductive filler 12a, such as metal alloy (i.e. solder), is positioned in and extending through the plurality of perforations 13. The active materials 16, 18 are then positioned over the lead foils 14 and the conductive filler 12a.
The frame 11 is non-conductive. In the embodiment shown, the frame 11 is a moldable insulative polymer, such as polypropylene, acrylonitrile butadiene styrene (ABS), polycarbonate, copolymers, or polymer blends. Because the frame 11 is moldable, the number of shape and size configurations are abundant, which provides a bipolar plate 10 according to the invention that can be tailored to different uses.
In the embodiment shown, the frame 11 has a generally rectangular shape, which provides support for the PCB 12 when positioned in the frame 11. The frame 11 is a casing for the bipolar plate 10, as well as the bipolar battery 100. The outer surface of the frame 11 is the outer surface of the bipolar plate 10 and bipolar battery 100. The surface of the frame 11 is generally flat, and in particular, along the exterior surfaces of the frame 11. The frame 11 supports itself, as well as the bipolar plate 10 when assembled with the spacers 22 and terminals sections 30, especially when the bipolar plate 10 sits upright against a flat opposing surface.
The frame 11 further includes substrate receiving passageways 11a and material receiving passageways 11b, as shown in
The substrate receiving passageways 11a is a groove used to receive and secure the PCB 12, when the PCB 12 is positioned within the frame 11. Other configurations of substrate receiving passageways 11a are possible, including notches, indentations, recesses or any securing mechanism that secures the PCB 12 within the frame 11. For instance, the PCB 12 could be secured to the frame 11 using a weld or by adhesive, or by a fastener. However, in the embodiment shown, the PCB 12 is secured in the substrate receiving passageways 11a during manufacturing the bipolar plate 10.
Each material receiving passageway 11b is positioned in a substantial center of the frame 11 split from each other by the PCB 12, when the PCB 12 is positioned within the substrate receiving passageways 11a. Furthermore, the lead foils 14 and active materials 16, 18 are encased within an outer surface plane of the frame 11. These pair of cavities are dimensioned to securely receive the lead foils 14 and active materials 16, 18 within the frame 11.
In the embodiment shown, the PCB 12 is a separate substrate with respect to the frame 11, with the PCB 12 being received and secured within the substrate receiving passageways 11a of the frame 11. However, the frame 11 and PCB 12 can be formed together, as a monolithic structure, generally from the same material. During manufacturing, the frame 11 and the PCB 12 are constructed as one piece from the same material. This can be performed through a process such as insert molding, or other known manufacturing methods.
The PCB 12 in the embodiment shown is a known printed circuit board having at least one conductive layer positioned on top of a middle non-conductive layer. In the embodiment shown, there are two conductive layers secured to a middle non-conductive layer using an adhesive such as epoxy resin. The PCB may or may not include existing conductive pathways and/or vias. The plurality of perforations 13 may include these vias or supplemental holes manufactured into the PCB 12. As briefly discussed above, the PCB 12 may be prepared with the frame 11 as a one piece construction.
During manufacturing, the PCB 12 is either insert molded into the substrate receiving passageways 11a, or the frame 11 is over molded over the PCB 12. However, if the frame 11 and the PCB 12 are moldable together, i.e. insert or over molding two pieces together or injection molding one monolithic piece, the manufacturing steps of the bipolar plate 10 can be simplified, with less parts. Furthermore, this process allows the ability to customize the size and shapes of the bipolar plate 10 and bipolar battery 100 according to the invention.
Now with reference back to
Now with reference to
In either case, the perforations 13 can vary in size, shape, or grid pattern, but are large enough that the lead foil 14 can be positioned in and through the perforations 13 and connected to an adjacent lead foil 14. If the perforations 13 are not from the existing vias in the PCB 12, the perforations 13 can be molded or milled into the PCB 12 during manufacturing. The lead foils 14 are shown, being positioned on the both exposed surfaces of the PCB 12, and dimensions to fit within the material receiving passageways 11b of the frame 11. The lead foil 14 is dimensioned to securely fit in the material receiving passageway 11b, such that the frame 11 encases each lead foil 14 positioned on both sides of the PCB 12. The leads foils 14 are mechanically and electrically connected through the conductive filler 12b through the perforations 13, as shown in
In another embodiment, the lead foils 14 may be inserted into the substrate receiving passageways 11, along with the PCB 12 during manufacturing and assembly. The lead foils 14 may be encased within the frame during insert molding, over molding, or similar manufacturing technique where the lead foils 14 and PCB 12 are manufactured within the substrate receiving passageways 11a. The lead foils 14 are positioned on opposite surfaces of the PCB 12 and then either inserted or manufactured within the frame 11. It is possible to apply the lead foils 14 by known plating, vapor deposition, or cold flame spray methods.
It is also possible that the lead foil 14 is a paste having lead, which is positioned along the front and rear surfaces of the PCB 12. The paste is spread across opposite surfaces (i.e. front and rear surfaces) of the PCB 12. The lead foils 14 as paste with the conductive filler 12b connects both sides of the PCB 12 through the perforations 13. The paste would be thick enough to provide connectivity between the pastes on each side, but should not be thicker than the material receiving passageway 11b, considering an active material 16, 18 is also positioned within the material receiving passageway 11b
The conductive filler 12b fills the plurality of perforations in the PCB 12 and the lead foils 14. The conductive filler 12b is a conductive material, such as solder, that flows at a melting temperature and can be applied through the perforations and then overflows each perforation 13 to prepare a conductive head. This conductive head has a larger diameter than a diameter of the perforation 13 and sits on an outer surface of the lead foil 14. In the embodiment shown, the conductive filler has a mushroom shaped conductive head. This provides a larger conductive surface area.
With reference to FIGS. 2 and 5-8, the active materials 16, 18 are shown and positioned on exposed sides of the lead foils 14, facing away from the PCB 12. The first layer of active material 16 is a positive active material paste (PAM) that is applied over one lead foil 14, while a negative active material (NAM) is applied over the other lead foil 14, which is the second active material 18. In the embodiment shown, the positive active material paste (PAM) and the negative active material (NAM) are paste of lead or lead oxide mixed with sulfuric acid, water, fiber, and carbon.
The thickness of the active materials 16, 18 (i.e. NAM and PAM) should not extend outside the material receiving passageway 11b of the frame 11. However, the active materials 16, 18 should cover the conductive filler 12b, and more specifically, the conductive head of the conductive filler 12b. The overall thickness Tm of the PCB 12, 112, lead foils 14, and active materials 16, 18 is less than the thickness Tf of the frame 11.
The frame 11 encases the PCB 12, conductive filler 12b, lead foils 14, and active materials 16, 18. As a result, when assembled the bipolar battery 100 is assembled in stacks of bipolar plates 10, the frame 11 acts as a support and exterior surface for the bipolar battery 100. The number of assembly steps and parts can be minimized.
Now with reference to
The spacer 22 is shown between stacking adjacent bipolar plates 10. The spacer 22 is essentially a casing having similar dimensions as the frame 11 and includes an electrolyte receiving space 22a, as shown in
As shown in
The electrolyte 20 may be a variety of substances, including acid. However, the substance should be a substance that includes free ions that make that substance electrically conductive. The electrolyte 20 may be a solution, a molten material, and/or a solid, which helps create a battery circuit through the electrolyte's ions. In the bipolar battery 100 according to the invention, the active materials 16, 18 provide a reaction that converts chemical energy to electrical energy, and the electrolyte 20 allows the electrical energy to flow from the bipolar plate 10 to another bipolar plate 10, as well as to electrodes 36 of the battery 100.
In the embodiment shown, the electrolyte 20 is an acid that is held in an absorbed glass mat (AGM) 21, as shown in
It is also possible that the glass mat 21 is removed, and an electrolyte 20, such as a gel electrolyte, is free to flow between adjacent active materials 16, 18 between adjacent stacked bipolar plates 10 on either side of the spacer 22.
It is also possible, in other embodiments, that the spacer 22 is an extension of the frame 11. In general, the frame 11 includes a deeper material receiving passageway 11b in order to encase the lead foils 14 and active materials 16, 18, as well as electrolyte 20. Furthermore, if the frame 11 may be dimensioned such that the material receiving passageways 11b of stackable bipolar plates 10 can also hold an fiber glass mat 21 between each other, enclosing an encasing the conductive filler 12a positioned through the PCB 12, the lead foils 14, active materials 16, 18, glass mat 21, and electrolyte 20 within the stacked and sealed bipolar plates 10. The frame 11 may include the electrolyte receiving channel 22b that extends through the frame and into the material receiving passageway 11b. In this embodiment, the bipolar plates 10 can be stacked onto each other and sealed.
Now with reference to
Each terminal section 30 includes an additional layer of active material 32, a terminal plate 34, an electrode 36, and an end plate 38. The end plates 38 are positioned on opposite ends of the stacked bipolar plates 10, with the active material 32, the terminal plate 34 and electrode 36 positioned within the end plate 38.
The active material 32 provides increased electrical flow through the bipolar battery 100, from one terminal section 30 to the other terminal section 30. The active material 32 is made of material that interacts with an adjacent active material 16, 18 from an adjacent bipolar plate 10. Since a spacer 22 and electrolyte 20, as described above, is positioned on each stackable side of the bipolar plates 10, a spacer 22 is positioned between the terminal section 30 and an outside bipolar plate 10. As a result, ions can freely flow through the electrolyte 20 and onto the active material 32 of the terminal section 30.
As shown in
In the embodiment shown, the end plate 38 non-conductive and provides structural support to ends of the bipolar battery 100 according to the invention. The end plate 38 includes a terminal receiving passageway 38a, which is a recess in which the terminal plate 34, electrode 36, and active material 32 are positioned. Additionally, like the material receiving passageway 11b, the terminal receiving passageway 38a provides enough clearance for an amount of electrolyte 20 to be encased with the terminal section 30, and specifically within the material receiving passageway 11b along with the active material 32, terminal plate 34, and electrode 36. In the embodiment shown in
With reference to
The bipolar plate 10 is manufactured and assembled with the PCB 12 secured with the frame 11. The PCB 12 includes perforations 13, and is generally molded with the frame 11, either as a single or separate component. Once the PCB 12 is positioned within the frame 11, the lead foils 14 are positioned with the material receiving passageways 11b of the frame 11 on both exposed surfaces of the PCB 12. The lead foils 14 are electrically connected together through the conductive filler 12a filling the perforations 13. The conductive filler 12a is then spreads out over the exterior surface of the lead foil 14, such that a conductive head is formed, which has a larger diameter than the diameter of the perforation 13 through which the conductive filler 12a is positioned. Then, a first active material 16 is then positioned in the material receiving passageways 11b on one side of the PCB 12, while the second active material 18 is positioned on another side of the substrate within material receiving passageways 11b. The active layer 16, 18 thickness is larger than a thickness of the conductive head of the conductive filler 12a positioned on the exterior surface of the lead foil 14. As a result, the frame 11 encases the substrate 12, lead foils 14, and active materials 16, 18 within surface boundaries of the bipolar plate 10.
The bipolar plates 10 are stacked then next to each other with spacers 22 provided between each stacked bipolar plate Electrolyte 20 is provided in the electrolyte receiving space 22a, which is dimensioned similar to the material receiving passageway 11b of the frame 11. A fiber glass matt 21 can be provided in the electrolyte receiving space 22a, as well, and an electrolyte 20 is provided into the fiber glass matt 21 through the electrolyte receiving channel 22b. The spacers 22 and bipolar plates 10 evenly stack one next to the other, and are subsequently sealed. Since the spacers 22 and stacked bipolar plates 10 include non-conductive outer surfaces, the spacers 22 and frames 11 of the bipolar plates 10 create an outer shell for the bipolar battery 100. The frames 11 of the bipolar plates 10 and spacers 22 can be secured to each other by any method known to the art such that the touching surfaces of the spacers 22 and the frame 11 are secured to each other and sealed. For instance, an adhesive can be used to connect and seal the surfaces together. Additionally, once the terminal sections 30 are assembled, they may be positioned on the stacked bipolar plates 10 and spacers 22, and then sealed in the same manner.
It is also possible, that the end plates 38, the spacer 22, and the frame 11 include securing mechanisms (not shown), such as joint technique or fastener, to connect the pieces of the bipolar battery 100 together. Then a sealant may be applied to provide a seal around the bipolar battery 100, and more specifically, a seal around the connecting end plates 38, spacers 22, and frame 11.
It is also possible, that the bipolar plates 10 are stacked and secured next to each other without a spacer 22. However, the material receiving passageway 11b should be large enough to hold and encase the lead foils 14, active materials 16, 18 and an electrolyte 20, including a fiber glass mat 21, when the stacked bipolar plates 10 are sealed together. Furthermore, the frame 11 should include at least one electrolyte receiving channel 22b positioned in an extension of the frame 11, so that electrolyte 20 can be provided into the material receiving passageway 11b of the frame 11, or allow venting of the electrolyte 20.
The number of bipolar plates 10 used in the bipolar battery 100 is a matter of design choice, dependent upon the size of battery 100 and the electrical potential required. In the embodiment shown, there are at least three bipolar plates 10 stacked next to each other. On opposites ends of the stacked bipolar plates 10 and electrolyte 20 are terminal sections 30, which include a layer of active material 32, a terminal plate 34 and electrode 36, as well as an end plate 38. In the embodiment shown, the outer surfaces of the spacer 22 and the frame 11 are substantially flush with each other when stacked and sealed. This design provides a smooth outer support surface. However, it is possible that irregularities in the surface may exist. For instance, the spacer 22 may be larger than the frame 11; however, the electrolyte receiving space 22a cannot be larger than the frame 11. Additionally, the material receiving passageway 11b cannot be larger than the spacer 22. In either case, it may be difficult to seal the spacer 22 and bipolar plates 10, and the electrolyte 20 could leak from the bipolar battery 100 after assembly and the electrolyte 20 is positioned between adjacent bipolar plates 10.
Furthermore, when the end plate 38 is stacked next to an adjacent spacer 22 and/or frame 11 of an adjacent bipolar plate 10, the outer surfaces of end plate 38, the spacer 22 and the frame 11 should be substantially flush. However, it is possible that irregularities in the surface may exist. For instance, the end plate 38 may be a bit larger than the spacer 22, which may be larger than the frame 11. Nonetheless, terminal receiving passageway 38a should not be larger than the receiving channel 22b or the frame 11. Additionally, the terminal receiving passageway 38a should not be larger than the material receiving passageway 11b or the frame, or the end plate 38 should not be smaller than then the spacer 22. In either case, the electrolyte 20 may leak from the bipolar battery 100 after assembly and the electrolyte 20 is provided between stacked bipolar plates 10. In general, the frame 11 supports the bipolar plate 10, encasing the PCB 12, lead foils 14, conductive filler 12a and active materials 16, 18, as well as electrolyte. When stacked, the bipolar plates 10, with adjacent spacers 20 and stacked terminal sections 30 provide an outer support surface for the bipolar battery 100. This construction provides a bipolar battery 100 having a simplified designed, having fewer manufacturing steps and fewer parts than required in the prior art. Since the frame 10, spacer 22, and end plate 38 are insulative plastic and moldable, the bipolar battery 100 can be customized to accommodate shape and size requirements dependent on electrical potential and use.
In another embodiment, as shown in
The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.
