WO2021247489A1

WO2021247489A1 - Improved bipolar battery terminal seal and related assemblies and methods

Info

Publication number: WO2021247489A1
Application number: PCT/US2021/035131
Authority: WO
Inventors: Stephen Bryan; Paul J. Melichar
Original assignee: Enersys Delaware Inc.
Priority date: 2020-06-02
Filing date: 2021-06-01
Publication date: 2021-12-09

Abstract

An end frame assembly for a bipolar battery includes: an end frame including first and second opposite surfaces; a terminal including a terminal pad on the first surface of the end frame; a lead sheet on the first surface of the end frame; and at least one track of sealant between the first surface of the end frame and the lead sheet and surrounding the terminal pad.

Description

Improved Bipolar Battery Terminal Seal and Related Assemblies and Methods

Related Applications

[0001] This application claims priority from U.S. Provisional Application No. 63/033,585, filed June 2, 2020, the disclosure of which is incorporated by reference in its entirety.

Background

[0002] In some known bipolar batteries, the terminal seal design relies on the seal generated by injection molding polymer around each battery terminal. The injection molded materials perform two functions: 1) provide mechanical structure to support electrical field terminations (e.g., cables or buss work), and 2) provide a hermetic seal to the outside world to prevent liquid or oxygen leaks around each battery terminal. If the injection molding is not formed properly, the risk of electrochemical leakage increases dramatically as does battery failure. Damage to the injection molded interface may also come from external stress being applied to the battery terminals by external connections (e.g., cables or buss work).

Summary

[0003] Some embodiments of the present invention are directed to an end frame assembly for a bipolar battery, the end frame assembly including: an end frame including first and second opposite surfaces; a terminal including a terminal pad on the first surface of the end frame; a lead sheet on the first surface of the end frame; and at least one track of sealant between the first surface of the end frame and the lead sheet and surrounding the terminal pad.

[0004] In some embodiments, the end frame assembly further includes first and second concentric circular wells surrounding the terminal pad, wherein the at least one track of sealant is at least partially in the first and second wells. The first and second wells may be recessed into the first surface of the end frame.

[0005] In some embodiments, the at least one track of sealant projects outwardly from the first surface of the end frame and forms a circular raised portion of the lead sheet.

[0006] In some embodiments, the sealant includes RTV silicone.

[0007] In some embodiments, the end frame assembly is a positive end frame assembly, the end frame is a positive end frame, and the lead sheet is a positive end frame lead sheet. [0008] In some embodiments, the end frame assembly is a negative end frame assembly, the end frame is a negative end frame, and the lead sheet is a negative end frame lead sheet.

[0009] Some other embodiments of the present invention are directed to a method for assembling an end frame assembly for a bipolar battery, the method including: providing an end frame including first and second opposite surfaces with a terminal pad on the first surface and a well completely surrounding the terminal pad; dispensing sealant into the well; placing a lead sheet on the first surface of the end frame; and compressing the lead sheet and the end frame. [0010] In some embodiments, the placing step and/or compressing step includes spreading the sealant out of the well and forming a raised portion of the lead sheet where the sealant contacts the lead sheet.

[0011] Some other embodiments of the present invention are directed to a bipolar battery including: a positive end frame assembly; a negative end frame assembly; and a plurality of bipole frames between the positive end frame assembly and the negative end frame assembly. Each of the positive end frame assembly and the negative end frame assembly may include: an end frame including first and second opposite surfaces; a terminal including a terminal pad on the first surface of the end frame; a lead sheet on the first surface of the end frame; and at least one track of sealant between the first surface of the end frame and the lead sheet and surrounding the terminal pad.

[0012] Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.

Brief Description of the Drawings

[0013] Figure l is a perspective view of a bipolar battery according to some embodiments of the present invention.

[0014] Figure 2 is another perspective view of the bipolar battery of Figure 1.

[0015] Figure 3 is a schematic sectional view of the bipolar battery of Figure 1.

[0016] Figure 4 is a sectional view of the bipolar battery of Figure 1.

[0017] Figure 5 is a plan view of an end frame according to some embodiments of the present invention. [0018] Figure 6 is an opposite plan view of the end frame of Figure 5.

[0019] Figure 7 is a fragmentary perspective view of the end frame of Figure 5.

[0020] Figure 8 is a plan view of the end frame of Figure 5 with sealant applied thereto.

[0021] Figure 9 is a fragmentary perspective view of the end frame of Figure 8.

[0022] Figure 10 is a fragmentary sectional view of the end frame of Figure 8.

[0023] Figure 11 is a plan view of an end frame assembly including the end frame of Figure 8 and a lead sheet.

[0024] Figure 12 is a fragmentary sectional view of the end frame assembly of Figure 11 illustrating the sealant between the end frame and the lead sheet.

[0025] Figure 13 is a fragmentary perspective view of the end frame assembly of Figure 11.

Detailed Description

[0026] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0027] It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present. Like numbers refer to like elements throughout. As used herein the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0028] In addition, spatially relative terms, such as "under," "below," "lower," "over," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0029] Well-known functions or constructions may not be described in detail for brevity and/or clarity.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

[0031] It is noted that any one or more aspects or features described with respect to one embodiment may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0033] A bipolar battery 10 according to some embodiments is shown in Figures 1-4. The battery 10 includes a positive end frame or plate 12, a negative end frame or plate 14, and a central outer casing 16. The positive end frame 12, the negative end frame 14, and the central outer casing 16 may be referred to herein as the battery casing 18.

[0034] A positive terminal 17 may be at the positive end frame 12 and a negative terminal 19 may be at the negative end frame 14.

[0035] Figure 3 is a simplified schematic of the bipolar battery 10 with some features omitted including the battery casing. The battery 10 includes a stack S of plates, frames, and/or material layers. Starting at the left side of the drawing, the battery includes the positive end frame 12, a positive end frame lead foil or sheet 20, positive active material (PAM) 22, a separator 24, negative active material (NAM) 26, a negative bipole lead foil or sheet 28, and a bipole frame 30. The next cell or module includes a positive bipole lead foil or sheet 32, the PAM 22, the separator 24, the NAM 26, and the negative bipole lead foil or sheet 28. This same sequence is continued in the stack S until, at the right side of the drawing, there is a negative end frame lead foil or sheet 34 and the negative end frame 14.

[0036] Referring to Figures 1 and 4, one or more stabilizing channels 36 may extend through the stack S. The stabilizing channels 36 may be defined by aligned holes or apertures defined in the positive end frame 12, the positive end frame lead sheet 20, the negative end frame 14, the negative end frame lead sheet 34, the bipole frames 30, the negative bipole lead sheets 28, and/or the positive bipole lead sheets 32.

[0037] A stabilizing member 38 may be received in each of the stabilizing channels 36. The stabilizing members 38 may be a fastener such as a bolt, post, or rod. The stabilizing member 38 may be an elongated polymer member that is injected into the stabilizing channels 36. The stabilizing members 38 may provide mechanical stability and strength for the stack S.

[0038] Although eight channels 36 and corresponding stabilizing members 38 are illustrated, it is contemplated that a lesser or greater number of channels and corresponding stabilizing members may be used.

[0039] An electrolyte channel or manifold 40 extends at least partially through the stack S. The electrolyte channel 40 may be defined by aligned holes or apertures defined in the positive end frame lead sheet 20, the negative end frame lead sheet 34, the bipole frames 30, the negative bipole lead sheets 28, and/or the positive bipole lead sheets 32. An electrolyte fill port 42 in fluid communication with the electrolyte channel 40 may be on the positive end frame 12. In other embodiments, the fill port 42 may be positioned differently (e.g., on the negative end frame 14).

[0040] Each separator 24 may include an electrolyte storage reservoir. The electrolyte channel 40 may supply electrolyte to each electrolyte storage reservoir.

[0041] Figures 5-7 illustrate the positive end frame 12 according to some embodiments. The end frame 12 includes a body 44 having first and second opposite primary surfaces 46, 48. The body 44 of the end frame 12 may be formed of a polymer such as ABS.

[0042] One or more bosses 50 may extend outwardly from the first surface 46. The bosses 50 surround stabilization through holes 52 that partially define the stabilization channels 36 described above.

[0043] A boss 54 may extend outwardly from the first surface 46. The boss 54 surrounds an electrolyte through hole 56 that partially defines the electrolyte fill channel 40 described above. [0044] The positive terminal 17 includes a terminal pad 58 on the first surface 46 and a terminal bushing 60 on the second surface 48. The terminal 17 may be formed of an electrically conductive metal such as copper. The terminal 17 may be molded into the end frame body 44. [0045] First and second wells 62, 64 may be on the first surface 46. The wells 62, 64 may have a concentric circle shape and may surround the terminal pad 58. A spacer or spacer region 66 may be disposed between the wells such that the wells 62, 64 are spaced apart from one another. The spacer 66 may be a portion of the first surface 46 of the end frame 12. The wells 62, 64 may be recessed into the first surface 46 of the end frame 12.

[0046] The first well 62 may be defined by first and second sidewalls 62A, 62B and a bottom surface 62C. The second well 64 may be defined by first and second sidewalls 64A, 64B and a bottom surface 64C.

[0047] Although two concentric wells are described herein, it is contemplated that one well or more than two wells may be employed.

[0048] Referring to Figures 7-10, a track of sealant 68 may be dispensed in the first well 62. A track of sealant 70 may be dispensed in the second well 64.

[0049] The sealant may flow freely while being dispensed and cure at room temperature. In some embodiments, the sealant is room temperature vulcanizing (RTV) silicone.

[0050] The tracks of sealant may extend out of or above the wells. That is, the sealant may be dispensed such that that the track extends outward from the bottom surfaces 62C, 64C and is proud of the first surface 46 of the end frame 12. This may help ensure that a sufficient amount of sealant is used for a robust seal and that the sealant is spread over a greater area when the lead sheets are compressed onto the end frame.

[0051] This is illustrated in Figure 10. The sealant 68 is in the well 62 and extends outward from the bottom surface 62C to be proud of first surface 46 of the end frame 12. Similarly, the sealant 70 is in the well 64 and extends outward from the bottom surface 64C to be proud of the first surface 46 of the end frame 12.

[0052] Figure 11 is a plan view of the positive end frame assembly 72. The end frame assembly 72 includes the positive end frame 12 and the positive end frame lead sheet 20 on the first surface 46. A solder joint 74 is between the terminal pad 58 (Figure 5) and the positive end frame lead sheet 20 to provide an electrical connection therebetween.

[0053] It is noted that the negative end frame assembly is substantially similar to the positive end frame assembly described above. The primary difference is the use of the negative end frame lead sheet 34 in place of the positive end frame lead sheet 20.

[0054] Figure 12 is a sectional view showing the wells and sealant after the end frame and lead sheet have been compressed. A portion of the sealant 68 has been pressed out of the well 62 such that a portion of the sealant 68 is on an outer or upper surface 76 of the spacer 66. In addition, a portion of the sealant 68 may be between the first surface 46 of the end frame 12 and the positive end frame lead sheet 20. Similarly, a portion of the sealant 70 has been pressed out of the well 64 such that a portion of the sealant 70 is on the outer or upper surface 76 of the spacer 66. In addition, a portion of the sealant 68 may be between the first surface 46 of the end frame 12 and the positive end frame lead sheet 20.

[0055] Referring to Figures 12 and 13, the sealant may cause the positive end frame lead sheet 20 to include a circular raised portion 78 where the sealant contacts the lead sheet 20. This can provide visual feedback that a robust seal has been formed.

[0056] Referring again to Figures 5 and 7, in some embodiments, a plurality of lead sheet retainer bosses 80 may be on the first surface 46 of the end frame 12. A plurality of the retainer bosses 80 may surround the wells 62, 64. The retainer bosses 80 may extend outwardly away from the first surface 46 of the end frame 12.

[0057] The retainer bosses 80 may help prevent peeling or pulling of the sealant joints during assembly. The retainer bosses perform multiple functions: 1) they keep the lead sheets “coplanar” with the end frame to ensure that the sealant is not disturbed before curing, 2) they allow for immediate manufacturing without requiring the sealant to cure, and 3) they ensure the lead sheet maintains a planar shape in ensuing manufacturing processes. Further, the retainer bosses when heat formed capture the lead sheet and maintain intimate contact between the lead sheet and the end frame at the bosses.

[0058] An example process for assembling the end frame assembly 72 will now be described. Solder paste may be applied to the terminal pad 58 that is molded into the end frame 12. Sealant may be applied to the wells 62, 64 in the end frame 12. The positive end frame lead sheet 20 may be applied to the end frame 12. The lead sheet 20 should clear all bosses when being placed on the end frame 12. The solder paste may be heated and reflowed to electrically connect the lead sheet 20 and the terminal pad 58. The lead sheet 20 may be pressed onto the end frame 12 to form the lead in the sealant area. Heat and pressure may be applied to melt and reform (e.g., flatten) the lead sheet retainer bosses 80 (see Figure 13).

[0059] In some known bipolar batteries, the terminal seal design relies on the seal generated by injection molding polymer around each battery terminal. The injection molded materials perform two functions: 1) provide mechanical structure to support electrical field terminations (e.g., cables or buss work), and 2) provide a hermetic seal to the outside world to prevent liquid or oxygen leaks around each battery terminal. If the injection molding is not formed properly, the risk of electrochemical leakage increases dramatically as does battery failure.

[0060] The present invention eliminates the hermetic sealing requirement of the injection molding process and replaces it with a primary seal. The primary seal includes liquid sealant dispensed into well(s) surrounding each battery terminal. The well(s) contain the sealant material after dispensing and may also ensure a minimum sealant thickness after lead foil compression during the end frame assembly process.

[0061] The current state of the art requires a perfect seal between the injection molded plastic forming the battery end wall and the terminal. The present invention simplifies the injection molding requirements and provides a more robust seal.

[0062] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.

Claims

Claims:

1. An end frame assembly for a bipolar battery, the end frame assembly comprising: an end frame comprising first and second opposite surfaces; a terminal comprising a terminal pad on the first surface of the end frame; a lead sheet on the first surface of the end frame; and at least one track of sealant between the first surface of the end frame and the lead sheet and surrounding the terminal pad.

2. The end frame assembly of claim 1 further comprising first and second concentric circular wells surrounding the terminal pad, wherein the at least one track of sealant is at least partially in the first and second wells.

3. The end frame assembly of claim 2 wherein the first and second wells are recessed into the first surface of the end frame.

4. The end frame assembly of claim 1 wherein the at least one track of sealant projects outwardly from the first surface of the end frame and forms a circular raised portion of the lead sheet.

5. The end frame assembly of claim 1 wherein the sealant comprises RTV silicone.

6. The end frame assembly of claim 1 wherein the end frame assembly is a positive end frame assembly, the end frame is a positive end frame, and the lead sheet is a positive end frame lead sheet.

7. The end frame assembly of claim 1 wherein the end frame assembly is a negative end frame assembly, the end frame is a negative end frame, and the lead sheet is a negative end frame lead sheet.

8. A method for assembling an end frame assembly for a bipolar battery, the method comprising: providing an end frame comprising first and second opposite surfaces with a terminal pad on the first surface and a well completely surrounding the terminal pad; dispensing sealant into the well; placing a lead sheet on the first surface of the end frame; and compressing the lead sheet and the end frame.

9. The method of claim 8 wherein the placing step and/or compressing step comprises spreading the sealant out of the well and forming a raised portion of the lead sheet where the sealant contacts the lead sheet.

10. A bipolar battery comprising: a positive end frame assembly; a negative end frame assembly; and a plurality of bipole frames between the positive end frame assembly and the negative end frame assembly, wherein each of the positive end frame assembly and the negative end frame assembly comprise: an end frame comprising first and second opposite surfaces; a terminal comprising a terminal pad on the first surface of the end frame; a lead sheet on the first surface of the end frame; and at least one track of sealant between the first surface of the end frame and the lead sheet and surrounding the terminal pad.