CA1185774A - Method for joining metal to graphite - Google Patents
Method for joining metal to graphiteInfo
- Publication number
- CA1185774A CA1185774A CA000389142A CA389142A CA1185774A CA 1185774 A CA1185774 A CA 1185774A CA 000389142 A CA000389142 A CA 000389142A CA 389142 A CA389142 A CA 389142A CA 1185774 A CA1185774 A CA 1185774A
- Authority
- CA
- Canada
- Prior art keywords
- graphite
- openings
- metal
- members
- metal members
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/16—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded
- B23K11/20—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded of different metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
- H01M50/534—Electrode connections inside a battery casing characterised by the material of the leads or tabs
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
- H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
ABSTRACT
A method of joining two metal members to a graphite member to form a structure having a low transition resistance is described. The method includes the steps of providing a plurality of openings in the graphite mem-ber, interposing the graphite member between the two metal members and positioning the metal members to cover the openings in the graphite member, and resistance spot welding the metal members to the graphite member at the openings in the graphite member. This method is advan-tageous in forming a bus-bar connection between a pair of opposite polarity graphite electrodes in an electro-chemical cell stack, such as a zinc-chloride battery. In this particular application, it is preferred that titanium be used for the metal members.
A method of joining two metal members to a graphite member to form a structure having a low transition resistance is described. The method includes the steps of providing a plurality of openings in the graphite mem-ber, interposing the graphite member between the two metal members and positioning the metal members to cover the openings in the graphite member, and resistance spot welding the metal members to the graphite member at the openings in the graphite member. This method is advan-tageous in forming a bus-bar connection between a pair of opposite polarity graphite electrodes in an electro-chemical cell stack, such as a zinc-chloride battery. In this particular application, it is preferred that titanium be used for the metal members.
Description
7~ .
A METIIOD OF JOINING METAL TO GRAPHITE
BACKGROUND AND SU~I~lARY OF THE INVENTION
3 The present invention relates generally to joining me~al to graphite, and particularly to forming a bus bar connection be~ween a pair of graphite elec~rodes for use in an electrochemical cell.
Graphite is used in many indus~rial fields, in-cluding chemical, electrical, metallurgical, electrochemical, nuclear, and rocXet fields. In several of these areas of manufacture~ it i5 desirable to join metal to graphite.
In the field of electrochemistry, graphite is widely used as an electrode material due to its electrical and thermal characteris~ics, and because it is one of the mos~ inert materials with respect to chemical reactions. Furthermore, in this field, suitable metals having low electrical re-sistivity are used as a bus-bar material for joining two or more graphite electrodes together. In ~his particular application, it is important to achieve a low transition ; or contac~ res;stance between the metal bus-bar and grapllite electrodes being joined in order to minimize voltaic losses.
One such electroche~ical application is ~he zinc-chloride battery, where graphite is employed for both the positive and negative electrodes. During the charging of the battery, zinc metal is electrodeposited on the negative or zinc electrode and chlorine gas is generated at the positi~e or chlorine electrode from an aqueous ~inc-chloride electrolyte. During the discharging of the battery, the reactions are reversed to generate electriclty .
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from the terminals of the battery. The zinc electrode is constructed from dense or fine grained graphi~e, and the chlorine electrode is constructed from a liquid permeable porous graphite.
One technique of joining metal to graphite is described in U.S. Patent No. 4,100,332, issued on July 11, 1978, entitled "Comb Type Bipolar Electrode Elements And Bat~ery S~acks Thereof".
In this patent, it is taught to provide for a press or interference fit between the graphite electrodes and the graphite or valve metal bus-bar wall. Accordingly, the electrodes are constructed slightly thicker than the ~rooves in the bus-bar, so that when pressed in they may be retained by a pressure fit. It is also stated that the electrodes may be connected to the bus-bar by c~enting, plasma spraying a~ the point of contac~, or welding.
Another zinc-chloride battery stack design is described in U.S. Patent No. 4,071,660, issued January 31, 1978, enti~led "Electrode For A Zinc-Chloride Ba~tery And Batteries Containing The Same".
In this patent, it is taught to provide an interference fit between graphite electrodes and a titanium bus-bar in one instance, and acemented connection between graphite electrodes and a ~itanium -bus-bar in an~ther instance. It should also be noted that in addition to the cement and interference fit con-nections, bolt connections have also been employed to join metal to graphite.
The present invention provides a no~el method of joining metal to graphite which results in a low
A METIIOD OF JOINING METAL TO GRAPHITE
BACKGROUND AND SU~I~lARY OF THE INVENTION
3 The present invention relates generally to joining me~al to graphite, and particularly to forming a bus bar connection be~ween a pair of graphite elec~rodes for use in an electrochemical cell.
Graphite is used in many indus~rial fields, in-cluding chemical, electrical, metallurgical, electrochemical, nuclear, and rocXet fields. In several of these areas of manufacture~ it i5 desirable to join metal to graphite.
In the field of electrochemistry, graphite is widely used as an electrode material due to its electrical and thermal characteris~ics, and because it is one of the mos~ inert materials with respect to chemical reactions. Furthermore, in this field, suitable metals having low electrical re-sistivity are used as a bus-bar material for joining two or more graphite electrodes together. In ~his particular application, it is important to achieve a low transition ; or contac~ res;stance between the metal bus-bar and grapllite electrodes being joined in order to minimize voltaic losses.
One such electroche~ical application is ~he zinc-chloride battery, where graphite is employed for both the positive and negative electrodes. During the charging of the battery, zinc metal is electrodeposited on the negative or zinc electrode and chlorine gas is generated at the positi~e or chlorine electrode from an aqueous ~inc-chloride electrolyte. During the discharging of the battery, the reactions are reversed to generate electriclty .
.. ,,',~ ' , .
.' ' ';` , ' ,~ ~
........ __ , r ~1~35~79~
from the terminals of the battery. The zinc electrode is constructed from dense or fine grained graphi~e, and the chlorine electrode is constructed from a liquid permeable porous graphite.
One technique of joining metal to graphite is described in U.S. Patent No. 4,100,332, issued on July 11, 1978, entitled "Comb Type Bipolar Electrode Elements And Bat~ery S~acks Thereof".
In this patent, it is taught to provide for a press or interference fit between the graphite electrodes and the graphite or valve metal bus-bar wall. Accordingly, the electrodes are constructed slightly thicker than the ~rooves in the bus-bar, so that when pressed in they may be retained by a pressure fit. It is also stated that the electrodes may be connected to the bus-bar by c~enting, plasma spraying a~ the point of contac~, or welding.
Another zinc-chloride battery stack design is described in U.S. Patent No. 4,071,660, issued January 31, 1978, enti~led "Electrode For A Zinc-Chloride Ba~tery And Batteries Containing The Same".
In this patent, it is taught to provide an interference fit between graphite electrodes and a titanium bus-bar in one instance, and acemented connection between graphite electrodes and a ~itanium -bus-bar in an~ther instance. It should also be noted that in addition to the cement and interference fit con-nections, bolt connections have also been employed to join metal to graphite.
The present invention provides a no~el method of joining metal to graphite which results in a low
2-8~7~7~
(,) transition or contact resistance. Particularly, the method comprises: providing a plurality of openings in a graphite member to be joined, interposing the graphite member between two metal members and positioning the metal S members to cover the openings in the graphite member, and resistance spot welding the metal members to the graphite member at the openings in the graphite member. The re-sistance spot welding may be accomplished with one or more pairs of opposing welding electrodes for a sequential or simultaneous spot welding at the openings in the graphite member. The welding electrodes are used to apply a pre-determined amount of pressure to the metal members at the opening selected for spot welding, and sufficient electrical current is passed through the welding eiectrodes to spot weld the metal members together through the opening.
During the resistance spot welding, a~ least a portion of the metal from the two metal members flows into the opening of the graphite member under the pressure of the wel~ing electrodes, and the gap between the metal mcmbers is bridged. As the metal cools, it contracts thereby exerting a force drawing the two metal members together to achieve a good electrical contact with the graphite member. Some penetration of the metal into the pores of the graphite member also occurs.
In the zinc-chloride battery application, it is preferred that titanium or tantalum be used for the metal members. These particular metals have a relatively low electrical resistivity compared to graphite, and are generally chemically resistant or inert to the zinc-chloride ~0 electrolyte and other chemical entities with which they
(,) transition or contact resistance. Particularly, the method comprises: providing a plurality of openings in a graphite member to be joined, interposing the graphite member between two metal members and positioning the metal S members to cover the openings in the graphite member, and resistance spot welding the metal members to the graphite member at the openings in the graphite member. The re-sistance spot welding may be accomplished with one or more pairs of opposing welding electrodes for a sequential or simultaneous spot welding at the openings in the graphite member. The welding electrodes are used to apply a pre-determined amount of pressure to the metal members at the opening selected for spot welding, and sufficient electrical current is passed through the welding eiectrodes to spot weld the metal members together through the opening.
During the resistance spot welding, a~ least a portion of the metal from the two metal members flows into the opening of the graphite member under the pressure of the wel~ing electrodes, and the gap between the metal mcmbers is bridged. As the metal cools, it contracts thereby exerting a force drawing the two metal members together to achieve a good electrical contact with the graphite member. Some penetration of the metal into the pores of the graphite member also occurs.
In the zinc-chloride battery application, it is preferred that titanium or tantalum be used for the metal members. These particular metals have a relatively low electrical resistivity compared to graphite, and are generally chemically resistant or inert to the zinc-chloride ~0 electrolyte and other chemical entities with which they
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will come into contact. Although titanium is extremely reactive above 1000F in an oxygen and nitrogen atmosphere, it has been found that no special atmospheric shielding is required for the resistance spot welding.
Other features and advantages of the present invention will become apparent in view of the drawings and the following detailed description of the preferred embodiment.
BRIEF DESCRIP~ION OF THE DRAl~INGS
Figure l is a perspective view of a section of a zinc-chloride bat~ery stack constructed in accordance with the present invention.
Figure 2 is a perspective view of an electrode pair forming a portion of the battery stack of Figure l.
Figure 3 is a front elevation assembly view of the electrode pair of Figure 2.
Figure 4 is a schematic representation of an arrangemellt for resistance spot welding metal to graphite.
DETAILED DESCRIPTION OF THE PREFERRED E~BODIMENT
Referring to Figure 1, a perspective view of a section of a zinc-chloride battery stack 10 is shown.
Battery stack 10 is generally comprised of a plurality of electrode pairs 12, shown individually in Figure 2, and a plastic frame 14. Each electrode pair 12 ls comprised of a zinc electrode 16, a chlorine electrode structure 18, and a bus-bar 20 coupling the zinc electrode to the chlorine electrode structure. Chlorine electrode structure 18 includes a pair of chlorine electrode members 22 and ~5~
24 joined to a graphite frame 26. Zinc electrode 16 is pre-fexably constructed from a dense or fine yrained graphite, as exemplified by Union Carbide Corp. *ATJ or *EBP graphi-tes.
The zinc electrode also includes a tab portion 2~ projecting from the top of the electrode to provide a surface area for connection to bus-bar 20.
Chlorine electrode members 22 and 24 are preferably constructed from liquid-permeable but gas-impermeable porous graphite, as exemplified by Union Carbide Corp. *PG~60 or *Airco Speer 37-G graphite. Graphite frame 26 is also prefer-ably constructed from dense graphite, and serves to separate the t~o chlorine electrode members and acts as an electrical conduit. This graphite frame is comprised of top leg 26a and a side leg 26b at each end of the chlorine electrode structure.
The graphite frame also includes a tab portion 29 which is used to electrically connect chlorine electrode structure 18 to the bus-bar 20. A detailed description of the connection between electrode me~bers 22 and 24 and the graphite frame 26 is set forth in a co-filed Canadian Patent Application ~0 Serlal No. 389,122, filed October 30, 1981, entitled "A ~ethod Of Joining Graphite To Graphite", assigned to the assignee of the present inyention.
Plastic frame 14 is preferably constructed from thermoplastic resins which are chemically resistant to ~he zinc-chloride battery environment, as exemplified by General Tire & Rubber Corp, *Boltron polyvinyl chloride (4008-2124), Dupont *Teflon (tetrafluori~naded ethylene), and Pennwalt *Kynar (polyvinylidene fluoride). Plastic frame 14 serves -to align and separate electrode pairs 12, *-Trade marks~
mab/,4,4~, . . .
and provides a means to convey the electrolyte to chlorine electrode structure 18. The chlorine electrode structure is open at the bottom between electrode members 22 and 24 to receive electrolyte, as graphite frame 26 does not in-clude a bottom leg.
Bus-bar 20 preferably constructed from titanium r or tantalum due to their mechanical strength, electrical conductivity, and resistance to chemical corrosion in the zinc-chloride battery environment. This bus-bar serves as a curren~ collector and connects adjacent cells of battery stac~ 10 electrically in series. Current sharing is facilitated between the cells arranged in parallel by a clip-on titanium s~rip 30, which is used to connect bus-bars of the same polarity together. At each end of battery stack 10, a set of conduits 32 is connected to the tab portion of the end cells. These conduits lead to an external battery terminal on each side of the battery stack for connection to a power supply for charging the battery or a load for discharging the battery.
Referring to Figure 3, a front elevation assembly view of electrode pair 12 is shown, and serves to illus-trate the method of joining bus-bar 20 to zinc electrode 1~) and to the graphite frame 26 of chlorine electrode structure 18. A plurality of holes of openings 34 are provided in tab portion 28 of zinc electrode 16, and similarly a plurality of openings 36 are provided in tab portion 29 of graphite frame 26. Openings 34 and 36 are generally aligned along the length of their respective tab portions 28 and 29, and t]le position of zinc electrode 16 and chlorine electrode structure 18 in battery stack 10 7~
is such that openings 34 are also aligned with openings 36. Bus-bar 20 has a sufficient length and width to completely cover one side of both openings 34 and 36 when placed in the position shown in Figure 2. A pair of support members 38 and 40 are also provided and sized to cover the opposite sides of these openings, with support member 38 for covering openings 34 and suppor~ memher 40 for covering openings 36. Accordingly, after drilling or otherwise providing for openings 34 in zinc electrode 16, tab portion 28 is interposed between bus-bar 20 and sup-port member 38 such that openings 34 are completely covered.
Similarly, tab portion 29 of chlorine elec~rode structure 18 is interposed between bus-bar 20 and support member 40 such that openings 36 are completely covered. Bus-bar 1~ 20 and support member 38 are ~hen resistance spot welded to ~inc electrode 16 a~ openings 34. Similarly, bus-bar 20 and support member 40 are resistance spot welded to graphite frame 26 of chlorine electrode structure 18 at openings 36. Although six openings are provided in both zinc electrode 16 and chlorine electrode structure 18, this number is not critical and may be varied depending on the materials used and the size of the surfaces to be joined.
Referring to Figure 4, a schematic representation of an arrangement 42 for resistance spot welding is il-lustrated. A graphite member 44 is provided with a plurality of openings 46 and 48. Graphite member 44 is interposed between two metal members 50 and 52, and these metal members are positioned to cover openings 46 and 48.
A pair of opposing welding electrodes 54 a~d 56 are ..... ...... .. ~ .. . . . .. .
7~
provided to spot weld metal members 50 and 52 to graphite member 44 at opening 46. Welding electrode 54 is position~d on metal member 50 and welding electrcde 56 is positioned under metal membe~ 52 such that the welding electrodes are aligned with opening 46. Welding electrodes 54 and 56 are connected to a transformer 58 via electrical conduits r 60 and 62. Transformer 58 is adapted to produce a suf-ficiently high electrical current to resistance spot weld metal members 50 and 52 to graphite member 44. Before the electrical current is passed through welding electrodes 54 and 56, a predetermined amount of pressure is applied to metal members 50 and 52 by ~he welding electrodes.
During the resistance spot welding, a portion of the metal from metal members 50 and 52 flows into opening 46 under the pressure of welding electrodes 54 and 56. A column of metal is thereby formed in the opening, and the gap between metal members 50 and 52 is bridged. After the flow of electrical current ceases and as the column of metal formcd cools, it contracts and exerts a force drawin~
~0 metal members 50 and 52 together. Accordingly, the welding o~ metal members 50 and 52 together achieves a good electrical contact between the metal members and graphite member 44 by the compression of the metal members against the graphite member. Furthermore, some penetration of the metal from metal members 50 and 52 into the pores of graphite member 44 also occurs. The degree of this pene-tration is dependent upon the porosity of graphite member 44. This penetration also inhances the electrical con-tact between metal members S0 and 52 and graphite member 44. It will also be appreciated by those skilled in the art that the column of metal formed in opening 46 provides ... . . .
~ ~ ~57~
direct electrical contact between metal members 50 and 52. This becomes important when one of the metal members is acting as a current collecting bus-bar, such as bus-bar 20 of Figures 1-3. Thus, support members 38 and 40 will S in essence form a part of bus-bar 20 after welding, and thereby increase the contact surface area used to transfer current between the electrodes and the bus-bar. Again, the increased contact surface area will enhance the electrical connection and reduce the voltaic losses in battery stack 10.
It will also be appreciated by those skilled in the art that welding electrodes 54 and 56 may be used to resistance spot weld metal members 50 and 52 to graphite member 44 at opening 48. Alternatively, another set of welding electrodes may be provided so that the spot welding at openings 4~ and 48 may occur simultaneously.
Accordingly, each spot weld at openings 34 and 36 in electrode pair 12 may be accomplished consequentively with one set of welding electrodes or a plurality of welds may be accomplished simultaneously with a corresponding plurality of welding electrodes.
Example Dense graphite has been joined to two titanium metal bars in the following manner. A suitable number of openings were provided in an ATJ grade graphite plate. The two titanium bars were sandblasted with fine sand to clean the surface of any oxide layer or grease that may have been present. It should be noted that other surface pre-paration techniques well known in the art may also be employed. Both the graphite plate and t]-e titanium bars ,, .. _ .. .. f 5t7~
had a thickness of one millime~er, and the openings in ~he graphite plate had a diameter of two millimeters. After the titanium bars were positioned to cover the openings in the graphite plate, a pressure of lOOkg was applied to the titanium bars at the first opening selected for welding by a pair of opposing welding electrodes. A
short current pulse of two-three peTiods was passed through the welding electrodes to achieve the spot weld. The welding equipment used was a*ESAB SVPR 753, and the welding surface area of the welding electrodes was thirt~
millimeters squared. Even though titanium is extremely reactive in an oxygen and nitrogen atmosphere above 1000F9 it was found that no special atmospheric shielding ~such as argon or helium gas) was required for the re-sistance spot welding. Due to the gas impermeability of the materials used and the arrangement employed, only a small amount of air was available in the openings of the graphite plate. Although some oxida~ion may ~ossibly have occurred, it did not a~fect the integrity of the electrical contact achie~ed.
It will be appreciated by those skilled in the art that various changes and modifications may be made to the method and structure described in this specification without departing from the spirit and scope of the in-vention as defined by the appended claims. For example, the amount of pressure applied, the size of the openings, and time and amount of electrical current used, are de-pendent upon the selection and dimensions of the materials selected~ such as employing porous graphite instead of dense graphite. The ~arious embodiments which have been * - Trade Mark ~s -10' 357~
. .
set forth were for the purpose of illustration and were not intended to limit the invention.
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will come into contact. Although titanium is extremely reactive above 1000F in an oxygen and nitrogen atmosphere, it has been found that no special atmospheric shielding is required for the resistance spot welding.
Other features and advantages of the present invention will become apparent in view of the drawings and the following detailed description of the preferred embodiment.
BRIEF DESCRIP~ION OF THE DRAl~INGS
Figure l is a perspective view of a section of a zinc-chloride bat~ery stack constructed in accordance with the present invention.
Figure 2 is a perspective view of an electrode pair forming a portion of the battery stack of Figure l.
Figure 3 is a front elevation assembly view of the electrode pair of Figure 2.
Figure 4 is a schematic representation of an arrangemellt for resistance spot welding metal to graphite.
DETAILED DESCRIPTION OF THE PREFERRED E~BODIMENT
Referring to Figure 1, a perspective view of a section of a zinc-chloride battery stack 10 is shown.
Battery stack 10 is generally comprised of a plurality of electrode pairs 12, shown individually in Figure 2, and a plastic frame 14. Each electrode pair 12 ls comprised of a zinc electrode 16, a chlorine electrode structure 18, and a bus-bar 20 coupling the zinc electrode to the chlorine electrode structure. Chlorine electrode structure 18 includes a pair of chlorine electrode members 22 and ~5~
24 joined to a graphite frame 26. Zinc electrode 16 is pre-fexably constructed from a dense or fine yrained graphite, as exemplified by Union Carbide Corp. *ATJ or *EBP graphi-tes.
The zinc electrode also includes a tab portion 2~ projecting from the top of the electrode to provide a surface area for connection to bus-bar 20.
Chlorine electrode members 22 and 24 are preferably constructed from liquid-permeable but gas-impermeable porous graphite, as exemplified by Union Carbide Corp. *PG~60 or *Airco Speer 37-G graphite. Graphite frame 26 is also prefer-ably constructed from dense graphite, and serves to separate the t~o chlorine electrode members and acts as an electrical conduit. This graphite frame is comprised of top leg 26a and a side leg 26b at each end of the chlorine electrode structure.
The graphite frame also includes a tab portion 29 which is used to electrically connect chlorine electrode structure 18 to the bus-bar 20. A detailed description of the connection between electrode me~bers 22 and 24 and the graphite frame 26 is set forth in a co-filed Canadian Patent Application ~0 Serlal No. 389,122, filed October 30, 1981, entitled "A ~ethod Of Joining Graphite To Graphite", assigned to the assignee of the present inyention.
Plastic frame 14 is preferably constructed from thermoplastic resins which are chemically resistant to ~he zinc-chloride battery environment, as exemplified by General Tire & Rubber Corp, *Boltron polyvinyl chloride (4008-2124), Dupont *Teflon (tetrafluori~naded ethylene), and Pennwalt *Kynar (polyvinylidene fluoride). Plastic frame 14 serves -to align and separate electrode pairs 12, *-Trade marks~
mab/,4,4~, . . .
and provides a means to convey the electrolyte to chlorine electrode structure 18. The chlorine electrode structure is open at the bottom between electrode members 22 and 24 to receive electrolyte, as graphite frame 26 does not in-clude a bottom leg.
Bus-bar 20 preferably constructed from titanium r or tantalum due to their mechanical strength, electrical conductivity, and resistance to chemical corrosion in the zinc-chloride battery environment. This bus-bar serves as a curren~ collector and connects adjacent cells of battery stac~ 10 electrically in series. Current sharing is facilitated between the cells arranged in parallel by a clip-on titanium s~rip 30, which is used to connect bus-bars of the same polarity together. At each end of battery stack 10, a set of conduits 32 is connected to the tab portion of the end cells. These conduits lead to an external battery terminal on each side of the battery stack for connection to a power supply for charging the battery or a load for discharging the battery.
Referring to Figure 3, a front elevation assembly view of electrode pair 12 is shown, and serves to illus-trate the method of joining bus-bar 20 to zinc electrode 1~) and to the graphite frame 26 of chlorine electrode structure 18. A plurality of holes of openings 34 are provided in tab portion 28 of zinc electrode 16, and similarly a plurality of openings 36 are provided in tab portion 29 of graphite frame 26. Openings 34 and 36 are generally aligned along the length of their respective tab portions 28 and 29, and t]le position of zinc electrode 16 and chlorine electrode structure 18 in battery stack 10 7~
is such that openings 34 are also aligned with openings 36. Bus-bar 20 has a sufficient length and width to completely cover one side of both openings 34 and 36 when placed in the position shown in Figure 2. A pair of support members 38 and 40 are also provided and sized to cover the opposite sides of these openings, with support member 38 for covering openings 34 and suppor~ memher 40 for covering openings 36. Accordingly, after drilling or otherwise providing for openings 34 in zinc electrode 16, tab portion 28 is interposed between bus-bar 20 and sup-port member 38 such that openings 34 are completely covered.
Similarly, tab portion 29 of chlorine elec~rode structure 18 is interposed between bus-bar 20 and support member 40 such that openings 36 are completely covered. Bus-bar 1~ 20 and support member 38 are ~hen resistance spot welded to ~inc electrode 16 a~ openings 34. Similarly, bus-bar 20 and support member 40 are resistance spot welded to graphite frame 26 of chlorine electrode structure 18 at openings 36. Although six openings are provided in both zinc electrode 16 and chlorine electrode structure 18, this number is not critical and may be varied depending on the materials used and the size of the surfaces to be joined.
Referring to Figure 4, a schematic representation of an arrangement 42 for resistance spot welding is il-lustrated. A graphite member 44 is provided with a plurality of openings 46 and 48. Graphite member 44 is interposed between two metal members 50 and 52, and these metal members are positioned to cover openings 46 and 48.
A pair of opposing welding electrodes 54 a~d 56 are ..... ...... .. ~ .. . . . .. .
7~
provided to spot weld metal members 50 and 52 to graphite member 44 at opening 46. Welding electrode 54 is position~d on metal member 50 and welding electrcde 56 is positioned under metal membe~ 52 such that the welding electrodes are aligned with opening 46. Welding electrodes 54 and 56 are connected to a transformer 58 via electrical conduits r 60 and 62. Transformer 58 is adapted to produce a suf-ficiently high electrical current to resistance spot weld metal members 50 and 52 to graphite member 44. Before the electrical current is passed through welding electrodes 54 and 56, a predetermined amount of pressure is applied to metal members 50 and 52 by ~he welding electrodes.
During the resistance spot welding, a portion of the metal from metal members 50 and 52 flows into opening 46 under the pressure of welding electrodes 54 and 56. A column of metal is thereby formed in the opening, and the gap between metal members 50 and 52 is bridged. After the flow of electrical current ceases and as the column of metal formcd cools, it contracts and exerts a force drawin~
~0 metal members 50 and 52 together. Accordingly, the welding o~ metal members 50 and 52 together achieves a good electrical contact between the metal members and graphite member 44 by the compression of the metal members against the graphite member. Furthermore, some penetration of the metal from metal members 50 and 52 into the pores of graphite member 44 also occurs. The degree of this pene-tration is dependent upon the porosity of graphite member 44. This penetration also inhances the electrical con-tact between metal members S0 and 52 and graphite member 44. It will also be appreciated by those skilled in the art that the column of metal formed in opening 46 provides ... . . .
~ ~ ~57~
direct electrical contact between metal members 50 and 52. This becomes important when one of the metal members is acting as a current collecting bus-bar, such as bus-bar 20 of Figures 1-3. Thus, support members 38 and 40 will S in essence form a part of bus-bar 20 after welding, and thereby increase the contact surface area used to transfer current between the electrodes and the bus-bar. Again, the increased contact surface area will enhance the electrical connection and reduce the voltaic losses in battery stack 10.
It will also be appreciated by those skilled in the art that welding electrodes 54 and 56 may be used to resistance spot weld metal members 50 and 52 to graphite member 44 at opening 48. Alternatively, another set of welding electrodes may be provided so that the spot welding at openings 4~ and 48 may occur simultaneously.
Accordingly, each spot weld at openings 34 and 36 in electrode pair 12 may be accomplished consequentively with one set of welding electrodes or a plurality of welds may be accomplished simultaneously with a corresponding plurality of welding electrodes.
Example Dense graphite has been joined to two titanium metal bars in the following manner. A suitable number of openings were provided in an ATJ grade graphite plate. The two titanium bars were sandblasted with fine sand to clean the surface of any oxide layer or grease that may have been present. It should be noted that other surface pre-paration techniques well known in the art may also be employed. Both the graphite plate and t]-e titanium bars ,, .. _ .. .. f 5t7~
had a thickness of one millime~er, and the openings in ~he graphite plate had a diameter of two millimeters. After the titanium bars were positioned to cover the openings in the graphite plate, a pressure of lOOkg was applied to the titanium bars at the first opening selected for welding by a pair of opposing welding electrodes. A
short current pulse of two-three peTiods was passed through the welding electrodes to achieve the spot weld. The welding equipment used was a*ESAB SVPR 753, and the welding surface area of the welding electrodes was thirt~
millimeters squared. Even though titanium is extremely reactive in an oxygen and nitrogen atmosphere above 1000F9 it was found that no special atmospheric shielding ~such as argon or helium gas) was required for the re-sistance spot welding. Due to the gas impermeability of the materials used and the arrangement employed, only a small amount of air was available in the openings of the graphite plate. Although some oxida~ion may ~ossibly have occurred, it did not a~fect the integrity of the electrical contact achie~ed.
It will be appreciated by those skilled in the art that various changes and modifications may be made to the method and structure described in this specification without departing from the spirit and scope of the in-vention as defined by the appended claims. For example, the amount of pressure applied, the size of the openings, and time and amount of electrical current used, are de-pendent upon the selection and dimensions of the materials selected~ such as employing porous graphite instead of dense graphite. The ~arious embodiments which have been * - Trade Mark ~s -10' 357~
. .
set forth were for the purpose of illustration and were not intended to limit the invention.
~, . .... . ,. ., -- ,
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of joining two metal members to a graphite member to form a structure having a low-transition resistance, comprising the steps of:
(a) providing a plurality of openings in said graphite member;
(b) interposing said graphite member between said metal members and positioning said metal members to cover said openings in said graphite member; and (c) resistance spot welding said metal members together at said openings in said graphite member to thereby join said metal members to said graphite member.
(a) providing a plurality of openings in said graphite member;
(b) interposing said graphite member between said metal members and positioning said metal members to cover said openings in said graphite member; and (c) resistance spot welding said metal members together at said openings in said graphite member to thereby join said metal members to said graphite member.
2. The method according to Claim 1, wherein said metal members are spot welded together through said openings in said graphite member.
3. The method according to Claim 2, wherein said metal members are constructed from titanium, and said graphite member is constructed from dense graphite.
4. The method according to Claim 3, further including the step of cleaning said titanium members to remove any oxide layer or grease from the surfaces thereof prior to the welding of said members.
5. The method according to Claim 4, wherein said titanium members are cleaned by sandblasting.
6. The method according to Claim 2, wherein said metal members are constructed from tantalum, and said graphite member is constructed from dense graphite.
7. A method of joining metal to graphite, comprising the steps of:
(a) providing a plurality of openings in a graphite member to be joined;
(b) interposing said graphite member between two metal members and positioning said metal members to cover said openings in said graphite member; and (c) resistance spot welding said metal members together through said openings in said graphite member.
(a) providing a plurality of openings in a graphite member to be joined;
(b) interposing said graphite member between two metal members and positioning said metal members to cover said openings in said graphite member; and (c) resistance spot welding said metal members together through said openings in said graphite member.
8. The method according to Claim 2, wherein said spot welding at each of said openings in said graphite member occurs simultaneously.
9. The method according to Claim 7, wherein said spot welding at each of said openings in said graphite member occurs successively.
10. The method according to Claim 8, wherein a pair of opposing welding electrodes is provided for said spot welding.
11. The method according to Claim 9, wherein said metal members are compressed together by a predetermined amount of pressure applied to said metal members during said spot welding.
12. A method of joining metal to graphite, comprising the steps of:
(a) providing a plurality of openings in a graphite member to be joined;
(b) interposing said graphite member between two metal members and positioning said metal members to cover said openings in said graphite member;
(c) applying a predetermined amount of force to said metal members with a pair of opposing welding electrodes aligned with one of said openings in said graphite member.
(d) passing sufficient electrical current through said welding electrodes to spot weld said metal members together through said openings; and (e) repeating steps (c) and (d) until said metal members have been spot welded together at each of said openings in said graphite member.
(a) providing a plurality of openings in a graphite member to be joined;
(b) interposing said graphite member between two metal members and positioning said metal members to cover said openings in said graphite member;
(c) applying a predetermined amount of force to said metal members with a pair of opposing welding electrodes aligned with one of said openings in said graphite member.
(d) passing sufficient electrical current through said welding electrodes to spot weld said metal members together through said openings; and (e) repeating steps (c) and (d) until said metal members have been spot welded together at each of said openings in said graphite member.
13. The method according to Claim 12, wherein said graphite member is a dense graphite plate, and said openings therein are spaced in alignment.
14. The method according to Claim 13, wherein each of said metal members is a titanium bar having a width greater than the diameter of said openings in said dense graphite plate but substantially less than the width of said graphite plate.
15. The method according to Claim 14, wherein said openings in said dense graphite plate are provided in a tab portion of said dense graphite plate.
16. A method of forming a bus-bar electrical connection between a pair of opposite polarity graphite electrodes positioned generally end-to-end in an electro-chemical cell stack, comprising the steps of:
(a) providing a plurality of aligned openings in both of said graphite electrodes;
(b) providing a metal bus-bar member having a size sufficient to extend between and cover a first side of said openings for both of said graphite electrodes, and providing a pair of metal support members each having a size sufficient to cover a second opposing side of said openings for one of said graphite electrodes;
(c) positioning said metal bus-bar member to extend between and cover said first side of said openings for both of said graphite electrodes, positioning one of said metal support members to cover said second opposing size of said openings for one of said graphite electrodes, and positioning the other of said metal support members to cover said second opposing side of said openings for the other of said graphite electrodes; and (d) resistance spot welding said metal bus-bar member to said pair of metal support members and to thereby afix said bus-bar members and said support members to said pair of graphite electrodes at each of said openings in said graphite members.
(a) providing a plurality of aligned openings in both of said graphite electrodes;
(b) providing a metal bus-bar member having a size sufficient to extend between and cover a first side of said openings for both of said graphite electrodes, and providing a pair of metal support members each having a size sufficient to cover a second opposing side of said openings for one of said graphite electrodes;
(c) positioning said metal bus-bar member to extend between and cover said first side of said openings for both of said graphite electrodes, positioning one of said metal support members to cover said second opposing size of said openings for one of said graphite electrodes, and positioning the other of said metal support members to cover said second opposing side of said openings for the other of said graphite electrodes; and (d) resistance spot welding said metal bus-bar member to said pair of metal support members and to thereby afix said bus-bar members and said support members to said pair of graphite electrodes at each of said openings in said graphite members.
17. The method according to Claim 16, wherein said openings are provided in a tab portion of said graphite electrodes.
18. The method according to Claim 17, wherein said tab portions are disposed above an active surface area of said graphite electrodes.
19. The method according to Claim 16, wherein said metal bus-bar member and said metal support members are constructed from titanium.
20. The method according to Claim 19, wherein one of said graphite electrodes is a zinc electrode, and the other of said graphite electrodes is a chlorine electrode structure.
21. The method according to Claim 20, wherein said zinc electrode and at least said tab portion of said chlorine electrode structure are constructed from dense graphite.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US246,841 | 1981-03-23 | ||
| US06/246,841 US4343982A (en) | 1981-03-23 | 1981-03-23 | Method of joining metal to graphite by spot welding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1185774A true CA1185774A (en) | 1985-04-23 |
Family
ID=22932454
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389142A Expired CA1185774A (en) | 1981-03-23 | 1981-10-30 | Method for joining metal to graphite |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4343982A (en) |
| JP (1) | JPS57156878A (en) |
| BE (1) | BE891802A (en) |
| CA (1) | CA1185774A (en) |
| DE (1) | DE3147191A1 (en) |
| FR (1) | FR2502141B1 (en) |
| GB (1) | GB2095151B (en) |
| IT (1) | IT1139588B (en) |
| SE (1) | SE8107401L (en) |
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|---|---|---|---|---|
| DE3303244A1 (en) * | 1982-10-07 | 1984-04-12 | Schäfer Werke GmbH, 5908 Neunkirchen | METHOD FOR CONNECTING TWO PARTS THAT ARE NOT DIRECTLY WELDABLE |
| US5382769A (en) * | 1990-04-03 | 1995-01-17 | Lockheed Corporation | Resistance brazed joints for carbon/carbon structures |
| US7126096B1 (en) | 1991-04-05 | 2006-10-24 | Th Boeing Company | Resistance welding of thermoplastics in aerospace structure |
| US5624594A (en) * | 1991-04-05 | 1997-04-29 | The Boeing Company | Fixed coil induction heater for thermoplastic welding |
| US5641422A (en) * | 1991-04-05 | 1997-06-24 | The Boeing Company | Thermoplastic welding of organic resin composites using a fixed coil induction heater |
| US5410132A (en) * | 1991-10-15 | 1995-04-25 | The Boeing Company | Superplastic forming using induction heating |
| US5723849A (en) * | 1991-04-05 | 1998-03-03 | The Boeing Company | Reinforced susceptor for induction or resistance welding of thermoplastic composites |
| US5808281A (en) * | 1991-04-05 | 1998-09-15 | The Boeing Company | Multilayer susceptors for achieving thermal uniformity in induction processing of organic matrix composites or metals |
| US5793024A (en) * | 1991-04-05 | 1998-08-11 | The Boeing Company | Bonding using induction heating |
| US5728309A (en) * | 1991-04-05 | 1998-03-17 | The Boeing Company | Method for achieving thermal uniformity in induction processing of organic matrix composites or metals |
| US5645744A (en) * | 1991-04-05 | 1997-07-08 | The Boeing Company | Retort for achieving thermal uniformity in induction processing of organic matrix composites or metals |
| US5508496A (en) * | 1991-10-18 | 1996-04-16 | The Boeing Company | Selvaged susceptor for thermoplastic welding by induction heating |
| US5444220A (en) * | 1991-10-18 | 1995-08-22 | The Boeing Company | Asymmetric induction work coil for thermoplastic welding |
| US5500511A (en) * | 1991-10-18 | 1996-03-19 | The Boeing Company | Tailored susceptors for induction welding of thermoplastic |
| US5710412A (en) * | 1994-09-28 | 1998-01-20 | The Boeing Company | Fluid tooling for thermoplastic welding |
| US5660669A (en) * | 1994-12-09 | 1997-08-26 | The Boeing Company | Thermoplastic welding |
| US5486684A (en) * | 1995-01-03 | 1996-01-23 | The Boeing Company | Multipass induction heating for thermoplastic welding |
| US5573613A (en) * | 1995-01-03 | 1996-11-12 | Lunden; C. David | Induction thermometry |
| US6602810B1 (en) | 1995-06-06 | 2003-08-05 | The Boeing Company | Method for alleviating residual tensile strain in thermoplastic welds |
| US5705795A (en) * | 1995-06-06 | 1998-01-06 | The Boeing Company | Gap filling for thermoplastic welds |
| US5717191A (en) * | 1995-06-06 | 1998-02-10 | The Boeing Company | Structural susceptor for thermoplastic welding |
| US5829716A (en) * | 1995-06-07 | 1998-11-03 | The Boeing Company | Welded aerospace structure using a hybrid metal webbed composite beam |
| US5556565A (en) * | 1995-06-07 | 1996-09-17 | The Boeing Company | Method for composite welding using a hybrid metal webbed composite beam |
| US5756973A (en) * | 1995-06-07 | 1998-05-26 | The Boeing Company | Barbed susceptor for improviing pulloff strength in welded thermoplastic composite structures |
| US5760379A (en) * | 1995-10-26 | 1998-06-02 | The Boeing Company | Monitoring the bond line temperature in thermoplastic welds |
| US5916469A (en) * | 1996-06-06 | 1999-06-29 | The Boeing Company | Susceptor integration into reinforced thermoplastic composites |
| US5869814A (en) * | 1996-07-29 | 1999-02-09 | The Boeing Company | Post-weld annealing of thermoplastic welds |
| US5902935A (en) * | 1996-09-03 | 1999-05-11 | Georgeson; Gary E. | Nondestructive evaluation of composite bonds, especially thermoplastic induction welds |
| US6284089B1 (en) | 1997-12-23 | 2001-09-04 | The Boeing Company | Thermoplastic seam welds |
| JPH11283608A (en) | 1998-03-26 | 1999-10-15 | Tdk Corp | Electrode for battery, manufacture thereof and battery |
| EP1183746A1 (en) * | 2000-01-26 | 2002-03-06 | Lion Compact Energy, Inc. | Electrolytes for dual graphite energy storage system |
| CN1240148C (en) * | 2000-11-01 | 2006-02-01 | 索尼株式会社 | Cell, cell production method, welded article production method and pedestal |
| JP4852784B2 (en) * | 2000-11-01 | 2012-01-11 | ソニー株式会社 | Battery and manufacturing method thereof |
| JP5344423B2 (en) | 2008-09-26 | 2013-11-20 | 株式会社Ｓｕｍｃｏ | Method for producing carbon electrode and method for producing quartz glass crucible |
| TWI376831B (en) * | 2009-03-17 | 2012-11-11 | Energy Control Ltd | High conductivity battery connecting structure by using graphite |
| CN101847702B (en) * | 2009-03-24 | 2013-02-27 | 电能有限公司 | Structure for high-conductivity connection outside batteries by using graphite |
| GB2469449B (en) * | 2009-04-14 | 2014-06-04 | Energy Control Ltd | Connecting structure for exteriorly connecting battery cells |
| DE102009035498A1 (en) | 2009-07-31 | 2011-02-03 | Daimler Ag | Single cell for lithium ion battery of vehicle, has electrode stack whose poles are arranged between housing side walls and metallic pressing plate and welded in sections with housing side walls and pressing plate |
| US8361647B2 (en) | 2010-03-19 | 2013-01-29 | GM Global Technology Operations LLC | Reversible battery assembly and tooling for automated high volume production |
| US10058949B2 (en) * | 2013-10-04 | 2018-08-28 | GM Global Technology Operations LLC | Resistance spot welding steel and aluminum workpieces using insertable cover |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB482046A (en) * | 1900-01-01 | |||
| GB504405A (en) * | 1937-11-03 | 1939-04-25 | Frederick John Weakley | Improvements relating to welded construction |
| FR930961A (en) * | 1942-04-21 | 1948-02-10 | Assembly process by spot welding, in particular for mixed light alloy-steel constructions | |
| US2356049A (en) * | 1942-06-19 | 1944-08-15 | Westinghouse Electric & Mfg Co | Method of resistance welding |
| FR1208618A (en) * | 1958-09-02 | 1960-02-24 | Electrochimie Soc | Improvement in current leads to graphite electrodes |
| US3300854A (en) * | 1964-05-14 | 1967-01-31 | Mcdonnell Aircraft | Method of making refractory metal structures with an oxidation resistant coating |
| GB1302550A (en) * | 1969-08-22 | 1973-01-10 | ||
| JPS492665A (en) * | 1972-04-26 | 1974-01-10 | ||
| US3878356A (en) * | 1973-09-27 | 1975-04-15 | Cleveland E Roye | Diffusion band riveting method |
| JPS50137324U (en) * | 1974-04-30 | 1975-11-12 | ||
| US4071660A (en) * | 1976-04-26 | 1978-01-31 | Energy Development Associates | Electrode for a zinc-chloride battery and batteries containing the same |
| US4100332A (en) * | 1977-02-22 | 1978-07-11 | Energy Development Associates | Comb type bipolar electrode elements and battery stacks thereof |
| US4166210A (en) * | 1977-04-26 | 1979-08-28 | General Battery Corporation | Electrodes for use in the extrusion-fusion welding of lead parts through an aperture in a battery case |
-
1981
- 1981-03-23 US US06/246,841 patent/US4343982A/en not_active Expired - Lifetime
- 1981-10-30 FR FR8120465A patent/FR2502141B1/en not_active Expired
- 1981-10-30 CA CA000389142A patent/CA1185774A/en not_active Expired
- 1981-11-03 GB GB8133113A patent/GB2095151B/en not_active Expired
- 1981-11-12 IT IT25018/81A patent/IT1139588B/en active
- 1981-11-27 DE DE19813147191 patent/DE3147191A1/en active Granted
- 1981-12-02 JP JP56194356A patent/JPS57156878A/en active Granted
- 1981-12-10 SE SE8107401A patent/SE8107401L/en not_active Application Discontinuation
-
1982
- 1982-01-15 BE BE0/207074A patent/BE891802A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| US4343982A (en) | 1982-08-10 |
| IT8125018A0 (en) | 1981-11-12 |
| FR2502141B1 (en) | 1986-09-12 |
| JPH0237266B2 (en) | 1990-08-23 |
| BE891802A (en) | 1982-04-30 |
| FR2502141A1 (en) | 1982-09-24 |
| GB2095151A (en) | 1982-09-29 |
| JPS57156878A (en) | 1982-09-28 |
| SE8107401L (en) | 1982-09-24 |
| IT1139588B (en) | 1986-09-24 |
| GB2095151B (en) | 1985-08-21 |
| DE3147191C2 (en) | 1992-04-30 |
| DE3147191A1 (en) | 1982-09-30 |
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