MXPA00001370A - Reinforced coiled electrode assemblies and methods of producing same - Google Patents

Abstract

The present invention relates to coiled electrode assemblies having conductive tabs, methods of attaching the conductive tabs to the coiled electrode, and electrochemical cells employing such assemblies. An electrode plate which is coated with active material has a designated area for tab attachment. The conductive tab area's active material is pierced with opposing, offset piercing plates which have raised surface probes which penetrate the conductive tab area's coating and substrate. This tab area is cleared of active material and reinforced with a reinforcing material and a conductive tab is welded to the thus treated area resulting in an electrode plate having a strong integrated tab assembly.

Description

ASSEMBLIES OF ARROPELLED ELECTRODES, REINFORCED AND METHODS TO PRODUCE THEMSELVES FIELD OF THE INVENTION This invention relates to spiral electrode assemblies having conductive tabs, methods for joining the tabs conductive to the spiral electrode, and electrochemical cells employing such assemblies or assemblies.

BACKGROUND OF THE INVENTION Electrochemical cells employing spiral electrode assemblies are widely known in the art. In many of these cellular structures the spiral electrode assembly is inserted into a composite housing or housing which serves as the current conductive terminals for the. cell. When this type of cell is assembled, a tongue which is conductive to the electrodes can be secured first by appropriate means, such as welding.

REF. : 32724 Cells employing spiral electrode assemblies can be produced using various electrochemical systems, such as nickel metal hydrides, nickel cadmium, zinc nickel and the like. When the nickel metal hydride cells are used, the negative electrode of the nickel metal hydride cells is typically a hydrogen storage electrode in the form of a metal hydride. The positive electrode is typically nickel hydroxide. These cells also contain a separator and an electrolyte, as is known in the art. The positive electrode strip is generally the last electrode wound by the nickel metal hydride cells and has a conductive tab secured to a selected area of the carrier at one end and the cellular housing or housing at the opposite end. Prior to securing the electrode conductive tab, a selected area of the conductive carrier may be free of any active electrode material. Conventionally, this removal is by a process such as air jets, scrapes, suction, purification or ultrasonic cleaning and the like. However, the use of these methods is dependent on the carrier (substrate) for the removal efficiency of the active material from the substrate and the firmness of the bonding connection resulting from the conductive tab to the substrate. With the development of conductive carriers made of felt, foam and other fragile substrates, waste or debris from the active material removed from the substrate and attached to a conductive tongue has become more difficult. Various methods have been used to break or release the active material from the substrate, such as the ultrasonic removal of the active material from the desired area, the removal of the active material from the substrate along a complete edge of the electrode, the binding of the conductive tongues in the form of a wt "or wv" or "h" to strengthen the area of the tongue, and others. Although the removal of the active material from the full length of the electrode contributes to the development of the efficiency of these cell types, the tendency today is to maximize the capacity through the much greater reaction of the active material present in the electrochemical cell as possible. There is still a need for methods for the fabrication of spiral electrode assemblies, which remove substantially only a small section of the active material from the brittle substrates without the weakening or damage of the substrates, and which allows the joining of a Conductive tongue to the substrates thus cleaned or purified.

DESCRIPTION OF THE INVENTION The invention relates to electrode plates used in spiral electrode assemblies, which have a conductive tongue attached thereto. By treating the area of the conductive tongue with an electrode plate coated with the active material in the manner described herein, the subsequent steps of the ultrasonic scavenging remove substantially all of the active material present in such an area. Significantly, the purified or cleaned area is reinforced with a reinforcement material. The welding or ultrasonic bonding of a tongue conductive to the area thus treated results in an electrode plate having a strong integrated tongue assembly. The first step of the invention is a drilling step, wherein the opposing strips of a branch or elbow are pressed against the electrode plate in the area of the conductive tongue. The perforation plates have probes of elevated surfaces, which penetrate the active material and form a model of pins in the treated area. The next step of cleaning or purifying the treated area results in a conductive tongue area substantially free of the active material. After the cleaning or purifying stage, the area is reinforced with a reinforcement material by folding and compressing the material in the cleaned area. Several types of conductive tabs can then be attached to the cleaned area, resulting in a strong integrated tongue assembly. It has also been found that the electrodes prepared by the process of the present invention are easier to assemble as the spiral assemblies for use in electrochemical cells, due to a relatively flat tongue area. In addition, the process allows the incorporation of more active material in the finished electrochemical cells, resulting in a higher capacity. Reinforcement can strengthen the bond and can lead to a longer product life time. Figure 1 is a side view of an electrode plate in contact with perforation plates having raised surface probes. Figure 2 is a front view of a perforation plate having probes of elevated surfaces. Figure 2a is an enlarged side view of a raised surface probe of a perforation plate. Figure 3 is a schematic diagram showing a strong bonding or welding process. Figure 4 is a schematic diagram showing an ultrasonic bonding or welding process. In the first step of the process of the present invention, the conductive tongue area of an electrode plate is perforated with opposing branch or elbow perforation plates having raised surface probes. In the next step, the resulting area is cleaned of the active material to expose a porous, implicit substrate, substantially free of the active material. The cleaned area is reinforced with a reinforcing material.

A conductive tongue is then attached to the porous substrate, implicit, exposed. The substrates employed in the preparation of the positive electrodes in the electrochemical cells made in accordance with this invention include any highly porous substrate having low mechanical firmness such as foam, felt and the like. The substrates are coated with an active material for the desired electrochemical system. In the case of nickel metal hydride cells, the active material of the positive electrode comprises one or a mixture of the nickel compounds, such as nickel hydroxide. The active material may also include other compounds, such as those known in the art, which include a conductivity enhancer such as cobalt oxide, a conductive material such as black carbon, a thick agent, a binder, and the like . The metal powders and other components are mixed with the water to form a wet suspension, which can be coated on the porous substrate by any of the known methods such as by doctor blades, roller coatings, spray covers and the like. The coated substrate can then be dried, and subjected to a scheduling process to form a hardened, soft electrode plate, using means known in the art. The final thickness of the electrode plates normally varies from about 0.6 to 0.7 mm, preferably from 0.63 to 0.61 mm. The electrode plates are then cut to the desired size for use in an electrochemical cell. It has been found that by piercing the conductive tongue area with the opposite branch or elbow perforation plates, the area of the conductive tongue can be substantially cleaned of the active material without damaging the implicit porous fragile substrate. The area of the conductive tongue to be cleaned or cleaned of the active material may be slightly larger than the width of the conductive tongue to be attached to the cleaned area. The drilling step is described in more detail in U.S. Patent No. 08 / 649,890, filed May 4, 1996, which is assigned to the same attorney of the present application and is thereby incorporated by reference. Figure 1 shows a front view of an electrode plate 1 in contact with the opposing piercing plates 2 in the piercing step. The electrode plate 1 is subjected to a pressure of about 20 to 110 psi from the opposite piercing plates 2 having probes of elevated surfaces in branches or bends 3 ending at a point. The raised surface probes are branches or elbows in such a way that when the opposite perforation plates contact the electrode plate, the points of the raised surface probes 3, penetrate the surface of the implicit porous substrate without contacting the others. In a more preferred embodiment, the probes of high surfaces penetrate the electrode plate through the implicit substrate, the pin does not leave the opposite surface of the electrode plate. Figure 2 shows a front view of a perforation plate 2 having probes of elevated surfaces of branches or elbows 3. The surface probes are branches or elbows of the adjacent probes by distance 4, and from the next row of probes of surface by the distance 5, in such a way that the probe of opposite surfaces avoids the contact of each of the others when it is pressed against the electrode plate. As shown in Figure 2a, an enlarged side view of a surface probe, the surface probes are preferably in angled shapes 6, being less than 6 degrees, preferably 18 to 22 degrees from a line drawn perpendicular to the base from the probe of the surface to the point of the surface probe. The surface probes have a base 7 of approximately 0.4 mm and are approximately 0.6 mm in height 8, depending on the thickness of the electrode plate. The base and height of the surface probes can be varied from these dimensions to prevent damage to the implicit porous substrate. If wider surface probes are used, the penetration depth of the surface probes on the electrode plates should be such that. the implicit porous substrate, is not damaged. The conductive tongue area of the electrode plate that has been treated with the piercing steps described above has a pin, diamond pattern on the surface of the electrode plate. Depending on the type of substrate and the thickness or thickness of the applied active material, one or more than one perforation step may be used to facilitate the substantial removal of the active material from this area during the next cleaning step. In the next stage of the process, the area of the conductive tongue is cleaned of the active material, using conventional means. In a preferred embodiment, the ultrasonic treatment is used to remove the active material. It is believed that the drilling step of the present invention also decreases the amount of ultrasonics necessary to substantially remove the active material from the treated area, resulting in less damage to the implicit fragile substrate. The type of equipment used for the application of ultrasonic to the various treated areas and typically including an ultrasonic tip or tip, have either raised or soft surfaces and an anvil having either raised or smooth surfaces. In a more preferred embodiment of the present invention, the ultrasonic tip or tip has a smooth surface and the anvil consists of a movable wheel with raised surfaces having obtuse points in diamond shapes, to prevent damage to the substrate. The amount of ultrasonics applied is typically in the range of the least about 20 kHz to 100 percent amplitude (approximately 20 kilojoules of energy) for a duration of about 0.5 to 1.0 seconds. A conductive tongue area treated with the piercing step and followed by an ultrasonic cleaning step has a borderline porous substrate substantially free of the active material in the area of the conductive tongue. The integrity of the fragile substrate remains intact. As a comparison, when the area of the conductive tongue is cleaned using only the ultrasonic cleaning without the piercing step, damage to the fibers of the fragile, implicit porous substrate can be observed. Ultrasonic cleaning of the conductive tongue without the use of at least one piercing stage, destroys the ability to bond or weld a tongue conductive to the area of the cleaned conductive tongue of the substrate. The clean electrode plate is reinforced with a reinforcing material, such as a filling material similar to a conductive foam or felt. For example, the conductive foam may be a nickel foam (eg 340, 400 or 500 bases by weight of the material) available from Katayama, Japan or Retec Porous Metals, Tuscumbia, Alabama. Generally, the reinforcing material is released in a cutting operation where the material is placed on a foldable and trimmed nail to a specified length. A small section of the reinforcing material is cut generally having an area that is approximately equal to the cleaned area. The reinforcing material can then be formed into a "V" shape by forcing a plunger or piston against the material and into a nail assembly. The reinforcing material is then placed on a cleaned area of the electrode plate and compressed to be blasted with the surface of the electrode plate. The reinforcement materials of a fold or double fold can be used. After the reinforcement material has been compressed in the cleaned area of the electrode plate, the reinforcing material can be secured in place with a joint, such as a bond or resistance weld or an ultrasonic joint or weld. The joints can make the tongue join stronger and can improve continuity between the filler material and the electrode plate. After removal of the active material from the treated area and reinforcement of the area, a conductive tongue can be attached to the substrate, using bonds or ultrasonic welds or resistances. The conductive tongue may be of nickel or nickel-coated steel, and may be of any desired shape such as a double-layer tongue (v-shaped or h-shaped) or a single-layer, smooth, rectangular tongue. In a preferred embodiment of the present invention, a rectangular single layer tab is attached to the substrate, using ultrasonic bonding or welding. The ultrasonic junction is encompassed using means known in the art. In a preferred embodiment, the ultrasonic furnace has raised surfaces and the anvil has a smooth surface. To form a friction joint or weld between the substrate and the conductive tongue, ultrasonic vibrations are applied at 20 KHz and 100 percent amplitude, in a parallel direction (180 degrees) to the surfaces to be joined or welded, with a pressure of union or welding of approximately 30 psi. Depending on the type of conductive tongue to be used, the bonding or welding energy can vary from about 18 joules per one tab of a single layer, up to about 30 to 45 joules per one tab of double layer, with a bonding time of about 0.5 to 1 second. In a more preferred embodiment of the present invention, a single-layer conductive tab is attached to the clean brittle substrate, using an ultrasonic tip or tip having a raised surface and an anvil having a smooth surface. It is inexplicable that a single layer conductive tongue and a brittle substrate can form a sufficient friction joint or weld, using a smooth anvil. Typically, the ultrasonic bonding or welding of a tongue conductive to a brittle substrate involves the use of a double-layer conductive tongue, such as a tongue h or a tongue v. These types of double-layer tongues facilitate the use of both, an anvil having high surfaces and an ultrasonic furnace having raised surfaces since the substrate is intermediate between two layers of metal and is not in contact with either the ultrasonic furnace or the anvil. The use of an anvil having high surfaces could destroy exposed fragile fibers of the substrate when it is attached to a single-layer conductive tongue. It has been found that by the use of the methods of the present invention, all the forms of the tabs can be joined or successfully welded to the conductive tongue area of a porous, brittle substrate, which uses a smooth anvil. The positive electrode having a connected conductive tab as described above, can then be processed using the conventional steps. These steps may include providing a pin on the tongue, above the edge of the electrode to improve flexibility and facilitate the joining of the tongue to the cell layer; and / or hitting the conductive tongue and the area of the conductive tongue to ensure the additional firmness of the joint and prevent internal shorts. The ability to use a single-layer conductive tongue opposite a double-layer conductive tongue provides improvements in commercial manufacturing processes by eliminating the raised area, which is normally associated with spiral electrode assemblies having a double layer tongue (ie double thickness). The removal of this raised area also reduces the possibility of internal shorts, and allows the use of additional layers of electrodes incorporated in the spiral electrode assemblies. The following examples compare the results of ultrasonic bonding or conventional strength bonds or solders using methods of the present invention. The positive electrodes are prepared by wet suspension of the desired ingredients (nickel hydroxide, cobalt oxide, gelling agents, binders and black carbon) on the nickel-coated foam substrates, which weigh between about 320 m2 / g to about 500 m2 / g, such as Eltec 400 foam from Eltec, Inc. The coated substrate is then dried at about 110 to 120 degrees Celsius and scheduled using pressures between about 30 to 40 tons, to form the positive electrode plates. The positive electrode plates are then cut to the desired size. A series of electrode plates are prepared using one or more perforation stages of the present invention, to form a treated conductive tongue area. The conductive tongue area is then cleaned or debugged using ultrasonic cleaning with an ultrasonic tip or end having a smooth surface and a movable wheel anvil having raised surfaces. A single-layer conductive tongue is then attached to the cleaned area, using solder or ultrasonic bonding. The ultrasonic bonding or welding is performed using an ultrasonic tip or tip having raised surfaces and an anvil having a smooth surface. Using conventional resistance welding or bonding, a double layer conductive tab is attached to a second series of electrode plates as described above. The firmness of the attached tabs is measured using a standard extraction test in Lloyd Instrumets, Model LRX, Pulltester. The test is run by screwing one end of the tester assembly to the conductive tab, and the other end of the bottom of the electrode plate. The screws are then removed in opposite directions at a speed of 5 mm per minute, until the connection between the tab and the electrode plate reaches the maximum force just before the weakening of the conductive tab / bond of the substrate. The results are reported in Table 1. A comparative example is run using an electrode plate which has been ultrasonically cleaned without using a piercing step of the present invention. A single-layer conductive tongue can not be welded or joined to this electrode plate using ultrasonic bonding or welding due to damage to the implied substrate and incomplete cleaning of the active material from the area of the conductive tongue. The results are shown below in Table 1. Each of the identification samples represents an average result for five samples from five different batches, using identical process steps.

Table 1 Extraction test Sample Bonding or solder Bonding or ultrasonic bond strength for tape (kg) (kg) A 0.7 0.71 B 0.71 0.66 C 0.77 0.62 D 0.7 0.84 Comparative Bonding was not possible The results show the firm bond strength when joins a single-layer conductive tongue, using the process of the present invention. In addition, the process of the present invention provides single-layer tabs / bonds of firm substrates comparable to those using double-layer tabs / substrates. The conductive tongue can be joined by resistance bonding. In a first stage in this process, the electrode penetrates to loosen the cover before cleaning. Partly due to the relatively high density of the scheduled electrode material, the subsequent process steps are most effective when the surface of the electrode plate has been fractured. With reference to Figure 3, the electrode plate is presented to the pre-treatment station 10, perpendicular to the fracture tips for the piercing step. One fracture tip is located at the top of the electrode surface, the other is below, The fracture tips are a set of opposing "jaws" that pierce the surface of the electrode to a particular depth and fracture the material without causing excessive damage to the substrate. The pre-treated electrode plate is present in an ultrasonic cleaning station 20. The pre-treated plate is positioned perpendicular to a combination of ultrasonic tip or anvil and anvil. The slot between the up or tip and the anvil is predetermined to fix the dimensions of the electrode plate. The pre-treated plate is introduced into the cleaning station. A small area (eg 6 mm by 7 mm) is cleaned by moving the combinations up to or tip / anvil through the area of the electrode plate to be cleaned, parallel to the electrode and at a specified depth. Cleaning is covered by ultrasonic vibration for a period of time. The clean or purged electrode plate is reinforced in the reinforcement station 30. A reinforcement material is applied in a three-stage process. First, the reinforcement material is placed on foldable and cut-out nails to a specified length. The reinforcing material is then formed in a "V" shape by the force of a plunger or piston, against the material and in a nail assembly. The reinforcing material is then placed on the clean area of the electrode plate and compressed to be blasted with the surface of the electrode plate. After the reinforcing material has been compressed in the clean area of the electrode plate, the reinforcing material is secured in place with a joint or weld in a securing station 40. The joint can make the tongue, join tightly and can improve the continuity between the filling material and the electrode plate. The securing joint can be a resistance joint or an ultrasonic joint. After the reinforcement, a conductive tongue is attached to the electrode plate at a resistance joining station 50. The electrode plate is present at the joining station, perpendicular to the joining tips. A short piece of the conductive stack tongue (eg 4mm by 18mm) is fed in position over the clean or purged reinforcement area of the electrode plate. The tongue material is placed on the reinforcement area and is joined to the welding equipment or resistance joint using between 1 and 4 joining pieces. The resistance joint can be made using either welding equipment or direct bonding (opposite electrodes) or bonding equipment or indirect welding (parallel groove). Prior to joining, the tongue can be cut to the desired length. After the union, the tabs may have holes drilled in two specific locations to facilitate flexing during assembly operations. The perforations can take place in the perforation station 60. In addition, two pieces of tape can be placed on the tab (for example, on either side of the electrode plate) to isolate and prevent shorts after cell closure. The tape can also add firmness to the tab / plate connection. The tape can be applied to the striking station 70. Alternatively, the conductive tab can be joined by ultrasonic bonding or welding. With reference to Figure 4, the electrode plate is present in the pre-treatment station 10 to pierce the surface of the electrode plate. The pretranslated electrode plate is presented in the ultrasonic cleaning station 20, and a small area is cleaned (for example 6 mm by 7 'mm). The cleaned or purified electrode plate is reinforced in the reinforcement station 30 in, for example, a three-stage process. After reinforcement, a conductive tab is attached to the electrode plate at the ultrasonic welding or bonding station 80. The ultrasonic bonding or welding consists of a combination of up or tip and an anvil in an optimized opening and performing the bonding by vibration. The electrode plate is present in the joining station perpendicular to the up or tip and anvil. A short piece of a conductive tongue stack (eg, 4mm by 18mm) is fed into a position on the reinforced, clean area of the electrode plate. The furnace is activated to compress the material and join it in place using ultrasonics. After joining, the tongue may have perforations in the piercing station 60 and tape may be applied in the striking station 70. The following examples are proposed to be illustrative and not limiting of the invention.

Example 1 Three groups of electrodes were constructed.

The group of electrodes 1 was prepared from a Retec foam (Bridgestone precursor), and does not include a reinforcing foam. The group of electrodes 2 was prepared from a Katayama foam and does not include a reinforcing foam. The group of electrodes 3 was prepared from a Katayama foam. The group of electrodes 3 was cleaned and reinforced with a piece of 5.5 mm by 16 mm of a 420 Retec foam, of resistance to belaying and resistance to the joining of the tongue. Twelve electrode foams from each of Groups 1, 2 and 3 were tested for the impedances and extraction strength (tensil) of the tongue. The tensile strength was determined using a Chatillion force standard. The separation speed was set at 5 mm / min and the force was recorded in kilograms. The impedances were tested using an HP4338A impedance meter and an impedence fixation. The impedence was recorded in milliohms. The results of the tests are summarized in Table 2. The non-reinforced electrodes (Groups 1 and 2) have higher impedance and lower tensile forces than reinforced electrodes (Group 3).

Table 2 Example 2 Eight groups of twenty electrodes (Groups A-H) were constructed and tested. The electrodes were pre-treated and purified by ultrasonic cleaning or purification. Groups A, C, E, and G were not reinforced. The groups after debugging in Groups B, D, F and H, the foam filler material (16 mm x 5.5 mm) was divided in half and pressed into the rinsed area using needle nose pliers. The tab was attached to the electrode using the ultrasonic bonding conditions listed in Table 3. twenty-one Table 3 The electrodes were tested for their impedance and extraction force (tensil) of the tongue. The tensile strength was determined using a Chatillion force standard. The separation speed was set at 5 m / min and the force was recorded in kilograms. The impedence test was performed using an HP4338A impedence meter and an impedence storage. The impedence was recorded in milliohms. The results are presented listed in Table 4.

Table 4 In general, the filled electrodes with foam reached tensile forces that were approximately 2 to 3 times higher than that of the non-filled electrodes. The impedence was reduced by a factor of approximately 17%. Other embodiments are within the claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property.

Claims (24)

1. A method for producing an electrode plate having a conductive tongue area, characterized in that it comprises the steps of: (a) piercing an area of the electrode plate with branch or elbow perforation plates, the opposite having high surface probes; (b) purifying or cleaning the resulting area to expose a porous substrate forming a conductive tongue area; (c) reinforce the exposed porous substrate; and (d) attaching a conductive tongue to the reinforced porous substrate.

2. The method of claim 1, characterized in that the step of reinforcement comprises the placement of a reinforcing material on the exposed porous substrate.

3. The method of claim 2, characterized in that the reinforcing step further comprises compressing the reinforcing material in the exposed porous substrate.

4. The method of claim 3, characterized in that the reinforcement material is double-folded.

5. The method of claim 3, characterized in that the joining step includes ultrasonic applications.

6. The method of claim 5, characterized in that the ultrasonics include an up or tip having raised surfaces and an anvil having a smooth surface.

7. The method of claim 3, characterized in that the joining step includes resistance joints.

8. The method of claim 7, characterized in that it further comprises the step of ultrasonic application to the reinforcing material compressed in the exposed porous substrate, prior to the joining step.

9. The method of claim 1, characterized in that it further comprises the step of drilling a hole in the conductive tongue after the joining step.

10. The method of claim 1, characterized in that it further comprises the step of striking the conductive tongue and the area of the conductive tongue after the joining step.

11. The method of claim 1, characterized in that the rinse step includes the application of ultrasonics to the resulting area.

12. The method of claim 11, characterized in that the ultrasonics are applied by a tip or even ultrasonic having a smooth surface and an anvil having raised surfaces.

13. The method of claim 1, characterized in that the conductive tongue is a single-layer conductive tongue.

14. The method of claim 1, characterized in that the conductive tongue is a double layer conductive tongue.

15. A method for producing an electrode plate having a conductive tongue area, characterized in that it comprises the steps of: (a) placing a reinforcement material on a porous substrate; and (b) attaching a conductive tongue to the reinforcing material on the porous substrate.

16. The method of claim 15, characterized in that it further comprises the step of compressing the reinforcing material on the porous substrate.

17. The method of claim 16, characterized in that it further comprises the step of piercing an area of an electrode plate with opposite branch or branch drill plates having probes of elevated surfaces, and debugging the resulting area to expose the substrate porous forming a conductive tongue area prior to the placement stage.

18. The method of claim 15, characterized in that the joining step includes the application of ultrasonics.

19. The method of claim 15, characterized in that the joining step includes the resistance joints.

20. The method of claim 19, characterized in that it further comprises the step of applying ultrasonic to the reinforcing material placed on the porous substrate prior to the joining step.

21. The method of claim 15, characterized in that it further comprises the step of drilling a gap in the conductive tongue, after the joining step.

22. The method of claim 15, characterized in that it further comprises the step of striking the conductive tongue and the area of the conductive tongue after the joining step.

23. An electrode plate having an implicit porous substrate coated with an electrochemically active material, characterized in that the electrode plate comprises a conductive tongue area substantially free of the active material and a conductive tongue attached to the conductive tongue area and a reinforcing material between the conductive tongue and the conductive tongue area.

24. An electrochemical cell, characterized in that it comprises a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode comprises an electrode plate having an implicit porous substrate, coated with an electrochemically active material, wherein the plate of the electrode has a conductive tongue area substantially free of the active material and a conductive tongue attached to the conductive tongue area and a reinforcing material between the conductive tongue and the conductive tongue area.