BATTERY CONNECTIONS AND METALLIZED FILM COMPONENTS IN ENERGY STORAGE DEVICES HAVING INTERNAL FUSES

Abstract

A lithium battery cell with an internal fuse component and including needed tabs which allow for conductance from the internal portion thereof externally to power a subject device is provided. Disclosed herein are tabs that exhibit sufficient safety levels in combination with the internal fuse characteristics noted above while simultaneously displaying pull strength to remain in place during utilization as well as complete coverage with the thin film metallized current collectors for such an electrical conductivity result. Such tabs are further provided with effective welds for the necessary contacts and at levels that exhibit surprising levels of amperage and temperature resistance to achieve the basic internal fuse result with the aforementioned sufficient conductance to an external device. With such a tab lead component and welded structure, a further improvement within the lithium battery art is provided the industry.

Claims

1. A process to produce a lithium ion battery comprising the steps of: a. providing an electrode having at least one metallized substrate with a coating of an ion storage material and a separate polymer substrate layer; b. providing a counterelectrode; c. layering said electrode and counterelectrode opposite each other with a separator component interposed between said electrode and said counterelectrode; d. providing a package material including an electrical contact component, wherein said contact includes a portion present internally within said package material and a portion present external to said package material; e. electrically connecting said electrical contact component with said metallized substrate wherein at least one metal layer of said metallized substrate is pressed through said polymer substrate layer of said metallized substrate to make an electrical connection with resistance less than 1 ohm with said electrical contact; f. introducing at least one liquid electrolyte with ions internally within said package material; and g. sealing said package material.

2. The method of claim 1 wherein said lithium battery further comprises an anode, a cathode, at least one separator present between said anode and said cathode, and at least one tab attached to said metallized substrate through said electrical connection of step “e”.

3. The method of claim 2 wherein said metallized substrate is at least one thin film current collector.

4. The method of claim 3 wherein said polymer substrate layer of said metallized substrate has a polymer substrate layer having a top and bottom surface, wherein a first metallized layer is attached to said polymer substrate top layer and a second metallized layer is attached to said polymer substrate bottom layer, wherein a tab is placed on said polymer substrate bottom layer, and wherein said at least one thin film current collector exhibits at least one weld divot therein such that at least a portion of said first metallized layer is in contact with said tab.

5. The method of claim 4 wherein said lithium ion battery further comprises at least one electrical connection tab attached through said at least one weld divot to at least one of said first metallized layer and said second metallized layer.

6. The method of claim 5, wherein said at least one weld divot associates with one of said anode and said cathode.

7. The method of claim 6, wherein at least one electrical connection tab is electrically connected through said at least one weld divot to said anode or said cathode.

8. The method of claim 7, wherein said at least one metallized thin film current collector includes up to 25 metallized film layers thereof.

9. The method of claim 8, wherein up to 25 electronic connection tabs are present.

10. The method of claim 1, wherein reinforcements are provided over said at least one weld divot.

11. The method of claim 8, wherein a plurality of metallized thin film current collectors are present and at least a plurality of said up to 25 metallized film layers present within said plurality of metallized thin film current collectors are extruded through adjacent metallized thin film current collectors to contact metallized film layers of other metallized thin film current collectors that are otherwise not in face-to-face contact with said extruded metallized film layers.

12. The method of claim 7 wherein a plurality of weld divots are present which exhibit a pattern that is fully populated, sparsely populated, partial grid staggered or partial grid aligned.

13. The method of claim 12 wherein at least one of said plurality of weld divots exhibits a shape selected from linear, a truncated pyramid, rounded pyramid and spherical.

14. The method of claim 8 wherein a plurality of weld divots are present which exhibit a pattern that is fully populated, sparsely populated, partial grid staggered or partial grid aligned.

15. The method of claim 14 wherein at least one of said plurality of weld divots exhibits a shape selected from linear, a truncated pyramid, rounded pyramid and spherical.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] FIG. 1 is a Prior Art depiction of the architecture of a wound cell, such as an 18650 cell.

[0068] FIG. 2 is a Prior Art depiction of the shrinkage as a function of temperature as measured by Dynamic Mechanical Analysis of several lithium ion battery separators, as measured according to NASA/TM-2010-216099 “Battery Separator Characterization and Evaluation Procedures for NASA's Advanced Lithium Ion Batteries,” which is incorporated herein by reference, section 3.5. Included are first generation separators (Celgard PP, Celgard tri-layer), 2nd generation separators (ceramic PE) and 3rd generation separators (Silver, Gold, Silver AR).

[0069] FIG. 3A is a Prior Art depiction of a scanning electron micrograph (SEM) of the cross section of a pouch cell that has undergone a nail penetration test. The layers are aluminum and copper as mapped by BEI (backscattered electron imaging). The nail is vertical on the left side. In each case, the aluminum layer has retreated from the nail, leaving behind a “skin” of aluminum oxide, an insulator.

[0070] FIG. 3B is a Prior Art depiction of a zoom in on one of the layers from the image shown in FIG. 3A. It shows a close up of the aluminum oxide layer, and also reveals that the separator had not shrunk at all and was still separating the electrodes to the very edge.

[0071] FIG. 4 is a depiction of the metallized film used in the current invention, where the thin layer of conductive material is on the outside, and the center substrate is a layer that is thermally unstable under the temperatures required for thermal runaway. This substrate can be a melting layer, a shrinking layer, a dissolving layer, an oxidizing layer, or other layer that will undergo a thermal instability at a temperature between 100° C. and 500° C.

[0072] FIG. 5A is a Prior Art depiction of a thick aluminum current collector, generally between 12-20 microns thick.

[0073] FIG. 5B is a depiction of the metallized film used in the current invention, showing a micron thick substrate with 1 micron of aluminum on each side. In the case of the inventive current collector, it is not capable of carrying the high currents associated with a short circuit, while the thick current art is and does.

[0074] FIGS. 6A and 6B show images of comparative examples 1-2, each after having been touched by the tip of a hot soldering iron. The comparative examples do not change after touching with a hot soldering iron.

[0075] FIGS. 7A, 7B, and 7C show images of examples 1-3, each after having been touched by the tip of a hot soldering iron. The examples 1-3 all exhibit shrinkage as described in this disclosure for substrates to be metalized.

[0076] FIGS. 8A, 8B, and 8C show images of examples 4-6, each after having been touched by the tip of a hot soldering iron. The example 4 exhibits shrinkage as described in this disclosure for substrates to be metalized. Example 5 has a fiber that will dissolve under heat in lithium ion electrolytes. Example 6 is an example of a thermally stable substrate that would require a thin conductive layer to function as the current invention.

[0077] FIGS. 9A, 9B, and 9C are SEMs at different magnifications in cross section and one showing the metalized surface of one possible embodiment of one current collector as now disclosed as described in Example 9. The metal is clearly far thinner than the original substrate, which was 20 microns thick.

[0078] FIGS. 10A and 10B are optical micrographs of a Comparative Examples 3 and 4 after shorting, showing ablation of the area around the short but no hole.

[0079] FIGS. 11A and 11B are optical micrographs of two areas of Example 14 after shorting, showing clear holes in the material caused by the high current density of the short.

[0080] FIG. 12 shows a depiction of the size and shape of a test strip for testing the current carrying capacity of the current collector utilized for Examples noted below.

[0081] FIG. 13 depicts a side perspective view of a single layer current collector with welded tab as one potentially preferred embodiment.

[0082] FIG. 14 depicts a side perspective view of a single layer current collector with taped tab as another potentially preferred embodiment.

[0083] FIG. 15 depicts a side perspective view of a single layer current collector with stapled tab as another potentially preferred embodiment.

[0084] FIG. 16 depicts a side perspective view of a single layer current collector with a single rounded fold therein and a taped tab as another potentially preferred embodiment.

[0085] FIG. 17 depicts a side perspective view of a single layer current collector with a double rounded fold therein and a taped tab as another potentially preferred embodiment.

[0086] FIG. 18 depicts a side perspective view of a single layer current collector with two parallel welded tabs as another potentially preferred embodiment.

[0087] FIG. 19 depicts a side perspective view of a single layer current collector with a single folded welded tab as another potentially preferred embodiment.

[0088] FIG. 20 depicts a side perspective view of a single layer current collector with a double rounded fold therein and a welded tab as another potentially preferred embodiment.

[0089] FIG. 21 depicts a side perspective view of a plurality of single layer current collectors each with a double rounded fold therein and a welded tab as another potentially preferred embodiment.

[0090] FIG. 22 depicts a side perspective view of a plurality of single layer current collectors each with a double rounded fold therein and two opposing welded tabs as another potentially preferred embodiment.

[0091] FIG. 23 depicts a side perspective view of a plurality of single layer current collectors in contact with a multiple Z-folded clamped tab as another potentially preferred embodiment.

[0092] FIG. 24 depicts a front perspective view of a composite current collector having a polymer substrate with two separate layers of metallized film and a single weld present.

[0093] FIG. 25 depicts a side view of a composite current collector having a polymer substrate and two separate layers of metallized film with a weld-connected tab attached thereto.

[0094] FIG. 26 is a high-magnification electron microscope cross-sectional view of a 100-micron length perspective of a welded current collector/polymer substrate composite (as in FIG. 25).

[0095] FIG. 26A is a 50-micron length perspective cross-sectional view of the composite of FIG. 26.

[0096] FIG. 27 depicts a side perspective view of a composite current collector having a polymer substrate and two separate layers of metallized film with a welded tab attached thereto.

[0097] FIG. 27A is a high-magnification electron microscope cross-sectional view of a 500-micron portion of the interface between the metallized film, polymer substrate, and tab as shown at the weld location in FIG. 27.

[0098] FIG. 27B is a 100-micron portion of the interface of FIG. 27A.

[0099] FIG. 28 depicts a side perspective view of a composite current collector having a polymer substrate and multiple layers of metallized film with a welded tab attached thereto.

[0100] FIG. 28A is a high-magnification electron microscope cross-sectional view of a 500 micron length perspective of the welded multi-layered metallized film/polymer substrate composite as shown in FIG. 28.

[0101] FIG. 28B is a 200-micron length perspective view of the composite of FIG. 28A.

[0102] FIG. 29 depicts a side exploded perspective view of multi-layer of a metallized film current collector welded to a tab.

[0103] FIG. 30 depicts a transparent side perspective view of a rigid plastic enclosure battery including a metallized film current collector and welded tab composite.

[0104] FIG. 31 depicts a side transparent view of a cylindrical battery with a jelly roll composite current collector with a welded tab.

[0105] FIG. 32 depicts a side perspective transparent view of a pouch enclosure battery including a metallized film current collector and welded tab composite.

[0106] FIG. 33 depicts a front perspective view of a multi-layer battery composite with multi layers of metallized film current collectors and welded tabs.

[0107] FIG. 33A is a different side perspective view of the battery composite of FIG. 33.

[0108] FIG. 34 depicts different potential embodiments of alternative weld structures in association with the metallized film current collectors and tabs herein.

[0109] FIG. 35 depicts a possible embodiment configuration of a fully populated weld grid structure.

[0110] FIG. 35A depicts a possible embodiment configuration of a sparsely populated weld grid structure.

[0111] FIG. 36 depicts a possible embodiment configuration of a partial staggered weld grid structure.

[0112] FIG. 37 depicts a possible embodiment configuration of a partial aligned weld grid structure.

[0113] FIG. 38 depicts a side perspective view of a current collector and tab battery composite having a top-side weld present.

[0114] FIG. 39 depicts a side perspective view of a current collector and tab battery composite having a film-side weld present.

[0115] FIG. 40 depicts a side perspective view of a single folded welded tab and current collector composite.

[0116] FIG. 41 depicts a partially exploded side perspective view of a multi-layer current collector and multi-tab composite.

[0117] FIG. 42 depicts a side perspective view of a composite of an electrode and welded tab including a separating fuse structure.

[0118] FIG. 43 depicts a side perspective view of a portion of a current collector/electrode/tab composite with tape for attachment.

[0119] FIG. 44 depicts a side perspective view of a battery composite having multi-layer current collectors and electrodes and a wound tape connection for a welded tab.

[0120] FIG. 45 depicts a side perspective view of a battery composite having multi-layer current collectors and electrodes and a clamped tape connection for a welded tab.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS AND EXAMPLES

[0121] The following descriptions and examples are merely representations of potential embodiments of the present disclosure. The scope of such a disclosure and the breadth thereof in terms of claims following below would be well understood by the ordinarily skilled artisan within this area.

[0122] As noted above, the present disclosure is a major shift and is counterintuitive from all prior understandings and remedies undertaken within the lithium battery (and other energy storage device) industry. To the contrary, the novel devices described herein provide a number of beneficial results and properties that have heretofore been unexplored, not to mention unexpected, within this area. Initially, though, as comparisons, it is important to note the stark differences involved between prior devices and those currently disclosed and broadly covered herein.

SHORT CIRCUIT EVENT EXAMPLES

Comparative Example 1

[0123] A cathode for a lithium iron phosphate battery was obtained from GB Systems in China. The aluminum tab was removed as an example of a commercial current collector, and the thickness, areal density and resistance were measured, which are shown in Table 1, below. The aluminum foil was then touched with a hot soldering iron for 5 seconds, which was measured using an infrared thermometer to have a temperature of between 500 and 525° F. There was no effect of touching the soldering iron to the current collector. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 6A. FIG. 5A provides a representation of the traditional current collector within such a comparative battery.

Comparative Example 2

[0124] An anode for a lithium iron phosphate battery was obtained from GB Systems in China. The copper tab was removed as an example of a commercial current collector, and the thickness, areal density and resistance were measured, which are shown in Table 1, below. The copper foil was then touched with a hot soldering iron in the same way as Example 1. There was no effect of touching the soldering iron to the current collector. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 6B. As in Comparative Example 1, FIG. 5A provides a representation of the internal structure of such a battery. The thickness of the current collector is significant as it is a monolithic metal structure, not a thin type as now disclosed.

Example 1

[0125] Polypropylene lithium battery separator material was obtained from MTI Corporation. The material was manufactured by Celgard with the product number 2500. The thickness, areal density and resistance were measured, which are shown in Table 1, below. The separator was then touched with a hot soldering iron in the same way as Example 1. Touching the thermometer to the current collector created a small hole. The diameter was measured and included in Table 1. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 7A.

Example 2

[0126] Ceramic coated polyethylene lithium battery separator material was obtained from MTI Corporation. The thickness, areal density and resistance were measured, which are shown in Table 1, below. The separator was then touched with a hot soldering iron in the same way as Example 1. Touching the soldering iron to the current collector created a small hole. The diameter was measured and included in Table 1. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 7B.

Example 3

[0127] Ceramic coated polypropylene lithium battery separator material was obtained from MTI Corporation. The thickness, areal density and resistance were measured, which are shown in Table 1, below. The separator was then touched with a hot soldering iron in the same way as Example 1. Touching the soldering iron to the current collector created a small hole. The diameter was measured and included in Table 1. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 7C.

Example 4

[0128] Aluminized biaxially oriented polyester film was obtained from All Foils Inc., which is designed to be used for helium filled party balloons. The aluminum coating holds the helium longer, giving longer lasting loft for the party balloons. The thickness, areal density and resistance were measured, which are shown in Table 1, below. The film was then touched with a hot soldering iron in the same way as Example 1. Touching the soldering iron to the current collector created a small hole. The diameter was measured and included in Table 1. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. A photograph was taken and included in FIG. 8A. Compared to the commercially available aluminum current collector of Comparative Example 1, this material is 65% thinner and 85% lighter, and also retreats away from heat, which in a lithium ion cell with an internal short would have the effect of breaking the internal short.

Example 5

[0129] Dreamweaver Silver 25, a commercial lithium ion battery separator was obtained. It is made from a blend of cellulose and polyacrylonitrile nanofibers and polyester microfibers in a papermaking process, and calendered to low thickness. The separator was then touched with a hot soldering iron in the same way as Example 1. Touching the soldering iron to the current collector did not create a hole. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. Compared to the prior art, comparative examples #3-5, these materials have the advantage that they do not melt or shrink in the presence of heat, and so in a lithium ion battery with an internal short, will not retreat to create an even bigger internal short. Such is seen in FIG. 8B.

Example 6

[0130] Dreamweaver Gold 20, a commercially available prototype lithium ion battery separator was obtained. It is made from a blend of cellulose and para-aramid nanofibers and polyester microfibers in a papermaking process, and calendered to low thickness. The separator was then touched with a hot soldering iron in the same way as Example 1. Touching the soldering iron to the current collector did not create a hole, as shown in FIG. 8C. The thickness, areal density and resistance were measured. The material was placed in an oven at 175° C. for 30 minutes and the shrinkage measured. The advantages of this separator compared to the prior art separators are the same as for Example 2.

TABLE-US-00001 TABLE 1 Areal Shrinkage Solder Tip Example Material Thickness Density Resistance (175 C.) Hole Size Comp Aluminum 30 μm  80 g/m.sup.2 <0.1 mOhm/square  0% No hole Example 1 Comp Copper 14 μm 125 g/m.sup.2 <0.1 mOhm/square  0% No hole Example 2 Example 1 PP 24 μm  14 g/m.sup.2 Infinite Melted 7.5 μm Example 2 PP ceramic 27 μm  20 g/m.sup.2 Infinite Melted 2 μm/1 μm Example 3 PE ceramic 27 μm  20 g/m.sup.2 Infinite Melted 5 μm/2 μm Example 4 Aluminized PET 13 μm  12 g/m.sup.2 6.3 Ohm/square 33%   2 μm Example 5 Fiber blend 27 μm  16 g/m.sup.2 Infinite  2% No hole Example 6 Fiber blend 23 μm  16 g/m.sup.2 Infinite  0% No hole

[0131] Comparative Examples 1-2 are existing current collector materials, showing very low resistance, high areal density and no response at exposure to either a hot solder tip or any shrinkage at 175° C.

[0132] Examples 1-3 are materials that have infinite resistance, have low areal density and melt on exposure to either 175° C. or a hot solder tip. They are excellent substrates for metallization according to this invention.

[0133] Example 4 is an example of an aluminized polymer film which shows moderate resistance, low areal density and shrinks when exposed to 175° C. or a hot solder tip. It is an example of a potential cathode current collector composite film according to this invention. In practice, and as shown in further examples, it may be desirable to impart a higher level of metal coating for higher power batteries.

[0134] Examples 5-6 are materials that have infinite resistance, have low areal density, but have very low shrinkage when exposed to 175° C. or a hot solder tip. They are examples of the polymer substrate under this invention when the thickness of the metallized coating is thin enough such that the metallized coating will deteriorate under the high current conditions associated with a short. Additionally, the cellulose nanofibers and polyester microfibers will oxidize, shrink and ablate at temperatures far lower than the melting temperatures of the metal current collectors currently in practice.

[0135] Example 5 additionally is made from a fiber, polyacrylonitrile, that swells on exposure to traditional lithium ion carbonate electrolytes, which is also an example of a polymer substrate under this invention such that the swelling will increase under heat and create cracks in the metalized coating which will break the conductive path, improving the safety of the cell by eliminating or greatly reducing the uniform conductive path of the current collector on the exposure to heat within the battery.

Example 7

[0136] The material utilized in Example 5 was placed in the deposition position of a MBraun Vacuum Deposition System, using an intermetallic crucible and aluminum pellets. The chamber was evacuated to 3×10.sup.−5 mbar. The power was increased until the aluminum was melted, and then the power set so the deposition rate was 3 Angstroms/s. The deposition was run for 1 hour, with four samples rotating on the deposition plate. The process was repeated three times, so the total deposition time was 4 hours. The samples were measured for weight, thickness and resistance (DC and 1 kHz, 1 inch strip measured between electrodes 1 inch apart), which are shown in Table 2 below. Point resistance was also measured using a Hioki 3555 Battery HiTester at 1 kHz with the probe tips 1″ apart. The weight of added aluminum was calculated by the weight added during the process divided by the sample area. This is divided by the density of the material to give the average thickness of the coating.

Example 8

[0137] A nonwoven polymer substrate was made by taking a polyethylene terephthalate microfiber with a flat cross section and making hand sheets at 20 g/m.sup.2 using the process of Tappi T206. These hand sheets were then calendered at 10 m/min, 2000 lbs/inch pressure using hardened steel rolls at 250° F. This material was metalized according to the process of Example 7, and the same measurements taken and reported in Table 8.

Example 9

[0138] Material according to Example 5 was deposited according to the process of Example 7, except that the coating was done at a setting of 5 Angstroms/second for 60 minutes. The samples were turned over and coated on the back side under the same procedure. These materials were imaged under a scanning electron microscope (SEM), both on the surface and in cross section, and the images are presented in FIGS. 9A, 9B, and 9C.

Example 10

[0139] Materials were prepared according to the procedure of Example 9, except the deposition on each side was for only 20 minutes.

Example 11

[0140] The polymer substrate of Example 8 was prepared, except that the sheets were not calendered. The deposition of aluminum is at 5 Angstroms/second for 20 minutes on each side. Because the materials were not calendered, the porosity is very high, giving very high resistance values with a thin coat weight. Comparing Example 11 to Example 8 shows the benefits of calendering, which are unexpectedly high.

TABLE-US-00002 TABLE 2 1 kHz Average Added DC 1 kHz point coating Sample weight Resistance Resistance resistance thickness Units g/m.sup.2 Ohms/ Ohms/ Ohms microns square square Example 7 3.5 0.7 0.5 0.1 1.3 Example 8 2.0 7 7 0.4 0.7 Example 9 2.2 0.2 0.8 Example 10 0.8 1.7 0.3 Example 11 0.8 100 0.3

Example 12

[0141] The aluminum coated polymer substrate from Example 9 was coated with a mixture of 97% NCM cathode material (NCM523, obtained from BASF), 1% carbon black and 2% PVDF binder in a solution of N-Methyl-2-pyrrolidone. The coat weight was 12.7 mg/cm2, at a thickness of 71 microns. This material was cut to fit a 2032 coin cell, and paired with graphite anode coated on copper foil current collector (6 mg/cm.sup.2, 96.75% graphite (BTR), 0.75% carbon black, 1.5% SBR and 1% CMC). A single layer coin cell was made by placing the anode, separator (Celgard 2320) and the NCM coated material into the cell, flooding with electrolyte (60 μL, 1.0M LiPF.sub.6 in EC:DEC:DMC=4:4:2 vol+2w. % VC) and sealing the cell by crimping the shell. To obtain adequate conductivity, a portion of the aluminum coated polymer substrate from Example 9 was left uncoated with cathode material and folded over to contact the shell of the coin cell, completing the conductive pathway. The cell was formed by charging at a constant current of 0.18 mA to 4.2 V, then at constant voltage (4.2 V) until the current dropped to 0.04 mA. The cell was cycled three times between 4.2 V and 3.0 V at 0.37 mA, and gave an average discharge capacity of 1.2 mAh.

Example 13

[0142] A cell was made according to the procedure and using the materials from Example 12, except the separator used was Dreamweaver Silver 20. The cell was formed by charging at a constant current of 0.18 mA to 4.2 V, then at constant voltage (4.2 V) until the current dropped to 0.04 mA. The cell was cycled three times between 4.2 V and 3.0 V at 0.37 mA, and gave an average discharge capacity of 0.8 mAh. Thus in this and the previous example, working rechargeable lithium ion cells were made with an aluminum thickness of less than 1 micron.

Comparative Example 3

[0143] The aluminum tab of Comparative Example 1, approximately 2 cm×4 cm was connected to the ground of a current source through a metal connector contacting the entire width of the sample. The voltage limit was set to 4.0 V, and the current limit to 1.0 A. A probe connected to the high voltage of the current source was touched first to a metal connector contacting the entire width of the sample, and then multiple times to the aluminum tab, generating a short circuit at 1.0 A. The tip of the probe was approximately 0.25 mm.sup.2 area. When contacted across the entire width, the current flowed normally. On initial touch with the probe to the tab, sparks were generated, indicating very high initial current density. The resultant defects in the current collector only sometimes resulted in holes, and in other times there was ablation but the current collector remained intact. In all cases the circuit remained shorted with 1.0 A flowing. A micrograph was taken of an ablated defect, with no hole, and is shown in FIG. 10A. The experiment was repeated with the current source limit set to 5.0, 3.0, 0.6 A, 0.3 A and 0.1 A, and in all cases the result was a continuous current at the test current limit, both when contacted across the entire width of the current collector and using the point probe of approximately 0.25 mm.sup.2 tip size.

Comparative Example 4

[0144] The copper tab of Comparative Example 2 of similar dimensions was tested in the same way as Comparative Example 3. When contacted across the entire width, the current flowed normally. On initial touch with the probe to the tab, sparks were generated, indicating very high initial current density. The resultant defects in the current collector only sometimes resulted in holes, and in other times there was ablation but the current collector remained intact. In all cases the circuit remained shorted with 0.8 A flowing. A micrograph was taken of an ablated defect, with no hole, and is shown in FIG. 10B. The experiment was repeated with the current source limit set to 5.0, 3.0, 0.6 A, 0.3 A and 0.1 A, and in all cases the result was a continuous current at the test current limit, both when contacted across the entire width of the current collector and using the point probe of approximately 0.25 mm.sup.2 tip size.

Example 14

[0145] The inventive aluminum coated polymer substrate material of Example 7 of similar dimensions was tested using the same method as Comparative Examples 3-4. When contacted across the entire width, the current flowed normally. In each case of the touch of the probe to the inventive current collector directly, the sparks generated were far less, and the current ceased to flow after the initial sparks, leaving an open circuit. In all cases, the resultant defect was a hole. Micrographs of several examples of the holes are shown in FIGS. 11A and 11B. The experiment was repeated with the current source limit set to 5.0, 3.0, 0.6 A, 0.3 A and 0.1 A, and in all cases the result a continuous flow of current when contacted through the full width connectors, and no current flowing through the inventive example when contacted directly from the probe to the inventive current collector example.

[0146] The key invention shown is that, when exposed to a short circuit as in Comparative Examples 3-4 and in Example 14, with the prior art the result is an ongoing short circuit, while with the inventive material the result is an open circuit, with no ongoing current flowing (i.e., no appreciable current movement). Thus, the prior art short circuit can and does generate heat which can melt the separator, dissolve the SEI layer, and result in thermal runaway of the cell, thereby igniting the electrolyte. The open circuit of the inventive current collector will not generate heat and thus provides for a cell which can support internal short circuits without allowing thermal runaway and the resultant smoke, heat and flames.

Examples 15 and 16 and Comparative Examples 5 and 6

[0147] Two metallized films were produced on 10 micron polyethylene terephthalate film in a roll to roll process. In this process, a roll of the film was placed in a vacuum metallization production machine (an example of which is TopMet 4450, available from Applied Materials), and the chamber evacuated to a low pressure. The roll was passed over heated boats that contain molten aluminum at a high rate of speed, example 50 m/min. Above the heated boats containing molten aluminum is a plume of aluminum gas which deposits on the film, with the deposition rate controlled by speed and aluminum temperature. A roll approximately 500 m long and 70 cm wide was produced through multiple passes until the aluminum coating was -300 nm. The coating process was repeated to coat the other side of the film, with the resultant product utilized herein as Example 15 (with the inventive current collector of FIG. 4 a depiction of that utilized in this Example). Example 16 was thus produced in the same way, except the metal in the boat was copper (and with the depiction of FIG. 5B representing the current collector utilized within this inventive structure). The basis weight, thickness and conductivity of each film were measured, and are reported below in Table 3. The coating weight was calculated by subtracting 13.8 g/m.sup.2, the basis weight of the 10 micron polyethylene terephthalate film. The “calculated coating thickness” was calculated by dividing the coating weight by the density of the materials (2.7 g/cm.sup.3 for aluminum, 8.96 g/cm.sup.3 for copper), and assuming equal coating on each side. Comparative Example 5 is a commercially obtained aluminum foil 17 microns thick. Comparative Example 6 is a commercially obtained copper foil 50 microns thick. Comparative Example 7 is a commercially obtained copper foil 9 microns thick.

TABLE-US-00003 TABLE 3 Calculated Basis Coating Thick- DC coating Sample Weight Weight ness Resistance thickness Units g/m.sup.2 g/m.sup.2 Microns Ohms microns Example 15 17 3 11 0.081 0.5 Example 16 24 10 11 0.041 0.5 Comparative 46 17 Example 5 Comparative 448 50 Example 6 Comparative 81 9 Example 7

[0148] Example 15, Example 16, Comparative Example 5 and Comparative Example 6 were subjected to a further test of their ability to carry very high current densities. A test apparatus was made which would hold a polished copper wire with radius 0.51 mm (24 AWG gauge) in contact with a current collector film or foil. The film or foil under test was grounded with an aluminum contact held in contact with the film or foil under test, with contact area >1 square centimeter. The probe was connected in series with a high power 400 W resistor of value 0.335 ohms, and connected to a Volteq HY3050EX power supply, set to control current. The current collector to be measured was placed in the setup, with the polished wire in contact with the surface of the current collector at zero input current. The current was increased in 0.2 ampere increments and held at 30 seconds for each increment, while the voltage across the resistor was measured. When the voltage dropped to zero, indicating that current was no longer flowing, the sample was shown to fail. Each of Example 15, Example 16, Comparative Example 5 and Comparative Example 6 were tested. Example 15 failed at a 7 A (average of two measurements). Example 16 failed at 10.2 A (average of two measurements). Neither of Comparative Example 5 nor Comparative Example 6 failed below 20 A. Both Example 15 and Example 16 showed holes in the current collector of radius >1 mm, while neither of the Comparative Examples 5 or 6 showed any damage to the foil. In this example test, it would be advantageous to have a current collector that is unable to carry a current of greater than 20 A, or preferably greater than 15 A or more preferably greater than 12 A.

[0149] In another test, meant to simulate using these inventive current collectors as a tab connecting the electrode stack of a cell to the electrical devices in use (either inside or outside the cell), Examples 15 and 16 and Comparative Examples 5 and 6 were subjected to a current capacity test along the strip. To prepare the samples for the test, the current collectors were cut into the shape shown in FIG. 12, which consists of a strip of material that is four centimeters by on centimeter (4 cm×1 cm), with the ends of the strip ending in truncated right isosceles triangles of side 4 cm. Each of the triangles of the test piece was contacted through a piece of aluminum with contact surface area >1 cm. One side was connected through a 400 W, 0.335 ohm resistor, and this circuit was connected to a Volteq HY3050EX power supply. The voltage was measured across the resistors to measure the current, and the piece was shown to fail when this voltage dropped to zero. For each test, the piece was connected with the power supply set to zero current, and then increased in 0.2 A increments and allowed to sit for 30 seconds at each new voltage, until the sample failed and the current flowing dropped to zero. The test was configured so that the metallized current collectors could be measured with contact either on one side, or on both sides of the metallized current collector. The currents at failure are shown below in Table 4. For materials tested in a 4 cm×1 cm strip, it would be advantageous to provide an internal fuse by limited the amount of current that can flow to be below 20 A, or preferably below 15 A, or more preferably below 10 A, each with either single or double-sided contact.

TABLE-US-00004 TABLE 4 Single Sided Double Sided Sample Failure Voltage Failure Voltage Units V V Example 15 2.7 4.5 Example 16 24 10 Comparative No failure No failure Example 5 below 20 A below 20 A Comparative No failure No failure Example 6 below 20 A below 20 A

Examples 17 — 19 and Comparative Example 8

[0150] Cells were made by coating standard foil current collectors and the metallized PET film current collectors from Examples 15 and 16 with electrode materials. NMC 523 cathode materials were prepared using BASF NMC523 (97%), carbon black (2%) and PVDF (1%) in NMP solvent, and coated on the aluminum current collector (15 micron aluminum current collector) and Example 15 were at a basis weight of 220 g/m.sup.2, corresponding to a cathode loading density of 3.3 mAh/cm.sup.2. Anode materials were prepared by using graphite BTR-918S (94%), carbon black (5%) and PVDF (1%) in NMP solvent, and coating on the copper current collector (18 micron copper current collector) at 118 g/m.sup.2, corresponding to an anode loading density of 4.0 mAh/cm.sup.2. Four double sided cathodes were prepared, and three double sided anodes and two single sided anodes. These were stacked with Celgard 2500 separator to form small pouch cells, which were then filled with electrolyte and sealed with designed capacity 1 Ah. Four types of cells were made by different combinations of foil materials, and the capacity measured at C/10 and C/5 (that is, 0.1 A and 0.2 A). The cells were formed by charging at 100 mA to 4.2 V, and held at 4.2 V until the current dropped to 10 mA. The fully formed cells were then weighed, and tested for capacity by discharging at C/10, then charging at C/10 and discharging at C/5. These results are shown in Table 5, below.

TABLE-US-00005 TABLE 5 Cathode Anode Current Current Cell C/10 C/5 Sample Collector Collector Weight Capacity Capacity Units Grams mAh mAh Comparative Al Foil Cu Foil 27 924 615 Example 8 Example 17 Example 15 Cu Foil 26.8 1049 751 Example 18 Al Foil Example 16 24.7 1096 853 Example 19 Example 15 Example 16 24.7 1057 848

[0151] Thus, it has been shown that the Examples provided above exhibit the desirable thickness, metal coating, and conductivity results needed to prevent thermal runaway within an electrolyte-containing battery, thereby providing not only a much safer and more reliable type, but one that requires far less internal weight components than ever before, without sacrificing safety, but, in fact, improving thereupon.

[0152] As noted above, the ability to not only provide such a thin current collector (as an internal fuse within a lithium battery article) but also the necessary benefits of a tabbed structure to ensure generated voltage is transferred external of the subject battery cell, is accorded within this disclosure. Additionally, the ability to further utilize the beneficial thin structures of the current collector as above lends itself to any number of myriad configurations within the confines of the subject battery article itself, potentially generating cumulative power levels all with the beneficial internal fuse component(s) in place. Such are discussed in greater detail within FIGS. 12-22.

[0153] FIG. 13 shows a single thin film current tab/collector 600 with a metallized film layer 614 and a lower non-metal layer 616. A conducting tab 610 (to lead to the external power transfer component of a battery) is provided as well, aligned perpendicularly to the collector, and connected thereto with welds 612. FIG. 14 shows a similar current collector 620 but with a tab 622 present with tape 624 connecting the tab 622 to the collector 634 for such a conductive purpose. As above, the tab/current collector 620 has a metallized film layer 626 and a lower non-metal layer 632. The tape component 622 is provided on the outer surface 628 of the tab and leading to the non-metal layer 626 of the current collector, provided a shear strength adhesive quality for the tab to remain secured and in suitable manner for conduction purposes. FIG. 15 provides a different tab/collector 640 showing a different manner of connecting a tab 642 to a single thin current collector 648 (with a metallized film layer 644 and a lower non-metal layer 650), connecting the two components through the utilization of conducting staple components 646.

[0154] FIG. 18 likewise includes a flat tab/current collector 750 with the same type of upper 758 and lower surface 762 as above. The tab 752, 754, in this instance, is provided as two parallel structures with contact with both the top 758 and lower surfaces 760 of the current collector 762. Such a tab 752, 754 includes welds 756 for connection to and with both surfaces 758, 760. FIG. 17 shows a similar structure 780 to FIG. 16, but with a single folded tab 794 in place that is in contact with both surfaces 788, 790 of the current collector 792 through welds 786 with two extended prongs 782, 784 of the folded tab 794 leading therefrom.

[0155] Such flat current collector structures allow for a typical battery structure with a compact battery structures (such as in FIG. 1, for instance). FIG. 16 shows a single fold 710 tab/current collector 700 with a single taped tab 702 attached thereto the metallized film surface 712 (which covers, as above, the non-metal layer 708). In this manner, the single fold 710 current collector 704 imparts the capability of an increase in power generation within the battery cell as a result, albeit with the need for a slight increase in battery size from the flat structure. FIG. 17 depicts a double folded 732 tab/current collector 720 utilizing the same thin structure collector 724. Such a double fold 732 thus further provides the ability to connect the two sides 726, 728 of the current collector 724 that might otherwise be electrically insulated by the polymer film situated between the two electrically conducting layers. The tab 722 attaches at the collector surface 730 for such a double fold 732 conductivity purpose. FIG. 20 shows a welded 804 tab 802 to a double folded 810 tab/current collector 800, thus exhibiting the same ability to connect electrically isolated layers 808, 812 as above as part of the collector 806, but with safer welds 804 in place to more reliably and more potentially effective for power transfer purposes. FIG. 21 thus shows a composite tab/multiple collectors structure 820 with a plurality (here five) of such double rounded folded 856 current collectors 826,828, 830, 832, 834 with metallized film layers 858, 860, 862, 864, 866 and lower non-metal layers 846, 848, 850, 852, 854, connected in a series for even more ability to connect electrically isolated layers for conductivity through a single tab 822 with welds 824 connecting for conductance with the top double rounded folded collector 826. The welded tab 822 stays in place strongly for improved reliability purposes, as well. A second, opposite, welded 906 tab 904 is provided in FIG. 22 with such a multiple multi rounded fold 938 current collector array 908, 910, 912, 914, 916 in place, as well. Such a tabs/collectors structure 900 allows for increased power generation without necessitating weight of volume increases for the subject battery cell through the two tabs 902, 904 configured and connected with the two outer collectors 908, 916, as noted previously. Metallized film layers 940, 942, 944, 946, 948 are, as above, provided with opposing non-metal layers 928, 930, 932, 934, 936 are present as with such other collector examples. Lastly, as yet another non-limiting example tab/collector structure 960, a multi-Z-fold 972 tab 962 clamped to a series of parallel flat thin current collectors 964, 966, 968, 970 (here four)(as described above), with metallized film layers 974, 978, 982, 986 and lower non-metal layers 976, 980, 982, 984, again, to provide a different manner of generating cumulative power in a series, albeit with flat thin current collectors 964, 966, 968, 970 (acting as multiple internal fuses).

[0156] Such structures of FIGS. 13-23 thus allow for different external connections to the internal fuse components of a standing lithium battery.

[0157] FIG. 24 shows a single-welded composite of a thin film current collector 1010 having a middle polymer substrate 1015 and a top metallized film 1012, a bottom metallized film 1014, a weld divot 1020 with a weld direction 1018 indicated, and an interface 1022 of the top 1012 and bottom metallized films 1014. The polymer substrate 1015 has been manipulated outwardly from the weld divot 1020 to allow for the interface 1022 connection between top 1012 and bottom 1014 metallized films. Careful control of the welding parameters are needed to move the polymer without also destroying the metal, in general using less power and more pressure. While exact power and pressure must be determined experimentally based on the exact configuration of welding nodes, metal layer thickness, polymer thickness and metal and polymer material types, it is generally true that less power and more pressure than for a pure metallic weld will yield the desired configuration as shown in this and other figures in this disclosure. FIG. 24 shows the profile of a single ideal node. In practice, many nodes will be present and can be configured with different cross sections and node configurations as depicted in FIGS. 34, 35, 35A, 36, and 37. The desirable effect is to maximize the interface 1022 by varying the node geometry and processing parameters such as power, frequency and pressure, if for ultrasonic welding, or temperature and pressure if for thermal welding.

[0158] FIG. 25 shows a welded composite 1030 of a tab 1032 and thin film current collector (1010 of FIG. 24) with a top metallized film 1012, polymer substrate 1015, and bottom metallized film 1014. As with FIG. 24, the top-applied weld 1020 moves the polymer substrate 1015 for the metallized films 1012, 1014 to contact. The tab 1032 likewise contacts with the top film 1012 in relation to the weld direction 1034 for connection between the tab 1032 and current collector (1010 of FIG. 24) allowing for conductivity from the bottom film 1014 through the top film 1012 to the tab 1032.

[0159] To show an actual potential embodiment in actual structural definition, FIGS. 26 and 26A show microphotographs (100- and 50-micron lengths, respectively) of weld interfaces of such a composite of metallized film 1012, polymer substrate 1015 and bottom film 1014. The weld direction 1018 presses the metallized film 1012 to and bottom film 1014 in such a manner as to produce a connection between the two materials 1013 through the polymer substrate 1015. This connection 1013 permits percolation between the top film 1012 and bottom film 1014 to facilitate and optimize the conductivity from the metallized film 1012 to a tab ((1042 in FIG. 27, for example) for improved battery operation.

[0160] FIG. 27 shows a tab/current collector composite 1040 with the same current collector as in FIG. 24 (1010) and a tab 1042 connected with the bottom film layer 1014. With the top weld 1020 applied to the current collector top film 1012, the polymer substrate 1015 is moved to allow for the top 1012 and bottom 1014 films to interface, thus permitted conductivity between the metallized films 1012, 1014 and the tab 1042. FIGS. 27A and 27B show photomicrographs of the interface of the weld interface between the bottom film and the tab, showing the clear delineations therein. FIG. 27B particularly shows the tab and bottom film welded layer interface with metallic debris present from the metallized filmi during the weld process. FIG. 28 shows a tab/current collector composite 2040 with a similar top thin film metallized film collector 2042 to the current collector as in FIG. 24 (1010) and a tab 2044 connected with a bottom film layer of a multi-layered metallized film structure 2046 (with polymer substrate in-between each individual layer). Such layers may be extruded to form such a multiple-layer structure 2046 on top of the tab 2044 itself. The layers 2046, including the top layer 2042, are of the same thin film structure as that in FIG. 24 (1010). The multiple layers 2042, 2046 manipulated through a weld divot 2048 to connect the multiple layers 2042, 2046 together at a weld interface 2049. Additionally, with the multiple thin film current collector layers 2042, 20436, the weld divot 2048 may be applied in such a manner as to generate a graduated contour 2047 surrounding the full weld divot 2048 to facilitate the full weld pressure application through the multiple current collector layers 2042, 2046. With such a contour 2047, there is further generated a raised peripheral edge 2045 at the top edge thereof the weld divot 2048. The resultant composite 2040 thus allows for conductivity between all of the metallized film collector layers 2042, 2046 to the tab 2044 for further utilization within a battery for external power transfer. FIGS. 28A and 28B provide photomicrographs of the same composite structure of FIG. 28. Noticeable are the top current collector layer 2042 and the multiple layers below 2046 of such thin film structures. The weld interface 2049 connects such multiple collector layers 2042, 2046 to the tab 2044. A visible contour 2047 surrounding the weld with a raised peripheral edge 2047 is also present. In FIG. 28B the weld interface 2049 shows the presence of film collector portions within the polymer substrate to allow for conductivity between not only the top thin film collector layer 2042 and the tab 2044, but also the multiple collector layers 2046 with the tab 2044. As above, such a composite 2040 allows for a battery transfer capability from a cell externally through such a tab 2044.

[0161] FIG. 29 provides a different possible composite 1050 of tab 1054, a top metallized film 1052 and multiple layers of metallized film current collectors 1058 connected to each other through a weld 1056, thus allowing for conductivity of such metallized films 1058, 1052 through to the tab 1054.

[0162] FIGS. 30, 31, and 32 show different types of battery devices utilizing the welded tab to a thin current collector power cell. FIG. 30 shows a battery 1060 with a rigid plastic container 1062, the power cell 1066 and the connected external tab 1064 for further connection to a device (not illustrated). FIG. 31 shows a cylindrical battery 1070 with a container 1072, power cell (electrode/current collector) 1074 and extending tab 1076. FIG. 32 shows a pouch battery 1080 with a pouch container 1082, a power cell 1084, and connected external tab 1086, again, for contact with an external device (not illustrated).

[0163] FIGS. 33 and 33A show power cell composites 1090 having multiple tabs 1098, multiple electrode/current collector layers 1096, a top tab 1094, and a top electrode current collector layer 1092, all welded together as described herein.

[0164] FIGS. 34, 35, 35A, 36, and 37 pertain to different potential embodiments of weld anvil structures and patterns/configurations for utilization within and imparting weld divot shapes and structures (three-dimensional) within target tab/power cell composites. FIG. 34 shows a number of different possible anvil structure embodiments 1100. One is a linear 1102 structure having a rectangular structure in three dimensions. Also shown is a truncated pyramid three-dimensional structure 1108 (with a narrowing slope from a square edge to a smaller square top), a rounded pyramid structure 1106, and a spherical structure 1104 (with ribbed peripheries). Such three dimensional anvils 1100 thus may be pressed with ultrasound, heat, or just pressure, within a composite current collector (1010 of FIG. 24) and/or collector and tab (1020 of FIG. 25) to impart the needed interfaces between current collector films and tabs. FIG. 35 thus shows one possible embodiment of repeating truncated pyramid structures 1110 in a full grid to apply welds in like pattern. FIG. 35A shows another possible embodiment of a grid of sparsely populated truncated pyramid anvils 1120 for the same purpose. FIGS. 36 and 37 relate to uniformity of grids of truncated pyramids 1130, 1140 for patterned application to target composites (staggered as compared with aligned). Such three-dimensional anvils thus allow for the manipulation of polymer substrates (1015 of FIG. 24, for instance) in relation to pressing a top film (1012 of FIG. 24) downward to contact with a bottom film (1014 of FIG. 24) in relation to a finished weld (1020 of FIG. 24) for connection and conductivity purposes, as discussed and described herein.

[0165] FIGS. 38 and 39 show different potential embodiments of a top weld (FIG. 38) and a bottom weld (FIG. 39). FIG. 38 shows a welded composite 1150 with a tab 1154, metallized film(s) 1152, a top weld direction 1154, and a finished weld 1156 connecting the metallized film(s) 1152 with the tab 1154. FIG. 39 shows a welded composite 1160 with a tab 1164m metallized film(s) 1162, a bottom weld direction 1164, and a finished weld 1166 connecting the metallized film(s) 1162 with the tab 1164.

[0166] FIG. 40 shows a possible embodiment of a welded composite 1170 with a single folded tab 1174 having a single bend 1175, a current collector/electrode 1172, multiple welds 1176 between the tab 1174 and the current collector/electrode 1172, and an end weld 1178 for the tab to attach to itself. FIG. 41 shows a possible embodiment of a welded composite 1180 of staggered metallized film current collectors 1182 and staggered tabs 1184 with multiple welds 1186 for attachment of such collectors 1182 and tabs 1184 together. In this configuration, each metal face of each current collector 1182 comes in face-to-face contact with at least one of the tabs 1184. FIG. 42 shows a possible embodiment of a welded composite 1190 with an electrode/current collector 1192 connected to a fuse area 1198 that is welded to a tab 1194 within a limited weld area 1196 at the fuse area 1198. These embodiments provide some showing of the versatility available in relation to such welding techniques with thin film current collectors.

[0167] FIGS. 43, 44, and 45 provide depictions of possible embodiments in relation to reinforcements to supplement such welding operations within power cell composites. FIG. 43 shows a welded composite 1200 having opposing electrodes 1202, 1204 with a welded tab 1208, a reinforcement tape 1206, and a further overlap 1210 for such increased reinforcement capabilities. FIG. 44 shows a multi-film welded composite 1220 with multiple thin films 1224, a top layer thin film 1222, and a welded tab 1226. A reinforcement tape 1228 is applied at the tab weld (not shown) again to increase the applied pressure for reinforcement capability over such a weld area. FIG. 45 shows a multi-film welded composite 1230 having multiple thin films 1234, a top layer thin film 1232, and a welded tab 1236. Applied over a weld interface is a clamp 1238 to reinforce such weld(s) (not illustrated). Thus, reinforcement of such welds may be accomplished through a number of different possible alternatives.

[0168] With such unique and heretofore unexplored welds, patterns thereof, different weld types themselves, even reinforcements for increased safety, reliability, and effectiveness, there is provided a novel approach to utilizing thin metallized film current collectors within lithium ion (and like) batteries, capacitors, power cells, etc., for effective power transfer and reduced thermal runaway potential.

[0169] Having described the invention in detail it is obvious that one skilled in the art will be able to make variations and modifications thereto without departing from the scope of the present invention. Accordingly, the scope of the present invention should be determined only by the claims appended hereto.