CN112997342A

CN112997342A - Battery connector and metallized film assembly in an energy storage device with internal fuse

Info

Publication number: CN112997342A
Application number: CN202080006037.9A
Authority: CN
Inventors: 布莱恩·G·莫林; 卡尔·C·胡
Original assignee: Sotria Battery Innovation Group
Current assignee: Sotria Battery Innovation Group; Soteria Battery Innovation Group Inc
Priority date: 2019-03-22
Filing date: 2020-03-20
Publication date: 2021-06-18
Also published as: JP2022527140A; AU2020245238A1; KR20210143234A; WO2020197981A1; CA3132870A1; EA202192436A1; EP3861583A1

Abstract

The present invention provides a lithium battery cell having an internal fusible member and including the necessary tabs that allow electrical conductivity to be transferred from its internal portion to the outside to power a given device. The tab provided by the present invention, in combination with the internal fusible features described above, exhibits a sufficient level of safety while exhibiting tensile strength to maintain position during use and completely cover the thin film metallized current collector for such conductivity results. Such tabs are also provided with an effective solder for the necessary contacts and provide a current and temperature resistance performance that exhibits a surprising level, thereby achieving a basic internal meltdown result and the above-mentioned sufficient electrical conductivity to the outside. Using such tab lead assemblies and welded structures provides the industry with further improvements in lithium batteries.

Description

Battery connector and metallized film assembly in an energy storage device with internal fuse

Technical Field

The present technology relates to improvements in structural components and physical characteristics of lithium battery articles. For example, standard lithium ion batteries are, for example, prone to certain phenomena related to short circuits and thus experience high temperature occurrences and eventual combustion. It has been found that structural problems associated with battery assemblies lead to such problems. The improvements provided by the present invention include utilizing thin metalized current collectors (e.g., aluminum and/or copper), high shrinkage materials, materials that become non-conductive upon exposure to high temperatures, and combinations thereof. Such improvements give the ability to withstand certain defects (dendrites, accidental surges, etc.) in the target lithium battery itself by providing internal fuses on the surface within the target lithium battery to prevent undesirable high temperature consequences due to short circuits. Articles of manufacture and methods of using the same including such improvements are also included in the present invention.

It is of particular interest and importance to provide a lithium battery cell that includes the necessary tab leads to allow conduction of electrical conductivity from its interior outward to power the target device, which can be an important arrangement due to the thin nature of the electrodes, and the two sides of the electrode material may not be conductive to each other. In the present invention, a tab is provided that exhibits a sufficient level of safety in combination with the above-described internal fuse characteristics while exhibiting tensile strength that remains in place during use and is fully covered by a thin film metallized current collector to achieve such conductive results. Such tabs are further provided with an effective weld for the necessary contacts that exhibits the current levels and high temperature resistance to achieve substantial internal fusing results and with surprising levels of electrical conductivity sufficient to external equipment as described above. Further improvements are provided in the lithium battery industry by such tab lead assemblies and welded constructions.

In addition, the internal fuse development of the present disclosure exhibits extremely thin current collector structures that further allow for their potential for repeated folding within a single battery cell. This folding possibility provides the ability to connect both sides of the current collector, which in addition can be electrically insulated by a polymer layer located between the two conductive layers, without requiring excessive internal weight and/or cell volume requirements. Seemingly, the folded current collector maintains internal fuse characteristics while allowing such power increases, potentially allowing any number of power increases in any number of size cells without the excessive weight and volume requirements described above, thereby creating a new battery article for different purposes with a targeted high power level and as high a safety benefit as possible.

Background

Lithium batteries are still popular around the world as a power source in a wide variety of products. From rechargeable power tools to electric vehicles to ubiquitous cell phones (e.g., tablet computers, handheld computers, etc.), lithium batteries (of different ion types) are used as the primary power source due to reliability, the above-mentioned rechargeability and long service life. However, the use of such widely used power supplies presents certain problems, some of which have proven to be increasingly severe. Notably, safety issues have emerged in which certain defects in such lithium batteries cause a tendency to develop an ignition potential during a short circuit event, whether due to initial manufacturing issues or time-related degradation issues. Basically, it has been found that internal defects in the conductive material can generate undesirably high heat within such cell structures and ultimately cause fire. As a result, from handheld computer devices (samsung Galaxy Note 7, as a notorious situation) to whole airplanes (boeing 787), certain products that use lithium batteries have been banned from sale and/or use until solutions have been offered for damaged lithium batteries used therein and therewith (even to the extent that in certain regions any airplane is banned from using samsung Galaxy Note 7). Even the electric vehicle Tesla (Tesla) production line presents a significant problem for lithium battery packs, which causes headline news that expensive cars explode like a fireball due to battery problems. Thus, extensive recalls or general prohibitions associated with such lithium battery problems still exist to date, and there is an urgent need to overcome such problems.

These problems are primarily due to manufacturing issues, whether the individual battery components being made or such components themselves being configured as individual batteries. By careful observation, lithium batteries are currently made from six major components: a negative electrode material; positive and negative electrode current collectors (e.g., aluminum foil) coated with a negative electrode material; a positive electrode material; a positive electrode current collector (e.g., copper foil) coated with a positive electrode material; a separator, typically made of a plastic material, located between each negative and positive electrode layer; and an electrolyte that acts as a conductive organic solvent that saturates other materials, thereby providing a mechanism for conducting ions between the negative electrode and the positive electrode. These materials are typically wound together in cans (as shown in prior art fig. 1) or stacked together. There are many other configurations that can be used for such battery production purposes, including pouch cells, prismatic cells, button cells, cylindrical cells, wound prismatic cells, wound pouch cells, to name a few. These batteries, when properly fabricated and handled gently, can provide energy for a variety of applications for thousands of charge-discharge cycles without any significant safety hazard. However, as mentioned above, certain events, particularly certain defects, can lead to internal short circuits between internal conductive materials, leading to heating and internal thermal runaway, which are known to be the ultimate cause of fire in such lithium batteries. As mentioned above, such events may also be caused by internal defects, including the presence of metal particles within the battery, burrs on the current collector material, fine dots or holes in the separator (whether included during or caused during subsequent processing), misalignment of the battery layers (undesired electrical conductivity created by leaving "openings" open), external debris penetrating into the battery (such as road debris impacting a moving vehicle), crushing and/or instability of the battery cell itself (e.g., due to an accident), charging of the battery cell in an enclosed space, and the like. Generally, these types of defects are known to result in a small electron conduction path between the negative and positive electrodes. When such an event occurs, if the battery is subsequently charged, such a conductive path may result in discharge of the battery cell, which ultimately generates excessive heat, thereby damaging the battery structure and compromising the underlying devices powered thereby. In combination with the presence of flammable organic solvent materials as the battery electrolyte, which are often necessary for battery operability, this excessive heat has been shown to cause ignition thereof, ultimately resulting in a very dangerous situation. Such problems are difficult to control, at least once initially, and have resulted in serious injury to the consumer. By providing a battery that delivers electrical energy without damaging the flammable organic electrolyte in this manner, such a potentially catastrophic situation can certainly be avoided.

The generation of excessive heat internally may further cause shrinkage of the plastic separator, thereby dislodging it from the cell, separating it, or otherwise increasing the short circuit area within the cell. In this case, a larger exposed short circuit area within the battery may result in sustained current flow and increased heat therein, resulting in high temperature events that can cause significant damage to the battery cells, including bursting, venting, or even flames and fires. Such damage can be particularly problematic due to the possibility of fire and worse results that can occur quickly and can cause the battery and potentially underlying device to explode, thereby also presenting a significant hazard to the user.

Lithium batteries (of various types) are particularly prone to problems associated with short circuits. As noted above, typical batteries tend to exhibit increased discharge rates under high temperature exposure, sometimes leading to uncontrolled (runaway) combustion and ignition as noted above. Because of these possibilities, certain regulations have been put into effect to manage the actual use, storage, or even transportation of such battery items. Of course, the ability to implement an appropriate protocol to prevent a runaway event associated with a short circuit is very important. However, problems still remain as to how to actually solve such problems, particularly when parts production is offered from countless suppliers and many different locations around the world.

Some have milled attempts to provide suitable and/or improved separators as a means of helping to mitigate the potential for such lithium batteries to catch fire. Plastic films with low melting points and/or shrinkage rates appear to produce higher potentials for such battery fire events. Thus, the general idea is to include certain coatings on such separator materials without reducing their electrolyte separation capacity during actual use. Thus, for example, ceramic particles have been used as polypropylene and/or polyethylene film coatings as a means of increasing the dimensional stability (e.g., increasing the melting point) of such films. A binder polymer is also included as a component for improving cohesion between ceramic particles and adhesion to a plastic film (film). However, in practice, the heat gain imparted to the overall film structure of the ceramic particle coating has been found to be relatively low, thus making the main factor of such separator problems the actual separator material itself.

As a result, separator materials that are more thermally stable than polyethylene and polypropylene porous membranes (which constitute the base layer of such typical ceramic coated separators) have been designed and implemented, at least to some extent. These low shrinkage, dimensionally stable separators exhibit shrinkage of less than 5% when exposed to temperatures of at least 200 ℃ (up to 250 ℃, 300 ℃, or even higher), far superior to the high shrinkage exhibited by bare polymer films (greater than about 40% at 150 ℃) and the high shrinkage of ceramic coated films (greater than 20% at 180 ℃) (such shrinkage tests are provided in prior art figure 2). Such low shrinkage materials may change the thermal degradation mechanism inside the target battery cell when a short circuit occurs. Generally, when a short circuit occurs in such a battery cell, heat is always generated. If the separator does not shrink due to such a short circuit event, heat will continue to be generated and "built up" until another material within the cell degrades. This phenomenon has been simulated by industry standard nail penetration testing. For example, even though a separator including a para-aramid fiber and exhibiting shrinkage stability up to 550 ℃ was used, the target test cell exhibited a tendency of short circuit and had unique internal results. After such treatment, a more careful study of the cell was conducted in which the cell was opened, the excess electrolyte was evaporated, the cell was filled with epoxy resin, and then cut in a perpendicular fashion to the pins, leaving it in the cell. Scanning electron microscopy images were then performed using back-scattered electron imaging (BEI), which enables mapping of different cell elements to show the effect of this nail penetration activity. These are shown in prior art fig. 3A and 3B.

In prior art fig. 3A, it is noted that the copper layer is always closer to the nail than the aluminum layer. It is also noted that the high stability separator is still intact between the electrodes. Prior art figure 3B shows a higher magnification of the end of one aluminum layer showing it ending with a broken gray matter layer. This was studied with BEI and the result showed that the material formed was in fact alumina, an insulating ceramic. These evidences lead to the conclusion that: when the separator itself is thermally stable, the aluminum current collector oxidizes, effectively breaking the circuit (with the result that any short circuits cease once insulating alumina is formed). Once the circuit is broken, the current will stop flowing and no longer generate heat, reversing the process, which can lead to thermal runaway if the membrane is less stable.

However, this possible solution is limited to replacement with only a membrane with higher shrinkage characteristics. Although such simple solutions seem valuable, there are still other manufacturing procedures and specific components (such as ceramic coated separator types) that have been widely used and may be difficult to replace with accepted battery products. Thus, despite the obvious benefits of utilizing and including thermally stable separators, undesirable battery ignition can still occur, particularly when the ceramic coated separator product is considered safe for such purposes. It has therefore been determined that in addition to utilizing such a high thermally stable separator material, there is at least one other separate internal cell structural mechanism that can remedy or at least reduce the chance of heat generation due to internal short circuits. In such a case, the complete internal circuit is stopped due to the fact that an internal fuse is formed, and the occurrence of a short circuit in such a battery cell does not cause harmful high-temperature damage. However, to date, no technology has been proposed in the field of lithium batteries that can easily solve these problems. The present invention provides such a highly desirable solution that makes lithium battery cells extremely safe and reliable in multiple markets.

Of further particular interest is the consideration of properly allowing the conduction of charge from the target lithium ion battery to an external power source. Typically, this is accomplished by utilizing tabs that contact and are secured to the current collectors, or possibly secured to the negative and positive current collectors in some manner, to provide the desired external electrical conductivity characteristics. The tab surface serves as a contact to such internal battery components and, for the purpose of such electrical conductivity, extends through the contact point to the exterior of the cell housing. Thus, the tabs must remain in place and cannot be disengaged from the current collector and allow undamaged access to the external power source without being internally displaced or disengaged. Since there is no disclosure in the field of lithium ion batteries of such thin film current collectors, there has also been no attempt to ameliorate or optimize such tab connection problems. Of course, standard types of tabs are well known and are connected to the large current collectors of standard cells; however, this does not provide any consideration for protecting the thin film current collector function (e.g., internal fuse) while still providing an overall dimensionally stable result to prevent cell failure due to structural leakage. Therefore, in the current lithium ion battery field or industry, there is no discussion or disclosure of any such effect. However, the present invention overcomes this paradigm and provides results heretofore unexplored and/or unknown in the relevant industry.

Disclosure of Invention

A significant advantage of the present invention is that a mechanism can be provided by the structural assembly to interrupt the conductive path, stop or greatly reduce the current flow that may generate heat within the target cell when an internal short circuit occurs. Another advantage is the ability to provide such a protective structural form in a lithium battery cell, which also provides beneficial weight and cost improvements for the manufacture, transport and application of the entire battery. Thus, another advantage is that the internal fuse structure is created and maintained within the target cell until it needs to be activated. Another advantage is to provide a lighter weight battery by utilizing a thin film based current collector that can prevent thermal runaway during a short circuit or similar event. Another advantage is the ability to utilize flammable organic electrolyte materials within the cell without any significant potential for ignition during a short circuit or similar event. Another significant advantage is the ability to provide an adequate conductive tab member that is welded or otherwise in contact with the internal fuse current collector, particularly both its upper and lower surfaces. Another advantage is the ability to form folds within the thin current collector assemblies disclosed herein to allow for the cumulative generation of electricity in multiple current conducting internal structures in series, thereby providing robust desired cell results without the need for excessive weight or volume measurements.

Accordingly, the present disclosure may include an energy storage device comprising a negative electrode, a positive electrode, at least one polymer or fabric separator between the negative electrode and the positive electrode, an electrolyte, and at least one current collector in contact with at least one of the negative and positive electrodes; wherein a negative or positive electrode is interposed between at least a portion of the current collector and the separator, wherein the current collector comprises a conductive material coated on a polymeric material substrate, and wherein the current collector ceases to conduct at an exposed short circuit contact point at an operating voltage of the energy storage device, wherein the voltage is at least 2.0 volts. An example is a contact point with a current density of 0.1A/mm²Wherein the tip size is 1mm²Or less. Of course, for larger cells, the required threshold current density may be higher, and the battery may only be at least 0.3A/mm²The current density of (A) stops conducting, e.g., at least 0.6A/mm²Even at least 1.0A/mm². Such coated polymeric material substrates should also exhibit a total thickness of up to 25 microns, as described in more detail below. Methods of utilizing such beneficial current collector assemblies in energy storage devices(whether or not it is a battery such as a lithium ion battery, a capacitor, etc.) is also encompassed within the present invention. Further, such a thin film current collector battery article may be further provided with at least one tab in contact with the base thin film current collector by 2 to 50 evenly spaced and evenly sized welds extending along the length of the current collector, wherein the at least one tab is placed on the thin film such that the at least one tab has an exposed top surface and a bottom surface in contact with the cover surface of the thin film current collector, wherein the welds indicate the location of the conductive material passing from the exposed upper surface of the tab through the tab to the cover surface of the thin film current collector. The present invention also includes the use of multiple current collectors as described above and folded to provide individual power generation regions connected in series within a single battery article.

Another aspect of the invention may be an energy storage system comprising an anode, a cathode, at least one separator between the anode and the cathode, and an electrolyte. At least one thin film current collector may be in contact with at least one of the negative electrode and the positive electrode. The current collector may include a conductive material coated on a non-conductive material substrate. The current collector may cease conducting electricity at the shorted contact point at an operating voltage of the energy storage device. The voltage may be at least 2.0 volts. At least one tab may be attached to the at least one thin film current collector. A connection device may be configured to attach the tab to the current collector. The connection means may exhibit electrical contact with the exposed surface of the tab and the thin film current collector. Either the negative electrode or the positive electrode may be interposed between at least a portion of the thin film current collector and the separator.

In some or all embodiments of the invention, the connecting means may be selected from the group consisting of welding, tape, staples, inserted metal strips, z-folded metal strips, conductive adhesive and clamps.

In some or all embodiments of the invention, the connection means may consist of 2-50 connectors distributed over the entire current collector to allow uniform current flow from the electrode material to the tab.

In some or all embodiments of the invention, the current collector may be folded to allow face-to-face contact between opposing sides of the current collector.

In some or all embodiments of the invention, the membrane may be a polymer, a non-woven fabric, a textile, or a ceramic.

In some or all embodiments of the invention, the non-conductive material substrate may be a polymer film.

In some or all embodiments of the invention, the electrolyte may be a combustible organic electrolyte.

In some or all embodiments of the present invention, the tabs may be a first tab contacting an upper surface of the current collector and a second tab contacting a lower surface of the current collector. The first and second tabs may be parallel.

In some or all embodiments of the invention, the tab may be folded over the current collector such that the first prong of the tab is in contact with the upper surface of the current collector and the second prong of the tab is in contact with the lower surface of the current collector. The first prong and the second prong may be parallel.

In some or all embodiments of the invention, the current collector may have a double-folded configuration to create two electrically insulating layers.

In some or all embodiments of the invention, the current collector may be a plurality of current collectors connected in series, wherein the tab is attached to a last current collector of the plurality of current collectors.

Some or all embodiments of the invention may include a second tab attached to a first current collector of the plurality of current collectors. The tab and the second tab may be parallel.

In addition, greater current densities can be supported in a short time or in a very small tipped probe. In this case, a large current such as 5 amps or 10 amps, or even 15 amps may be connected for a short period of time (e.g., less than 1 second, or less than 0.1 second, or even less than 1 millisecond (0.001 second)). Within the present invention, while it is possible to measure larger currents, the transfer time for such currents is short enough that the total energy transferred is very small and insufficient to generate enough heat to cause a thermal runaway event within the target cell. For example, it is known that a short circuit in a conventional architecture cell produces 10 amps of current at 4.2 volts for 30 seconds, with the result that 1200 joules of energy is delivered to a small localized area within such a cell. This result measurement can raise the temperature of the 1 gram portion of the target cell by about 300 c, which is high enough to not only melt the conventional separator material present therein, but also to place the entire cell in a runaway thermal state. As described above, this may result in the electrolyte material present therein being damaged as described above, as well as potential damage to not only the target battery but also the device or appliance in which the target battery is present and the surrounding environment. Thus, there is certainly the possibility of shortening the duration of the short circuit and reducing the relative level of delivered energy obtained within the short circuit to a low joule measurement, possibly avoiding thermal runaway (and the potential disasters associated therewith), if not completely prevented. For example, reducing the short circuit residence time within the current collector to below 1 millisecond, may then reduce the delivered energy to 0.04 joules (corresponding to 1200 joules described above, e.g., resulting in an excessive temperature of 300 ℃ or higher in a 1 gram local area of the target cell). This low level produces only a 0.01 c temperature increase in this 1 gram localized region of the cell, thereby preventing thermal runaway within the target cell and within the entire cell.

It is therefore another significant advantage of the present invention to provide a current collector for a battery that greatly limits the transit time of the current level applied to the target current collector surface by the probe tip (in order to controllably simulate the effects of internal manufacturing defects, dendrites or external events that cause internal shorting of the target battery) to less than 1 second, preferably less than 0.01 second, more preferably less than 1 millisecond, most preferably, perhaps even less than 100 microseconds, especially for larger currents. Of course, such current will be limited by the internal voltage of the battery, which may be 5.0V, 4.5V, or 4.2V or less, e.g., 4.0V or 3.8V, but a minimum of 2.0V.

This novel current collector component is in fact the reverse of those commonly used and found today in lithium batteries (and other types of batteries) and energy storage devices. The standard current collectors provided are conductive metal structures, such as aluminum and/or copper panels, the thickness of which is believed to provide some type of protection to the overall cell or like structure. These typical current collector structures are designed to provide the maximum possible conductivity within weight and space constraints. However, it appears that this idea has in fact been misunderstood, particularly because thick panels commonly used in energy storage devices today actually not only strike arcs when a short circuit occurs, but also greatly exacerbate runaway temperatures if and when such a situation occurs. Such a short circuit may be caused, for example, by dendrite formation within the separator. Such malformations, whether caused during or during manufacture or due to prolonged use, thereby resulting in a loss of potential, may allow voltage to be inadvertently transferred from the negative electrode to the positive electrode, resulting in an increase in current, which in turn results in an increase in temperature at the location where such a condition occurs. In fact, one potential cause of short circuits that lead to defects is the formation of burrs on the edges of these thick typical current collectors when they are slit or cut by worn blades during repeated manufacturing processes of multiple products (as is common today). However, it has been repeatedly analyzed and understood that standard current collector materials only exhibit a spark propensity and allow for a temperature increase, and further allow the current present in such a situation to continue through the device, allowing for unrestricted generation and movement, with no means to prevent an increase in current and thus an increase in temperature level. This problem directly leads to uncontrolled high temperature results; without any internal means to stop the situation, it is often urgent that a fire may occur and eventually the equipment may be burned. Furthermore, the current path (charging direction) of a standard current collector remains fairly static before and during a short circuit event, exhibiting essentially the same potential shift of charge as would be expected from the positive electrode to the negative electrode and then moving horizontally in one particular direction along the current collector. However, in the event of a short circuit, this current path cannot prevent or at least reduce or delay such charge movement, in other words, allows a rapid discharge in an uncontrolled manner in the entire battery itself. The high temperatures associated with such rapid discharges can lead to the catastrophic problems described above (fires, explosions, etc.).

Conversely, and again, it is highly unexpected and counter-intuitive for typical structures and configurations of lithium batteries that at least the use of the current collectors of the present invention results in extremely high current density measurements (due to the reduced thickness of the conductive elements) and prevents charge movement (e.g., no charge direction) when a short circuit occurs. In other words, with the current collector components disclosed herein having certain structural limitations, the current density is increased to such an extent that the resistance level creates an extremely high but contained high temperature occurrence associated with short circuits. Thus, this resistance level allows the conductive material (e.g., aluminum and/or copper, by way of example only) to receive a short circuit charge, but due to the structural form provided herein, the conductive material reacts immediately with respect to such high temperature, localized charges. In combination with other structural considerations of such current collector components, namely the actual lack of dimensionally stable polymeric material in contact with such conductive material layers, which are immediately oxidized at the point of charging thereon, leaving behind two non-conductive materials, such as alumina or copper oxide. For such transient non-conductive material generation, the short circuit charge appears to dissipate as there is no direction available for its movement. Thus, with the current collector described now, the occurrence of an internal short circuit causes an immediate stop of the current, effectively utilizing the immediate high temperature consequences caused by such a short circuit, thus creating a barrier against further charge movement. In this way, the absence of further current in the entire body of the energy storage device (of course, in connection with a short circuit) attenuates such undesirable events to such an extent that the short circuit is completely suppressed, with no consequences of uncontrolled current or high temperature occurring thereafter, and perhaps most importantly, the current collector remains viable for its initial and protective purposes, since the presence of locally non-conductive material does not result in any significant reduction in current when the energy storage device (battery, etc.) is operating in the intended manner. In addition, the relatively small area created by the non-conductive material leaves a large surface area, etc., on the current collector for further utilization without the need for repair, replacement, or other remedial measures. Ensuring that this does not always occur, of course, but as is now disclosed, the likelihood of such high temperature hazards and damage events occurring without certain precautions and corrective measures remains substantially well above the generally accepted levels. Thus, the entire current collector becomes a two-dimensional electrical fuse due to its instability under short circuit conditions, destroying the current collector's ability to conduct current at the point of short circuit by exploiting the transient effects of large currents, thereby preventing potentially catastrophic high currents associated with short circuits.

This allows the advantage, with respect to the new obtainment of current collectors that can be provided, that they can have a similar end result through many different options. In any of these alternative configurations, the current collector surfaces described herein act as internal fuses within the target energy storage device (e.g., lithium battery, capacitor, etc.). In each case (alternatively), however, there is a current collector comprising a polymer layer which is metallized on one or both sides thereof, and at least one metallized side is in contact with the negative or positive electrode of the target energy storage device. Then, alternatively, the total thickness of the entire metallized (coated) polymer substrate of the current collector is less than 20 microns, possibly preferably less than 15 microns, and possibly more preferably less than 10 microns, with resistance measurements less than 1 ohm/□, possibly preferably less than 0.1 ohm/□, and possibly more preferably less than 50 ohms/□. Typical current collectors may exhibit these characteristics, but are much heavier than those made with reinforced polymer substrates, and do not have the inherent safety advantages of the presently disclosed variations. For example, a copper foil having a thickness of 10 μm has a weight of 90g/m². However, the weight of the copper foil may be as low as 50g/m²Or even as low as 30g/m²Or even less than 20g/m²All while providing sufficient electrical performance for battery operation. However, in this alternative structure, the very thin component also allows for a short circuit to be made withThe metal coating reacts and the localized area of metal oxide immediately blocks any further current flow from moving from it due to excessive temperatures caused by current spikes during short circuits, relative to the total resistance level produced.

Another possible alternative to this new current collector is to provide a temperature dependent metallic (or metallized) material that will shrink during short circuit due to heat sources or that will easily degrade to a non-conductive material at specific material locations (e.g., as one example, from an aluminum current collector to alumina, and as mentioned indirectly in a different way above). In this way, the current collector becomes thermally fragile, in sharp contrast to the aluminium and copper current collectors used today which are fairly thermally stable at high temperatures. As a result, alloys of metals with lower intrinsic melting temperatures may degrade at lower short circuit current densities, thereby improving the safety advantages of the disclosed lithium-based energy devices. Another option is to produce the current collector by coating a layer of conductive material (e.g. copper or aluminium) on a fibre or film that exhibits higher shrinkage at lower temperatures. Examples of these include thermoplastic films having a melting temperature below 250 ℃ or even below 200 ℃, and may include polyethylene terephthalate, nylon, polyethylene, or polypropylene, as non-limiting examples. Another possible way to achieve this result is to make the current collector by coating a layer of conductive material (e.g. copper or aluminium) on a fiber or film which swells or dissolves in the electrolyte when the material is heated to a temperature higher than the operating temperature of the battery but lower than the temperature which could lead to thermal runaway. Examples of such polymers that are capable of swelling in lithium ion electrolytes include polyvinylidene fluoride and polyacrylonitrile, but there are other polymers well known to those skilled in the art. Another way to implement this alternative internal e-fuse generation process is to coat the substrate with a metal that can be oxidized under heat (e.g., aluminum) having a total metal thickness that is much lower than the total metal thickness typically used for lithium batteries. For example, very thin aluminum current collectors used today may be 20 microns thick. A total coating thickness of less than 5 microns will result in faster circuit interruption, while a coating thickness of less than 2 microns or even less than 1 micron will result in faster circuit interruption. Another way to achieve the interruption of the conductive path is to provide the current collector with limited conductivity that will degrade at high current densities around the short circuit, similar to the degradation found today in commercial fuses. This may be achieved by providing the current collector with a resistivity of greater than 5 milliohms/□ or 10 milliohms/□, or possibly more preferably greater than 20 milliohms/□, or greater than 50 milliohms/□, possibly more preferably levels. These measurements may be on one or both sides of the two-sided coated material. For batteries designed for high power, the use of current collectors of different resistivity may also be chosen differently, which may use a relatively low resistance compared to batteries designed for lower power and higher energy; and/or a relatively high resistance may be used. Yet another way to achieve the interruption of the conductive path is to provide a current collector that oxidizes to a non-conductive material at temperatures well below that of aluminum, thereby rendering the current collector inert in the area of the short circuit before the degradation of the separator. Certain aluminum alloys will oxidize more rapidly than the aluminum itself, and these alloys can cause conductive paths to degrade faster or at lower temperatures. As a possible alternative, any type of metal having such thin layer capacity and exhibiting electrical conductivity may be used, including but not limited to: gold, silver, vanadium, rubidium, iridium, indium, platinum, etc. (basically, by using very thin layers, the costs associated with the use of such metals can be greatly reduced without sacrificing conductivity, and still allow protection from thermal runaway potentials during short circuits or similar events). Also, different metal layers may be used, or even discrete areas of metal deposited in or as separate layer components may be utilized. Of course, one side of such a coated current collector substrate may also comprise a different metal species than the opposite side, and may in contrast also have a different layer thickness.

One way to improve the electrical performance of a battery would be to ensure that the coated current collector includes two coated sides that are electrically conductive, thereby allowing electrical conductivity from one side coating to the other on the surface. For example, such a result is not possible with uncoated polymer films. However, it has been recognized that such a double-sided electrical conductance flux (conductive through put) may be achieved, as one non-limiting example, by a non-woven fabric comprising a percentage of conductive fibers, or a non-woven fabric loaded with a conductive material, or a non-woven fabric made of a conductive material (such as carbon fibers or metal fibers), or a non-woven fabric containing fibers coated with a conductive material (such as fibers having a metal coating on the surface) as described above. Another type of novel thin current collector material that exhibits top-to-bottom conductivity may be a film that becomes conductive, for example, by utilizing an inherently conductive material (e.g., a conductive polymer such as polyacetylene, polyaniline, or polyvinylpyrrolidine) or via loading with a conductive material (e.g., graphite or graphene or metal particles or fibers) during or after film fabrication. In addition, another possible double-sided thin current collector material is a polymer substrate with small perforations during metallization and its sides coated with metal (aluminum or copper). This conductivity from side to side will not require as much conductivity as a conductive coating.

Thus, such alternative configurations that achieve the same current collector results and physical properties on the surface include: a) wherein the total thickness of the coated polymeric substrate is less than 20 microns and the electrical resistance is less than 1 ohm/□; b) the current collector comprises a conductive material coated on a substrate comprising a polymeric material, wherein the polymeric material exhibits a thermal shrinkage of at least 5% at 225 ℃; c) wherein the current collector metallized polymer material swells in the electrolyte of the battery, such swelling increasing as the polymer material is heated; d) wherein the total thickness of the current collector conductive material when applied to the polymeric substrate is less than 5 microns; e) wherein the current collector has an electrical conductivity of 10 milliohms/□ to 1 ohm/□; and f) wherein the metallized polymer substrate of the current collector exhibits a porosity of up to 60%. It is also within the scope of the present invention to utilize any of these alternative configurations in an energy storage device having a separator that exhibits a thermal shrinkage of less than 5% after 1 hour at 225 ℃. The overall utilization (method of use) of this type of energy storage device (battery, capacitor, etc.) is also encompassed by the present invention.

While the primary advantage of the present invention is to enhance the safety of the battery, there are other advantages as described above, including reducing the weight of the overall energy storage device by reducing the metal weight associated with such current collector assemblies. Again, the use of thin metallized coated polymer layers (particularly with low dimensional stability) for current collectors in such battery articles is entirely counter productive. The current practice of the industry remains this idea: a relatively large number of actual metal and/or insulator components are required to achieve the desired protective effect (especially from potential short circuit events). It has now been unexpectedly appreciated that such paradigm is not only incorrect, but that an effective remedy to the problem of short circuits inside lithium batteries, etc., is to reduce rather than increase the amount of metal and couple it to a thermally unstable substrate. Thus, again not only is it very unexpectedly appreciated that a thin metal layer with such an unstable base layer provides the ability to resist and effectively prevent discharge events during a short circuit, the overall effect is not only a safer and more reliable result, but also a substantial reduction in the overall weight and volume of such an assembly. Thus, the unexpected benefit of improved properties with reduced weight and volume requirements in energy storage products (batteries, etc.) is more in line with the industry than was originally understood.

By way of further explanation, the density is 2.7g/cm ³20 microns thick aluminum of 54g/m². However, a polypropylene film (density 0.9 g/cm) at 10 μm thickness³) The weight of the same metal coated at 1 μm was 11.7g/m². This weight reduction of the current collector may reduce the weight of the entire target energy storage device (e.g., battery), thereby increasing mobility, increasing fuel mileage or electrical range, and generally increasing the value of mobile electrical applications.

In addition, due to the high strength of the film, the above examples can also be made thinner, for example, 11 microns in total thickness, again reducing the volume of the cell compared to 20 microns, effectively increasing the energy density. In this way, current collectors having a total thickness of less than 15 microns, preferably less than 12 microns, more preferably less than 10 microns, and most preferably less than 8 microns, can be manufactured and used for such purposes and functions.

Since the volume resistivity of aluminum is 2.7X 10^-8Ohm.m, copper volume resistivity of 1.68X 10^-8Ohm-meter, thin coatings can be made less than 1 ohm/□ or less than 0.5 ohm/□, or even less than 0.1 ohm/□ or less than 0.05 ohm/□. These conductive coatings may have a thickness of less than 5 microns, preferably less than 3 microns, more preferably less than 2 microns, and possibly most preferably even less than 1 micron. It is very contrary that when standard materials commonly used in the market contain 10 microns or more of metal, the proper performance can be obtained by using much less metal. In fact, most of the metals present in a typical storage device are included to provide suitable mechanical properties for high speed and automated processing. One of the advantages of the present invention is the use of a much lower density polymer material to provide mechanical properties, reducing the metal thickness to a level that improves battery safety, since the current collector cannot carry the high current densities that are caused by internal electrical shorts and that lead to thermal runaway, smoke generation and fire set-up, which are highly dangerous.

In addition, these conductive layers may be made of multiple layers. For example, the aluminum layer may be a base layer coated with a thin layer of copper. In this way, bulk conductivity can be provided by aluminum which is lightweight, inexpensive, and can be easily deposited by vapor deposition techniques. Copper can provide additional conductivity and passivation to the negative electrode without adding significant additional cost and weight. This example is given for illustrative purposes only, and one skilled in the art can provide many other multilayer conductive structures, any of which are excellent embodiments of the present invention.

These thin metal coatings will generally result in higher electrical resistance compared to that in conventionally practiced aluminum or copper current collectors, thereby providing the salient features of the present invention in comparison. Such novel suitable current collectors may be made to be greater than 10 milliohms/□, preferably greater than 20 milliohms/□, more preferably greater than 50 milliohms/□, and perhaps most preferably even greater than 100 milliohms/□.

In addition, batteries made with the above-described heat-weak current collectors may become safer if the separator has high thermal stability, such as may exhibit low shrinkage at high temperatures, including shrinkage of less than 5% after exposure to a temperature of 200 ℃ for a hour, preferably after exposure to 250 ℃ for an hour, and possibly more preferably after exposure to a temperature of 300 ℃ for an hour. The existing separator is made of polyethylene with a melting temperature of 138 ℃ and polypropylene with a melting temperature of 164 ℃. As shown in fig. 2, these materials show greater than 50% shrinkage at 150 ℃; such a result is too high for using a thin current collector as described in the present invention. To remedy this problem, it has been recognized that it is necessary to utilize certain membranes that shrink less than 50%, even less than 30% or less than 10% at 150 ℃ as measured according to NASA TM-201O-216099, section 3.5. Even ceramic coated membranes show significant shrinkage at relatively moderate temperatures, with complete fracture or shrinkage of greater than 20% at 180 ℃. Accordingly, it is desirable to utilize a separator that does not break and does not shrink by more than 20%, more preferably by more than 10%, under exposure conditions of 180 ℃ (at least) when measured according to the same test standard. The most preferred embodiment is to utilize a separator that shrinks less than 10% when exposed to temperatures of 200 ℃ or 250 ℃, or even 300 ℃.

For any of these metallized substrates, it is desirable to have a low thickness to facilitate increasing the energy density of the cell. Such thickness can be achieved by using any means, including calendering, compression, hot pressing or even ablating material of the surface in a manner that reduces the overall thickness. These thinning processes may be performed before or after metallization. It is therefore desirable to have a total thickness of the metallized substrate of less than 25 microns, preferably less than 20 microns, more preferably less than 16 microns, and perhaps most preferably less than 14 microns. Commercial polyester films have been realized with thicknesses of up to 3 microns and even less 1.2 microns. These types may be used as suitable substrates and allow the total thickness of the current collector to be less than 10 microns, preferably less than 6 microns, and more preferably less than 4 microns. Such ultra-thin current collectors (with suitable conductivity as described above and throughout) may allow for higher energy densities and have improved safety performance, a result that has not been explored to date.

It is also desirable that these metallized substrates have a light weight. This may be achieved by using, by way of example only, low density polymeric materials such as polyolefins or other low density polymers including polyethylene, polypropylene and polymethylpentene. It can also be achieved by having an open cell structure in the substrate or even by using a low basis weight substrate. Thus, the density of the polymer used in the substrate may be less than 1.4g/cm³Preferably less than 1.2g/cm³And may more preferably be less than 1.0g/cm³. Furthermore, the areal density of the substrate material may be less than 20g/m²Preferably less than 16g/m²And may most preferably be less than 14g/m². In addition, the areal density of the metal-coated polymeric substrate material can be less than 40g/m²Preferably less than 30g/m²More preferably less than 25g/m²And may most preferably be less than 20g/m²。

Porous polymer substrates can also achieve low weight. However, the porosity cannot be too high for these materials, since this leads to low strength and large thickness, so that the objectives involved cannot be achieved in practice. Thus, such substrate materials exhibit a porosity of less than about 60%, preferably less than 50%, and possibly more preferably less than 40%. There is no lower limit to porosity since solid materials can be used for this type of metal coated current collector.

High strength is required to process the material into a battery at high speed. This can be achieved by using elongated polymers (from elongated fibers, or from uniaxially or biaxially elongated films).

As illustrated in the following description of the drawings, an energy storage device (whether a battery, capacitor, supercapacitor, or the like) is made and therefore provided in accordance with the present invention, wherein at least one current collector exhibiting characteristics associated with no significant current movement after a short circuit contacts the positive electrode, the negative electrode, or two separate current collectors contact both the positive and negative electrodes, and a separator and electrolyte are present and sealed in a standard (suitable) energy storage device container. In most cases, the positive electrode, the negative electrode, the container, the electrolyte, and in some cases, the separator assembly are standard assemblies. However, as disclosed herein, the current collectors utilized herein and herein are not only novel and unexplored in the art, but are also counter-productive as actual energy storage device components. This is again described in more detail below.

As mentioned above, in order to reduce, if not completely prevent, the chance of thermal runaway within a battery cell (particularly of the lithium ion rechargeable type, although other types are possible), a means is required to have any short circuits therein occurring substantially for a short period of time, to reduce the residence time within or on the current collector, and to ultimately exhibit a final energy level of minimum joule level (i.e. less than 10, preferably less than 1, most preferably less than 0.01). Then, in this case, and as previously mentioned, there is an electrical path from the negative electrode to the positive electrode and through the separator (thin conductive current collector in place) and the organic combustible electrolyte, it has been observed that the low-weight, thin current collector allows such ideal results, in particular in terms of rogue charge dissipation on the current collector surface and no significant temperature rise that would cause the electrolyte components to ignite soon. Surprisingly and without being bound by any particular scientific explanation or theory, it is believed that the conductive properties of the thin current collector material allow the short circuit charges to reach only the thin conductive current collector and immediately create a short duration high energy event that reacts between the metal on the surface of the current collector and the charges themselves, forming a metal oxide at that particular point on the surface of the current collector. The metal oxide provides insulation for further electrical activity and the applied current dissipates instantaneously, leaving a potential deformation inside the current collector itself, but is present to prevent any further charge activity at that particular location. Thus, the remaining current collector is intact and may provide the same capabilities as before, further providing such protection against any more potential short circuits or similar phenomena. As an example, in the case of thermal runaway in prior art battery products, negative electrode, positive electrode, current collectorAnd the separator includes an electrical path that generates heat and provides a spark to ignite the cell associated with the short circuit. Thus, there is further the effective danger that the ion-transporting combustible electrolyte allows for the high temperature consequences associated with such unexpected charges. Essentially, the heat generated at the current collectors of the prior art causes an initial electrochemical reaction within the electrolyte material, eventually leading to uncontrolled ignition of the electrolyte material itself. The inventive current collectors disclosed herein are therefore particularly valuable when used in battery cells comprising such flammable electrolytes. For example, such electrolytes typically include organic solvents such as carbonates, including propylene carbonate, ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, and the like. These electrolytes are typically present as mixtures of the above materials, and may be present with other solvent materials, including various types of additives. These electrolytes also have a lithium salt component, an example of which is lithium hexafluorophosphate LiPF₆. Such electrolytes are preferred in the battery industry, but as mentioned above may indeed lead to hazardous situations. Also, such inventive current collectors associated with other battery components significantly and surprisingly remedy these problems.

One way in which such a current collector would exert its utility is in the following tests. The current source with voltage and current limits may be set to a voltage limit similar to the operating voltage of the energy storage device in question. The current can then be adjusted and the current collector tested in both configurations. In a first configuration, a short strip of current collector of known width contacts two metal connectors that contact the entire width of the sample. The current limit of the current source can be increased to see if there is a limit on the ability of the material to carry current, which can be measured as the total current divided by the width, to give a result in units of a/cm, designated as the horizontal current density in the present invention. The second configuration is to contact the ground of the current source with one of the full-width metal contacts and then touch the tip of the probe (about 0.25 mm) along the position of the current collector strip²). If the current is too high, it will burn out the local area and no current will flow. If the current is not to the current collectorToo high, full current up to the current source limit will flow. The result is an A/mm²Is the current limit in units, which is referred to herein as the vertical current density. In this way, a current collector capable of achieving high current in both configurations would be similar to the prior art, and a current collector that can carry horizontal current when contacted at full width, but cannot carry similar vertical current in point contact would be an example of the invention described herein.

For example, it may be desirable for the current collector to be capable of carrying a horizontal current density of 0.1A/cm or 0.5A/cm, or 1A/cm or 2A/cm, or even 5A/cm. Whereas for a current collector that can carry the above-mentioned horizontal current densities, it is desirable not to carry 0.1A/mm²Or 0.5A/mm²Or 1A/mm²Or 2A/mm²Or even 5A/mm²The vertical current density of (1).

As mentioned above, tab welding is also commonly present in lithium ion battery cells to join internal components (particularly current collectors) together for connection to tab leads for transferring charge to an external source. In this case, it is crucial for very thin types of current collectors that such tab leads effectively contact the inner foil current collector and remain in place sufficiently to contact the external power source. Furthermore, because of the effectiveness described above and the unexpectedly superior thin film current collectors that allow for the desired operation of the battery cell itself, as well as the ability to provide internal fuse characteristics to prevent problems that may arise (dendrite formation, etc.), such tabs must not exhibit any degree of displacement or inhibit the failure of the same potentially uncontrolled charge. In other words, the effectiveness of the internal fuse result must not be overridden or compromised by tab issues. Surprisingly, it has been determined that this desired characteristic is permitted to be achieved by such a tab member.

Further, to that level, it is recognized that the film current collector actually allows the tabs to be effectively and securely welded thereto, and has the ability to actually allow both sides of the film to conduct electricity. The tab itself is actually thicker than each individual current collector, and when placed in contact with each other, the weld may be made to a depth that partially penetrates the tab material relative to the shape and depth of the weld itself. However, it has surprisingly been found that the weld may actually pass through the tab in a thin "flow" or similar manner, thereby allowing electrical conduction through such weld material to the tab. In this manner, a limited but effective conductive path is created, not only to allow the required conduction to the tabs (and then from the cell casing to an external source) at the weld location, but also to provide a means of limiting the actual amperage and temperature generated by such conduction current at each weld location. Such a result allows the aforementioned control of uncontrolled conduction from the metallized film current collector in the event of a short circuit (dendrite formation, etc.) because the charge will stop at the actual current collector surface and no other path for uncontrolled charge is provided. Thus, the welds may be provided at distances, e.g., up to five, evenly spaced from each other along the length of the tab member (extending along the current collector), thereby allowing effective electrical conductivity from the foil current collector to the tab for connection through the battery case to an external power source. Thus, the limited number of welds also reduces the number of potential runaway charge sites, although each shows limited amperage, in some cases multiples of this level show an increase. However, for high power or high current batteries, the number of welds per tab may be increased to accommodate the large amount of current required for efficient battery application. In this case, a greater number of welds may be required, and as many as 10 or 20, or even 50 welds per tab may be required. In the rare case of very high power or very high current batteries, it may even be necessary to perform more than 50 welds. In addition, the welding provides a base strength to prevent the tab from moving during use. Stability and stiffness are necessary to ensure proper operation of the cell as a whole. In this regard, limited welding does provide a level of reliability, and the addition of a draw tape (as applied to the current collector film) thereon also helps to prevent such potential problems.

Indeed, the thin film current collector has an unexpected benefit in preventing run away charge during short circuits. However, tab leads that require adequate contact with such current collectors in order to allow the battery cell to conduct electricity efficiently externally require a structural condition that allows such thin current collector films to utilize standard tab assemblies. As noted above, the ability to determine the appropriate dimensions of both the current collector membrane and the tabs for effective attachment and contact by suitable welding to pass current efficiently for cell operation while still exhibiting a suitably low runaway potential has proven difficult, particularly in view of the particular and acceptable thick monolithic current collector assembly in the state of the art. This unexpectedly effective result, particularly the tab contact and tensile strength characteristics as determined above, gives a complete lithium ion battery that can provide reduced weight or greater internal capacity for other components without sacrificing the power generation capability of the battery, while providing overall protection against charge runaway during a short circuit event.

Such lithium ion battery thin films may require certain unique processing steps due to their unique qualities. However, many processing steps well known in the art may also be employed. Generally, the method of making a lithium ion battery of the present membrane comprises the steps of:

a. providing an electrode having at least one metallized substrate having a coating of an ion storage material;

b. providing a counter electrode;

c. laminating the electrode and the counter electrode opposite to each other with a separator assembly interposed therebetween;

d. providing an encapsulation material comprising an electrical contact assembly, wherein the contact comprises a portion that is present inside the encapsulation material and a portion that is present outside the encapsulation material;

e. electrically connecting the electrical contacts to the metallized substrate;

f. introducing at least one liquid electrolyte with ions inside the encapsulating material; and

g. and sealing the packaging material.

The metallized substrate may be any substrate as described in the present disclosure.

As is well known in the art, the ion storage material may be, for example, a positive or negative electrode material of a lithium ion battery. The positive electrode material may include lithium cobalt oxide LiCoO₂Lithium iron phosphate LiFePO₄Lithium manganate LiMn₂O₄Lithium nickel manganese cobalt oxide LiNi_xMn_yCo_zO₂Lithium nickel cobalt aluminum oxide LiNi_xCO_yAl_zO₂Or mixtures of the above, or other materials known in the art. The negative electrode material may include graphite, lithium titanate Li₄Ti₅O₁₂Hard carbon, tin, silicon or mixtures thereof, or other materials known in the art. Additionally, the ion storage materials may include those used in other energy storage devices (e.g., supercapacitors). In such a supercapacitor, the ion storage material will comprise: activated carbon, activated carbon fibers, carbide-derived carbon, carbon aerogels, graphite, graphene, and carbon nanotubes.

The coating process may be any coating process generally known in the art. Doctor-over-roll and slot die are common coating processes for lithium ion batteries, but other processes (including electroless plating) may be used. In the coating process, the ion storage material is typically mixed with other materials, including binders such as polyvinylidene fluoride or carboxymethyl cellulose, or other film-forming polymers. Other additives to the mixture include carbon black and other conductive additives.

The counter electrode comprises a further electrode material having a different electrochemical potential than the ion storage material. Typically, if the ion storage material is a lithium ion negative electrode material, the counter electrode will be made of a lithium ion positive electrode material. In the case where the ion storage material is a lithium ion positive electrode material, the counter electrode may be a lithium ion negative electrode material. In the case where the ion storage material is a supercapacitor material, the counter electrode may be made of the supercapacitor material, or in some cases, may be made of a lithium ion negative electrode or a lithium ion positive electrode material. In each case, the counter electrode will comprise an ion storage material coated on a current collector material, which may be a metal foil or a metallized film as in the present invention.

In the lamination process, the electrode of the present invention is laminated with the counter electrode so that the electrode materials face each other with the porous separator therebetween. As is generally known in the art, electrodes may be coated on both sides, and the electrode stack formed by the electrode and counter electrode of the present invention alternates with a separator between each layer. Alternatively, strips of electrode material may be stacked as described above and then wound into a cylinder, as is also known in the art.

The potting material may include a rigid package such as a can for a cylindrical battery, a flat rigid casing, or a polymeric bag. In each case, there must be two mechanisms of electrical contact through the housing that are capable of holding different voltages and conducting current. In some cases, one portion of the housing itself forms one mechanism, while another portion is a different portion of the housing that is electrically isolated from the first portion. In other cases, the casing may be non-conductive, but allow two metal conductors to protrude through the casing, commonly referred to as tabs (tab).

Attaching the mechanism to make electrical contact with the metallized substrate can include conventional methods such as welding, tape bonding, clamping, stapling, riveting, or other mechanical means. Because the metal of the metallized substrate can be very thin, in order to achieve an interface that allows large currents to flow, face-to-face contact is typically required, resulting in a large surface area between the mechanism making electrical contact through the housing and the metallized substrate. To carry sufficient current, the surface area should be greater than 1 square millimeter (10)^-12Square meters), but may need to be greater than 3 square millimeters, even 5 square millimeters, or more preferably 10 square millimeters.

The liquid electrolyte is typically a combination/mixture of a polar solvent and a lithium salt. As mentioned above, commonly used polar solvents include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, but other polar solvents may be used, including ionic liquids or even water. Lithium salts commonly used in the industry include, but are not limited to: LiPF₆、LiPF₄、LiBF₄、LiClO₄And the like. The electrolyte may further containThere are additives known in the art. In many cases, the electrolyte may be flammable, wherein the safety features of the metallized substrate current collectors of the present invention advantageously prevent dangerous thermal runaway events that lead to ignition and damage to the battery and to the exterior of the battery.

Drawings

Fig. 1 is a prior art schematic of the structure of a wound cell (e.g., 18650 cell).

FIG. 2 is a prior art graphical representation of shrinkage as measured by dynamic mechanical analysis of several Lithium Ion Battery membranes as a function of temperature, as measured according to the NASA/TM-2010-216099 "Battery Separator Characterization and Evaluation procedure for NASA's Advanced Lithium Ion Batteries" section 3.5, which is incorporated herein by reference. Included are first generation separators (Celgard PP, Celgard trilayer), second generation separators (ceramic PE) and third generation separators (silver, gold, silver AR).

Fig. 3A is a prior art schematic of a Scanning Electron Micrograph (SEM) of a cross section of a pouch cell that has undergone a nail penetration test. These layers are aluminum and copper mapped by BEI (back scattered electron imaging). The nail is vertical on the left side. In each case, the aluminum layer has retracted from the nail, leaving a "skin" of aluminum oxide, the insulator.

FIG. 3B is an enlarged prior art schematic of one layer of the image shown in FIG. 3A. It shows a close-up image of the alumina layer and also reveals that the membrane has not shrunk at all and still separates the electrodes to the extreme edges.

Figure 4 is a schematic of the invention in which a thin layer of conductive material is on the outside and the central substrate is a layer that is thermally unstable at the temperatures required for thermal runaway. The substrate may be a melt layer, shrink layer, dissolution layer, oxidation layer, or other layer that is thermally unstable at temperatures between 100 ℃ and 500 ℃.

Fig. 5A is a prior art schematic of a thick aluminum current collector, typically between 12 and 20 microns.

Fig. 5B is a schematic of the present invention showing a 14 micron thick substrate with 1 micron of aluminum on each side. In the case of the current collector of the present invention, it is not able to carry the high currents associated with short circuits, whereas thick current technology is possible and does.

Fig. 6 and 6A show images of comparative examples 1-2, respectively, after being touched by the tip of a hot iron. The comparative example did not change after touching the hot iron.

Fig. 7, 7A and 7B show images of examples 1-3 after being touched by the tip of a hot iron, respectively. Examples 1-3 all show shrinkage as described in this disclosure for the substrate to be metallized.

Fig. 8, 8A and 8B show images of examples 4-6, respectively, after being touched by the tip of a hot iron. Example 4 shows the shrinkage as described in this disclosure for the substrate to be metallized. Example 5 has fibers that will dissolve in the lithium ion electrolyte upon heating. Example 6 is an example of a thermally stable substrate that requires a thin conductive layer to function as the present invention.

Fig. 9, 9A and 9B are SEM images of different magnifications of the cross-section, and one shows the metallized surface of one possible implementation of a current collector described in example 9. This metal is clearly much thinner than the original 20 micron thick substrate.

Fig. 10 and 10A are optical micrographs of comparative examples 3 and 4 after a short circuit showing ablation of the area around the short circuit but no holes.

Fig. 11 and 11A are optical micrographs of two regions of example 14 after shorting showing transparent pores in the material caused by the high current density of the short.

Fig. 12 shows a schematic diagram of the size and shape of the current collector used in the examples described below.

Fig. 13 illustrates a side perspective view of a single layer current collector with welded tabs as one potentially preferred embodiment.

Fig. 14 shows a side perspective view of a single layer current collector with tape bonded tabs as another potentially preferred embodiment.

Fig. 15 shows a side perspective view of a single layer current collector with staple stapled tabs as another possible preferred embodiment.

Fig. 16 illustrates, as another potentially preferred embodiment, a side perspective view of a single layer current collector having a single circular fold and a tape bonded tab.

Fig. 17 illustrates, as another potentially preferred embodiment, a side perspective view of a single layer current collector having a double circular fold and tape bonded tab.

Fig. 18 depicts, as another potentially preferred embodiment, a side perspective view of a single layer current collector with two parallel welded tabs.

Fig. 19 depicts, as another potentially preferred embodiment, a side perspective view of a single layer current collector with a single folded weld tab.

Fig. 20 shows a side perspective view of a single layer current collector with double rounded folded and welded tabs as another potentially preferred embodiment.

Fig. 21 illustrates a side perspective view of a plurality of single layer current collectors with double circular folds and welded tabs as another potentially preferred embodiment.

Fig. 22 shows a side perspective view of a plurality of single layer current collectors with a double circular fold and two opposing weld tabs as another potentially preferred embodiment.

Fig. 23 illustrates, as another potentially preferred embodiment, a side perspective view of a plurality of single layer current collectors in contact with a plurality of Z-folded clamped tabs.

Detailed Description

The following description and examples are merely representative of potential embodiments of the disclosure. The scope of the present disclosure and its scope in the following appended claims will be well understood by those of ordinary skill in the art.

As noted above, the present invention is a significant transformation and is contrary to all previous understanding and remedial measures performed within the lithium battery (and other energy storage device) industry. In contrast, the novel devices described herein provide a number of beneficial results and characteristics that have heretofore not been explored, let alone unexpected, in the field. Initially, although by way of comparison, it is important to note the significant differences involved between existing devices and those presently disclosed and broadly contemplated by the present invention.

Short circuit event embodiments

Comparative example 1

The positive electrode for lithium iron phosphate batteries was obtained from GB Systems, inc (GB Systems) in china. Aluminum tabs were 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 to a hot iron for 5 seconds and the temperature was measured to be 500 to 525 ° f using an infrared thermometer. There is no effect on the iron touching the current collector. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 6. Fig. 5 provides a representation of a conventional current collector within such a comparative cell.

Comparative example 2

Negative electrodes for lithium iron phosphate batteries were obtained from GB Systems, inc (china). Copper tabs were 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. Then, the copper foil was touched with a hot iron in the same manner as in comparative example 1. There is no effect on the iron touching the current collector. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 6. Fig. 5 provides a representation of the internal structure of such a battery, as in comparative example 1. The thickness of the current collector is important because it is a monolithic metal structure, rather than being thin as disclosed in the present invention.

Example 1

Polypropylene lithium battery separator materials were obtained from MTI Corporation (MTI Corporation). This material was manufactured by Celgard, product number 2500. The thickness, areal density and electrical resistance were measured and are shown in table 1 below. Then, the separator was touched with a hot iron in the same manner as in comparative example 1. The current collector was touched with a thermometer to create a small hole. The diameter was measured and contained in table 1. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 7.

Example 2

Ceramic coated polyethylene lithium battery separator materials were obtained from MTI Corporation (MTI Corporation). The thickness, areal density and electrical resistance were measured and are shown in table 1 below. Then, in the same manner as in example 1, the separator was touched with a hot iron. The current collector was touched with a soldering iron to create a small hole. The diameter was measured and contained in table 1. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 7A.

Example 3

Ceramic coated polypropylene lithium battery separator materials were obtained from MTI Corporation (MTI Corporation). The thickness, areal density and electrical resistance were measured and are shown in table 1 below. Then, in the same manner as in example 1, the separator was touched with a hot iron. The current collector was touched with a soldering iron to create a small hole. The diameter was measured and contained in table 1. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 7B.

Example 4

Aluminized biaxially oriented polyester film was obtained from All Foils, which was designed for helium filled party balloons. The aluminum coating can retain helium for a longer period of time, thereby providing a longer lasting lift (loft) for the balloon. The thickness, areal density and electrical resistance were measured and are shown in table 1 below. Then, the film was touched with a hot iron in the same manner as in example 1. The current collector was touched with a soldering iron to create a small hole. The diameter was measured and contained in table 1. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. A photograph was taken as shown in fig. 8. This material is 65% thinner, 85% lighter, and also dissipates the heat that would have the effect of interrupting internal shorts in an internally short lithium ion battery, as compared to the commercially available aluminum current collector in comparative example 1.

Example 5

Dreamweaver Silver 25, a commercially available lithium ion battery separator, was obtained. It is made from a blend of cellulose with polyacrylonitrile nanofibers and polyester microfibers in a papermaking process and calendered to a low thickness. Then, in the same manner as in example 1, the separator was touched with a hot iron. Touching the current collector with a thermometer did not create a hole. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. These materials have the following advantages compared to comparative examples 3-5 of the prior art: they do not melt or shrink in the presence of heat and therefore do not shrink back in an internally short-circuited lithium ion battery, thereby forming a larger internal short circuit. As shown in fig. 8A.

Example 6

Dreamweaver Gold 20, a commercially available prototype lithium ion battery separator, was obtained. It is made from a blend of cellulose with para-aramid nanofibers and polyester microfibers in a papermaking process and calendered to a low thickness. Then, in the same manner as in example 1, the separator was touched with a hot iron. Touching the current collector with a thermometer did not create a hole, as shown in fig. 8B. Thickness, areal density and electrical resistance were measured. The material was placed in an oven at 175 ℃ for 30 minutes and the shrinkage was measured. The advantages of this membrane compared to the prior art membrane are the same as in example 2.

TABLE 1

Comparative examples 1-2 are existing current collector materials that exhibit very low electrical resistance, high areal density and no reaction or any shrinkage at 175 ℃ exposed to hot iron tips.

Examples 1-3 are materials with infinite resistance, with low areal density, and melting under exposure to 175 ℃ or a hot iron tip. They are excellent substrates for metallization according to the invention.

Example 4 is an example of an aluminized polymer film that exhibits moderate electrical resistance, low areal density, and shrinks when exposed to 175 ℃ or hot iron tips. Which is an example of a potential positive current collector composite film according to the present invention. In practice, and as shown in further examples, it may be desirable to impart higher levels of metal coating to higher power batteries.

Examples 5-6 are materials with infinite electrical resistance, with low areal density but very low shrinkage when exposed to 175 ℃ or a hot iron tip. Metallized coatings are examples of the polymeric substrates of the present invention when their thickness is sufficiently thin that the metallized coating will degrade under high current conditions associated with short circuits. In addition, cellulose nanofibers and polyester microfibers will oxidize, shrink and ablate at temperatures well below the melting temperature of current practical metallic current collectors.

Example 5 is additionally made of polyacrylonitrile fibers, which swell when exposed to conventional lithium ion carbonate electrolytes, which is also an example of the polymer substrate of the present invention, such that swelling increases under heating and cracks are generated in the metallized coating that break the conductive paths, thereby improving the safety of the battery by eliminating or greatly reducing uniform conductive paths of the current collector under exposure to heat within the battery.

Example 7

The material used in example 5 was placed in the deposition position of the MBraun vacuum deposition system using an intermetallic crucible and aluminum pellets. Evacuating the chamber to 3X 10^-5Millibar. The power was increased until the aluminum melted and then set to a deposition rate of 3 angstroms/second. The deposition was carried out for 1 hour, and four samples were rotated on the deposition plate. This process was repeated 3 times, resulting in a total deposition time of 4 hours. The weight, thickness and resistance of the samples (DC and 1kHz, 1 inch strip measured between electrodes 1 inch apart) were measured and the results are shown in table 2 below. The dot resistance was also measured using a Hioki 3555Battery Hitester at 1kHz with 1 inch apart probe tips. The weight of aluminum added is calculated by dividing the weight added in the process by the area of the sample. This is divided by the density of the material to give the average thickness of the coating.

Example 8

20g/m were obtained by taking polyethylene terephthalate with a flat cross section and using a Tappi T206 process²Hand sheet (hand sheet) to prepare a nonwoven polymer substrate. These handsheets were then calendered at 10 meters per minute and 2000 pounds per inch using a 250 ° f hardened steel roll. This material was metallized according to the method of example 7 and the same measurements were made and recorded in table 2.

Example 9

The material according to example 5 was deposited according to the method of example 7, except that the coating was carried out at a set rate of 5 a/s for 60 minutes. The sample was inverted and coated on the back side in the same procedure. The surfaces and cross-sections of these materials were imaged under a Scanning Electron Microscope (SEM), and the images are shown in fig. 9, 9A, and 9B.

Example 10

The material was prepared according to the procedure of example 9, except that the deposition on each side was only 20 minutes.

Example 11

The polymer substrate of example 8 was prepared except that the sheet was not calendered. Aluminum deposition at a deposition rate of 5 angstroms/second on each side for 20 minutes. Because the material is not calendered, the porosity is very high, resulting in very high electrical resistance values and thin coating weights. Comparison of example 11 with example 8 shows the benefits of calendering, which are unexpectedly high.

TABLE 2

Sample (I)	Increased weight	DC resistance	1kHz resistor	1kHz point resistance	Average coating thickness
						Unit of	g/m²	Ohm/□	Ohm/□	Ω	Micron meter
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

The aluminum coated polymer substrate from example 9 was coated with a mixture of 97% NCM positive electrode material (NCM523, available from BASF corporation) in a solution of N-methyl-2-pyrrolidone, 1% carbon black, and 2% PVDF binder. At a thickness of 71 microns, the coating weight was 12.7mg/cm². The material was cut to fit 2032 coin cells and mated to a graphite negative electrode (6 mg/cm) coated on a copper foil current collector²96.75% graphite (BTR), 0.75% carbon black, 1.5% SBR, and 1% CMC). Single layer coin cells were prepared by placing the negative electrode, separator (Celgard 2320) and NCM coating material into the cell, charging with electrolyte (60 μ L, 1.0M LiPF6 in EC: DEC: DMC 4:4:2vol +2 w.% VC) and sealing the cell by crimping the casing. To obtain sufficient conductivity, a portion of the aluminum-coated polymer substrate from example 9 was left uncoated with positive electrode material and folded to contact the housing of the button cell, completing the conductive path. The battery was formed by charging to 4.2V at a constant current of 0.18mA, and then charging at a constant voltage (4.2V) until the current dropped to 0.04 mA. The cell was cycled between 4.2V and 3.0V three times at a current of 0.37mA and an average discharge capacity of 1.2mAh was obtained.

Example 13

A battery was made according to this procedure and using the material of example 12, except that the separator used was Dreamweaver Silver 20. The battery was formed by charging to 4.2V at a constant current of 0.18mA, and then charging at a constant voltage (4.2V) until the current dropped to 0.04 mA. The cell was cycled between 4.2V and 3.0V three times at a current of 0.37mA and an average discharge capacity of 0.8mAh was obtained. Thus, in this and the previous examples, the rechargeable lithium ion cell in operation was made to an aluminum thickness of less than 1 micron.

Comparative example 3

The aluminum tab of comparative example 1 (about 2cm x 4cm) was connected to the ground of the current source by a metal connector that contacted the entire width of the sample. The voltage limit was set to 4.0V and the current limit was set to 1.0A. A high voltage probe connected to a current source was first touched to a metal connector that contacted the entire width of the sample, then touched the aluminum tab multiple times, creating a short circuit at 1.0A. The tip of the probe has about 0.25mm²The area of (a). When contact is made along the entire width, current flows normally. When the probe first touches the tab, a spark is generated, indicating a very high initial current density. The resulting defects in the current collector sometimes only cause pores, while ablation occurs at other times, but the current collector remains intact. In all cases, the circuit remains a short circuit with 1.0A flow. The micrograph was taken of a non-porous ablation defect and is shown in figure 10. The current source limits were set at 5.0, 3.0, 0.6A, 0.3A and 0.1A, the experiment was repeated and in all cases the dimensions were about 0.25mm when contacting along the entire width of the current collector and when using a tip size²The result is a continuous current below the test current limit for the point probe of (1).

Comparative example 4

The copper tab of comparative example 2 of similar size was tested in the same manner as comparative example 3. When contact is made along the entire width, current flows normally. When the probe first touches the tab, a spark is generated, indicating a very high initial current density. The resulting defects in the current collector sometimes only result in pores, while othersAblation may occur, but the current collector remains intact. In all cases, the circuit remains a short circuit with 0.8A flow. A photomicrograph was taken of a non-porous ablation defect and is shown in fig. 10A. The current source limits were set at 5.0, 3.0, 0.6A, 0.3A and 0.1A, the experiment was repeated and in all cases the dimensions were about 0.25mm when contacting along the entire width of the current collector and when using a tip size²The result is a continuous current below the test current limit for the point probe of (1).

Example 14

The aluminum coated polymeric substrate material of the present invention of example 7 having similar dimensions was tested using the same method as comparative examples 3-4. When contact is made along the entire width, current flows normally. In each case where the probe directly touches the current collector of the invention, much less spark is generated and the current stops flowing after the initial spark, leaving an open circuit. In all cases, the final defect is a hole. Photomicrographs of several examples of wells are shown in fig. 11 and 11A. The current source limits were set to 5.0, 3.0, 0.6A, 0.3A and 0.1A, the experiment was repeated and in all cases the result was a continuous flow of current when contact was made along the entire width of the current collector; and no current flows through the inventive examples when the probe is in direct contact with the inventive examples of collectors.

The key invention shown is that when short circuits are experienced as in comparative examples 3-4 and example 14, the result is a sustained short circuit for the prior art; the result of using the material of the present invention is an open circuit without continuous current flow (i.e., no significant current movement). Thus, the short circuit of the prior art can and does generate heat, which can melt the separator, dissolve the SEI layer and cause thermal runaway of the battery. The open circuit of the current collector of the present invention will not generate heat, thus providing a battery capable of carrying internal short circuits without causing thermal runaway and the resulting smoke, heat and flame.

Examples 15 and 16 and comparative examples 5 and 6

In a roll-to-roll process, on 10 micron polyethylene terephthalate filmTwo metallized films are made. In this process, a roll of film is placed in a vacuum metallization production machine (an example of which is Top Met 4450 available from Applied Materials), and the chamber is then evacuated to a low pressure. The roll is passed through a heated boat containing molten aluminum at a high speed of, for example, 50 m/min. Above a heated boat containing molten aluminum is a mass of aluminum soot that is deposited on the film and the deposition rate is controlled by the speed and aluminum temperature. A roll of about 500m long and 70cm wide was made by a multi-pass process until the aluminum coating was about 300 nm. The coating process was repeated to coat the other side of the film, and the resulting product was used herein as example 15 (the current collector of the invention of fig. 4 is a representation of the current collector used in this example). Thus, example 16 was produced in the same manner except that the metal in the boat was copper (and the schematic diagram of fig. 5B represents the current collector used in the structure of the present invention). The basis weight, thickness and conductivity of each film were measured and recorded in table 3 below. Basis weight of 13.8g/m by subtracting 10 micron polyethylene terephthalate film²The coating weight was calculated. By dividing the coating weight by the density of the material (2.7 g/cm for aluminum)³Copper 8.96g/cm³) And assuming equal on both sides, the "calculated coating thickness" is calculated.

Comparative example 5 is a commercial 17 micron thick aluminum foil. Comparative example 6 is a commercial 50 μm thick copper foil. Comparative example 7 is a commercially available copper foil 9 μm thick.

TABLE 3

Sample (I)	Basis weight	Coating weight	Thickness of	DC resistance	Calculated coating thickness
						Unit of	g/m²	g/m²	Micron meter	Ω	Micron meter
Example 15	17	3	11	0.081	0.5
						Example 16	24	10	11	0.041	0.5
Comparative example 5	46		17
						Comparative example 6	448		50
Comparative example 7	81		9

Example 15, example 16, comparative example 5 and comparative example 6 were further tested to test their ability to carry very high current densities. A test apparatus was prepared that would bring a polished copper wire with a radius of 0.51mm (24AWG gauge) into contact with the current collector film or foil. The film or foil under test is grounded with an aluminum contact that is held in contact with the film or foil under test and has a contact area greater than 1 square centimeter. The probe was connected in series with a high power 400W resistor of 0.335 ohms and connected to a Volteq HY3050EX power supply set to control current. The current collector to be measured is placed in a setup (setup) with the polished wire in contact with the current collector surface at zero input current. The current was increased in 0.2 amp increments and held for 30 seconds each increment while the voltage across the resistor was measured. When the voltage drops to zero (indicating that no more current is flowing), a fault is indicated in the sample. Example 15, example 16, comparative example 5 and comparative example 6 were each tested. Example 15 failed at 7A (the average of two measurements). Example 16 failed at 10.2A (the average of two measurements). Comparative example 5 and comparative example 6 both failed below 20A. Both example 15 and example 16 showed pores in the current collector with a radius of more than 1mm, while neither comparative example 5 or 6 showed any damage to the foil. In this example test, it is advantageous to have a current collector that cannot carry a current greater than 20A, or preferably greater than 15A, or more preferably greater than 12A.

In another test intended to simulate the use of these inventive current collectors as tabs for connecting the electrode stack of a cell to an electronic device in use (either internal or external to the cell), examples 15 and 16 and comparative examples 5 and 6 were tested for current capacity along the strip. To prepare the samples for testing, the current collector was cut into the shape shown in fig. 12, consisting of a strip of material 4cm × 1cm (4cm × 1cm), the ends of which end in truncated right-angled isosceles triangles with sides of 4 cm. Each triangle of the test piece was contacted by an aluminum part having a contact surface area of greater than 1 cm. One side was connected through a 400W 0.335 ohm resistor and the circuit was connected to a Volteq HY3050EX power supply. The voltage is measured along the resistor to measure the current and the part shows a fault when the voltage drops to zero. For each test, the part was connected to a power supply set to zero current, then increased in 0.2A increments and left at each new voltage for 30 seconds until the sample failed and the current dropped to zero. The test is configured such that the metallized current collector can be measured with one or both sides of the metallized current collector in contact. The fault currents are shown in table 4 below. For materials tested in 4cm x 1cm strips, it is advantageous to provide internal fuses by limiting the amount of current that can flow to less than 20A, or preferably less than 15A, or more preferably less than 10A, respectively, each with single or double sided contact.

TABLE 4

Sample (I)	Single side fault voltage	Single side fault voltage
			Unit of	V	V
Example 15	2.7	4.5
			Example 16	24	10
Comparative example 5	No failure below 20A	No failure below 20A
			Comparative example 6	No failure below 20A	No failure below 20A

Examples 17 to 19 and comparative example 8

Batteries were fabricated by coating the standard foil current collectors and metallized PET film current collectors from examples 15 and 16 with electrode material. NMC523 positive electrode material was prepared using BASF NMC523 (97%), carbon black (2%) and PVDF (1%) in NMP solvent, coated on an aluminum current collector (15 micron aluminum current collector), example 15 at 220g/m²Basis weight (corresponding to 3.3 mAh/cm)²Positive electrode loading density). The anode material was prepared using graphite BTR-918S (94%), carbon black (5%) and PVDF (1%) in NMP solvent, and was at 118g/m²Velocity (corresponding to 4.0 mAh/cm)²Negative loading density) was coated on a copper current collector (18 micron copper current collector). Four double-sided anodes were prepared, as well as three double-sided cathodes and two single-sided cathodes. They were stacked with Celgard 2500 separatorTogether to form a small pouch cell, which is then filled with electrolyte and sealed at a design capacity of 1 Ah. Four types of cells were made with different combinations of foil materials and the capacities were measured at C/10 and C/5 (i.e., 0.1A and 0.2A). The battery was formed by charging to 4.2V at 100mA and was held at 4.2V 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 5

Thus, it has been shown that the examples provided above show desirable thickness, metal coating and conductivity results needed to prevent thermal runaway within an electrolyte-containing cell, providing not only a safer and more reliable type, but also a type that requires far fewer internal weight components than ever without sacrificing safety (but in fact is an improvement in this regard).

As noted above, it is within the present invention to have the ability to provide such thin current collectors (as internal fuses within lithium battery articles), but also to have the necessary benefits of having a tab structure that ensures the generated voltage is transferred to the outside of the target cell. In addition, the ability to further take advantage of the beneficial thin structure of the current collector described above lends itself to any number of myriad configurations within the target battery article itself, potentially resulting in a cumulative power level all with beneficial internal fuse components. These are discussed in more detail in fig. 12-22.

Fig. 13 shows a single thin film current tab/current collector 600 having a metallized film layer 614 and a lower non-metallic layer 616. An electrically conductive tab 610 (leading to the external power transfer component of the cell) is also provided, vertically aligned with the current collector, and connected to the current collector by a weld 612.

Fig. 14 shows a similar current collector 620, but with tab 622 having adhesive tape 624 connecting tab 622 to current collector 634 for such conductive purposes. As described above, the tab/collector 620 has the metallized film layer 626 and the lower non-metal layer 632. The tape member 622 is disposed on the outer surface 628 of the tab and opens into the non-metallic layer 626 of the current collector, which provides a shear strength adhesive quality to hold the tab in place and for conductive purposes in a suitable manner.

Fig. 15 provides a different tab/current collector 640 showing a different way of connecting a tab 642 to a single thin current collector 648 (having a metallized film layer 644 and a lower non-metallic layer 650) by connecting the two components with a conductive staple component 646.

Such a flat current collector structure allows for a typical cell structure (e.g., as shown in fig. 1) having a compact cell structure. Fig. 16 shows a single fold 710 of a tab/current collector 700, the current collector 700 having a single tape bonded tab 702 attached to a metallized film surface 712 (which covers a non-metallic layer 708, as described above). In this manner, the single fold 710 current collector 704 imparts the ability to increase the amount of power generation within the cell, despite the need to slightly increase the cell size from a flat configuration.

Fig. 17 shows a tab/collector 720 that is double folded 732 using the same thin structure current collector 724. Thus, this double fold 732 further provides the ability to connect the two

sides

726, 728 of the current collector 724 that might otherwise be electrically insulated by a polymer film located between the two conductive layers. Tab 722 is attached at the current collector surface 730 for electrical conductivity purposes of this double fold 732.

Fig. 18 also includes a flat tab/collector 750 having the same type of upper 758 and lower 762 surfaces. In this case, the

tabs

752, 754 are provided as two parallel structures that contact both the upper surface 758 and the lower surface 760 of the current collector 762.

Such tabs

752, 754 include welds 756 for attachment to the two

surfaces

758, 758 and attachment to the two

surfaces

758, 758.

Fig. 19 shows a structure 780 similar to fig. 16, but with a single folded tab 794 in a position where the single folded tab 794 is in contact with both

surfaces

788, 790 of the current collector 792 by a weld 786 and where the two extended prongs (prong)782, 784 of the folded tab 794 exit therefrom.

Fig. 20 shows a welded 804 tab 802 welded to a doubly folded 810 tab/current collector 800, thus exhibiting the same ability to join electrically insulating

layers

808, 812 as part of the current collector 806 as described above, but with a safer weld 804 in the following locations, thus being more reliable and potentially more efficient for power transmission.

Fig. 21 thus shows a composite tab/multiple current collector structure 820 with multiple (here five) such double circular folded 856

current collectors

826, 828, 830, 832, 834 having metallized film layers 858, 860, 862, 864, 866 and lower

non-metal layers

846, 848, 850, 852, 854 connected in series for greater capability to connect even electrical insulation layers, thereby achieving electrical conductivity through a single tab 822 connected with a top double circular folded current collector 826 with a weld 824 for electrical conductivity. The weld tabs 822 are also held firmly in place for reliability purposes.

In fig. 22, the tab 904 of the opposing second weld 906 is provided, which also has such a plurality of

current collector arrays

908, 910, 912, 914, 916 of circular folds 938. Such a tab/current collector structure 900 allows for increased power generation without the need to increase the volumetric weight of the subject battery cell by configuring and connecting two

tabs

902, 904 with two external

current collectors

908, 916, as previously described. As described above, the metallized film layers 940, 942, 944, 946, 948 are provided with opposing

non-metallic layers

928, 930, 932, 934, 936, which are present as other such current collector examples.

Referring to fig. 23, a tab/current collector structure 960 as yet another non-limiting example clamps tabs 962 of a plurality of Z-folds 972 to a series of parallel flat thin

current collectors

964, 966, 968, 970 (here four) (as described above), metallic layers with metallized film layers 974, 978, 982, 986 and lower

non-metallic layers

976, 980, 982, 984, again providing a series of different ways to generate cumulative power despite having flat thin

current collectors

964, 966, 968, 970 (acting as a plurality of internal fuses).

This configuration of fig. 13 and 22 thus allows for different external connections to be made to the internal fuse components of the vertical lithium battery.

Having described the invention in detail, it will be apparent that variations and modifications thereof can be made by those skilled in the art without departing from the scope of the invention. The scope of the invention should, therefore, be determined only by the following claims.

Claims

1. An energy storage device comprising an anode, a cathode, at least one separator between the anode and the cathode, an electrolyte, at least one thin film current collector in contact with at least one of the anode and the cathode, and at least one tab attached to the at least one thin film current collector, wherein

a. The tab is attached to the current collector by a connection device;

b. said connection means exhibiting electrical contact with the exposed surface of said tab and said thin film current collector;

c. the negative electrode or the positive electrode is interposed between at least a portion of the thin film current collector and the separator;

d. the current collector comprises a conductive material coated on a non-conductive material substrate;

e. under the working voltage of the energy storage device, the current collector stops conducting electricity at the contact point of the short circuit; and

f. the voltage is at least 2.0 volts.

2. The energy storage device of claim 1, wherein the connection means is selected from the group consisting of a weld, an adhesive tape, a staple, a plunge metal strip, a z-fold metal strip, a conductive adhesive, and a clamp.

3. The energy storage device of claim 2, wherein the connection means consists of 2-50 connectors distributed throughout the current collector to allow uniform current flow from electrode material to the tabs, respectively.

4. The energy storage device of claim 1, wherein the current collector is folded to allow face-to-face contact between opposing sides of the current collector.

5. The energy storage device of claim 1, wherein the membrane is a polymer, a non-woven fabric, a textile, or a ceramic.

6. The energy storage device of claim 1, wherein the substrate of non-conductive material is a polymer film.

7. The energy storage device of claim 1, wherein the electrolyte is a combustible organic electrolyte.

8. The energy storage device of claim 1, wherein the tabs are a first tab in contact with an upper surface of the current collector and a second tab in contact with a lower surface of the current collector, the first tab and the second tab being parallel.

9. The energy storage device of claim 1, wherein the tab is folded over the current collector such that the first prong of the tab is in contact with an upper surface of the current collector and the second prong of the tab is in contact with a lower surface of the current collector, the first and second prongs being parallel.

10. The energy storage device of claim 1, wherein the current collector has a double-folded configuration to create two electrically insulating layers.

11. The energy storage device of claim 10, wherein the current collector is a plurality of current collectors connected in series, wherein the tab is attached to a last current collector of the plurality of current collectors.

12. The energy storage device of claim 11, further comprising a second tab attached to a first current collector of the plurality of current collectors, the tab and the second tab being parallel.

13. An energy storage system, comprising:

a negative electrode;

a positive electrode;

at least one separator between the negative electrode and the positive electrode;

an electrolyte;

at least one thin film current collector in contact with at least one of the negative electrode and the positive electrode, the current collector comprising a conductive material coated on a non-conductive material substrate, the current collector ceasing to conduct at a short-circuited contact point at an operating voltage of the energy storage system, the voltage being at least 2.0 volts;

at least one tab attached to the at least one thin film current collector; and

a connection device configured to attach the tab to the current collector, the connection device exhibiting electrical contact with the exposed surface of the tab and the thin film current collector;

wherein the negative electrode or the positive electrode is interposed between at least a portion of the thin film current collector and the separator.

14. The energy-storage system of claim 13, wherein the connection means is selected from the group consisting of a weld, an adhesive tape, a staple, a plunge metal strip, a z-fold metal strip, a conductive adhesive, and a clamp.

15. The energy storage system of claim 14, wherein the connection means consists of 2-50 connectors distributed across the current collector to allow uniform current flow from the electrode material to the tabs, respectively.

16. The energy storage system of claim 13, wherein the current collector is folded to allow face-to-face contact between opposing sides of the current collector.

17. The energy storage system of claim 13, wherein the membrane is a polymer, a non-woven fabric, a textile, or a ceramic.

18. The energy storage system of claim 13, wherein the substrate of non-conductive material is a polymer film.

19. The energy storage system of claim 13, wherein the electrolyte is a combustible organic electrolyte.

20. The energy storage device of claim 13, wherein the tabs are a first tab in contact with an upper surface of the current collector and a second tab in contact with a lower surface of the current collector, the first tab and the second tab being parallel.

21. The energy storage device of claim 13, wherein the tab is folded over the current collector such that the first prong of the tab is in contact with an upper surface of the current collector and the second prong of the tab is in contact with a lower surface of the current collector, the first and second prongs being parallel.

22. The energy storage device of claim 13, wherein the current collector has a double-folded configuration to create two electrically insulating layers.

23. The energy storage device of claim 22, wherein the current collector is a plurality of current collectors connected in series, wherein the tab is attached to a last current collector of the plurality of current collectors.

24. The energy storage device of claim 23, further comprising a second tab attached to a first current collector of the plurality of current collectors, the tab and the second tab being parallel.