Electrochemical energy storage devices

Abstract

To provide an ultra-thin electrochemical energy storage device which utilizes electrode material with multi-layer current collectors and with an organic electrolyte between the electrodes.SOLUTION: Multiple cells may be positioned in a plurality of stacks, and all of the cells may be connected in series, parallel or some combination thereof. The energy storage device can be constructed with a thickness less than 0.5 millimeter and exhibit very low ESR and relatively high temperature range capabilities.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] Claiming priority This application claims the benefit of a previously filed U.S. provisional patent application entitled "ORGANIC ELECTROLYTE CAPACITORS," assigned U.S. patent application Ser. No. 62 / 018,739, filed Jun. 30, 2014, and incorporated herein by reference for all purposes.

[0002] The presently disclosed technology relates generally to electrochemical systems and corresponding methodologies for the storage and release of electrical energy. More particularly, the presently disclosed technology relates to the construction of organic-based electrolytic capacitor devices having extremely low equivalent series resistance (ESR) (and corresponding low resistivity) and enhanced temperature operational capability, along with ultra-thin construction, to provide specialized supercapacitor energy storage device performance. [Background technology]

[0003] The presently disclosed subject matter generally relates to electrochemical energy storage devices and methods of manufacture. In particular, the presently disclosed subject matter relates to electrochemical systems for use in electronic circuits, such as as capacitors and / or batteries. More particularly, the presently disclosed subject matter relates to electrochemical systems having organic solution electrolyte materials.

[0004] Additionally, in part, the subject matter disclosed herein relates to improved designs for the assembly of multiple single cells of an electrochemical system. More specifically, the individual cells can be individually connected together to form a stack (in a single case or multiple cases), and the stacks are connected together to form the assembly. Additionally, the subject matter disclosed herein is more versatile for implementing cell-to-cell or stack-to-stack connections in series, parallel, or combinations thereof, and for implementing hybrid packs of one or more batteries combined with one or more capacitors in a single integrated product.

[0005] As various electronic devices become more portable and offer more functionality, corresponding advances are required in the features and components of such devices that enable such portability. Often, a limiting factor in both the size and functionality of an electronic device is the size and weight of its component parts, particularly the size and weight of the associated energy storage components. The drive toward miniaturization of electronic devices in general has also resulted in the integration of various components into a single device to conserve both space and weight.

[0006] Typical primary energy sources used in portable electronic devices include electrochemical batteries and / or electrochemical capacitors. As with other devices and components, one limiting aspect of energy storage components is the packaging of the electrochemical system and the resulting system size.

[0007] From a performance standpoint, additional aspects that may affect or limit the use of a particular structure in a particular application are the temperature range within which the component will function, as well as the equivalent series resistance (ESR) of the component with respect to the associated circuitry.

[0008] It is therefore desirable to provide ultra-thin (very low height) energy storage components that can comprise electrochemical capacitors that use organic electrolytes.

[0009] It would also be desirable to provide such electrochemical energy storage components useful in a single electronic device, where the cells are in series or parallel, or a combination thereof, depending on the construction of the component.

[0010] It would further be desirable to provide such devices that have improved extremely low ESR (and corresponding extremely low resistivity) and that have an extended temperature range for useful operation.

[0011] Various implementations of capacitor devices and associated assemblies, as well as construction methodologies therefor, have been developed, but no design has emerged that generally embodies all of the desired features as set forth below in accordance with the subject technology. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 6,576,365 Summary of the Invention

[0013] The presently disclosed subject matter recognizes and addresses various of the aforementioned limitations and shortcomings and others related to both the design of electrochemical energy storage components and the methods of making the same. Accordingly, generally, it is an object of certain embodiments of the presently disclosed technology to provide improved designs for certain capacitor components and component assemblies associated with organic electrolyte-based capacitors. Other objects generally relate to providing improved ultra-thin electrochemical energy storage components connected in series, parallel, or some combination thereof, as well as improved methods of making such components.

[0014] SUMMARY OF THE DISCLOSURE Accordingly, it is a principal object of the presently disclosed subject matter to provide an improved electrochemical capacitor.

[0015] Another more specific object of the presently disclosed subject matter is to provide an electrochemical capacitor device having a very low (or ultra-low) equivalent series resistance (ESR) (and correspondingly very low resistivity).

[0016] Moreover, it is a further object of the presently disclosed subject matter to provide an ultra-thin electrochemical capacitor device. In this context, it is a more specific object of the presently disclosed subject matter to provide an electrochemical energy storage component whose structure facilitates the arrangement of multiple connected cells in series, parallel, or a combination thereof to vary capacitance and / or voltage.

[0017] It is a further object of the presently disclosed subject matter to provide ultra-thin electrochemical energy storage components that can be efficiently manufactured.

[0018] It is a further object of the presently disclosed subject matter to provide electrochemical energy storage components that effectively have an extended temperature range of operation.

[0019] It is a further object of the presently disclosed subject matter to provide improved electrochemical energy storage components that may be effectively manufactured with significantly reduced exposure to moisture during the manufacturing process, yielding products with improved dimensional stability sensitive to thermal exposure.

[0020] It is a further object of the presently disclosed subject matter to provide electrochemical energy storage components that effectively comprise low ESR pulsed supercapacitors, or improved low ESR electrochemical double layer capacitors (EDLCs).

[0021] One exemplary embodiment according to the presently disclosed subject matter relates to an ultra-thin electrochemical energy storage device. Such a device preferably comprises a pair of respective internal electrodes with an electrolyte, a separator layer between each of such electrodes, a pair of respective current collectors, each one of such current collectors being on the exterior of each of such electrodes, and a case surrounding the current collectors and having a respective pair of terminals connected to each of such current collectors. Preferably, the contents of such a case also have a minimum thickness of less than 0.5 millimeters.

[0022] In some variations of the foregoing, such cases can have a water content of about 10 ppm or less. In some such alternatives, such electrolytes can comprise organic electrolytes, and in others, such electrolytes comprise, at least in part, propylene carbonate.

[0023] In other alternative embodiments, such cases can have a moisture content of about 10 ppm or less, and such devices can have a resistivity of about 1.5 Ω·cm2 or less per electrode area, and a temperature operational range rating of -40° to 70° C.

[0024] In yet other configurations of the exemplary embodiment, multiple such devices may be arranged as multiple cells positioned within multiple stacks configured in either series or parallel connections, or a combination thereof.

[0025] In yet another alternative configuration of the exemplary embodiment, such a device can include a plurality of such pairs of internal electrodes, separator layers, and such pairs of current collectors surrounded by such a case, and such a case can have a thickness of 0.5 millimeters to 5.0 millimeters.

[0026] In other embodiments of the exemplary ultra-thin electrochemical energy storage devices disclosed herein, the electrolyte can comprise an organic electrolyte; the device can comprise an electrochemical double-layer (ECDL) capacitor having a capacitance density of at least about 10 Farads per cc of active electrode volume. In yet another alternative embodiment of the ultra-thin electrochemical energy storage devices disclosed herein, the electrolyte can have a boiling point greater than 200° C.; the case can further include a thermally stable sealing material; and the capacitor can have a temperature operational half-voltage range rating of up to 90° C. Alternatively, the The organic electrolyte can include at least some propylene carbonate; such a case can have dimensions of approximately 50 mm length by 40 mm width by 0.5 mm thickness and can maintain dimensional stability at storage temperatures up to about 105° C. while also maintaining an extremely low ESR of at least about 150 mΩ.

[0027] In yet another exemplary embodiment disclosed herein, an ultra-thin, ultra-low ESR supercapacitor preferably comprises a pair of respective internal electrodes with an organic electrolyte, an ultra-thin separator layer between each of such electrodes, a pair of respective multi-layer current collectors, each one of such current collectors being outside each of such electrodes, and a case enclosing the current collectors and having a respective pair of terminals connected to each of such current collectors, the contents of such case preferably having a minimum thickness of less than 0.5 millimeters and a water content of about 10 ppm or less, such supercapacitor having a resistivity of about 1.5 Ω cm2 or less for the electrode area, a capacitance density of at least about 10 Farads per cc of active electrode volume, and a temperature operating range rating of -40° to 70° C.

[0028] In an exemplary variation of such a supercapacitor disclosed herein, such a supercapacitor may comprise a carbon-carbon double layer capacitor having a voltage rating of 4.2 volts and a half voltage range rating over a temperature operating range of −40° to 90° C. In another embodiment, such an organic electrolyte may include at least some of propylene carbonate.

[0029] In other alternatives, such supercapacitors may be arranged as cells positioned in stacks, in some such examples, such stacks of cells may be arranged in either series or parallel connections, or a combination thereof.

[0030] In other embodiments of such exemplary supercapacitors, such devices can include multiple such pairs of internal electrodes, separator layers, and such pairs of current collectors surrounded by such a case, and such a case can have a thickness of 0.5 millimeters to 5.0 millimeters.

[0031] In yet other variations of exemplary embodiments of the presently disclosed supercapacitors, the electrolyte can have a boiling point above 200° C.; the case can further include a thermally stable sealing material; and the supercapacitor can have a half-voltage range rating over an operating temperature of up to 90° C. In others, the case can have dimensions of approximately 50 mm length by 40 mm width by 0.5 mm thickness, and can maintain dimensional stability at storage temperatures up to about 105° C. while also maintaining an extremely low ESR of at least about 150 mΩ.

[0032] From the full disclosure herein, it should be understood that the subject matter disclosed herein equally relates to the device, as well as the corresponding and / or associated methodology. One exemplary embodiment of the methodology disclosed herein relates to a methodology for manufacturing an ultra-thin electrochemical energy storage device, which preferably includes the steps of providing a pair of respective internal electrodes with an electrolyte, together with a separator layer between each of the electrodes, providing a pair of respective current collectors, each one of the current collectors being on the outside of each of the electrodes, and surrounding the current collectors by a case having a respective pair of terminals connected to the current collectors, respectively. Moreover, preferably according to such exemplary embodiment, the contents of the case have a minimum thickness of less than 0.5 millimeters. In some variations of such methodology, such methodology may be carried out in a controlled environment having a water content of about 10 ppm or less.

[0033] In other variations disclosed herein, a plurality of such devices may be arranged as a plurality of cells positioned in a plurality of stacks configured in either series or parallel connections, or combinations thereof, to selectively achieve a desired capacitance and / or operational voltage level. In yet other variations, such devices may include a plurality of such pairs of internal electrodes, separator layers, and such pairs of current collectors surrounded by such a case, which may have a thickness of 0.5 millimeters to 5.0 millimeters.

[0034] In another exemplary alternative, such electrolyte can include at least some propylene carbonate; such a case can have dimensions of approximately 50 mm length by 40 mm width by 0.5 mm thickness and can maintain dimensional stability at storage temperatures up to about 105° C. while also maintaining an extremely low ESR of at least about 150 mΩ.

[0035] Another exemplary embodiment disclosed herein relates to a methodology for making an ultra-thin, ultra-low ESR supercapacitor, the methodology preferably including the steps of providing a pair of respective internal electrodes with an organic electrolyte with an ultra-thin separator layer between the respective electrodes, providing a pair of respective multi-layer current collectors, each one of the current collectors being outside of each of the electrodes, and surrounding the current collectors with a case having a respective pair of terminals connected to the current collectors. Further, according to such exemplary embodiment, the contents of the case preferably can have a minimum thickness of less than 0.5 millimeters, the methodology is carried out in a controlled environment having a water content of about 10 ppm or less, and the supercapacitor has a resistivity of about 1.5 Ω·cm2 or less for the electrode area, a capacitance density of at least about 10 Farads per cc of active electrode volume, and a temperature operating range rating of -40° to 70° C.

[0036] In some variations of the foregoing, such methodologies may include arranging a plurality of such supercapacitors as a plurality of cells positioned in a plurality of stacks to selectively achieve a desired capacitance and / or operational voltage level. In other such variations, such stacks of a plurality of cells may be arranged in either series or parallel connections, or a combination thereof, to achieve a hybrid pack of one or more batteries combined with one or more capacitors in a single integrated product. In yet other variations, such devices may include a plurality of such pairs of internal electrodes, separator layers, and such pairs of current collectors surrounded by such a case, which may have a thickness of 0.5 millimeters to 5.0 millimeters.

[0037] In other alternative embodiments disclosed herein, the electrolyte can have a boiling point greater than 200°C; the case can further include a thermally stable sealing material; and the supercapacitor can have a half-voltage range rating over an operating temperature of up to 90°C.

[0038] Additional objects and advantages of the presently disclosed subject matter will be set forth herein or will become apparent to those skilled in the art from the following detailed description. It should also be further understood by reference to this specification that modifications and variations to the features and materials specifically shown and discussed herein may be made in the various embodiments and uses of the presently disclosed subject matter without departing from the spirit and scope of the present specification. Such variations may include, but are not limited to, the substitution of equivalent steps, means, features and materials from those shown or discussed, as well as the functional or positional reversal of various steps, parts, features, etc.

[0039] Moreover, it will be understood that different embodiments of the subject matter disclosed herein, as well as different preferred embodiments herein, can include various combinations or configurations of the steps, features, elements, or equivalents thereof disclosed herein (including combinations of steps, features, or configurations thereof that are not explicitly shown in the figures or described in the detailed description).

[0040] These and other features, aspects and advantages of the presently disclosed subject matter will become better understood with reference to the following description: The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the presently disclosed subject matter and, together with the description, serve to explain the principles of the presently disclosed subject matter.

[0041] A full and enabling description of the subject matter disclosed herein, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in this specification, which makes reference to the accompanying figures. [Brief description of the drawings]

[0042] [Figure 1] FIG. 1 is an exploded isometric view of layers comprising an exemplary prior art electrochemical energy storage device. [Diagram 2] 1 is a schematic diagram of an exemplary embodiment of an electrochemical double layer capacitor (ECDL) device in accordance with the presently disclosed subject matter. [Figure 3A] 1 is a top view of an exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter. [Figure 3B] 1 is a side elevational view of an exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter. [Figure 3C] 3A / 3B show similar exemplary embodiments according to the presently disclosed subject matter. [Figure 4A] FIG. 2 is a top view of another exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter. [Figure 4B] FIG. 2 is a side elevational view of another exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter. [Figure 4C] 4A / 4B show similar exemplary embodiments according to the presently disclosed subject matter. [Diagram 5] 1 is a graph of an exemplary room temperature load life (at 2.8V load) versus percentage change in equivalent series resistance (ESR) for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 6] 1 is a graph of exemplary room temperature load life (at 2.8V load) versus percentage change in capacitance for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 7] 1 is a graph of an exemplary room temperature load life (at 2.8V load) versus percentage change in leakage current for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 8] 1 is a graph of shelf life versus percentage change in ESR at exemplary temperatures of 75° C., 85° C., and 105° C., respectively, for exemplary embodiments in accordance with the presently disclosed subject matter. [Figure 9] 1 is a graph of shelf life versus percent change in capacitance at exemplary temperatures of 75° C., 85° C., and 105° C., respectively, for exemplary embodiments according to the presently disclosed subject matter. [Figure 10] 1 is a graph of an exemplary load life versus percentage change in leakage current (at a temperature of 70° C. and a load of 2.2 V) for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 11] 1 is a graph of an exemplary load life versus percentage change in capacitance (at a temperature of 50° C. and a load of 2.5 V) for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 12] 1 is a graph of an exemplary load life versus percentage change in leakage current (at a temperature of 50° C. and a load of 2.5 V) for an exemplary embodiment in accordance with the presently disclosed subject matter. [Figure 13] 1 is an exemplary ESR vs. temperature graph for an example embodiment in accordance with the presently disclosed subject matter. [Figure 14] 1 is an example capacitance versus temperature graph for an example embodiment in accordance with the presently disclosed subject matter. [Figure 15] 4 is an example leakage current versus temperature graph for an example embodiment in accordance with the subject matter disclosed herein. [Figure 16] 1 is a graph of an example GSM waveform showing both voltage and current versus time that may be used for voltage cycling testing performed using example embodiments according to the presently disclosed subject matter. [Figure 17] 1 is a graph of the percentage change in ESR versus cycle number in voltage cycles for an exemplary GSM waveform using an exemplary embodiment according to the presently disclosed subject matter. [Figure 18] 1 is a graph of an example triangular waveform showing voltage versus time that may be used in a voltage cycling test performed using an example embodiment according to the presently disclosed subject matter. [Figure 19]1 is a graph of the percentage change in ESR versus cycle number for an exemplary triangular waveform voltage cycle using an exemplary embodiment according to the presently disclosed subject matter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Repeated use of references and descriptions throughout the specification and the accompanying drawings is intended to represent same or analogous features, elements or steps of the subject matter disclosed herein.

[0044] As discussed in the Subject Matter Summary section, the presently disclosed subject matter generally relates to certain organic electrolytic capacitor devices and related techniques and methodologies for fabrication and / or installation. More particularly, the presently disclosed subject matter relates to improved designs for certain ultra-thin, extremely low ESR supercapacitor components and energy storage component assemblies and related methodologies.

[0045] Selected combinations of aspects of the disclosed technology correspond to multiple different embodiments of the subject matter disclosed herein. It should be noted that each of the exemplary embodiments shown and discussed herein does not imply a limitation of the subject matter disclosed herein. Features or steps shown or described as part of one embodiment can be used in combination with aspects of another embodiment to produce further embodiments. Furthermore, certain features may be replaced with similar devices or features not expressly mentioned that perform the same or similar functions.

[0046] Reference will now be made in detail to the preferred exemplary embodiments, for which FIG. 2 shows a schematic diagram of an exemplary electrochemical double-layer capacitor (ECDL) device constructed according to the presently disclosed technology. To better understand the presently disclosed subject matter, some additional background to ECDL devices is provided as follows: FIG. 1 shows an exploded isometric view of the layers comprising an exemplary prior art electrochemical energy storage device. See also, for example, FIG. 4 of commonly owned U.S. Patent No. 5,399,343 (Meitav et al.), which relates to electrochemical energy storage devices, the complete disclosure of which is incorporated herein in its entirety for all purposes. Generally speaking, such double-layer capacitors have certain advantages over electronic technologies.

[0047] Considering how electrochemical (ECDL) capacitors work, the most important difference from electronic capacitors is that the charge transfer is carried out by electrons in electronic capacitors, and by electrons and ions in ECDL devices. The anions and cations contained in double layer supercapacitors are contained in an electrolyte, which can be a liquid (possibly an aqueous or organic solution) or a solid. The solid electrolyte is often a conducting polymer.

[0048] Electrons are moving relatively quickly and therefore transfer charge "instantly". Ions, however, must move relatively slowly from the anode to the cathode. Thus, a finite amount of time is required to reach the full nominal capacitance of the device. The nominal capacitance is usually measured at 1 second. The various differences between EDLCs (electrochemical double layer capacitors) and electronic capacitors can be summarized as follows: ·A capacitor basically consists of two conductive plates (electrodes) separated by a layer of dielectric material which can be ceramic, plastic film, paper, aluminum oxide, etc. ·EDLCs do not use a separate dielectric interphase separating the electrodes. EDLCs utilize the charge separation that forms across the electrode-electrolyte interface. ·EDLCs consist of two types of charge carriers: ionic species on the electrolyte side, and electronic species on the electrode side.

[0049] The exploded isometric view of FIG. 1 shows the layers that comprise a typical prior art electrochemical energy storage device.

[0050] In this example, a case or frame provides the form for the common internal cell structure, and the outer layers (top and bottom) of the structure are composed of the cell case material with the anode element. A pair of current collectors may be provided, as shown in typical prior art FIG. 1. They may comprise, for example, a first layer of conductive polymer in contact with the cell electrode. The second conductive structure (layer) may be a metal, alloy, metallic film, or combination or mixture thereof, preferably exhibiting high conductivity, low contact resistance, and good adhesion properties to the conductive polymer layer or polymer composite.

[0051] One current collector may be attached to the lower cell casing, and the other current collector may be adjacent to the electrode that comprises the cathode in that arrangement. Thus, a layer of insulating material is shown between such cathode electrode and the anode in the cell casing. Each current collector shown is otherwise adjacent to a layer of carbon, and each of the carbon layers may be adjacent to a separator layer.

[0052] 2 shows a schematic diagram of an exemplary electrochemical double layer capacitor (ECDL) device constructed according to the presently disclosed technology, thus comprising an extremely low ESR ECDL device or a pulsed supercapacitor (suitable for providing a pulseable energy storage device). As shown, a separator layer is sandwiched between a pair of electrodes having an electrolyte, and the electrodes are sandwiched from the outside by a pair of current collectors. Such electrolyte preferably comprises an organic electrolyte. For some of the presently disclosed embodiments, a propylene carbonate (PC) electrolyte is preferred.

[0053] Such an arrangement has been shown to be capable of providing carbon-carbon (CC) capacitors with overall electrical properties of low ESR of 50 to 300 mΩ (i.e., resistivity of about 1.5 Ω·cm2 or less of electrode area, and in some instances 1.3 Ω·cm2 or less of electrode area), capacitance of 1 to 10 F (i.e., capacitance density of at least about 10 Farads per cc of active electrode volume), leakage current <50 μA, and voltage rating of 2.1 to 4.2 V.

[0054] In one exemplary application, a constant output of 1 W with a 4 second back up is as follows: Expected total ΔV = 1V ·ΔV(total)=ΔVesr+ΔVcap ΔVesr=0.25*0.1=0.025V (small drop) - Operates at 4V with ΔVcap of approximately 1V · C estimated from I=C*dV / dt approx. 1 Farad (Note that the voltage drop due to ESR is small, so doubling it has little effect.)

[0055] For another exemplary application, key electrical parameters that may be achieved by the presently disclosed technology include a capacitance of 1 F, a voltage rating of 4.2 V, a temperature operating range rating of -40° to 70° C., and an ESR of 100 mΩ.

[0056] The subject matter disclosed herein helps address the demand for increased power density, in part by using organic electrolytes instead of water-based electrolytes, and in part by using extremely thin designs (with the ability to stack layers), such as as small as 0.5 mm (or less) instead of prior art devices on the order of about 2 to 3 mm. Such ultra-thin configurations with the ability to be placed in parallel with a battery can increase battery life (use life) by 35%.

[0057] Another advantage of the presently disclosed subject matter is the relatively increased operating temperature range. Preferably, an electrolyte is used that has a boiling point above 200°C, e.g., up to 240°C. A preferred example includes at least some propylene carbonate (PC). If the practitioner of the presently disclosed subject matter uses thermally stable materials for the seals, the electrolyte and the terminals are not a constraint on the high temperature operating range. For example, an increased temperature range capability of 90°C at half rated voltage is possible, along with a storage capability at 105°C where the device still retains its shape.

[0058] In general, aspects of the presently disclosed subject matter that contribute to its ability to withstand relatively high temperatures while also retaining its shape relate to the manufacturing process. Advantageously, water / moisture is excluded from the manufacturing environment to a very high degree. For example, it is known that the manufacture of lithium oxide batteries attempts to maintain 0.01 to 0.1% moisture, which corresponds to 100 to 1000 ppm water. However, in this example, the moisture environment is limited to only 0.001%, which corresponds to 10 ppm, thereby achieving advantageous thermal shape resistance in combination with other aspects disclosed herein. At that very low moisture environment level, any increase in response to performance at the limits of the intended thermal range can be ignored.

[0059] The carbon-carbon capacitor (CC-cap) structure is achieved in part by the use of an extremely thin separator layer between each layer. As will be understood by those skilled in the art from the full disclosure herein, further embodiments can be formed in which thin capacitors are stacked to selectively achieve increased capacitance and / or voltage. For example, two 2.1 volt devices arranged in series can each serve as a replacement for a 3.6V lithium battery. The resulting ultra-thin presently disclosed subject matter provides small embodiments with significantly reduced dimensions, enabling the possibility of positioning the battery in an add-on case for a mobile phone, for example. In general, the presently disclosed ECDL electrochemical double layer capacitor (ECDL) subject matter can serve as a supercap or ultracap, providing an energy storage device useful in various other product configurations. A further example is for use in or as an uninterruptible power supply (UPS). Of course, as will be understood by those skilled in the art, various configurations can result from the series and / or parallel connected embodiments to increase capacitance and / or voltage.

[0060] In general, the subject matter disclosed herein relates to an ultra-thin version of an extremely low ESR supercapacitor that achieves increased power density in a supercapacitor through the use of a very low height design using organic electrolyte materials. The resulting subject matter provides an extremely thin device with a minimum thickness of less than 0.5 mm compared to the usual prior art standard of 2 to 3 mm thickness. The new design also has significantly enhanced high temperature performance along with increased battery life. The extremely thin design disclosed herein combined with high temperature tolerant materials and the manufacturing methodology disclosed herein provide superior results in terms of extremely low ESR characteristics. Furthermore, the use of an embodiment that defines a propylene carbonate (PC) electrolyte and has case dimensions of approximately 50 mm long by 40 mm wide by 0.5 mm thick can also provide extremely low ESR characteristics.

[0061] With regard to extremely low ESR characteristics, results on the order of less than 150 milliohms are contemplated, even in combination with operation at elevated temperatures or at storage temperatures up to 105°C.

[0062] Figures 3A and 3B are top and side elevation views, respectively, of an exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter as shown in more detail in this Figure 2. As shown, the dimensions of an exemplary case for such a single cell arrangement are 50 mm long x 40 mm wide x 0.5 mm thick, and there is a pair of terminals associated with such case. Figure 3C shows a similar exemplary embodiment according to the presently disclosed subject matter of Figures 3A and 3B.

[0063] Figures 4A and 4B are top and side elevation views, respectively, of another exemplary embodiment of an organic electrolytic capacitor device according to the presently disclosed subject matter, showing an arranged pair of cells of a structure as shown in more detail in this Figure 2. As shown, the dimensions of an exemplary case for such a dual (paired) cell arrangement are 50 mm long by 80 mm wide by 0.5 mm thick, and there are two pairs of terminals associated with such an embodiment. Figure 4C shows a similar example embodiment according to the presently disclosed subject matter of Figures 4A and 4B.

[0064] 5, 6 and 7 are graphs of exemplary room temperature load life (at 2.8V load) versus percent change in equivalent series resistance (ESR), capacitance and leakage current for exemplary embodiments based on the subject matter disclosed herein. As shown, the graphs span over 4000 hours of time exposure to demonstrate reliability test data. The reflected data shows excellent commercial performance in all tested categories. An additional aspect of such reliability testing is that, as will be understood by those skilled in the art, the test voltage (2.8VT) is purposely much higher than the rated voltage (2.1VR). Since it will be understood by those skilled in the art that electrochemical devices are in practice typically used at or below the rated voltage, such an approach to testing is sufficient to demonstrate that the tested device is considered robust. Thus, the test voltage (such as 2.8VT) in this specification is not intended as an indication of a higher rated voltage (such as 2.1VR).

[0065] 8 graphically illustrates shelf life reliability test data (axis >4000 hours) at exemplary temperatures of 75° C., 85° C., and 105° C., respectively, for an exemplary embodiment based on the presently disclosed subject matter. The data in FIG. 8 addresses the percentage change in ESR, while the data in FIG. 9 addresses the percentage change in capacitance. As shown, the presently disclosed subject matter exhibits superior performance even when operating over an extended temperature range.

[0066] FIG. 10 is an exemplary load life versus percentage change in leakage current graph for an exemplary embodiment according to the subject matter disclosed herein. The measurements are again in terms of reliability test data and address operation at a temperature of 70° C. and a load of 2.2 V. FIGs. 11 and 12 are similar graphs, but encompass operation at a temperature of 50° C. and a load of 2.5 V. The graphs in FIGs. 11 and 12 also specifically show the percentage change in capacitance and leakage current, respectively.

[0067] Figures 13, 14 and 15 show graphs of various electrical properties versus temperature for example embodiments according to the presently disclosed subject matter. Figure 13 shows the graphed percentage change in ESR, indicating that from 0°C onwards, the ESR remains within about ±50% of the room temperature value, thus achieving a very low ESR over a wide temperature range. Figure 14 shows the change in capacitance, which only shows a change of about ±25% over the range from -40°C to 70°C. Figure 15 also shows stable leakage current performance over the indicated temperature range.

[0068] Figures 16-19 graphically illustrate suitable data for voltage cycling testing of example embodiments in accordance with the presently disclosed subject matter using a frequency generator and power amplifier test arrangement. In particular, Figures 16 and 17 relate to an example GSM waveform test usage, and Figures 18 and 19 relate to an example triangular waveform test usage. The sample GSM waveform shown relates to a 217 Hz GSM square wave with a 25% duty cycle, shown over a test range of 1.4V to 2.8V. The sample triangular waveform shown reflects a 0.1 Hz triangular wave, also over a test range of 1.4V to 2.8V.

[0069] More specifically, Figure 16 shows both voltage and current versus time for an exemplary GSM wave that may be used for voltage cycling tests performed with exemplary embodiments according to the presently disclosed subject matter, and Figure 17 tracks durability performance as a percentage change in exemplary ESR over 1 million cycles of such a test waveform. Figure 18 shows voltage versus time for an exemplary triangular wave that may be used for voltage cycling tests performed with exemplary embodiments according to the presently disclosed subject matter, and Figure 19 tracks durability performance as a percentage change in exemplary ESR over 150,000 cycles of such a test waveform. Both Figures 17 and 19 reflect generally negligible changes in ESR performance over such durability cycling tests.

[0070] In summary, an exemplary embodiment of the presently disclosed subject matter may have exemplary case dimensions of 50 mm long x 40 mm wide x 0.5 m thick, with a pair of terminals associated with such case (see subject Figures 3A and 3B), and may preferably use at least some propylene carbonate (PC) electrolyte. Such an exemplary embodiment may have a voltage rating (Vr) of 2.1 volts and a capacitance of 2.1 F / cc. It may provide excellent performance at 90°C and 0.5 rated volts operation. At the same time, it may avoid blistering and maintain dimensional stability at storage temperatures up to 105°C, while also maintaining an extremely low ESR of 150 milliohms and a normalized ESR / Cap of about 72 milliohms / cc / F.

[0071] In general, the embodiments disclosed herein can exhibit excellent high power pulse capability along with low leakage current for capacitance densities greater than about 10 F / cc for the volume of the active electrode. Test data also shows no degradation of half rated voltage at elevated temperatures, and maintained shelf life and enhanced temperature range performance, including at relatively high temperatures (such as 105° C.).

[0072] While the subject matter disclosed herein has been described in detail with reference to specific embodiments thereof, those skilled in the art will appreciate that, upon gaining an understanding of the foregoing, they may readily adapt the techniques disclosed herein to modifications or additions to such embodiments, variations thereof, and / or equivalents thereof. Accordingly, the scope of the present disclosure is intended to be illustrative rather than limiting, and the subject disclosure does not exclude including such modifications, variations, and / or additions to the subject matter disclosed herein, as would be readily apparent to those skilled in the art.

Claims

[Claim 1] each pair of internal electrodes having an electrolyte; a separator layer between each of the electrodes; and a pair of respective current collectors, each one of said current collectors being on an outer side of each of said electrodes; a case enclosing the current collectors and having a respective pair of terminals connected to the current collectors; wherein the contents of the case have a minimum thickness of less than 0.5 millimeters.

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