Ultracapacitor assembly

Abstract

An ultracapacitor assembly is provided. The ultracapacitor assembly includes a plurality of ultracapacitors. The ultracapacitor assembly further includes a first bus bar and a second bus bar. The second bus bar is spaced apart from the first bus bar. The ultracapacitor assembly includes a discharge resistor coupled between the first bus bar and the second bus bar. The ultracapacitor assembly further includes a first plurality of switching devices and a second plurality of switching devices. Each switching device in the first plurality of switching devices is coupled between the first bus bar and a corresponding ultracapacitor of the plurality of ultracapacitors to selectively couple the corresponding ultracapacitor to the discharge resistor via the first bus bar. Each switching device in the second plurality of switching devices is coupled between the second bus bar and a corresponding ultracapacitor to selectively couple the corresponding ultracapacitor to the discharge resistor via the second bus bar.

Description

[Technical Field]

[0001] Priority Claim This application claims priority to U.S. Provisional Patent Application No. 63 / 033,400, filed on 2 June 2020, entitled "Ultracapacitor Assembly," which is incorporated herein by reference. [Background technology]

[0002] Electrical energy storage cells are widely used to power electronic, electromechanical, electrochemical, and other useful devices. For example, a double-layer ultracapacitor can use a pair of polarizing electrodes containing carbon particles (e.g., activated carbon) impregnated with a liquid electrolyte. Due to the effective surface area of ​​the particles and the small spacing between the electrodes, a large capacitance value can be achieved. Individual double-layer capacitors can be combined to form modules with increased output voltage or increased energy capacity. [Overview of the project] [Means for solving the problem]

[0003] One aspect of the present disclosure relates to an ultracapacitor. An ultracapacitor assembly includes a plurality of ultracapacitors. The ultracapacitor assembly further includes a first busbar and a second busbar. The second busbar is positioned apart from the first busbar. The ultracapacitor assembly includes a discharge resistor coupled between the first busbar and the second busbar. The ultracapacitor assembly further includes a first plurality of switching devices and a second plurality of switching devices. Each switching device in the first plurality of switching devices is coupled via the first busbar between the first busbar and a corresponding ultracapacitor among the plurality of ultracapacitors in order to selectively couple a corresponding ultracapacitor to a discharge resistor. Each switching device in the second plurality of switching devices is coupled via the second busbar between the second busbar and a corresponding ultracapacitor in order to selectively couple a corresponding ultracapacitor to a discharge resistor.

[0004] Another aspect of the present disclosure relates to a method for discharging one or more ultracapacitors. The method includes the step of controlling the operation of a first switching device to couple one or more ultracapacitors to a discharge resistor via a first busbar. The method further includes the step of controlling the operation of a second switching device to couple one or more ultracapacitors to a discharge resistor via a second busbar located spaced apart from the first busbar. The method further includes supplying current from one or more ultracapacitors to a discharge resistor when one or more ultracapacitors are coupled to the discharge resistor via the first and second busbars.

[0005] Other features and aspects of this disclosure are described in further detail below.

[0006] The full and possible disclosure of this disclosure, intended for those skilled in the art, including its best mode, is described in more detail in the remainder of this specification with reference to the accompanying drawings. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an ultracapacitor assembly according to an exemplary embodiment of the present disclosure. [Figure 2] This figure shows a single ultracapacitor coupled to a discharge resistor in an ultracapacitor assembly according to an exemplary embodiment of the present disclosure. [Figure 3] This figure shows a plurality of ultracapacitors coupled to a discharge resistor in an ultracapacitor assembly according to an exemplary embodiment of the present disclosure. [Figure 4] This is a flowchart illustrating an exemplary method for balancing one or more ultracapacitors in an ultracapacitor assembly according to an exemplary embodiment of the present disclosure. [Figure 5] This figure shows the spatial arrangement of components of an ultracapacitor assembly according to an exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The repeated use of reference numerals in this specification and drawings is intended to represent the same or similar forms or elements of the present disclosure.

[0009] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit broader embodiments of the disclosure, and that broader embodiments are embodied in exemplary configurations.

[0010] Exemplary aspects of this disclosure relate to an ultracapacitor assembly. The ultracapacitor assembly may include a plurality of ultracapacitors. The ultracapacitor assembly may further include a first busbar and a second busbar. The second busbar may be positioned apart from the first busbar. More specifically, the second busbar may be positioned apart from the first busbar such that a plurality of ultracapacitors are positioned between the first busbar and the second busbar. The ultracapacitor assembly may include a discharge resistor coupled between the first busbar and the second busbar. For example, in some embodiments, the discharge resistor may be coupled to the first busbar and the second busbar via one or more conductors (e.g., wires).

[0011] An ultracapacitor assembly may include a first plurality of switching devices and a second plurality of switching devices. Each switching device in the first plurality of switching devices may be coupled between a first busbar and a corresponding ultracapacitor among the plurality of ultracapacitors in order to selectively couple a corresponding ultracapacitor to a discharge resistor. Furthermore, each switching device in the second plurality of switching devices may be coupled between a second busbar and a corresponding ultracapacitor among the plurality of ultracapacitors in order to selectively couple a corresponding ultracapacitor to a discharge resistor. When one or more of the plurality of ultracapacitors are coupled to the first busbar and the second busbar, one or more ultracapacitors can be coupled to a discharge resistor. In this way, when one or more ultracapacitors are coupled to the first busbar and the second busbar via the switching devices in the first plurality of switching devices and the switching devices in the second plurality of switching devices, one or more ultracapacitors can supply discharge current to the discharge resistor.

[0012] The total number of switching devices in the first and second sets of switching devices can be greater than the total number of ultracapacitors. Furthermore, the total number of switching devices in the first set of switching devices can be the same as the total number of switching devices in the second set of switching devices. In some embodiments, each switching device in the first set of switching devices and each switching device in the second set of switching devices may include field-effect transistors or other suitable switching devices (e.g., semiconductor switching devices). However, it should be noted that any suitable type of switching device may be used to selectively couple ultracapacitors to the first and second busbars.

[0013] The ultracapacitor assemblies described herein offer numerous technical advantages and benefits. For example, the first and second sets of switching devices can enable coupling one or more of the ultracapacitors to a common discharge resistor. In this way, two or more ultracapacitors in an ultracapacitor assembly can be balanced and / or selectively discharged at once without requiring a large number of discharge resistors. Furthermore, since two or more of the ultracapacitors can be balanced and / or discharged using a common discharge resistor, the wiring associated with the ultracapacitor assembly can be reduced.

[0014] Next, referring to the figures, Figures 1 to 3 show an ultracapacitor assembly 100 according to an exemplary embodiment of the present disclosure. As shown, the ultracapacitor assembly 100 may include a plurality of ultracapacitors 110. In addition, the ultracapacitor assembly 100 may include a first busbar 120 and a second busbar 130. The second busbar 130 may be positioned at a distance from the first busbar 120. More specifically, the second busbar 130 may be positioned at a distance from the first busbar 120 such that the plurality of ultracapacitors 110 are positioned between the first busbar 120 and the second busbar 130. The ultracapacitor assembly 100 may further include a discharge resistor 140 coupled between the first busbar 120 and the second busbar 130. For example, in some embodiments, the discharge resistor 140 may be coupled to the first busbar 120 and the second busbar 130 via one or more conductors 142 (e.g., wires).

[0015] The ultracapacitor assembly 100 may include a first plurality of 150 switching devices 152 and a second plurality of 160 switching devices 162. Each switching device in the first plurality of 150 switching devices 152 can be coupled via a first busbar 120 to a corresponding ultracapacitor from a plurality of ultracapacitors 112 in order to selectively couple the corresponding ultracapacitor to a discharge resistor 140. Furthermore, each switching device in the second plurality of 160 switching devices 162 can be coupled via a second busbar 130 to a corresponding ultracapacitor from a plurality of ultracapacitors 112 in order to selectively couple the corresponding ultracapacitor to a discharge resistor 140. When one or more of the multiple ultracapacitors 112 are coupled to the discharge resistor 140 via the switching devices 152 in the first multiple 150 switching devices 152 and the switching devices 162 in the second multiple 160 switching devices 162, one or more ultracapacitors can supply discharge current to the discharge resistor 140.

[0016] As shown in the figure, the total number of switching devices 152 and 162 in the first set of 150 switching devices 152 and the second set of 160 switching devices 162 can be greater than the total number of ultracapacitors 112. For example, as can be seen in Figure 1, the total number of switching devices 152 and 162 in the ultracapacitor assembly 100 is 6, while the total number of ultracapacitors 112 is 5. Furthermore, the total number of switching devices 152 in the first set of 150 switching devices 152 can be the same as the total number of switching devices 162 in the second set of 160 switching devices 162. In some embodiments, each switching device in the first set of 150 switching devices 152 and the second set of 160 switching devices 162 can include a field-effect transistor. However, it should be recognized that the switching devices 152 and 162 can include any preferred type of switching device configured to selectively couple one or more of the multiple ultracapacitors 112 to the discharge resistor 140 via the first busbar 120 and the second busbar 130, respectively.

[0017] As shown in the figures, the first set of 150 switching devices 152 and the second set of 160 switching devices 162 can be configured to be set to a first state or configuration (Figure 1) and a second state or configuration different from the first configuration (Figures 2 and 3). When the first set of 150 switching devices 152 is in the first configuration, the multiple ultracapacitors 112 are disconnected from the first busbar 120. Similarly, when the second set of 160 switching devices 162 is in the first configuration, the multiple ultracapacitors 112 are disconnected from the second busbar 130. In this way, when both the first set of 150 switching devices 152 and the second set of 160 switching devices 162 are in the first configuration, the multiple ultracapacitors 112 can be disconnected from the discharge resistor 140.

[0018] Conversely, when the switching devices 152 in the first plurality of 150 switching devices 152 are in the second configuration (Figures 2 and 3), and the switching devices 162 in the second plurality of 160 switching devices 162 are in the second configuration, one or more of the plurality of ultracapacitors 112 can be coupled to the discharge resistor 140. More specifically, when both the switching devices 152 in the first plurality of 150 switching devices 152 and the switching devices 162 in the second plurality of 160 switching devices 162 are in the second configuration (Figures 2 and 3), one or more ultracapacitors can be coupled in series with the discharge resistor 140. In this way, one or more ultracapacitors can be balanced (e.g., selectively discharged) through the discharge resistor 140. More specifically, one or more ultracapacitors can supply current to the discharge resistor 140.

[0019] As shown in FIGS. 2 and 3, any suitable number of ultracapacitors can be coupled to the discharge resistor 140 via a first plurality 150 of switching devices 152 and a second plurality 160 of switching devices 162. For example, the first plurality 150 of switching devices 152 and the second plurality 160 of switching devices 162 can be controlled such that only one of the plurality of ultracapacitors 112 is coupled to the discharge resistor 140 at a time as shown in FIG. 2. Alternatively, as shown in FIG. 3, the first plurality 150 of switching devices 152 and the second plurality 160 of switching devices 162 can be controlled such that a number of ultracapacitors can be coupled to the discharge resistor 140 simultaneously. For example, in some embodiments, the first plurality 150 of switching devices 152 and the second plurality 160 of switching devices 162 can be controlled such that each of the plurality of ultracapacitors 112 can be coupled to the discharge resistor 140 simultaneously. In such embodiments, each of the plurality of ultracapacitors 112 can be balanced (e.g., discharged) simultaneously without requiring a separate discharge resistor for each of the plurality of ultracapacitors 112.

[0020] FIG. 4 shows a flow diagram of a method 300 according to an exemplary embodiment of the present disclosure. The method 300 can be implemented, for example, using the ultracapacitor assembly shown in the figure. FIG. 4 shows steps executed in a particular order for illustration and discussion purposes. Those skilled in the art will understand that, using the disclosure provided herein, various steps of any of the methods disclosed herein can be omitted, rearranged, executed simultaneously, extended, modified, and / or adapted in various ways without departing from the scope of the present disclosure.

[0021] In (302), method 300 can include controlling the operation of a first switching device to couple one or more ultracapacitors to a discharge resistor via a first bus bar. For example, the step of controlling the operation of the first switching device can include providing one or more control signals related to coupling the ultracapacitor to the discharge resistor via the first bus bar.

[0022] In (304), method 300 can include controlling the operation of a second switching device to couple one or more ultracapacitors to a discharge resistor via a second bus bar disposed remotely from the first bus bar. For example, the step of controlling the operation of the second switching device can include providing one or more control signals related to coupling the ultracapacitor to the discharge resistor via the second bus bar. In some embodiments, the ultracapacitor coupled to the discharge resistor via the second bus bar can be the same as the ultracapacitor coupled to the discharge resistor via the first bus bar in (302). In an alternative embodiment, the ultracapacitor coupled to the discharge resistor via the second bus bar may be different from the ultracapacitor coupled to the discharge resistor via the first bus bar. In such an embodiment, two different ultracapacitors (e.g., a first ultracapacitor, a second ultracapacitor) can be coupled in series with each other. In this way, both ultracapacitors can be coupled to the discharge resistor.

[0023] In (306), method 300 may include the step of supplying current from one or more ultracapacitors to a discharge resistor when one or more ultracapacitors are coupled to the discharge resistor via a first busbar and a second busbar. In some embodiments, the ultracapacitors can be coupled in series with one another. In such embodiments, a number of ultracapacitors can be coupled to a discharge resistor at once. In this way, each ultracapacitor coupled to the discharge resistor via the first busbar and the second busbar can supply current to the discharge resistor. Thus, a number of ultracapacitors can be equilibrated (e.g., discharged) at once without requiring a separate discharge resistor for each of the ultracapacitors.

[0024] Next, referring to Figure 5, the spatial arrangement of components of an exemplary embodiment of the present disclosure of an ultracapacitor assembly 400 is provided. As shown, the ultracapacitor assembly 400 may include a plurality of ultracapacitors 110 as discussed above with reference to Figure 1. In addition, the ultracapacitor assembly 400 may include a first busbar 120 and a second busbar 130. As shown, the second busbar 130 may be positioned away from the first busbar 120 along the axial direction A of the ultracapacitor assembly 400. More specifically, the second busbar 130 may be positioned away from the first busbar 120 along the axial direction A such that the plurality of ultracapacitors 110 are positioned between the first busbar 120 and the second busbar 130 along the axial direction A. In some embodiments, the plurality of ultracapacitors 110 may be positioned away from each other along the radial direction R of the ultracapacitor assembly 400.

[0025] The ultracapacitor assembly 400 may include the discharge resistor 140 discussed above with reference to Figure 1. As shown in the figure, the discharge resistor 140 can be coupled between the first busbar 120 and the second busbar 130. Thus, the discharge resistor 140 can be positioned between the first busbar 120 and the second busbar 130 along the axial direction A, like multiple ultracapacitors 110.

[0026] The ultracapacitor assembly 400 may include a first plurality of 150 switching devices 152 and a second plurality of 160 switching devices 162 as discussed above with reference to Figures 1 to 3. As shown in the figures, each switching device 152 in the first plurality of 150 can be coupled between the first bus bar 120 and the corresponding ultracapacitor among the plurality of ultracapacitors 110. In this way, each switching device 152 in the first plurality of 150 can be positioned between the first bus bar 120 and the plurality of ultracapacitors 110 along the axial direction A. Furthermore, each switching device 162 in the second plurality of 160 can be coupled between the second bus bar 130 and the corresponding ultracapacitor among the plurality of ultracapacitors 110. In this way, each switching device 162 in the second plurality of 160 can be positioned between the second bus bar 130 and the plurality of ultracapacitors 110 along the axial direction A.

[0027] Any of the various different individual ultracapacitors can typically be used in a module according to the exemplary embodiments of this disclosure. However, in some embodiments, the ultracapacitor includes an electrode assembly and an electrolyte contained within a housing and optionally hermetically sealed. The electrode assembly may include, for example, a first electrode comprising a first carbonaceous coating (e.g., activated carbon particles) electrically coupled to a first current collector, and a second electrode comprising a second carbonaceous coating (e.g., activated carbon particles) electrically coupled to a second current collector. It should be understood that additional current collectors may be used if desired, particularly if the ultracapacitor comprises a large number of energy storage cells. The current collectors may be formed from the same or different materials. Nevertheless, each current collector is typically formed from a substrate comprising conductive metals, such as aluminum, stainless steel, nickel, silver, palladium, and alloys thereof. Aluminum and aluminum alloys are particularly preferred for use in this disclosure. The substrate may be in the form of foil, sheet, plate, mesh, etc. The substrate can also have a relatively small thickness, for example, about 200 micrometers or less, about 1 to about 100 micrometers in some embodiments, about 5 to about 80 micrometers in some embodiments, and about 10 to about 50 micrometers in some embodiments. Although not required, the surface of the substrate may optionally be roughened by washing, etching, blasting, etc.

[0028] In some embodiments, at least one, preferably both, of the first and second current collectors may further include a plurality of fiber-like whiskers protruding outward from the substrate. While not limited by theory, these whiskers are thought to effectively increase the surface area of ​​the current collector and, furthermore, improve the adhesion of the current collector to the corresponding electrode. This can allow for the use of relatively low binder content in the first and / or second electrodes, which can improve charge transfer, reduce interfacial resistance, and consequently result in a very low ESR value. Whiskers are typically formed from a material containing carbon and / or reaction products of carbon with a conductive metal. In one embodiment, for example, the material may include a carbide of a conductive metal such as aluminum carbide (Al4C3). Generally, a plurality of whiskers protrude outward from the substrate. Optionally, if desired, the whiskers may protrude from seed portions embedded within the substrate. Similar to whiskers, the seed portion can also be formed from a material containing carbon and / or reaction products of carbon with a conductive metal, such as a carbide of a conductive metal (e.g., aluminum carbide).

[0029] The method by which such whiskers are formed on the substrate may vary as desired. In one embodiment, for example, a conductive metal of the substrate is reacted with a hydrocarbon compound. Examples of such hydrocarbon compounds include paraffinic hydrocarbon compounds such as methane, ethane, propane, n-butane, isobutane, and pentane; olefinic hydrocarbon compounds such as ethylene, propylene, butene, and butadiene; acetylene hydrocarbon compounds such as acetylene; and any derivative or combination thereof. Generally, it is desirable that the hydrocarbon compound be in gaseous form during the reaction. Therefore, it may be desirable to use hydrocarbon compounds such as methane, ethane, and propane, which are in gaseous form when heated. Although not always necessary, the hydrocarbon compound is typically used in an amount ranging from about 0.1 parts by weight to about 50 parts by weight, and in some embodiments from about 0.5 parts by weight to about 30 parts by weight, based on 100 parts by weight of the substrate. To initiate the reaction between hydrocarbons and conductive metals, the substrate is generally heated in an atmosphere at a temperature of about 300°C or higher, in some embodiments above 400°C, and in some embodiments between about 500°C and about 650°C. The heating time depends on the exact temperature selected, but is typically in the range of about 1 hour to about 100 hours. The atmosphere typically contains a relatively small amount of oxygen to minimize the formation of dielectric films on the surface of the substrate. For example, the oxygen content of the atmosphere can be about 1 volume percent or less.

[0030] The first and second carbonaceous coatings are further electrically coupled to the first and second electron collectors, respectively. They may be formed from the same or different types of materials and may consist of one or more layers, but each carbonaceous coating typically includes at least one layer containing activated particles. In one embodiment, for example, the activated carbon layer may be directly positioned on the electron collector, or optionally, it may be just one layer of the carbonaceous coating. Examples of suitable activated carbon particles include, for example, coconut shell-based activated carbon, petroleum coke-based activated carbon, pitch-based activated carbon, polyvinylidene chloride-based activated carbon, phenol resin-based activated carbon, polyacrylonitrile-based activated carbon, and activated carbon from natural sources such as coal, charcoal, or other natural organic sources.

[0031] In some embodiments, it may be desirable to selectively control certain aspects of activated carbon particles, such as particle size distribution, surface area, and pore size distribution, to help improve the ion mobility of a certain type of electrolyte after being subjected to one or more charge-discharge cycles. For example, at least 50 volume percent of the particles (D50 size) may have a size ranging from about 0.01 to about 30 micrometers, in some embodiments from about 0.1 to about 20 micrometers, and in some embodiments from about 0.5 to about 10 micrometers. Similarly, at least 90 volume percent of the particles (D90 size) may have a size ranging from about 2 to about 40 micrometers, in some embodiments from about 5 to about 30 micrometers, and in some embodiments from about 6 to about 15 micrometers. The BET surface is about 900 m 2 From / g to approximately 3000m 2 / g, in some embodiments approximately 1000m 2 From / g to approximately 2500m 2 / g, in some embodiments approximately 1100m 2 From / g to approximately 1800m 2 It can also extend to / g.

[0032] In addition to having a specific size and surface area, the activated carbon particles can further include pores having a specific size distribution. For example, the amount of pores with a size less than about 2 nanometers (i.e., "micropores") can be defined as about 50 volume % or less of the total pore volume, about 30 volume % or less in some embodiments, and a pore volume of from 0.1 volume % to 15 volume % in some embodiments. Similarly, the amount of pores with a size between about 2 nanometers and about 50 nanometers (i.e., "mesopores") can be from about 20 volume % to about 80 volume %, from about 25 volume % to about 75 volume % in some embodiments, and from about 35 volume % to about 65 volume % in some embodiments. Finally, the amount of pores with a size greater than about 50 nanometers (i.e., "macropores") can be from about 1 volume % to about 50 volume %, from about 5 volume % to about 40 volume % in some embodiments, and from about 10 volume % to about 35 volume % in some embodiments. The total pore volume of the carbon particles can range from about 0.2 cm 3 / g to about 1.5 cm 3 / g, from about 0.4 cm 3 / g to about 1.0 cm 3 / g in some embodiments, and the median pore width can be about 8 nanometers or less, from about 1 to about 5 nanometers in some embodiments, and from about 2 to about 4 nanometers in some embodiments. The pore size and total pore volume can be measured using nitrogen adsorption and analyzed by the Barrett-Joyner-Halenda ("BJH") technique.

[0033] If desired, a binder may be present in the first and / or second carbonaceous coating in an amount of about 60 parts or less per 100 parts of carbon, 40 parts or less in some embodiments, and about 1 to about 25 parts in some embodiments. The binder may constitute, for example, about 15% by weight or less of the total weight of the carbonaceous coating, about 10% by weight or less in some embodiments, and about 0.5% to about 5% by weight in some embodiments. Any of a variety of suitable binders may be used for the electrode. For example, water-insoluble organic binders, such as styrene-butadiene copolymer, polyvinyl acetate homopolymer, vinyl acetate-ethylene copolymer, vinyl acetate-acrylic copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl chloride-vinyl acetate terpolymer, acrylic polyvinyl chloride polymer, acrylic polymer, nitrile polymer, fluoropolymer such as polytetrafluoroethylene or polyvinylidene fluoride, polyolefins, and mixtures thereof, may be used in some embodiments. Water-soluble organic binders, such as polysaccharides and their derivatives, may also be used. In one particular embodiment, the polysaccharide may be a nonionic cellulose ether, e.g., alkyl cellulose ether (e.g., methylcellulose and ethylcellulose); hydroxyalkyl cellulose ether (e.g., hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylhydroxybutylcellulose, hydroxyethylhydroxypropylcellulose, hydroxyethylhydroxybutylcellulose, hydroxyethylhydroxypropylhydroxybutylcellulose, etc.); alkylhydroxyalkyl cellulose ether (e.g., methylhydroxyethylcellulose, methylhydroxypropylcellulose, ethylhydroxyethylcellulose, ethylhydroxypropylcellulose, methylethylhydroxyethylcellulose, and methylethylhydroxypropylcellulose); carboxyalkyl cellulose ether (e.g., carboxymethylcellulose); and similar, as well as any of the aforementioned protonated salts such as sodium carboxymethylcellulose.

[0034] Other materials may be used further within the activated carbon layers of the first and / or second carbonaceous coating, and / or within other layers of the first and / or second carbonaceous coating. For example, in some embodiments, conductivity can be further increased using conductivity enhancers. Exemplary conductivity enhancers may include, for example, carbon black, graphite (natural or artificial), graphite, carbon nanotubes, nanowires or nanotubes, metal fibers, graphene, and mixtures thereof. Carbon black is particularly preferred. When used, the conductivity enhancer typically constitutes about 60 parts or less per 100 parts of activated carbon particles in the carbonaceous coating, 40 parts or less in some embodiments, and about 1 to about 25 parts in some embodiments. The conductivity enhancer may constitute, for example, about 15% by weight or less of the total weight of the carbonaceous coating, about 10% by weight or less in some embodiments, and about 0.5% to about 5% by weight in some embodiments. Similarly, the activated carbon particles typically constitute 85% or more by weight of the carbonaceous coating, about 90% or more by weight in some embodiments, and about 95% to about 99.5% by weight in some embodiments.

[0035] The specific method for applying the carbonaceous coating to the current collector may vary, including printing (e.g., rotary gravure), spraying, slot-die coating, drop coating, and dipping coating. Regardless of the application method, the resulting electrode is typically dried at temperatures above about 100°C, above about 200°C in some embodiments, and between about 300°C and 500°C in some embodiments, to remove moisture from the coating. The electrode may also be compressed (e.g., calendered) to optimize the volumetric efficiency of the ultracapacitor. After any optional compression, the thickness of each carbonaceous coating may typically vary based on the desired electrical performance and operating range of the ultracapacitor. However, typically, the coating thickness is about 20 to about 200 micrometers, 30 to about 150 micrometers, and between about 40 to about 100 micrometers in some embodiments. The coating may be present on one or both sides of the current collector. Nevertheless, the thickness of the entire electrode (including the current collector and carbonaceous coating after optional compression) is typically in the range of about 20 to about 350 micrometers, about 30 to about 300 micrometers in some embodiments, and about 50 to about 250 micrometers in some embodiments.

[0036] The electrode assembly further typically includes a separator positioned between the first electrode and the second electrode. If desired, additional separators may be used in the electrode assembly. For example, one or more separators may be positioned on the first electrode, the second electrode, or both. The separator can help prevent electrical short circuits by electrically isolating one electrode from the other, while still allowing ion transport between the two electrodes. In some embodiments, the separator may include, for example, cellulose fiber materials (e.g., airlaid paper web, wet paper web), nonwoven fiber materials (e.g., polyolefin nonwoven web), woven fabrics, films (e.g., polyolefin film), etc. Cellulose fiber materials, including natural fibers and synthetic fibers, are particularly suitable for use in ultracapacitors. Specific examples of cellulose fibers suitable for use in separators include, for example, hardwood pulp fibers, softwood pulp fibers, rayon fibers, and regenerated cellulose fibers. Regardless of the specific material used, the separator typically has a thickness of about 5 to about 150 micrometers, about 10 to about 100 micrometers in some embodiments, and about 20 to about 80 micrometers in some embodiments.

[0037] The components of an electrode assembly may be assembled in various ways. For example, the electrodes and separators may be first folded, rolled up, stacked, or otherwise brought into contact together to form the electrode assembly. In one particular embodiment, the electrodes, separators, and an optional electrolyte may be rolled up into an electrode assembly having a "jelly-roll" configuration.

[0038] To form an ultracapacitor, the electrolyte is positioned in ionic contact with the first and second electrodes before, during, and / or after the electrodes and separators are assembled to form the electrode assembly. The electrolyte is typically non-aqueous in nature and therefore contains at least one non-aqueous solvent. To help extend the operating temperature range of the ultracapacitor, it is typically desirable that the non-aqueous solvent has a relatively high boiling point, e.g., about 150°C or higher, about 200°C or higher in some embodiments, and about 220°C to about 300°C in some embodiments. Particularly preferred high-boiling point solvents may include cyclic carbonate solvents such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. Of course, other non-aqueous solvents may also be used alone or in combination with cyclic carbonate solvents. Examples of such solvents include, for example, open-chain carbonates (e.g., dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc.), aliphatic monocarboxylates (e.g., methyl acetate, methyl propionate, etc.), lactone solvents (e.g., butyrolactone, valerolactone, etc.), nitriles (e.g., acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, etc.), amides (e.g., N,N-dimethylformamide, N,N-diethylacetamide, N-methylpyrrolidinone), alkanes (e.g., nitromethane, nitroethane, etc.), sulfur compounds (e.g., sulfolane, dimethyl sulfoxide, etc.); and similar.

[0039] The electrolyte may further contain at least one ionic liquid dissolved in a non-aqueous solvent. The concentration of the ionic liquid can be varied, but typically, it is desirable for the ionic liquid to be present at a relatively high concentration. For example, the ionic liquid may be present in an amount of about 0.8 moles (M) or more per liter of electrolyte, about 1.0 M or more in some embodiments, about 1.2 M or more in some embodiments, and about 1.3 to about 1.8 M in some embodiments.

[0040] Ionic liquids are typically salts having relatively low melting temperatures, e.g., below about 400°C, below about 350°C in some embodiments, from about 1°C to about 100°C in some embodiments, and from about 5°C to about 50°C in some embodiments. Salts contain cationic species and counterions. Cationic species include compounds having at least one heteroatom (e.g., nitrogen or phosphorus) as a "cationic center". Examples of such heteroatom compounds include, for example, unsubstituted or substituted organic quaternary ammonium compounds, e.g., ammonium (e.g., trimethylammonium, tetraethylammonium, etc.), pyridinium, pyridazinium, pyramidinium, pyrazinium, imidazolium, pyrazorium, oxazolium, triazolium, thiazolium, quinolinium, piperidinium, pyrrolidinium, quaternary ammonium spiro compounds in which two or more rings are joined together by a spiroatom (e.g., carbon, heteroatom, etc.), quaternary ammonium condensed ring structures (e.g., quinolinium, isoquinolinium, etc.), and similar compounds. In one particular embodiment, for example, the cation species may be an N-spironicyclic compound, such as a symmetric or asymmetric N-spironicyclic compound having a cyclic ring. An example of such a compound is the following structure

[0041] [ka] The compound has such that m and n are independently numbers from 3 to 7, and in some embodiments are 4 to 5 (e.g., pyrrolidinium or piperidinium).

[0042] Similarly, suitable counterions for cationic species include halogens (e.g., chlorides, bromides, iodides); sulfates or sulfonates (e.g., methyl sulfate, ethyl sulfate, butyl sulfate, hexyl sulfate, octyl sulfate, hydrogen sulfate, methane sulfonate, dodecylbenzene sulfonate, dodecyl sulfate, trifluoromethane sulfonate, heptadecafluorooctanesulfonate, sodium dodecylethoxysulfate, etc.); sulfosuccinates; amides (e.g., dicyanamide); imides (e.g., bis(pentafluoroethyl-sulfonyl)imide, bis(trifluoromethylsulfonyl)imide, bis(trifluoromethyl)imide, etc.); borates (e.g., tetrafluoroborate, tetrafluoroborate, tetrafluorosulfonyl) This may include anoborates, bis[oxalato]borate, bis[salicylate]borate, etc.); phosphates or phosphinates (e.g., hexafluorophosphate, diethyl phosphate, bis(pentafluoroethyl)phosphinate, tris(pentafluoroethyl)-trifluorophosphate, tris(nonafluorobutyl)trifluorophosphate, etc.); antimonates (e.g., hexafluoroantimonate); aluminates (e.g., tetrachloroaluminate); fatty acid carboxylates (e.g., oleate, isostearate, pentadecafluorooctanoate, etc.); cyanates; acetates; and similar substances, as well as any combination thereof.

[0043] Some examples of suitable ionic liquids include, for example, spiro-(1,1')-bipyrrolidinium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, spiro-(1,1')-bipyrrolidinium iodide, triethylmethylammonium iodide, tetraethylammonium iodide, methyltriethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate.

[0044] As described above, the ultracapacitor further includes a housing that holds the electrode assembly and electrolyte and is optionally hermetically sealed. The properties of the housing may vary as desired. In one embodiment, for example, the housing may include a metal container ("can") formed from tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), alloys thereof, composites thereof (e.g., metals coated with conductive oxides), and the like. Aluminum is particularly preferred for use in this disclosure. The metal container may have any of a variety of different shapes, such as cylindrical or D-shaped. Cylindrical containers are particularly preferred.

[0045] In another embodiment, for example, the housing may take the form of a flexible package that encloses the components of the ultracapacitor. The package generally includes a substrate having edges that extend between two ends and where the ends and overlapping side portions are fixedly and tightly joined together (e.g., by thermal welding). In this way, the electrolyte can be held within the package. The substrate typically has a thickness ranging from about 20 micrometers to about 1000 micrometers, in some embodiments from about 50 micrometers to about 800 micrometers, and in some embodiments from about 100 micrometers to about 600 micrometers.

[0046] The substrate may include any number of layers desired to achieve a desired level of barrier properties, e.g., one or more, two or more in some embodiments, and two to four layers in some embodiments. Typically, the substrate includes a barrier layer which may include a metal such as aluminum, nickel, tantalum, titanium, or stainless steel. Such a barrier layer is generally impermeable to electrolytes so as to prevent electrolyte leakage, and is also generally impermeable to water and other contaminants. If desired, the substrate may further include an outer layer which serves as a protective layer for the package. In this way, the barrier layer is positioned between the outer layer and the electrode assembly. The outer layer may be formed from a polymer film, such as one formed from polyolefins (e.g., ethylene copolymer, propylene copolymer, propylene homopolymer, etc.), polyester, etc. Particularly preferred polyester films may include, for example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.

[0047] If desired, the substrate may further include an inner layer positioned between the electrode assembly and the barrier layer. In some embodiments, the inner layer may include a heat-sealable polymer. Suitable heat-sealable polymers include, for example, vinyl chloride polymers, vinyl chloridine polymers, ionomers, and combinations thereof. Ionomers are particularly preferred. In one embodiment, for example, the ionomer may be a copolymer comprising α-olefin and (meth)acrylic acid repeating units. Specific α-olefins may include ethylene, propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl, ethyl, or propyl substituents; 1-hexene with one or more methyl, ethyl, or propyl substituents; 1-heptene with one or more methyl, ethyl, or propyl substituents; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Ethylene is particularly preferred. As described above, copolymers may also be (meth)acrylic acid repeating units. As used herein, the term "(meth)acrylic" includes acrylic monomers and methacrylic monomers, as well as their salts or esters, such as acrylate monomers and methacrylate monomers.Examples of such (meth)acrylic monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butyl acrylate, n-amyl acrylate, i-amyl acrylate, isobornyl acrylate, n-hexyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate This may include methacrylate, 2-hydroxyethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, amyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, clotyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, and combinations thereof. Typically, α-olefin / (meth)acrylic acid copolymers are at least partially neutralized with metal ions to form ionomers. Suitable metal ions may include, for example, alkali metals (e.g., lithium, sodium, potassium), alkaline earth metals (e.g., calcium, magnesium), transition metals (e.g., manganese, zinc), and combinations thereof. Metal ions can be provided in the form of ionic compounds such as metal formates, acetates, nitrates, carbonates, bicarbonates, oxides, hydroxides, and alkoxides.

[0048] Within a module, there may be various ways in which ultracapacitors are connected. For example, ultracapacitors may be connected using interconnects that are attached to or connected to each terminal of the ultracapacitors. The interconnects may be made of a conductive material such as a conductive metal. In one embodiment, the interconnect may be relatively flat or may have an increased surface area. With regard to the latter, the interconnect may have protrusions / projections, or may further be formed from wires, braids, coils, etc. In this regard, the specific dimensions and configuration of the interconnect are not necessarily limited. Regardless of its form, any of a variety of different conductive materials may be used, such as copper, tin, nickel, aluminum, and alloys and / or coated metals. If desired, the conductive material may be optionally insulated with a sheath material.

[0049] Ultracapacitors can be electrically connected together in series or in parallel, depending on the desired specific properties. For example, in one particular embodiment, ultracapacitors can be electrically connected in series such that a terminal of a specific polarity (e.g., positive) of one ultracapacitor is connected to a terminal of the opposite polarity (e.g., negative) of another ultracapacitor. For example, the positive terminal may extend from the top of the first ultracapacitor and the negative terminal may extend from the bottom of the second ultracapacitor.

[0050] Ultracapacitors and modules, including those described herein, can be used to store large amounts of electric charge. As a result, the modules and ultracapacitors of this disclosure can be used in a variety of applications. For example, they can be used in a variety of energy applications, including, but not limited to, wind turbines, solar turbines, solar panels, and fuel cells. In addition, they can be used in a variety of transportation applications, including, but not limited to, vehicles (e.g., battery-powered electric vehicles, buses, hybrid electric vehicles including engine starting, power, and brake recovery systems), trains and electric trains (e.g., maglev trains, track switching, starter systems), and aerospace (e.g., door actuators, escape chutes). They also have a variety of industrial applications, including automation (e.g., robotics), vehicles (e.g., forklifts, cranes, electric carts). They also have a variety of applications in consumer electronics (e.g., portable media players, handheld devices, GPS, digital cameras), computers (e.g., laptop computers, PDAs), and communication systems. Modules and ultracapacitors can also have various military applications (e.g., motor starting for tanks and submarines, phased array radar antennas, laser power supplies, radio communications, avionics display and instrumentation, GPS guidance, etc.) and medical applications (e.g., defibrillators, etc.).

[0051] These and other modifications and variations of the present invention may be practiced by those skilled in the art without departing from the spirit and scope of the invention. In addition, it should be understood that the aspects of the various embodiments may be interchangeable, either in whole or in part. Furthermore, those skilled in the art will recognize that the foregoing description is merely an example and is not intended to limit the invention as further described in the appended claims.

Claims

1. Multiple ultracapacitors, The first bus bar, A second busbar is positioned at a distance from the first busbar, A discharge resistor coupled between the first busbar and the second busbar, A first plurality of switching devices, wherein each switching device in the first plurality of switching devices is coupled between the first busbar and the corresponding ultracapacitor among the plurality of ultracapacitors in order to selectively couple the corresponding ultracapacitor to the discharge resistor via the first busbar, A second plurality of switching devices, wherein each switching device in the second plurality of switching devices is coupled between the second busbar and the corresponding ultracapacitor in order to selectively couple the corresponding ultracapacitor to the discharge resistor via the second busbar. Includes, The first plurality of switching devices and the second plurality of switching devices can be configured such that when the first plurality of switching devices and the second plurality of switching devices constitute a first configuration, all of the plurality of ultracapacitors are disconnected from the discharge resistor. One end of one of the plurality of ultracapacitors is configured to be connectable only to a switching device in the first plurality of switching devices or to a switching device in the second plurality of switching devices. Ultracapacitor assembly.

2. The ultracapacitor assembly according to claim 1, wherein when an ultracapacitor among the plurality of ultracapacitors is coupled to the first busbar via a switching device in the first plurality of switching devices, and when the ultracapacitor is further coupled to the second busbar via a switching device in the second plurality of switching devices, the ultracapacitor supplies current to the discharge resistor.

3. The ultracapacitor assembly according to claim 1, wherein when a first ultracapacitor among the plurality of ultracapacitors is coupled to the first busbar via a switching device in the first plurality of switching devices, and a second ultracapacitor among the plurality of ultracapacitors is coupled to the second busbar via a switching device in the second plurality of switching devices, at least the first ultracapacitor and the second ultracapacitor are coupled to the discharge resistor.

4. The ultracapacitor assembly according to claim 3, wherein each of the plurality of ultracapacitors is coupled to the discharge resistor via the first busbar and the second busbar.

5. The ultracapacitor assembly according to claim 1, wherein the total number of switching devices in the first plurality of switching devices and the second plurality of switching devices is greater than the total number of ultracapacitors.

6. The ultracapacitor assembly according to claim 1, wherein the total number of switching devices in the first plurality of switching devices is the same as the total number of switching devices in the second plurality of switching devices.

7. The ultracapacitor assembly according to claim 1, wherein each switching device in the first plurality of switching devices and each switching device in the second plurality of switching devices includes a field-effect transistor.

8. The ultracapacitor assembly according to claim 1, wherein the discharge resistor is coupled between the first busbar and the second busbar via one or more conductors.

9. The ultracapacitor assembly according to claim 1, wherein the second busbar is arranged at an axial distance from the first busbar.

10. The ultracapacitor assembly according to claim 9, wherein the plurality of ultracapacitors are positioned between the first busbar and the second busbar along the axial direction.

11. The ultracapacitor assembly according to claim 10, wherein the plurality of ultracapacitors are arranged spaced apart from each other along the radial direction.

12. Each of the first plurality of switching devices is positioned along the axial direction between the first busbar and the plurality of ultracapacitors. The ultracapacitor assembly according to claim 10, wherein each of the second plurality of switching devices is positioned between the second busbar and the plurality of ultracapacitors along the axial direction.

13. A method for discharging a plurality of ultracapacitors, wherein the method is A step of controlling the operation of a first switching device to couple the plurality of ultracapacitors to a discharge resistor via a first busbar, A step of controlling the operation of a second switching device to couple the plurality of ultracapacitors to the discharge resistor via a second busbar located at a distance from the first busbar, When the plurality of ultracapacitors are coupled to the discharge resistor via the first busbar and the second busbar, the steps include supplying current from the plurality of ultracapacitors to the discharge resistor. Includes, The plurality of first switching devices and the plurality of second switching devices can be configured such that when the plurality of first switching devices and the plurality of second switching devices constitute a first configuration, all of the plurality of ultracapacitors are disconnected from the discharge resistor. A method wherein one end of one of the plurality of ultracapacitors is configured to be connectable only to a switching device in the plurality of first switching devices or to a switching device in the plurality of second switching devices.

14. The step of controlling the operation of the first switching device includes providing one or more control signals related to coupling the ultracapacitor to the discharge resistor via the first busbar, The method according to claim 13, wherein the step of controlling the operation of the second switching device includes the step of providing one or more control signals related to coupling the ultracapacitor to the discharge resistor via the second busbar.

15. The step of controlling the operation of the first switching device includes the step of providing one or more control signals for coupling the first ultracapacitor to the discharge resistor via the first busbar, The method according to claim 13, comprising the step of providing one or more control signals for coupling a second ultracapacitor to the discharge resistor via the second busbar, wherein the second ultracapacitor is coupled in series with the first ultracapacitor.

16. The step of supplying current from the plurality of ultracapacitors to the discharge resistor is The steps include supplying a first current from the first ultracapacitor to the discharge resistor, The steps include supplying a second current from the second ultracapacitor to the discharge resistor, and The method according to claim 15, including the method described in claim 15.

17. The method according to claim 13, wherein the first switching device and the second switching device each include a field-effect transistor.

18. The method according to claim 13, wherein the first busbar and the second busbar are arranged spaced apart along the axial direction.

19. The method according to claim 18, wherein the plurality of ultracapacitors are positioned along the axial direction between the first busbar and the second busbar.

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