Systems and methods for monitoring one or more characteristics of a supercapacitor

Abstract

A method for monitoring one or more characteristics of a supercapacitor is provided. The method includes obtaining a plurality of voltage measurements. Each of the voltage measurements can be obtained at a time interval of a plurality of time intervals in sequence. Further, each of the voltage measurements can be indicative of a voltage across the supercapacitor. The method can include determining an actual voltage step of the supercapacitor based on two consecutive voltage measurements of the plurality of voltage measurements. The method can also include determining whether the actual voltage step exceeds a threshold voltage step of the supercapacitor. Further, in response to determining that the actual voltage step exceeds the threshold voltage, the method can include providing a notification associated with performing a maintenance action on the supercapacitor.

Description

[0001] Priority Statement

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 033,390, filed June 2, 2020, entitled “System and Method for Monitoring One or More Properties of a Supercapacitor,” which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to systems and methods for monitoring one or more characteristics of supercapacitors. Background Technology

[0004] Energy storage units are widely used to supply power to electronic devices, electromechanical devices, electrochemical devices, and other useful equipment. For example, a double-layer supercapacitor can use a pair of polarizable electrodes comprising carbon particles (e.g., activated carbon) impregnated with a liquid electrolyte. Due to the effective surface area of ​​these particles and the small spacing between the electrodes, a large capacitance value can be achieved. Multiple individual double-layer capacitors can be combined to form modules with increased output voltage or increased energy capacity. Summary of the Invention

[0005] One aspect of this disclosure relates to a method for monitoring one or more characteristics of a supercapacitor. The method includes obtaining a plurality of voltage measurements via control circuitry. Each of the plurality of voltage measurements may be obtained sequentially at one of a plurality of time intervals. Furthermore, each of the plurality of voltage measurements may indicate the voltage across the supercapacitor. The method may include determining, via control circuitry, an actual voltage step of the supercapacitor based on two consecutive voltage measurements among the plurality of voltage measurements. The method may further include determining, via control circuitry, whether the actual voltage step exceeds a threshold voltage step of the supercapacitor. Furthermore, in response to determining that the actual voltage step exceeds the threshold voltage step, the method may include providing a notification via control circuitry associated with performing maintenance actions on the supercapacitor.

[0006] Another aspect of this disclosure relates to a system for monitoring one or more characteristics of a supercapacitor. The system includes one or more switching devices configured to selectively couple the supercapacitor to a power source or a load. The system also includes control circuitry communicatively coupled to the one or more switching devices. The control circuitry is configured to acquire a plurality of voltage measurements. Each of the plurality of voltage measurements may be acquired sequentially at one of a plurality of time intervals. Furthermore, each of the plurality of voltage measurements may indicate the voltage across the supercapacitor. The control circuitry is also configured to determine an actual voltage step of the supercapacitor based on two consecutive voltage measurements. The control circuitry is further configured to determine whether the actual voltage step exceeds a threshold voltage step of the supercapacitor. Furthermore, in response to determining that the actual voltage step exceeds the threshold voltage step, the control circuitry is configured to provide a notification associated with performing maintenance actions on the supercapacitor.

[0007] Other features and aspects of this disclosure are set forth in more detail below. Attached Figure Description

[0008] For those skilled in the art, the complete and implementable disclosure (including its best mode) is set forth in more detail in the remainder of the specification with reference to the accompanying drawings, in which:

[0009] Figure 1 A system for monitoring one or more characteristics of a supercapacitor, according to an exemplary embodiment of this disclosure, is described;

[0010] Figure 2 Another system for monitoring one or more characteristics of a supercapacitor, according to an example embodiment of this disclosure, is described.

[0011] Figure 3 A graphical representation of a charge-discharge curve associated with a supercapacitor according to an exemplary embodiment of this disclosure is depicted; and

[0012] Figure 4 A flowchart depicts an example method for monitoring one or more characteristics of a supercapacitor according to an example embodiment of this disclosure.

[0013] Reference numerals used repeatedly in this specification and drawings are intended to indicate the same or similar features or elements in this disclosure. Detailed Implementation

[0014] Those skilled in the art will understand that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this disclosure, which are embodied in the exemplary description.

[0015] The various exemplary aspects of this disclosure relate to systems and related methods for monitoring one or more characteristics of a supercapacitor (e.g., capacitance, equivalent series resistance, ESR, etc.). The system may include control circuitry configured to monitor voltage steps (e.g., changes in the voltage across the supercapacitor with respect to time) to determine one or more characteristics of the supercapacitor. For example, the control circuitry may be configured to acquire a plurality of voltage measurements indicating the voltage across the supercapacitor. Each of these plurality of voltage measurements may be acquired sequentially at one of a plurality of time intervals. For example, in some embodiments, the control circuitry may be configured to acquire a voltage measurement every approximately 2 milliseconds. As used herein, the term "approximately" refers to a value within 10% of the stated value.

[0016] The control circuit can be configured to determine the actual voltage step of the supercapacitor within one of a plurality of time intervals based on two consecutive voltage measurements. For example, the control circuit can obtain a first voltage measurement and a second voltage measurement. The first voltage measurement can indicate the voltage across the supercapacitor at a first time instance. The second voltage measurement can indicate the voltage across the supercapacitor at a second time instance, which occurs after the first time instance has elapsed a time interval corresponding to that time interval. The control circuit can be configured to determine the actual voltage step of the supercapacitor based at least in part on the first and second voltage measurements. For example, the control circuit can be configured to determine the difference between the first and second voltage measurements to determine the actual voltage step of the supercapacitor within a time interval (e.g., the amount of time elapsed between the first and second voltage measurements).

[0017] The control circuit can be configured to determine a threshold voltage step of the supercapacitor. For example, in some embodiments, the control circuit can be configured to determine the threshold voltage step based at least in part on a time interval and the magnitude of the current supplied to the supercapacitor during that time interval. Alternatively or additionally, the threshold voltage step of the supercapacitor can be determined based at least in part on the maximum voltage change across the supercapacitor as a function of current. More specifically, the maximum voltage change as a function of current can be determined based at least in part on the capacitance and the equivalent series resistance (ESR) of the supercapacitor. In some embodiments, the threshold voltage step can be approximately two or three times the maximum voltage change of the supercapacitor as a function of current.

[0018] The control circuit can also be configured to determine whether the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor. For example, the control circuit can be configured to compare the magnitude of the actual voltage step with the magnitude of the threshold voltage step to determine whether the actual voltage step exceeds the threshold voltage step.

[0019] In response to determining that an actual voltage step on the supercapacitor exceeds a threshold voltage step, the control circuitry can be configured to provide electronic communication indicating the need for maintenance actions on the supercapacitor. For example, in some embodiments, this electronic communication may be a text message or email. Alternatively or additionally, the electronic communication may be an audible alarm or notification (e.g., an automated telephone call). In this way, the notification can prompt personnel (e.g., technicians) to repair or replace the supercapacitor.

[0020] In some embodiments, the control circuitry may also be configured to provide one or more control signals associated with controlling the operation of one or more switching devices in response to determining that an actual voltage step of the supercapacitor exceeds a threshold voltage step of the supercapacitor. More specifically, the one or more control signals may be associated with controlling the operation of the one or more switching devices to disconnect the supercapacitor from a power source (e.g., a direct current (DC) power supply). In this way, the supercapacitor may be disconnected from the power source when personnel arrive to perform maintenance actions on the supercapacitor. Additionally, in some embodiments, the one or more control signals may be associated with disconnecting the power source from an electrical load. In this way, the supercapacitor may be disconnected from an electrical load when personnel arrive to perform maintenance actions on the supercapacitor.

[0021] Systems and related methods for monitoring one or more characteristics of a supercapacitor can offer numerous technical effects and benefits. For example, a control circuit can determine one or more characteristics of a supercapacitor, at least in part, based on multiple voltage measurements already received by the control circuit. In this way, the one or more characteristics of the supercapacitor can be determined without requiring any additional hardware. Furthermore, the control circuit can determine one or more characteristics of a supercapacitor without taking the supercapacitor offline (e.g., disconnecting it from the power supply). In this way, one or more characteristics of the supercapacitor can be determined even when the supercapacitor is online (e.g., coupled to a power supply).

[0022] Now refer to the attached diagram, Figure 1A system 100 for monitoring one or more characteristics of a supercapacitor 110 according to an exemplary embodiment of this disclosure is depicted. As shown, the supercapacitor 110 may be coupled between a power source 130 (e.g., DC) and a load 132. In this way, the power source 130 may charge the supercapacitor 110. Furthermore, the supercapacitor 110 may provide (e.g., discharge) current to the load 132.

[0023] As shown in the figure, system 100 may include control circuitry 140. In some embodiments, control circuitry 140 may include processing circuitry (not shown). As used herein, the terms "processor" or "processing circuitry" refer not only to integrated circuits considered to be included in a computer in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and other programmable circuits.

[0024] Control circuit 140 can be configured to acquire a plurality of signals 150 indicating the voltage across supercapacitor 110. Furthermore, control circuit 140 can be configured to determine one or more characteristics of supercapacitor 110 (e.g., capacitance, equivalent series resistance (ESR), etc.) based at least in part on the plurality of signals 150. For example, control circuit 140 can be configured to determine, at least in part, that the capacitance of supercapacitor 110 is decreasing based on the magnitude of the change in voltage across supercapacitor 110 over a time interval between two consecutive voltage measurements. Alternatively, control circuit 140 can be configured to determine, at least in part, that the ESR of supercapacitor 110 is increasing based on the magnitude of the change in voltage across supercapacitor 110 over that time interval. In either case, control circuit 140 can be configured to provide electronic communication to prompt personnel (e.g., technicians) to perform maintenance actions on supercapacitor 110.

[0025] Now for reference Figure 2 This provides another embodiment of system 100 according to an example embodiment of the present disclosure. As shown, system 100 may include a first switching device 120 coupled between supercapacitor 110 and power supply 130 (e.g., direct current (DC) power supply). The first switching device 120 may be configured to be in a first state ( Figure 1In the first state (not shown), the supercapacitor 110 is disconnected from the power supply 130, and in the second state, the supercapacitor 110 is coupled to the power supply 130. When the supercapacitor 110 is coupled to the power supply 130 via the first switching device 120, the supercapacitor 110 can draw power from the power supply 130. In this way, when the first switching device 120 is in the second state, the power supply 130 can charge the supercapacitor 110.

[0026] The system 100 may further include a second switching device 122 coupled between the supercapacitor 110 and the load 132. The second switching device 122 may be configured to be in a first state ( Figure 1 In the first state, the supercapacitor 110 is disconnected from the load 132. In the second state, the supercapacitor 110 is coupled to the load 132 via the second switching device 122. When the second switching device 122 is in the second state, the supercapacitor 110 can supply current to the load 132.

[0027] In some embodiments, the first switching device 120 and the second switching device 122 may include transistors (e.g., field-effect transistors). However, it should be understood that the first switching device 120 and the second switching device 122 may include any suitable device configured to selectively couple the supercapacitor 110 to the power supply 130. It should also be understood that the load 132 drawing power from the power supply 130 may include a suitable load.

[0028] Control circuitry 140 can be communicatively coupled to first switching device 120 and second switching device 122. In this way, control circuitry 140 can provide one or more control signals 160 to first switching device 120 and one or more control signals 162 to second switching device 122. More specifically, the one or more control signals 160 can be associated with controlling the operation of first switching device 120, and the one or more control signals 162 can be associated with controlling the operation of second switching device 122. For example, control circuitry 140 can provide one or more control signals 160 associated with coupling supercapacitor 110 to power supply 130 via first switching device 120 to control the charging of supercapacitor 110. Alternatively, control circuitry can provide one or more control signals 160 associated with disconnecting supercapacitor 110 from power supply 130, and / or one or more control signals 162 associated with coupling supercapacitor 110 to load 132 to control the discharging of supercapacitor 110.

[0029] Figure 3A graphical representation of a charge-discharge curve 200 of a supercapacitor according to an exemplary embodiment of the present disclosure is depicted. More specifically, the change of the supercapacitor's voltage with respect to time is depicted during two charge-discharge cycles. As shown, during the charging cycle, the measured voltage across the supercapacitor increases with respect to time. Conversely, during the discharging cycle, the measured voltage across the supercapacitor decreases with respect to time. Furthermore, whenever the supercapacitor switches between charging and discharging cycles, a voltage step 210 occurs, at least in part due to the supercapacitor's equivalent series resistance (ESR).

[0030] As shown in the figure, the charge-discharge curve 200 may include multiple voltage measurement results 220, which indicate the voltage of the supercapacitor 110 ( Figure 1 and Figure 2 The voltage across the terminals. These multiple voltage measurements 220 can be obtained sequentially at one of a plurality of time intervals 230. For example, each of the multiple voltage measurements can be obtained sequentially at uniform time intervals (e.g., every 2 milliseconds).

[0031] However, it should be understood that the multiple voltage measurements can be obtained at any suitable time interval. For example, in some embodiments, the individual voltage measurements can be obtained sequentially at odd time intervals (e.g., every three milliseconds). It should also be understood that in some embodiments, the duration of each of the multiple time intervals can be the same. For example, each time interval can be approximately 2 milliseconds. As will be discussed in more detail below, the above references Figure 1 and Figure 2 The control circuit 140 in the system 100 under discussion can obtain multiple voltage measurement results 220 to determine whether the voltage step of the supercapacitor 110 at time interval 230 exceeds the threshold voltage step of the supercapacitor 110 at time interval 230, thereby determining one or more characteristics of the supercapacitor 110.

[0032] Figure 4 A flowchart illustrating a method 300 according to an exemplary embodiment of this disclosure is provided. The method 300 may, for example, use... Figure 1 and Figure 2 The system described herein is implemented. For illustrative and discussion purposes, Figure 4 The steps are described in a specific order. Those skilled in the art will understand when using the disclosure provided herein that the steps of any method disclosed herein may be omitted, rearranged, performed concurrently, extended, modified, and / or rewritten in various ways without departing from the scope of this disclosure.

[0033] In (302), method 300 may include: obtaining a plurality of voltage measurements via a control circuit. Specifically, each of the plurality of voltage measurements may be obtained sequentially at one of a plurality of time intervals. Furthermore, each of the plurality of voltage measurements may indicate the voltage across the supercapacitor at a given moment.

[0034] In (304), method 300 may include: determining the actual voltage step of the supercapacitor by means of a control circuit based at least in part on two consecutive voltage measurements of a plurality of voltage measurements obtained in (302). For example, in some embodiments, the control circuit may be configured to determine the actual voltage step based at least in part on a first voltage measurement indicating the voltage across the supercapacitor at a first time instance and a second voltage measurement indicating the voltage across the supercapacitor at a second time instance. More specifically, the control circuit may be configured to determine the difference between the first voltage measurement and the second voltage measurement to determine the actual voltage step of the supercapacitor within a time interval (e.g., the time elapsed between the first voltage measurement and the second voltage measurement).

[0035] In (306), method 300 may include: determining a threshold voltage step of the supercapacitor by means of a control circuit, based at least in part on the capacitance of the supercapacitor and the current supplied to the supercapacitor. In some embodiments, the threshold voltage step may be determined by supplying current to the supercapacitor. In such embodiments, the threshold voltage step may be determined based at least in part on the capacitance of the supercapacitor and the magnitude of the current being supplied to the supercapacitor. More specifically, the maximum voltage change of the supercapacitor when receiving current may be determined based at least in part on the capacitance of the supercapacitor and the ESR of the supercapacitor. In some embodiments, the threshold voltage step may be approximately two or three times the maximum voltage change of the supercapacitor when receiving current.

[0036] In (308), method 300 may include: determining whether the actual voltage step of the supercapacitor, as determined in (304), exceeds the threshold voltage step of the supercapacitor, as determined in (306). For example, control circuitry may be configured to compare the magnitude of the actual voltage step of the supercapacitor with the magnitude of the threshold voltage step of the supercapacitor. If the magnitude of the actual voltage step of the supercapacitor exceeds the magnitude of the threshold voltage step of the supercapacitor, the control circuitry may determine that the capacitance of the supercapacitor is decreasing or the ESR of the supercapacitor is increasing. Furthermore, if the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, the method proceeds to (310). Otherwise, method 300 returns to (302).

[0037] In (310), method 300 may include: in response to determining in (308) that the actual voltage step of the supercapacitor exceeds a threshold voltage step of the supercapacitor, providing electronic communication via one or more processors associated with performing maintenance actions on the supercapacitor. In some embodiments, the electronic communication may include visual notifications (e.g., Short Message Service (SMS) messages, emails, etc.). Alternatively or additionally, the electronic communication may include audible notifications (e.g., audible alarms, automated telephone calls, etc.). In this way, the electronic communication may prompt personnel (e.g., operators) to perform maintenance actions on the supercapacitor. For example, the electronic communication may prompt personnel to repair the supercapacitor. Alternatively, the electronic communication may prompt personnel to replace (i.e., substitute) the supercapacitor with another supercapacitor.

[0038] In (312), method 300 may include providing one or more control signals associated with controlling the operation of one or more switching devices to disconnect the supercapacitor from the power supply. In this way, the supercapacitor may be disconnected from the power supply when personnel arrive to perform maintenance actions on the supercapacitor. Alternatively, in some embodiments, the one or more control signals may be associated with controlling the operation of one or more switching devices to disconnect the supercapacitor from an electrical load. In this way, the supercapacitor may be disconnected from an electrical load when personnel arrive to perform maintenance actions on the supercapacitor.

[0039] According to various exemplary aspects of this disclosure, any of a variety of different individual supercapacitors can typically be employed in a module. However, in some embodiments, the supercapacitor includes an electrode assembly and an electrolyte, which are housed within a housing and optionally hermetically sealed within the housing. The electrode assembly may, for example, include a first electrode and a second electrode, the first electrode including a first carbonaceous coating (e.g., activated carbon particles) electrically coupled to a first current collector, and the second electrode including 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 also be employed if desired, particularly when the supercapacitor comprises multiple energy storage units. These current collectors may be formed of the same or different materials. In any case, each current collector is typically formed from a substrate comprising a conductive metal, such as aluminum, stainless steel, nickel, silver, palladium, etc., and alloys thereof. Aluminum and aluminum alloys are particularly suitable for this disclosure. The substrate may be in the form of foil, sheet, plate, mesh, etc. The substrate may also have a relatively small thickness, for example, about 200 micrometers or less, in some embodiments about 1 micrometer to about 100 micrometers, in some embodiments about 5 micrometers to about 80 micrometers, and in some embodiments about 10 micrometers to about 50 micrometers. Although not required, the surface of the substrate may optionally be roughened, for example by scouring, etching, sandblasting, etc.

[0040] In some embodiments, at least one, and preferably both, of the first and second current collectors may further comprise a plurality of fibrous whiskers projecting outward from the substrate. Without intending to be theoretically limited, it is believed that these whiskers can effectively increase the surface area of ​​the current collector and also 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 and reduce interfacial resistance, and thus produce very low ESR values. The whiskers are typically formed of a material comprising carbon and / or a reaction product of carbon with a conductive metal. In one embodiment, for example, the material may comprise a carbide of a conductive metal, such as aluminum carbide (Al4C3). Typically, the plurality of whiskers project outward from the substrate. If desired, these whiskers may optionally project from a seed portion embedded within the substrate. Similarly, the seed portion may also be formed of a material comprising carbon and / or a reaction product of carbon with a conductive metal, such as a carbide of a conductive metal (e.g., aluminum carbide).

[0041] The method of forming these tendrils on the substrate can vary as needed. In one embodiment, for example, the conductive metal of the substrate is reacted with a hydrocarbon compound. Examples of such hydrocarbon compounds may include, for example, alkane compounds such as methane, ethane, propane, n-butane, isobutane, pentane, etc.; olefin compounds such as ethylene, propylene, butene, butadiene, etc.; alkyne compounds such as acetylene, etc.; and any derivatives or combinations of the aforementioned hydrocarbon compounds. Typically, it is desirable for the hydrocarbon compound to be in a gaseous state during the reaction. Therefore, it may be desirable to use hydrocarbon compounds that are in a gaseous state upon heating, such as methane, ethane, and propane. Although not strictly necessary, hydrocarbon compounds in the range of about 0.1 parts by weight to about 50 parts by weight are typically used based on 100 parts by weight of the substrate, and in some embodiments, hydrocarbon compounds in the range of about 0.5 parts by weight to about 30 parts by weight are used. To initiate the reaction between the hydrocarbon compound and the conductive metal, the substrate is typically heated in an atmosphere at about 300°C or higher. In some embodiments, the substrate is heated in an atmosphere at about 400°C or higher, and in some embodiments, the substrate is heated in an atmosphere at about 500°C to about 650°C. The heating time depends on the exact temperature selected, but typically ranges from about 1 hour to about 100 hours. The atmosphere typically contains a relatively small amount of oxygen to minimize the formation of the dielectric film on the substrate surface. For example, the oxygen content of the atmosphere may be about 1% by volume or less.

[0042] The first carbonaceous coating is also electrically coupled to the first current collector, and the second carbonaceous coating is also electrically coupled to the second current collector. Although the first and second carbonaceous coatings can be formed of the same or different types of materials and can comprise one or more layers, each carbonaceous coating typically comprises at least one layer including activated carbon particles. In some embodiments, for example, the activated carbon layer may be located directly above the current collector and may optionally be the only layer of the carbonaceous coating. Examples of suitable activated carbon particles may include, for example, coconut shell-based activated carbon, petroleum coke-based activated carbon, pitch-based activated carbon, polyvinylidene chloride activated carbon, phenolic resin-based activated carbon, polyacrylonitrile-based activated carbon, and activated carbon from natural sources such as coal, charcoal, or other natural organic sources.

[0043] In some embodiments, it may be desirable to selectively control certain aspects of the activated carbon particles, such as their particle size distribution, surface area, and pore size distribution, to help improve the ion mobility of certain types of electrolytes after one or more charge-discharge cycles. For example, at least 50% by volume of the particles (D50 size) may have a size ranging from about 0.01 micrometers to about 30 micrometers, in some embodiments from about 0.1 micrometers to about 20 micrometers, and in some embodiments from about 0.5 micrometers to about 10 micrometers. Similarly, at least 90% by volume of the particles (D90 size) may have a size ranging from about 2 micrometers to about 40 micrometers, in some embodiments from about 5 micrometers to about 30 micrometers, and in some embodiments from about 6 micrometers to about 15 micrometers. The BET specific surface area may also range from about 900 m². 2 / g (square meter / gram) to approximately 3000m 2 / g, in some embodiments, can be approximately 1000m 2 / g to approximately 2500m 2 / g, and in some embodiments, it can be approximately 1100m 2 / g to approximately 1800m 2 / g.

[0044] In addition to having a certain size and surface area, activated carbon particles may also contain pores with a certain size distribution. For example, the amount of pores smaller than about 2 nanometers (i.e., "micropores") may be about 50 vol% or less of the total pore volume, in some embodiments about 30 vol% or less, and in some embodiments from 0.1 vol% to 15 vol% of the total pore volume. Similarly, the amount of pores between about 2 nanometers and about 50 nanometers (i.e., "mesopores") may be about 20 vol% to about 80 vol%, in some embodiments about 25 vol% to about 75 vol%, and in some embodiments from about 35 vol% to about 65 vol%. Finally, the amount of pores larger than about 50 nanometers (i.e., "macros") may be about 1 vol% to about 50 vol%, in some embodiments about 5 vol% to about 40 vol%, and in some embodiments from about 10 vol% to about 35 vol%. The total pore volume of the activated carbon particles may be about 0.2 cm³. 3 / g (cubic centimeters / gram) to approximately 1.5cm 3 Within the range of / g, and in some embodiments, it can be approximately 0.4cm. 3 / g to approximately 1.0cm3 Within the range of / g; and the median pore width can be approximately 8 nanometers or less, in some embodiments it can be from approximately 1 nanometer to approximately 5 nanometers, and in some embodiments it can be from approximately 2 nanometers to approximately 4 nanometers. The pore size and total pore volume can be measured using nitrogen adsorption, and analyzed using the Barrett-Joyner-Halenda (BJH) technique.

[0045] If desired, the 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, in some embodiments in an amount of 40 parts or less per 100 parts of carbon, and in some embodiments in an amount of about 1 to about 25 parts per 100 parts of carbon. The binder may, for example, comprise about 15% by weight or less of the total weight of the carbonaceous coating, in some embodiments about 10% by weight or less of the total weight of the carbonaceous coating, and in some embodiments about 0.5% by weight to about 5% by weight of the total weight of the carbonaceous coating. Any binder from a variety of suitable binders may be used in the electrode. For example, in some embodiments, water-insoluble organic adhesives may be used, such as styrene-butadiene copolymers, polyvinyl acetate homopolymers, vinyl acetate-ethylene copolymers, vinyl acetate-acrylic copolymers, ethylene-vinyl chloride copolymers, ethylene-vinyl chloride-vinyl acetate terpolymers, acrylic-polyvinyl chloride polymers, acrylic polymers, nitrile polymers, fluoropolymers such as polytetrafluoroethylene or polyvinylidene fluoride, polyolefins, and mixtures thereof. Water-soluble organic adhesives, such as polysaccharides and their derivatives, may also be used. In one particular embodiment, the polysaccharide may be a nonionic cellulose ether, such as alkyl cellulose ethers (e.g., methylcellulose and ethylcellulose), hydroxyalkyl cellulose ethers (e.g., hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylhydroxybutylcellulose, hydroxyethylhydroxypropylcellulose, hydroxyethylhydroxybutylcellulose, hydroxyethylhydroxypropylhydroxybutylcellulose, etc.), alkylhydroxyalkyl cellulose ethers (e.g., methylhydroxyethylcellulose, methylhydroxypropylcellulose, ethylhydroxyethylcellulose, ethylhydroxypropylcellulose, methylethylhydroxyethylcellulose and methylethylhydroxypropylcellulose), carboxyl cellulose ethers (e.g., carboxymethylcellulose), etc., and protonated salts of any of the aforementioned nonionic cellulose ethers, such as sodium carboxymethylcellulose.

[0046] Other materials may also be used within the activated carbon layer 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, conductive additives may be used to further increase conductivity. Exemplary conductive additives may include, for example, carbon black, graphite (natural or synthetic), carbon nanotubes, nanowires or nanotubes, metal fibers, graphene, and mixtures thereof. Carbon black is particularly suitable. When a conductive additive is used, it typically comprises about 60 parts or less per 100 parts of activated carbon particles in the carbonaceous coating, in some embodiments 40 parts or less, and in some embodiments from about 1 part to about 25 parts. The conductive additive may, for example, comprise about 15% by weight or less of the total weight of the carbonaceous coating, in some embodiments about 10% by weight or less, and in some embodiments from about 0.5% by weight to about 5% by weight of the total weight of the carbonaceous coating. Similarly, activated carbon particles typically comprise 85% by weight or more of the carbonaceous coating, in some embodiments about 90% by weight or more of the carbonaceous coating, and in some embodiments from about 95% by weight to about 99.5% by weight of the carbonaceous coating.

[0047] The specific methods by which the carbonaceous coating is applied to the current collector can be varied, such as printing (e.g., rotary gravure printing), spraying, slot coating, drop coating, dip coating, etc. Regardless of the method of application, the resulting electrode is typically dried to remove moisture from the carbonaceous coating, for example, at a temperature of approximately 100°C or higher, in some embodiments at approximately 200°C or higher, and in some embodiments at temperatures from approximately 300°C to approximately 500°C. The electrode can also be compressed (e.g., calendered) to optimize the volumetric efficiency of the supercapacitor. Following any optional compression, the thickness of each carbonaceous coating can typically vary based on the desired electrical performance and desired operating range of the supercapacitor. However, typically, the thickness of the carbonaceous coating is from approximately 20 micrometers to approximately 200 micrometers, from 30 micrometers to approximately 150 micrometers, and in some embodiments, from approximately 40 micrometers to approximately 100 micrometers. The carbonaceous coating can be present on one or both sides of the current collector. In any case, the thickness of the entire electrode (including the current collector and optional compressed one or more carbonaceous coatings) is typically in the range of about 20 micrometers to about 350 micrometers, in some embodiments in the range of about 30 micrometers to about 300 micrometers, and in some embodiments in the range of about 50 micrometers to about 250 micrometers.

[0048] The electrode assembly typically also includes a separator located between the first and second electrodes. Other separators may also be used in the electrode assembly if desired. For example, one or more separators may be located above the first electrode, above the second electrode, or above both the first and second electrodes. The separator provides electrical insulation between the two electrodes to help prevent short circuits, while still allowing ion transport between the two electrodes. In some embodiments, separators may be used, for example, comprising cellulose fiber materials (e.g., cleanroom paper webs, wet-laid paper webs, etc.), nonwoven fiber materials (e.g., polyolefin nonwoven webs), woven fabrics, membranes (e.g., polyolefin membranes), etc. Cellulose fiber materials are particularly suitable for supercapacitors, such as those comprising natural fibers, synthetic fibers, etc. Specific examples of suitable cellulose fibers for the separator may include, for example, hardwood pulp fibers, softwood pulp fibers, rayon fibers, regenerated cellulose fibers, etc. Regardless of the specific material used, the thickness of the diaphragm is typically from about 5 micrometers to about 150 micrometers, in some embodiments from about 10 micrometers to about 100 micrometers, and in some embodiments from about 20 micrometers to about 80 micrometers.

[0049] There are various ways to combine the multiple components of an electrode assembly. For example, electrodes and membranes may initially be folded, rolled, stacked, or otherwise brought together to form an electrode assembly. In one particular embodiment, the electrodes, membrane, and optional electrolyte may be wound into an electrode assembly with a "jelly roll" structure.

[0050] To form a supercapacitor, an electrolyte is placed in ion contact with the first and second electrodes before, during, and / or after the electrodes and separator are assembled to form the electrode assembly. Typically, the electrolyte is inherently non-aqueous and therefore contains at least one non-aqueous solvent. To help extend the operating temperature range of the supercapacitor, it is typically desirable for the non-aqueous solvent to have a relatively high boiling point, for example, about 150°C or higher, in some embodiments about 200°C or higher, and in some embodiments about 220°C to about 300°C. Particularly suitable high-boiling-point solvents may include, for example, cyclic carbonate solvents, such as ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, etc. Of course, other non-aqueous solvents may also be used alone or in combination with cyclic carbonate solvents. Examples of such solvents may include, for example, open-chain carbonates (e.g., dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc.), aliphatic monocarboxylic acid esters (e.g., methyl acetate, methyl propionate, etc.), lactone solvents (e.g., butyrolactone, valerate, etc.), nitriles (e.g., acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, etc.), amides (e.g., N,N-dimethylformamide, N,N-diethylacetamide, N-methylpyrrolidone), alkanes (e.g., nitromethane, nitrobenzene, etc.), sulfur-containing compounds (e.g., sulfolane, dimethyl sulfoxide, etc.); and so on.

[0051] The electrolyte may also comprise at least one ionic liquid dissolved in a non-aqueous solvent. Although the concentration of the ionic liquid can vary widely, it is generally 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 (mol per liter)) or more per liter of electrolyte, in some embodiments in an amount of about 1.0 M or more, in some embodiments in an amount of about 1.2 M or more, and in some embodiments in an amount of about 1.3 M to about 1.8 M.

[0052] Ionic liquids are typically salts with relatively low melting temperatures, for example, about 400°C or lower, in some embodiments about 350°C or lower, in some embodiments from about 1°C to about 100°C, and in some embodiments from about 5°C to about 50°C. The salt contains cationic species and counterions. The cationic species comprises compounds having at least one heteroatom (e.g., nitrogen or phosphorus) as a "cation center". Examples of such heteroatom compounds include unsubstituted or substituted organic quaternary ammonium compounds, such as ammonium (e.g., trimethylammonium, tetraethylammonium, etc.), pyridinium, pyrazineium, pyramidinium, pyrazineium, imidazolineium, pyrazolium, oxazolium, triazolium, thiazolineium, quinolineium, piperidinium, pyrrolidineium, quaternary ammonium spirocyclic compounds (in which two or more rings are linked together by spiro atoms (e.g., carbon, heteroatoms, etc.)), and quaternary ammonium fused ring structures (e.g., quinolineium, isoquinolineium, etc.), etc. In a particular embodiment, for example, the cationic species can be an N-spirobicyclic compound, such as a symmetrical or asymmetric N-spirobicyclic compound having a cyclic ring. An example of such a compound has the following structure:

[0053]

[0054] Wherein, m and n are independently numbers between 3 and 7, and in some embodiments, m and n are independently numbers between 4 and 5 (e.g., pyrrolidineonium or piperidinium).

[0055] Suitable counterions for cationic species may similarly include halogens (e.g., chloride, bromide, iodide, etc.); sulfate or sulfonate groups (e.g., methyl sulfate, ethyl sulfate, butyl sulfate, hexyl sulfate, octyl sulfate, hydrogen sulfate, methanesulfonate, dodecylbenzenesulfonate, dodecyl sulfate, trifluoromethanesulfonate, heptadecafluorooctanesulfonate, sodium dodecyl ethoxysulfate, etc.); sulfosuccinate; amides (e.g., dicyandiamide); imides (e.g., bis(pentafluoroethylsulfonyl)imide, bis(trifluoromethylsulfonyl)imide, bis(trifluoroethylsulfonyl)imide, etc.). Methylimide, etc.; borate (e.g., tetrafluoroborate, tetracyanoborate, bis[oxalate]borate, bis[salicylic acid]borate, etc.); phosphate or phosphonate (e.g., hexafluorophosphate, diethylphosphate, bis(pentafluoroethyl)phosphonate, tri(pentafluoroethyl)-trifluorophosphate, tri(nonafluorobutyl)trifluorophosphate, etc.); antimonate (e.g., hexafluoroantimonate); aluminate (e.g., tetrachloroaluminate); fatty acid carboxylates (e.g., oleate, isostearate, pentadecanoate, etc.); cyanate; acetate; and so on, as well as any combination of the foregoing.

[0056] Several examples of suitable ionic liquids may include, for example, spirocyclic (1,1')-bipyrrolidine tetrafluoroborate, triethylmethyl ammonium tetrafluoroborate, tetraethyl ammonium tetrafluoroborate, spirocyclic (1,1')-bipyrrolidine, methyltriethylammonium iodide, tetraethylammonium iodide, methyltriethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, etc.

[0057] As described above, the supercapacitor also includes a housing, within which the electrode assembly and electrolyte are contained and optionally hermetically sealed. The properties of the housing can be varied as needed. In one embodiment, for example, the housing may comprise a metal container (“can”), such as those formed of tantalum, niobium, aluminum, nickel, hafnium, titanium, copper, silver, steel (e.g., stainless steel), their alloys, their composites (e.g., metals coated with conductive oxides), etc. Aluminum is particularly suitable for this disclosure. The metal container can have any of a variety of different shapes, such as cylindrical, D-shaped, etc. Cylindrical containers are particularly suitable.

[0058] In another embodiment, for example, the housing may take the form of a flexible package surrounding multiple components in the supercapacitor. This package typically includes a substrate extending between two ends and having edges, wherein these ends, along with overlapping portions of the two sides, are fixedly and sealingly abutted against each other (e.g., by thermal welding). In this way, the electrolyte can be retained within the package. The thickness of the substrate typically ranges 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.

[0059] The substrate can contain any number of layers required to achieve the desired level of barrier performance. For example, the substrate can contain one or more layers, in some embodiments two or more layers, and in some embodiments two to four layers. Typically, the substrate contains a barrier layer, which can include metals such as aluminum, nickel, tantalum, titanium, stainless steel, etc. Electrolytes are generally impermeable to this barrier layer, thus preventing electrolyte leakage, and water and other contaminants are also generally impermeable to it. If desired, the substrate can also contain an outer layer serving as a protective layer for the encapsulation. In this way, the barrier layer is located between the outer layer and the electrode assembly. The outer layer can be formed, for example, of a polymer film, such as those formed from polyolefins (e.g., ethylene copolymers, propylene copolymers, propylene homopolymers, etc.), polyesters, etc. Particularly suitable polyester films can include, for example, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.

[0060] If desired, the substrate may also include an inner layer located between the electrode assembly and the barrier layer. In some embodiments, the inner layer may comprise a heat-sealable polymer. Suitable heat-sealable polymers may include, for example, vinyl chloride polymers, vinyl chloramine polymers, ionomers, and combinations thereof. Ionomers are particularly suitable. In one embodiment, for example, the ionomer may be a copolymer containing repeating units of α-olefins and (meth)acrylic acid. Specific α-olefins may include ethylene, propylene, 1-butene; 3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene having one or more methyl, ethyl, or propyl substituents; 1-hexene having one or more methyl, ethyl, or propyl substituents; 1-heptene having one or more methyl, ethyl, or propyl substituents; 1-octene having one or more methyl, ethyl, or propyl substituents; 1-nonene having one or more methyl, ethyl, or propyl substituents; 1-decene substituted with ethyl, methyl, or dimethyl; 1-dodecene; and styrene. Ethylene is particularly suitable. As mentioned above, copolymers can also be repeating units of (meth)acrylic acid. As used herein, the term "(meth)acrylic acid" includes monomers of acrylic and methacrylic acids, as well as their salts or esters, such as monomers of acrylates and methacrylates. Examples of such (meth)acrylate monomers may include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isopentyl 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, 2-hydroxyethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, pentyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl methacrylate, methylcyclohexyl methacrylate, cinnamyl methacrylate, crotonyl methacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate, 2-ethoxyethyl methacrylate, isobornyl methacrylate, etc., and combinations thereof. Typically, α-olefin / (meth)acrylic acid copolymers are at least partially neutralized by metal ions to form ionomers. Suitable metal ions may include, for example, alkali metals (e.g., lithium, sodium, potassium, etc.), alkaline earth metals (e.g., calcium, magnesium, etc.), transition metals (e.g., manganese, zinc, etc.), and combinations thereof. The metal ions may be provided by ionic compounds, such as metal formates, acetates, nitrates, carbonates, bicarbonates, oxides, hydroxides, alkoxides, etc.

[0061] Within the module, the supercapacitors can be connected in various ways. For example, the supercapacitors can be connected using interconnects attached to or connected to the corresponding terminals of the supercapacitor. The interconnects can be made of a conductive material, such as a conductive metal. In one embodiment, the interconnect can be relatively flat, or it can be an interconnect with an increased surface area. Regarding the latter, the interconnect can have protrusions / bulges, or it can be formed from wire, braid, coil, etc. In this respect, the specific size and configuration of the interconnects are not necessarily limited. Regardless of the form of the interconnect, any conductive material from a variety of different conductive materials can be used, such as copper, tin, nickel, aluminum, etc., as well as alloys and / or coated metals. If desired, a sheath material can optionally be used to insulate the conductive material.

[0062] Depending on the desired specific characteristics, multiple supercapacitors can be electrically connected together in series or parallel. For example, in one particular embodiment, multiple supercapacitors can be electrically connected in series such that a terminal of one polarity (e.g., positive) of one supercapacitor is connected to a terminal of the opposite polarity (e.g., negative) of another supercapacitor. For example, the positive terminal may extend from the top of the first supercapacitor, and the negative terminal may extend from the bottom of the second supercapacitor.

[0063] Multiple supercapacitors and modules containing them can be employed to store large amounts of charge. Therefore, the modules and supercapacitors disclosed herein can be used in a wide variety of applications. For example, they can be used in a variety of energy applications, including but not limited to wind turbines, solar generators, solar panels, and fuel cells. Furthermore, they can be used in a variety of transportation applications, including but not limited to vehicles (e.g., battery-powered electric vehicles, hybrid electric vehicles including buses, engine-starting, energy and braking recovery systems, etc.), trains and trams (e.g., maglev trains, track switching, starter systems, etc.), and aerospace (e.g., door actuators, evacuation slides, etc.). They also have a variety of industrial applications, including automation (e.g., robots, etc.), vehicles (e.g., forklifts, cranes, electric trolleys, etc.). They also have various applications in consumer electronics (e.g., portable media players, handheld devices, GPS, digital cameras, etc.), computers (e.g., laptops, personal digital assistants (PDAs), etc.) and communication systems. These modules and supercapacitors can also have a variety of military applications (e.g., electric motor starting for tanks and submarines, phased array radar antennas, laser power supplies, radio communications, avionics displays and instruments, GPS navigation, etc.) and a variety of medical applications (e.g., defibrillators, etc.).

[0064] These and other modifications and variations of the invention can be practiced by those skilled in the art without departing from the spirit and scope of the invention. Furthermore, it should be understood that aspects of the various embodiments can be interchanged, in whole or in part. Moreover, those skilled in the art will understand that the foregoing description is merely exemplary and is not intended to limit the invention further described in the appended claims.

Claims

1. A method for monitoring one or more characteristics of a supercapacitor, the method comprising: Multiple voltage measurement results are obtained through a control circuit. Each of the multiple voltage measurement results is obtained sequentially at one of a plurality of time intervals. Each of the multiple voltage measurement results indicates the voltage across the supercapacitor. The control circuit determines the actual voltage step generated by the supercapacitor when switching between charging and discharging cycles based on two consecutive voltage measurements from the plurality of voltage measurements. The control circuit determines whether the actual voltage step exceeds the threshold voltage step of the supercapacitor when switching between the charging cycle and the discharging cycle. as well as In response to determining that the actual voltage step exceeds the threshold voltage step, the control circuit provides a notification associated with performing maintenance actions on the supercapacitor.

2. The method according to claim 1, further comprising: The control circuit determines the threshold voltage step of the supercapacitor based at least in part on the capacitance of the supercapacitor and the amplitude of the current supplied to the supercapacitor.

3. The method according to claim 2, wherein, Determining the threshold voltage step of the supercapacitor includes: determining the maximum voltage change across the supercapacitor as the current changes, using the control circuit.

4. The method according to claim 3, wherein, The threshold voltage step is approximately twice the maximum voltage change across the supercapacitor.

5. The method according to claim 1, wherein, The duration of each of the plurality of time intervals is the same.

6. The method according to claim 1, wherein, When the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, the capacitance of the supercapacitor is decreasing.

7. The method according to claim 1, wherein, When the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, the equivalent series resistance (ESR) of the supercapacitor is increasing.

8. The method according to claim 1, wherein, Determining whether the actual voltage step exceeds the threshold voltage step includes: determining whether the magnitude of the actual voltage step exceeds the magnitude of the threshold voltage step through the control circuit.

9. The method according to claim 1, wherein, The notification includes electronic communications.

10. The method according to claim 1, wherein, The maintenance action includes replacing the supercapacitor.

11. The method according to claim 1, further comprising: In response to determining that the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, one or more control signals associated with controlling the operation of one or more switching devices are provided by the control circuit to disconnect the supercapacitor from the power supply.

12. A system for monitoring one or more characteristics of a supercapacitor, the system comprising: One or more switching devices, the one or more switching devices being configured to selectively couple the supercapacitor to a power source or a load; as well as A control circuit, communicatively coupled to the one or more switching devices, is configured to: Multiple voltage measurement results are obtained, each of which is obtained sequentially at one of a plurality of time intervals, and each of the multiple voltage measurement results indicates the voltage across the supercapacitor; Based on two consecutive voltage measurement results from the plurality of voltage measurement results, the actual voltage step generated by the supercapacitor when switching between the charging cycle and the discharging cycle is determined; Determine whether the actual voltage step exceeds the threshold voltage step of the supercapacitor when it switches between the charging cycle and the discharging cycle; as well as In response to determining that the actual voltage step exceeds the threshold voltage step, a notification is provided that is associated with performing maintenance actions on the supercapacitor.

13. The system according to claim 12, wherein, The control circuit is further configured to: The threshold voltage step is determined at least in part based on the capacitance of the supercapacitor and the current supplied to the supercapacitor.

14. The system according to claim 12, wherein, The duration of each of the plurality of time intervals is the same.

15. The system according to claim 12, wherein, When the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, the capacitance of the supercapacitor is decreasing.

16. The system according to claim 12, wherein, When the actual voltage step of the supercapacitor exceeds the threshold voltage step of the supercapacitor, the equivalent series resistance (ESR) of the supercapacitor is increasing.

17. The system according to claim 12, wherein, In response to determining that the actual voltage step exceeds the threshold voltage step, the control circuit is further configured to: One or more control signals associated with controlling the operation of the one or more switching devices are provided to disconnect the supercapacitor from the power supply.

18. The system according to claim 12, wherein, The notification includes electronic communications.

19. The system according to claim 12, wherein, The maintenance action includes replacing the supercapacitor.

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