Chip-type ultracapacitors

Abstract

To provide an energy storage device suitable for mounting on a printed circuit board using a solder reflow process.SOLUTION: An electric double layer capacitor (chip cap 100) includes a hermetically sealed housing body 101 with positive and negative internal contacts (metal contact pads) and a lid 102. A capacitor including a chip cap storage cell 105 immersed in or wetted by an electrolyte 126 is disposed within the body 101 and the lid 102.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Cross - reference to Related Applications This application is filed under 37 CFR § 1.53(b) and further claims the benefit of previously filed provisional application 62 / 567,752, entitled "Chip Ultracapacitor", filed on October 3, 2017, under 35 USC § 1.119(e), and the entire contents of that application are hereby incorporated by reference herein for any purpose.

[0002] The invention disclosed herein relates to an energy storage device, and more particularly to an ultracapacitor configured to be mounted on an electric circuit board.

Background Art

[0003] Countless devices utilize electronic devices having components disposed on a circuit board. As in all electronic devices, an effective power source is a necessary requirement to supply power to their components. One technique for supplying local power on a circuit board involves the use of energy storage devices such as batteries and capacitors.

[0004] Generally, conventional capacitors supply less than about 360 joules per kilogram of specific energy, while conventional alkaline batteries have a density of about 590 kJ / kg. Ultracapacitors (also called supercapacitors) can charge and discharge much faster than rechargeable batteries and can withstand many more charge - discharge cycles. This makes implementing ultracapacitors an attractive solution for electrical engineers.

[0005] The first design hurdle is that a typical ultracapacitor can be significantly larger than a conventional battery for a given charge. Even with improved power density, another problem lies in the process involved; specifically, the assembly of the electrical circuit requires soldering the components to the circuit board. This "reflow process" generates enough heat to degrade or destroy conventional ultracapacitors. Therefore, while the use of ultracapacitors may be an attractive solution for powering electronic devices mounted on circuit boards, this solution has not been feasible for compact designs requiring high power output. Furthermore, another problem with existing ultracapacitor technology is the limited lifespan of such components. [Overview of the project] [Problems that the invention aims to solve]

[0006] What is needed is an ultracapacitor that helps supply power to electrical components placed on a circuit board. Preferably, the ultracapacitor should offer a compact design suitable for the increasingly smaller size of components, be reflow-resistant, and provide a useful operating life. [Means for solving the problem]

[0007] In one embodiment, an energy storage device suitable for mounting on a printed circuit board using solder reflow is disclosed. In some embodiments, the device includes a sealed housing body (e.g., a lower body fitted with a lid) having positive and negative internal contacts (e.g., metal contact pads), the positive and negative internal contacts being located within the body and electrically communicating with positive and negative external contacts, respectively. Each of the external contacts provides electrical communication to the outside of the body and may be located on the outer surface of the body. An electric double-layer capacitor (EDLC) (also referred to here as an ultracapacitor or supercapacitor) energy storage cell is located in a cavity within a body containing a stack of alternating electrode layers and electrically insulating separator layers. An electrolyte is located in the cavity and moistens the electrode layers. Positive leads electrically connect a first group of one or more electrode layers to the positive internal contacts, and negative leads electrically connect a second group of one or more electrode layers to the negative internal contacts.

[0008] In some embodiments, each electrode layer includes an energy storage medium consisting primarily of a carbonaceous material and substantially free of binders. In some embodiments, the energy storage medium includes a network of carbon nanotubes defining voids and a carbonaceous material (e.g., activated carbon) disposed in the voids and bound together by the network of carbon nanotubes. In some embodiments, at least one electrode layer includes a bifacial electrode layer having an energy storage medium disposed on the opposite side of a conductive current collector layer.

[0009] In some embodiments, the surface of the energy storage cell that is in physical contact with the main body is made of an electrically insulating material (e.g., a layer separator material, or in some embodiments, an insulating envelope barrier placed around the cell).

[0010] In some embodiments, each electrode layer includes a conductive tab attached to either the positive lead or the negative lead. For example, a group of positive electrodes may include tabs connected to the positive lead by, for example, ultrasonic welding or other suitable technique (and similarly for the negative electrode).

[0011] In various embodiments, it is desirable to prevent corrosion and other related harmful effects by insulating electrochemically active parts of the apparatus that may come into contact with the electrolyte during operation. Accordingly, some embodiments include one or more corrosion-preventive functional parts, for example, functional parts located near one of the internal contacts and configured to limit the electrochemical reaction between the internal contact and the electrolyte during operation. In some embodiments, the internal contacts include a first substance having relatively high electrochemical activity with respect to the electrolyte, and the corrosion-preventive functional part includes a protective layer of a second substance having relatively lower electrochemical activity with respect to the electrolyte than the first substance, and the protective layer is arranged to prevent contact between the first substance and the electrolyte. In some embodiments, the protective layer includes, for example, a layer of sealant of the type described herein. In some embodiments, the protective layer includes a metal layer disposed on the surface of the first substance. In some embodiments, the protective layer includes a metal layer disposed on the surface of the first substance and a sealant layer disposed on the metal layer. In some embodiments, the metal layer includes a metal shim fixed or partially fixed by the sealant layer (e.g., to the internal contact). In some embodiments, the inner surface of the body includes a recess configured to receive at least a portion of the corrosion-resistant section. In some embodiments, a portion of the positive or negative electrode lead extends through the corrosion-resistant section and connects to one of the internal contacts. In some embodiments, the corrosion-resistant section includes an aluminum metal layer. In some embodiments, the corrosion-resistant section includes an epoxy sealant.

[0012] Some embodiments include an electrically insulating envelope barrier surrounding the energy storage cell and the electrolyte, configured to prevent contact between the electrolyte and the energy storage cell and the surface of the cavity. In some embodiments, leads extend through the barrier from the energy storage cell to internal contacts. In some embodiments, the barrier is heat-sealed to the die leads to prevent leakage of the electrolyte from within the barrier envelope.

[0013] In some embodiments, the body is a chip (e.g., a ceramic microchip package) configured for surface mounting on a printed circuit board, where, when mounted, the chip extends approximately 5.0 mm, 4.0 mm, 3.5 mm, 3.0 mm, or less above the main surface of the printed circuit board.

[0014] In some embodiments, the device may have an operating voltage of at least 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 3.0V, or higher. In some embodiments, the device may have a capacitance of at least 300mF, 400mF, 450mF, 500mF, or higher. In some embodiments, the device may have an energy density of at least 4.0J / cc, 4.5J / cc, 5.0J / cc, 5.1J / cc, or higher. In some embodiments, the device may have a peak density of at least 15W / cc, at least 20W / cc, at least 22W / cc, or higher. In some embodiments, the device may have an equivalent series resistance of 500mΩ or less, an equivalent series resistance of 400mΩ or less, or an equivalent series resistance of 300mΩ or less. In some embodiments, the device may have operating temperature ratings of at least 65°C, 75°C, 85°C, 100°C, 125°C, 150°C, or higher.

[0015] In some embodiments, the device may have an operating life of at least 2,000 hours at an operating voltage of at least 2.0V (or at least 2.1V or higher) and an operating temperature of at least 65°C, exhibiting capacitance degradation of less than 30% and an equivalent series resistance increase of less than 100%. In some embodiments, the device may have an operating life of at least 1,000 hours, at least 1,500 hours, at least 2,000 hours, at least 3,000 hours, or more at an operating voltage of at least 2.0V (or at least 2.1V or higher) and an operating temperature of 85°C, exhibiting capacitance degradation of at least 30% and an equivalent series resistance increase of less than 100%. In some embodiments, the device may have an operating life of at least 1,000 hours, at least 1,500 hours, at least 2,000 hours, at least 3,000 hours, or more, at an operating voltage of at least 2.0V (or at least 2.1V) and an operating temperature of 100°C, exhibiting capacitance degradation of at least 30% and an equivalent series resistance increase of less than 100%. In some embodiments, the aforementioned operating life occurs after the device is soldered to a printed circuit board using a reflow process having at least 1, 2, 3, 4, 5, 6, or more temperature cycles of at least 30 seconds, 60 seconds, 120 seconds, 180 seconds, 240 seconds, 360 seconds, or more, at a peak temperature of at least 100°C, 200°C, 250°C, 300°C, or more.

[0016] In some embodiments, the energy storage cell provides power (backup power) to at least one additional element mounted on the circuit board (e.g., a solid-state memory device).

[0017] In some embodiments, the electrolyte comprises an ionic liquid, which in some embodiments may be mixed with, for example, the types of salts and / or solvents described herein.

[0018] In some embodiments, the housing body is hermetically sealed. For example, in some embodiments, as described in detail herein, a metal lid may be attached (e.g., welded) to a ceramic element to form the housing body.

[0019] In some examples, the total concentration of halide ions in the cavity of the housing body containing the energy storage cell is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some examples, the concentration of metallic impurities in the cavity of the housing body containing the energy storage cell is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some examples, the concentration of bromoethane, ethyl chloride, 1-bromobutane, 1-chlorobutane, 1-methylimidazole, ethyl acetate, and methylene chloride impurities in the cavity of the housing body containing the energy storage cell is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some embodiments, moisture is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, 100 ppm, 50 ppm, and 10 ppm or less within the cavity of the housing body containing the energy storage cell. In some embodiments, halide impurities are maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, 100 ppm, 50 ppm, and 10 ppm or less within the cavity of the housing body containing the energy storage cell.

[0020] In some embodiments, the device includes a single energy storage cell contained within a sealed housing body, in other words, one energy storage cell per chip. In other embodiments, each chip may include multiple energy storage cells arranged, for example, together in a common cavity, in separate cavities, or in a combination thereof.

[0021] In another embodiment, a method is disclosed for creating an energy storage device suitable for mounting on a printed circuit board using solder reflow. In some embodiments, the method includes forming an electric double-layer capacitor (EDLC) energy storage cell comprising a stack of alternating electrode layers and an electrically insulating separator layer; arranging the energy storage cell having positive and negative internal contacts disposed within the housing body; filling the body at least partially with an electrolyte to moisten the electrode layers; electrically connecting positive leads to the positive internal contacts from a first group of one or more electrode layers; electrically connecting negative leads to the negative internal contacts from a second group of one or more electrode layers; and sealing the housing body having the energy storage cell disposed within the cavity. In some embodiments, sealing the housing body includes hermetically sealing the housing body (e.g., providing low impurity conditions as described herein).

[0022] In another embodiment, a method for providing energy to a device mounted on a printed circuit board is disclosed. In some embodiments, the method may include mounting a device of the type described herein onto a printed circuit board using a solder reflow process, and repeatedly charging and discharging the device at an operating voltage and operating temperature to provide energy to the device. In some embodiments, the operating voltage is at least 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 2.75V, 3.0V, or higher. In some embodiments, the operating temperature is at least 65°C, at least 85°C, at least 100°C, at least 125°C, at least 150°C, or higher. In some embodiments, the method includes repeatedly charging and discharging the device at an operating voltage and operating temperature for at least 2,000 hours while the device exhibits a capacitance degradation of less than 30% and an equivalent series resistance increase of less than 100%.

[0023] Various embodiments may include any of the features and elements described herein, either individually or in any suitable combination.

[0024] The features and advantages of the present invention will be apparent from the following description in connection with the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is a schematic diagram representing an exemplary embodiment of an ultracapacitor. [Figure 2] FIG. 2 is an isometric projection view representing an embodiment of a chip cap according to the teachings herein. [Figure 3] FIG. 3 is an exploded view of the chip cap of FIG. 2 (from an opposing angle). [Figure 4] FIGS. 4A, 4B, and 4C, which are collectively referred to herein as FIG. 4, are explanatory diagrams of electrodes for the chip cap of FIG. 2. [Figure 5] FIG. 5 is a depiction of a stack of energy storage media for use within the energy storage cell of the chip cap of FIG. 2. [Figure 6] FIG. 6 is an isometric projection view representing the energy storage cell of the chip cap of FIG. 2. [Figure 7] FIG. 7 is an isometric projection view representing the body of the chip cap of FIG. 2. [Figure 8] FIG. 8 is a bottom view of the body of FIG. 7. [Figure 9] FIG. 9 is an isometric projection view representing the energy storage cell of FIG. 6 disposed within the body of FIG. 7. [Figure 10] FIG. 10 is a partial schematic cross-sectional view of the body of FIG. 7 in a preparatory state for the incorporation of the energy storage cell. [Figure 11] FIG. 11 is a top-down view of the assembly of FIG. 9. [Figure 12] FIG. 12 is a cross-sectional view of the assembly shown in FIG. 11, the cross-section of which is taken along an axis labeled "A". [Figure 13] FIG. 13 is a graph representing the time-temperature profile for reflow of the chip cap of FIG. 2. [Figure 14]Figures 14-16 are graphs illustrating the performance data for various examples of the tip cap. [Figure 15] Same as above. [Figure 16] Same as above. [Figure 17] Figures 17A to 17B are graphs illustrating the performance data for different examples of the tip cap. [Figure 18] Figures 18A to 18B are graphs illustrating the performance data for different examples of tip caps. [Figure 19] Figure 19 is a schematic diagram showing a system for using the tip cap shown in Figure 2. [Figure 20] Figure 20 is a schematic diagram showing the processing flow for creating the chip cap shown in Figure 2. [Modes for carrying out the invention]

[0026] An energy storage device useful for supplying energy to a circuit board is disclosed herein. Commonly referred to as a "chip cap," this energy storage device is a special type of ultracapacitor configured in a form factor suitable for surface mounting onto a circuit board. Advantageously, the chip cap can withstand the demands associated with the manufacturing and assembly of circuits mounted on the board, and subsequently deliver superior performance compared to existing energy storage devices.

[0027] Before introducing energy storage devices, several terms are provided to explain the background of this teaching.

[0028] Examples of energy storage devices are referred to here as "ultracapacitors," or more specifically, "chipcaps." The term "chipcap" generally refers to examples of ultracapacitors suitable for surface mounting on printed circuit boards (PCBs). Generally, the term "chipcap" is related to conventional microchip components that can be mounted on circuit boards (i.e., chips), and the ultracapacitor technology contained therein.

[0029] As used herein, the term “reflowable” generally refers to the ability of the energy storage devices disclosed herein to withstand the manufacturing process associated with surface mounting to a circuit board. The manufacturing process may include soldering (i.e., reflow) which includes heating cycles that heat the component to a process temperature of 150 degrees Celsius or higher, possibly up to 200 degrees Celsius, and possibly up to 220 degrees Celsius. Such heating cycles may last for periods of 30, 60, 90, 120, 240, 360 seconds, and longer. Thus, as discussed herein, a “reflowable” component is one that can withstand heating cycles suitable for integration into a board-mounted circuit with substantially no future performance degradation. In some embodiments, the components described herein can withstand multiple such reflow cycles, e.g., two, three, four, five, or more such cycles.

[0030] In some embodiments, reflowable components may actually exhibit degraded performance, however, degradation is expected, and the final installation (i.e., assembled or mounted components) may exhibit a predictable performance level that is considered acceptable.

[0031] Before introducing tip caps, several common embodiments of electrochemical double-layer capacitors (EDLCs) are described below in relation to Figure 1. The examples presented herein are not limiting to the art and are provided merely as illustrations for illustrative purposes.

[0032] Figure 1 illustrates a conceptual example of an electrochemical double-layer capacitor (EDLC) 10, also known as an "ultracapacitor." The ultracapacitor 10 includes two electrodes (a negative electrode 3 and a positive electrode 4), each electrode 3, 4 having a double layer of charge at the electrolyte interface. In some embodiments, multiple electrodes are included. However, for the purposes of discussion and illustration, only two electrodes 3, 4 are shown in Figure 1. By convention, each of electrodes 3, 4 uses a carbon-based energy storage medium (as will be discussed further here) to provide energy storage.

[0033] Each of the electrodes 3 and 4 includes its own current collector 2. In the ultracapacitor 10, electrodes 3 and 4 are separated by a separator 5. Generally, the separator 5 is a thin structural material (usually a sheet) used to separate electrodes 3 and 4 into two or more compartments.

[0034] The apparatus contains at least one form of electrolyte 6. The electrolyte 6 fills the spaces within and between electrodes 3, 4 and separator 5. Generally, the electrolyte 6 is a compound that dissociates into charged ions. A solvent for dissolving the compound may be included in some embodiments. The resulting electrolyte conducts electricity through ion transport.

[0035] For convenience, the combination of electrodes 3 and 4, separator 5, and electrolyte 6 is referred to as the "energy storage cell 12". In some embodiments, the term "energy storage cell" simply refers to the separator 5 without electrodes 3 and 4 and electrolyte 6.

[0036] Generally, an exemplary ultracapacitor 10 is packaged within a housing 7 (which may simply be called the “housing 7”), as will be discussed further here. The housing 7 is hermetically sealed. In various examples, the package is hermetically sealed by techniques utilizing laser, ultrasonic, and / or welding techniques. The housing 7 (also called the “case”) includes at least one terminal 8. Each terminal 8 provides electrical access to the energy stored in the energy storage medium 1.

[0037] In an exemplary EDLC 10, the energy storage medium 1 may be provided by or contain activated carbon, carbon fiber, rayon, graphene, aerogel, carbon fiber cloth, and / or carbon nanotubes. An activated carbon electrode can be manufactured, for example, by performing a first activation treatment on a carbon material obtained by carbonizing a carbon compound to produce a carbon substrate, adding a binder to the carbon substrate to produce a molded body, carbonizing this molded body, and finally performing a second activation treatment on the carbonized molded body to produce an activated carbon electrode.

[0038] Carbon fiber electrodes can be produced, for example, using a paper or fabric preform with a high surface area of ​​carbon fiber.

[0039] In one particular example, multi-walled carbon nanotubes (MWNTs) on various substrates using chemical vapor deposition (CVD) are manufactured for use in electrodes 3 and 4. In one embodiment, low-pressure chemical vapor deposition (LPCVD) is used. The manufacturing process may use a mixture of acetylene, argon, and hydrogen gases and an iron catalyst deposited on the substrate using electron beam deposition and / or sputtering deposition.

[0040] In some embodiments, the material used to form the energy storage medium 1 may include materials other than pure carbon. For example, it may include various combinations of materials to provide a binder. However, generally speaking, the energy storage medium 1 is substantially formed from carbon and is therefore called a "carbonaceous material".

[0041] In short, the energy storage medium 1 is mainly formed from carbon, but may also contain any form of carbon and additives or impurities that are deemed appropriate or acceptable to provide the desired functionality as the energy storage medium 1.

[0042] The electrolyte 6 comprises multiple cation 9 and anion 11 pairings, and in some embodiments, may also contain a solvent. Various combinations of each of these may be used. In exemplary EDLC10, cation 11 may include 1-(3-cyanopropyl)-3-methylimidazolium, 1,2-dimethyl-3-propylimidazolium, 1,3-bis(3-cyanopropyl)imidazolium, 1,3-diethoxyimidazolium, 1-butyl-1-methylpiperidinium, 1-butyl-2,3-dimethylimidazolium, 1-butyl-3-methylimidazolium, 1-butyl-4-methylpyridinium, 1-butylpyridinium, 1-decyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 3-methyl-1-propylpyridinium, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, and combinations thereof, as well as other equivalents deemed appropriate.

[0043] In addition, in exemplary EDLC10, anion 9 may include bis(trifluoromethanesulfonate)imide, tris(trifluoromethanesulfonate)methide, dicyanamide, tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonate, bis(pentafluoroethanesulfonate)imide, thiocyanate, trifluoro(trifluoromethyl)borate, spiro-(1,1')-bipyrrolidinium tetrafluoroborate salt, other potential salts such as tetraethylammonium tetrafluoroborate, and combinations thereof, as well as other equivalents deemed appropriate.

[0044] The solvent may include acetonitrile, amides, benzonitrile, butyrolactone, cyclic ethers, dibutyl carbonate, diethyl carbonate, diethyl ether, dimethoxyethane, dimethyl carbonate, dimethylformamide, dimethyl sulfone, dioxane, dioxolane, ethyl formate, ethylene carbonate, ethylmethyl carbonate, lactone, chain ether, methyl formate, methyl propionate, methyltetrahydrofuran, nitrile, nitrobenzene, nitromethane, n-methylpyrrolidone, propylene carbonate, sulforane, sulfone, tetrahydrofuran, tetramethylenesulfone, thiophene, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, carbonate esters, γ-butyrolactone, nitrile, tricyanohexane, butyronitrile, ethylene carbonate, methylenedichloride, and any combination thereof, or other substances exhibiting suitable performance characteristics.

[0045] The separator 5 may be manufactured from nonwoven glass. The separator 5 may also be manufactured from fiberglass, fluoropolymer, Teflon® (PTFE), and ceramics. For example, using nonwoven glass, the separator 5 may include main fibers and binder fibers, each having a smaller fiber diameter, that allow the main fibers to be joined together.

[0046] The above description of the concepts related to the ultracapacitor 10 provides background for the chipcap disclosed and discussed herein.

[0047] In the illustrations of Figures 2 and 3, the tip cap 100 includes a body 101 and a lid 102 mounted thereon. Inside the body 101 and lid 102 is a capacity 103 containing a tip cap energy storage cell 105 immersed in or moistened with an electrolyte 126. The body 101 may also be called part of the housing 7, or the “container” or “package,” or other similar terms. Generally, the tip cap energy storage cell 105 operates according to the principle described above with respect to the ultracapacitor energy storage cell 12. Further embodiments of the tip cap energy storage cell 105 (hereinafter referred to as “energy storage cell 105”) are described below.

[0048] In some embodiments, the body 101 and the lid 102 mounted thereon may have sizes selected for suitability in ultra-miniature electronic technology applications. For example, in some embodiments, the body 101 and the lid mounted thereon are configured for surface mounting on a printed circuit board, where, when surface mounted, the body 101 and lid 102 extend approximately 5.0 mm, 4.0 mm, 3.5 mm, 3.0 mm or less above the main surface of the die-printed circuit board. In some embodiments, the body 101 has a maximum lateral dimension of approximately 5.0 cm, 4.0 cm, 3.0 cm, 2.0 cm, 1.0 cm, 0.5 cm, 0.25 cm or less. In some embodiments, the body 101 is 25.0 cm 2 16.0cm 2 9.0cm 2 , 1.0cm 2 , 0.25cm 2 , 0.1cm 2 , 0.075cm 2 , 0.05cm 2 Or it occupies a horizontal area of ​​less than that.

[0049] In some embodiments, the side surface of the lid 102 facing the interior of the main body 101 may include a corrosion-resistant coating or layer (for example, a polymer or plastic material such as PTFE or polyimide) to prevent unwanted physical or electrical contact between the lid and the energy storage cell 105.

[0050] The process of constructing the tip cap 100 begins with the manufacture of the energy storage cell 105 and the creation of the main body 101.

[0051] The first step in constructing the energy storage cell 105 involves creating electrodes. An example of a double-sided electrode 600 is shown in Figure 4A. Generally, and also as shown in Figure 4A, each double-sided electrode 600 includes a current collector 2 with an energy storage medium 1 located on one side thereof.

[0052] Some embodiments of the electrode include five main components. These components include an aluminum current collector 2, a polymer primer layer (also called the “active material”) provided to facilitate adhesion to the energy storage medium 1, and a three-component active material. The active material may include, for example, activated carbon (to improve capacitance), carbon black (to provide high conductivity and reduce equivalent series resistance (ESR)), and a polymer binder (to bind the powders together).

[0053] In some embodiments, carbon nanotubes (CNTs) are used as substitutes to be provided for the adhesive and binding matrix. That is, the primer may be replaced with a CNT adhesive layer (AL), and the polymer binder for the active substance may also be replaced with CNTs. CNTs may also be used to reduce or replace carbon black as an auxiliary conductive agent. The resulting electrode (i.e., an electrode that does not contain polymers or other adhesives) is "binder-free". Such a binder-free electrode can operate advantageously under extreme conditions (e.g., high pressure and / or high temperature) without degradation due to electrochemical reactions between the binder and the surrounding material (e.g., electrolyte). While we do not wish to be bound by theory, it will be understood that in some embodiments, the electrostatic attraction between carbons in a binder-free electrode (e.g., van der Waals bonds) provides sufficient adhesion and bonding force to maintain the integrity of the electrode even under harsh conditions. For example, in some embodiments, binder-free electrodes may exhibit little to no harmful peeling even when subjected to reflow processing (as detailed herein) or when subjected to operating voltages of at least 2.0V or at least 2.1V or higher at operating temperatures of 65°C, 85°C, 100°C, 125°C, 150°C or higher.

[0054] In some embodiments of binder-free electrodes, the active medium comprises activated carbon (or other types of carbonaceous material) bound by a matrix of carbon nanotubes (CNTs), and the active layer is a matrix of carbon nanotubes (CNTs) without other fillers. Advantageously (for example, to reduce manufacturing costs), in some embodiments, the weight concentration of CNTs in the active layer may be relatively low, and may be less than, for example, 50%, 40%, 30%, 20%, 10%, 7.5%, 5.0%, 2.5%, or less, depending on the desired performance characteristics of the electrode.

[0055] In some embodiments, the matrix is ​​achieved by dispersing activated carbon powder and / or a powder containing carbon nanotubes (CNTs) in isopropyl alcohol using sonication and sufficient energy to unfurl the carbon nanotubes (CNTs) from each other. Successful dispersion can be characterized by material separation and appearance, for example, whether the carbon nanotube (CNT) material separates from the solvent and whether a smooth film appears when dried.

[0056] The bonding and adhesion strength of the active medium and active layer, respectively, are both influenced by the dispersion performance of the carbon nanotubes (CNTs) in their slurries (along with the properties of the carbon nanotubes (CNTs), drying time, layer thickness, substrate material, substrate texture, etc.). The dispersion of carbon nanotubes (CNTs) is influenced by the selection of the solvent (and the properties, concentration, purity of the carbon nanotubes (CNTs), use of surfactants, batch size, dispersion settings, e.g., sonicator amplitude, load cycle, temperature, probe depth, stirring performance, etc.).

[0057] The adhesion of the active medium to the current collector 2 can be improved by adding an adhesive layer (AL) of carbon nanotubes (CNTs) to the current collector 2. This may be done by casting and drying a layer of the active medium on a stainless steel (SS) plate, and using a roll-to-roll apparatus, compressing different plates with vertically aligned carbon nanotubes against the aluminum carbide-coated current collector 2 to transfer the carbon nanotubes (CNTs), and then pressing the plate with the active medium against the current collector 2 / carbon nanotube (CNT) layer to form electrodes.

[0058] In some embodiments, the manufacture of electrodes is carried out by directly casting a thin layer of carbon nanotube (CNT) slurry onto a current collector 2, drying the thin layer, and then casting an active medium slurry on top of it.

[0059] Several techniques may be used to place all the active medium layers on the electrodes. In one embodiment relating to calendering, layers of the active medium are cast onto a stainless steel (SS) plate and dried, then different plates with vertically aligned carbon nanotubes (VACNTs) are compressed against an aluminum carbide-coated current collector 2 using a roll-to-roll apparatus to transfer the vertically aligned carbon nanotubes (VACNTs), and then plates with the active medium are pressed against the aluminum carbide-coated current collector 2 hosting the vertically aligned carbon nanotubes (VACNTs) to form electrodes. In another embodiment, a thin layer of carbon nanotubes (CNTs) is directly cast as a slurry onto the current collector 2 and dried, and then the active medium is cast as a slurry on top of the thin layer of carbon nanotubes (CNTs).

[0060] The selection of activated carbon involves evaluating capacitance versus lifespan. In other words, it was found that in many cases there is a trade-off between the material with the highest capacitance and the material with the longest lifespan. Generally, it was found that the quality of activated carbon should be determined empirically. Regarding the selection of the activated material, carbon nanotube (CNT) powder, it was found that the longer the carbon nanotube (CNT), the stronger the matrix; the lower the wall (layer) in the carbon nanotube (CNT), the better the density efficiency; high purity of the carbon nanotube (CNT) avoids reactive content; and while pores can oxidize and expose the inner surface of the carbon nanotube (CNT), this may result in the addition of impurities. Regarding the selection of the adhesive layer powder, it was found that, in terms of length, carbon nanotube (CNT) that is too long self-adheres too much and peels off from the current collector 2, so bonding strength versus adhesive strength should be evaluated; and thinner layers of CNTs mitigate the risk of peeling off from the current collector 2. Regarding calendering techniques, the carbon nanotube (CNT) matrix may be "activated" by pressurization, and after the CNTs are bonded, it becomes less powdery, and better density can be obtained by increasing the pressure, but the effect diminishes. That is, starting the calendering process (calendering treatment) at low pressure and gradually increasing it with additional passes seems to promote adhesion between layers in some cases. Care should be taken to avoid overuse, as it may lead to delamination. More calender passes can slightly increase density, but will increase the risk of overuse or wrinkling of the current collector 2.

[0061] The adhesive layer may contain carbon nanotubes (CNTs), carbon nanofibers, metal nanowires, and ceramic nanofibers. For the active material, coffee-jointed carbon nanotubes (CNTs) may be used, as well as carbon nanofibers, metal nanowires, and / or ceramic nanofibers. For the energy storage of the active material, activated carbon may be used, and / or other forms of carbon, along with carbon black, additional carbon nanotubes (CNTs), soot, jet black, buckyballs, fullerenes, graphite, graphene, nanohorns, and nanoonions. The carbon nanotubes (CNTs) used may be single-layered, double-layered, or multi-layered, and may be of any length, diameter, purity, crystallinity, or other form as deemed appropriate.

[0062] In various embodiments, the size (dimensions) of the electrodes ranges from approximately 20 μm to approximately 350 μm. In various embodiments, the thickness of the current collector ranges from approximately 10 μm to approximately 50 μm. In various embodiments, the thickness of the adhesive layer ranges from approximately 2 μm to approximately 10 μm or more. The thickness of the active material placed on the adhesive layer may range from approximately 5 μm to approximately 150 μm or more. In some embodiments, the carbon nanotubes (CNTs) used in the adhesive layer have a diameter between 1 nm and approximately 200 nm, a length between approximately 1 μm and approximately 1000 μm, and a wall (layer) count between approximately 1 and 100. In some embodiments, the carbon nanotubes (CNTs) used in the active material have a diameter between 1 nm and approximately 200 nm, a length between approximately 1 μm and approximately 1000 μm, and a wall (layer) count between approximately 1 and 100. In some examples, the active substance comprises roughly spherical particles with a diameter ranging from approximately 2 μm to approximately 30 μm.

[0063] In some embodiments, compression of the energy storage medium is applied after drying. Generally, this facilitates the fixation of carbon nanotubes (CNTs) in place. Roll presses, hydraulic presses, or other types of presses may be used. Care should be taken to avoid damage to the current collectors.

[0064] In various embodiments, the electrode layer may be formed using any of the techniques described in International Patent Application Publication No. WO / 2018 / 102652, published on June 7, 2018, the entire contents of which are incorporated herein by reference.

[0065] Multiple left-handed (Figure 4B) and right-handed (Figure 4C) double-sided electrodes 600 are manufactured to collect current from groups of positive and negative electrodes. Generally, each of the left-handed or right-handed double-sided electrodes 600 includes an energy storage medium 1 located on either side, and also includes a conductive tab 602 where the energy storage medium 1 is substantially absent.

[0066] The electrodes may be punched out from sheet metal using a suitable press. The electrodes punched out from sheet metal will have dimensions suitable for use in the energy storage cell 105. Once electrodes of the appropriate dimensions are cut out, they may be manufactured. Manufacturing electrodes of the appropriate dimensions may include, for example, calendering each electrode to ensure retention of the energy storage medium 1, trimming the edges, and heat treatment to promote the migration and reduction of any impurities. After manufacturing, the electrodes may be moved to a suitable environment in preparation for assembly.

[0067] Once manufactured and suitable for use, the double-sided electrodes 600 are incorporated into a stack assembly. A suitable separator 5 is provided to proceed with the assembly of the stack. The separator 5 may be manufactured from a separator material.

[0068] In some embodiments, separator 5 is cut from a separator material feed, which in one embodiment is a polytetrafluoroethylene (PTFE) feed. PTFE is a synthetic fluoropolymer of tetrafluoroethylene (commonly known as TEFLON®, available from Chemours, Inc. of Delaware). Since PTFE is a polymer compound composed entirely of carbon and fluorine, it is a fluorocarbon solid. In exemplary embodiments, separator 5 is 25 μm thick. An example of an active stack assembly with a single separator 5 is shown in Figure 5.

[0069] Figure 5 illustrates a conceptual aspect of the “z-fold” arrangement of the energy storage medium 1. In the z-fold embodiment, the layers of separator 5 are formed from a single piece of separator material folded in a z-fold manner. The z-fold separator 5 includes opposing positive electrode 4 and negative electrode 3, and an associated current collector 2 folded therein. Generally, as referred to herein, the multilayer assembly of electrodes, current collectors, and separators is called a “stack 201,” and may also be called an “active stack,” or may be referred to by other similar terms.

[0070] To manufacture the z-fold stack 201, the separator 5 is first cut out, and then the first electrode of the double-sided electrode 600 is placed on one end of the separator 5. The separator 5 is then folded, and another opposing double-sided electrode 600 is placed on the separator 5. This process continues until the completed stack 201 is provided. In one embodiment, the completed stack 201 contains 15 double-sided electrodes 600. In this example, the completed stack 201 will have eight (8) layers of negative electrodes and seven (7) layers of positive electrodes. In this embodiment, each double-sided electrode 600 has an area of ​​energy storage material 1 of approximately 6 mm × 8 mm. The exposed portion of the current collector 2, which functions as an integrating tab, has dimensions of approximately 1.5 mm × 8 mm.

[0071] Generally, the stack 201 is configured to provide a desired level of electrical performance. It is not required or necessary that the stack 201 be provided in a z-fold arrangement. In some embodiments, each layer of the stack 201 is separated by individual separators 5. In some embodiments, each layer of the stack 201 may be housed within an envelope of separator material (i.e., surrounded by separator material).

[0072] Similarly, the entire energy storage cell 105 may be provided within an envelope of separator material or other suitable protective barrier (e.g., an electrically insulating thermoplastic material or other suitable material). In some embodiments, this envelope may contain an electrolyte that moistens the stack 201 and prevent the electrolyte from coming into contact with elements outside the barrier. In some such embodiments, a conductive tab 602 may extend outward through the envelope to provide electrical communication between the stack 201 and lead wires (123, 124). Alternatively, in some embodiments, the lead wires (123, 124) may extend through the envelope for connection to the tab 602. Generally, to prevent leakage of electrolyte from the envelope, the envelope may be sealed (e.g., heat-sealed) around such electrical connections.

[0073] In various embodiments, the energy storage cell 105 may be formed using either the technology described in International Patent Application Publication WO2015102716A8, published on November 26, 2015, or International Patent Application Publication WO / 2016057983A3, published on June 30, 2016, the entire contents of which are incorporated herein by reference.

[0074] In some embodiments, the stack 201 is constructed by cutting (e.g., using a blade or cutting laser) or punching out electrode layers from a single electrode material. The electrode material may include thin sheets suitable for use as a current collector 2 having an energy storage material 1 positioned on either side. The alternating layers within the stack 201 constitute the negative and positive electrodes. Separator material is alternately placed between each layer and wrapped around the final assembly to form the completed stack 201.

[0075] Multiple conductive tabs 602 are present, such that the stack 201 contains multilayer electrodes. The multiple conductive tabs 602 extend beyond the energy storage medium 1 to provide electrical contact. In the stack 201, the conductive tabs 602 are grouped by polarity and formed into a single negative lead 123 and a single positive lead 124. As a whole, the assembly of the stack 201 having the negative lead 123 and the positive lead 124 provides an energy storage cell 105. An explanatory diagram of the energy storage cell 105 in assembled form is provided in Figure 6.

[0076] In some embodiments, grouping the conductive tabs 602 onto one of each of the single negative lead 123 and the single positive lead 124 is performed by pre-bending the conductive leads prior to the assembly of the energy storage cell 105. When the energy storage cell 105 is placed within the body 101, the groups of conductive tabs 602 are welded to each pad 110 (Figure 7), thereby forming integrated leads (123, 124). The welding may be performed, for example, by ultrasonic welding or laser welding.

[0077] Figure 7 shows an embodiment of the main body 101. The main body 101 of the tip cap 100 may be manufactured from a dielectric material such as ceramic material in various forms. Inside the main body 101 is an electrical pad 110 for conducting current from a storage cell 105 that has been placed therein. The electrical pad 110 may also conduct current to the storage cell 105 in order to recharge the tip cap 100.

[0078] In the explanatory diagram of Figure 7, the main body 101 generally includes a bottom 111 and four wall portions 112 extending around the bottom 111. Thus, the main body 101 provides a container in which a storage cell 105 can be arranged. The lower side of this example of the main body 101 is shown in Figure 8.

[0079] As shown in Figure 8, the underside of the bottom 111 of the body 101 includes electrical contacts 121 separated by a dielectric 120. At least some of the contacts 121 are electrically connected to the electrical pads 110, enabling energy transfer from the chip cap energy storage cell 105 to the circuit board on which the chip cap 100 may be mounted. Generally, energy is transferred from the electrical pads 110 to the contacts 121 via conductors or vias (not shown) housed within the body 101 and surrounded by the dielectric 121. For example, in some embodiments, the body may house one or more conductive slabs (e.g., embedded within the bottom 110 of the body 101) that establish electrical communication between the electrical pads 110 and the contacts 121. These slabs may be made of, for example, tungsten or other suitable conductive material.

[0080] Accordingly, a conductive passage is formed for each of the double-sided electrodes 600, from the current collector 2 through the conductive tab 602 and each lead (123, 124) to each electrical pad 110, and from the electrical pad 110 through conductive vias in the body 101 to one or more contacts 121 on the bottom surface of the body 101.

[0081] The internal electrical pad 110 is exposed to the cavity 103 (also referred to here as the "void") within the body 101. The lid 102 may contain a compatible material such as ceramic or metallic material. During the assembly of the tip cap 100, the lid 102 is hermetically sealed to the body 101 by being sealed to the seal ring 114. The resulting hermetically sealed seal demonstrates environmental protection by preventing environmental ingress into the tip cap 100, along with leakage of electrolyte from the tip cap 100. The hermetically sealed seal includes any type of seal that makes the tip cap 100 substantially hermetically sealed (blocking the passage of electrolyte, air, oxygen, or other gaseous substances) to ensure proper performance at the intended service interval.

[0082] Examples of equipment suitable for use as main unit 101 include equipment in the surface mount device (SMD) product line commercially available from NTK Technologies in Nagoya, Japan. Other examples are available from Schott AG in Landshut, Germany and Adtech Ceramics Company in Chattanooga, Tennessee, USA.

[0083] In some embodiments, the main body 101 is a high-temperature co-fired ceramic device. Generally, a co-fired ceramic device is a single ceramic microelectronic device in which the entire ceramic support structure and any conductive, resistive, and dielectric materials are fired simultaneously in a kiln.

[0084] Typically, co-fired ceramic devices are manufactured by processing multiple layers independently and then assembling them in a apparatus as a final step. Co-fired firing may be divided into low-temperature (LTCC) and high-temperature (HTCC) applications. Low-temperature devices are manufactured at sintering temperatures below 1,000 degrees Celsius (1,830 degrees Fahrenheit), while high-temperature devices are manufactured at approximately 1,600 degrees Celsius (2,910 degrees Fahrenheit). Compared to LTCC, HTCC has a conductive layer with higher resistance.

[0085] HTCC packages typically consist of a multilayer alumina oxide (Al2O3) with tungsten (W) and morimanganese (MoMn) metal coatings. Advantages of HTCC include mechanical rigidity and airtightness, both of which are important in high-reliability and environmentally stressful applications. Another advantage of HTCC technology is its heat dissipation capability.

[0086] Typical ceramic packages utilize alumina ceramics (Al2O3) in various purities and compositions to support different applications. A typical ceramic package consists of 90-94 percent alumina, with the remainder comprising alkaline earth silicates such as magnesia (MgO) or silica (SiO2), or other adhesives, to control particle size and bond the alumina particles together.

[0087] The main body 101 may be provided as a multilayer ceramic package having a metallized layer that transports power from the energy storage cell 105 to the external contact 121. In the case of high-temperature co-fired ceramics (HTCC), this metallized layer can be made from tungsten (W) or morimanganese (MoMn), or in the case of low-temperature co-fired ceramics (LTCC), it can be made from gold (Au) or copper (Cu).

[0088] Typically, plating is performed across the metallized layer to protect it from oxidation. When metallization treatments such as gold (Au) metallization used in LTCC are employed, additional plating is unnecessary. Generally, the plating layer contains nickel (Ni) as a base, followed by a thin (0.3 μm) layer of gold (Au) for oxidation protection. Alternative plating metals include titanium (Ti) and palladium (Pd). The selected combination of plating metals may relate to the formation of a strong and reliable wire bond.

[0089] In particular, when the energy storage cell 105 is located within the body 101 (Figure 9), the components of the stack 201 (i.e., the current collector 2 and the energy storage medium 1) may be separated from the body 101 (and / or lid 102) by a layer of separator material. This embodiment, called a “separated stack,” provides substantial protection against potential failures of the energy storage cell 105 due to short circuits. In some embodiments, the separated stack is achieved by placing the energy storage cell 105 within an electrically insulating envelope, such as an envelope manufactured from the separator material. Once the energy storage cell 105 has been manufactured, it may be set aside for subsequent installation within the body 101.

[0090] The main body 101 may be manufactured according to desired specifications (such as dimensions, electrical design, environmental constraints, etc.). At least one pocket or well may be added to contain sealant in the area surrounding the electrical pad 110.

[0091] As shown in Figure 10, in some embodiments, the electrical pads 110 are located within each well 205. Each well 205 represents a recess in the upper surface of the bottom 111. Generally, the space provided by each well 205 may be used to fold a portion of each lead wire (123, 124) to maximize the capacity available for the stack 201. The term “well” may be used interchangeably with other terms such as “recess,” “recess,” “pocket,” and other similar terms.

[0092] Each electrical pad 110 may be made of a homogeneous material. For example, the electrical pad 110 may be made of tungsten (W), aluminum (Al), gold (Au), or one of other conductive materials. In some embodiments, the electrical pad 110 is plated with any plating material. The plating layer, or simply the plating 131, may include, for example, gold (Au), nickel (Ni), or copper (Cu). In some further embodiments, the electrical pad 110 is layered. For example, the electrical pad 110 may include a tungsten (W) underlayer along with a nickel (Ni) upper layer. The nickel (Ni) upper layer further has a gold (Au) plating 131.

[0093] Generally, the materials used in the electrical pad 110 and any plating 131 are selected as a balance between conductivity and low reactance in the selected electrolyte 126. Limitation of electrolyte interaction is further achieved by the proper fabrication of the body 101 and the joining of the lead wires (123, 124). At least one sealant may be used as part of such fabrication and joining.

[0094] Gold (Au), nickel (Ni), and tungsten (W) can corrode in the presence of common electrolytes, especially under potential differences. Corrosion resulting from plating or metallization layers will cause premature degradation of the electrolyte and a decrease in the weld joint performance of the tip cap 100. Therefore, a non-reactive sealant may be used to prevent contact between the plating / metallization layer and the electrolyte. As discussed here, the term "non-reactive" refers to a level of reactivity that is generally considered to result in a relative improvement in performance.

[0095] A conductive leader 210 may be joined to each of the electrical pads 110. The joining may be performed, for example, by welding. The welding may be laser welding, ultrasonic welding, or resistance welding. In some other embodiments, conductive epoxy may be used to join the conductive tab 210 to the electrical pad 110. In some embodiments, the conductive leader 210 is formed from aluminum (Al). The configuration of the conductive leader 210 may vary, for example, by the position of each electrode and the configuration of the body 101.

[0096] In one embodiment, the conductive leader 210 is one of the lead wires (123, 124) for the electrode stack 201. In these embodiments, it may be such that only welding is required to join the electrode stack 201 to the body 101. In another embodiment, the conductive leader 210 is an intermediate material initially separate from each lead wire (123, 124) and the electrical pad 110. The conductive leader 210 is then joined to each lead wire (123, 124) after sealant has been applied.

[0097] Once the conductive tab 210 is bonded to the electrical pad 110, sealant may be flowed over the area surrounding the pad 110 and the area around the conductive tab 210. The sealant is then cured. The curing method may include the use of heat, ultraviolet radiation, water / oxygen, evaporation, or other techniques for curing suitable sealant materials.

[0098] In various embodiments, other sealant techniques may be used. For example, in some embodiments, a conformal layer of sealant may be placed in a desired portion of the package. Generally, the conformal layer includes a thin film that "conforms" to the contour of the body 101 to address any imperfections and limit their permeability. The conformal layer may be supplied as a highly viscous, easily flowable component.

[0099] Generally, with respect to any conformal coating method used to passivate the internal electrical pad 110, care is taken to ensure that the conformal coating does not cover external features, seal rings, and other suitable features, as necessary. In some embodiments, the material selected for the conformal coating does not interfere with joining processes (such as welding).

[0100] In one embodiment, the conformal coating comprises a high-temperature thermoplastic polyimide. The high-temperature thermoplastic polyimide may be provided as a substance that exhibits a viscosity slightly higher than water and can be dispensed via a syringe. The resulting insulating layer of the substance has a thickness between about 3–20 μm and exhibits strong bonding with ceramics, aluminum, gold, silicone, and other materials. In some embodiments, the high-temperature thermoplastic polyimide may contain silver or other metal flakes to make the substance conductive. In one embodiment, the high-temperature thermoplastic polyimide is stored at about minus 40 degrees Celsius, operated at ambient temperature, and undergoes a curing cycle at about 150 degrees Celsius for about 10 minutes. The curing cycle will crystallize the high-temperature thermoplastic polyimide, releasing most of the excess material (NMP and H2O) in gaseous form. An additional heating cycle of about 2 minutes and about 250 degrees Celsius may be performed to remove the excess material. The treatment yields a conformal coating with high insulating properties and very low thermal expansion.

[0101] One example of a suitable substance is available from Materion, Inc. in Buffalo, New York, USA, and is sold as Bondflow. Bondflow contains RM1-methyl-2-pyrrolidone (CAS 872-50-4).

[0102] Once the stack 201 is placed inside the main unit 101 and electrically connected to the electrical pad 110, the electrolyte 126 is added to the remaining capacity 103 inside the main unit 101.

[0103] In some embodiments, the electrolyte 126 is a combination of an ionic liquid, an ionic salt, and a solvent. Generally, the ionic liquid and solvent are mixed to achieve a mixture. The mixture may be a completely ionic liquid without a solvent. In some embodiments, the electrolyte is about 20 percent ionic liquid and 80 percent solvent (by volume). A mixture in a partial range may be used.

[0104] Generally, ionic salts may be added to ionic liquids as additional ion storage sources, with different cation and anion sizes, to increase efficiency considering the surface area provided by the electrodes. Ionic salts may be added to mixtures in a range of about 0 M to 2 M (molar concentration, or molar salt / liter solution).

[0105] Next, the body 101 and energy storage cell 105 installed therein may be weighed and filled with an appropriate amount of electrolyte. Filling may be done, for example, using a micropipette. Once filled, the assembly of body 101 and energy storage cell 105 may be placed in a low-pressure environment (i.e., under vacuum). Low pressure facilitates the movement of electrolyte 126 into the energy storage cell 105. Subsequently, the assembly may be weighed again to ensure a stable supply of electrolyte 126. If the assembled body 101, energy storage cell 105 and electrolyte assembly is within the desired parameters, the assembly is sent for welding of the lid 102. The lid 102 may then be welded to the body 101. Welding may be performed in an inert environment, for example, using a seam welding machine.

[0106] In various embodiments, care is taken to avoid unwanted impurities within the cavity 103 housing the energy storage cell 105. In some embodiments, the total concentration of halide ions in the cavity of the housing body containing the energy storage cell is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some embodiments, metallic impurities in the cavity of the housing body containing the energy storage cell are maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some embodiments, impurities of bromoethane, ethyl chloride, 1-bromobutane, 1-chlorobutane, 1-methylimidazole, ethyl acetate, and methylene chloride are maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, and 100 ppm or less. In some embodiments, moisture is maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, 100 ppm, 50 ppm, and 10 ppm or less within the cavity of the housing body containing the energy storage cell. In some embodiments, halide impurities are maintained at approximately 1,000 ppm, 500 ppm, 200 ppm, 100 ppm, 50 ppm, and 10 ppm or less within the cavity of the housing body containing the energy storage cell.

[0107] In various embodiments, the electrolyte may be of any type described in International Patent Application Publication WO2015102716A8, published on 26 November 2015, and International Patent Application Publication WO / 2016204820A2, published on 22 December 2016, the entire contents of which are incorporated herein by reference. For example, in some embodiments, the electrolyte may include a gel or solid electrolyte of the type described in the aforementioned literature.

[0108] Figure 11 provides a top-down view of the assembly in Figure 9. In Figure 11, the energy cell 105 and the main body 101 are divided by a virtual axis - A. Figure 12 is a cropped view of a portion of the energy cell 105 and the main body 101 along the virtual axis - A.

[0109] As shown in Figure 12, the energy storage cell 105 includes a multilayer. Protruding from the multilayer are multiple conductive tabs 602. In this cross section, the multiple conductive tabs 602 are gathered together to provide a negative electrode lead 123 as a whole. During assembly, the negative electrode lead 123 is formed into the appropriate shape and bonded to one of each of the electrical pads 110, and the same process is performed on the positive electrode lead 124 (not shown in this cross section). Subsequently, the body 101 is filled with an embodiment of electrolyte 126 suitable for the tip cap 100. The electrolyte 126 moistens the lead wires (123, 124) and the contents of the energy storage cell 105.

[0110] In some embodiments, the energy storage cell 105 may be a symmetrical EDLC with equal masses of active material on the positive and negative electrodes of the capacitor. However, since the electrodes and electrolyte may not be fully utilized, having equal electrode masses may prevent the EDLC from having its maximum possible specific capacitance when the sizes of anions and cations in the electrolyte are different. In some embodiments, this problem can be solved by balancing the masses by adjusting the electrode masses according to the size of the ions, for example, by increasing the specific capacitance of the EDLC. In some embodiments, the stack 201 may include unequal positive and negative electrode layers to provide improved mass balance.

[0111] The resulting chip cap 100 is typically robust against manufacturing processes that destroy competing equipment. One example of such a manufacturing process is "reflow." In reflow processing, components are heated to a temperature sufficient to produce a flow of solder. Generally, efficient mass production of electronic components requires the use of reflow processes. Furthermore, compact designs often utilize surface mount equipment to limit the space used by components and, similarly, rely on reflow processing.

[0112] In one embodiment, the chip cap 100 is mounted on a printed circuit board according to a recommended solder reflow profile. A graph of time versus temperature is provided in Figure 13. In the example in Figure 13, the temperature is increased at 3 degrees Celsius per second until the preheating phase (called "soaking"). During the preheating phase, the chip cap 100 is maintained at a temperature between approximately 150 and 160 degrees Celsius for approximately 100 seconds. Thereafter, the temperature is increased at 3 degrees Celsius per second until the reflow temperature (called "reflowing"). The reflow temperature can be reached at approximately 260 degrees Celsius. Generally, the time above 200 degrees Celsius should be less than approximately 60 seconds, after which the mounted chip cap 100 is cooled at a rate of approximately 6 degrees Celsius or less.

[0113] In some embodiments, the tip cap 100 may exhibit a capacitance degradation of 10%, 5%, 2.5%, or less in response to one, two, three, four, or more reflow cycles. In some embodiments, the tip cap 100 may exhibit an ESR increase of 10%, 5%, 2.5%, or less in response to one, two, three, four, or more reflow cycles. In some embodiments, the reflow process may essentially act as a seasoning process for the device, advantageously increasing capacitance and / or decreasing the ESR of the tip cap.

[0114] The evaluation of Tip Cap 100 demonstrated excellent performance. To provide some background for the evaluation, we will introduce some terms.

[0115] Electrical circuit theory deals with ideal resistors, capacitors, and inductors, each assumed to simply provide resistance, capacitance, or inductance to the circuit. However, all components have non-zero values ​​for each of these parameters. In particular, all physical devices are composed of materials with finite electrical resistance, and consequently, physical components have some resistance in addition to other properties. The physical cause of ESR depends on the device in question.

[0116] In non-electrolytic capacitors with solid electrolytes and electrolytic capacitors, the metal resistance of the leads and electrodes, as well as the losses in the dielectric, cause ESR. Typical estimated ESR values ​​for ceramic capacitors are 0.01 to 0.1 ohms. The ESR of non-electrolytic capacitors tends to be fairly stable over time; that is, for most purposes, actual non-electrolytic capacitors can be treated as ideal components.

[0117] Aluminum and tantalum electrolytic capacitors with non-solid electrolytes have very high ESR values ​​up to a few ohms. Prior-technical electrolytic capacitors with higher capacitance have lower ESRs. ESR decreases with frequency up to the capacitor's self-resonant frequency. A significant problem, especially with aluminum electrolytes, is that ESR increases over time with use. Even if the measured capacitance remains within tolerance, the ESR can increase to a level sufficient to cause circuit failure and even component damage. While this occurs during normal aging, high temperatures and large ripple currents exacerbate the problem. In circuits with significant ripple currents, the increase in ESR will increase heat dissipation, thereby accelerating aging.

[0118] Electrolytic capacitors that are rated for high-temperature operation and are of higher quality than basic consumer-grade components are less likely to fail prematurely due to increased ESR. Inexpensive electrolytic capacitors may be rated for a lifespan of less than 1000 hours at 85°C. Higher-grade components are typically rated for thousands of hours at their maximum rated temperature. When ESR is critical, certain specifications with higher temperature ratings, "low ESR," or larger capacitance as otherwise required may be advantageous.

[0119] The types of chip caps described here have demonstrated excellent performance under demanding conditions. In some embodiments, the chip caps may have operating voltages of at least 2.0V, 2.1V, 2.2V, 2.3V, 2.4V, 2.5V, 3.0V, or higher. In some embodiments, the chip caps may have capacitances of at least 300mF, 400mF, 450mF, 500mF, or higher. In some embodiments, the chip caps may have energy densities of at least 4.0J / cc, 4.5J / cc, 5.0J / cc, 5.1J / cc, or higher. In some embodiments, the chip caps may have peak power densities of at least 15W / cc, at least 20W / cc, at least 22W / cc, or higher. In some embodiments, the device may have equivalent series resistances of 500mΩ or less, 400mΩ or less, or 300mΩ or less. In some embodiments, the device may have operating temperature ratings of at least 65°C, 75°C, 85°C, 100°C, 125°C, 150°C, or higher. Generally, the aforementioned performance parameters can be achieved using a tip cap housing a single energy storage cell. Extended performance (e.g., high-voltage operation) can be achieved by using multiple tip caps and / or tip caps incorporating multiple energy storage cells.

[0120] In heavy-duty testing, the types of chip caps described herein may demonstrate an operating life of at least 1,000, at least 1,500, at least 2,000 hours, or more, at an operating voltage of at least 2.0V or 2.1V or higher (e.g., 2.5V, 3.0V or higher) and an operating temperature of 65°C, 85°C, 100°C or higher, while exhibiting capacitance degradation of at least 30% and an equivalent series resistance increase of less than 100%. In some embodiments, the aforementioned operating life may be demonstrated after the device has been soldered to a printed circuit board using a reflow process having at least 1, 2, 3, 4, 5, 6, or more temperature cycles of at least 30 seconds, 60 seconds, 120 seconds, 180 seconds, 240 seconds, 360 seconds, or more, at a peak temperature of at least 100°C, 200°C, 300°C, or higher. Advantageously, the aforementioned levels of heavy-duty test performance are expected to correspond to an operating life far exceeding 2,000 hours under non-heavy-duty conditions. For example, in some typical applications (e.g., providing sustained power for solid-state drives in enterprise computer environments), the chip caps may have operating lives of 5,000 hours, 7,500 hours, 10,000 hours, 12,500 hours, or even more, even under conditions requiring thousands, tens of thousands, hundreds of thousands, or millions of charge-discharge cycles.

[0121] Figures 14-16 illustrate the performance characteristics of the tip cap 100 for an embodiment. Figure 14 shows ESR performance data for a sample tip cap operating at 85°C. As shown in the graph, the ESR degradation of the tip cap performance is 98 percent after 3800 hours at this temperature. Comparative data is provided in Figure 15, which shows substantially greater ESR degradation compared to the prior art device. Additional performance data for the tip cap is provided in Figure 16. In Figure 16, the capacitance degradation data at 85°C is only 72% of the initial cell performance after 3800 hours of testing.

[0122] Figures 17A and 17B illustrate the performance characteristics of the chip cap 100 for each embodiment. Figure 17A shows the ESR performance data for a sample chip cap operating at 85°C with a voltage of 2.1V. As shown in the graph, the ESR degradation of the chip cap performance is less than 40 percent after 2,500 hours at this temperature and voltage. Additional performance data for the chip cap is provided in Figure 17B. In Figure 17B, the capacitance degradation data at 85°C with a voltage of 2.1V is less than 14% of the initial cell performance after 2,500 hours of testing. The tests were conducted after successful solder reflow treatment of the chip cap.

[0123] Figures 18A and 18B illustrate the performance characteristics of the chip cap 100 for various embodiments. Figure 18A shows the ESR performance data for a sample chip cap operating at 100°C with a voltage of 2.1V. As shown in the graph, the ESR degradation of the chip cap performance is less than 65 percent after 1,500 hours at this temperature and voltage. Additional performance data for the chip cap is provided in Figure 18B. In Figure 18B, the capacitance degradation data at 100°C with a voltage of 2.1V is less than 14% of the initial cell performance after 1,500 hours of testing. The tests were conducted after successful solder reflow treatment of the chip cap.

[0124] Referring to Figure 19, an example of a computing device 500 that may utilize the chip cap 100 is shown. The computing device 500 may be any one of the following: a personal computer (PC) 501, a laptop 502, a tablet 503, a mobile device (such as a smartphone), and a server 505. Other types of computing devices may also be included. Examples include controllers for automotive systems as well as industrial systems and residential systems (electrical appliances, home electronics, etc.). In short, computing devices utilizing the chip cap 100 may include any electronic device that requires board-level power (e.g., solid-state drives used in enterprise computing). In some embodiments, for example, if the chip has an operating temperature rating of 100°C, 125°C, 150°C or higher, the chip cap may be used in extreme downhole conditions known in the field of oil and gas extraction and production.

[0125] In the diagram shown, the chip cap 100 is used to supply power to the computer memory 501. The storage device 510 may be any type of memory. A power converter and controller suitable for converting the power from the chip cap 100 are not shown here, as such devices are known in the art.

[0126] Referring to Figure 20, a processing flow for assembling the type of chip cap disclosed herein is shown. In step 2001, an electrode roll is provided. The electrode roll may be a double-sided electrode roll having a carbonaceous energy storage medium on the opposite side of a metal foil current collector. In step 2002, a portion of the carbonaceous energy storage medium is removed (e.g., by scraping) to expose the elongated piece of the current collector. In step 2003, left-handed and right-handed electrode layers are punched or cut from the roll, along with conductive tabs formed from the exposed portion of the roll. In step 2004, the punched electrode layers are assembled into separators to form a stack of the type described herein in detail. In step 2005, any excess separators are cut off, and the stack is fixed so that the conductive tabs extend from the stack. In step 2006, the electrode stack is vacuum-dried to remove moisture. In step 2007, the stack is moved into the open body of each package. In step 2008, the stack is electrically connected to the contact pads in the package, as detailed here. In step 2009, the stack is placed inside the package. In step 2010, the electrolyte is dispensed to moisten the electrode layer of the stack. In step 2011, the lid is placed on the package. In step 2012, the lid is welded to the package to form an hermetically sealed seal. In step 2013, the completed tip cap undergoes visual and electrical testing. In step 2014, the tip cap is packaged, for example, by taping and winding the package in a format suitable for pick-and-place installation techniques well known in the art.

[0127] Generally, the term "memory" as used here refers to a computer hardware integrated circuit that stores information for immediate use in a computer, and is synonymous with the term "primary storage device." Computer memory operates at high speed, such as random access memory (RAM), and is distinguished from storage devices that provide high capacity but offer slower access information.

[0128] The terms “storage device,” “primary storage device,” “main memory,” “system memory,” and other similar terms are often associated with addressable semiconductor memory, i.e., integrated circuits containing silicon transistors used not only as primary storage devices but also for other purposes in computers and other digital electronic devices. There are two main types of semiconductor memory: volatile and non-volatile. Examples of non-volatile memory include flash memory (used as secondary storage devices) and ROM, PROM, EPROM, and EEPROM memories (used to store firmware such as BIOS). Examples of volatile memory include primary storage devices, typically dynamic random access memory (DRAM), and fast CPU cache memory, typically static random access memory (SRAM), which is fast but energy-consuming and provides lower storage density than DRAM.

[0129] Volatile memory is a type of computer memory that requires power to maintain the information it stores. Most modern semiconductor volatile memory is either static RAM (SRAM) or dynamic RAM (DRAM). As long as power is connected, SRAM retains its contents. Dynamic RAM is more complex to interface and control and requires regular refresh cycles to prevent data loss.

[0130] Non-volatile memory is computer memory that can retain stored information even when it is not powered. Examples of non-volatile memory include read-only memory (see ROM), flash memory, most types of magnetic computer storage devices (e.g., hard disk drives, floppy disks, and magnetic tapes), optical discs, and early computer storage methods such as paper tape and perforated cards. Near-future non-volatile memory technologies include FeRAM, CBRAM, PRAM, STT-RAM, SONOS, RRAM®, Racetrack memory, NRAM, 3D crosspoint, and millipede memory.

[0131] The third category of memory is "semi-volatile." The term "semi-volatile" generally refers to memory that has a limited non-volatile duration after power is cut off, after which the data is ultimately lost. A typical goal when using semi-volatile memory is to provide some of the advantages of true non-volatile memory, while also offering the high performance, durability, etc., associated with volatile memory.

[0132] A solid-state drive (SSD) is a solid-state storage device that uses an integrated circuit assembly as memory for permanently storing data. SSDs have no moving mechanical parts. This distinguishes SSDs from conventional electromechanical drives such as hard disk drives (HDDs) or floppy disks, which include a rotating disk and a movable read / write head. Compared to electromechanical drives, SSDs are typically more resistant to physical shock, operate quietly, have faster access times, and have lower latency.

[0133] As of 2017, most SSDs use NAND flash memory, a type of non-volatile memory that retains data even when power is lost. For applications that require high-speed access after power loss but do not necessarily require data persistence, SSDs may be composed of random-access memory (RAM). Such devices may use a battery as an integrated power source to retain data for a certain period after the loss of external power.

[0134] However, all SSDs still store data as electrical charge, which slowly leaks over time if left without power. This wears down the storage device (exceeding its endurance rating) and typically leads to the loss of data within it. Therefore, current SSDs are not suitable for archiving purposes.

[0135] Therefore, SSD performance can be substantially improved with the addition of an improved power supply. Many SSDs use capacitors to provide backup power to the DRAM module for writing volatile memory to non-volatile memory. Unfortunately, available capacitors are large and exhibit low performance.

[0136] In short, the SSD environment presents unique challenges not only for ultracapacitor technology but for all capacitive energy storage. Capacitive storage devices are used as built-in electrical energy backups to transfer data stored in volatile memory (SRAM / DRAM) to non-volatile memory (NAND, FLASH®). This operation is crucial in ensuring that data is not lost even in the event of a power grid failure. As computing storage devices become increasingly important for almost all commercial sectors, the need for highly reliable memory backup solutions is a top priority.

[0137] Having thus described embodiments of energy storage devices for supplying power to electrical circuits, several additional embodiments are presented here.

[0138] Various other components may be included and required to provide the aspects of the teachings herein. For example, additional substances, combinations of substances, and / or omissions of substances may be used to provide additional examples within the scope of the teachings herein.

[0139] Various modifications may be made to the teachings herein. Generally, modifications may be designed to meet the needs of users, designers, manufacturers, or other similar stakeholders. Such modifications may be intended to meet specific performance criteria that are considered important by those parties.

[0140] The attached claims or elements of the claims should not be construed to invoke 35 U.S.SC § 112(f) unless the words “means for” or “steps for” are expressly used in a particular claim.

[0141] When describing elements of the present invention or its embodiments, the articles "a," "an," and "the" are intended to indicate that there is one or more of those elements. Similarly, the adjective "another," when used to describe an element, is intended to mean one or more elements. The terms "including" and "having" are intended to be comprehensive, indicating that there may be additional elements other than those described. The term "exemplary" is not intended to mean the best example. Rather, "exemplary" refers to an embodiment that is one of many possible embodiments.

[0142] Although the present invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made without departing from the scope of the invention, and that components can be substituted with equivalents. Furthermore, those skilled in the art will understand that many modifications are made to adapt specific equipment, situations, or substances to the teachings of the invention without departing from the essential scope. Accordingly, the present invention is not limited to the specific embodiments disclosed as the best mode devised for carrying out this invention, but encompasses all embodiments belonging to the appended claims.

Claims

1. An energy storage device suitable for mounting on a printed circuit board using solder reflow processing, A sealed housing body comprising a positive external contact and a negative external contact, respectively, which are arranged within the housing body and are electrically in communication with the positive external contact and the negative external contact, respectively, and each of the external contacts provides electrical communication to the outside of the housing body, An electric double-layer capacitor (EDLC) energy storage cell is disposed within the cavity of the main body and consists of a stack of alternating electrode layers and electrically insulating separator layers. An electrolyte solution is placed inside the cavity to moisten the electrode layer, A positive electrode lead electrically connects one or more of the first groups of electrode layers to the positive electrode internal contact, A negative electrode lead electrically connects one or more second groups of the electrode layers to the negative electrode internal contact, It is an energy storage device equipped with, Each of the electrode layers comprises a substantially binder-free energy storage medium, Each of the energy storage media comprises a carbonaceous material placed in a cavity defined by a network of carbon nanotubes. The housing body is a chip configured for surface mounting on the printed circuit board, and in this case, when mounted in this manner, the chip extends approximately 5.0 mm or less above the main surface of the printed circuit board, in an energy storage device.

2. The apparatus according to claim 1, wherein the chip extends only about 4.0 mm or less above the main surface of the printed circuit board.

3. The apparatus according to claim 1, wherein the chip extends approximately 3.0 mm or less above the main surface of the printed circuit board.

4. The apparatus according to claim 1, having an operating voltage of at least 2.0V.

5. The apparatus according to claim 1, having an operating voltage of at least 3.0V.

6. The apparatus according to claim 1, having a capacitance of at least 300 mF and an energy density of at least 4.0 J / cc.

7. The apparatus according to claim 1, having a capacitance of at least 500 mF.

8. The apparatus according to claim 1, having an energy density of at least 4.0 J / cc.

9. The apparatus according to claim 1, having a peak power density of at least 15 W / cc.

10. The apparatus according to claim 1, having a peak power density of at least 20 W / cc.

11. The apparatus according to claim 1, having an operating life of at least 1,000 hours at an operating voltage of at least 2.0 V and an operating temperature of at least 65 °C.

12. The apparatus according to claim 1, having an operating electrode of at least 2.0 V and an operating temperature of at least 65°C, and having an operating life of at least 2,000 hours.

13. The apparatus according to claim 1, having an operating electrode of at least 2.0 V and an operating temperature of at least 85°C, and having an operating life of at least 2,000 hours.

14. A method for creating an energy storage device suitable for mounting on a printed circuit board using solder reflow processing, To form an electric double-layer capacitor (EDLC) energy storage cell, which includes a stack of alternating electrode layers and electrically insulating separator layers. The energy storage cell is placed within a housing body that includes a positive electrode internal contact and a negative electrode internal contact arranged inside the main body. The main body is filled at least partially with electrolyte to moisten the electrode layer. To electrically connect the positive electrode lead to the positive electrode internal contact from one or more first groups of the electrode layers, The negative electrode lead is electrically connected to the negative electrode internal contact from a second group of one or more electrode layers, wherein each of the electrode layers comprises a substantially binder-free energy storage medium, and each of the energy storage medium comprises a carbonaceous material disposed in a cavity defined by a network of carbon nanotubes. The method involves sealing the housing body in which the energy storage cell is located, and mounting the housing body on the printed circuit board, wherein, when mounted in this manner, the electric double-layer capacitor extends no more than approximately 5.0 mm above the main surface of the printed circuit board. A method for providing this.

15. The method of claim 14, wherein sealing the housing body comprises sealing the housing body airtight.

16. A method for supplying energy to a device mounted on a printed circuit board, Using solder reflow processing, the apparatus described in claim 1 is mounted on the printed circuit board, and The device provides energy to the device by repeatedly charging and discharging the device at an operating voltage and operating temperature. A method wherein the operating voltage is at least 2.0V, and the operating temperature is at least 65°C.

17. The method according to claim 16, further comprising repeatedly charging and discharging the device at operating voltage and operating temperature for at least 2,000 hours while the device exhibits a capacitance degradation of less than 30% and an equivalent series resistance increase of less than 100%, thereby supplying energy to the device.

18. An energy storage device suitable for mounting on a printed circuit board using solder reflow processing, A sealed housing body comprising a positive internal contact and a negative internal contact, each of which is disposed within the sealed housing body and electrically communicates with a positive external contact and a negative external contact, respectively, and each of the external contacts provides electrical communication to the outside of the sealed housing body, An electric double-layer capacitor (EDLC) energy storage cell, disposed within the cavity of the sealed housing body, comprising a stack of alternating electrode layers and electrically insulating separator layers, wherein each of the electrode layers contains a substantially binder-free energy storage medium, and the energy storage medium each contains a carbonaceous material disposed in a cavity bound by a network of carbon nanotubes, and An electrolyte solution is placed inside the cavity to moisten the electrode layer, A positive electrode lead electrically connects one or more of the first groups of electrode layers to the positive electrode internal contact, A negative electrode lead electrically connects one or more second groups of the electrode layers to the negative electrode internal contact, Equipped with, The positive electrode internal contact or the negative electrode internal contact contains a first substance having relatively high electrochemical activity with respect to the electrolyte, and The sealed housing body is a chip configured for surface mounting on the printed circuit board, and in this case, when mounted in this manner, the chip extends approximately 5.0 mm or less above the main surface of the printed circuit board. Energy storage device.

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