Ultracapacitor

Abstract

Disclosed is a capacitor capable of increasing energy density. According to one aspect, provided is an ultracapacitor comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and an electrolyte, wherein P in Equation 1 is 800 or less. In Equation 1, L is the thickness (µm) of the separator, R is the AC-equivalent series resistance (mΩ) of the ultracapacitor, and F is the capacitance (F) of the ultracapacitor.

Description

ultracapacitor

[0001] The present invention relates to capacitors, and more particularly to ultracapacitors.

[0002] Energy storage devices that store electrical energy include batteries and capacitors. Among these capacitors, ultracapacitors (UC), also known as supercapacitors (SC), possess characteristics intermediate between those of electrolytic capacitors and secondary batteries. Their high efficiency and long lifespan make them a viable next-generation energy storage device for use in conjunction with or as an alternative to secondary batteries.

[0003] Ultracapacitors are also used as a replacement for batteries in applications that require high maintenance requirements and a long service life. Ultracapacitors possess rapid charge and discharge characteristics, making them ideal for auxiliary power sources in mobile communication devices such as cell phones, laptops, and PDAs, as well as in high-capacity applications such as electric vehicles, nighttime road markings, and UPS (Uninterrupted Power Supply). Therefore, they are widely used in these applications.

[0004] Meanwhile, ultracapacitors currently in mass production typically use cellulose-based separators. However, cellulose-based separators are thicker than the polyolefin-based separators commonly used in other energy storage devices (e.g., lithium batteries). This can increase capacitor resistance. Furthermore, the increased thickness of the separator can lead to fewer electrodes being wound, which can lower energy density.

[0005] As the demand for ultracapacitors has diversified recently, the demand for capacitors with high energy density has increased, and many studies are being conducted to increase the energy density of ultracapacitors.

[0006] An object of the present invention is to provide a capacitor having improved energy density.

[0007] The purpose of the present invention is to provide a capacitor that has a high degree of freedom in terms of the configuration of components included in the capacitor when manufacturing the capacitor.

[0008] The purposes of the present invention are not limited to those mentioned above, and other unmentioned purposes and advantages of the present invention can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the purposes and advantages of the present invention can be realized by the means and combinations thereof described in the specification.

[0009] According to one aspect of the present invention for achieving the above object, an ultracapacitor is provided, which includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, and wherein P of the following equation 1 satisfies 800 or less.

[0010] [Formula 1]

[0011] P= L x R x

[0012] In the above equation 1, L is the thickness (㎛) of the separator, R is the AC equivalent series resistance (mΩ) of the ultracapacitor, and F is the capacitance (F) of the ultracapacitor.

[0013] In one embodiment of the present invention, the positive electrode and the negative electrode may include the same or different activated carbon.

[0014] In one embodiment of the present invention, the BET specific surface area of ​​the activated carbon included in the positive electrode is 1,500 to 2,500 m 2 / g, and the BET specific surface area of ​​the activated carbon included in the cathode is 1,500 to 2,500 m 2 / g could be.

[0015] In one embodiment of the present invention, the separation membrane may include a polyolefin resin.

[0016] In one embodiment of the present invention, the thickness of the separation membrane may be 5 to 20 μm.

[0017] In one embodiment of the present invention, the porosity of the separation membrane may be 40 to 70 vol%.

[0018] In one embodiment of the present invention, the capacitance of the ultracapacitor may be 50 to 4,000 F.

[0019] In one embodiment of the present invention, the AC equivalent series resistance of the ultracapacitor may be 4 mΩ or less.

[0020] In one embodiment of the present invention, P in the above formula 1 may be 784 or less.

[0021] The solutions to the above problems are not exhaustive and may be combined with several embodiments of the present disclosure. The various features of the present invention and their corresponding advantages and effects can be understood in more detail by referring to the detailed description below.

[0022] According to one aspect of the present invention, a capacitor with improved energy density can be implemented.

[0023] According to one aspect of the present invention, a capacitor can be provided that has a high degree of freedom in relation to the configuration of components included in the capacitor.

[0024] In addition to the aforementioned effects, specific effects of the present invention are described below along with specific details for implementing the invention. Furthermore, the effects of the present invention are not limited to the effects described above and can be readily achieved using the means and combinations thereof described in the specification.

[0025] FIG. 1 is a drawing showing the configuration of an ultracapacitor according to one embodiment of the present invention.

[0026] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0027] The terms "comprise" and / or "comprising" in this specification specify the presence of stated features, steps, numbers, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, numbers, operations, elements, elements and / or groups thereof.

[0028] If multiple embodiments are described in this specification, the embodiments may be combined unless otherwise specifically stated. In this case, the effects of the present invention may be defined as including the effects derived from each embodiment and the effects resulting from the organic combination of the embodiments. For example, even if Embodiments 1 and 2 are described independently in this specification, Embodiments 1 and 2 may be organically combined with each other unless the context clearly indicates otherwise, and the effects of the present invention may include the effects resulting from the combination of Embodiments 1 and 2.

[0029] The numerical range indicated by the term "to" in this specification refers to a numerical range that includes the values ​​described before and after the term as the lower limit and the upper limit, respectively. When multiple numerical values ​​are disclosed as the upper and lower limits of an arbitrary numerical range, the numerical range disclosed in this specification can be understood as any numerical range that has any one of the multiple lower limit values ​​and any one of the multiple upper limit values ​​as the lower limit and the upper limit, respectively. For example, when a to b, or c to d is described in the specification, it can be understood that a or more and b or less, a or more and d or less, c or more and d or less, or c or more and b or less is described.

[0030] In this specification, an "ultracapacitor" may be an electrical double layer capacitor (EDLC) having an operating principle in which ions contained in an electrolyte are adsorbed or desorbed on an electrode surface; a pseudocapacitor involving a surface chemical reaction; or a hybrid capacitor (hybrid supercapacitor) having the characteristics of these suitably mixed using an asymmetric electrode, and preferably an electrical double layer capacitor.

[0031] In this specification, "AC-equivalent series resistance" refers to a single resistance value of a capacitor that represents all actual losses, and may be any non-ideal resistance connected in series with the capacitor. For example, the AC-equivalent series resistance may be calculated or measured using the following mathematical equations 1 or 2.

[0032] [Mathematical Formula 1]

[0033] R s =(DF) XX c

[0034] In the above mathematical formula 1, R s is the equivalent series resistance (mΩ), DF is the loss factor, and Xc is the capacitive reactance (mΩ).

[0035] [Equation 2]

[0036] P=I 2 XR s

[0037] In the above mathematical expression 2, P is the power loss (watts), I is the current (ampere), and R s is the equivalent series resistance (mΩ).

[0038] According to one aspect of the present invention, an ultracapacitor is provided, comprising: a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte; wherein P of the following equation 1 satisfies 800 or less.

[0039] [Formula 1]

[0040] P= L x R x

[0041] In the above equation 1, L is the thickness (㎛) of the separator, R is the AC equivalent series resistance (mΩ) of the ultracapacitor, and F is the capacitance (F) of the ultracapacitor.

[0042] According to one aspect of the present invention, a capacitor with improved energy density can be implemented by satisfying P of the above formula 1 to be 800 or less.

[0043] Hereinafter, the configuration of the present invention will be described in more detail with reference to the drawings.

[0044] FIG. 1 is a drawing showing the configuration of an ultracapacitor according to one embodiment of the present invention.

[0045] Referring to FIG. 1, an ultracapacitor (100) according to the present invention includes a positive electrode (10), a negative electrode (30), a separator (20), and an electrolyte.

[0046] 1. Ultracapacitor

[0047] anode

[0048] The positive electrode (10) according to the present invention can store electric energy by having ions in the electrolyte move along the electric field and be adsorbed on the surface of the electrode.

[0049] The positive electrode (10) according to the present invention may include a positive electrode current collector and a positive electrode active material layer on at least one surface of the positive electrode current collector. In some examples, the positive electrode active material layer may be disposed on one or both surfaces of the positive electrode current collector.

[0050] The positive electrode current collector according to the present invention can support the positive electrode active material layer to contribute to the structural stability of the positive electrode, and at the same time provide a path for the movement of charges released from or supplied to the positive electrode active material layer.

[0051] In some examples, the positive electrode current collector is not particularly limited and may be copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon; or may be surface-treated with carbon, nickel, silver, etc. on the surface of copper or stainless steel.

[0052] In some examples, the positive electrode current collector may include fine irregularities on its surface. Accordingly, the bonding strength of the positive electrode current collector to the positive electrode active material layer may be enhanced.

[0053] In some examples, the above-described positive electrode collector is not particularly limited and may be transformed into various forms such as a film, sheet, foil, mesh, net, porous structure, foam structure, or non-woven fabric.

[0054] The positive electrode active material layer according to the present invention may include a positive electrode active material, a conductive material, and a binder.

[0055] In some embodiments of the present invention, the positive electrode active material may include activated carbon. Specifically, the activated carbon is an aggregate of amorphous carbon with well-developed micropores manufactured from carbonaceous materials such as brown coal, anthracite coal, and bituminous coal. Through an activation process, micropores on the molecular scale are formed, resulting in a carbon material with a large internal surface area.

[0056] In some embodiments of the present invention, the BET specific surface area of ​​the activated carbon is 1,500 to 2,500 m 2 / g, 1,600 to 2,420 m 2 / g, preferably 1,900 to 2,420 m 2 / g, more preferably 1,600 to 2,000 m 2 / g may be. According to some embodiments of the present invention, by controlling the BET specific surface area of ​​the activated carbon within the above numerical range, the capacitance of the capacitor can be increased, and the charge / discharge speed of the capacitor can be increased.

[0057] In this specification, the average particle diameter of the particles is the particle diameter (D) when the cumulative percentage in the volume-based particle size distribution curve is 50% when measured by a laser diffraction particle size distribution measuring device. 50 ) can be defined. For example, the average particle diameter of the particles can be calculated by dispersing the target particles in a dispersion medium, introducing them into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and measuring the difference in diffraction pattern according to particle size when the particles pass through a laser beam.

[0058] In some embodiments of the present invention, the average particle diameter (D) of the activated carbon 50 ) may be 5 to 20 μm, preferably 5 to 15 μm, and more preferably 5 to 10 μm.

[0059] In some embodiments of the present invention, the content of the activated carbon may be 65 to 95 wt%, preferably 80 to 92 wt%, and more preferably 90 to 92 wt%, based on the total weight of the positive electrode active material layer. Here, the total weight of the positive electrode active material layer may refer to the total solid content of the positive electrode slurry forming the positive electrode active material layer.

[0060] In some embodiments of the present invention, the pore size of the activated carbon may be 0.1 to 500 nm, 0.1 to 100 nm, preferably 1 to 100 nm, and more preferably 50 to 100 nm. For example, the pore size may be measured as a pore diameter analyzed in BJH during BET specificity.

[0061] In some embodiments of the present invention, the average size of the pores included in the activated carbon of the positive electrode may be 0.1 to 500 nm, preferably 1 to 100 nm, and more preferably 50 to 100 mm.

[0062] The conductive material according to the present invention can increase the electrical conductivity of the anode and reduce the resistance of the electrode.

[0063] In some examples, the above-described challenger may be, but is not limited to, specifically Super-P, Ketjen Black, acetylene black, carbon black, or graphite.

[0064] In some embodiments of the present invention, the content of the conductive material may be 3 to 20 wt%, preferably 5 to 10 wt%, based on the total weight of the positive electrode active material layer.

[0065] The binder according to the present invention can provide binding force between positive electrode active materials, between conductive materials, or between positive electrode active materials and conductive materials, and at the same time increase the adhesive force of the positive electrode active material layer to the positive electrode current collector.

[0066] In some embodiments of the present invention, the binder may include at least one selected from the group consisting of carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), methyl cellulose (MC), styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), and polymethyl acrylate (Poly(methyl acrylate)), and specifically, carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber.

[0067] In some embodiments of the present invention, the content of the binder may be 3 to 10 wt%, preferably 3 to 7 wt%, more preferably 4 to 6 wt%, and even more preferably 5 to 6 wt%, based on the total weight of the positive electrode active material layer.

[0068] cathode

[0069] The cathode (30) according to the present invention can store electric energy by having ions in the electrolyte move along the electric field and be adsorbed on the surface of the electrode.

[0070] The negative electrode (30) according to the present invention may include a negative electrode current collector and a negative electrode active material layer on at least one surface of the negative electrode current collector. In some examples, the negative electrode active material layer may be disposed on one or both surfaces of the negative electrode current collector.

[0071] The negative electrode current collector according to the present invention can support the negative electrode active material layer to contribute to the structural stability of the negative electrode, and at the same time provide a path for the movement of charges released from or supplied to the negative electrode active material layer.

[0072] In some examples, the negative current collector may be, but is not particularly limited to, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon; or may be surface-treated with carbon, nickel, silver, or the like on the surface of copper or stainless steel.

[0073] In some examples, the negative electrode current collector may include fine irregularities on its surface. Accordingly, the bonding strength of the negative electrode current collector to the negative electrode active material layer may be enhanced.

[0074] In some examples, the negative electrode current collector may be transformed into various forms such as a film, sheet, foil, mesh, net, porous structure, foam structure, or non-woven fabric.

[0075] The negative electrode active material layer according to the present invention may include a negative electrode active material, a conductive material, and a binder.

[0076] In some embodiments of the present invention, the negative active material may include activated carbon. Specifically, the activated carbon is an aggregate of amorphous carbon with well-developed micropores manufactured from carbonaceous materials such as brown coal, anthracite coal, and bituminous coal, and may be a carbon material having a large internal surface area due to the formation of micropores on the order of molecular size through an activation process. According to some embodiments of the present invention, since the negative active material includes activated carbon, ions in the electrolyte can move along the electric field and be effectively adsorbed on the surface of the activated carbon.

[0077] In some embodiments of the present invention, the BET specific surface area of ​​the activated carbon is 1,500 to 2,500 m 2 / g, preferably 1,900 to 2,420 m 2 / g, more preferably 1,600 to 2,000 m 2 / g may be. According to some embodiments of the present invention, by controlling the BET specific surface area of ​​the activated carbon within the above numerical range, the resistance of the capacitor is lowered as the capacitance of the capacitor is increased, so that not only can the current pass better, but also the charge / discharge speed of the capacitor can be increased.

[0078] In some embodiments of the present invention, the average particle diameter (D) of the activated carbon 50 ) may be 5 to 20 μm, preferably 5 to 15 μm, and more preferably 5 to 10 μm. According to some embodiments of the present invention, by adjusting the average particle diameter of the activated carbon included in the negative electrode within the above numerical range, the capacitance of the capacitor is increased, thereby lowering the resistance of the capacitor and allowing better current passage, and also increasing the charge / discharge speed of the capacitor.

[0079] In some embodiments of the present invention, the content of the activated carbon may be 65 to 95 wt%, preferably 80 to 92 wt%, and more preferably 90 to 92 wt%, based on the total weight of the negative electrode active material layer. Here, the total weight of the negative electrode active material layer may refer to the total solid content of the negative electrode slurry forming the negative electrode active material layer. According to some embodiments of the present invention, by adjusting the content of the activated carbon within the above numerical range based on the total weight of the negative electrode active material layer, more charge can be stored, and thus, the effect of increasing the capacitance of the ultracapacitor can be realized.

[0080] In some embodiments of the present invention, the pore size of the total pore volume of the activated carbon may be 0.1 to 500 nm, preferably 1 to 100 nm, and more preferably 50 to 100 nm. For example, the pore size may be measured as a pore diameter analyzed in BJH during BET specificity.

[0081] In some embodiments of the present invention, the average size of the pores included in the activated carbon of the cathode may be 0.1 to 500 nm, preferably 1 to 100 nm, and more preferably 50 to 100 mm.

[0082] The conductive material according to the present invention can increase the electrical conductivity of the cathode and reduce the resistance of the electrode.

[0083] In some examples, the above-described challenger may be, but is not limited to, specifically Super-P, Ketjen Black, acetylene black, carbon black, or graphite.

[0084] In some embodiments of the present invention, the content of the conductive material may be 3 to 20 wt%, preferably 5 to 10 wt%, based on the total weight of the negative electrode active material layer. In some embodiments of the present invention, by adjusting the content of the conductive material within the above numerical range, the effect of lowering the cell resistance as the resistance of the electrode is lowered can be realized.

[0085] The binder according to the present invention can provide bonding strength between negative electrode active materials, between conductive materials, or between negative electrode active materials and conductive materials, and at the same time increase the adhesive strength of the negative electrode active material layer to the negative electrode current collector.

[0086] In some embodiments of the present invention, the pore size of the total pore volume of the activated carbon may be 0.1 to 500 nm, preferably 1 to 100 nm, and more preferably 50 to 100 nm. For example, the pore size may be measured as a pore diameter analyzed in BJH during BET specificity.

[0087] In some embodiments of the present invention, the average size of the pores included in the activated carbon of the cathode may be 0.1 to 500 nm, preferably 1 to 100 nm, and more preferably 50 to 100 mm.

[0088] The conductive material according to the present invention can increase the electrical conductivity of the cathode and reduce the resistance of the electrode.

[0089] In some examples, the above-described challenger may be, but is not limited to, specifically Super-P, Ketjen Black, acetylene black, carbon black, or graphite.

[0090] In some embodiments of the present invention, the content of the conductive material may be 3 to 20 wt%, preferably 5 to 10 wt%, based on the total weight of the negative electrode active material layer. In some embodiments of the present invention, by adjusting the content of the conductive material within the above numerical range, the effect of lowering the cell resistance as the resistance of the electrode is lowered can be realized.

[0091] The binder according to the present invention can provide bonding strength between negative electrode active materials, between conductive materials, or between negative electrode active materials and conductive materials, and at the same time increase the adhesive strength of the negative electrode active material layer to the negative electrode current collector.

[0092] membrane

[0093] The separator (20) according to the present invention can facilitate the movement of ions in an electrolyte and electrically separate the positive and negative electrodes.

[0094] The separator (20) according to the present invention is interposed between the anode (10) and the cathode (30).

[0095] In some embodiments of the present invention, the separator may include a polyolefin resin. Specifically, the polyolefin resin may include any one selected from the group consisting of polyethylene, polypropylene, and mixtures thereof.

[0096] In some embodiments of the present invention, the weight average molecular weight (Mw) of the polyolefin may be 300,000 to 1,000,000 g / mol, or 400,000 to 800,000 g / mol, and preferably 600,000 to 700,000 g / mol.

[0097] Meanwhile, ultracapacitors currently in mass production typically use cellulose-based separators. However, cellulose-based separators are thicker than the polyolefin-based separators commonly used in other energy storage devices (e.g., lithium batteries). This can increase capacitor resistance. Furthermore, the increased thickness of the separator can lead to fewer electrodes being wound, which can lower energy density.

[0098] As the demand for ultracapacitors has diversified recently, the demand for capacitors with high energy density has increased, and many studies are being conducted to increase the energy density of ultracapacitors.

[0099] Meanwhile, the ultracapacitor of the present invention is characterized by using a polyolefin-based separator rather than a conventionally used cellulose-based separator.

[0100] The inventors of the present invention have confirmed that when a polyolefin-based separator is used in a system that satisfies certain conditions instead of a cellulose-based separator, the energy density can be increased while maintaining the excellent characteristics of the capacitor, and even the degree of freedom in the configuration of capacitor components can be secured.

[0101] In particular, by using a polyolefin separator instead of a relatively thick cellulose separator, a larger amount of electrodes can be wound within the capacitor to increase the energy density, and even without further winding of electrodes to increase the energy density, room can be secured to include various elements within the capacitor, thereby increasing the degree of freedom in capacitor manufacturing.

[0102] In some embodiments of the present invention, the thickness of the separation membrane may be 5 to 20 μm, 9 to 16 μm, 9 to 12 μm, or 12 to 16 μm.

[0103] According to some embodiments of the present invention, the thickness of the separator is controlled within the above numerical range, thereby making the thickness thinner compared to existing cellulose-based separators, thereby increasing the energy density of the capacitor.

[0104] In some embodiments of the present invention, the porosity of the separation membrane may be 40 to 70 vol%, or 40 to 60 vol%, and specifically 42 to 49 vol%, based on the total pore volume of the separation membrane. According to some embodiments of the present invention, the porosity of the separation membrane

[0105] In some embodiments of the present invention, the Gurley permeability of the membrane may be 50 to 400 s / 100 ml, 75 to 209 s / 100 ml, or 200 to 300 s / 100 ml.

[0106] electrolyte

[0107] The electrolyte according to the present invention can provide electrolyte ions (salts) that are adsorbed or desorbed from a positive electrode active material or a negative electrode active material.

[0108] The electrolyte according to the present invention may include a solvent and a salt. In this case, when voltage is applied to each electrode, the cations and anions contained in the salt may be attracted to the electrode with the opposite charge, thereby forming a double layer of charge.

[0109] In some embodiments of the present invention, the solvent may include at least one selected from the group consisting of acetonitrile, propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, gamma-butyrolactone, sulfolane, dimethyl sulfoxide, and tetrahydrofuran.

[0110] In some embodiments of the present invention, the salt may include a quaternary ammonium salt. According to some embodiments of the present invention, by using a quaternary ammonium salt as the salt, the solubility of the salt in the electrolyte can be increased, thereby increasing the overall capacity of the capacitor, and the internal resistance of the capacitor can be lowered, thereby improving the energy efficiency of the capacitor.

[0111] In some examples, the cation of the salt may be any one selected from the group consisting of tetraethyl ammonium, triethylmethyl ammonium, trimethylethyl ammonium, ammonium having a 1,1-dialkyl heteromonocyclic compound, and ammonium-spirobicyclic compounds, and the anion of the salt may be hexafluorophosphate or tetrafluoroborate.

[0112] In some embodiments of the present invention, the concentration of the quaternary ammonium salt may be 0.5 to 2.0 M, preferably 0.7 to 1.4 M.

[0113] Meanwhile, unlike cellulose separators, polyolefin-based separators have low electrolyte wettability, and thus an additional pressure impregnation step can be performed after the electrolyte is injected. In some embodiments of the present invention, after the electrolyte is injected into the capacitor, the capacitor may be pressurized at a pressure of 0.1 to 10 bar, 0.1 to 8 bar, or 0.1 to 5 bar for a time period of 1 second to 3 hours, 2 seconds to 2 hours, 3 seconds to 1 hour, or 5 seconds to 30 minutes.

[0114] Properties of capacitors

[0115] Meanwhile, capacitance refers to the ability of a capacitor to store charge.

[0116] In some embodiments of the present invention, the capacitance of the ultracapacitor may be 50F or more, 100F or more, or 1,500F or more; 4,000F or less, 3,000F or less, 2,000F or less, or 1,500F or less; or any one of the plurality of lower limits and any one of the plurality of upper limits. For example, the capacitance may be 50 to 4,000F, 100 to 1,500F, or 1,500 to 4,000F.

[0117] In some embodiments of the present invention, the AC equivalent series resistance of the ultracapacitor may be 4 mΩ or less, 3.3 mΩ or less, 2 mΩ or less, 1.8 mΩ or less, 0.3 mΩ or less, or 0.2 mΩ or less, and specifically, may be 0.05 mΩ or less.

[0118] Meanwhile, according to one aspect of the present invention, an ultracapacitor is provided, which includes a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte; and wherein P of the following equation 1 satisfies 800 or less.

[0119] [Formula 1]

[0120] P= L x R x

[0121] In the above equation 1, L is the thickness (㎛) of the separator, R is the AC equivalent series resistance (mΩ) of the ultracapacitor, and F is the capacitance (F) of the ultracapacitor. According to one aspect of the present invention, when P of the above equation 1 satisfies 800 or less, a capacitor with improved energy density can be implemented. If P of the above equation 1 exceeds 800, the energy density may not be effectively improved.

[0122] In some embodiments of the present invention, P of the above formula 1 may be 784 or less, 600 or less, 599 or less, 588 or less, 528 or less, 449 or less, 441 or less, 396 or less, 337 or less, or 297 or less, and specifically may be 200 to any one of the multiple upper limits. According to some embodiments of the present invention, excellent capacity retention can be realized as P of the above formula 1 satisfies the numerical range.

[0123] When a polyolefin-based separator is used in a system satisfying the conditions of the above equation 1, the energy density can be increased while maintaining the excellent characteristics of the capacitor, and the degree of freedom in the configuration of the capacitor components can be secured.

[0124] In some embodiments of the present invention, the capacity retention of the ultracapacitor measured after the cell has been left at 75° C. for 288 hours may be 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, or 92% or more.

[0125] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following contents.

[0126] As used herein, terms such as "about" or "substantially" refer to a reasonable amount of variation from the term that does not significantly alter the final result. These terms may be interpreted to include a variation of at least ±5% or at least ±10%, provided that such variation does not alter the meaning of the term and render it invalid.

[0127] [Manufacturing Preparation Example: Preparation of Membrane]

[0128] Separators according to Comparative Preparation Examples 1 and 2 and Implementation Preparation Examples 1 to 3, each having the properties shown in Table 1 below, were prepared.

[0129] Porosity measurement method:

[0130] The porosity of a membrane refers to the ratio of the volume occupied by pores to the total volume of the membrane. Specifically, the porosity (vol %) of the membranes according to Preparation Examples 1 to 3 was measured in accordance with ISO 1014: 2021.

[0131] Method for measuring permeability:

[0132] The Gurley permeability of the membrane was measured using a permeability measuring device (Toyoseiki Densometer). Here, the Gurley permeability is defined as the permeability of 1.0 in (100 ml) of air under a pressure of 567 g (1.21 kPa) in accordance with the Japanese Industry Standard (JIS). 2 (642 mm 2) is defined as the time required to pass through the membrane area. Specifically, the Gurley permeability of the polyolefin membrane according to Preparation Examples 1 to 3 was measured in accordance with ISO 5636-5:2013, and the Gurley permeability of the cellulose membrane according to Comparative Preparation Examples 1 and 2 was measured by taking three specimens of 100 mm x 200 mm and using the JIS C2300ㆍ2:2010 21.2 Gurley method (JIS P8117:2009).

[0133] Classification Comparison Preparation Example 1 Comparison Preparation Example 2 Implementation Preparation Example 1 Implementation Preparation Example 2 Implementation Preparation Example 3 Material Cellulose Cellulose Polyolefin (M w =600,000 g / mol) polyolefin (M w =600,000 g / mol) polyolefin (M w =600,000 g / mol) Thickness (㎛) 253591216 Density (g / cm) 3 )0.35~0.460.35~0.45---Basis weight (g / m) 2 )--5.02 g / m 2 6.5 g / m 2 7.85 g / m 2 Porosity (%)--42.3745.2547.65Gulley Permeability (s / 100ml)1~83~10107105104

[0134] [Manufacturing Example 1: Manufacturing of an Ultracapacitor]

[0135] Manufacturing steps of the anode:

[0136] (i) BET surface area of ​​about 1,600 to 2,420 m 2 / g, and (ii) average particle size (D 50 ) was mixed with activated carbon powder having a particle size of about 8 μm; a conductive material (Super-P); and a mixed binder containing carboxymethyl cellulose (CMC) and SBR as binders at a weight ratio of 1:1 at a weight ratio of 90:5:5 (activated carbon:conductive material:mixed binder), and added to pure water (H2O) to prepare a cathode slurry having a total solid content of about 35 wt%.

[0137] The above positive electrode slurry was coated on both sides of aluminum foil (thickness: approximately 20 μm), and then dried to produce a preliminary positive electrode. The preliminary positive electrode was then thermo-compressed (pressed) to produce a positive electrode having a final thickness of approximately 200 μm.

[0138] Cathode manufacturing steps:

[0139] (i) BET surface area of ​​about 1,600 to 2,420 m 2 / g, and (ii) average particle size (D 50 ) was mixed with activated carbon powder having a particle size of about 8 μm; a conductive material (Super-P); and a mixed binder containing carboxymethyl cellulose (CMC) and SBR as binders at a weight ratio of 1:1 at a weight ratio of 90:5:5 (activated carbon:conductive material:mixed binder), and added to pure water (H2O) to prepare a cathode slurry having a total solid content of about 35 wt%.

[0140] The above cathode slurry was coated on both sides of aluminum foil (thickness: approximately 20 μm), and then dried to produce a preliminary cathode. The preliminary cathode was then thermo-compressed (pressed) to produce a final cathode having a thickness of approximately 180 μm.

[0141] Manufacturing steps of the winding element:

[0142] The positive electrode, the negative electrode, and the separator of each of the above manufacturing preparation examples were wound using a winding machine to manufacture a winding element.

[0143] Preparation steps for electrolyte:

[0144] An electrolyte having a concentration of approximately 1.0 M was prepared by dissolving a salt containing tetraethyl ammonium and hexafluorophosphate in acetonitrile, a solvent.

[0145] Manufacturing steps of ultracapacitors:

[0146] After placing the above-mentioned winding element in an aluminum case, the above-mentioned electrolyte was poured into the aluminum case, and then the aluminum case was pressurized at a pressure of 0.1 to 5 bar for 10 seconds to 3 minutes, and then sealed to manufacture an ultracapacitor (cylindrical full cell).

[0147] [Experimental Example 1: Performance Evaluation of Ultracapacitors]

[0148] How to control the capacitance of a cell:

[0149] The capacitance of the cell was adjusted according to the size of the cell.

[0150] How to measure cell capacitance and AC-ESR:

[0151] The capacitance was measured under 5 V and 5 A conditions using a battery charge / discharge capacity meter (model number: PEBC0505) from PNE Solutions.

[0152] AC-ESR was measured using a Hioki battery tester-resistance meter (model number: BT3562) after cell manufacturing and aging at 65℃ for 6 hours. Specifically, the measurement source frequency was set to 1 kHz ± 0.2 Hz, the measurement current was set to 100 Ma (3 mΩ range) to 10 Ma (3000 Ω range), and the open-circuit voltage was set to 25 V peak (3 / 30 mΩ range), 7 V peak (300 mΩ range), and 4 V peak (3Ω to 3000 Ω range).

[0153] Separator capacitance (F)Separator materialSeparator thickness (L, ㎛)AC-ESR (R, mΩ)P 1) =L*R* Comparative Example 1 Comparative Preparation Example 1 100 Cellulose 253.3825 Comparative Example 2 Comparative Preparation Example 2 353.31155 Embodiment 1 Embodiment Preparation Example 1 Polyolefin 93.3297 Embodiment 2 Embodiment Preparation Example 2 123.3396 Embodiment 3 Embodiment Preparation Example 3 163.3528 Comparative Example 3 Comparative Preparation Example 1 350 Cellulose 251.8842 Comparative Example 4 Comparative Preparation Example 2 351.81179 Embodiment 4 Embodiment Preparation Example 1 Polyolefin 91.6269 Example 5 Preparation Example 2 121.6359 Example 6 Preparation Example 3 161.6479 Comparative Example 5 Preparation Example 1 600 Cellulose 251.6980 Comparative Example 6 Preparation Example 2 351.51286 Example 7 Preparation Example 1 Polyolefin 91.5331 Example 8 Preparation Example 2 121.5441 Example 9 Preparation Example 3 161.55881) P is a value rounded to the first decimal place.

[0154] Capacity retention rate:

[0155] Some of the cells manufactured by the method according to Manufacturing Example 1 above were left in an environment of 75°C under conditions of constant current charging and constant voltage for 288 hours, and then the residual capacity and resistance were measured.

[0156] Separator membrane P=L*R* Capacity maintenance rate (%) Comparative example 1 Comparative preparation example 182586.6 Exemplary example 3 Exemplary preparation example 352891.9 Comparative example 3 Comparative preparation example 184286.2 Exemplary example 6 Exemplary preparation example 347989.7 Comparative example 5 Comparative preparation example 198084.9 Exemplary example 9 Exemplary preparation example 358886.3

[0157] In Table 2 above, when Comparative Examples 1 to 6 and Examples 1 to 9 are compared with each other, if the new parameter (P) derived by multiplying the thickness of the separator, the AC equivalent series resistance, and the square root of the electrostatic capacitance satisfies 800 or less, the same capacity can be achieved even with a thinner separator. In addition, if necessary, more electrodes can be wound to increase the energy density, and thus, freedom can be secured in the configuration of components or capacity adjustment in the manufacture of ultracapacitors, which is desirable. In addition, referring to Table 3 above, it was confirmed that excellent capacity retention can be achieved if the new parameter (P) derived by multiplying the thickness of the separator, the AC equivalent series resistance, and the square root of the electrostatic capacitance satisfies 800 or less.

[0158] The features described in the above-described embodiment may be combined with other embodiments unless explicitly stated otherwise. Furthermore, while the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art utilizing the basic concepts of the present invention defined in the following claims also fall within the scope of the present invention.

[0159] [Explanation of symbols]

[0160] 100: Ultracapacitor

[0161] 10: Bipolar

[0162] 20: Membrane

[0163] 30: Cathode

Claims

1. Bipolar; cathode; a separator interposed between the positive electrode and the negative electrode; and Containing an electrolyte; P in the following equation 1 satisfies 800 or less, Ultracapacitors: [Formula 1] P= L x R x In the above equation 1, L is the thickness (㎛) of the above membrane, R is the AC equivalent series resistance (mΩ) of the above ultracapacitor, F is the capacitance (F) of the above ultracapacitor.

2. In paragraph 1, The above positive and negative electrodes Containing activated carbons that are identical or different from each other, Ultra capacitor.

3. In paragraph 1, The BET specific surface area of ​​the activated carbon contained in the above anode is 1,500 to 2,500 m 2 / g and, The BET specific surface area of ​​the activated carbon included in the above cathode is 1,500 to 2,500 m 2 / g person, Ultra capacitor.

4. In paragraph 1, The above separator comprises a polyolefin resin. Ultra capacitor.

5. In paragraph 1, The thickness of the above separation membrane is 5 to 20 ㎛, Ultra capacitor.

6. In paragraph 1, The porosity of the above membrane is 40 to 70 vol%, Ultra capacitor.

7. In paragraph 1, The capacitance of the above ultracapacitor is 50 to 4000 F. Ultra capacitor.

8. In paragraph 1, The AC equivalent series resistance of the above ultracapacitor is 4 mΩ or less. Ultra capacitor.

9. In paragraph 1, P in the above formula 1 is less than or equal to 784, Ultra capacitor.

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