Electrochemical device and electronic device including the same

Abstract

The present application relates to an electrochemical device and an electronic device including the same. The electrochemical device comprises a positive electrode and an electrolyte, wherein the electrolyte comprises ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN); wherein the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises a metal element A, wherein the metal element comprises at least one element selected from Mg, Zr, or Al; wherein, based on the mass of the electrolyte, the mass content of SN is a%, the mass content of EC is b%, and the mass content of PC is c%, where k = b / c, 1.25 ≤ k ≤ 6, and a / k ≥ 0.2; furthermore, based on the mass of the positive electrode active material, the mass content of the metal element A is x%, where 0.01 ≤ x ≤ 1. The electrochemical device exhibited excellent high-temperature cycle performance and high-temperature intermittent cycle performance.

Description

Technology Field

[0001] The present application relates to the field of energy storage, and in particular, to electrochemical devices and electronic devices including the same. Background Technology

[0002] Rechargeable electrochemical devices are one of the most attractive energy storage systems due to their advantages, such as high energy density, a relatively simple reaction mechanism, high operating voltage, long lifespan, and eco-friendliness. Currently, electrochemical devices such as lithium-ion batteries are widely applied in various fields, including wearable devices, smartphones, drones, and laptops.

[0003] As the application fields of electrochemical devices continue to expand, market requirements for the cycle performance of electrochemical devices, such as lithium-ion batteries, are becoming increasingly high, particularly regarding high-temperature cycle performance and high-temperature intermittent cycle performance. For example, laptops are tools frequently used by people for work; they are generally always in a charged state during use and often generate heat during the charging and usage processes. In this process, the laptop is first charged to a full charge, maintained in a full charge state for several hours, and finally discharged when the charger is cut off. This process not only requires the electrochemical device of the laptop to possess high-temperature cycle performance (i.e., undergoing multiple "charge-discharge" cycles at high temperatures), but also imposes higher requirements for high-temperature intermittent cycle performance (i.e., undergoing multiple "charge-maintain full charge state for several hours-discharge" cycles at high temperatures). In light of this, the present application focuses on obtaining an electrochemical device with excellent high-temperature cycle performance and high-temperature intermittent cycle performance to satisfy the aforementioned needs of the people. The problem to be solved

[0004] At least to solve the above problem, the present application aims to improve the high-temperature cycle performance and high-temperature intermittent cycle performance of an electrochemical device by adjusting the composition of the electrolyte, the composition of the cathode active material, and the compatibility between the electrolyte and the cathode. means of solving the problem

[0005] According to one aspect of the present application, the present application provides an electrochemical device comprising a positive electrode and an electrolyte, wherein the electrolyte comprises ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN), the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises a metal element A, and the metal element comprises at least one element among Mg, Zr, or Al; wherein, based on the mass of the electrolyte, the mass content of SN is a%, the mass content of EC is b%, and the mass content of PC is c%, where k = b / c, 1.25 ≤ k ≤ 6, and a / k ≥ 0.2; furthermore, based on the mass of the positive electrode active material, the mass content of the metal element A is x%, where 0.01 ≤ x ≤ 1.

[0006] According to an embodiment of the present application, x / k ≤ 0.4.

[0007] According to an embodiment of the present application, 0.001≤x / a≤1.

[0008] According to an embodiment of the present application, the positive active material comprises lithium cobalt oxide.

[0009] According to an embodiment of the present application, the positive active material comprises lithium nickel cobalt manganese oxide.

[0010] According to an embodiment of the present application, the positive electrode active material comprises lithium cobalt oxide and lithium nickel cobalt manganese oxide, and based on the mass of the positive electrode active material, the mass ratio of the lithium cobalt oxide to the lithium nickel cobalt manganese oxide is g, and 1≤g≤9.

[0011] According to an embodiment of the present application, the positive active material comprises lithium cobalt oxide, and the median diameter Dv50 of the lithium cobalt oxide is m μm, where 8≤m≤20.

[0012] According to an embodiment of the present application, the median diameter Dv50 of the positive electrode active material is y μm, where 2≤y≤25.

[0013] According to an embodiment of the present application, 10≤y / x≤900.

[0014] According to an embodiment of the present application, 1≤y / a≤36.

[0015] According to an embodiment of the present application, the electrolyte further comprises lithium difluorophosphate (LiPO2F2), wherein, based on the mass of the electrolyte, the mass content of LiPO2F2 is d%, where 0.01≤d≤0.5.

[0016] According to an embodiment of the present application, 0.05≤d / x≤25.

[0017] According to an embodiment of the present application, 0.001≤d / k≤0.4.

[0018] According to another aspect of the present application, the present application further provides an electronic device, said electronic device comprising an electrochemical device according to an embodiment of the present application. Specific details for implementing the invention

[0019] The embodiments of the present application are described in detail below. The embodiments of the present application should not be interpreted as limiting the present invention.

[0020] As used in this application, the terms “comprehensive,” “containing,” and “include” are used in an open, non-restrictive sense.

[0021] Additionally, the present specification may indicate quantities, ratios, and other numerical values ​​in the form of ranges. Such range forms should be understood as being for convenience and brevity, and the ranges should not only include numerical values ​​specified as being limited to the range, but also flexibly understand that all individual numerical values ​​or sub-ranges encompassed within the ranges are included in the ranges as specified for each respective numerical value and sub-range.

[0022] In the specific details for the practice of the invention and the claims, a list of items linked by the terms “at least one of,” “at least one of,” “at least one of,” or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0023] The electrolyte is a key component of electrochemical devices and is used for the transport of lithium ions between the anode and cathode. By enabling the anode and cathode materials to continuously absorb and release lithium ions, it enables charge and discharge functions. Therefore, the electrolyte plays a crucial role in enabling electrochemical devices to achieve excellent high-temperature performance.

[0024] One of the main features of the electrolyte described in the present application is that the electrolyte simultaneously comprises ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN), wherein, based on the mass of the electrolyte, the mass content of succinonitrile is a%, the mass content of ethylene carbonate is b%, and the mass content of propylene carbonate is c%, wherein k = b / c, 1.25 ≤ k ≤ 6, and a / k ≥ 0.2.

[0025] The reason the above electrolyte is provided in this application is that it has been discovered through this application that adding a specific amount of ethylene carbonate to the electrolyte can improve the high pressure resistance and high temperature stability of the electrolyte itself. However, if the content of ethylene carbonate in the electrolyte is excessively high, gas generation becomes severe, which is disadvantageous for high-temperature intermittent cycle performance. On the other hand, since propylene carbonate has excellent high-temperature stability, adding propylene carbonate can compensate for the shortcomings of ethylene carbonate. Therefore, by simultaneously adding ethylene carbonate and propylene carbonate to the electrolyte, the high-temperature stability of the electrolyte itself can be improved, thereby improving the high-temperature intermittent cycle performance and high-temperature cycle performance of the electrochemical device. In addition, adding a nitrile compound to the electrolyte effectively stabilizes the transition metal (e.g., cobalt metal in lithium cobalt oxide) in the positive electrode active material and reduces the leaching of the transition metal, thereby stabilizing the structure of the positive electrode active material and further improving the cycle stability and high-temperature performance of the electrochemical device. Here, the reason why the effect of adding succinonitrile (SN) to the electrolyte is much more pronounced than that of adding other nitrile compounds is that coordination complexation occurs between the cyano group in the structure of succinonitrile and the metal ion in the positive electrode active material, which can reduce side reactions between the positive electrode active material and the electrolyte and reduce gas generation inside the electrochemical device; furthermore, the cyano group reacts with water or hydrogen fluoride in the electrolyte to improve the cycle stability of the electrolyte and further improve the high-temperature cycle performance of the electrochemical device.

[0026] However, the present application has discovered that although propylene carbonate possesses excellent high-temperature stability, it can easily undergo reductive decomposition on the surface of the graphite anode under the lithium absorption potential, thereby destroying the graphite structure, affecting the release of active ions, and further affecting the cycle stability of the electrochemical device. Additionally, it has been discovered that while succinonitrile can effectively stabilize the transition metal in the cathode active material, if the amount added is relatively large, it can increase the resistance of the electrochemical device and cause relatively large polarization. Accordingly, the present application promotes the synergistic effect of the three elements by controlling the mass content of ethylene carbonate, propylene carbonate, and succinonitrile in the electrolyte and the mixing relationship thereof to satisfy 1.25≤k≤6 and a / k≥0.2, thereby further improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. In some embodiments, k may be 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 or within a range consisting of any two of the above values, but is not limited thereto. In some embodiments, a / k may be 0.2, 0.5, 1, 1.5, 2 or within a range consisting of any two of the above values, but is not limited thereto.

[0027] The anode is a major component of an electrochemical device and exerts a similarly significant influence on the performance of electrochemical performance. The anode comprises an anode current collector and an anode active material layer located on at least one surface of the anode current collector, wherein the anode active material layer comprises an anode active material. The anode active material comprises a material capable of reversibly absorbing and releasing active ions, such as lithium ions. The anode active material layer may be a single layer or a multilayer, and each layer among the multilayer anode active material layers may comprise the same or different anode active materials. Additionally, the anode active material layer further comprises a binder and / or a conductive agent.

[0028] One of the main features of the anode described in the present application is that the anode active material is doped with a metal element A comprising at least one element among Mg, Zr, or Al, wherein, based on the mass of the anode active material, the mass content of the metal element A is x%, where 0.01≤x≤1.

[0029] The reason for submitting the above-mentioned anode in this application is that it has been discovered through this application that when the anode active material is doped with at least one of Mg, Zr, or Al, the structure of the anode active material can be more stabilized compared to when it is doped with other metal elements. For example, when the anode active material contains the active metal element cobalt (Co), element A occupies the crystal lattice spacing. The AO bond formed after lithium release from the anode is stronger than the Co-O bond, which can mitigate the release of oxygen and prevent the leaching of Co, thereby achieving the objective of stabilizing the structure of the anode active material. Furthermore, by controlling the mass content of metal element A in the anode active material to be within the range of 0.01% to 1%, the release of active ions such as lithium ions from the anode active material is promoted, and polarization is reduced, thereby further promoting the improvement of high-temperature cycle performance and high-temperature intermittent cycle performance. In some embodiments, x may be 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or within a range consisting of any two of the above values, but is not limited thereto.

[0030] In addition, by using an electrolyte and an anode having the above characteristics in combination, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved. This is thought to be because the electrolyte and the anode have a good compatibility relationship, which can promote the performance of each other's roles.

[0031] Furthermore, by controlling the appropriate combination between a component in the electrolyte and the cathode active material, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved.

[0032] In some embodiments, the high-temperature performance can be further improved by controlling the relationship between the content x% of doped element A in the cathode active material and the mixing ratio k of ethylene carbonate and propylene carbonate in the electrolyte. This is because although propylene carbonate possesses excellent high-temperature stability, it can easily decompose at the cathode and destroy the cathode structure; however, by having ethylene carbonate decompose at the cathode surface to form a stable SEI film, the action of propylene carbonate decomposing at the cathode interface and destroying the cathode can be weakened. Therefore, using both together can improve the high-pressure performance and high-temperature stability of the electrolyte itself, and doping with element A can stabilize the structure of the cathode active material. Thus, by controlling the relationship between the content of doped element A and the mixing ratio k of ethylene carbonate and propylene carbonate, the high-pressure performance and high-temperature stability of the electrolyte can be improved, while the stability of the cathode structure can be improved, and the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved. In some embodiments, x / k ≤ 0.4. In some embodiments, x / k ≤ 0.3, x / k ≤ 0.2, or x / k ≤ 0.1.

[0033] In some embodiments, further improvement of the high-temperature performance can be achieved by controlling the relationship between the content x% of doped element A in the positive electrode active material and the content a% of succinonitrile in the electrolyte. This is because coordination complexation occurs between the cyano group in the succinonitrile structure and the metal ion in the positive electrode active material, thereby stabilizing the structure of the positive electrode active material, and by controlling the content relationship between the two, the structure of the positive electrode active material is relatively well stabilized, while the electrolyte can have a relatively low resistance. In some embodiments, 0.001 ≤ x / a ≤ 1. In some embodiments, x / a may be within the range consisting of 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1 or any two of the above values, but is not limited thereto.

[0034] When the positive active material particles are primary particles, the median diameter Dv50 of the positive active material refers to the diameter of the primary particles of the positive active material particles. When the primary particles of the positive active material particles aggregate to form secondary particles, the median diameter Dv50 of the positive active material refers to the diameter of the secondary particles of the positive active material particles.

[0035] In some embodiments, the median diameter Dv50 of the positive active material is yμm, where 2≤y≤25. In some embodiments, the median diameter Dv50 of the positive active material may be 2μm, 3μm, 5μm, 8μm, 10μm, 13μm, 15μm, 18μm, 20μm, 23μm, 25μm, or within a range consisting of any two of the above values, but is not limited thereto. When the median diameter Dv50 of the positive active material is within the above range, not only can good contact between the positive active material particles be ensured, but the contact area between the positive active material and the electrolyte can also be secured within an appropriate range, thereby reducing the occurrence of side reactions and avoiding excessive consumption of the electrolyte during the electrochemical cycle, while simultaneously reducing the risk of cracking of the positive active material particles due to cold pressing during the electrode manufacturing process.

[0036] In some embodiments, the positive electrode active material comprises one or more of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate (LiVOPO4), lithium iron phosphate, lithium titanium oxide, and lithium-containing manganese-based materials.

[0037] In some embodiments, the chemical formula of the lithium cobalt oxide may be LiCoO2, but is not limited thereto.

[0038] In some embodiments, the chemical formula of lithium nickel cobalt manganese oxide is LiNi 0.6 Co 0.2 Mn 0.2 It may be O2, but is not limited to this.

[0039] In some embodiments, the positive electrode active material comprises at least one of lithium cobalt oxide or lithium nickel cobalt manganese oxide, wherein, where the positive electrode active material comprises both lithium cobalt oxide and lithium nickel cobalt manganese oxide, the mass ratio of the lithium cobalt oxide to the lithium nickel cobalt manganese oxide is g based on the mass of the positive electrode active material, and 1 ≤ g ≤ 9. In some embodiments, g may be 1, 2, 3, 4, 5, 6, 7, 8, or 9, or may be within a range consisting of any two numerical values, but is not limited thereto.

[0040] In some embodiments, the positive electrode active material comprises lithium cobalt oxide, and the median diameter Dv50 of the lithium cobalt oxide is m μm, where 8 ≤ m ≤ 20. By controlling the median diameter of the lithium cobalt oxide to be within the above range, the electrolyte can not only improve the electrolyte impregnation degree of the positive electrode active material, but also improve the rate at which the positive electrode active material absorbs and releases metal ions such as lithium ions, thereby further improving the electrochemical performance of the electrochemical device.

[0041] In some embodiments, the median diameter Dv50 (y μm) of the positive active material and the content x% of metal element A in the positive active material satisfy 10 ≤ y / x ≤ 900. When y / x is within the above range, the structural stability of the positive active material and its thermal stability at high temperatures can be simultaneously improved, thereby further improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. In some embodiments, 20 ≤ y / x ≤ 800, 20 ≤ y / x ≤ 600, or 50 ≤ y / x ≤ 500.

[0042] In some embodiments, the median diameter Dv50 (yμm) of the positive electrode active material and the mass content a% of succinonitrile in the electrolyte satisfy 1 ≤ y / a ≤ 36. When y / a is within the above range, the complexation between succinonitrile and the transition metal in the positive electrode active material is further promoted, and the leaching of the transition metal is reduced, thereby improving the structural stability of the positive electrode active material and its thermal stability at high temperatures, and thus improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. In some embodiments, 2 ≤ y / a ≤ 30, 5 ≤ y / a ≤ 20, or 5 ≤ y / a ≤ 15.

[0043] In some embodiments, the electrolyte further comprises lithium difluorophosphate (LiPO2F2), wherein the addition of lithium difluorophosphate can induce a decomposition reaction on the surface of the cathode to form a structurally stable SEI film, thereby further improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. This is specifically illustrated by the fact that the addition of lithium difluorophosphate increases the LiF component in the SEI film, thereby enhancing the stability of the SEI film and reducing the occurrence of side reactions.

[0044] In some embodiments, based on the mass of the electrolyte, the mass content of LiPO2F2 is d%, where 0.01 ≤ d ≤ 0.5. When the mass content of LiPO2F2 is within the above range, LiPO2F2 is sufficiently dissolved in the electrolyte, which not only significantly improves the high-temperature performance of the electrochemical device but also ensures the formation of an SEI film with appropriate resistance and reduces polarization. In some embodiments, d may be 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, or within the range between any two of the above values, but is not limited thereto.

[0045] In some embodiments, the mass content d% of the LiPO2F2 and the content x% of the metal element A in the positive electrode active material satisfy 0.05 ≤ d / x ≤ 25. When d / x is within the above range, the LiPO2F2 has relatively better solubility in the electrolyte and forms an SEI film with relatively low resistance at the cathode, and furthermore, the metal element in the positive electrode active material can better stabilize the structure of the positive electrode active material, promote the release of active ions such as lithium ions from the positive electrode active material, and simultaneously improve the cycle stability of the positive electrode and the cathode, thereby further improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. In some embodiments, d / x may be 0.05, 0.1, 0.5, 1, 3, 5, 7, 9, 12, 15, 20, 25, or within the range between any two of the above numerical values, but is not limited thereto.

[0046] In some embodiments, the mass content d% of the LiPO2F2 and the mixing ratio k of ethylene carbonate and propylene carbonate in the electrolyte satisfy 0.001 ≤ d / k ≤ 0.4. When d / k is within the above range, the electrolyte has lower resistance and better high-temperature resistance performance, and at the same time, can form a SEI film with lower resistance at the cathode interface, thereby further improving the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device. In some embodiments, d / k may be 0.001, 0.05, 0.1, 0.2, 0.3, 0.4, or within the range between any two of the above numerical values, but is not limited thereto.

[0047] A material different from its composition may be attached to the surface of the above-mentioned positive active material. Examples of surface-attached materials include, but are not limited to, at least one of aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; at least one of lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon. As the material is attached to the surface of the positive active material, the oxidation reaction of the electrolyte on the surface of the positive active material can be suppressed, and the service life of the electrochemical device can be shortened.

[0048] In this application, a positive active material having a material with a composition different from that of the positive active material attached to its surface is also referred to as a "positive active material."

[0049] In some embodiments, the shape of the positive active material particles includes, but is not limited to, block-shaped, polyhedral-shaped, spherical, elliptical-spherical, plate-shaped, needle-shaped, and columnar-shaped particles. In some embodiments, the positive active material particles include primary particles, secondary particles, or a combination thereof. In some embodiments, the primary particles may aggregate to form secondary particles.

[0050] In some embodiments, the binder in the positive active material layer comprises, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, polyvinylidene fluoride, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylate styrene butadiene rubber, epoxy resin, or nylon.

[0051] In some embodiments, the conductive agent in the positive active material layer comprises, but is not limited to, carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, synthetic graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer comprises a polyphenylene derivative.

[0052] The present application does not specifically limit the type of positive current collector, and the positive current collector may be any material known to be suitable for use as a positive current collector. Examples of positive current collectors may include, but are not limited to, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. In some embodiments, the positive current collector is a metal material. In some embodiments, the positive current collector is aluminum. To reduce the electronic contact resistance between the positive current collector and the positive active material layer, a conductive additive may be included on the surface of the positive current collector. Examples of conductive additives may include, but are not limited to, carbon and precious metals such as gold, platinum, and silver.

[0053] A positive electrode can be manufactured by forming a positive electrode active material layer containing a positive electrode active material, a binder, or a conductive agent on a current collector. The manufacture of a positive electrode using a positive electrode active material can be carried out through conventional methods, namely, by dry mixing a positive electrode active material, a binder, and, depending on the demand, a conductive agent and a thickener, etc., to form a sheet, and then pressing the resulting sheet-like material onto a positive electrode current collector, or by dissolving or dispersing these materials in a liquid medium to form a slurry, applying the slurry to a positive electrode current collector, and drying it to form a positive electrode active material layer on the current collector, thereby obtaining a positive electrode. In some embodiments, the liquid medium may include N-methylpyrrolidone, but is not limited thereto.

[0054] In some embodiments, the electrolyte further comprises any non-aqueous solvent known to be usable as a solvent for the electrolyte in the prior art.

[0055] In some embodiments, the non-aqueous solvent comprises one or more of cyclic carbonates, chain carbonates, cyclic carboxylates, chain carboxylates, cyclic ethers, chain ethers, or aromatic fluorine-containing solvents, but is not limited thereto.

[0056] In some embodiments, examples of the cyclic carbonate may include butylene carbonate, but are not limited thereto.

[0057] In some embodiments, examples of the chain-type carbonates may include, but are not limited to, one or more of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC), methyl n-propyl carbonate, ethyl n-propyl carbonate, or din-propyl carbonate.

[0058] In some embodiments, examples of the cyclic carboxylate may include, but are not limited to, one or more of γ-butyrolactone and γ-valerolactone. In some embodiments, some hydrogen atoms of the cyclic carboxylate may be substituted with fluorine.

[0059] In some embodiments, examples of the chain-type carboxylate may include, but are not limited to, one or more of methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate, and methyl pivalate. In some embodiments, some hydrogen atoms of the chain-type carboxylate may be substituted with fluorine. In some embodiments, examples of fluorine-substituted chain-type carboxylates may include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate and 2,2,2-trifluoroethyl trifluoroacetate.

[0060] In some embodiments, examples of the cyclic ether may include, but are not limited to, one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, and dimethoxypropane.

[0061] In some embodiments, examples of the chain-type ether may include, but are not limited to, one or more of dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane, and 1,2-ethoxymethoxyethane.

[0062] In some embodiments, the aromatic fluorine-containing solvent comprises one or more of fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene, but is not limited thereto.

[0063] In some embodiments, the electrolyte may be any material known as an electrolyte and is not particularly limited. Examples of electrolytes include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, LiWF7; lithium tungsten oxides such as LiWOF5; lithium carboxylate salts such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, CF3CF2CF2CF2CO2Li; lithium sulfonicate salts such as FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li; Lithium imide salts such as LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic lithium 1,2-perfluoroethanebis(sulfonyl)imide, cyclic lithium 1,3-perfluoropropanebis(sulfonyl)imide, LiN(CF3SO2)(C4F9SO2), etc.; methylated lithium salts such as LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, etc.; lithium (maloneto)borate salts such as lithium bis(maloneto)borate salts, lithium difluoro(maloneto)borate salts, etc.; Lithium (malonato)phosphate salts such as lithium tris(malonato)phosphate, lithium difluorobis(malonato)phosphate, lithium tetrafluoro(malonato)phosphate, etc.; and fluorine-containing organic lithium salts such as LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2, etc.; lithium oxalatoborate salts such as lithium difluorooxalatoborate, lithium bis(oxalato)borate, etc.It may include, but is not limited to, lithium oxalatophosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalato)phosphate, tris(oxalato)phosphate, etc.;

[0064] In some embodiments, the electrolyte comprises at least one of LiPF6, LiBF4, LiSbF6, FSO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), and LiN(CF3SO2)2. In this application, the content of the electrolyte is not particularly limited as long as it does not impair the effects of this application. In some embodiments, the mass content of the electrolyte is 10% to 15% based on the mass of the electrolyte. When the mass content of the electrolyte is within the above range, the viscosity of the electrolyte can be kept within a suitable range, so that good conductivity can be easily secured.

[0065] In the present application, the cathode comprises a cathode current collector and a cathode active material layer installed on at least one surface of the cathode current collector, and the cathode active material layer comprises a cathode active material. The cathode active material layer may be a single layer or a multilayer, and each layer among the multilayer cathode active material layers may comprise the same or different cathode active materials. The cathode active material is any material capable of reversibly absorbing and releasing active ions, such as lithium ions. Examples of cathode active materials include lithium metal, structured lithium metal, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O 12 or may include Li-Al alloys, but is not limited thereto.

[0066] The present application does not specifically limit the type of negative current collector, and any known current collector may be used. Examples of negative current collectors include, but are not limited to, aluminum foil, copper foil, nickel foil, stainless steel foil, or nickel-plated steel foil. In some embodiments, the negative current collector is copper foil.

[0067] The cathode active material layer may include a cathode binder, a conductive agent, or a thickener. The cathode binder can improve the bonding between the cathode active material particles and the bonding between the cathode active material and the current collector. The type of cathode binder is not particularly limited as long as it is a material that is stable with respect to the electrolyte or the solvent used in manufacturing the electrode. In some embodiments, the cathode binder includes, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylate styrene butadiene rubber, epoxy resin, or nylon.

[0068] In some embodiments, the conductive agent comprises, but is not limited to, at least one of a carbon-based material, a metal-based material, and a conductive polymer. In some embodiments, the carbon-based material comprises at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fiber; in some embodiments, the metal-based material comprises at least one of metal powder, metal fiber, copper, nickel, and aluminum; and in some embodiments, the conductive polymer comprises a polyphenylene derivative. In some embodiments, the thickener comprises sodium carboxymethyl cellulose.

[0069] The cathode can be manufactured through manufacturing methods known in the art to which this application belongs. For example, a cathode can be obtained by applying a cathode active material layer slurry comprising a cathode active material, a binder, or a conductive agent to a cathode current collector, and by applying said slurry to both sides of the cathode current collector to form a cathode active material layer. In some embodiments, the solvent may include water, but is not limited thereto.

[0070] In some embodiments, the electrochemical device of the present application is provided with a separator between the anode and the cathode to prevent short circuits. The present application does not specifically limit the material and form of the separator, and any technology disclosed in the prior art may be used as long as it does not affect the effects of the present application.

[0071] For example, the separator may include a substrate layer and a surface treatment layer. The substrate layer may include a porous sheet or a nonwoven material having excellent liquid retention properties. Examples of materials for the resin or glass fiber separator may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The materials of the separator may be used alone or optionally in combination. The substrate layer may also be a material laminated with the above materials, and examples thereof include, but are not limited to, a three-layer separator laminated in the order of polypropylene, polyethylene, and polypropylene.

[0072] A surface treatment layer is installed on at least one surface of a substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material. Examples of inorganic materials may include oxides such as aluminum oxide and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates (e.g., barium sulfate, calcium sulfate, etc.), but are not limited thereto. The form of the inorganic material may include particulates or fibers, but is not limited thereto. A polymer is included in the polymer layer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0073] The components of an electrochemical device include an electrode set, a current collection structure, a case, and a protection element.

[0074] The electrode set may be any one of a laminated structure formed by stacking the anode and cathode through the separator, and a structure formed by winding the anode and cathode through the separator.

[0075] The current collection structure is a structure designed to lower the resistance of the wiring portion and the junction portion. When the electrode set is the above-mentioned laminated structure, it is suitable to use a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminal. When the electrode set is the above-mentioned wound structure, two or more lead wire structures are installed on the positive and negative electrodes respectively, and these are bundled to the terminal to lower the internal resistance.

[0076] The material of the case is not particularly limited as long as it is a material that is stable with respect to the electrolyte used. The case may be made of metals such as nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminate of resin and aluminum foil, but is not limited thereto. In some embodiments, the outer case is a metal or laminate of aluminum or aluminum alloy. The shape of the case is also arbitrary and may be any one of, for example, cylindrical, square, laminated, button-shaped, etc.

[0077] The protection device may use a positive temperature coefficient (PTC) that increases resistance when abnormal heating occurs or an excessive current passes, a thermal fuse, a thermistor, a current cutoff valve, etc. The protection device may be selected as a device that does not operate under conditions of normal high-current use, and it may also be designed so that abnormal heating or thermal runaway does not occur even without the protection device.

[0078] The electrochemical device of the present application comprises any device in which an electrochemical reaction takes place, wherein said any device comprises, but is not limited to, a lithium lithium-ion battery. In some embodiments, the electrochemical device of the present application comprises a positive electrode having a positive active material capable of absorbing and releasing active ions of said any one embodiment, a negative electrode having a negative active material capable of absorbing and releasing active ions, and an electrolyte of said any one embodiment.

[0079] The present application further provides an electronic device, wherein the electronic device includes an electrochemical device according to the present application.

[0080] The use of the electrochemical device of the present application is not particularly limited, and the electrochemical device may be used as any electronic device already known in the prior art. In some embodiments, the electrochemical device of the present application may be used as a notebook, pen input computer, portable computer, e-book player, portable telephone, portable fax, portable copier, portable printer, headset, video, liquid crystal TV, portable vacuum cleaner, portable CD player, minidisc, transceiver, electronic notepad, calculator, memory card, portable recorder, radio, backup power supply, motor, automobile, motorcycle, electric bicycle, bicycle, lighting equipment, toy, game console, watch, power tool, flashlight, camera, household high-capacity storage battery and lithium-ion capacitor, etc., but is not limited thereto.

[0081] The present application is further explained below by citing a lithium-ion battery as an example and combining specific embodiments. However, as will be understood by those skilled in the art to which this application pertains, the manufacturing method described in this application is merely illustrative, and all other suitable manufacturing methods are also encompassed within the scope of this application.

[0082] First, the manufacture of lithium-ion batteries

[0083] 1. Preparation of the cathode

[0084] Artificial graphite as a cathode active material, styrene butadiene rubber (SBR) as a binder, and sodium carboxymethyl cellulose (CMC) as a thickener are sufficiently stirred and mixed in a weight ratio of 97.4:1.2:1.4 in a suitable amount of deionized water to form a uniform cathode slurry; the slurry is applied to a copper foil as a cathode current collector, dried, and cold-pressed to obtain a cathode.

[0085] 2. Manufacturing of the anode

[0086] In a suitable amount of N-methylpyrrolidone (NMP) solvent, lithium cobalt oxide or lithium nickel cobalt manganese oxide doped with Mg, Zr, or Al elements, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder are sufficiently stirred and mixed in a weight ratio of 96:2:2 to form a uniform anode slurry; the slurry is applied to an aluminum foil serving as an anode current collector, dried, and cold-pressed to obtain an anode.

[0087] 3. Preparation of electrolyte

[0088] In a glove box under an argon gas atmosphere with a moisture content <10 ppm, specific masses of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) are uniformly mixed, and sufficiently dried lithium salt LiPF6 is dissolved in the above non-aqueous solvent to form a base electrolyte; specific masses of additives (e.g., nitrile compound additives SN and LiPO2F2) are added to the obtained base electrolyte and uniformly mixed to obtain an electrolyte. Here, based on the mass of the electrolyte, the mass content of LiPF6 is 12.5%, the mass contents of EC, PC, SN, and LiPO2F2 are listed in the example table, and the remainder is the mass content of DEC in the electrolyte.

[0089] 4. Manufacture of separator membrane

[0090] A polyethylene (PE) porous polymer thin film is used as a separator.

[0091] 5. Manufacture of lithium-ion batteries

[0092] A positive electrode, a separator, and a negative electrode are stacked in sequence so that the separator acts as a separator between the positive electrode and the negative electrode, and then wound to obtain a battery cell; the battery cell is placed in an outer packaging box, the above-prepared electrolyte is injected into the dried battery cell, and the manufacturing of a lithium-ion battery is completed through processes such as vacuum sealing, packaging, settling, forming, and molding.

[0093] Lithium-ion batteries of the examples and comparative examples are manufactured according to the above manufacturing method, and the following tests are performed on the lithium-ion batteries, positive electrode active materials, and electrolytes.

[0094] Second, test method

[0095] 1. High-temperature cycle test

[0096] The battery is placed in a constant temperature box at 45°C and charged to 4.4V with a constant current of 1.5C, then charged from 4.4V to 0.05C with a constant voltage, and finally discharged to 3.0V with a constant current of 1.0C; this constitutes one charge-discharge cycle, and the first discharge capacity is recorded as C1. 500 charge-discharge cycles are performed in the above manner, and the discharge capacity after the 500th cycle is C 500 It is recorded as follows. The cycle capacity retention rate of the lithium-ion battery at 45°C is calculated using the following formula.

[0097] Cycle capacity retention rate = (C 500 / C1)Х100%.

[0098] 2. High-temperature intermittent cycle test

[0099] The battery is placed in a constant temperature box at 45°C and charged to 4.4V with a constant current of 0.5C, then charged from 4.4V to 0.05C with a constant voltage and maintained for 19.5h, and then discharged to 3.0V with a constant current of 0.5C. This constitutes one charge-discharge cycle process, and the first discharge capacity and the thickness when the battery is in a fully charged state during the first cycle are recorded as A1 and T1, respectively. 23 charge-discharge cycles are performed according to the above method. Subsequently, the battery is charged to 4.35V with a constant current of 0.5C, then charged from 4.35V to 0.05C with a constant voltage and maintained for 19.5h, and then discharged to 3.0V with a constant current of 0.5C; this constitutes one charge-discharge cycle. 113 charge-discharge cycles are re-executed according to the above method, and the discharge capacity after the final discharge is completed and the thickness when the battery is in a fully charged state during the final cycle are each A 136 Wow T 136 It is recorded as follows. The intermittent cycle capacity retention rate and thickness increase rate of the lithium-ion battery at 45°C are calculated using the following formula.

[0100] Intermittent cycle capacity retention rate = (A 136 / A1)Х100%;

[0101] Thickness increase rate = (T 136 / T1)Х100%.

[0102] 3. Test of the median diameter of the positive active material particles Dv50

[0103] The particle diameter of the positive active material particles is measured using a Malvern particle size analyzer. The positive material is placed in alcohol, which is a dispersant, and dispersed by ultrasound for 30 minutes. Then, the sample is added to the Malvern particle size analyzer and the test is started. Starting from the smallest particle diameter in the particle size distribution based on volume, the particle diameter at which the cumulative volume reaches 50% is the Dv50 of the positive material.

[0104] 4. Test for the content of Mg, Zr, or Al elements in the cathode active material

[0105] Discharge and disassemble the lithium-ion battery, and randomly select two locations of the positive active material layer (recorded as Location 1 and Location 2) to perform the following test.

[0106] 1) Obtain the positive active material from the positive active material layer at position 1 and perform an inductive coupling plasma (ICP) test to obtain the content of Mg, Zr, or Al elements in the positive active material;

[0107] 2) Perform a surface energy spectrum (EDS) test on the positive active material layer at position 2, magnify the test area 3,000 times, and perform an EDS test on the entire area to obtain the content of Mg, Zr, or Al elements in the positive active material;

[0108] The highest value of the two test results above is taken as the content of Mg, Zr, or Al elements in the cathode active material.

[0109] 5. Test of the content of each component in the electrolyte

[0110] After discharging the lithium-ion battery, it is decomposed and centrifuged; gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC) tests are performed on the liquid obtained from centrifugation to detect each component in the electrolyte and test their content.

[0111] Third, test results

[0112] Table 1 shows the effects of the cathode active material and electrolyte on the high-temperature cycle performance and high-temperature intermittent cycle performance of a lithium-ion battery. Here, the median diameter Dv50 of the cathode active material in the examples in Table 1 is all 15 μm; and the cathode active materials in Examples 1-2 to 1-7 are lithium cobalt oxide (LiCoO2) and lithium nickel cobalt manganese oxide (LiNi 0.6 Co 0.2 Mn 0.2O2) where the mass ratio of lithium nickel cobalt manganese oxide to lithium cobalt oxide is 3; and the positive active material in other examples and comparative examples 1-1 to 1-10 is lithium cobalt oxide (LiCoO2).

[0113] As can be seen from the data in Table 1, when compared to the comparative example, the electrolyte in the example contains EC, PC, and SN simultaneously, satisfying that their contents are 1.25≤k≤6 and a / k≥0.2, and additionally, the cathode active material in the example is doped with Mg, Zr, or Al elements, satisfying that their contents are 0.01≤x≤1, and the electrochemical device in the example has a relatively high capacity retention rate in both the 45°C cycle process and the intermittent cycle process, while also having a relatively low thickness increase rate in the 45°C intermittent cycle process.

[0114] In addition, by comparing Comparative Examples 1-6 and 1-7 with Example 1-1, it can be seen that better high-temperature performance can be obtained by adding SN to the electrolyte. Furthermore, by comparing Comparative Examples 1-8 and 1-9 with the Example, it can be seen that better high-temperature performance can be obtained when the content of EC, PC, and SN in the electrolyte simultaneously satisfies 1.25≤k≤6 and a / k≥0.2.

[0115] Comparing Comparative Examples 1-10 with Example 1, it can be seen that better high-temperature performance can be obtained when Mg is doped into the positive active material compared to when other metal elements (e.g., Zn) are doped into the positive active material. In addition, as can be seen from Examples 1-24 and 1-25, an electrochemical device with excellent high-temperature performance can be obtained even when Al or Zr is doped into the positive active material.

[0116] In addition, as can be seen by comparing Examples 1-30 to 1-31 with Example 1-11, if the electrochemical device further satisfies 0.001 ≤ x / a ≤ 1, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved. As can be seen by comparing Example 1-32 with Examples 1-22, 1-26, and 1-27, if the electrochemical device further satisfies x / k ≤ 0.4, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved.

[0117]

[0118]

[0119]

[0120] Tables 2 and 3 show the effect of the median diameter Dv50 of the positive electrode active material on the high-temperature cycle performance and high-temperature intermittent cycle performance of the lithium-ion battery. Here, all examples in Tables 2 and 3 are based on Examples 1-10, and the difference from Examples 1-10 lies only in the parameters listed in Tables 2 and 3.

[0121]

[0122] As can be seen from Table 2 above, when an electrochemical device satisfies 2≤y≤25 and 10≤y / x≤900 simultaneously, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved.

[0123]

[0124] As can be seen from Table 3 above, if the electrochemical device further satisfies 1≤y / a≤36, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved.

[0125] Examples 4-1 to 4-7 in Tables 4 and 5 are improved based on Example 1-10, Examples 4-8 and 4-9 in Table 4 are improved based on Example 1-22, and Examples 5-1 and 5-2 in Table 5 are improved based on Example 1-1, and the specific improvement is that a specific amount of LiPO2F2 is added to the electrolyte.

[0126]

[0127] Comparing Examples 4-1 to 4-7 with Example 1-10, it can be seen that when LiPO2F2 is further added to the electrolyte, both the high-temperature cycle performance and the high-temperature intermittent cycle performance of the correspondingly obtained electrochemical device are improved. Furthermore, as can be seen in Table 4, when the content d% of LiPO2F2 satisfies 0.01≤d≤0.5 and 0.05≤d / x≤25, the improvement effect on the electrochemical device is more pronounced.

[0128]

[0129] As can be seen from the data in Table 5, if the electrochemical device satisfies 0.001≤d / k≤0.4, the high-temperature cycle performance and high-temperature intermittent cycle performance of the electrochemical device can be further improved.

[0130] Throughout the specification, the reference to “Examples,” “Some Examples,” “One Example,” “Another Example,” “Examples,” “Specific Examples,” or “Some Examples” means that at least one example or example of this application includes the specific features, structures, materials, or properties described in that example or example. Accordingly, descriptions appearing throughout the specification, such as, for example, “In Some Examples,” “In Examples,” “In One Example,” “In Another Example,” “In One Example,” “In Specific Examples,” or “Examples,” do not necessarily refer to the same example or example in this application. Furthermore, the specific features, structures, materials, or properties described in this specification may be combined with one or more examples by any suitable means.

[0131] Although exemplary embodiments have been presented and described in this specification, as will be understood by those skilled in the art to which this application pertains, this application should not be interpreted as being limited by the embodiments described above, and the embodiments described above may be changed, substituted with equivalents, and modified without departing from the spirit, principles, and scope of this application.

Claims

Claim 1 An electrochemical device comprises a positive electrode and an electrolyte, wherein the electrolyte comprises ethylene carbonate, propylene carbonate, and succinonitrile, the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a metal element A, wherein the metal element A comprises at least one of Mg, Zr, or Al elements, and based on the mass of the electrolyte, the mass content of the succinonitrile is a%, the mass content of the ethylene carbonate is b%, and the mass content of the propylene carbonate is c%, where k = b / c, 1.25 ≤ k ≤ 6, and a / k ≥ 0.2, and also based on the mass of the positive electrode active material, the mass content of the metal element A is x%, where 0.01 ≤ x ≤ 1, and the electrolyte further comprises lithium difluorophosphate, and based on the mass of the electrolyte, the mass content of the lithium difluorophosphate is d%, where, Electrochemical device in which 0.01≤d≤0.5 and 0.05≤d / x≤25. Claim 2 An electrochemical device according to claim 1, wherein x / k ≤ 0.

4. Claim 3 An electrochemical device according to claim 1, wherein 0.001≤x / a≤1. Claim 4 An electrochemical device according to claim 1, wherein the positive active material comprises lithium cobalt oxide. Claim 5 An electrochemical device according to claim 1, wherein the positive active material comprises lithium nickel cobalt manganese oxide. Claim 6 An electrochemical device according to claim 1, wherein the positive electrode active material comprises lithium cobalt oxide and lithium nickel cobalt manganese oxide, and based on the mass of the positive electrode active material, the mass ratio of the lithium cobalt oxide to the lithium nickel cobalt manganese oxide is g, and 1 ≤ g ≤ 9. Claim 7 An electrochemical device according to claim 1, wherein the median diameter Dv50 of the positive active material is yμm, where 2≤y≤25. Claim 8 An electrochemical device according to claim 7, wherein 10≤y / x≤900. Claim 9 An electrochemical device according to claim 7, wherein 1≤y / a≤36. Claim 10 delete Claim 11 delete Claim 12 An electrochemical device satisfying 0.006≤d / k≤0.4 in claim 1. Claim 13 An electronic device comprising an electrochemical device according to any one of claims 1 to 9 and 12.

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