Electrochemical apparatus and electronic apparatus including the same

Abstract

The present invention relates to an electrochemical device and an electronic device including the same. The present invention relates to an electrochemical device including an electrode and an electrolyte, wherein the electrode includes a current collector, an active material layer located on at least one surface of the current collector, a tab located on the current collector, and a tab protection layer located on the tab, the tab protection layer including a first polymer layer, and the first polymer layer has a melting point T A °C, 110≦T A ≦136.5, the electrolyte solution contains ethylene carbonate and propylene carbonate, and based on the weight of the electrolyte solution, the sum of the weight fraction of the ethylene carbonate and the weight fraction of the propylene carbonate is Y%, Y is 20 to 80, and Y and T A is 0.147 <Y / T A The electrochemical device of the present invention has improved hot box performance and high temperature storage characteristics.

Description

[Technical Field]

[0001] The present invention relates to the field of energy storage, and more specifically to electrochemical devices and electronic devices including them, in particular to lithium-ion batteries. [Background technology]

[0002] With the proliferation and application of smart products, the demand for electronic products such as mobile phones, laptops, and cameras is increasing year by year. Electrochemical devices like lithium-ion batteries, with their high energy density, lack of memory effect, and high operating voltage, are gradually replacing traditional Ni-Cd and MH-Ni batteries as power sources for electronic products. However, with the development of lighter, thinner, and more portable electronic products, the demand for lithium-ion batteries is increasing, and the development of safe lithium-ion batteries with good cycle stability, low impedance, and low self-discharge has become one of the main market demands. [Overview of the project]

[0003] Embodiments of the present invention provide an electrochemical apparatus that attempts to solve, at least to some extent, one of the problems present in the related field. Embodiments of the present invention further provide an electronic apparatus including the electrochemical apparatus.

[0004] In one embodiment, the present invention provides an electrochemical apparatus comprising an electrode and an electrolyte.

[0005] In one embodiment, the electrode includes a current collector, an active material layer located on at least one surface of the current collector, a tab located on the current collector, and a tab protective layer located on the tab. The tab protective layer includes a first polymer layer, the melting point T of the first polymer layer A °C is 110 ≤ T A It satisfies ≤ 136.5.

[0006] In one embodiment, the electrolyte contains ethylene carbonate and propylene carbonate. Here, based on the weight of the electrolyte, the sum of the weight fraction of ethylene carbonate and the weight fraction of propylene carbonate is Y%, where Y is from 20 to 80, and Y and T A satisfy 0.147 < Y / T A < 0.7.

[0007] In some embodiments, the tab protection layer further includes a second polymer layer, and the melting point T B °C of the second polymer layer satisfies T B ≤ 160, and T A and T B satisfy 0 < T B - T A ≤ 50.

[0008] In some embodiments, the first polymer layer includes at least one of maleic anhydride graft-modified polypropylene, carboxyl group-containing polyolefin resin, and polyethylene.

[0009] In some embodiments, the second polymer layer includes at least one of polypropylene and polypropylene modified resin.

[0010] In some embodiments, the electrolyte further contains a propionate. Here, based on the weight of the electrolyte, the weight fraction of the propionate is 10% - 60%.

[0011] In some embodiments, the propionate includes at least one of methyl propionate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl fluoropropionate, ethyl fluoropropionate, propyl fluoropropionate, butyl fluoropropionate, and pentyl fluoropropionate, where "fluoro" means that at least one hydrogen atom is substituted by a fluorine atom.

[0012] In some embodiments, the electrolyte further comprises a trimethylacetate compound.

[0013] In some examples, the structural formula of the trimethylacetate compound is: [ka] And, Here, R is C1~C 10 Alkyl, C2~C 10 Alkenyl, C1~C 10 Haloalkyl, C2~C 10 They are haloalkenyls, halogens, aryls, or amides.

[0014] In some examples, the trimethylacetate compound comprises at least one of methyl trimethylacetate and ethyl trimethylacetate.

[0015] In some embodiments, the electrolyte further comprises at least one of a dinitrile compound and a trinitrile compound. Here, the dinitrile compound is Further comprising at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanooctane, 1,9-dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, and ethylene glycol bis(propionitrile) ether, The aforementioned trinitrile compound is The present invention further comprises at least one of the following: 1,3,5-pentanetricarbonitrate, 1,2,3-propanetricarbonitrate, 1,2,6-hexanetricarbonitrate, 1,3,6-hexanetricarbonitrate, 1,2,3-tri(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, and 1,2,5-tris(cyanoethoxy)pentane.

[0016] In another embodiment, the present invention provides an electronic apparatus including an electrochemical apparatus described in an embodiment of the present invention.

[0017] The electrochemical apparatus provided by the present invention has improved hot box performance and high-temperature storage characteristics.

[0018] Further aspects and advantages of embodiments of the present invention are described / represented in the following description or construed by the implementation of embodiments of the present invention. [Brief explanation of the drawing]

[0019] To facilitate the description of embodiments of the present invention, the accompanying drawings necessary to illustrate embodiments of the present invention or the prior art will be briefly described below. Clearly, the accompanying drawings in the following description represent only a portion of embodiments of the present invention. Those skilled in the art can still obtain drawings of other embodiments based on the structures illustrated in these drawings, assuming no creative effort is required. [Figure 1] Figure 1 shows a package structure of a tab and packaging bag in one embodiment of the present invention. [Figure 2] Figure 2 shows the structure of the tab protective layer in one embodiment of the present invention. [Figure 3] Figure 3 shows the structure of the tab protective layer in another embodiment of the present invention. [Figure 4] Figure 4 shows the battery structure and the position of the tab protective layer in one embodiment of the present invention. [Modes for carrying out the invention]

[0020] Examples of the present invention are described in detail below. These examples should not be construed as limiting the present invention.

[0021] In this specification, quantities, ratios, and other numerical values ​​may be expressed in range form. It should be understood that such range forms are used for convenience and conciseness. Furthermore, it should be flexibly understood that they include not only the numerical values ​​explicitly designated as range limits, but also all individual numerical values ​​or subranges that fall within that range, as explicitly specified for each numerical value and subrange.

[0022] In specific embodiments and within the scope of the claims, a list of items connected by the terms “one of,” “one of,” “one kind of,” or other similar terms means any of the listed items. For example, if items A and B are listed, the phrase “one of A and B” means either A only or B only. In other examples, if items A, B, and C are listed, the phrase “one of A, B, and C” means either A only, B only, or C only. Item A may contain one or more elements. Item B may contain one or more elements. Item C may contain one or more elements.

[0023] In specific embodiments and within the scope of the claims, a list of terms connected by the terms “at least one of,” “at least one of,” “at least one kind of,” or other similar terms means any combination of the listed terms. For example, if terms A and B are listed, the phrase “at least one of A and B” means A only, B only, or A and B. In other examples, if terms A, B, and C are listed, the phrase “at least one of A, B, and C” means A only, or B only, C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or all of A, B, and C. Term A may contain one or more elements. Term B may contain one or more elements. Term C may contain one or more elements.

[0024] As used herein, the term “alkyl” is expected to refer to a linear saturated hydrocarbon structure having 1 to 20 carbon atoms. It is also expected to refer to a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. For example, an alkyl group may be an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkyl group having 5 to 20 carbon atoms, an alkyl group having 5 to 15 carbon atoms, or an alkyl group having 5 to 10 carbon atoms. When an alkyl group having a specific number of carbon atoms is specified, it is expected that all geometric isomers having that number of carbon atoms are included. Therefore, for example, “butyl” means including n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl, and “propyl” means including n-propyl, isopropyl, and cyclopropyl. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, and norbonyl. Furthermore, alkyl groups may be optionally substituted.

[0025] As used herein, the term “alkenyl” means a monovalent unsaturated hydrocarbon group that may be linear or branched and has at least one, usually one, two, or three carbon-carbon double bonds. Unless otherwise defined, the alkenyl group generally contains 2 to 20 carbon atoms, and may be, for example, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. Typical alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-buta-2-enyl, buta-3-enyl, and n-hexa-3-enyl. The alkenyl group may also be optionally substituted.

[0026] As used herein, the term “aryl” includes monocyclic and polycyclic systems. A polycyclic system may have two or more rings in which two adjacent rings share two carbon atoms (the rings are “condensed”), where at least one of the rings is aromatic, and the other rings may be, for example, cycloalkyl, cycloalkenyl, aryl, heterocyclic, and / or heteroaryl. For example, an aryl group may be C6~C 50 Aryl group, C6~C 40 Aryl group, C6~C 30 Aryl group, C6~C 20 Aryl group, or C6~C 10 It can be an aryl group. Typical aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphthalen-1-yl, naphthalen-2-yl, etc. The aryl group may also be optionally substituted.

[0027] As used herein, the term “haloalkyl” means an alkyl group in which at least one hydrogen atom is substituted with a halogen atom. The term “haloalkenyl” means an alkenyl group in which at least one hydrogen atom is substituted with a halogen atom.

[0028] As used herein, the term "halogen" includes F, Cl, Br, and I.

[0029] When the above substituents are substituted, each substituent can be independently selected from the group consisting of halogens, alkyls, alkenyls, and aryls. As used herein, the content of each component is obtained based on the weight of the electrolyte.

[0030] As used herein, the terms “substituted” or “substituted” mean that a molecule may be substituted with one or more substituents (e.g., two, three). For example, “fluoro” means that a molecule may be substituted with one or more substituents (e.g., two, three) of F.

[0031] [1. Electrochemical apparatus] In some embodiments, the present invention provides an electrochemical apparatus comprising electrodes and an electrolyte.

[0032] In some embodiments, the electrode includes a current collector, an active material layer located on at least one surface of the current collector, a tab located on the current collector, and a tab protective layer located on the tab, wherein the tab protective layer includes a first polymer layer, and the melting point T of the first polymer layer A °C is 110 ≤ T A It satisfies ≤ 136.5.

[0033] In some embodiments, the electrolyte comprises ethylene carbonate and propylene carbonate, where, based on the weight of the electrolyte, the sum of the weight fractions of ethylene carbonate and propylene carbonate is Y%, where Y is between 20 and 80, and Y and T A is 0.147 <Y / T A Satisfy <0.7. Y / T A Being within this range improves the thermal stability of the electrochemical system in electrochemical equipment, further enhances hot box performance, and significantly improves the high-temperature storage characteristics of lithium-ion batteries.

[0034] In some embodiments, T A It is 110, 115, 120, 125, 130, 135, 136, or 136.5, or within the range of any two of these numbers. A Being within this range significantly improves the safety of electrochemical equipment.

[0035] In some embodiments, Y is 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, or 80, or within the range of any two of these numbers.

[0036] In some embodiments, Y / T AThe value is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.65, or 0.7, or within the range of any two of these numbers.

[0037] In some embodiments, the tab protective layer further comprises a second polymer layer, wherein the melting point T of the second polymer layer B ℃ is T B Satisfying ≤ 160, and T A and T B is, 0 <T B -T A Satisfying ≤ 60. B -T A Being within this range provides electrochemical equipment with superior safety.

[0038] In some embodiments, T B The value is 138, 140, 145, 150, 155, or 160, or within the range of any two of these numbers.

[0039] In some embodiments, T B -T A The value is 0.1, 0.5, 1, 3, 5, 10, 20, 30, 40, or 50, or within the range of any two of these numbers.

[0040] In some examples, the first polymer layer comprises at least one of maleic anhydride graft-modified polypropylene, carboxyl group-containing polyolefin resin, and polyethylene.

[0041] In some embodiments, the first polymer layer includes at least one of the following: Mitsui Chemicals' QE840, QFF551, DuPont's Nucrel 0910, DuPont's Elvax, Samsung's E093A, and Mitsubishi Chemical's P546.

[0042] In some embodiments, the second polymer layer comprises at least one polypropylene resin.

[0043] In some embodiments, the second polymer layer includes at least one of Samsung's CF330, TPC's FS5611, and ExxonMobil's 6102FL.

[0044] In some embodiments, the tab protective layer has a single-layer, double-layer, or triple-layer structure.

[0045] In some embodiments, the tab protective layer consists of one first polymer layer. In some embodiments, the tab protective layer consists of one first polymer layer and one second polymer layer. In some embodiments, the tab protective layer consists of two first polymer layers and one second polymer layer located between the two first polymer layers.

[0046] In some embodiments, the electrolyte further comprises a propionic acid ester, where the weight fraction of the propionic acid ester is 10% to 60% based on the weight of the electrolyte. In some embodiments, the weight fraction of the propionic acid ester is 10%, 20%, 30%, 40%, 50%, or 60% based on the weight of the electrolyte, or within a range of any two of these values.

[0047] In some examples, the propionic acid ester comprises at least one of methyl propionate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl fluoropropionate, ethyl fluoropropionate, propyl fluoropropionate, butyl fluoropropionate, and pentyl fluoropropionate, where fluoro means that at least one hydrogen atom is substituted with a fluorine atom.

[0048] In some embodiments, the electrolyte further comprises a trimethylacetate compound.

[0049] In some examples, the structural formula of the trimethylacetate compound is: [ka] And, Here, R is C1~C 10 Alkyl, C2~C 10 Alkenyl, C1~C 10 Haloalkyl, C2~C 10 They are haloalkenyls, halogens, aryls, or amides.

[0050] In some examples, R is a C1-C6 alkyl, C2-C6 alkenyl, C1-C6 haloalkyl, C2-C6 haloalkenyl, halogen, aryl, or amide.

[0051] In some examples, the trimethylacetate compound comprises at least one of methyl trimethylacetate and ethyl trimethylacetate.

[0052] In some embodiments, the electrolyte further comprises at least one of a dinitrile compound and a trinitrile compound. Here, the dinitrile compound is Further comprising at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanooctane, 1,9-dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, and ethylene glycol bis(propionitrile) ether, The aforementioned trinitrile compound is The present invention further comprises at least one of the following: 1,3,5-pentanetricarbonitrate, 1,2,3-propanetricarbonitrate, 1,2,6-hexanetricarbonitrate, 1,3,6-hexanetricarbonitrate, 1,2,3-tri(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, and 1,2,5-tris(cyanoethoxy)pentane.

[0053] In some examples, the content of the dinitrile compound is 1% to 5% based on the weight of the electrolyte. In some examples, the content of the dinitrile compound is 1%, 2%, 3%, 3.5%, 4.0%, or 5.0% based on the weight of the electrolyte, or within a range of any two of these values.

[0054] In some examples, the content of the trinitrile compound is 1% to 5% based on the weight of the electrolyte. In some examples, the content of the trinitrile compound is 1%, 2%, 3%, 3.5%, 4.0%, 5.0%, or 6.0% based on the weight of the electrolyte, or within a range of any two of these values.

[0055] In some embodiments, the electrolyte comprises a trinitrile compound and ethylene glycol bis(propionitrile) ether, and based on the weight of the electrolyte, the weight fraction of the trinitrile compound is a%, the content of the ethylene glycol bis(propionitrile) ether is b%, and the condition 1.0 ≤ a + b ≤ 6.0 is satisfied. In some embodiments, a + b is 1.0, 2.0, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0, or within the range of any two of these values.

[0056] In some embodiments, 1.2 ≤ a / b ≤ 20. In some embodiments, a / b is 2.0, 3.0, 3.3, 4.0, 5.5, 7.0, 8.5, 9.5, 12.0, 14.5, 16.5, 18.5, or 20.0, or within the range of any two of these values.

[0057] In some embodiments, the electrolyte further comprises fluoroethylene carbonate and 1,3-propanesultone, where, based on the weight of the electrolyte, the weight fraction of fluoroethylene carbonate is c%, the weight fraction of 1,3-propanesultone is d%, and the condition 6.0 ≤ c + d ≤ 15.0 is satisfied. In some embodiments, c + d is within the range of 6.0, 7.0, 8.0, 8.5, 9.0, 9.5, 10.0, 11.0, 11.5, 12.0, 13.0, 14.0, or 15.0, or any two of these values.

[0058] In some embodiments, 1.2 ≤ c / d ≤ 20. In some embodiments, c / d is 1.2, 2.0, 3.0, 3.3, 4.0, 5.5, 7.0, 8.5, 9.5, 12.0, 14.5, 16.5, 18.5, or 20.0, or within the range of any two of these values.

[0059] In some embodiments, the electrolyte may further contain allylnitrile.

[0060] In some embodiments, the electrochemical apparatus includes any apparatus in which an electrochemical reaction occurs.

[0061] In some embodiments, the electrode includes a negative electrode having a negative electrode active material capable of intercepting and releasing metal ions, and a positive electrode having a positive electrode active material capable of intercepting and releasing metal ions.

[0062] In some embodiments, the electrochemical apparatus further includes a separator located between the positive electrode and the negative electrode.

[0063] In some embodiments, the electrochemical apparatus is a lithium secondary battery.

[0064] In some embodiments, the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery or an all-solid-state lithium secondary battery.

[0065] Figure 1 shows a package structure of a tab and a packaging bag in one embodiment of the present invention. Packaging bag 1-1 is bonded to a metal tape 1-3 by a tab protective layer 1-2, and packaging bag 1-5 is bonded to a metal tape 1-3 by a tab protective layer 1-4, where both tab protective layers 1-2 and 1-4 are single-layer structures, i.e., consist of one first polymer layer.

[0066] Figure 2 shows the structure of a tab protection layer in one embodiment of the present invention. The tab protection layer has a two-layer structure, where the tab protection layer located above the metal tape 2-3 consists of a first polymer layer 2-1 and a second polymer layer 2-2, and the tab protection layer located below the metal tape 2-3 consists of a first polymer layer 2-5 and a second polymer layer 2-4.

[0067] Figure 3 shows the structure of a tab protection layer in another embodiment of the present invention. This tab protection layer has a three-layer structure. The tab protection layer located above the metal tape 3-4 consists of first polymer layers 3-1 and 3-3 and a second polymer layer 3-2 located between them. The tab protection layer located below the metal tape 3-4 consists of first polymer layers 3-5 and 3-6 and a second polymer layer 3-6 located between them.

[0068] The primary role of the tab protection layer is to adhere to the tabs of the lithium-ion battery so that the tabs are heat-sealed to the polypropylene layer on the inside of the polymer battery packaging bag. Currently, commonly used tab protection layers generally have a melting point of 140°C or higher, but the present invention primarily aims to improve the thermal safety of the battery by using a tab protection layer with a lower melting point, thereby allowing the battery to dissipate heat more quickly.

[0069] negative electrode The materials, configuration, and method for manufacturing the negative electrode used in the electrochemical apparatus of the present invention may include techniques disclosed in any prior art. In some embodiments, the negative electrode is the negative electrode described in U.S. Patent Application US9812739B, which is incorporated into the present invention by reference in its entirety.

[0070] In some embodiments, the negative electrode includes a current collector and a negative electrode active material layer located on the current collector. In some embodiments, the negative electrode active material layer includes a negative electrode active material. In some embodiments, the negative electrode active material is lithium metal, structured lithium metal, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, silicon oxide material, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, spinel-structured lithium TiO2-Li4Ti5O 12 This includes, but is not limited to, Li-Al alloys, or any combination thereof.

[0071] In some examples, the negative electrode active material layer includes a binder. In some examples, the binder includes, but is not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, or nylon.

[0072] In some embodiments, the negative electrode active material layer includes a conductive material. In some embodiments, the conductive material includes, but is not limited to, natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fibers, metal powders, metal fibers, copper, nickel, aluminum, silver, or polyphenylene derivatives.

[0073] In some embodiments, the current collector includes, but is not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal.

[0074] In some embodiments, the negative electrode can be obtained by preparing an active material composition by mixing an active material, a conductive material, and a binder in a solvent, and then coating the active material composition onto a current collector.

[0075] In some examples, the solvent may include, but is not limited to, deionized water and N-methylpyrrolidone.

[0076] In some embodiments, the negative electrode in an all-solid-state lithium secondary battery is a metallic lithium foil.

[0077] positive electrode The materials for the cathode used in the electrochemical apparatus of the present invention can be prepared using materials, structures, and manufacturing methods known in the art. In some embodiments, the cathode of the present invention can be prepared using the technique described in U.S. Patent Application US9812739B, which is incorporated into the present invention by reference in its entirety.

[0078] In some embodiments, the positive electrode comprises a current collector and a positive electrode active material layer located on the current collector. The positive electrode active material comprises at least one lithiation intercalation compound that reversibly intercalates and releases lithium ions. In some embodiments, the positive electrode active material comprises a composite oxide. In some embodiments, the composite oxide comprises lithium and at least one element selected from cobalt, manganese, and nickel.

[0079] In some embodiments, the positive electrode active material is selected from lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese (NCM) ternary materials, lithium ferrous phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), and any combination thereof.

[0080] In some embodiments, the positive electrode active material may have a coating on its surface or may be mixed with another compound having a coating. The coating may comprise at least one coating element compound selected from oxides of the coating element, hydroxides of the coating element, hydroxyoxides of the coating element, carbonates of the coating element, and hydroxycarbonates of the coating element. The compounds used for the coating may be amorphous or crystalline.

[0081] In some embodiments, the coating elements included in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, F, or any combination thereof. The coating can be applied by any method, provided that the method does not adversely affect the performance of the positive electrode active material. For example, the method may include any coating method known in the art, such as spraying or dipping.

[0082] The positive electrode active material layer further contains a binder and may optionally contain a conductive material. The binder improves the bonding between the positive electrode active material particles and also improves the bonding between the positive electrode active material and the current collector.

[0083] In some examples, the binder includes, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, nylon, and the like.

[0084] In some embodiments, the conductive material includes, but is not limited to, carbon-based materials, metallic materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and any combination thereof. In some embodiments, the metallic material is selected from metal powders, metal fibers, copper, nickel, aluminum, and silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0085] In some embodiments, the current collector may be made of aluminum, but is not limited thereto.

[0086] The positive electrode can be prepared by preparation methods known in the art. For example, the positive electrode can be obtained by preparing an active material composition by mixing an active material, a conductive material, and a binder in a solvent, and then coating the active material composition onto a current collector. In some examples, the solvent may include, but is not limited to, N-methylpyrrolidone.

[0087] In some embodiments, the positive electrode is fabricated by forming a positive electrode material on a current collector using a positive electrode active material layer containing lithium transition metal compound powder and a binder.

[0088] In some embodiments, the positive electrode active material layer can typically be prepared by dry-mixing the positive electrode material with a binder (such as a conductive material and a thickener as needed) to form a sheet, and then pressing the resulting sheet onto the positive electrode current collector; or by dissolving or dispersing these materials in a liquid medium to form a slurry, applying it to the positive electrode current collector, and drying it. In some embodiments, the material of the positive electrode active material layer includes any material known in the art.

[0089] Separator In some embodiments, the electrochemical apparatus of the present invention includes a separator between the positive and negative electrodes to prevent short circuits. The material and shape of the separator used in the electrochemical apparatus of the present invention are not particularly limited and may be any material and shape disclosed in the prior art. In some embodiments, the separator includes a polymer or inorganic material formed from a material stable in the electrolyte of the present invention.

[0090] For example, a separator may include a base layer and a surface treatment layer. The base layer is a nonwoven fabric, membrane, or composite membrane having a porous structure, and the material of the base layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected and used.

[0091] A surface treatment layer is provided on at least one surface of the substrate layer. The surface treatment layer may be a polymer layer or an inorganic layer, or it may be a layer formed by mixing a polymer and an inorganic material.

[0092] The inorganic layer comprises inorganic particles and a binder, the inorganic particles being selected from one or more combinations of alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is selected from one or more combinations of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The polymer layer contains a polymer, and the polymer material includes at least one of the following: polyamide, polyacrylonitrile, acrylic acid ester polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0093] electrolyte The electrolyte used in the electrolyte of the embodiment of the present invention may be an electrolyte known in the prior art. Examples of electrolytes include inorganic lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiSbF6, LiSO3F, LiN(FSO2)2; LiCF3SO3, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,3-hexafluoropropane bissulfonyliimide lithium, cyclic 1,2-tetrafluoroethane bissulfonyliimide lithium, LiN(CF3SO2)(C4F9SO2), LiC(CF3SO2)3, LiPF4(CF3)2, LiPF4(C2F5)2, L The electrolytes include, but are not limited to, fluorine-containing organolithium salts such as iPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2; and dicarboxylic acid complex-containing lithium salts such as lithium bis(oxalate) borate, lithium difluorooxalate borate, lithium tris(oxalate) phosphate, lithium difluorobis(oxalate) phosphate, and lithium tetrafluoro(oxalate) phosphate. Furthermore, the electrolytes may be used individually or in combination of two or more. For example, in some examples, the electrolyte includes a combination of LiPF6 and LiBF4. In some examples, the electrolyte includes a combination of an inorganic lithium salt such as LiPF6 or LiBF4 and a fluorine-containing organolithium salt such as LiCF3SO3, LiN(CF3SO2)2, and LiN(C2F5SO2)2. In some examples, the electrolyte concentration is in the range of 0.8 to 3 mol / L, for example, in the range of 0.8 to 2.5 mol / L, 0.8 to 2 mol / L, 1 to 2 mol / L, 0.5 to 1.5 mol / L, 0.8 to 1.3 mol / L, 0.5 to 1.2 mol / L, and also, for example, 1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.5 mol / L, 2 mol / L, or 2.5 mol / L.

[0094] [Second, electronic equipment] The electronic device of the present invention may be any device that uses the electrochemical apparatus according to the embodiment of the present invention.

[0095] In some embodiments, the electronic devices include, but are not limited to, laptop computers, pen-input computers, mobile computers, e-book players, mobile phones, portable facsimile machines, portable copiers, portable printers, stereo headsets, video recorders, LCD televisions, portable cleaners, portable CD players, MiniDiscs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric assist bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors.

[0096] In the following, we will use lithium-ion batteries as an example and explain the preparation of lithium-ion batteries with reference to specific examples. Those skilled in the art should understand that the preparation methods described in this invention are merely illustrative, and any other suitable preparation methods fall within the scope of this invention.

[0097] <Examples> The performance of the lithium-ion battery of the present invention will be evaluated below based on examples and comparative examples.

[0098] [1. Preparation of Lithium-ion Batteries] (1) Preparation of the electrolyte In an argon-atmosphered glove box with a water content of <10 ppm, ethylene carbonate (EC), propylene carbonate (PC), and other organic solvents were mixed in fixed proportions. The other organic solvents were selected from at least one of diethyl carbonate (DEC), ethyl propionate (EP), and propyl propionate (PP). Then, LiPF6 was added and the mixture was uniformly stirred to form a basic electrolyte, where the concentration of LiPF6 was 1.15 mol / L. Different examples and comparative examples of electrolytes were obtained by adding substances with different content, as shown in the following tables, to the basic electrolyte. The content of each substance in the electrolytes described in this invention was calculated based on the weight of the electrolyte. The EC and PC content in Table 1 is shown in the table, and the remaining organic solvent is DEC.

[0099] (2) Preparation of the positive electrode Lithium cobalt oxide (LiCoO2), the positive electrode active material, carbon nanotubes (CNT), the conductive agent, and polyvinylidene fluoride, the binder, were mixed in a weight ratio of 95:2:3. N-methylpyrrolidone (NMP) was added, and the mixture was stirred using a vacuum stirrer until the system was homogeneous to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated onto aluminum foil, which was the positive electrode current collector, dried at 85°C, then cold-pressed, sliced, and cut, and finally dried under vacuum conditions at 85°C for 4 hours to obtain the positive electrode.

[0100] (3) Preparation of the negative electrode The negative electrode active material, graphite, the binder, styrene-butadiene rubber (SBR), and the thickener, sodium carboxymethylcellulose (CMC), were thoroughly mixed in an appropriate amount of deionized water solvent in a weight ratio of 95:2:3 to form a uniform negative electrode slurry. This slurry was then coated onto a Cu foil, which served as the negative electrode current collector, dried, and cold-pressed to obtain the negative electrode.

[0101] (4) Preparation of separators A polyethylene (PE) diaphragm was selected as the separator.

[0102] (5) Preparation of lithium-ion batteries Using plate heating or high-frequency heating, a tab protective layer and a metal tape were combined to create a tab containing the tab protective layer, and this tab was fixed to the positive and negative electrodes by welding. The positive electrode, separator, and negative electrode were stacked in order, with the separator positioned between the positive and negative electrodes to separate them. Then, the assembly was wound, placed in an outer foil, and the electrolyte prepared above was injected into the dried battery. After going through processes such as vacuum packaging, settling, formation, and shaping, the preparation of the lithium-ion battery was completed.

[0103] [2.Measurement method] 1. Hotbox testing: At 25°C, lithium-ion batteries were charged to 4.45V with a constant current of 0.7C, and then further charged with a constant voltage of 4.45V until the current reached 0.05C. The batteries were placed in a hot box and heated to 135°C at a heating rate of 5±2°C / min, held for 1 hour (hr), and the changes in battery voltage, temperature, and hot box temperature were recorded. The test was passed if no fire or explosion occurred. Ten batteries were tested per set, and the number of batteries that passed the test was recorded.

[0104] 2. High-temperature storage test: The lithium-ion battery was left standing at 25°C for 30 minutes. Then, it was charged with a constant current at a rate of 0.5C up to 4.45V, and then charged with a constant voltage at 4.45V down to 0.05C, left standing for 5 minutes, and the thickness of the lithium-ion battery was measured and recorded as h0. After that, the lithium-ion battery was stored in a constant temperature box at 85°C for 24 days, and the thickness of the lithium-ion battery was measured and recorded as h1. The thickness expansion rate of the lithium-ion battery was calculated using the following formula: Thickness expansion rate (%) = (h1 - h0) / h0 × 100%.

[0105] 3. Low-temperature discharge test At 25°C, lithium-ion batteries were charged to 4.45V with a constant current of 0.7C, and then charged again with a constant voltage of 4.45V until the current dropped to 0.05C. Afterward, the lithium-ion batteries were left to stand for 4 hours at different temperatures (25°C, 0°C, and -10°C), and then discharged to 3.0V at 0.2C. After each discharge, the batteries were left to stand for an additional 5 minutes, and the discharge capacity of the lithium-ion batteries was recorded. The discharge capacity at 25°C was used as the baseline to obtain the ratio of the discharge capacities of the lithium-ion batteries at different temperatures. Discharge capacity ratio (%) of lithium-ion batteries at different temperatures = Discharge capacity at different temperatures (0°C, -10°C) / Discharge capacity at 25°C × 100%

[0106] 4. High-temperature storage test At 25°C, the lithium-ion battery was left standing for 30 minutes, then charged with a constant current at a rate of 0.5C up to 4.45V, and further charged with a constant voltage at 4.45V down to 0.05C, left standing for 5 minutes, and then stored at 85°C for 24 days. After that, the thickness of the battery was measured, and the thickness expansion rate of the battery was calculated using the following formula. Thickness expansion rate = [(Thickness after storage - Thickness before storage) / Thickness before storage] × 100%.

[0107] A. Table 1 shows the composition and performance test results of lithium-ion batteries in the relevant examples. Here, the tab protective layer used in Comparative Examples D1-1 to D1-2 consists of one second polymer layer, and its melting point is T B The second polymer layer is selected from Samsung's CF330 block copolymer polypropylene. The tab protective layer used in Comparative Examples D1-3 to D1-5 and Examples S1-1 to S1-7 consists of one first polymer layer, and its melting point is T A The first polymer layer is made of Bynel 50E632 (melting point 136.5 o C) Bynel 50E631 (melting point 136°C) o C), Bynel 40E529 (melting point 135°C) o C), Bynel 50E662 (melting point 130°C) o C), Bynel 4104 (melting point 125°C) oC), Bynel 4208 (melting point 110°C) o C), Nucrel 0910 (melting point 100°C) o Selected from C).

[0108] [Table 1]

[0109] As can be seen from the test results in Table 1, the lithium-ion batteries of Comparative Examples D1-1 and D1-2 could only pass the 130°C hot box test, and the pass rates for the 132°C and 135°C hot box tests were both low. This is because the melting points of the tab protection layer of Comparative Examples D1-1 and D1-2 are relatively high, so during abuse tests such as hot box tests, the gas bag cannot be opened in a timely manner, the generated heat gradually accumulates inside the battery, and the battery is very likely to ignite, burn, and even explode. Adjusting the total amount of EC+PC or adjusting the melting point of the polymer layer has a clear effect on hot box performance, but if the EC+PC content is low, adjusting the melting point does not yield good results. On the other hand, if the EC+PC content is high, adjusting the melting point is effective for hot box performance, but the electrical performance is relatively poor, so both can only be effective within a certain reasonable usage amount.

[0110] As can be seen from the test results of Examples S1-1 to S1-11, the tab protective layer prepared from the second polymer layer was replaced with the tab protective layer prepared from the first polymer layer, and the melting point value T of the first polymer layer was also changed. A The difference between this value and the EC+PC content value Y is 0.147 <Y / T AWhen the value <0.7 is met, the pass rate of the lithium-ion battery's hot box test is significantly improved. On the one hand, by introducing a first polymer layer into the tab protective layer, the gas inside the battery can open the gas bag earlier, and heat is released in a timely manner, thus clearly improving the hot box test. On the other hand, by improving the thermal stability of the entire electrochemical system, the hot box performance is further improved, and the high-temperature storage characteristics of the lithium-ion battery can be significantly enhanced.

[0111] Tables B, 2, and 3 show the composition and performance test results of lithium-ion batteries in the relevant examples. Here, the tab protective layer in Examples S2-1 to S2-3 has a two-layer structure, comprising one first polymer layer and one second polymer layer. The tab protective layer in Example S3-1 has a three-layer structure, i.e., comprising one second polymer layer between two first polymer layers, and the melting point value T of the first polymer layer. A Both temperatures were 125°C. The first polymer layer was selected from Bynel 4104 (125°C), and the second polymer layer was selected from Samsung's CF330 block copolymer polypropylene.

[0112] [Table 2]

[0113] [Table 3]

[0114] As can be seen from the test results in Tables 2 and 3, the performance of the lithium-ion battery in the hot box test can be similarly improved by replacing the tab protection layer prepared from the second polymer layer in Comparative Example D1-2 with the two-layer and three-layer tab protection layers described above. This is because, whether it is a two-layer or three-layer structure, if a low-melting-point layer is included, heat can be released from the battery in a timely manner even at low temperatures, preventing thermal runaway of the battery.

[0115] Table 4 shows the composition of lithium-ion batteries in the relevant examples and the results of performance tests. The preparation of lithium-ion batteries in Examples S4-1 and S4-2 is the same as in Examples S1 and S2, except for the difference in electrolyte composition, which is shown in detail in Table 4.

[0116] [Table 4]

[0117] As can be seen from the test results in Table 4, the melting point T of the first polymer layer A The difference between the EC+PC content Y and 0.147 <Y / T A If the condition <0.7 is met, the low-temperature performance of the lithium-ion battery can be further improved by adding a certain amount of at least one of propyl propionate or ethyl propionate to the electrolyte.

[0118] Table 5 shows the composition of lithium-ion batteries and the results of performance tests in the relevant examples. The preparation process of lithium-ion batteries in Examples S5-1 to S5-3 is the same as in Example S1-2, except for the difference in electrolyte composition, which is shown in detail in Table 5.

[0119] [Table 5] As can be seen from the test results in Table 5, the melting point T of the first polymer layer A The difference between the EC+PC content Y and 0.147 <Y / T A If the value <0.7 is met, the hot-box performance of the lithium-ion battery can be further improved by adding a certain amount of trimethylacetate to the electrolyte.

[0120] Table 6 shows the composition of lithium-ion batteries in the relevant examples and the results of performance tests. The preparation process of lithium-ion batteries in Examples S6-1 to S6-16 is the same as in Example S1-2, except for the difference in electrolyte composition, which is shown in detail in Table 6.

[0121] [Table 6] As can be seen from the test results in Table 6, the melting point T of the first polymer layer A The difference between the EC+PC content Y and 0.147 <Y / T A If the condition <0.7 is met, the hot-box performance of the lithium-ion battery can be further improved by adding a certain amount of dinitrile and trinitrile compounds to the electrolyte.

[0122] Table 7 shows the composition of lithium-ion batteries and the results of performance tests in the relevant examples. The preparation process of lithium-ion batteries in Examples S7-1 to S7-11 is the same as in Example S1-2, except for the difference in electrolyte composition, which is shown in detail in Table 7.

[0123] [Table 7]

[0124] As can be seen from the test results in Table 7, the melting point T of the first polymer layer A The difference between the EC+PC content Y and 0.147 <Y / T A When the value <0.7 is satisfied, adding a certain amount of fluoroethylene carbonate to the electrolyte causes a certain degree of deterioration in the battery's hot box performance. Adding 1,3-propanesultone does not have a significant effect on the hot box performance. However, when both are present simultaneously, the hot box performance of the lithium-ion battery can be further improved, which is presumed to be related to film formation caused by their combined use. When both are present simultaneously, the optimal effect can be obtained by adding a dinitrile compound and a trinitrile compound at the same time.

[0125] Throughout this specification, any reference using phrases such as “several examples,” “part of an example,” “one example,” “another example,” “example,” “specific example,” or “part of an example” means that at least one example of the present invention includes the specific features, structures, materials, or properties described in that example. Therefore, any other reference to “in several examples,” “in an example,” “in one example,” “in another example,” “in one example,” “in a particular example,” or “example” throughout this specification does not necessarily refer to the same example of the present invention. Furthermore, the specific features, structures, materials, or properties described herein can be combined in any preferred manner in one or more examples.

[0126] Although exemplary embodiments have been described and explained, those skilled in the art should understand that the above embodiments are not intended to limit the present invention, and that modifications, substitutions, and changes to the embodiments are permitted as long as they do not depart from the technical spirit, principles, and scope of the present invention.

Claims

1. An electrochemical apparatus comprising electrodes and an electrolyte, The electrode includes a current collector, an active material layer located on at least one surface of the current collector, a tab located on the current collector, and a tab protective layer located on the tab. The tab protective layer includes a first polymer layer, Melting point T of the first polymer layer Ａ °C is 110 ≤ T Ａ Satisfying ≤ 136.5, The electrolyte comprises ethylene carbonate and propylene carbonate. Based on the weight of the electrolyte, when the sum of the weight fractions of ethylene carbonate and propylene carbonate is Y%, Y is between 20 and 80, and, Y and T Ａ is 0.147 < Y / T Ａ < Satisfying 0.7, The electrolyte further comprises fluoroethylene carbonate and 1,3-propanesultone, and based on the weight of the electrolyte, when the weight fraction of fluoroethylene carbonate is c% and the weight fraction of 1,3-propanesultone is d%, c and d are an electrochemical apparatus satisfying 7.0 ≤ c + d ≤ 9.0 and 4 / 3 ≤ c / d ≤ 6.

2. The tab protective layer further comprises a second polymer layer, Melting point T of the second polymer layer Ｂ °C is T Ｂ The condition satisfies ≤ 160, and, T Ａ and T Ｂ where 0 < T Ｂ - T Ａ ≦ 50, the electrochemical device according to claim 1.

3. The electrochemical apparatus according to claim 1, wherein the first polymer layer comprises at least one of maleic anhydride graft-modified polypropylene, carboxyl group-containing polyolefin resin, and polyethylene.

4. The electrochemical apparatus according to claim 2, wherein the second polymer layer comprises a polypropylene resin.

5. The electrolyte further contains propionic acid ester, The electrochemical apparatus according to claim 1, wherein the weight fraction of the propionic acid ester is 10% to 60% based on the weight of the electrolyte.

6. The propionic acid ester comprises at least one of methyl propionate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, methyl fluoropropionate, ethyl fluoropropionate, propyl fluoropropionate, butyl fluoropropionate, and pentyl fluoropropionate. The electrochemical apparatus according to claim 5, wherein "fluoro" means that at least one hydrogen atom is substituted with a fluorine atom.

7. The electrochemical apparatus according to claim 1, wherein the electrolyte further comprises a trimethylacetate compound.

8. The structural formula of the aforementioned trimethylacetate compound is, 【Chemistry 1】 And, Here, R is C １ ~C １０ Alkyl, C ２ ~C １０ Alkenil, C １ ~C １０ Haloalkyl, C ２ ~C １０ The electrochemical apparatus according to claim 7, wherein the haloalkenyl is a halogen, aryl, or amide.

9. The electrochemical apparatus according to claim 7, wherein the trimethylacetate compound comprises at least one of methyl trimethylacetate and ethyl trimethylacetate.

10. The electrolyte further comprises at least one of a dinitrile compound and a trinitrile compound. The aforementioned dinitrile compound Me Further comprising at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanooctane, 1,9-dicyanononane, 1,10-dicyanodecane, 1,12-dicyanododecane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, and ethylene glycol bis(propionitrile) ether, The aforementioned trinitrile compound is The electrochemical apparatus according to claim 1, further comprising at least one of 1,3,5-pentanetricarbonitrate, 1,2,3-propanetricarbonitrate, 1,2,6-hexanetricarbonitrate, 1,3,6-hexanetricarbonitrate, 1,2,3-tri(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, and 1,2,5-tris(cyanoethoxy)pentane.

11. An electronic apparatus comprising an electrochemical apparatus as described in any one of claims 1 to 10.