Electrochemical device and electronic device including the same

Abstract

To provide an electrochemical device having an improved hot box performance and high-temperature storage characteristics.SOLUTION: The present invention relates to an electrochemical device and an electronic device including the same. The present invention provides an electrochemical device including an electrode 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, and the first polymer layer has a melting point TA°C satisfying 110≤TA≤136.5. The electrolyte contains ethylene carbonate and propylene carbonate. When, based on the weight of the electrolyte, the total of a weight fraction of the ethylene carbonate and a weight fraction of the propylene carbonate is Y%, Y is 20 to 80, and Y and TA satisfy 0.147<Y / TA<0.7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of energy storage, and in particular to electrochemical devices and electronic devices containing same, especially lithium-ion batteries. [Background technology]

[0002] With the widespread adoption and application of smart products, the demand for electronic products such as mobile phones, laptops, and cameras is increasing year by year. Electrochemical devices such as lithium-ion batteries, with their high energy density, no memory effect, and high operating voltage, are gradually replacing traditional Ni-Cd and MH-Ni batteries as the power source for electronic products. However, with the development of lighter, thinner, and more portable electronic products, the demand for lithium-ion batteries is increasing. The development of lithium-ion batteries with good cycle stability, low impedance, low self-discharge, and safety has become a major market demand. Summary of the Invention

[0003] Embodiments of the present invention provide electrochemical devices that attempt to solve, at least to some extent, at least one of the problems existing in the related art.Embodiments of the present invention also provide electronic devices that include the electrochemical devices.

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

[0005] In one embodiment, the electrode includes a current collector, an active material layer disposed on at least one surface of the current collector, a tab disposed on the current collector, and a tab protection layer disposed on the tab. The tab protection layer includes a first polymer layer having a melting point T A °C, 110≦T A ≦136.5.

[0006] In one embodiment, the electrolyte solution includes ethylene carbonate and propylene carbonate, where, 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 <0.7.

[0007] In some embodiments, the tab protection layer further comprises a second polymer layer, and the second polymer layer has a melting point T B °C is T B ≦160, and T A and T B is 0 <T B -T A Meets ≦50.

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

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

[0010] In some embodiments, the electrolyte further comprises a propionate ester, wherein the weight fraction of the propionate ester is 10% to 60% based on the weight of the electrolyte.

[0011] In some embodiments, the propionate 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 replaced with a fluorine atom.

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

[0013] In some embodiments, the trimethyl acetate compound has the structural formula: [ka] and Here, R is C1 to C 10 Alkyl, C2-C 10 Alkenyl, C1-C 10 Haloalkyl, C2-C 10 It is haloalkenyl, halogen, aryl, or amido.

[0014] In some embodiments, the trimethyl acetate compound comprises at least one of methyl trimethyl acetate and ethyl trimethyl acetate.

[0015] In some embodiments, the electrolyte further comprises at least one of a dinitrile compound and a trinitrile compound; wherein the dinitrile compound is further comprising at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 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 trinitrile compound is Further comprising at least one of 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 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 device comprising an electrochemical device according to any embodiment of the present invention.

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

[0018] Additional aspects and advantages of embodiments of the invention will be set forth in part in the description that follows, or may be learned by practice of embodiments of the invention. [Brief explanation of the drawings]

[0019] In order to facilitate the description of the embodiments of the present invention, the accompanying drawings necessary for describing the embodiments of the present invention or the prior art will be briefly described below. Obviously, the accompanying drawings in the following description are only a part of the 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 without requiring creative efforts. [Figure 1] FIG. 1 shows a package structure of a tub and a packaging bag in one embodiment of the present invention. [Figure 2] FIG. 2 shows the structure of the tab protection layer in one embodiment of the present invention. [Figure 3] FIG. 3 shows the structure of a tab protection layer in another embodiment of the present invention. [Figure 4] FIG. 4 shows the cell structure and location of the tab protection layer in one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0021] It should be noted that quantities, ratios, and other numerical values ​​may be presented in range format herein. It should be understood that such range format is used for convenience and brevity. It should also be understood with flexibility to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges contained within the range, as if each numerical value and subrange were explicitly specified.

[0022] In specific embodiments and in the claims, a list of terms connected by the terms "one of," "one of," "one of," or other similar terms means any of the listed terms. For example, if term A and term B are listed, the phrase "one of A and B" means only A or only B. In another example, if term A, term B, and term C are listed, the phrase "one of A, B, and C" means only A, only B, or only C. Term A may include a single element or multiple elements. Term B may include a single element or multiple elements. Term C may include a single element or multiple elements.

[0023] In specific embodiments and claims, a list of terms connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms refers to any combination of the listed terms. For example, if term A and term B are listed, the phrase "at least one of A and B" refers to A only, B only, or A and B. In other examples, if term A, term B, and term C are listed, the phrase "at least one of A, B, and C" refers to A only, or B only, or C only, or A and B (excluding C), or A and C (excluding B), or B and C (excluding A), or all of A, B, and C. Term A may include a single element or multiple elements. Term B may include a single element or multiple elements. Term C may include a single element or multiple elements.

[0024] As used herein, the term "alkyl" is intended to mean a linear saturated hydrocarbon structure having 1 to 20 carbon atoms. Alternatively, "alkyl" is intended to mean a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. For example, an alkyl group can 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, all geometric isomers having that number of carbon atoms are intended to be included. Thus, for example, "butyl" is intended to include n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl, and "propyl" is intended to include n-propyl, isopropyl, and cyclopropyl. Illustrative 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, norbornyl, etc. Additionally, alkyl groups may be optionally substituted.

[0025] As used herein, the term "alkenyl" refers to a monovalent unsaturated hydrocarbon group that may be straight-chained 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. Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, the alkenyl group may be optionally substituted.

[0026] As used herein, the term "aryl" includes monocyclic and polycyclic ring systems. Polycyclic rings may have two or more rings in which two adjacent rings share two carbons (the rings are "fused"), 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, aryl groups include C6-C 50 Aryl groups, C6-C 40 Aryl groups, C6-C 30 Aryl groups, C6-C 20 Aryl group or C6-C 10 It can be an aryl group. Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, naphthalen-1-yl, naphthalen-2-yl, etc. The aryl group may also be optionally substituted.

[0027] As used herein, the term "haloalkyl" refers to an alkyl group in which at least one hydrogen atom is replaced with a halogen atom. The term "haloalkenyl" refers to an alkenyl group in which at least one hydrogen atom is replaced 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 of the substituents may be independently selected from the group consisting of halogen, alkyl, alkenyl, and aryl. As used herein, the content of each component is given based on the weight of the electrolyte.

[0030] As used herein, the term "substituted" or "substituted" means that it may be substituted with one or more (e.g., two or three) substituents. For example, "fluoro" means that it may be substituted with one or more (e.g., two or three) F.

[0031] [1. Electrochemical equipment] In some embodiments, the present invention provides an electrochemical device that includes an electrode and an electrolyte.

[0032] In some embodiments, the electrode includes a current collector, an active material layer disposed on at least one surface of the current collector, a tab disposed on the current collector, and a tab protection layer disposed on the tab, the tab protection layer including a first polymer layer, the first polymer layer having a melting point T A °C, 110≦T A ≦136.5.

[0033] In some embodiments, the electrolyte solution includes ethylene carbonate and propylene carbonate, where the sum of the weight fraction of the ethylene carbonate and the weight fraction of the propylene carbonate is Y%, based on the weight of the electrolyte solution, Y is 20 to 80, and Y and T A is 0.147 <Y / T A <0.7 Y / T A When the value of the Cr is within this range, the thermal stability of the electrochemical system of the electrochemical device can be improved, the hot box performance can be further improved, and the high-temperature storage characteristics of the lithium ion battery can be obviously improved.

[0034] In some embodiments, T A is 110, 115, 120, 125, 130, 135, 136, or 136.5, or is in a range consisting of any two of these values. A When the temperature is within this range, the safety of the electrochemical device can be significantly improved.

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

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

[0037] In some embodiments, the tab protection layer further comprises a second polymer layer, and the second polymer layer has a melting point T B °C is T B ≦160, and T A and T B is 0 <T B -T A ≦60. T B -T A When the temperature is within this range, the electrochemical device has better safety.

[0038] In some embodiments, T B is 138, 140, 145, 150, 155, or 160, or is within a range consisting of any two of these values.

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

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

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

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

[0043] In some embodiments, the second polymer layer comprises at least one of Samsung CF330, TPC FS5611, and Exxon Mobil 6102FL.

[0044] In some embodiments, the tab protection layer is a single layer, a two layer, or a three layer structure.

[0045] In some embodiments, the tab protection layer comprises one first polymer layer, in some embodiments, one first polymer layer and one second polymer layer, or in some embodiments, the tab protection layer comprises two first polymer layers and one second polymer layer positioned between the two first polymer layers.

[0046] In some embodiments, the electrolyte further comprises a propionic acid ester, and 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%, or any range consisting of any two of these values, based on the weight of the electrolyte.

[0047] In some embodiments, the propionate 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 replaced with a fluorine atom.

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

[0049] In some embodiments, the trimethyl acetate compound has the structural formula: [ka] and Here, R is C1 to C 10 Alkyl, C2-C 10 Alkenyl, C1-C 10 Haloalkyl, C2-C 10 It is haloalkenyl, halogen, aryl, or amido.

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

[0051] In some embodiments, the trimethyl acetate compound comprises at least one of methyl trimethyl acetate and ethyl trimethyl acetate.

[0052] In some embodiments, the electrolyte further comprises at least one of a dinitrile compound and a trinitrile compound; wherein the dinitrile compound is further comprising at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 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 trinitrile compound is Further comprising at least one of 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tri(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, and 1,2,5-tris(cyanoethoxy)pentane.

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

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

[0055] In some embodiments, the electrolyte solution includes a trinitrile compound and ethylene glycol bis(propionitrile) ether, and the weight fraction of the trinitrile compound is a%, the content of the ethylene glycol bis(propionitrile) ether is b%, and 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 a range consisting 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 a range consisting of any two of these values.

[0057] In some embodiments, the electrolyte further comprises fluoroethylene carbonate and 1,3-propane sultone, wherein, based on the weight of the electrolyte, the weight fraction of the fluoroethylene carbonate is c%, the weight fraction of the 1,3-propane sultone is d%, and 6.0≦c+d≦15.0. In some embodiments, c+d is 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 range consisting of 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 a range consisting of any two of these values.

[0059] In some embodiments, the electrolyte may further include allyl nitrile.

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

[0061] In some embodiments, the electrodes include a negative electrode having a negative electrode active material capable of absorbing and desorbing metal ions, and a positive electrode having a positive electrode active material capable of absorbing and desorbing metal ions.

[0062] In some embodiments, the electrochemical device further comprises a separator positioned between the positive electrode and the negative electrode.

[0063] In some embodiments, the electrochemical device 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, an all-solid-state lithium secondary battery.

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

[0066] 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 is composed 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 is composed of a first polymer layer 2-5 and a second polymer layer 2-4.

[0067] 3 shows the structure of a tab protection layer in another embodiment of the present invention. The 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 main role of the tab protection layer is to adhere to the tab of the lithium-ion battery so that the tab can be heat-sealed to the polypropylene layer inside the polymer battery packaging bag. While currently used tab protection layers generally have a melting point of 140°C or higher, the present invention primarily uses a tab protection layer with a lower melting point to allow the battery to dissipate heat quickly and further improve the thermal safety of the battery.

[0069] negative electrode The materials, construction, and manufacturing method of the negative electrode used in the electrochemical device of the present invention may include any of the techniques disclosed in the prior art. In some embodiments, the negative electrode is the negative electrode described in U.S. Patent Application No. US9812739B, the entire contents of which are incorporated herein by reference.

[0070] In some embodiments, the negative electrode includes a current collector and a negative electrode active material layer disposed 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 includes lithium metal, structured lithium metal, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, silicon oxide materials, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and lithiated TiO2-Li4Ti5O with a spinel structure. 12 , Li-Al alloys, or any combination thereof.

[0071] In some embodiments, the negative electrode active material layer includes a binder, including, but not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, or nylon.

[0072] In some embodiments, the negative electrode active material layer includes a conductive material, including, but not limited to, natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, or a polyphenylene derivative.

[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 on a current collector.

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

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

[0077] positive electrode The positive electrode materials used in the electrochemical devices of the present invention can be prepared using materials, structures, and manufacturing methods known in the art. In some embodiments, the positive electrodes of the present invention can be prepared using the techniques described in U.S. Patent Application No. US9812739B, the entire contents of which are incorporated herein by reference.

[0078] In some embodiments, the positive electrode includes a current collector and a positive electrode active material layer disposed on the current collector. The positive electrode active material includes at least one lithiated intercalation compound that reversibly absorbs and releases lithium ions. In some embodiments, the positive electrode active material includes a composite oxide. In some embodiments, the composite oxide contains 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 (LiCoO), lithium nickel cobalt manganese (NCM) ternary materials, lithium ferrous phosphate (LiFePO), lithium manganese oxide (LiMnO), 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 include at least one coating element compound selected from oxides of the coating element, hydroxides of the coating element, hydroxy oxides of the coating element, carbonate oxygen salts of the coating element, and hydroxy carbonate salts of the coating element. The compound used for the coating may be amorphous or crystalline.

[0081] In some embodiments, the coating elements included in the coating can 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 that does not adversely affect the performance of the positive electrode active material. For example, the method can include any application method known in the art, such as spraying, dipping, etc.

[0082] The positive electrode active material layer further contains a binder and, optionally, 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, binders include, but are not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resins, nylon, and the like.

[0084] In some embodiments, the conductive material includes, but is not limited to, a carbon-based material, a metal-based material, a conductive polymer, and a mixture thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, and 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 is a polyphenylene derivative.

[0085] In some embodiments, the current collector can be, but is not limited to, aluminum.

[0086] The positive electrode can be prepared by a preparation method known in the art. For example, the positive electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and then coating the active material composition on a current collector. In some embodiments, the solvent can 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 including a lithium transition metal compound powder and a binder.

[0088] In some embodiments, the positive electrode active material layer can be typically produced by dry-mixing the positive electrode material and a binder (including an optional conductive material and thickener) to form a sheet, and then pressing the resulting sheet onto a positive electrode current collector, or by dissolving or dispersing these materials in a liquid medium to form a slurry, which is then applied to a positive electrode current collector and dried. In some embodiments, the material for the positive electrode active material layer includes any material known in the art.

[0089] Separator In some embodiments, the electrochemical device of the present invention includes a separator between the positive electrode and the negative electrode to prevent short circuits. The material and shape of the separator used in the electrochemical device 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, the separator may include a substrate layer and a surface treatment layer. The substrate layer may be a porous nonwoven fabric, a membrane, or a composite membrane, and the material of the substrate layer may be 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 may 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 may be a layer formed by mixing a polymer and an inorganic layer.

[0092] The inorganic layer includes inorganic particles and a binder, the inorganic particles being selected from one or more 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, and the binder being selected from one or more of a polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate salt, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The polymer layer includes a polymer, and the polymer material includes at least one of polyamide, polyacrylonitrile, polymer of acrylic ester, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0093] electrolyte The electrolyte used in the electrolytic solution of the present invention may be any electrolyte known in the art, such as inorganic lithium salts such as LiClO, LiAsF, LiPF, LiBF, LiSbF, LiSO, LiN(FSO), LiCF, LiN(FSO), LiN(FSO), LiN(CF, FSO), LiN(CF, FSO), cyclic 1,3-hexafluoropropanebissulfonylimide lithium, cyclic 1,2-tetrafluoroethanebissulfonylimide lithium, LiN(CF, SO), LiC(CF, SO), LiPF, LiPF, LiPF, LiF ... Examples of suitable electrolytes include, but are not limited to, fluorine-containing organic lithium salts such as iPF(CFSO), LiPF(CFSO), LiBF(CF), LiBF(CFSO), LiBF(CFSO), and LiBF(CFSO); and dicarboxylic acid complex-containing lithium salts such as lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate. These electrolytes may be used singly or in combination. For example, in some embodiments, the electrolyte may include a combination of LiPF and LiBF. In some embodiments, the electrolyte may include a combination of an inorganic lithium salt such as LiPF or LiBF with a fluorine-containing organic lithium salt such as LiCFSO, LiN(CFSO), or LiN(CFSO). In some embodiments, the concentration of the electrolyte is in the range of 0.8-3 mol / L, e.g., in the range of 0.8-2.5 mol / L, in the range of 0.8-2 mol / L, in the range of 1-2 mol / L, 0.5-1.5 mol / L, 0.8-1.3 mol / L, 0.5-1.2 mol / L, e.g., 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 an electrochemical device according to an embodiment of the present invention.

[0095] In some embodiments, the electronic device includes, but is not limited to, a laptop computer, a pen-based computer, a mobile computer, an electronic book player, a mobile phone, a portable facsimile machine, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD television, a portable vacuum cleaner, a portable CD player, a minidisc, a walkie-talkie, an electronic organizer, a calculator, a memory card, a portable tape recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, an electric bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery, and a lithium ion capacitor.

[0096] Hereinafter, a lithium ion battery will be taken as an example, and the preparation of the lithium ion battery will be described with reference to specific examples. Those skilled in the art should understand that the preparation method described in the present invention is merely exemplary, and any other suitable preparation method is also within the scope of the present invention.

[0097] <Example> Below, performance evaluation will be carried out based on examples and comparative examples of the lithium ion battery of the present invention.

[0098] [1. Preparation of Lithium-ion Battery] (1) Preparation of electrolyte In an argon atmosphere glove box with a water content of <10 ppm, ethylene carbonate (EC), propylene carbonate (PC), and other organic solvents, including at least one selected from diethyl carbonate (DEC), ethyl propionate (EP), and propyl propionate (PP), were mixed in a certain ratio. LiPF was then added and stirred uniformly to form a base electrolyte solution, where the LiPF concentration was 1.15 mol / L. The electrolyte solutions of different examples and comparative examples were obtained by adding different amounts of the substances shown in the following tables to the base electrolyte solution. The content of each substance in the electrolyte solutions described in this invention was calculated based on the weight of the electrolyte solution. The contents of EC and PC in Table 1 are shown in the table, and the remaining organic solvent is DEC.

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

[0100] (3) Preparation of the negative electrode Graphite, the negative electrode active material, styrene butadiene rubber (SBR), the binder, and sodium carboxymethyl cellulose (CMC), the thickener, were mixed in a weight ratio of 95:2:3 in an appropriate amount of deionized water solvent with sufficient stirring to form a uniform negative electrode slurry. This slurry was then applied to Cu foil, the negative electrode current collector, dried, and cold-pressed to obtain the negative electrode.

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

[0102] (5) Preparation of Lithium-ion Battery The tab protective layer and metal tape were combined using flat plate heating or high-frequency heating to form a tab containing the tab protective layer, which was then welded to the positive and negative electrodes. The positive electrode, separator, and negative electrode were then stacked in this order, with the separator positioned between the positive and negative electrodes to isolate them. The resulting stack was then wound and placed in an outer foil. The dried battery was then filled with the prepared electrolyte, and the resulting lithium-ion battery was then completed through processes such as vacuum packaging, standing, formation, and shaping.

[0103] [2.Measurement method] 1, Hot box test: At 25°C, the lithium-ion batteries were charged at a constant current of 0.7C up to 4.45V, and then further charged at 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 rate of 5±2°C / min. The battery was maintained at this temperature for 1 hour, and the changes in the battery voltage, temperature, and hot box temperature were recorded. The test was considered passed if no fire or explosion occurred. Ten batteries per set were tested, and the number of batteries that passed the test was recorded.

[0104] 2. High temperature storage test: The lithium-ion battery was left at 25°C for 30 minutes. It was then charged at a constant current of 0.5C to 4.45V, and then charged at a constant voltage of 0.05C at 4.45V. It was then left at rest for 5 minutes. The thickness of the lithium-ion battery was measured and recorded as h0. The lithium-ion battery was then placed in a thermostatic box at 85°C and stored for 24 days. 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, the lithium-ion battery was charged at a constant current of 0.7C to 4.45V, and then charged at a constant voltage of 4.45V until the current reached 0.05C. The lithium-ion battery was then left at different temperatures (25°C, 0°C, -10°C) for 4 hours, after which it was discharged at 0.2C to 3.0V. After each discharge, the battery was left to stand for an additional 5 minutes, and the discharge capacity of the lithium-ion battery was recorded. The discharge capacity ratio of the lithium-ion battery at different temperatures was calculated based on the discharge capacity at 25°C. Lithium-ion battery discharge capacity ratio (%) at different temperatures = discharge capacity at different temperatures (0°C, -10°C) / discharge capacity at 25°C × 100%

[0106] 4. High temperature storage test The lithium-ion battery was left standing at 25°C for 30 minutes, then charged at a constant current of 0.5C up to 4.45V, then charged at a constant voltage of 0.05C at 4.45V, left standing for 5 minutes, and then stored at 85°C for 24 days. 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] Table 1 shows the composition and performance test results of the lithium ion batteries in the relevant examples. Here, the tab protection layer used in Comparative Examples D1-1 and D1-2 consists of one second polymer layer, the melting point of which is T B The second polymer layer is selected from Samsung's CF330 block copolymer polypropylene. The tab protection layers used in Comparative Examples D1-3 to D1-5 and Examples S1-1 to S1-7 consist of one first polymer layer, the melting point of which is T A The first polymer layer is Bynel 50E632 (melting point 136.5 o C), Bynel 50E631 (melting point 136 o C), Bynel 40E529 (melting point 135 o C), Bynel 50E662 (melting point 130 o C), Bynel 4104 (melting point 125 oC), Bynel 4208 (melting point 110 o C), Nucrel 0910 (melting point 100 o C) is selected.

[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 only passed the hot box test at 130°C, and the pass rates for the hot box tests at 132°C and 135°C were both low. This is because the melting points of the tab protective layers of Comparative Examples D1-1 and D1-2 are relatively high. During abuse tests such as hot box tests, the gas does not open the gas bag in a timely manner, and the generated heat gradually accumulates inside the battery, making it very likely to cause battery ignition, combustion, and even explosion. Adjusting the total amount of EC+PC or adjusting the melting point of the polymer layer has a significant effect on hot box performance, but when the EC+PC content is low, adjusting the melting point does not have any significant effect. On the other hand, when the EC+PC content is high, adjusting the melting point has an effect on hot box performance, but the electrical performance is relatively poor. Therefore, both of these 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, when the tab protection layer prepared from the second polymer layer is replaced with the tab protection layer prepared from the first polymer layer, and the melting point value T of the first polymer layer is A and the EC+PC content value Y are 0.147 <Y / T AWhen the ratio <0.7 is satisfied, the pass rate of the hot box test of the lithium-ion battery is significantly improved. On the one hand, the introduction of the first polymer layer into the tab protective layer allows the gas inside the battery to open the gas bag earlier and release heat in a timely manner, which significantly improves the hot box test. On the other hand, it improves the thermal stability of the entire electrochemical system, which further improves the hot box performance and significantly improves the high-temperature storage characteristics of the lithium-ion battery.

[0111] Tables B, 2, and 3 show the compositions and performance test results of lithium-ion batteries in related examples. Here, the tab protection layer in Examples S2-1 to S2-3 has a two-layer structure, including one first polymer layer and one second polymer layer. The tab protection layer in Example S3-1 has a three-layer structure, i.e., two first polymer layers and one second polymer layer between them, and the melting point value T of the first polymer layer is 0. A The temperatures were both 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, replacing the tab protection layer prepared from the second polymer layer in Comparative Example D1-2 with the above-mentioned two-layer and three-layer tab protection layers can similarly improve the performance of lithium-ion batteries in hot box tests. This is because, whether the two-layer or three-layer structure contains a low-melting point layer, it can release heat from the battery in a timely manner even at low temperatures, preventing thermal runaway of the battery.

[0115] C, Table 4 shows the composition and performance test results of the lithium ion batteries in the relevant examples. The preparation of the lithium ion batteries in Examples S4-1 and S4-2 is the same as that in Example S1-2, except that the composition of the electrolyte is different, as shown in Table 4.

[0116] [Table 4]

[0117] As can be seen from the test results in Table 4, the melting point T A and the EC+PC content Y are 0.147 <Y / T A When <0.7 is satisfied, 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 and ethyl propionate to the electrolyte.

[0118] D, Table 5 shows the composition and performance test results of the lithium ion batteries in the related examples. The preparation process of the lithium ion batteries in Examples S5-1 to S5-3 is the same as that in Example S1-2, except that the composition of the electrolyte is different, and the details are shown in Table 5.

[0119] [Table 5] As can be seen from the test results in Table 5, the melting point T A and the EC+PC content Y are 0.147 <Y / T A When <0.7 is satisfied, adding a certain amount of trimethyl acetate to the electrolyte can further improve the hot box performance of lithium-ion batteries.

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

[0121] [Table 6] As can be seen from the test results in Table 6, the melting point T A and the EC+PC content Y are 0.147 <Y / T A When <0.7 is satisfied, adding a certain amount of dinitrile compounds and trinitrile compounds to the electrolyte can further improve the hot box performance of lithium-ion batteries.

[0122] F, Table 7 shows the composition and performance test results of the lithium ion batteries in the related examples. The preparation process of the lithium ion batteries in Examples S7-1 to S7-11 is the same as that in Example S1-2, except that the composition of the electrolyte is different, and the details are shown in Table 7.

[0123] [Table 7]

[0124] As can be seen from the test results in Table 7, the melting point T A and the EC+PC content Y are 0.147 <Y / T A When the ratio is <0.7, adding a certain amount of fluoroethylene carbonate to the electrolyte reduces the hot box performance of the battery to a certain extent, and adding 1,3-propane sultone does not significantly affect the hot box performance. However, when both compounds are present simultaneously, the hot box performance of the lithium-ion battery can be further improved, which is presumably related to the film formation caused by their combined use. When both compounds are present simultaneously, the optimal effect can be achieved by adding both a dinitrile compound and a trinitrile compound simultaneously.

[0125] Throughout the specification, references to "some embodiments," "some of the embodiments," "one embodiment," "another example," "an example," "a specific example," or "some of the examples" mean that at least one embodiment or example of the present invention includes the particular feature, structure, material, or characteristic described in that embodiment or example. Thus, the appearances of, for example, "some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," "in a particular example," or "example" throughout the specification do not necessarily refer to the same embodiment or example of the present invention. Furthermore, particular features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

[0126] Although exemplary embodiments have been described and illustrated, those skilled in the art should understand that the above-described embodiments are not to be construed as limiting the present invention, and that modifications, substitutions, and alterations to the embodiments are possible without departing from the spirit, principle, and scope of the present invention.

Claims

1. An electrochemical device 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 protection layer located on the tab; the tab protection layer comprises a first polymer layer; The melting point T of the first polymer layer Ａ ° C., 110≦T Ａ ≦136.5, the electrolyte solution contains ethylene carbonate and propylene carbonate; When the sum of the weight fraction of the ethylene carbonate and the weight fraction of the propylene carbonate is Y % based on the weight of the electrolytic solution, Y is 20 to 80, and Y and T Ａ is 0.147<Y / T Ａ <0.7, The electrolyte solution further contains a dinitrile compound and a trinitrile compound, the dinitrile compound includes at least one of succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, 1,7-dicyanoheptane, 1,8-dicyanoctane, 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 trinitrile compound includes at least one of 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tri(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, and 1,2,5-tris(cyanoethoxy)pentane.

2. the tab protection layer further comprises a second polymer layer; The melting point T of the second polymer layer Ｂ °C is T Ｂ ≦160, and T Ａ and T Ｂ is 0<T Ｂ -T Ａ 50. The electrochemical device of claim 1 .

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

4. The electrochemical device of claim 2 , wherein the second polymer layer comprises a polypropylene resin.

5. The electrolyte solution further comprises a propionic acid ester; 2. The electrochemical device of claim 1, wherein the weight fraction of the propionate ester is 10% to 60% based on the weight of the electrolyte.

6. the propionate 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; 6. The electrochemical device of claim 5, wherein fluoro means that at least one hydrogen atom is replaced with a fluorine atom.

7. 10. The electrochemical device of claim 1, wherein the electrolyte further comprises a trimethyl acetate compound.

8. The structural formula of the trimethyl acetate compound is: 【Chemistry 1】 and where R is C １ ~C １０ Alkyl, C ２ ~C １０ Alkenyl, C １ ~C １０ Haloalkyl, C ２ ~C １０ 8. The electrochemical device of claim 7, wherein the group is haloalkenyl, halogen, aryl, or amide.

9. 8. The electrochemical device of claim 7, wherein the trimethyl acetate compound comprises at least one of methyl trimethyl acetate and ethyl trimethyl acetate.

10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.

Images