Electrochemical device and electronic device

Abstract

The application relates to an electrochemical device and an electronic device, the electrochemical device comprising a positive electrode sheet, a negative electrode sheet and a separator film arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, the positive electrode current collector containing silicon elements, the mass content of the silicon elements being a% based on the mass of the positive electrode current collector; the electrochemical device further comprising an electrolyte, the electrolyte comprising a fluorinated solvent and an imine compound, the mass content of the fluorinated solvent being b% and the mass content of the imine compound being c% based on the mass of the electrolyte, the electrochemical device satisfying 0 < a / c < 1 and 0 < b / c < 80. The cycle performance and high-temperature storage performance of the electrochemical device are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, and more particularly, to an electrochemical device and an electronic device. BACKGROUND

[0002] The electrochemical device has the characteristics of high energy density, high working voltage, and light weight, and is widely used in electronic products such as mobile phones, notebook computers, and cameras. While improving the electrochemical performance of the electrochemical device, its safety performance cannot be ignored. With the increasing demand for the performance of electronic products, the performance requirements for the electrochemical device are also gradually increasing.

[0003] Research has found that the electrochemical device includes a positive electrode sheet containing a positive electrode current collector and an electrolyte. The exposed positive electrode current collector can react with the electrolyte, and the products generated by the side reaction can adhere to the positive electrode current collector, which can deteriorate the cycle performance and high-temperature storage performance of the electrochemical device. SUMMARY

[0004] The present application provides an electrochemical device and an electronic device, and the cycle performance and high-temperature storage performance of the electrochemical device are significantly improved.

[0005] In a first aspect, the present application provides an electrochemical device, the electrochemical device comprising a positive electrode sheet, a negative electrode sheet, and a separator film arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, the positive electrode current collector containing silicon, and the mass content of silicon is a% based on the mass of the positive electrode current collector; the electrochemical device further comprises an electrolyte, the electrolyte comprising a fluorinated solvent and an amine compound, the mass content of the fluorinated solvent is b% based on the mass of the electrolyte, and the mass content of the amine compound is c%, the electrochemical device satisfies: 0

[0006] According to any one of the embodiments of the first aspect of the present application, the electrochemical device further satisfies: 0.3≤a / c≤0.7, and / or 15≤b / c≤65.

[0007] According to any one of the embodiments of the first aspect of the present application, the electrochemical device further satisfies: 0

[0008] According to any one of the embodiments of the first aspect of the present application, the electrochemical device satisfies at least one of conditions (1) to (3): (1) 0.03≤a≤0.18; optionally, 0.06≤a≤0.15; (2) 0.10≤b≤50; optionally, 3≤b≤30; (3) 0.1≤c≤5.0; optionally, 0.8≤c≤4.0.

[0009] According to any one of the embodiments of the first aspect of the present application, the fluorous solvent includes a fluorous carbonate and / or a fluorous carboxylate; optionally, the fluorous carbonate includes one or more of fluorous ethylene carbonate, fluorous propylene carbonate, fluorous diethyl carbonate, fluorous diethylene carbonate, bis(trifluoromethyl) carbonate, bis(pentafluoroethyl) carbonate, and bis(2,2,2-trifluoroethyl) carbonate; the fluorous carboxylate includes one or more of fluorous methyl formate, fluorous ethyl formate, fluorous ethyl acetate, and fluorous propyl acetate.

[0010] According to any one of the embodiments of the first aspect of the present application, the amine compound includes an organic amine compound and a salt thereof.

[0011] The organic amine compound and the salt thereof include a compound represented by Formula (I) and a salt thereof:

[0012]

[0013] In Formula (I), R1and R2are each independently selected from a substituted or unsubstituted C1-C10 linear or cyclic alkyl group, a substituted or unsubstituted C2-C10 linear or cyclic alkenyl group, a substituted or unsubstituted C2-C10 linear or cyclic alkynyl group, a substituted or unsubstituted C1-C10 acyl group, a sulfonyl group; when substituted, the substituent is a halogen atom; and / or

[0014] The organic amine compound and the salt thereof include a compound represented by Formula (II):

[0015]

[0016] In Formula (II), R3and R4are each independently selected from a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group, when substituted, the substituent is a halogen atom; optionally, R3and R4are each independently selected from a substituted or unsubstituted C1 to C 20 alkyl group, or a substituted or unsubstituted C1 to C 20 cycloalkyl group; M is selected from an alkali metal atom; optionally, M is selected from a sodium atom, a lithium atom, or a potassium atom.

[0017] According to any one of the embodiments of the first aspect of the present application, the organic amine compound and salt thereof include one or more of bistrifluoromethanesulfonimide, trifluoromethanesulfonamide, N,N-bis(pentafluoroethane sulfonimide), dimethanesulfonamide, bistrifluoroacetamide, 2,2,2-trifluoro-N-(2,2,2-trifluoroethyl)acetamide, 2,2,2-trifluoro-N-isopropylacetamide, magnesium bistrifluoromethanesulfonimide, and 2-(trifluoroacetamido)ethylamine hydrochloride; and / or the organic amine compound and salt thereof include one or more of lithium bisfluorosulfonimide (LiN(SO2F)2), lithium bistrifluoromethanesulfonimide (LiN(SO2CF3)2), and lithium bisfluorophosphonimide (LiN(POF2)2).

[0018] According to any one of the embodiments of the first aspect of the present application, the electrolyte contains a fluorine-containing lithium salt, and the fluorine-containing lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium bistrifluoromethanesulfonimide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0019] According to any one of the embodiments of the first aspect of the present application, the molar concentration of the fluorine-containing lithium salt is denoted as N mol, and 0.8≤N≤1.4; optionally, 1.0≤N≤1.3.

[0020] According to any one of the embodiments of the first aspect of the present application, the positive electrode active material layer is disposed on one surface of the negative electrode current collector.

[0021] According to any one of the embodiments of the first aspect of the present application, the positive electrode active material layer is disposed on two surfaces of the positive electrode current collector opposite to each other along the thickness direction of the positive electrode current collector, and the positive electrode active material layer covers part of the two surfaces.

[0022] According to any one of the embodiments of the first aspect of the present application, the two surfaces include a first surface and a second surface, the positive electrode active material layer is disposed on the first surface, and the positive electrode active material layer is disposed on part of the second surface; the area of the second surface not covered by the positive electrode active material layer is denoted as S1, with the unit of μm 2 ; the area of the second surface covered by the positive electrode active material layer is denoted as S2, with the unit of μm 2 ; and the electrochemical device satisfies: S1 / S2≥0.03; optionally, 0.05≤S1 / S2≤0.1.

[0023] In a second aspect, the present application provides an electronic device including the electrochemical device according to any one of the embodiments of the first aspect of the present application.

[0024] According to the electrochemical device provided in the embodiments of the present application, when the silicon element and the fluorinated solvent react to generate a silicon-containing product, the amine compound is introduced into the electrolyte, and the amine compound can dissolve the silicon-containing product, thereby reducing the risk of local enrichment of the silicon-containing product on the positive current collector, improving the interface performance of the overall positive electrode sheet, and improving the cycle performance and high-temperature storage performance of the electrochemical device. In particular, when 0 < a / c < 1 and 0 < b / c < 80, the amine compound can basically dissolve the silicon-containing product attached to the positive current collector in the electrolyte, further reducing the risk of local enrichment of the silicon-containing product on the positive current collector, and further improving the cycle performance and high-temperature storage performance of the electrochemical device. BRIEF DESCRIPTION OF DRAWINGS

[0025] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0026] Figure 1 is a structural schematic diagram of a positive electrode sheet of an electrochemical device provided in an embodiment of the present application;

[0027] Figure 2 is a structural schematic diagram of a positive electrode sheet of an electrochemical device provided in another embodiment of the present application;

[0028] The accompanying drawings are not necessarily drawn to scale.

[0029] Reference Signs List:

[0030] 10, positive current collector; 20, positive active material layer. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below. In the entire specification of the present application, the same or similar components and components having the same or similar functions are denoted by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative, diagrammatic, and for providing a basic understanding of the present application. The embodiments of the present application should not be interpreted as limiting the present application.

[0032] In addition, sometimes the amounts, ratios, and other numerical values are presented in a range format in the specification. It is to be understood that such range format is used merely for the convenience and brevity of the specification and that the upper value and the lower value of a range can be combined with any other upper value or lower value to generate further ranges not explicitly listed. All of the individual values of the range are included in the embodiments of the present application.

[0033] In the DETAILED DESCRIPTION and in the claims, a list of items joined by the term "one or more of" can mean any combination of those listed items. For example, if A and B are listed, the phrase "at least one of A and B" means A alone, B alone, or both A and B. In another example, if A, B, and C are listed, the phrase "at least one of A, B, and C" means A alone, B alone, C alone, A and B (not C), A and C (not B), B and C (not A), or all of A, B, and C. Item A can include a single element or multiple elements. Item B can include a single element or multiple elements. Item C can include a single element or multiple elements.

[0034] The term "cyclic alkyl" refers to carbon atoms greater than or equal to three that form a ring structure. For example, a cyclic alkyl can be C3 to C 50 alkyl, C1 to C 40 alkyl, C1 to C 30 alkyl, C1 to C 20 alkyl, C1 to C 12 alkyl, C1 to C 10 alkyl, C1 to C6 alkyl, C1 to C4 alkyl. In some embodiments, a cyclic alkyl includes cyclopropyl, cycloisopropyl, cyclobutyl, cycloisobutyl, cyclo-tert-butyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like. Additionally, a cyclic alkyl can be optionally substituted.

[0035] The term "cyclic alkyl" refers to carbon atoms greater than or equal to three that form a ring structure. For example, a cyclic alkyl can be C3 to C 50 cycloalkyl, C3 to C 40 cycloalkyl, C3 to C 30 cycloalkyl, C3 to C 20 cycloalkyl, C3 to C 12 cycloalkyl, C3 to C 10 cycloalkyl, C3 to C6 cycloalkyl, C3 to C4 cycloalkyl. In some embodiments, a cyclic alkyl includes cyclopropyl, cycloisopropyl, cyclobutyl, cycloisobutyl, cyclo-tert-butyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like. Additionally, a cyclic alkyl can be optionally substituted.

[0036] The term "cyclic alkyl" refers to carbon atoms greater than or equal to three that form a ring structure. For example, a cyclic alkyl can be C3 to C 50 alkenyl, C2 to C 40 alkenyl, C2 to C 30 alkenyl, C2 to C 20 alkenyl, C2 to C 12 alkenyl, C2 to C 10 alkenyl, C2 to C6 alkenyl, C2 to C4 alkenyl. In some embodiments, a cyclic alkenyl includes cyclopropenyl, cycloisopropenyl, cyclobutenyl, cycloisobutenyl, cyclo-tert-butenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, and the like. Additionally, a cyclic alkenyl can be optionally substituted.Alkenyl, C2 to C6 alkenyl, C2 to C6 alkenyl, C2 to C4 alkenyl. In some embodiments, a catenary alkenyl includes ethenyl, propenyl, butenyl, isobutenyl, pentenyl, hexenyl, heptenyl, octenyl, and the like. Additionally, a catenary alkenyl can be optionally substituted.

[0037] The term "cyclic alkenyl" refers to greater than or equal to three carbon atoms that form a ring structure with double bonds. For example, a cyclic alkenyl can be C3 to C 50 Cycloalkenyl, C3 to C 40 Cycloalkenyl, C3 to C 30 Cycloalkenyl, C3 to C 20 Cycloalkenyl, C3 to C 12 Cycloalkenyl, C3 to C 10 Cycloalkenyl, C3 to C6 cycloalkenyl, C3 to C6 cycloalkenyl, C3 to C4 cycloalkenyl. In some embodiments, a cyclic alkenyl includes cycloethenyl, cyclopropenyl, cyclobutenyl, cycloisobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, and the like. Additionally, a cyclic alkenyl can be optionally substituted.

[0038] The term "catenary alkynyl" encompasses straight-chain and branched-chain alkynyl groups. For example, an alkynyl can be C2 to C 50 Alkynyl, C2 to C 40 Alkynyl, C2 to C 30 Alkynyl, C2 to C 20 Alkynyl, C2 to C 12 Alkynyl, C2 to C 10 Alkynyl, C2 to C6 alkynyl, C2 to C6 alkynyl, C2 to C4 alkynyl. In some embodiments, a catenary alkynyl includes ethynyl, propynyl, butynyl, isobutynyl, pentynyl, hexynyl, heptynyl, octynyl, and the like. Additionally, an alkynyl can be optionally substituted.

[0039] The term "cyclic alkynyl" refers to greater than or equal to three carbon atoms that form a ring structure with triple bonds. For example, a cyclic alkynyl can be C3 to C 50 Cycloalkynyl, C3 to C 40 Cycloalkynyl, C3 to C 30 Cycloalkynyl, C3 to C 20 Cycloalkynyl, C3 to C 12 Cycloalkynyl, C3 to C 10 Cycloalkynyl, C3 to C6 cycloalkynyl, C3 to C6 cycloalkynyl, C3 to C4 cycloalkynyl. In some embodiments, a cyclic alkynyl includes cycloethynyl, cyclopropynyl, cyclobutyryl, cycloisobutyryl, cyclopentyryl, cyclohexyryl, cycloheptyryl, cyclooctyryl, and the like. Additionally, a cyclic alkynyl can be optionally substituted.

[0040] The term "acyl" refers to the atomic group remaining after removing one or more hydroxyl groups from an organic or inorganic oxyacid. For example, an acyl group can be C1 to C2. 50 Acyl group, C1 to C 40 Acyl group, C1 to C 30 Acyl group, C1 to C 20 Acyl group, C1 to C 12 Acyl group, C1 to C 10 Acyl group, C1 to C8 acyl group, C1 to C5 acyl group, C2 to C6 acyl group. In some embodiments, the acyl group may include formyl group, acetyl group, propionyl group, butyryl group, isobutyryl group, sec-butyryl group, tert-butyryl group, cyclobutyryl group, valeryl group, isovaleryl group, neovaleryl group, tert-valeryl group, cyclovaleryl group. Additionally, the acyl group may optionally be substituted.

[0041] The term "sulfonyl group" refers to the atomic group remaining after removing one or more hydroxyl groups from a sulfonic acid. For example, the sulfonyl group can be C1 to C2. 50 sulfonyl, C1 to C 40 sulfonyl, C1 to C 30 sulfonyl, C1 to C 20 sulfonyl, C1 to C 12 sulfonyl, C1 to C 10 The sulfonyl group comprises C1 to C8 sulfonyl, C1 to C5 sulfonyl, and C2 to C6 sulfonyl groups. In some embodiments, the sulfonyl group may include methanesulfonyl, ethanesulfonyl, propanesulfonyl, butanesulfonyl, isobutanesulfonyl, sec-butanesulfonyl, tert-butanesulfonyl, cyclobutanesulfonyl, pentasulfonyl, isopentanesulfonyl, neopentanesulfonyl, tert-pentanesulfonyl, and cyclopentanesulfonyl. Additionally, the sulfonyl group may optionally be substituted.

[0042] The term "halogen atom" refers to fluorine atoms, chlorine atoms, bromine atoms, etc.

[0043] Throughout this specification, substituents of compounds are disclosed by groups or ranges. It is expressly intended that such description include each individual sub-combination of members of these groups and ranges. For example, it is expressly intended that the term "C1 to C8 alkyl" individually discloses C1, C2, C3, C4, C5, C6, C7, C8, C1 to C8, C1 to C7, C1 to C6, C1 to C5, C1 to C4, C1 to C3, C1 to C2, C2 to C8, C2 to C7, C2 to C6, C2 to C5, C2 to C4, C2 to C3, C3 to C8, C3 to C7, C3 to C6, C3 to C5, C3 to C4, C4 to C8, C4 to C7, C4 to C6, C4 to C5, C5 to C8, C5 to C7, C5 to C6, C6 to C8, C6 to C7, and C7 to C8 alkyl.

[0044] As other examples, it is expressly contemplated that integers within a range of 5 to 40 are disclosed individually as 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40; and it is expressly contemplated that integers within a range of 1 to 20 are disclosed individually as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Other groups or ranges are expressly contemplated in like manner.

[0045] When the above group is substituted, the substituent group can include a halogen atom.

[0046] The electrochemical device includes a positive electrode tab including a positive electrode active material layer and a positive electrode current collector (e.g., an aluminum foil), and the aluminum foil can have a partial bare area, which refers to an area not covered by the positive electrode active material layer, when assembled as a component of the positive electrode tab. Exemplarily, when the electrochemical device adopts a winding structure, the positive electrode tab has a bare aluminum foil at the end of the positive electrode tab and a bare aluminum foil at the end of the single-sided area of the positive electrode tab.

[0047] Since the fluorinated solvent can form an interface film on the surface of the negative electrode tab of the electrochemical device, it plays a good protective role on the negative electrode tab; and the fluorinated solvent can improve the thermal stability of the electrolyte, so in the related art, the fluorinated solvent is usually added to the electrolyte. With the increasing requirement for the performance of the electrochemical device, the voltage system is continuously improved, so the addition of the fluorinated solvent is continuously increased; and with the increase of the content of the fluorinated solvent, the risk of side reaction with silicon elements increases.

[0048] The inventors found that the aluminum foil inevitably carries silicon elements during the production process, and the silicon elements are prone to side reaction with the fluorinated solvent in the electrolyte. The products generated by the side reaction can be attached to the positive electrode current collector, affecting the deintercalation of active ions in the positive electrode tab, causing local precipitation of active ions in the positive electrode tab, and thus deteriorating the cycle performance and high-temperature storage performance of the electrochemical device, and in severe cases, the electrochemical device may be cycled to failure.

[0049] In view of this, the inventors of the present application propose an electrochemical device, which adjusts the components of the electrolyte to reduce the risk of enrichment of the products generated by the reaction of silicon elements and the fluorinated solvent on the positive electrode current collector, thereby improving the cycle performance and high-temperature storage performance of the electrochemical device.

[0050] Next, the technical solutions of the present application will be described in detail.

[0051] Electrochemical device

[0052] The first aspect of the present application provides an electrochemical device, the electrochemical device comprising an electrolyte, a positive electrode sheet, a negative electrode sheet, and a separator film arranged between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer arranged on the surface of the positive electrode current collector, the positive electrode current collector containing silicon elements, the mass content of the silicon elements being a% based on the mass of the positive electrode current collector. The electrolyte comprises a fluorinated solvent and an amine compound; the mass content of the fluorinated solvent is b% and the mass content of the amine compound is c% based on the mass of the electrolyte, and the electrochemical device satisfies: 0

[0053] It should be noted that when the positive electrode active material layer is arranged on the positive electrode current collector, part of the surface of the positive electrode current collector may not be covered by the positive electrode active material layer, and this part of the positive electrode current collector has a bare surface. The silicon elements contained in this part of the positive electrode current collector can be in direct contact with the electrolyte. When the electrochemical device contains silicon elements and a fluorinated solvent, a side reaction occurs between the silicon elements and the fluorinated solvent to generate a silicon-containing product. The introduction of the amine compound into the electrolyte can dissolve the silicon-containing product, thereby reducing the risk of local enrichment of the silicon-containing product on the positive electrode current collector and improving the overall interface performance of the positive electrode sheet, thereby improving the cycle performance and high-temperature storage performance of the electrochemical device. Especially when the present application satisfies: 0

[0054] Illustratively, a / c can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or any value within the range of any two of the above values.

[0055] Illustratively, b / c can be 1, 2, 5, 8, 10, 15, 18, 20, 22, 25, 30, 35, 40, 45, 50, 60, 65, 70, 75, 80, or any value within the range of any two of the above values.

[0056] In some embodiments, the electrochemical device further satisfies: 0 < a x b / c < 10. When the content of the amine compound, the fluorinated solvent and the silicon element satisfies the above range, the amine compound can further dissolve the silicon-containing product in the electrolyte, and further improve the cycle performance and high-temperature storage performance of the electrochemical device. Optionally, 1 < a x b / c < 9, which can make the electrochemical device have better cycle performance and high-temperature storage performance. Exemplarily, a x b / c can be 0.2, 0.5, 1, 1.5, 1.8, 2.5, 3.0, 4.0, 4.5, 6.0, 7.0, 8.0, 9.0, 9.8 or any value within a range consisting of any two of the above values.

[0057] The inventors have further found that when the electrochemical device further satisfies at least one of the following conditions, the cycle performance and high-temperature storage performance of the electrochemical device can be further improved.

[0058] In some embodiments, 0.03 < a < 0.18. When the mass content of the silicon element is within the above range, the risk of side reactions between the silicon element and the electrolyte can be reduced. Optionally, 0.06 < a < 0.15, which can make the electrochemical device have better cycle performance and high-temperature storage performance. Exemplarily, the mass content a% of the silicon element can be 0.03%, 0.05%, 0.06%, 0.08%, 0.10%, 0.12%, 0.15%, 0.17%, 0.18% or any value within a range consisting of any two of the above values.

[0059] In some embodiments, 0.10 < b < 50. When the mass content of the fluorinated solvent is within the above range, the fluorinated solvent and the silicon element can have side reactions to a certain extent, but the extent of the side reactions is weak, which is conducive to reducing the generation of the silicon-containing product; on the other hand, the fluorinated solvent can form a dense and uniform solid electrolyte interface (SEI) film on the negative electrode tab, which plays a good protective role for the negative electrode tab. Optionally, 3 < b < 30, which can make the electrochemical device have better cycle performance and high-temperature storage performance. Exemplarily, the mass content b% of the fluorinated solvent can be 0.10%, 0.50%, 1%, 2%, 3%, 4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any value within a range consisting of any two of the above values.

[0060] In some embodiments, 0.1≤c≤5.0. When the mass content of the amine compound is within the above range, the amine solvent can sufficiently dissolve the silicon-containing product in the electrolyte, reduce the risk of local enrichment of the silicon-containing product on the positive current collector to cause local precipitation of active ions, such as local lithium precipitation, and thus can improve the cycle performance and high-temperature storage performance of the electrochemical device. Optionally, 0.8≤c≤4.0, which can make the electrochemical device have better cycle performance and high-temperature storage performance. For example, the mass content c% of the amine compound can be 0.1%, 0.5%, 0.8%, 1.1%, 2.2%, 3%, 3.5%, 4%, 5%, or any value within the range formed by any two of the above values.

[0061] The inventors have further found that by specifically selecting the fluorinated solvent and the amine compound, the cycle performance and high-temperature storage performance of the electrochemical device can be further improved.

[0062] In some embodiments, the fluorinated solvent can include a fluorinated carbonate and / or a fluorinated carboxylate.

[0063] For example, the fluorinated carbonate includes one or more of fluorinated ethylene carbonate, fluorinated propylene carbonate, fluorinated diethyl carbonate, difluorinated ethylene carbonate, di(trifluoromethyl) carbonate, di(pentafluoroethyl) carbonate, and di(2,2,2-trifluoroethyl) carbonate.

[0064] For example, the fluorinated carboxylate includes one or more of fluorinated methyl formate, fluorinated ethyl formate, fluorinated ethyl acetate, and fluorinated propyl acetate.

[0065] In some embodiments, the amine compound includes an organic amine compound and a salt thereof, i.e., the amine compound includes an organic amine compound and / or an organic amine salt.

[0066] As some examples, the organic amine compound and the salt thereof can include a compound represented by Formula (I) and a salt thereof,

[0067]

[0068] In Formula (I), R1and R2are each independently selected from a substituted or unsubstituted C1to C 10 a substituted or unsubstituted C2to C 10 a substituted or unsubstituted C2to C 10 a substituted or unsubstituted C1to C 10 an acyl group or a sulfonyl group; and when substituted, the substituent is a halogen atom.

[0069] Exemplarily, the organic amine compound includes one or more of bistrifluoromethanesulfonimide (CAS: 82113-65-3), trifluoromethanesulfonamide (CAS: 421-85-2), N,N-bis(pentafluoroethane sulfonate)imide (CAS: 152894-10-5), dimethanesulfonamide (CAS: 5347-82-0), bistrifluoroacetamide (CAS: 407-24-9), 2,2,2-trifluoro-N-(2,2,2-trifluoroethyl)acetamide, and 2,2,2-trifluoro-N-isopropylacetamide (CAS: 348-76-5).

[0070] Exemplarily, the organic amine salt includes magnesium bistrifluoromethanesulfonimide (CAS: 1019840-54-0) and / or 2-(trifluoroacetamido)ethylamine hydrochloride (CAS: 5458-14-0).

[0071] As further examples, the organic amine compound and the salt thereof can include a compound represented by Formula (II),

[0072]

[0073] In Formula (II), R3and R4are each independently selected from a substituted or unsubstituted alkyl group, or a substituted or unsubstituted cycloalkyl group, when substituted, the substituent is a halogen atom; or, R3and R4are each independently selected from a substituted or unsubstituted C1to C 20 alkyl group, or a substituted or unsubstituted C1to C 20 cycloalkyl group; M is selected from an alkali metal atom; or, M is selected from a sodium atom, a lithium atom, or a potassium atom.

[0074] Exemplarily, the organic amine compound and the salt thereof include one or more of lithium bisfluorosulfonimide LiN(SO2F)2, lithium bistrifluoromethanesulfonimide LiN(SO2CF3)2, and lithium bisfluorophosphonimide LiN(POF2)2.

[0075] As further examples, the organic amine compound and the salt thereof can include a compound represented by Formula (I) and the salt thereof, and a compound represented by Formula (II).

[0076] In some embodiments, the electrolyte further contains an electrolyte salt. The electrolyte salt is a well-known electrolyte salt suitable for use in electrochemical devices. Suitable electrolyte salts can be selected depending on the different electrochemical devices. For example, for lithium ion batteries, lithium salts are generally used as the electrolyte salt.

[0077] In some embodiments, the lithium salt comprises a fluorine-containing lithium salt, the fluorine-containing lithium salt comprises one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI). The fluorine-containing lithium salt has excellent ionic conductivity and electrochemical stability, which is beneficial to improve the kinetic performance and cycle stability of the electrochemical device. However, the fluorine-containing lithium salt can react with water in the electrolyte to produce hydrofluoric acid (HF), and HF can also react with silicon to produce silicon-containing products. The amine compound in the electrolyte of the present application can dissolve the silicon-containing products in the electrolyte, further improving the cycle performance and high-temperature storage performance of the electrochemical device.

[0078] Further, the molar concentration of the fluorine-containing lithium salt is denoted as N mol, and 0.8≤N≤1.4. When the molar concentration of the fluorine-containing lithium salt is in the above range, the ionic conductivity and electrochemical stability of the electrolyte can be improved, and the risk of side reaction between the fluorine-containing lithium salt and silicon can be reduced to a certain extent, thereby improving the cycle performance and high-temperature storage performance of the electrochemical device. Optionally, 1.0≤N≤1.3, which can make the electrochemical device have better cycle performance and high-temperature storage performance. Illustratively, the molar concentration N mol of the fluorine-containing lithium salt can be 0.8 mol, 0.9 mol, 1.0 mol, 1.2 mol, 1.3 mol, 1.4 mol, or a range formed by any two of the above values.

[0079] In some embodiments, the electrolyte further comprises a non-aqueous organic solvent. A single non-aqueous organic solvent can be used, or a plurality of non-aqueous organic solvents can be mixed. When mixed solvents are used, the mixing ratio can be controlled according to the desired performance of the electrochemical device.

[0080] In some embodiments, the electrolyte can further comprise a carbonate compound, a polynitrile compound, etc., for improving the performance of the electrolyte and forming a protective layer on the positive electrode sheet and / or the negative electrode sheet.

[0081] Illustratively, the carbonate compound comprises a linear carbonate compound and / or a cyclic carbonate compound. Illustratively, the linear carbonate compound comprises one or more of ethylallyl carbonate, diphenyl carbonate, methylallyl carbonate, and polycarbonate. Illustratively, the cyclic carbonate compound comprises one or more of vinylene carbonate, vinyl carbonate, propylene carbonate, vinyl ethylene carbonate, and dioctyl carbonate; optionally, the cyclic carbonate compound comprises vinyl carbonate and propylene carbonate.

[0082] It should be noted that the electrolyte in the present application can be directly taken from fresh preparation, or can be taken from the electrochemical device. An exemplary method of taking electrolyte from the electrochemical device includes the following steps: discharging the electrochemical device to the discharge cut-off voltage (for safety, the electrochemical device is generally in full discharge state), and then centrifuging. The liquid obtained after centrifugation is the electrolyte. The electrolyte can also be directly taken from the liquid inlet of the electrochemical device. The electrolyte is tested by gas chromatography-mass spectrometry (GC-MS) to detect the mass content of each component.

[0083] [Positive electrode sheet]

[0084] The positive electrode sheet is a positive electrode sheet known in the art that can be used in an electrochemical device. In some embodiments, the positive electrode sheet comprises a positive current collector and a positive active material layer. The positive active material layer is disposed on the surface of the positive current collector. The positive active material layer comprises a positive active material.

[0085] In some embodiments, the structure of the positive electrode sheet is a structure of a positive electrode sheet known in the art that can be used in an electrochemical device.

[0086] In some embodiments, the positive current collector is a metal, for example, an aluminum foil, and the aluminum foil contains silicon elements.

[0087] The positive electrode sheet has various coating methods, such as positive electrode single-sided coating, positive electrode double-sided coating, etc.

[0088] Positive electrode single-sided coating: the positive current collector includes two surfaces opposite to each other along its own thickness direction, for example, the two surfaces include a first surface and a second surface, and the positive active material layer can be disposed on one of the two surfaces, for example, the first surface, and the other surface, for example, the second surface, is a bare surface. The second surface can be directly in contact with the electrolyte, which has the risk of side reactions with silicon elements and fluorinated solvents in the electrolyte. Alternatively, the positive active material layer is only disposed on the first surface, but when disposed on the first surface, it partially covers the first surface, i.e., the first surface still has a bare part, which also has the risk of side reactions with the electrolyte. Figure 1 As shown in FIG. 1, the positive current collector 10 has a positive active material layer 20 disposed on one surface thereof.

[0089] The positive electrode double-sided coating: the positive electrode current collector includes two surfaces opposite to each other along the thickness direction of the positive electrode current collector, for example, the two surfaces include a first surface and a second surface. The positive electrode active material layer can also be provided on the two surfaces, the positive electrode active material layer can completely cover the first surface, partially cover the second surface, and the second surface has a bare surface which has a risk of directly contacting the electrolyte to cause a side reaction. Alternatively, the positive electrode active material layer can partially cover the first surface and partially cover the second surface, and the first surface and the second surface both have a bare surface which has a risk of directly contacting the electrolyte to cause a side reaction. When the positive electrode double-sided coating is used, the positive electrode double-sided coating is asymmetric coating, that is, the area covered by the positive electrode active material layer on the first surface and the area covered by the positive electrode active material layer on the second surface are not completely the same. Exemplarily, the area (bare surface) in the second surface which is not covered by the positive electrode active layer is denoted as S1, with the unit of μm 2 ; the area covered by the positive electrode active material layer in the second surface is denoted as S2, with the unit of μm 2 ; the electrochemical device satisfies: S1 / S2≥0.03; optionally, 0.05≤S1 / S2≤0.1. Under the above coating mode, the bare area of the positive electrode current collector is relatively large, and the exposed silicon content is relatively high, which is prone to cause a side reaction with the electrolyte to generate a silicon-containing product, and the amine compound can basically dissolve the silicon-containing product, thereby improving the cycle performance and high-temperature storage performance of the electrochemical device. As shown in Figure 2 , the positive electrode current collector 10 is provided with a positive electrode active material layer 20 on both surfaces, and one of the surfaces is partially covered by the positive electrode active material layer.

[0090] The positive electrode active material can be selected from various conventional materials known in the art which can reversibly intercalate and deintercalate active ions and can be used as the positive electrode active material of the electrochemical device. For a lithium ion battery, lithium ions are usually contained in the positive electrode active material; for a sodium ion battery, sodium ions are usually contained in the positive electrode active material. Next, the lithium ion is taken as an example for description.

[0091] In some embodiments, the positive electrode active material includes a positive electrode material capable of absorbing and releasing lithium, including but not limited to lithium cobaltate, lithium nickel cobalt manganese acid, lithium nickel cobalt aluminum acid, lithium manganate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate, lithium iron phosphate, lithium titanate, and lithium-rich manganese-based materials.

[0092] In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent. The positive electrode binder serves to improve the adhesion between the positive electrode active material particles and between the positive electrode active material particles and the current collector. In some embodiments, the positive electrode binder includes at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene oxide-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, nylon. The positive electrode conductive agent serves to provide conductivity to the electrode, which can include any electrically conductive material, as long as it does not cause chemical changes. In some embodiments, the positive electrode conductive agent includes at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, polyphenylene derivative. In some embodiments, the metal in the metal powder, metal fiber includes at least one of copper, nickel, aluminum, silver.

[0093] In some embodiments, the method of preparing the positive electrode tab is a method of preparing a positive electrode tab for an electrochemical device known in the art. In some embodiments, in the preparation of the positive electrode slurry, a solvent is generally added, the positive electrode active material is added to the binder and, as necessary, a conductive material and a thickening agent are added, and then dissolved or dispersed in the solvent to prepare a positive electrode slurry. The solvent is removed by evaporation during the drying process. The solvent is a solvent known in the art that can be used as a solvent for the positive electrode active material layer, such as, but not limited to, N-methylpyrrolidone (NMP).

[0094] [Positive electrode tab]

[0095] The negative electrode tab is a negative electrode tab known in the art that can be used for an electrochemical device. In some embodiments, the negative electrode includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is disposed on the surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material.

[0096] In some embodiments, the structure of the negative electrode tab is a structure of a negative electrode tab known in the art that can be used for an electrochemical device.

[0097] In some embodiments, the negative electrode current collector is a metal, such as, but not limited to, a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with an electrically conductive metal, or a combination thereof.

[0098] The negative electrode active material can be selected from various conventionally known materials that can reversibly intercalate and deintercalate active ions or conventionally known materials that can reversibly dope and dedope active ions, which can be used as a negative electrode active material for an electrochemical device.

[0099] In some embodiments, the negative active material includes at least one of lithium metal, lithium metal alloy, carbon material, material capable of doping / de-doping lithium, or transition metal oxide. In some embodiments, the carbon material can be selected from various carbon materials known in the art that can be used as carbon-based negative active materials for electrochemical devices. In some embodiments, the carbon material includes at least one of crystalline carbon or amorphous carbon. In some embodiments, the crystalline carbon is natural graphite or artificial graphite. In some embodiments, the shape of the crystalline carbon is amorphous, plate, flake, spherical, or fibrous. In some embodiments, the crystalline carbon is low crystalline carbon or high crystalline carbon. In some embodiments, the low crystalline carbon includes at least one of soft carbon or hard carbon. In some embodiments, the high crystalline carbon includes at least one of natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbead, mesophase pitch, high-temperature calcined carbon.

[0100] In some embodiments, the high-temperature calcined carbon is petroleum or coke derived from coal tar pitch. In some embodiments, the amorphous carbon includes at least one of soft carbon, hard carbon, mesophase pitch carbonization product, baked coke. In some embodiments, the negative active material includes transition metal oxide. In some embodiments, the transition metal oxide includes at least one of vanadium oxide or lithium vanadium oxide. In some embodiments, the negative active material includes at least one of Si, SiOx(0 < x < 2), Si / C composite, Si-Q alloy, Sn, SnOz, Sn-C composite, Sn-R alloy, where Q is selected from at least one of alkali metal, alkaline earth metal, Group 13 to Group 16 element, transition element, rare earth element, and Q is not Si, and R is selected from at least one of alkali metal, alkaline earth metal, Group 13 to Group 16 element, transition element, rare earth element, and R is not Sn. In some embodiments, Q and R include at least one of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po.

[0101] In some embodiments, the negative active material layer further comprises a negative binder and a negative conductive agent. In some embodiments, the negative binder comprises at least one of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, nylon. In some embodiments, the negative conductive agent is used to provide electrical conductivity to the electrode, which can include any electrically conductive material as long as it does not cause chemical changes. In some embodiments, the negative conductive agent comprises any one of carbon-based materials, metal-based materials, conductive polymers, or a mixture thereof. In some embodiments, the carbon-based materials comprise at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber. In some embodiments, the metal-based materials comprise at least one of metal powder or metal fiber of copper, nickel, aluminum, silver, etc. In some embodiments, the conductive polymers comprise polyphenylene derivatives.

[0102] In some embodiments, the method of preparing the negative electrode tab is a method of preparing a negative electrode tab for an electrochemical device known in the art. In some embodiments, in the preparation of the negative electrode slurry, a solvent is generally added, and the negative active material is dissolved or dispersed in the solvent after the binder is added and the conductive material and thickening agent are added as needed to prepare the negative electrode slurry. The solvent is removed by evaporation during the drying process. The solvent is a solvent known in the art that can be used as a solvent for the negative active material layer, such as, but not limited to, water. The thickening agent is a thickening agent known in the art that can be used as a thickening agent for the negative active material layer, such as, but not limited to, sodium carboxymethyl cellulose.

[0103] The present application does not have a particular limitation on the mixing ratio of the negative active material, the binder, and the thickening agent in the negative active material layer, and the mixing ratio thereof can be controlled according to the desired performance of the electrochemical device.

[0104] [Separator]

[0105] The separator is a separator known in the art that can be used for an electrochemical device, such as, but not limited to, a polyolefin microporous membrane. In some embodiments, the separator comprises at least one of polyethylene (PE), ethylene-propylene copolymer, polypropylene (PP), ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-methyl methacrylate copolymer.

[0106] In some embodiments, the separator is a single-layer separator or a multi-layer separator.

[0107] In some embodiments, the separator film is coated with a coating layer. In some embodiments, the coating layer comprises at least one of an organic coating layer and an inorganic coating layer, wherein the organic coating layer is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polyimide, acrylonitrile-butadiene copolymer, acrylonitrile-styrene-butadiene copolymer, polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, acrylate-styrene copolymer, polydimethylsiloxane, sodium polyacrylate, sodium carboxymethyl cellulose, and the inorganic coating layer is selected from at least one of SiO2, Al2O3, CaO, TiO2, ZnO2, MgO, ZrO2, SnO2.

[0108] The present application does not have a particular limitation on the form and thickness of the separator film. The preparation method of the separator film is a preparation method of a separator film that can be used for an electrochemical device and is known in the art.

[0109] Electronic device

[0110] Based on the same inventive concept, the present application also provides an electronic device.

[0111] The electronic device of the present application is any electronic device, for example, but not limited to, a notebook computer, a pen input type computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copying machine, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable audio player, a radio, a backup power supply, an electric motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, an illuminating appliance, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a household large storage battery, a lithium ion capacitor. Note that the electrochemical device of the present application is applicable not only to the above-mentioned electronic devices, but also to energy storage power stations, sea-borne vehicles, air-borne vehicles. The air-borne vehicles include air-borne vehicles within the atmosphere and air-borne vehicles outside the atmosphere.

[0112] In some embodiments, the electronic device comprises the electrochemical device of the present application.

[0113] The technical solutions of the present application are further described below with the lithium ion battery as an example and in combination with the comparative examples and the examples, but are not limited thereto. Those skilled in the art will understand that the preparation methods described in the present application are only exemplary embodiments, and any modification or substitution to the technical solutions of the present application without departing from the scope of the technical solutions of the present application shall be covered in the protection scope of the present application.

[0114] In the following examples and comparative examples, the reagents, materials and instruments used are commercially available or are obtained by synthesis, unless otherwise specified.

[0115] Examples

[0116] The following describes performance evaluation of examples and comparative examples of lithium ion batteries according to the present application.

[0117] Examples and Comparative Examples

[0118] Preparation of lithium ion batteries

[0119] (1) Preparation of positive electrode sheet

[0120] Lithium cobaltate (LiCoO2), conductive material (Super-P), and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 96:2:2 in an appropriate amount of N-methyl pyrrolidone (NMP) solvent, and stirred sufficiently to form a uniform positive electrode slurry. The positive electrode slurry was coated on a positive electrode current collector aluminum foil, dried, and cold-pressed to obtain a positive electrode active material layer. The positive electrode active material layer and the positive electrode current collector constituted a positive electrode sheet. The coating method of the positive electrode slurry is shown in Table 1.

[0121] (2) Preparation of negative electrode sheet

[0122] The negative electrode active material artificial graphite, the binder polyacrylic acid, and the thickening agent sodium carboxymethyl cellulose (CMC) were mixed in a weight ratio of 83.5:15:1.5 in an appropriate amount of deionized water solvent, and stirred sufficiently to form a uniform negative electrode slurry. The negative electrode slurry was coated on a negative electrode current collector copper foil, dried, and cold-pressed to obtain a negative electrode sheet.

[0123] (3) Preparation of electrolyte

[0124] In an argon atmosphere glove box with a water content of <10 ppm, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:1:1 to form a non-aqueous solvent. The lithium salt LiPF6 was dissolved in the non-aqueous solvent, and a certain amount of additives (succinonitrile SN, γ-butyrolactone GBL, etc.) were added to prepare an electrolyte. The additives are shown in Table 2.

[0125] (4) Preparation of separator

[0126] A polyethylene (PE) porous polymer film was used as the separator.

[0127] (5) Preparation of lithium ion battery

[0128] The positive electrode sheet, the separator film, and the negative electrode sheet are stacked in order, the separator film is between the positive electrode sheet and the negative electrode sheet to play a role of isolation, then the tab is welded and the electrode assembly is obtained by winding, the electrode assembly is placed in the outer packaging aluminum plastic film, the electrolyte prepared above is injected, and after vacuum packaging, standing, formation, shaping, capacity test and other processes, the soft package lithium ion battery is obtained.

[0129] Test method:

[0130] 1. Positive electrode sheet anomaly detection

[0131] The lithium ion battery after cycling is disassembled, and the abnormal area of the positive electrode sheet is observed. The abnormal area of the positive electrode sheet is cut and subjected to EDS element analysis test, if the Si element content is > 2%, it is judged that there is an abnormality in the positive electrode sheet (lithium ion battery failure), and the Si element content can be obtained at the same time.

[0132] EDS test procedure: the observed area of the positive electrode sheet is adhered to the sample table with conductive glue, and the observed area is marked in advance; after cleaning the surface, push it into the scanning electron microscope sample bin and make observation preparation; after the equipment is prepared, 3 or more abnormal areas in the suspected abnormal area can be randomly framed, the corresponding Si content can be obtained, and the average value is calculated to obtain the silicon content level of the sample.

[0133] 2. 85degC storage test method of lithium ion battery

[0134] (1) Adjust the voltage of the lithium ion battery to 3.8V to 3.9V, and test the thickness T1 of the lithium ion battery after the voltage is adjusted.

[0135] (2) Charge the lithium ion battery to the rated voltage at a current of 0.2C (C is the rated capacity of the lithium ion battery), and then charge at a constant voltage with a cutoff current of 0.05C.

[0136] (3) Place the lithium ion battery in an 85degC environment for 8 hours, and measure the thickness T2 of the lithium ion battery after cooling to room temperature.

[0137] (4) Thickness expansion rate = T2 / T1-1.

[0138] When the thickness expansion rate of the lithium ion battery is > 10%, the lithium ion battery is determined to be failed.

[0139] 3. Normal temperature cycling 400cls capacity retention rate test method of lithium ion battery

[0140] (1) Cycle the lithium ion battery at a rated current (rated power / rated voltage), and record the capacity C1 at the first full discharge.

[0141] (2) Record the discharge capacity C2 at the time of 400 cycles of lithium ion battery.

[0142] (3) Capacity retention rate = C2 / C1.

[0143] The capacity retention rate of lithium ion battery at room temperature is less than 85% after 400 cycles, and the lithium ion battery is determined to be invalid.

[0144] Test results:

[0145] The test results are shown in Tables 1 and 2.

[0146] Table 1

[0147]

[0148] Table 2

[0149]

[0150]

[0151] In Table 2, the content of Si element in the positive current collector (aluminum foil) incoming material is equivalent to a%.

[0152] The content of Si element in the abnormal area of the positive electrode plate refers to the content of Si element in the area obtained by testing the lithium ion battery after charge and discharge cycles.

[0153] The electrolyte in Comparative Example 1 does not introduce amine compounds, and the silicon-containing products generated by the side reaction between silicon elements in the positive current collector and fluorinated solvents cannot be effectively decomposed, causing an increase in the number of abnormal positive electrode plates and battery failure. Compared with Comparative Example 1, the electrolyte in Examples 1-16 introduces organic amine compounds, and by setting 0

[0154] When the contents of amine compounds, fluorinated solvents and silicon elements satisfy 0

[0155] When the mass content of the fluorinated solvent is 0.10% to 50%, the fluorinated solvent can form a dense and uniform solid-state electrolyte interface film on the negative electrode sheet, which has a good protective effect on the negative electrode sheet. When the mass content of the fluorinated solvent is 3% to 30%, the electrochemical device has better cycle performance and high-temperature storage performance.

[0156] When the addition amount of the amine compound is 0.1% to 5.0%, the film forming resistance is small, the polarization phenomenon of the lithium ion battery is alleviated, the silicon-containing by-product can be dissolved, and the cycle performance of the lithium ion battery is improved to a certain extent. In particular, when the addition amount of the amine compound is 0.8% to 4.0%, the cycle performance of the lithium ion battery can be further improved.

[0157] Although the illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments cannot be interpreted as a limitation of the present application, and changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrochemical device comprising a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer disposed on a surface of the positive electrode current collector, the positive electrode current collector containing silicon, the mass content of the silicon being a% based on the mass of the positive electrode current collector; the electrochemical device further comprising an electrolyte, the electrolyte comprising a fluorinated solvent and an amine compound, the mass content of the fluorinated solvent being b% and the mass content of the amine compound being c% based on the mass of the electrolyte, the electrochemical device satisfying 0 < a / c < 1 and 0 < b / c < 80.

2. The electrochemical device of claim 1, wherein, 0.3 ≤ a / c ≤ 0.7, and / or 15 ≤ b / c ≤ 65.

3. The electrochemical device of claim 1, wherein, the electrochemical device further satisfying 0 < a × b / c < 10.

4. The electrochemical device of claim 3, wherein, the electrochemical device further satisfying 1 ≤ a × b / c ≤ 9.

5. The electrochemical device of claim 1, wherein, the electrochemical device satisfying at least one of conditions (1) to (3): (1)0.03≤a≤0.18； (2)0.10≤b≤50； (3)0.1≤c≤5.0。 6. The electrochemical device of claim 5, wherein, 0.06≤a≤0.15。 7. The electrochemical device of claim 5, wherein, 3≤b≤30。 8. The electrochemical device of claim 5, wherein, 0.8≤c≤4.0。 9. The electrochemical device of claim 1, wherein, the fluorinated solvent comprising a fluorinated carbonate and / or a fluorinated carboxylic acid ester. 10.The electrochemical device according to claim 9, wherein the fluorinated carbonate comprises one or more of a fluorinated ethylene carbonate, a fluorinated propylene carbonate, a fluorinated diethyl carbonate, a difluorinated ethylene carbonate, a bis(trifluoromethyl)carbonate, a bis(pentafluoroethyl)carbonate, and a bis(2,2,2-trifluoroethyl)carbonate. 11.The electrochemical device according to claim 9, wherein the fluorinated carboxylic acid ester comprises one or more of a fluorinated methyl formate, a fluorinated ethyl formate, a fluorinated ethyl acetate, and a fluorinated propyl acetate.

12. The electrochemical device of claim 1, wherein, the amine compound comprises an organic amine compound and a salt thereof; the organic amine compound and the salt thereof comprise a compound represented by formula (I) and a salt thereof: in formula (I), R1and R2are each independently selected from a substituted or unsubstituted C1-C10 linear or cyclic alkyl group, a substituted or unsubstituted C2-C10 linear or cyclic alkenyl group, a substituted or unsubstituted C2-C10 linear or cyclic alkynyl group, a substituted or unsubstituted C1-C10 acyl group, a sulfonyl group; when substituted, the substituent is a halogen atom; and / or the organic amine compound and the salt thereof comprise a compound represented by formula (II): In formula (II), R3and R4are each independently selected from substituted or unsubstituted alkyl, or substituted or unsubstituted cycloalkyl, when substituted, the substituent is a halogen atom; alternatively, R3and R4are each independently selected from substituted or unsubstituted C1to C 20 alkyl, or substituted or unsubstituted C1to C 20 cycloalkyl; M is selected from an alkali metal atom.

13. The electrochemical device of claim 12, wherein, M is selected from a sodium atom, a lithium atom, or a potassium atom. 14.The electrochemical device according to claim 12, wherein the organic amine compound and the salt thereof comprise one or more of bistrifluoromethanesulfonylimide, trifluoromethanesulfonamide, N,N-bis(pentafluoroethane sulfonyl)imide, dimethanesulfonamide, bistrifluoroacetamide 2,2,2-trifluoro-N-(2,2,2-trifluoroethyl)acetamide, 2,2,2-trifluoro-N-isopropylacetamide, magnesium bistrifluoromethanesulfonylimide, and 2-(trifluoroacetamido)ethylamine hydrochloride; and / or the organic amine compound and the salt thereof comprise one or more of lithium bistrifluoromethanesulfonylimide LiN(SO2F)2, lithium bistrifluoromethanesulfonylimide LiN(SO2CF3)2, and lithium bistrifluoromethanesulfonylimide LiN(POF2)2.

15. The electrochemical device of claim 1, wherein, The electrolyte includes a fluorine-containing lithium salt, the fluorine-containing lithium salt including one or more of lithium hexafluorophosphate, lithium bis-trifluoromethanesulfonimide, and lithium bis(fluorosulfonyl)imide.

16. The electrochemical device of claim 15, wherein, The molar concentration of the fluorine-containing lithium salt is denoted as N mol, 0.8 ≤ N ≤ 1.

4.

17. The electrochemical device of claim 16, wherein, 1.0≤N≤1.3。 18. The electrochemical device of claim 1, wherein, The positive electrode active material layer is provided on one surface of the negative electrode current collector.

19. The electrochemical device of claim 1, wherein, The positive electrode active material layer is provided on both surfaces of the positive electrode current collector opposite each other in the thickness direction of the positive electrode current collector, and the positive electrode active material layer covers part of the two surfaces.

20. The electrochemical device of claim 19, wherein, The two surfaces include a first surface on which the positive electrode active material layer is provided and a second surface on part of which the positive electrode active material layer is provided. An area of the second surface not covered by the positive electrode active material layer is denoted as S1, in units of μm 2 ; The area of the second surface covered by the positive electrode active material layer is denoted as S2, in units of pm 2 ; The electrochemical device satisfies S1 / S2 ≥ 0.

03.

21. The electrochemical device of claim 20, wherein, 0.05 ≤ S1 / S2 ≤ 0.

1.

22. An electronic device including the electrochemical device according to any one of claims 1 to 21.

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