Lithium-ion batteries and electronic devices

Abstract

The present invention relates to a lithium ion battery (1) and an electronic device (10). The lithium ion battery (1) includes a negative electrode, a positive electrode, a separator, and an electrolyte. The positive electrode includes a positive electrode active material. The separator is provided between the negative electrode and the positive electrode. The electrolyte includes a cyclic sulfonic acid ester, and the cyclic sulfonic acid ester includes 1,3-propane sultone and a compound represented by formula (I) other than 1,3-propane sultone. Based on the mass n of the electrolyte, the content of the compound represented by formula (I) is A2%, and the value of A2 is in the range of 0.5 to 5. The provided electrolyte includes 1,3-propane sultone and the compound represented by formula (I). The mass A2 of the compound represented by formula (I) satisfies 0.5%≦A2 / n≦5%. 1,3-propane sultone and the compound represented by formula (I) can exert a synergistic effect, forming a dense CEI film layer on the surface of the positive electrode active material, thereby enhancing the protective effect on the positive electrode active material. [Formula 1] JPEG2025510350000037.jpg29144

Description

[Technical Field]

[0001] This invention relates to the field of energy storage technology, and more specifically to lithium-ion batteries and electronic devices. [Background technology]

[0002] Lithium-ion batteries are widely used in electronic products such as mobile phones, laptops, and cameras due to their characteristics such as high energy density, high operating voltage, and light weight. While the electrochemical properties of lithium-ion batteries are improved, their safety characteristics cannot be ignored. During use or transportation of lithium-ion batteries, side reactions may occur inside the battery, generating gaseous by-products. This can lead to excessively high pressure inside the lithium-ion battery, posing a safety risk.

[0003] Research has shown that electrolytes can undergo interfacial reactions with the positive and negative electrode active materials, and that these interfacial reactions have a significant impact on the electrochemical properties and structural stability of the positive and negative electrode materials, and can reduce gas generation to some extent. However, the protective effect of electrolytes on the positive and negative electrode active materials, especially the positive electrode active material, is still insufficient. Therefore, there is an urgent need to develop electrolytes that can effectively protect the active materials and thereby improve the safety characteristics of lithium-ion batteries. [Overview of the project]

[0004] The present invention provides a lithium-ion battery and an electronic device that can improve safety characteristics by reducing the amount of gas generated by the lithium-ion battery.

[0005] As a first aspect, the present invention proposes a lithium-ion battery including a negative electrode, a positive electrode, a separator, and an electrolyte. The positive electrode contains a positive electrode active material. The separator is provided between the negative electrode and the positive electrode. The electrolyte contains a cyclic sulfonic acid ester, and the cyclic sulfonic acid ester contains 1,3-propanesultone and a compound represented by formula (I) other than 1,3-propanesultone.

Chemical formula

[0006] In some embodiments of the present invention, the compound represented by formula (I) is a compound represented by formula (I-A) or a compound represented by formula (I-B).

Chemical formula

[0007] In some embodiments of the present invention, the compound represented by formula (IA) is one of the compounds represented by formulas (I-A1) to (I-A4). [ka]

[0008] In some embodiments of the present invention, the compound represented by formula (IB) is the compound represented by formula (I-B1) or the compound represented by formula (I-B2). [ka]

[0009] In some embodiments of the present invention, the compound represented by formula (I) is the compound represented by formula (IC), the compound represented by formula (ID), or the compound represented by formula (IE), [ka] Here, R 71 , R 72 , and R 73 Each is independently selected from a hydrogen atom, a halogen atom, and a C1-C2 alkyl group, and R 71 , R 72 , and R 73 It is impossible for both to be hydrogen atoms at the same time.

[0010] In some embodiments of the present invention, the compound represented by formula (IC) is one of the compounds represented by formulas (I-C1) to (I-C5). [ka]

[0011] In some embodiments of the present invention, the compound represented by formula (ID) is the compound represented by formula (I-D1). [ka]

[0012] In some embodiments of the present invention, the compound represented by formula (IE) is the compound represented by formula (I-E1). [ka]

[0013] In some embodiments of the present invention, based on the mass n of the electrolyte, the mass of 1,3-propanesultone is A1, and the mass A1 of 1,3-propanesultone and the mass A2 of the compound represented by formula (I) satisfy 0.5 ≤ A2 / A1 ≤ 8.0.

[0014] In some embodiments of the present invention, the mass n of the electrolyte and the mass m of the lithium-ion battery satisfy 7% ≤ n / m ≤ 15%, and optionally, 10 ≤ n / m ≤ 15. Based on the mass n of the electrolyte, the mass of 1,3-propanesultone is A1, and the mass A1 of 1,3-propanesultone and the mass m of the lithium-ion battery satisfy 0.01% ≤ A1 / m ≤ 0.1%.

[0015] In some embodiments of the present invention, the electrolyte further comprises a carboxylic acid ester additive. Based on the mass n of the electrolyte, the mass percentage y of the carboxylic acid ester additive is 5% ≤ y ≤ 60%, and the mass percentage y of the carboxylic acid ester additive, the mass A1 of 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.05 ≤ (A1 + A2) / (n × y) ≤ 0.6, and optionally, 0.1 ≤ (A1 + A2) / (n × y) ≤ 0.3.

[0016] In some embodiments of the present invention, the carboxylic acid ester additive includes one or more of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, ethyl difluoroethyl acetate, and ethyl trifluoroethyl acetate.

[0017] In some embodiments of the present invention, the electrolyte further comprises a carbonate ester additive. The carbonate ester additive comprises fluoroethylene carbonate and / or vinylene carbonate. Based on the mass n of the electrolyte, the mass percentage z of the carbonate ester additive is 0.5% ≤ z ≤ 15%, and the mass percentage z of the carbonate ester additive, the mass A1 of 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.1 ≤ (A1 + A2) / (n × z) ≤ 7, and optionally, 0.2 ≤ (A1 + A2) / (n × z) ≤ 1.1.

[0018] In some embodiments of the present invention, the electrolyte further comprises a polynitrile additive. The polynitrile additive is used to complex with cations in the positive electrode active material during charging and discharging of the lithium-ion battery. Based on the mass n of the electrolyte, the mass percentage r of the polynitrile additive is 0.1% ≤ r ≤ 12%, and optionally 0.5% ≤ r ≤ 8%.

[0019] The polynitrile additives in lithium-ion batteries include one or more compounds from among those represented by formulas (II-1) to (II-4). [ka] In formulas (II-1) to (II-4), R 21 C1-C is either substituted or unsubstituted. 12 Alkylene group, and substituted or unsubstituted C1-C 12 Selected from alkylene oxy groups, R 31 , R 32 These are, independently, a covalent single bond and a substituted or unsubstituted C1-C bond. 12 Selected from alkylene groups, R 41 , R 42 , and R 43 These are, independently, covalent single bonds, substitutional or unsubstituted C1-C bonds. 12 Alkylene group, and substituted or unsubstituted C1-C 12 Selected from alkylene oxy groups, R 51 C1-C is either substituted or unsubstituted. 12 Alkylene group, substituted or unsubstituted C2-C 12 Alkenylene group, substituted or unsubstituted C6-C 26 Arylene group, and substituted or unsubstituted C2-C 12 Selected from heterocyclylene groups, Here, R 21 , R 31 , R 32 , R 41 , R 42 , R 43 , and R 51 If at least one of them is substituted, the substituent is a halogen atom.

[0020] In some embodiments of the present invention, the negative electrode, separator, and positive electrode are wound along the winding direction to form a wound structure, and the wound structure includes two ends facing each other along the winding direction and an intermediate portion located between the two ends, and the lithium-ion battery further includes a case and a connecting layer, the case containing an electrolyte and the wound structure, the connecting layer including a first surface and a second surface facing each other along its own thickness direction, the first surface connecting the intermediate portion and the end of the two ends closer to the case, and the second surface connecting to the case.

[0021] In some embodiments of the present invention, the connecting layer is a hot-melt adhesive layer or a composite film layer including a hot-melt adhesive layer.

[0022] In some embodiments of the present invention, the material of the hot-melt adhesive layer includes one or more of polyolefins, polyolefin copolymers, polyamides, polyurethanes, and epoxy resins.

[0023] In some embodiments of the present invention, the polyolefin includes polyethylene and / or polypropylene, and the polyolefin copolymer includes one or more of the following: ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-(ethylene-butylene)-styrene copolymer, and styrene-(ethylene-propylene)-styrene copolymer.

[0024] In a second aspect, the present invention provides an electronic device comprising a lithium-ion battery of any embodiment in the first aspect of the present invention.

[0025] According to the electrolyte provided in the embodiments of the present invention, the electrolyte comprises 1,3-propanesultone and a compound represented by formula (I). Both of these compounds can undergo a reductive ring-opening reaction on the surface of the positive electrode active material so as to stably form a CEI film layer on the surface of the positive electrode active material. This CEI film layer can provide protection to the positive electrode active material, thereby reducing the risk of side reactions between the positive electrode active material and other substances in the electrolyte, and thereby reducing the risk of gaseous by-products being generated when side reactions occur. Furthermore, the mass A2 of the compound represented by formula (I) satisfies 0.5% ≤ A2 / n ≤ 5%, and 1,3-propanesultone and the compound represented by formula (I) can exert a synergistic effect, forming a dense CEI film layer on the surface of the positive electrode active material, thereby further enhancing the protective effect on the positive electrode active material. [Brief explanation of the drawing]

[0026] In the following, necessary drawings illustrating embodiments of the present invention or the prior art will be described in general terms. Clearly, the drawings described below represent only a portion of embodiments of the present invention. Those skilled in the art can, without creative effort, still derive drawings of other embodiments from the structures illustrated in these drawings. [Figure 1]Figure 1 is a schematic diagram of a lithium-ion battery provided in some embodiments of the present invention. [Figure 2] Figure 2 is a schematic diagram of the combination of the winding structure and connecting layer of the lithium-ion battery shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram of an electronic device provided in some embodiments of the present invention. The drawing is not drawn to actual scale. The reference numerals in the drawing are as follows: 1 Lithium-ion battery 11 Connecting layer 12 Case 13 Winding structure; 131 End; 132 Middle section 10 Electronic device [Modes for carrying out the invention]

[0027] The embodiments of the present invention will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions will be denoted by the same reference numerals. The drawings relating to the embodiments described herein are illustrative and schematic and are used to provide a basic understanding of the invention. The embodiments of the present invention should not be construed as limiting the invention.

[0028] In this specification, quantities, ratios, and other numerical values ​​may be expressed in range form. Such range forms are used for convenience and conciseness and should be understood to include not only clearly defined numerical values ​​that specify range limits, but also all individual numerical values ​​or subranges within that range, as clearly specifying each numerical value and subrange.

[0029] In the embodiments and claims for carrying out the invention, a list of items connected by the terms “one or more of,” “one or more of,” “one or more of,” or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means A only, B only, or A and B. In other examples, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means A only, B only, C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0030] The term "alkyl group" includes linear and branched alkyl groups. For example, an alkyl group is C1-C 50 Alkyl alkyl group, C1-C 40 Alkyl alkyl group, C1-C 30 Alkyl alkyl group, C1-C 20 Alkyl alkyl group, C1-C 12 Alkyl alkyl group, C1-C 10 The alkyl group can be an alkyl group, a C1-C6 alkyl group, or a C1-C4 alkyl group. In some examples, the alkyl group includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, and the like. The alkyl group may be optionally substituted.

[0031] The term "alkylene group" refers to a group formed by the loss of two hydrogen atoms from the same carbon atom of an alkane, or by the loss of one hydrogen atom from each of two different carbon atoms. For example, an alkylene group is C1-C 50 Alkylene group, C1-C 40 Alkylene group, C1-C 30 Alkylene group, C1-C 20Alkylene group, C1-C 12 Alkylene group, C1-C 10 The alkylene group can be an alkylene group, a C1-C6 alkylene group, or a C1-C4 alkylene group. In some examples, the alkylene group includes a methylene group (-CH2-), an ethylene group, a 1,2-ethylene group, a propylene group, a 1,2-propylene group, a butylene group, a 1,2-butylene group, a 1,3-butylene group, a 1,4-butylene group, a pentylene group, a 1,2-pentylene group, and the like. The alkylene group may be optionally substituted.

[0032] The term "alkenyl group" includes both linear and branched alkenyl groups. For example, an alkenyl group is C2-C 50 Alkenyl group, C2-C 40 Alkenyl group, C2-C 30 Alkenyl group, C2-C 20 Alkenyl group, C2-C 12 Alkenyl group, C2-C 10 The alkenyl group can be an alkenyl group, a C2-C6 alkenyl group, a C2-C6 alkenyl group, or a C2-C4 alkenyl group. In some examples, the alkenyl group includes vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl groups. The alkenyl group may be optionally substituted.

[0033] The term "alkenylene group" refers to a group that has lost a hydrogen atom from the carbon atom of an alkene. For example, an alkenylene group is C2-C 50 Alkenylene group, C2-C 40 Alkenylene group, C2-C 30 Alkenylene group, C2-C 20 Alkenylene group, C2-C 12 Alkenylene group, C2-C 10The alkenylene group can be an alkenylene group, a C2-C6 alkenylene group, a C2-C6 alkenylene group, or a C2-C4 alkenylene group. In some examples, the alkenylene group includes vinylene, propenylene, butenylene, pentenylene, hexenylene, heptenylene, octenylene, and the like. The alkenylene group may be optionally substituted.

[0034] The term "alkylene oxy group" refers to a group consisting of an alkyl group that has lost a hydrogen atom and an oxygen atom. For example, an alkylene oxy group is C1-C 50 Alkylene oxy group, C1-C 40 Alkylene oxy group, C1-C 30 Alkylene oxy group, C1-C 20 Alkylene oxy group, C1-C 12 Alkylene oxy group, C1-C 10 The alkylene oxy group can be an alkylene oxy group, a C1-C6 alkylene oxy group, a C1-C4 alkylene oxy group, or a C1-C2 alkylene oxy group. In some examples, the alkylene oxy group includes a methylene oxy group, an ethylene oxy group, a propylene oxy group, and the like. The alkylene oxy group may be optionally substituted.

[0035] The term "aryl group" refers to a closed aromatic ring or ring system. For example, an aryl group is a C6-C ring. 50 Aryl group, C6-C 40 Aryl group, C6-C 30 Aryl group, C6-C 20 Aryl group, C6-C 10 It can be an aryl group. For example, C6-C 30 An aryl group refers to a group containing 6 to 30 carbon atoms to form a ring. In some examples, aryl groups include phenyl, naphthyl, phenanthryl, anthryl, biphenyl, triphenylene, pyrenyl, spirobifluorenyl, perilenyl, indenyl, and azulenyl groups.

[0036] The term "halogen atom" refers to atoms such as fluorine, chlorine, and bromine.

[0037] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In each example, "hydrogen" can be 1H (protium, H).

[0038] Throughout this specification, substituents of compounds are disclosed in groups or ranges. It is explicitly anticipated that any combination of members of such groups and ranges is included in the present invention. For example, the term "C1-C8 alkyl group" clearly indicates that it will disclose individual C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7, and C7-C8 alkyl groups.

[0039] As another example, integers in the range 5 to 40 are clearly expected to reveal the individuals 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. Integers in the range 1 to 20 are clearly expected to reveal the individuals 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Based on this, other groups or ranges can be clearly expected.

[0040] If the group is substituted, the substituent is independently selected from alkyl groups, aryl groups, halogen atoms, cyano groups-CN, and combinations thereof.

[0041] In high-temperature environments or during charge-discharge cycles, the positive electrode active material in lithium-ion batteries can irreversibly crack. After the positive electrode active material cracks, a new crystal plane is exposed. When the exposed crystal plane comes into contact with the electrolyte, the crystal plane and the electrolyte undergo a side reaction, generating gaseous by-products. These gaseous by-products increase the gas pressure within the lithium-ion battery, posing a safety risk to the battery.

[0042] In view of this, the present invention has designed the electrolyte composition from the viewpoint of protecting the cathode active material. A cathode protective additive such as a cyclic sulfonic acid ester is added to the electrolyte in order to form a cathode electrolyte interface (CEI) film on the surface of the cathode active material, and the amount of cyclic sulfonic acid ester used is adjusted to reduce the risk of side reactions occurring between the cathode active material and the electrolyte. Next, the technical proposal of the present invention will be described in detail.

[0043] In a first aspect, the present invention proposes a lithium-ion battery.

[0044] As shown in Figure 1, the lithium-ion battery 1 includes a negative electrode, a positive electrode, a separator, and an electrolyte. The positive electrode includes a positive electrode active material. The separator is provided between the negative electrode and the positive electrode. The electrolyte includes a cyclic sulfonic acid ester, and the cyclic sulfonic acid ester includes 1,3-propanesultone (PS) and a compound represented by formula (I) other than 1,3-propanesultone. [ka] In formula (I), R 11 These are selected from substituted or unsubstituted C1-C4 alkylene groups and substituted or unsubstituted C2-C4 alkenylene groups. R 12 These are covalent single bonds, substituted or unsubstituted C1-C2 alkylene oxy groups, -O-, and -R 13 -SO2-R 14 - Selected from, R 13is selected from a substituted or unsubstituted C1-C2 alkylene group, R 14 is selected from a covalent single bond, a substituted or unsubstituted C1-C2 alkylene group, and -O-, R 11 R 12 R 13 and R 14 when at least one of them is substituted, the substituent is a C1-C 20 alkyl group, a C6-C 30 aryl group, a halogen atom, or -CN, wherein the cyclic sulfonic acid ester is used to cause a reductive ring-opening reaction on the surface of the positive electrode active material during charging and discharging of the lithium ion battery 1, Based on the mass n of the electrolyte solution, the mass A2 of the compound represented by formula (I) satisfies 0.5% ≤ A2 / n ≤ 5%.

[0045] According to the electrolyte solution of the embodiment of the present invention, both 1,3-propanesultone and the compound represented by formula (I) can cause a reductive ring-opening reaction on the surface of the positive electrode active material so as to stably form a CEI film layer on the surface of the positive electrode active material. Since the CEI film layer can exert a protective effect on the positive electrode active material, the risk of side reactions occurring between the positive electrode active material and other substances in the electrolyte solution is reduced, and thereby the risk of generating gaseous by-products when side reactions occur can be reduced. Further, the mass A2 of the compound represented by formula (I) satisfies 0.5% ≤ A2 / n ≤ 5%. 1,3-propanesultone and the compound represented by formula (I) can exert a synergistic effect, form a dense CEI film layer on the surface of the positive electrode active material, and thereby further enhance the protective effect on the positive electrode active material.

[0046] In some embodiments, the compound represented by formula (I) can include a compound represented by formula (I-A),

Chemical formula

[0047] Exemplarily, the compound represented by the formula (I-A) is any one of the compounds represented by the formula (I-A1) to the formula (I-A4).

Chemical formula

[0048] In some other embodiments, the compound represented by the formula (I) can include the compound represented by the formula (I-B).

Chemical formula

[0049] Exemplarily, the compound represented by the formula (I-B) is the compound represented by the formula (I-B1) or the compound represented by the formula (I-B2).

Chemical formula

[0050] In some further other embodiments, the compound represented by the formula (I) can include the compound represented by the formula (I-C).

Chemical formula

[0051] For example, the compound represented by formula (IC) may be one of the compounds represented by formulas (I-C1) to (I-C3). [ka]

[0052] In some further embodiments, the compound represented by formula (I) may include the compound represented by formula (ID), [ka] Here, R 71 This is selected from hydrogen atoms, halogen atoms, and C1-C2 alkyl groups.

[0053] For example, the compound represented by formula (ID) may be the compound represented by formula (I-D1). [ka]

[0054] In some yet other embodiments, the compound represented by formula (I) may include the compound represented by formula (IE), [ka] Here, R 71 This is selected from hydrogen atoms, halogen atoms, and C1-C2 alkyl groups.

[0055] For example, the compound represented by formula (IE) may be the compound represented by formula (I-E1). [ka]

[0056] In some embodiments, based on the mass n of the electrolyte, the mass of 1,3-propanesultone is A1, and the mass A1 of 1,3-propanesultone and the mass A2 of the compound represented by formula (I) satisfy 0.5 ≤ A2 / A1 ≤ 8.0, and furthermore, 0.5 ≤ A2 / A1 ≤ 8.0. By adjusting the mass of 1,3-propanesultone and the compound represented by formula (I) to satisfy the above content range, the stability of film formation can be further enhanced, and the cycle stability of the lithium-ion battery 1 can be improved. It is also possible to maintain the cycle stability of the lithium-ion battery 1 while reducing the amount of 1,3-propanesultone used.

[0057] In some embodiments, the mass n of the electrolyte and the mass m of the lithium-ion battery 1 satisfy 7% ≤ n / m ≤ 15%, and furthermore, 10 ≤ n / m ≤ 15. Based on the mass n of the electrolyte, the mass of 1,3-propanesultone is A1, and the mass A1 of 1,3-propanesultone and the mass m of the lithium-ion battery 1 satisfy 0.01% ≤ A1 / m ≤ 0.1%. The mass n of the electrolyte and the mass A1 of 1,3-propanesultone in the electrolyte are adjusted according to the mass m of the lithium-ion battery 1, thereby enhancing the film formation effect of 1,3-propanesultone on the surface of the positive electrode active material. In this specification, n / m may be the electrolyte retention coefficient.

[0058] In some embodiments, to improve the electrochemical properties of the lithium-ion battery 1, the electrolyte further comprises a carboxylic acid ester additive. Based on the mass n of the electrolyte, the mass percentage y of the carboxylic acid ester additive is 5% ≤ y ≤ 60%, and the mass percentage y of the carboxylic acid ester additive, the mass A1 of 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.05 ≤ (A1 + A2) / (n × y) ≤ 0.6, and further, 0.1 ≤ (A1 + A2) / (n × y) ≤ 0.3. During the charge-discharge cycle of the lithium-ion battery 1, the carboxylic acid ester additive can ensure the transport of metal ions, thereby improving the cycle characteristics of the lithium-ion battery 1. Furthermore, the cycle characteristics of the lithium-ion battery 1 can be further improved by synergistically adjusting the amounts used of the carboxylic acid ester additive, 1,3-propanesultone, and the compound represented by formula (I) to satisfy the above range.

[0059] For example, carboxylic acid ester additives include one or more of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, ethyl difluoroethyl acetate, and ethyl trifluoroethyl acetate.

[0060] During the charge-discharge cycle, the negative electrode active material contained in the lithium-ion battery 1 may undergo a side reaction with the electrolyte, potentially reducing the electrochemical properties of the lithium-ion battery 1. To further improve the electrochemical properties of the lithium-ion battery 1, in some embodiments, the electrolyte further includes a carbonate ester additive. The carbonate ester additive is used to cause polymerization or decomposition reactions during the charge-discharge of the lithium-ion battery 1. Based on the mass n of the electrolyte, the mass percentage z of the carbonate ester additive is 0.5% ≤ z ≤ 15%, and the mass percentage z of the carbonate ester additive, the mass A1 of the 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.1 ≤ (A1 + A2) / (n × z) ≤ 7, and optionally, 0.2 ≤ (A1 + A2) / (n × z) ≤ 1.1. During the charging and discharging process of lithium-ion battery 1, the carbonate ester additive can form a solid electrolyte interface (SEI) film on the surface of the negative electrode active material, thereby protecting the negative electrode active material. Furthermore, by synergistically adjusting the amounts of the carbonate ester additive, the mass A1 of 1,3-propanesultone, and the compound represented by formula (I), the cycle characteristics and storage characteristics of lithium-ion battery 1 can be improved.

[0061] Exemplary examples of carbonate ester additives include fluoroethylene carbonate (FEC) and / or vinylene carbonate (VC).

[0062] In some embodiments, the electrolyte further comprises a polynitrile-based additive. The polynitrile-based additive is used to complex with cations in the positive electrode active material during the charging and discharging of the lithium-ion battery 1. Based on the mass n of the electrolyte, the mass percentage r of the polynitrile-based additive is 0.1% ≤ r ≤ 12%, and further, 0.5% ≤ r ≤ 8%. During the charging and discharging process of the lithium-ion battery 1, the polynitrile-based additive can complex with the positive electrode active material, thereby forming a film layer on the surface of the positive electrode active material, and thus providing further protection to the positive electrode active material. Furthermore, by synergistically adjusting the polynitrile-based additive to satisfy the above range, the cycle characteristics of the lithium-ion battery 1 can be further improved.

[0063] In some embodiments, the positive electrode includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being provided on the surface of the positive electrode current collector. The positive electrode current collector may be one of those commonly used in the art and may include, but are not limited to, aluminum foil or nickel foil. The positive electrode active material layer includes a positive electrode active material. Exemplarily, the positive electrode active material includes, but is not limited to, lithium cobaltate, lithium manganeseate, lithium nickelate, etc., and can be selected as needed. Lithium ions can be reversibly intercepted and released from the positive electrode active material.

[0064] To enhance the bonding force between positive electrode active materials, in some embodiments, the positive electrode active material layer may further contain a binder. This can bond adjacent positive electrode active materials and increase the bonding force between the positive electrode active material layer and the positive electrode current collector. Exemplary examples of binders include, but are not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) styrene-butadiene rubber, epoxy resin, nylon, and the like.

[0065] In some embodiments, to enhance the conductivity of the positive electrode active material layer, the positive electrode active material layer may further contain a conductive agent. In some embodiments, to enhance the conductivity of the positive electrode active material layer, the conductive agent may include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fibers, etc.), metallic materials (e.g., metal powders, metal fibers, etc., including copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.

[0066] 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 being provided on the surface of the negative electrode current collector. The negative electrode current collector may be one of those commonly used in the art and may include, but are not limited to, copper foil, nickel foil, or titanium foil. The negative electrode active material layer includes a negative electrode active material. Exemplary examples of the negative electrode active material include, but are not limited to, carbonaceous materials, siliconaceous materials, alloying materials, lithium metal-containing composite oxide materials, etc. Non-limiting examples of carbonaceous materials include crystalline carbon, amorphous carbon, and mixtures thereof. Crystalline carbon may be amorphous or sheet-type, flake-type, spherical, or fibrous natural or artificial graphite. Amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, etc., and can be selected as needed. The negative electrode active material can be, for example, natural graphite, artificial graphite, mesocarbon microbeads (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, or lithium-ionized TiO2-Li4Ti5O with a spinel structure. 12 It is at least one of the Li-Al alloys. Lithium ions can be reversibly intercepted and released from the negative electrode active material.

[0067] In some embodiments, in addition to the negative electrode active material, the negative electrode active material layer further includes a binder and a conductive agent. The binder and conductive agent in the negative electrode can be the same materials as those described for the positive electrode active material layer, and these will not be discussed in detail here.

[0068] In some embodiments, the separator includes a polymer or inorganic material made of a material stable to the electrolyte. The inorganic material may include inorganic ceramic particles. Exemplarily, the inorganic ceramic particles may include one or more selected from the group consisting 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. Exemplarily, the polymer material may include one or more of polyamides, polyacrylonitriles, acrylic acid ester polymers, polyacrylic acid, polyacrylates, polyvinylpyrrolidone, polyvinyl ethers, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene), or one or more selected from the group consisting of these.

[0069] The negative electrode, separator, and positive electrode in the lithium-ion battery 1 have multiple structural forms. For example, the negative electrode, separator, and positive electrode are stacked in order and provided in a stacked sheet structure, or the negative electrode, separator, and positive electrode are wound to form a wound structure 13. Specifically, the negative electrode, separator, and positive electrode are wound along the winding direction to form a wound structure 13, and the wound structure 13 includes two ends 131 facing each other along the winding direction, and an intermediate portion 132 located between the two ends 131.

[0070] As shown in Figures 1 and 2, in some embodiments, the lithium-ion battery 1 further includes a case 12 and a connecting layer 11. The case 12 contains the electrolyte and the winding structure 13, and the connecting layer 11 includes a first surface and a second surface facing each other along its own thickness direction, the first surface connecting the intermediate portion 132 and the end 131 of the two ends 131 that is closer to the case 12, and the second surface connecting to the case 12. By connecting the intermediate portion 132 and the end 131 of the two ends 131 that is closer to the case 12, the connecting layer 11 fixes the winding structure 13, thereby reducing the risk of unwinding or expansion of the winding structure 13 and reducing the risk of gas accumulation inside the winding, and the gas is discharged from the lithium-ion battery 1 in a timely manner, thereby improving the safety characteristics of the lithium-ion battery 1. Furthermore, the connecting layer enhances the connection strength between the winding structure 13 and the case 12 by connecting the winding structure 13 and the case 12, reducing the risk of separator shrinkage and slippage of the winding structure 13 after the lithium-ion battery 1 generates gas during high-temperature storage, thereby improving the structural stability of the lithium-ion battery 1. In addition, by connecting the case 12 and the winding structure 13 with the connecting layer 11 and incorporating one or more of the cyclic sulfonic acid ester, carboxylic acid ester additive, carbonate ester additive, and polynitrile additive added to the electrolyte, the safety characteristics of the lithium-ion battery 1 during intermittent cycling can be improved.

[0071] As some examples, the connecting layer 11 may be a hot-melt adhesive SIS layer or a composite film layer including a hot-melt adhesive layer. The composite film layer may have a hot-melt adhesive layer, a metal layer, and a hot-melt adhesive layer laminated in sequence along its own thickness direction, or it may be a plurality of hot-melt adhesive layers. For example, the material of the hot-melt adhesive layer includes one or more of polyolefins, polyolefin copolymers, polyamides, polyurethanes, and epoxy resins. For example, the polyolefin includes polyethylene and / or polypropylene. Exemplarily, the polyolefin copolymer includes one or more of ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, styrene-isoprene-styrene copolymers, styrene-butadiene-styrene copolymers, styrene-(ethylene-butylene)-styrene copolymers, and styrene-(ethylene-propylene)-styrene copolymers. The metal layer may be an aluminum layer, a magnesium layer, etc.

[0072] It should be understood that the lithium-ion battery 1 of the present invention can include all types of primary or secondary batteries. In particular, the lithium-ion battery 1 is a lithium secondary battery that includes a lithium metal secondary battery, a lithium-ion secondary battery, a lithium polymer secondary battery, or a lithium-ion polymer secondary battery.

[0073] The applications of the lithium-ion battery 1 of the present invention are not particularly limited and can be used in any known applications in the prior art.

[0074] As shown in Figure 3, the lithium-ion battery 1 of the present invention can be used in electronic devices 10. Herein, the electronic devices 10 include, but are not limited to, laptop computers, pen-input computers, mobile computers, e-book players, mobile phones, portable facsimile machines, portable copiers, portable printers, stereo headsets, video recorders, LCD televisions, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, auxiliary bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors.

[0075] The technical aspects of the present invention will be further explained below with reference to comparative examples and embodiments, using lithium-ion batteries as an example; however, the present invention is not limited thereto. Those skilled in the art should understand that the preparation methods described in the present invention are merely exemplary embodiments, and any modifications or equivalent substitutions made without departing from the scope of the technical aspects of the present invention are all within the scope of protection of the present invention.

[0076] Examples Preparation of lithium-ion batteries The positive electrode active material in the examples and comparative examples was prepared into a lithium-ion total battery using the following preparation method.

[0077] (1) Preparation of the positive electrode Lithium cobalt oxide (LiCoO2), the positive electrode active material, Super P, the conductive agent, and polyvinylidene fluoride (PVDF), the binder, were mixed in a weight ratio of 97:1:2. N-methylpyrrolidone (NMP) was added, and the mixture was uniformly stirred using a vacuum blender to obtain a positive electrode slurry. The positive electrode slurry was uniformly applied to aluminum foil, which served as the positive electrode current collector. The aluminum foil was dried, then cold-pressed, punched out, cut, and vacuum-dried to obtain the positive electrode.

[0078] (2) Preparation of the negative electrode A negative electrode slurry was obtained by mixing synthetic graphite, the negative electrode active material, sodium carboxymethylcellulose (CMC), the thickener, and styrene-butadiene rubber (SBR), the binder, in a weight ratio of 97:1:2, adding deionized water, and using a vacuum blender. The negative electrode slurry was uniformly applied to copper foil, which was the negative electrode current collector, and the copper foil was dried. After that, it was cold-pressed, punched out, cut, and then vacuum-dried to obtain the negative electrode.

[0079] (3) Preparation of electrolyte In a glove box under a dry argon gas atmosphere, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:3:6. Additives were added and dissolved, and after thorough stirring, the lithium salt LiPF6 was added and mixed uniformly to obtain the electrolyte. The concentration of LiPF6 was 1.20 mol / L. The specific types and contents of the additives used in the electrolyte are shown in Tables 1 to 5. Here, wt% is the mass percentage calculated based on the total mass n of the electrolyte.

[0080] (4) Preparation of separators To form a coating layer slurry, boehmite and polyacrylic acid ester were mixed and dissolved in deionized water. Then, the coating layer slurry was uniformly applied to both surfaces of the porous substrate by microgravure coating, and a drying process was performed to obtain the desired isolation film.

[0081] (5) Preparation of lithium-ion batteries The positive electrode, separator, and negative electrode were stacked in sequence, with the separator interposed between them to provide isolation. The stack was then wound, tabs were welded, and a bare cell was obtained. The bare cell was placed in an aluminum-plastic film, which served as the outer foil. The prepared electrolyte was injected, and a soft-package lithium-ion battery was obtained through processes such as vacuum sealing, standing, formation, molding, and capacity grading. This battery did not include a protective plate or pack package.

[0082] Characteristic measurement (1) Method for measuring the mass of the electrolyte The battery was discharged at 0.1C with a constant current until it reached 2.8V, and its weight was measured and recorded as m. The battery was then disassembled, and the bare cells and the aluminum plastic film outer foil were rapidly extracted in high-purity acetonitrile (purity ≥ 99.9%). The supernatant obtained from the extraction was measured by gas chromatography to obtain the relative content of each component in the electrolyte. The bare cells and aluminum plastic film outer foil were dried in a vacuum oven after extraction, and their total mass was measured and recorded as m'. The mass n of the electrolyte was given by n = m - m', and the actual mass of each component in the battery was the product of n and the relative content of each component. For example, A1 = n × (relative content of PS).

[0083] (2) Interval Cycle (ITC) measurement of lithium-ion batteries The lithium-ion battery was placed in a constant temperature chamber at 45°C and left undisturbed for 30 minutes. Then, the lithium-ion battery was discharged at a current of 0.5C until it reached 3.0V, and then charged at a current of 1C until it reached 4.5V. This was followed by a 24-hour period of undisturbed charging and discharging, which constituted one charge-discharge cycle. This charge-discharge cycle was repeated 50 times. The initial discharge capacity was denoted as C, and the discharge capacity after 100 cycles as C'. The cycle capacity retention rate was calculated using the formula (C' / C) × 100%. The initial thickness of the lithium-ion batteries in the examples and comparative examples was measured with a micrometer and denoted as η. The thickness of the lithium-ion batteries in the examples and comparative examples after 50 charge-discharge cycles was measured with a micrometer and denoted as η'. The rate of change in the thickness of the lithium-ion batteries was calculated using the formula (η' / η-1) × 100%.

[0084] (3) Measurement of high-temperature storage of lithium-ion batteries A lithium-ion battery was left standing for 5 minutes at room temperature (25°C), charged at 1C until the voltage reached 4.5V, then charged at a constant voltage of 0.05C, and left standing for 30 minutes. The initial thickness of the battery was measured and recorded as η1. Subsequently, the lithium-ion battery was stored in a high-temperature furnace at 60°C for 50 days, and the thickness of the battery was measured at the end of the measurement and recorded as η1'. The rate of change in the thickness of the lithium-ion battery was calculated using the formula (η1' / η1-1)×100%.

[0085] Results of characteristic measurement

[0086] [Table 1]

[0087] As can be seen from the characteristic measurement results in Table 1, by adding PS to the electrolyte and controlling the proportion of PS in the lithium-ion battery, it is possible to improve the ITC capacity retention rate and the thickness increase rate.

[0088] Comparing Examples 1-1 to 1-3 with Comparative Examples 1-1 to 1-3, it can be seen that as the mass of the lithium-ion battery increases, the electrolyte retention coefficient does not change, but the ITC capacity retention rate and thickness increase rate deteriorate significantly. This is because as the mass of the lithium-ion battery increases, the contact area between the positive electrode active material, the negative electrode active material and the electrolyte increases, the consumption reaction of active lithium in the ITC cycle deteriorates, and when the protection for the positive electrode fails, the number of sites where gas generation reactions occur increases.

[0089] Comparing Examples 1-4 to 1-9 with Example 1-2, it can be seen that when the electrolyte retention coefficient n / m increases, the increase in ITC thickness deteriorates significantly. However, if the electrolyte retention coefficient n / m is within a suitable range, the ITC capacity retention rate can be improved, and the optimal value is found to be between 7% and 15%. This is because, when the electrolyte retention coefficient increases, although the PS mass does not change, ethylene carbonate solvent and lithium hexafluorophosphate also participate in the film formation reaction. This protects the structural stability of the negative electrode material to some extent and improves the capacity retention rate. However, if the protection for the positive electrode is insufficient, the solvent undergoes a decomposition reaction, increasing the amount of electrolyte, which in turn worsens gas generation and lithium ion intercalation / release reactions. As can be seen from Examples 1-9 to 1-10, when the electrolyte retention coefficient n / m exceeds 15%, further increasing the PS does not have a very desirable effect.

[0090] A comparison of Examples 1-11 to 1-15 with Example 1-2 shows that PS has good positive and negative electrode film formation properties. However, due to regulatory restrictions, there is an upper limit to the proportion of PS in the cell A1 / m, which must be ≤0.1%. Therefore, it is not possible to further improve ITC by further increasing the amount of PS.

[0091] By comparing Examples 1-16 to 1-21 with Comparative Examples 1-1 to 1-3, it can be seen that when the mass of the battery differs, considering the legally mandated mass percentage limit, the absolute value of the upper limit of PS usage will differ, and the optimal value of the electrolyte retention coefficient may also change, but it will basically be distributed between 7% and 15%.

[0092] [Table 2]

[0093] As can be seen from the characteristic measurement results in Table 2, by adding the compound shown in formula (I) to the electrolyte and controlling its content to 5% ≥ A2 / n ≥ 0.5%, it is possible to achieve both an improvement in ITC capacity retention rate and an improvement in thickness increase rate.

[0094] By comparing Comparative Examples 2-1 to 2-2 with Examples 1-8, it can be seen that, compared to PS, the compound represented by formula (I) is involved in the formation of positive and negative electrode films and can suppress the increase in thickness.

[0095] By comparing Examples 2-1 to 2-21 with Example 1-8, it can be seen that by using PS and the compound represented by formula (I) in combination, the ITC capacity retention rate can be further improved and the thickness increase rate can be further improved.

[0096] By comparing Examples 1-20, 2-3 with Examples 2-22 to 2-25, it can be seen that while the optimal value of A2 / A1 may change when the battery mass is different, it basically falls within the range of 0.5 to 8.0.

[0097] [Table 3]

[0098] Comparative Examples 3-1 and 3-2 are comparative examples in this specification, provided for the convenience of comparison with other data in Table 3. Comparative Examples 3-1 and 3-2 are still included within the scope of protection of the present invention.

[0099] As can be seen from the characteristic measurement results in Table 3, by introducing a carboxylic acid ester additive into the electrolyte and optimizing the amount of carboxylic acid ester used in combination with PS and the compound shown in formula (I), the ITC capacity retention rate and thickness increase rate can be improved within a certain range.

[0100] In contrast to Example 2-9, Comparative Examples 3-1 to 3-2 introduce carboxylic acid ester additives alone, and if the electrolyte retention amount is inappropriate, this can actually worsen the ITC capacity retention rate or thickness increase rate.

[0101] Compared to Examples 2-9, Comparative Example 3-3, although it incorporates a carboxylic acid ester, does not incorporate the compound shown in formula (I), which significantly worsens the ITC capacity retention rate. Carboxylic acid ester additives have lower viscosity than carbonate esters, and an appropriate amount of carboxylic acid ester is advantageous for lithium ion transport. In particular, if the electrolyte retention rate is too high, it reduces the risk of delayed lithium ion release reactions due to high electrolyte viscosity, accumulation on the surface of the active material, and irreversible reactions, thereby ensuring the battery's capacity retention rate. However, because the chemical stability of the carboxylic acid ester itself in the positive and negative electrodes is insufficient, if the carboxylic acid ester content is too high, the consumption of active lithium in the repair of SEI and CEI is accelerated, and if the protection to the positive electrode fails, it indirectly leads to gas generation due to solvent decomposition. Therefore, the risk of gas generation can be reduced by controlling the content of the carboxylic acid ester additive within an appropriate range.

[0102] Compared to Examples 2-9, in Examples 3-4 and 3-12 to 3-16, different carboxylic acid esters had different effects on ITC and thickness increase rate. When compared using the same amount, propyl propionate was more advantageous in terms of volume retention rate, and ethyl difluoroethyl was more advantageous in terms of thickness increase rate. This demonstrates that a balanced improvement in ITC characteristic indicators can be achieved in a diversified carboxylic acid ester solvent system (a mixture of multiple types of carboxylic acid ester additives).

[0103] In contrast to Examples 2-9, in Examples 3-1 to 3-18, the carboxylic acid ester additive is combined with PS and the compound represented by formula (I), and the content range of these three must be controlled to 60%≧y≧5%, 0.05≦(A1+A2) / (n×y)≦0.6, preferably 0.1≦(A1+A2) / (n×y)≦0.3. If the content of the carboxylic acid ester additive is too low, a smooth lithium ion transport pathway cannot be provided, while if the content of the carboxylic acid ester additive is too high, the electrolyte protection to the positive electrode becomes insufficient, and the solvent is more likely to decompose and be consumed.

[0104] [Table 4-1] [Table 4-2]

[0105] Comparative Examples 4-1 and 4-2 are comparative examples in this specification, provided for the convenience of comparison with other data in Table 4. Comparative Examples 4-1 and 4-2 are still included within the scope of protection of the present invention.

[0106] As can be seen from the characteristic measurement results in Table 4, by introducing a carbonate ester-based additive into the electrolyte and optimizing the amount of this additive used in combination with PS and the compound shown in formula (I), the ITC capacity retention rate and thickness increase rate can be improved within a certain range. ITC can also be improved by introducing a polynitrile-based additive into the electrolyte and controlling the range of the amount of this additive used.

[0107] Compared to Example 3-16, in Examples 4-1 to 4-10, the negative electrode film formation can be repaired by introducing a carbonate ester-based additive, and the ITC capacity retention rate can be improved by controlling the carbonate ester-based additive content within the range of 1% to 10%. The different carbonate ester-based additives, FEC and VC, have different optimal values, but when (A1+A2) / (n×z)≧0.2%, both can achieve improvement in ITC.

[0108] In Example 4-10, compared to Comparative Examples 4-1 to 4-3, there is an interaction between the electrolyte retention coefficient, PS, the compound represented by formula (I), and the carbonate ester additive. By adjusting their content, the carbonate ester additive repairs the negative electrode film, improves the cycle characteristics of the lithium cobalt oxide battery, and provides beneficial effects for cycling and storage.

[0109] Compared to Example 3-16, Examples 4-11 to 4-25 significantly improve ITC gas generation without impairing ITC capacity retention by introducing polynitrile additives and controlling their content to 0.1% to 12%. While the optimal values ​​for different nitrile additives vary, a preferred range is 0.5% to 8%. If the polynitrile content is too low, protection to the positive electrode becomes insufficient, leading to significant ITC gas generation. On the other hand, if the polynitrile content is too high, the viscosity of the electrolyte decreases significantly, delaying the lithium ion release reaction and worsening the capacity retention rate. When comparing the same usage amounts, trinitrile additives show significantly greater improvement in ITC gas generation than dinitrile additives, and the deterioration of capacity in excess is also more serious.

[0110] Compared to Example 3-16, Examples 4-26 to 4-33 exhibit a mutually restraining relationship in terms of properties between the electrolyte retention coefficient, PS, the compound represented by formula (I), the carbonate ester additive, and the nitrile additive. When the relationship 0.1 ≤ (A1 + A2) / (n × z) ≤ 7 is satisfied, and the PS meets the legal requirements, the ITC characteristics are significantly improved compared to the comparative examples in Table 1. Here, preferably, the relationship 0.2 ≤ (A1 + A2) / (n × z) ≤ 1.1 is satisfied.

[0111] [Table 5]

[0112] In Table 5, the negative electrode tail adhesive connects the end of the negative electrode closest to the case and the middle section to reduce the risk of the bare cell unwinding after winding. The U-shaped adhesive bonds the bottom of the bare cell after winding to reduce the risk of a safety accident caused by the separator shrinking after high-temperature storage and measurement, which could lead to contact between the positive and negative electrodes. The SIS hot melt adhesive is a double-sided tape that acts as a connecting layer, bonding the bare cell and the case after winding.

[0113] As can be seen from the characteristic measurement results in Table 5, compared to Example 4-26, Examples 5-1 to 5-3 all used a negative electrode tail portion adhesive, and in particular Example 5-3 also used SIS hot melt adhesive as a connecting layer. The negative electrode tail portion adhesive and SIS hot melt adhesive reduce the shrinkage of the separator and the slippage of the bare cell after gas generation due to high-temperature storage, and can reduce the risk of serious safety accidents caused by gas expansion, leakage, combustion, etc. Furthermore, the combination of the above structural design and electrolyte design can enhance the safety characteristics in intermittent cycles of the battery and achieve effects that cannot be obtained by simply adjusting the electrolyte additives and solvents.

[0114] Compared to Example 4-32, in the batteries of Examples 5-3 to 5-4, the increase in ITC thickness cannot be suppressed simply by adjusting the electrolyte additives and solvents. However, by using U-shaped adhesive and SIS hot melt adhesive and combining them with the electrolyte design, the ITC characteristics can be further improved.

[0115] While exemplary embodiments have been described and explained, those skilled in the art should understand that the embodiments described above are not intended to limit the present invention, and that modifications, substitutions, and changes to the embodiments are permitted as long as they do not depart from the spirit, principles, and scope of the invention.

Claims

1. Lithium-ion battery, The lithium-ion battery comprises a negative electrode, a positive electrode, a separator, and an electrolyte. The positive electrode includes a positive electrode active material. The separator is provided between the negative electrode and the positive electrode. The aforementioned electrolyte contains a cyclic sulfonic acid ester, The cyclic sulfonic acid ester includes 1,3-propanesultone and a compound represented by formula (I) other than 1,3-propanesultone. 【Chemistry 1】 In formula (I), R １１ C is either substituted or non-substituted. １ -C ４ Alkylene group, and substituted or unsubstituted C ２ -C ４ Selected from alkenylene groups, R １２ is selected from a shared single bond, a substituted or unsubstituted C １ -C ２ alkyleneoxy group, -O-, and -R １３ -SO ２ -R １４ -; R １３ C is either substituted or non-substituted. １ -C ２ Selected from alkylene groups, R １４ C is a covalent single bond, substitution, or non-substitution. １ -C ２ Selected from alkylene groups and -O-, R １１ , R １２ , R １３ , and R １４ If at least one of them is substituted, the substituent is C １ -C ２０ alkyl group, C ６ -C ３０ It is an aryl group, a halogen atom, or -CN, The compound represented by formula (I) is the same compound represented by formula (I-A1), 【Chemistry 2】 The mass of the 1,3-propanesultone is A1, and the mass of the compound represented by formula (I) is A2, and the mass A1 of the 1,3-propanesultone and the mass A2 of the compound represented by formula (I) satisfy 1.0 ≤ A2 / A1 ≤ 3.

0. A lithium-ion battery in which, based on the mass n of the electrolyte, the mass A2 of the compound represented by formula (I) satisfies 0.5% ≤ A2 / n ≤ 5%.

2. The electrolyte further contains a carboxylic acid ester additive, The lithium-ion battery according to claim 1, wherein, based on the mass n of the electrolyte, the mass percentage y of the carboxylic acid ester additive is 5% ≤ y ≤ 60%, and the mass percentage y of the carboxylic acid ester additive, the mass A1 of the 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.05 ≤ (A1 + A2) / (n × y) ≤ 0.

6.

3. The lithium-ion battery according to claim 2, wherein the mass percentage y of the carboxylic acid ester additive, the mass A1 of the 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.1 ≤ (A1 + A2) / (n × y) ≤ 0.

3.

4. The lithium-ion battery according to claim 2 or 3, wherein the carboxylic acid ester additive comprises one or more of ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, ethyl difluoroethyl acetate, and ethyl trifluoroethyl acetate.

5. The electrolyte further contains a carbonate ester-based additive, The aforementioned carbonate ester additive includes fluoroethylene carbonate and / or vinylene carbonate. A lithium-ion battery according to any one of claims 1 to 4, wherein, based on the mass n of the electrolyte, the mass percentage z of the carbonate ester additive is 0.5% ≤ z ≤ 15%, and the mass percentage z of the carbonate ester additive, the mass A1 of the 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.1 ≤ (A1 + A2) / (n × z) ≤ 7.

6. The lithium-ion battery according to claim 5, wherein the mass percentage z of the carbonate ester additive, the mass A1 of the 1,3-propanesultone, and the mass A2 of the compound represented by formula (I) satisfy 0.2 ≤ (A1 + A2) / (n × z) ≤ 1.

1.

7. The electrolyte further contains a polynitrile-based additive, The polynitrile-based additive is used to undergo a complex reaction with the cation in the positive electrode active material during the charging and discharging of the lithium-ion battery. Based on the mass n of the electrolyte, the mass percentage r of the polynitrile additive is 0.1% ≤ r ≤ 12%. The aforementioned polynitrile additive includes one or more compounds from among those represented by formulas (II-1) to (II-4), 【Transformation 3】 In formulas (II-1) to (II-4), R ２１ C is either substituted or non-substituted. １ -C １２ Alkylene group, and substituted or unsubstituted C １ -C １２ Selected from alkylene oxy groups, R ３１ , R ３２ These are, independently, a covalent single bond and a substituted or unsubstituted C. １ -C １２ Selected from alkylene groups, R ４１ , R ４２ , and R ４３ Each of these is independently a covalent single bond, substitution, or unsubstituted C. １ -C １２ Alkylene group, and substituted or unsubstituted C １ -C １２ Selected from alkylene oxy groups, R ５１ C is either substituted or non-substituted. １ -C １２ Alkylene group, substituted or unsubstituted C ２ -C １２ Alkenylene group, substituted or unsubstituted C ６ -C ２６ Arylene group, and substituted or unsubstituted C ２ -C １２ Selected from heterocyclylene groups, Here, R ２１ , R ３１ , R ３２ , R ４１ , R ４２ , R ４３ , and R ５１ The lithium-ion battery according to any one of claims 1 to 6, wherein if at least one of the substituents is substituted, the substituent is a halogen atom.

8. The lithium-ion battery according to claim 7, wherein the mass percentage r of the polynitrile additive is 0.5% ≤ r ≤ 8% based on the mass n of the electrolyte.

9. The negative electrode, the separator, and the positive electrode are wound along the winding direction to form a wound structure, and the wound structure includes two ends facing each other along the winding direction, and an intermediate portion located between the two ends. The lithium-ion battery according to any one of claims 1 to 8, further comprising a case and a connecting layer, wherein the case contains the electrolyte and the winding structure, and the connecting layer includes a first surface and a second surface facing each other along its own thickness direction, the first surface connecting the intermediate portion and the end of the two ends closer to the case, and the second surface connecting to the case.

10. The lithium-ion battery according to claim 9, wherein the connecting layer is a hot-melt adhesive layer or a composite film layer including a hot-melt adhesive layer.

11. The lithium-ion battery according to claim 10, wherein the material of the hot-melt adhesive layer comprises one or more of polyolefins, polyolefin copolymers, polyamides, polyurethanes, and epoxy resins.

12. The polyolefin comprises polyethylene and / or polypropylene, The lithium-ion battery according to claim 11, wherein the polyolefin copolymer includes one or more of the following: ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, styrene-isoprene-styrene copolymer, styrene-butadiene-styrene copolymer, styrene-(ethylene-butylene)-styrene copolymer, and styrene-(ethylene-propylene)-styrene copolymer.

13. An electronic device comprising a lithium-ion battery according to any one of claims 1 to 12.

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