Non-aqueous electrolyte for secondary batteries, secondary batteries, and power consumption devices

Abstract

This application provides a non-aqueous electrolyte for secondary batteries, a secondary battery, and a power consumption device. The non-aqueous electrolyte for secondary batteries of this application comprises an additive and a non-aqueous solvent containing dimethyl carbonate, the additive comprising a cyclic sulfate ester compound represented by formula (I). [Formula 1] JPEG2026518323000040.jpg44170

Description

[Technical Field]

[0001] This application relates to the technology of lithium batteries, and more particularly to non-aqueous electrolytes for secondary batteries, secondary batteries, and power consumption devices. [Background technology]

[0002] In recent years, as the range of applications for secondary batteries has expanded significantly, they are now widely used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in multiple fields including power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the rapid development of secondary batteries, higher requirements are being demanded for their DCR, cycle characteristics, and storage performance. [Overview of the Initiative]

[0003] This application has been made in view of the above-mentioned problems, and its purpose is to provide a non-aqueous electrolyte for secondary batteries, a secondary battery, and a power consumption device. By adopting the non-aqueous electrolyte of this application, the DCR of the battery is improved, the cycle characteristics and storage performance of the battery are improved, the amount of gas generated during battery cycling is reduced, and the rate characteristics of the battery are improved.

[0004] To achieve the above objective, a first aspect of the present application provides a non-aqueous electrolyte for a secondary battery comprising an additive and a non-aqueous solvent containing dimethyl carbonate. The aforementioned additive includes a cyclic sulfate ester compound represented by formula (I), [ka] However, R 1 , R 2 , R 3 and R 4Each is independently selected from any one of a group having a structure represented by formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, n1 and n2 are each independently any integer from 0 to 2,

Chemical formula

[0005] Accordingly, in this application, the non-aqueous electrolyte is formed by blending dimethyl carbonate with an additive. The non-aqueous electrolyte of this application has superior high-pressure resistance, and during the initial charging process of the battery, the additive forms a CEI film on the positive electrode surface that has higher stability and a stronger ability to block electrons, having an inorganic-organic hybrid structure. This suppresses side reactions between the electrolyte and the positive electrode, thereby improving the battery's DCR, enhancing the battery's cycle characteristics and storage performance, and reducing gas generation during battery cycling. Dimethyl carbonate can reduce the viscosity of the electrolyte, improve the conductivity of the electrolyte, and consequently improve the battery's rate characteristics.

[0006] In any embodiment, the cyclic sulfate ester compound has the structure represented by formula (I-1), [ka] R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group. [ka] R 5 and R 6 Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group.

[0007] In the general formula (I-1) above, the rings of the cyclic sulfate esters are all five-membered rings, which allows for the formation of a denser CEI film. Compared to six-membered rings, five-membered rings have greater ring strain, making them easier to deposit at the positive electrode. However, six-membered rings have less ring strain and higher stability, resulting in slower film formation at the positive electrode. This leads to lower efficiency in generating an electron-blocking CEI film, which affects the effectiveness of the CEI film.

[0008] In any embodiment, R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group, R 5 and R 6 Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group. Preferably, R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group, R 5 and R 6Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group. More preferably, R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, R 5 and R 6 Each of these is independently selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group. More preferably, the base of the structure represented by the general formula (II-1) is [ka] One of the following is selected, where X is a F atom, a Cl atom, or a Br atom.

[0009] In any embodiment, R 1 , R 2 , R 3 and R 4 Each is independent of the others. [ka] X is selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group, and X is an F atom. Preferably, R 1 , R 2 , R 3 and R 4 Each is independent of the others. [ka] X is selected from one of the following: a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, and X is a fluorine atom.

[0010] In any embodiment, the cyclic sulfate ester compound is, [ka] Selected from.

[0011] The above-mentioned method for producing cyclic sulfate ester compounds is simple and advantageous for industrial dissemination and implementation. Furthermore, the improvement effect on the battery's cycle characteristics is more stable.

[0012] In any embodiment, the mass content of the additive in the non-aqueous electrolyte is 0.001% to 15%, preferably 0.005% to 10%, and more preferably 0.05% to 5%.

[0013] When the mass content of additives in the non-aqueous electrolyte is within the above range, the high-pressure resistance of the electrolyte is further improved, and the stability and electron-blocking ability of the CEI coating on the positive electrode are further enhanced, thereby suppressing side reactions between the electrolyte and the positive electrode. This improves the battery's DCR, enhances its cycle characteristics and storage performance, and reduces the amount of gas generated during battery cycling.

[0014] In any embodiment, the mass content of the dimethyl carbonate in the non-aqueous solvent is 5% to 80%, preferably 10% to 70%, and more preferably 20% to 50%.

[0015] When the mass content of dimethyl carbonate in the non-aqueous solvent is within the above range, the DCR of the battery is further improved, the cycle characteristics and storage performance of the battery are enhanced, the amount of gas generated during battery cycling is reduced, the viscosity of the electrolyte is further reduced, the conductivity of the electrolyte is improved, and consequently the rate characteristics of the battery are enhanced.

[0016] A second aspect of the present application further provides a battery comprising a non-aqueous electrolyte, a positive electrode sheet, and a negative electrode sheet according to the first aspect of the present application, wherein the negative electrode sheet comprises a negative electrode active material, and preferably the secondary battery is a lithium secondary battery.

[0017] Accordingly, in this invention, the non-aqueous electrolyte is formed by blending dimethyl carbonate with an additive. The electrolyte of this invention has superior high-pressure resistance, and during the initial charging process of the battery, the additive forms a CEI film on the positive electrode surface that has higher stability and a stronger ability to block electrons, having an inorganic-organic hybrid structure. This suppresses side reactions between the electrolyte and the positive electrode, improves the battery's DCR, and enhances the battery's cycle characteristics and storage performance. Dimethyl carbonate can reduce the viscosity of the electrolyte, improve the conductivity of the electrolyte, and consequently improve the battery's rate characteristics.

[0018] In all embodiments, the resistance of the positive electrode sheet is 15Ω or less, preferably 8Ω or less.

[0019] Therefore, this improves the stability and safety of the battery system, while simultaneously providing the battery with good dynamic characteristics, improving the battery's DCR, enhancing the battery's cycle characteristics and storage performance, reducing gas generation during battery cycling, and further improving the battery's rate characteristics.

[0020] In any embodiment, the volume-average particle size Dv50 of the negative electrode active material is 3 to 30 μm, preferably 6 to 20 μm, and more preferably 8 to 15 μm.

[0021] Having the volume-average particle size Dv50 of the negative electrode active material within the above range forms a stable SEI film on the negative electrode surface, reduces side reactions between the electrolyte and the negative electrode active material, reduces gas generation during battery cycling, and contributes to improving the battery's cycle characteristics and storage performance. Improving the battery's DCR is advantageous in reducing the degree of polarity of the battery and improving the battery's capacity.

[0022] In any embodiment, the positive electrode sheet contains a positive electrode active material. Preferably, the positive electrode active material is Li 1+x Ni a Co b M 1-a-b O 2-y A y and includes, provided that M includes one or more elements selected from Mn, Fe, Cr, Ti, Zn, V, Al, Zr, Ce, Mg, Ga, Cu, and Nb. Preferably, M may include one or two elements selected from Mn and Al. A includes one or more elements selected from S, F, Cl, and I. Preferably, A may include one or two elements selected from S and F. -0.1 ≦ x ≦ 0.2, 0 < a < 1. Preferably, 0.5 ≦ a < 1. More preferably, 0.7 ≦ a ≦ 0.9. 0 < b < 1. Preferably, 0 < b < 0.5. More preferably, 0 < b ≦ 0.2, 0 < a + b < 1, 0 ≦ y < 0.2.

[0023] The third aspect of the present application provides a power consumption device including a non-aqueous electrolyte for a secondary battery according to the first aspect of the present application or a secondary battery according to the second aspect of the present application.

Brief Description of Drawings

[0024] [Figure 1] It is a schematic diagram of a secondary battery according to an embodiment of the present application. [Figure 2] It is an exploded view of a secondary battery according to an embodiment of the present application shown in FIG. 1. [Figure 3] It is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 4] It is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 5] It is an exploded view of a battery pack according to an embodiment of the present application shown in FIG. 4. [Figure 6] It is a schematic diagram of a power consumption device using a secondary battery according to an embodiment of the present application as a power source.

Explanation of Reference Numerals

[0025] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module, 5: Rechargeable battery, 51: Housing, 52: Electrode assembly, 53: Top cover assembly. [Modes for carrying out the invention]

[0026] Embodiments specifically disclosing the non-aqueous electrolyte for secondary batteries, secondary batteries, battery modules, battery packs, and power consumption devices of this application will be described in detail with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters or redundant explanations of substantially identical structures may be omitted. This is to avoid making the following explanation unnecessarily long and to facilitate understanding for those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0027] The “range” disclosed herein is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, the selected lower and upper limits defining the boundaries of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Similarly, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are listed, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are all intended. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as being an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] All embodiments and optional embodiments of this application can be combined to form new technical solutions unless otherwise specified.

[0029] All of the technical features and selectable technical features of this application can be combined to form new technical solutions, unless otherwise specified.

[0030] Unless otherwise specified, all steps of this invention may be performed sequentially or randomly, preferably in order. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if the method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0031] As used in this application, “includes” and “inclusive” refer to both open and closed forms unless otherwise specified. For example, “includes” and “inclusive” may include or include other components not listed, or may include or include only the listed components.

[0032] In this application, unless otherwise specified, the term “or” is inclusive. For example, the phrase “A or B” means “A, B, or both A and B.” More specifically, the condition “A or B” is satisfied by either A being true (or existing) and B being false (or not existing), A being false (or not existing) and B being true (or existing), or both A and B being true (or existing).

[0033] In this application, unless otherwise specified, the term "halogen" refers to elemental atoms of Group VIIA, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and others.

[0034] In this application, unless otherwise specified, the term "C1-C6 alkyl group" refers to a linear or branched alkyl group having 1 to 6 carbon atoms. Specifically, it includes C1-C3 alkyl groups and C2-C4 alkyl groups, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, or n-hexyl group.

[0035] In this application, unless otherwise specified, the term "C1-C6 haloalkyl group" refers to a C1-C6 alkyl group in which one or more H atoms are substituted with halogens, provided that "C1-C6 alkyl group" and "halogen" are as defined above. Specifically, this includes C1-C3 haloalkyl groups and C2-C4 haloalkyl groups, such as monofluoromethyl groups, difluoromethyl groups, trifluoromethyl groups, and 2,2,2-trifluoroethyl groups.

[0036] In this application, unless otherwise specified, the term "C1-C6 alkoxy group" refers to a C1-C6 alkyl-O- group, where "C1-C6 alkyl group" is as described above. Non-limiting examples of suitable C1-C6 alkoxy groups include methoxy, ethoxy, and isopropoxy.

[0037] In this application, unless otherwise specified, the term "C1-C6 haloalkoxy group" refers to a C1-C6 alkoxy group in which one or more H atoms are substituted with halogens, where "C1-C6 alkoxy group" and "halogen" are defined as above. Specifically, this includes C1-C3 haloalkoxy groups and C2-C4 haloalkoxy groups, such as difluoromethoxy, trifluoromethoxy, and 2,2,2-trifluoroethoxy.

[0038] In this application, unless otherwise specified, the term "C2-C6 alkenyl group" refers to a monovalent hydrocarbon group having 2 to 6 carbon atoms and possessing at least one unsaturated carbon-carbon double bond, either in a straight or branched chain. Specifically, this includes C2-C5 alkenyl groups and C2-C4 alkenyl groups, such as ethylene, propylene, n-butene, isobutylene, n-pentene, and isopentene.

[0039] In this application, unless otherwise specified, the term "C2-C6 ester group" refers to "-COO-C1-C6 alkyl group," where "C1-C6 alkyl group" is as described above. Specifically, this includes C2-C5 ester groups and C2-C4 ester groups, such as -COOCH3 and -COOCH2CH3.

[0040] [Secondary battery] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be used continuously by recharging after they have been discharged, thereby activating the active material.

[0041] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g., lithium ions) reciprocate between the positive and negative electrode sheets, being inserted and removed. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes while also allowing active ions to pass through. The electrolyte primarily serves to conduct active ions between the positive and negative electrode sheets.

[0042] [Non-aqueous electrolyte for secondary batteries] One embodiment of the present application provides a non-aqueous electrolyte for a secondary battery comprising an additive and a non-aqueous solvent containing dimethyl carbonate. The aforementioned additive includes a cyclic sulfate ester compound represented by formula (I), [ka] However, R 1 , R 2 , R 3 and R 4Each is independently selected from any one of a group having a structure represented by formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, n1 and n2 are each independently an arbitrary integer from 0 to 2, for example, 0, 1, or 2,

Chemical formula

[0043] The mechanism is not clear. However, the applicant of the present application has found that in the present application, the non-aqueous electrolyte is formed by blending dimethyl carbonate and an additive, and the electrolyte of the present application has better high-pressure resistance performance. During the first charging process of the battery, the additive forms a CEI film having a more stable and stronger ability to block electrons on the surface of the positive electrode, which is an inorganic and organic hybrid. To suppress the side reaction between the electrolyte and the positive electrode, the DCR of the battery is improved, the cycle characteristics and storage performance of the battery are improved, the amount of gas generated during the cycle of the battery is reduced, dimethyl carbonate reduces the viscosity of the electrolyte, improves the conductivity of the electrolyte, and thus can improve the rate characteristics of the battery.

[0044] In some embodiments, the cyclic sulfate compound has a structure represented by the formula (I-1), [Chemical formula] R 1 , R 2 , R 3 and R 4Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group. [ka] R 5 and R 6 Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group.

[0045] In the general formula (I-1) above, the rings of the cyclic sulfate esters are all five-membered rings, which allows for the formation of a denser CEI film. Compared to six-membered rings, five-membered rings have greater ring strain, making them easier to deposit at the positive electrode. However, six-membered rings have less ring strain and higher stability, resulting in slower film formation at the positive electrode. This leads to lower efficiency in generating an electron-blocking CEI film, which affects the effectiveness of the CEI film.

[0046] In some embodiments, R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group, R 5 and R 6 Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group. Preferably, R 1 , R 2 , R 3and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group, R 5 and R 6 Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group. More preferably, R 1 , R 2 , R 3 and R 4 Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, R 5 and R 6 Each of these is independently selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group. More preferably, the base of the structure represented by the general formula (II-1) is [ka] One of the following is selected, where X is a F atom, a Cl atom, or a Br atom.

[0047] In some embodiments, R 1 , R 2 , R 3 and R 4 Each is independent of the others. [ka] X is selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group, and X is an F atom. Preferably, R1 , R 2 , R 3 and R 4 Each is independent of the others. [ka] X is selected from one of the following: a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, and X is a fluorine atom.

[0048] In some embodiments, the cyclic sulfate ester compound is, [ka] Selected from.

[0049] The above-mentioned method for producing cyclic sulfate ester compounds is simple and advantageous for industrial dissemination and implementation. Furthermore, the improvement effect on the battery's cycle characteristics is more stable.

[0050] The compound numbers listed above are shown in the table below. [Table 1-1] [Table 1-2]

[0051] A method for producing a cyclic sulfate ester compound having the structure represented by general formula (I) of this application is described below, referring to the following synthesis route. [ka]

[0052] However, the reaction temperature of the first step may be controlled to 30-60°C, the reaction temperature of the second step to 10-30°C, a catalyst such as ruthenium trichloride trihydrate may be used in the second step to perform catalytic action, and the oxidizing agent may be sodium hypochlorite, ozone, etc. However, R 1 , R2 , R 3 , R 4 n1 and n2 are defined as described above.

[0053] In some embodiments, the mass content of the additive in the non-aqueous electrolyte is 0.001% to 15%, preferably 0.005% to 10%, more preferably 0.05% to 5%, and may be in the range of, for example, 0.001%, 0.003%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 2%, 3%, 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 15%, and any of the above values.

[0054] When the mass content of additives in the non-aqueous electrolyte is within the above range, the high-pressure resistance of the electrolyte is further improved, and the stability and electron-blocking ability of the CEI coating on the positive electrode are further enhanced, thereby suppressing side reactions between the electrolyte and the positive electrode. This improves the battery's DCR, enhances its cycle characteristics and storage performance, and reduces the amount of gas generated during battery cycling.

[0055] In some embodiments, the mass content of the dimethyl carbonate in the non-aqueous solvent is in the range of 5% to 80%, preferably 10% to 70%, more preferably 20% to 50%, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and any of the above values.

[0056] When the mass content of dimethyl carbonate in the non-aqueous solvent is within the above range, the DCR of the battery is further improved, the cycle characteristics and storage performance of the battery are enhanced, the amount of gas generated during battery cycling is reduced, the viscosity of the electrolyte is further reduced, the conductivity of the electrolyte is improved, and consequently the rate characteristics of the battery are enhanced.

[0057] In some embodiments, the electrolyte comprises an electrolyte salt and other solvents.

[0058] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoride arsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bisoxalate borate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0059] In some embodiments, the other solvent may be selected from at least one of methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0060] In some embodiments, the electrolyte selectively further comprises additives. For example, other additives may include negative electrode film forming additives, and may also include additives that can improve specific characteristics of the battery, such as additives that improve the overcharge characteristics of the battery, or additives that improve the high-temperature or low-temperature characteristics of the battery.

[0061] [Positive electrode sheet] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer containing a positive electrode active material.

[0062] Exemplary, the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0063] In some embodiments, the resistance of the positive electrode sheet is 15Ω or less, preferably 8Ω or less, and may be in a range of, for example, 0.5Ω, 1Ω, 2Ω, 3Ω, 4Ω, 5Ω, 6Ω, 8Ω, 9Ω, 10Ω, 11Ω, 12Ω, 13Ω, 14Ω, 15Ω and any of the above values.

[0064] Therefore, this improves the stability and safety of the battery system, while simultaneously providing the battery with good dynamic characteristics, improving the battery's DCR, enhancing the battery's cycle characteristics and storage performance, reducing gas generation during battery cycling, and further improving the battery's rate characteristics.

[0065] In some embodiments, the resistance of the positive electrode sheet is measured using conventional methods in the art. For example, it is measured by the following method.

[0066] The secondary battery is charged with a constant current of 0.33C until it reaches a full charge voltage of 4.3V. Then, it is charged at a constant voltage at the full charge voltage until it reaches a cutoff current of 0.055C to reach a fully charged state. Next, the secondary battery is disassembled, the positive electrode sheet is removed, the positive electrode sheet is held in a 140°C oven for 60 minutes, then cooled to 25°C, sealed, transported, and used for measurement.

[0067] The resistance of the above positive electrode sheet at 25°C was measured using a sheet resistance meter (e.g., BER1200 type). The measurement conditions were a pressure head area of ​​153.94 mm². 2 The pressure was set to 3.5t and the holding time to 50 seconds. Multiple points (e.g., 15 points) on the polarity sheet were measured, with a spacing of 2-3 mm between adjacent measurement points. The resistance values ​​of all measurement points were recorded, and the average value was calculated as the resistance R of the positive electrode sheet.

[0068] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. As the metal foil, for example, aluminum foil can be used. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0069] In some embodiments, the positive electrode active material can be any positive electrode active material for batteries known in the art. Exemplarily, the positive electrode active material may include at least one of olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials usable as positive electrode active materials for batteries may be used. These positive electrode active materials may be used individually or in combination of two or more. Examples of lithium transition metal oxides include lithium cobalt oxide (LiCoO2, etc.), lithium nickel oxide (LiNiO2, etc.), lithium manganese oxide (LiMnO2, LiMn2O4, etc.), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (Also known as), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (Also known as) LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (Also known as), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622 (also called), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM 811 also called), lithium nickel cobalt aluminum oxide (LiNi 0.85 Co 0.15 Al 0.05 O2, etc.) and at least one of its modified compounds may be included, but is not limited thereto. As the olivine-structured lithium-containing phosphate, for example, lithium iron phosphate (e.g., LiFePO4 (also called LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon may be included, but is not limited thereto.

[0070] In some embodiments, the positive electrode active material contains Li 1+x Ni a Co b M 1-a-b O 2-y A y and M contains one or more elements selected from Mn, Fe, Cr, Ti, Zn, V, Al, Zr, Ce, Mg, Ga, Cu, and Nb, preferably contains one or two elements selected from Mn and Al, A contains one or more elements selected from S, F, Cl, and I, preferably contains one or two elements selected from S and F, -0.1 ≦ x ≦ 0.2, 0 < a < 1, preferably 0.5 ≦ a < 1, more preferably 0.7 ≦ a ≦ 0.9, 0 < b < 1, preferably 0 < b < 0.5, more preferably 0 < b ≦ 0.2, 0 < a + b < 1, and 0 ≦ y < 0.2.

[0071] In some embodiments, the positive electrode film layer may selectively further contain a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins.

[0072] In some embodiments, the positive electrode film layer may further selectively contain a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0073] In some embodiments, a positive electrode sheet can be manufactured by the following method: Components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode paste, the positive electrode paste is applied to a positive electrode current collector, and the positive electrode sheet can be obtained through processes such as drying and cold pressing.

[0074] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer containing a negative electrode active material, which is placed on at least one surface of the negative electrode current collector.

[0075] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0076] In some embodiments, the volume-average particle size Dv50 of the negative electrode active material is 3 to 30 μm, preferably 6 to 20 μm, more preferably 8 to 15 μm, and may be in the range of, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 18 μm, 20 μm, 21 μm, 22 μm, 23 μm, 25 μm, 27 μm, 28 μm, 30 μm, and any of the above values.

[0077] Having the volume-average particle size Dv50 of the negative electrode active material within the above range forms a stable SEI film on the negative electrode surface, reduces side reactions between the electrolyte and the negative electrode active material, reduces gas generation during battery cycling, and contributes to improving the battery's cycle characteristics and storage performance. Improving the battery's DCR is advantageous in reducing the degree of polarity of the battery and improving the battery's capacity.

[0078] The volume-average particle size Dv50 represents the particle size corresponding to the point when the cumulative volume distribution percentage of the negative electrode active material reaches 50%. In some embodiments, the volume-average particle size Dv50 is measured using instruments and methods known in the art. For example, it may be measured using a laser particle size analyzer (e.g., MasterSize300), referring to GB / T19077-2016 "Laser Diffraction Method for Particle Size Distribution".

[0079] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0080] In some embodiments, the negative electrode active material can be any negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials for batteries may be used. These negative electrode active materials may be used individually or in combination of two or more types.

[0081] In some embodiments, the negative electrode film layer may selectively further contain a binder. For example, the binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0082] In some embodiments, the negative electrode film layer may further selectively contain a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0083] In some embodiments, the negative electrode film layer further comprises other additives, such as a selective thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0084] In some embodiments, a negative electrode sheet can be manufactured by the following method: Components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode paste, the negative electrode paste is coated onto a negative electrode current collector, and the negative electrode sheet can be obtained through steps such as drying and cold pressing.

[0085] [Separator] In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous structure separator having good chemical and mechanical stability can be selected.

[0086] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. If the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0087] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured into an electrode assembly via a winding process or a lamination process.

[0088] In some embodiments, the secondary battery may include an outer casing. This casing is used to enclose the electrode assembly and electrolyte.

[0089] In some embodiments, the casing material of the secondary battery may be a hard case such as a rigid plastic case, an aluminum case, or a steel case. The casing material of the secondary battery may also be a soft pack such as a pouch-type soft pack. The material of the soft pack may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0090] This application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows a secondary battery 5 with a rectangular structure as an example.

[0091] In some embodiments, referring to Figure 2, the exterior material may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, forming a housing cavity enclosed by the bottom plate and side plates. The housing 51 has an opening that communicates with the housing cavity, and the cover plate 53 can be placed over the opening to seal the housing cavity. The positive electrode sheet, negative electrode sheet, and separator can form an electrode assembly 52 via a winding or lamination process. The electrode assembly 52 is sealed within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select according to specific practical requirements.

[0092] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number can be selected by those skilled in the art depending on the application and capacity of the battery module.

[0093] Figure 3 shows an example of a battery module 4. Referring to Figure 3, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 5 can be fixed in place by fasteners.

[0094] Preferably, the battery module 4 may further include an outer case having a housing space for housing a plurality of secondary batteries 5.

[0095] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which can be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0096] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed inside the battery case. The battery case includes an upper housing 2 and a lower housing 3, the upper housing 2 can be placed over the lower housing 3 and form a sealed space for housing the plurality of battery modules 4. The plurality of battery modules 4 can be arranged inside the battery case in any way.

[0097] Furthermore, the present application provides a power consumption device comprising at least one of a secondary battery, battery module, or battery pack relating to the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device, or as an energy storage element for the power consumption device. The power consumption device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0098] As a power consumption device, a secondary battery, battery module, or battery pack can be selected according to the usage requirements.

[0099] Figure 6 shows an example of a power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements for the secondary battery of the power consumption device, a battery pack or battery module can be used.

[0100] [Examples] Examples of the present application are described below. The examples described below are illustrative and are for interpretive purposes only, and should not be considered as limitations thereon. Where no specific techniques or conditions are shown in the examples, they should be carried out in accordance with the techniques or conditions described in the literature in the art, or in accordance with the product instructions. Where the manufacturer of the reagents or equipment used is not specified, they are all common commercially available products, and information on other reagents or compounds is given in Table 1.

[0101] [Table 2]

[0102] Production example 1: Compound 1 [ka] synthesis Step 1: Add 300 g (2 mol) of 1,6-dideoxyhexitol solid to a 2 L three-necked flask and start stirring. Add 523 g (4.4 mol) of thionyl chloride dropwise to the three-necked flask, controlling the temperature to approximately 15°C during the addition process. After the addition is complete, the reaction is kept at 45°C for 4 hours until a large amount of paste-like solid precipitates in the reaction solution. After cooling, 1 L of deionized water is slowly added dropwise, the reaction system is rapidly stirred to disperse, the solid is filtered, and the resulting solid is washed by beating it multiple times with deionized water until the pH becomes neutral. The filtered cake is dried under reduced pressure at 60°C to obtain the intermediate product.

[0103] Step 2: Add 184.2 g (0.8 mol) of intermediate product 1 to a 3 L three-necked flask, add 1000 mL of acetonitrile, add 80 mg of ruthenium trichloride trihydrate catalyst, purge the system with nitrogen gas, cool to 20°C, start stirring, and within 1 hour add 2000 g of 20% sodium hypochlorite aqueous solution dropwise to control the reaction temperature to 10-20°C. After the dropwise addition is complete, stir at 10-20°C for 10 minutes, separate, and quench the organic phase with sodium sulfite aqueous solution until the potassium iodide starch test paper no longer turns blue. Separate again, concentrate the organic layer, and crystallize with acetonitrile to obtain a white powder solid, which is compound 1.

[0104] 1H-NMR, CD3CN, δ ppm 5.42-5.39 (m, 2H), 5.36-5.34 (m, 2H), 1.67-1.65 (d, 6H).

[0105] Production example 2: Compound 2 [ka] synthesis Step 1: Add 356.5 g (2 mol) of 3,4,5,6-octanetetraol solid to a 2 L three-necked flask and start stirring. Add 523 g (4.4 mol) of thionyl chloride dropwise to the three-necked flask, controlling the temperature to approximately 15°C during the addition process. After the addition is complete, the reaction is incubated at 45°C for 4 hours until a large amount of paste-like solid precipitates in the reaction solution. After cooling, 1 L of deionized water is slowly added dropwise, the reaction system is rapidly stirred to disperse the solid, and the obtained solid is filtered and washed by beating it multiple times with deionized water until the pH becomes neutral. The filtered cake is dried under reduced pressure at 60°C to obtain the intermediate product.

[0106] Step 2: Add 216.2 g (0.8 mol) of intermediate product 1 to a 3 L three-necked flask, add 1000 mL of acetonitrile, add 80 mg of ruthenium trichloride trihydrate catalyst, purge the system with nitrogen gas, cool the system to 20°C, start stirring, and within 1 hour add 2000 g of 20% sodium hypochlorite aqueous solution dropwise to control the reaction temperature to 10-20°C. After the dropwise addition is complete, stir for 10 minutes at 10-20°C, separate the liquids, and quench the organic phase with sodium sulfite aqueous solution until the potassium iodide starch test paper no longer turns blue. Separate the liquids again, concentrate the organic layer, and crystallize it with acetonitrile to obtain compound 2.

[0107] Production example 3: Compound 3 [ka] synthesis Step 1: Add 328.4 g (2 mol) of 2,3,4,5-heptanetetraol solid to a 2 L three-necked flask and start stirring. Add 523 g (4.4 mol) of thionyl chloride dropwise to the three-necked flask, controlling the temperature to approximately 15°C during the addition process. After the addition is complete, the reaction is incubated at 45°C for 4 hours, and a large amount of paste-like solid precipitates in the reaction solution. After cooling, 1 L of deionized water is slowly added dropwise, the reaction system is rapidly stirred to disperse, the solid is filtered, and the obtained solid is washed by beating it multiple times with deionized water until the pH becomes neutral. The filtered cake is dried under reduced pressure at 60°C to obtain the intermediate product.

[0108] Step 2: Add 205 g (0.8 mol) of intermediate product 1 to a 23 three-necked flask, add 1000 mL of acetonitrile, and stir until the solid is completely dissolved. Add 80 mg of ruthenium trichloride trihydrate catalyst, purge the system with nitrogen gas, and then cool the system to 20°C. Start stirring and within 1 hour add 2000 g of 20% sodium hypochlorite aqueous solution dropwise to control the reaction temperature to 10-20°C. After the dropwise addition is complete, stir at 10-20°C for 10 minutes, separate the liquids, and quench the organic phase with sodium sulfite aqueous solution until the potassium iodide starch test paper no longer turns blue. Separate the liquids again, concentrate the organic layer, and crystallize it with acetonitrile to obtain compound 1 (163.1 g, yield 82.8%).

[0109] Production example 4: Compound 9 [ka] synthesis [ka] (CAS number: 7460-93-7) was used in place of 1,6-dideoxyhexitol, and the rest of the preparation was the same as in Preparation Example 1. Compound LC-MS: 285.25.

[0110] Production example 5: Compound 11 [ka] synthesis Step 1: Add 392.4 g (2 mol) of 1,2,3,4,5,6-heptanehexaol solid to a 2 L three-necked flask and start stirring. Add 784.5 g (6.6 mol) of thionyl chloride dropwise to the three-necked flask, controlling the temperature to approximately 15°C during the addition process. After the addition is complete, the reaction is incubated at 45°C for 4 hours, causing a large amount of paste-like solid to precipitate in the reaction solution. After cooling, 1 L of deionized water is slowly added dropwise, the reaction system is rapidly stirred to disperse, the solid is filtered, and the resulting solid is washed by beating it multiple times with deionized water until the pH becomes neutral. The filtered cake is dried under reduced pressure at 60°C to obtain the intermediate product.

[0111] Step 2: Add 140 g (0.4 mol) of intermediate product 1 to a 4 L three-necked flask, add 1000 mL of acetonitrile, add 110 mg of ruthenium trichloride trihydrate catalyst, purge the system with nitrogen gas, cool the system to 20°C, start stirring, and within 1 hour add 1500 g of 20% sodium hypochlorite aqueous solution dropwise to control the reaction temperature to 10-20°C. After the dropwise addition is complete, stir for 10 minutes at 10-20°C, separate the liquids, and quench the organic phase with sodium sulfite aqueous solution until the potassium iodide starch test paper no longer turns blue. Separate the liquids again, concentrate the organic layer, and crystallize it with acetonitrile to obtain compound 11.

[0112] Production example 6: Compound 14 [ka] synthesis Step 1: Add 484 g (2 mol) of 1,2,3,4,5,6,7,8-octaneoctaol solid to a 2 L three-necked flask and start stirring. Add 1046 g (8.8 mol) of thionyl chloride dropwise to the three-necked flask, controlling the temperature to approximately 15°C during the addition process. After the addition is complete, the reaction is kept at 45°C for 4 hours until a large amount of paste-like solid precipitates in the reaction solution. After cooling, 1 L of deionized water is slowly added dropwise, the reaction system is rapidly stirred to disperse, the solid is filtered, and the obtained solid is washed by beating it multiple times with deionized water until the pH becomes neutral. The filtered cake is dried under reduced pressure at 60°C to obtain the intermediate product.

[0113] Step 2: Add 183.2 g (0.4 mol) of the intermediate product to a 4 L three-necked flask, add 1000 mL of acetonitrile, add 150 mg of ruthenium trichloride trihydrate catalyst, purge the system with nitrogen gas, cool the system to 20°C, start stirring, and within 1 hour add 2000 g of 20% sodium hypochlorite aqueous solution dropwise to control the reaction temperature to 10-20°C. After the dropwise addition is complete, stir at 10-20°C for 10 minutes, separate the liquids, and quench the organic phase with sodium sulfite aqueous solution until the potassium iodide starch test paper no longer turns blue. Separate the liquids again, concentrate the organic layer, and crystallize it with acetonitrile to obtain compound 14.

[0114] For the manufacturing methods of compounds 4 to 8, 10, and 12 to 13, please refer to the above manufacturing examples and the manufacturing methods of general formula compounds.

[0115] Example 1 (1) Preparation of electrolyte: Dimethyl carbonate, ethylene carbonate, and methyl ethyl carbonate solvents were mixed, with the proportion of dimethyl carbonate to the total mass of the solvent being 40% by mass, and the mass ratio of ethylene carbonate to ethyl methyl carbonate being 3:7. Subsequently, additive compound 1 and electrolyte salt LiPF6 were uniformly dissolved in the solution to obtain the electrolyte. In this electrolyte, the concentration of LiPF6 was 1 mol / L, and the mass content of compound 1 was 2%.

[0116] (2) Preparation of negative electrode sheet: Graphite, the negative electrode active material, carbon black as a conductive additive, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC-Na) as a thickener were dissolved in deionized water in a weight ratio of 90:4:4:2 and uniformly mixed to produce a negative electrode paste. The negative electrode paste was uniformly applied to the copper foil of the negative electrode current collector once or multiple times, and a negative electrode sheet was obtained by drying, cold pressing, and cutting.

[0117] (3) Manufacturing of positive electrode sheet: LiNi 0.8 Co 0.1 Mn 0.1 O2, the conductive additive acetylene black, and the binder polyvinylidene fluoride (PVDF) were dissolved in the solvent N-methyl-2-pyrrolidone (NMP) in a weight ratio of 90:5:5, and thoroughly stirred and mixed to obtain a positive electrode paste. Subsequently, the positive electrode paste was uniformly applied onto the positive electrode current collector, and a positive electrode sheet was obtained by drying, cold pressing, and cutting.

[0118] (4) Separator: A general-purpose polypropylene film is used as the separator.

[0119] (5) Assembly of the secondary battery: The positive electrode sheet, separator, and negative electrode sheet were stacked in order, with the separator positioned between the positive and negative electrode sheets to act as a separator, and then wound up to obtain the electrode assembly. The electrode assembly was placed in the battery housing, dried, and then the electrolyte was injected. After processes such as chemical formation and standing were carried out to obtain the secondary battery.

[0120] Examples 2-30 and Comparative Examples 1-2 are similar to the secondary battery manufacturing method of Example 1, and Table 2 is provided for details of the parameters of the different products. The resistance of the positive electrode sheet is adjusted by the mass ratio of the conductive agent to the positive electrode active material.

[0121] [Table 3-1] [Table 3-2]

[0122] Material testing and battery testing (1) Test of volume-average particle size Dv50: The measurements were taken using a Mastersizer 2000E laser particle size analyzer manufactured by Malvern Instruments, UK, in accordance with GB / T 19077-2016 "Particle Size Distribution Laser Diffraction Method".

[0123] (2) Measurement of the resistance of the positive electrode sheet: The secondary battery is charged with a constant current of 0.33C until it reaches a full charge voltage of 4.3V. Then, it is charged at a constant voltage at the full charge voltage until it reaches a cutoff current of 0.055C to reach a fully charged state. Next, the secondary battery is disassembled, the positive electrode sheet is removed, the positive electrode sheet is held in a 140°C oven for 60 minutes, then cooled to 25°C, sealed, transported, and used for measurement.

[0124] The resistance of the above positive electrode sheet at 25°C was measured using a BER1200 type sheet resistance meter. The measurement conditions were a pressure head area of ​​153.94 mm². 2 The pressure was set to 3.5t and the holding time to 50 seconds. Measurements were taken at 15 points on the polarity sheet, with a spacing of 2-3mm between adjacent measurement points. The resistance values ​​of all measurement points were recorded, and the average value was calculated as the resistance R of the positive electrode sheet.

[0125] (3) DCR measurement: Under room temperature conditions, the secondary battery was charged to 4.3V with a constant current of 1C, then charged at a constant voltage of 4.3V until the current reached 0.05C. After standing for 5 minutes, it was discharged at 1C for 30 minutes (at this point, the cell's remaining capacity was 50% SOC). It was then left to stand for another 5 minutes. The temperature was adjusted to 25°C, and it was left to stand for 1 hour, during which the cell voltage V1 was recorded. Next, it was discharged at 4C for 30 seconds, and the voltage V2 after pulse discharge was recorded. The DCR of the cell at 50% SOC after 30 seconds of discharge is calculated using the following formula.

[0126] At 50% SOC, the DCR during a 30-second discharge is (V1-V2) / I, where I=4C.

[0127] (4) Testing of cycle characteristics: Four secondary batteries were taken from each group of examples and comparative examples, and the discharge capacity retention rate of the secondary batteries was calculated by repeatedly charging and discharging them according to the procedure below, and the average value was taken.

[0128] Under conditions of 45°C, the secondary battery was first completely discharged at 1C before being tested. The test process was as follows: Under conditions of 45°C, the secondary battery was charged with a constant current of 1C until the voltage reached 4.3V, and then charging was continued at a constant voltage of 4.3V until the current reached 0.05C. After standing for 5 minutes, the secondary battery was discharged with a constant current of 0.5C until the voltage reached 3.0V. This constituted one charge-discharge cycle, and the discharge capacity was recorded as the discharge capacity of the first cycle. Subsequently, charging and discharging were repeated, and the discharge capacity after 400 cycles was calculated. The capacity retention rate after 400 cycles was calculated according to the following formula.

[0129] 400-cycle capacity retention rate (%) = (Discharge capacity at the 400th cycle / Discharge capacity at the first cycle) × 100%.

[0130] (5) Testing of storage performance: At 25°C, the secondary battery was first charged to 4.3V with a constant current of 0.5C, then charged at a constant voltage of 4.3V with a cutoff current of 0.05C. Next, it was discharged to 3.0V with a constant current of 0.5C, and the discharged capacity was recorded as the initial capacity C0. Subsequently, the secondary battery was charged to 4.3V with a constant current of 0.5C, and then charged at a constant voltage of 4.3V with a cutoff current of 0.05C. After that, the secondary battery was stored in a constant temperature bath at 60°C for 15 days. After storage was complete, the battery was removed and discharged again to 3.0V with a constant current of 0.5C, and the discharged capacity C1 after storage was recorded. Subsequently, the capacity retention rate after 15 days of storage at a constant temperature of 60°C was calculated using the following formula.

[0131] The volume retention rate after 15 days of storage at a constant temperature of 60°C is 100% × C1 / C0.

[0132] (6) Gas emission test during cycling at 45°C: The test was conducted after completely discharging the secondary battery at 1C under conditions of 45°C. The test process was as follows: Under conditions of 45°C, the secondary battery was charged with a constant current of 1C until the voltage reached 4.3V, and then charging was continued at a constant voltage of 4.3V until the current reached 0.05C. After standing for 5 minutes, the lithium-ion battery was discharged with a constant current of 0.5C until the voltage reached 3.0V. This constituted one charge-discharge cycle, and the discharge capacity was recorded as the discharge capacity of the first cycle. Subsequently, the charge and discharge cycle was performed, repeating a total of 400 times. The volume V1 of the battery before the high-temperature cycle was measured using the water displacement method, and after the cycle was completed, the battery was removed and cooled for 8 hours, and then the volume V2 of the battery after the cycle was measured. The volume expansion rate of the battery after 400 cycles was calculated using the following formula.

[0133] The volume expansion rate of the battery after 400 cycles = (V2 / V1-1) × 100%.

[0134] The results of (1) to (2) above are shown in Table 1, and the results of (3) to (6) are shown in Table 3.

[0135] [Table 4]

[0136] The following points were revealed from the results described above.

[0137] Compared to Comparative Example 1, the batteries of Examples 1-10 of the present application show improved DCR, superior cycle characteristics, and less gas generation during cycling. Compared to Comparative Example 2, the batteries of Examples 11-13 of the present application show improved DCR, superior cycle characteristics, higher storage performance, and less gas generation during cycling. The batteries using the non-aqueous electrolyte of the present application have been shown to show improved DCR, improved cycle characteristics and storage performance, and less gas generation during cycling.

[0138] Compared to Comparative Example 23, the batteries of Examples 1, 15-16 of the present invention exhibit improved DCR, superior cycle characteristics, higher storage performance, and lower gas generation during cycling.

[0139] Compared to Comparative Examples 25-26, the batteries of Examples 1 and 17-18 of the present application exhibit superior cycle characteristics and less gas generation during cycling. Furthermore, the batteries of Examples 1 and 17-18 of the present application have superior DCR performance compared to the battery of Example 25.

[0140] Compared to Comparative Example 27, the batteries of Examples 1 and 19-20 of the present application exhibit improved DCR, superior cycle characteristics, higher storage performance, and lower gas generation during cycling.

[0141] Compared to Comparative Example 28, the batteries of Examples 1 and 21-22 of the present application exhibit superior cycle characteristics, higher storage performance, and lower gas generation during cycling. Compared to Example 29, the batteries of Examples 1 and 21-22 of the present application show improved DCR. Compared to Comparative Example 30, the battery of Example 1 of the present application shows improved DCR, superior cycle characteristics, higher storage performance, and lower gas generation during cycling.

[0142] Furthermore, this application is not limited to the embodiments described above. The embodiments described above are merely examples, and any embodiment that has substantially the same configuration as the technical idea and produces the same effects within the scope of the technical solutions of this application is included within the scope of this application. In addition, any modifications that can be conceived by a person skilled in the art, without departing from the spirit of this application, or other forms constructed by combining some of the components of the embodiments, are also included within the scope of this application.

Claims

1. A non-aqueous electrolyte for a secondary battery comprising an additive and a non-aqueous solvent containing dimethyl carbonate, The aforementioned additive includes a cyclic sulfate ester compound represented by formula (I), 【Chemistry 1】 However, R １ , R ２ , R ３ and R ４ Each of the following is independently selected from a group having the structure shown in formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, and n1 and n2 are independently any integer from 0 to 2. 【Chemistry 2】 R ５ and R ６ Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, and n3 is any integer from 0 to 2. R １ and R ２ are not hydrogen atoms at the same time and R ３ and R ４ are not hydrogen atoms at the same time, Or, R １ , R ２ , R ３ , R ４ , R ５ and R ６ teeth, R １ and R ２ It is simultaneously a hydrogen atom and R ３ and R ４ One of them is a hydrogen atom, and the other is one of the following: a group having the structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, and in the group having the structure represented by general formula (II), R ５ and R ６ It also satisfies the condition that it is not a hydrogen atom, Or, R １ , R ２ , R ３ , R ４ , R ５ and R ６ teeth, R ３ and R ４ It is also a hydrogen atom, R １ and R ２ One of the atoms is a hydrogen atom, and the other is any one of the following: a group having the structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group, and R in the group having the structure represented by general formula (II). ５ and R ６ A non-aqueous electrolyte for secondary batteries that satisfies the condition that it is not a hydrogen atom at the same time.

2. The cyclic sulfate ester compound has the structure shown in formula (I-1), 【Transformation 3】 R １ , R ２ , R ３ and R ４ Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group. 【Chemistry 4】 R ５ and R ６ The non-aqueous electrolyte for a secondary battery according to claim 1, wherein each of the following is independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group.

3. R １ , R ２ , R ３ and R ４ Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group, R ５ and R ６ Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, and a cyano group. Preferably, R １ , R ２ , R ３ and R ４ Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group, R ５ and R ６ Each of these is independently selected from one of the following: a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, and a cyano group. More preferably, R １ , R ２ , R ３ and R ４ Each of these is independently selected from one of the following: a group having the structure represented by general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, R ５ and R ６ Each of these is independently selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group. More preferably, the base of the structure represented by the general formula (II-1) is 【Transformation 5】 A non-aqueous electrolyte for a secondary battery according to claim 2, wherein one of the following is selected, where X is an F atom, a Cl atom, or a Br atom.

4. R １ , R ２ , R ３ and R ４ Each is independent of the others. 【Transformation 6】 X is selected from one of the following: hydrogen atom, F atom, Cl atom, Br atom, methyl group, ethyl group, propyl group, isopropyl group, trifluoromethyl group, ethoxy group, and cyano group, and X is an F atom. Preferably, R １ , R ２ , R ３ and R ４ Each is independent of the others. 【Transformation 7】 A non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 3, wherein X is selected from one of a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group, and a cyano group, and X is a fluorine atom.

5. The aforementioned cyclic sulfate ester compound is a compound of 【Transformation 8】 A non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 4, selected from the above.

6. The non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 5, wherein the mass content of the additive in the non-aqueous electrolyte is 0.001% to 15%, preferably 0.005% to 10%, and more preferably 0.05% to 5%.

7. The non-aqueous electrolyte according to any one of claims 1 to 6, wherein the mass content of the dimethyl carbonate in the non-aqueous solvent is 5% to 80%, preferably 10% to 70%, and more preferably 20% to 50%.

8. It is a secondary battery, A secondary battery comprising a non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 7, a positive electrode sheet, and a negative electrode sheet containing a negative electrode active material, wherein the secondary battery is a lithium secondary battery.

9. The secondary battery according to claim 8, wherein the resistance of the positive electrode sheet is 15 Ω or less, preferably 8 Ω or less.

10. The secondary battery according to claim 8 or 9, wherein the volume average particle size Dv50 of the negative electrode active material is 3 to 30 μm, preferably 6 to 20 μm, and more preferably 8 to 15 μm.

11. The positive electrode sheet contains a positive electrode active material, Preferably, the positive electrode active material is Li １＋ｘ Ni ａ Co ｂ M １－ａ－ｂ O ２－ｙ A ｙ A secondary battery according to any one of claims 8 to 10, wherein M comprises one or more elements from Mn, Fe, Cr, Ti, Zn, V, Al, Zr, Ce, Mg, Ga, Cu, and Nb, preferably one or two elements from Mn and Al, A comprises one or more elements from S, F, Cl, and I, preferably one or two elements from S and F, -0.1 ≤ x ≤ 0.2, 0 < a < 1, preferably 0.5 ≤ a < 1, more preferably 0.7 ≤ a ≤ 0.9, 0 < b < 1, preferably 0 < b < 0.5, more preferably 0 < b ≤ 0.2, 0 < a + b < 1, and 0 ≤ y < 0.

2.

12. A power consumption device comprising a non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 7, or a secondary battery according to any one of claims 8 to 11.

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