Lithium-ion secondary battery and electric apparatus

Abstract

A lithium-ion secondary battery and an electric apparatus. Parameters related to a negative electrode and an electrolyte of a lithium-ion secondary battery are rationally designed, such that the lithium-ion secondary battery satisfies 6.7≤CB×PD / (η×A)≤160 (CB representing a capacity excess coefficient of the lithium-ion secondary battery; A representing the mass percentage content of ethylene sulfate in the electrolyte; PD representing the compaction density of a negative electrode active material layer; and η representing the viscosity of the electrolyte).

Description

Lithium ion secondary battery and power-consuming device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese invention patent application CN202310791633.8 filed on June 29, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a lithium-ion secondary battery and an electrical device. Background Art

[0004] Lithium secondary batteries, with their outstanding features such as high specific energy, long life, environmental friendliness, and lack of memory effect, are widely used in portable electronic devices and new energy vehicles. However, limited range limits the rapid adoption of new energy vehicles. Improving the range of new energy vehicles can be achieved by shortening the battery's charging time. Therefore, providing a lithium-ion secondary battery that can be quickly charged is a pressing issue.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a lithium-ion secondary battery with excellent fast-charging performance. This application can significantly improve the fast-charging performance and cycle performance of the lithium-ion secondary battery by rationally designing the relevant parameters of the negative electrode and electrolyte of the lithium-ion secondary battery.

[0007] To achieve the above objectives, in a first aspect, the present application provides a lithium-ion secondary battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; the electrolyte comprises an organic solvent, a lithium salt, and an additive, wherein the additive comprises vinyl sulfate;

[0008] The lithium-ion secondary battery satisfies the following relationship: 6.7≤CB×PD / (η×A)≤160,

[0009] Wherein, CB represents the excess capacity coefficient of lithium-ion secondary batteries, which is the ratio of the negative electrode capacity to the positive electrode capacity under the same area;

[0010] A represents the mass percentage of vinyl sulfate in the electrolyte;

[0011] PD g / cm 3 Indicates the compaction density of the negative electrode active material layer;

[0012] ηmPa·s represents the viscosity of the electrolyte at 25°C.

[0013] In some embodiments, the lithium ion secondary battery satisfies the following relationship: 14≤CB×PD / (η×A)≤62.

[0014] In some embodiments, the lithium-ion secondary battery has an excess capacity factor CB of 1 to 1.6.

[0015] In some embodiments, the mass percentage A of vinyl sulfate in the electrolyte is 0.5% to 3%.

[0016] In some embodiments, the compaction density of the negative electrode active material layer is PD g / cm 3 1~2g / cm 3 .

[0017] In some embodiments, the electrolyte has a viscosity η mPa·s at 25° C. of 2 to 5 mPa·s.

[0018] In some embodiments, in the negative electrode active material layer, the negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.

[0019] In some embodiments, in the negative electrode active material layer, the D V50 5~30μm, D V50 It is the particle size corresponding to when the cumulative volume percentage of the negative electrode active material reaches 50%.

[0020] In some embodiments, in the negative electrode active material layer, the oil absorption value (DBP value) of the negative electrode active material is 10 to 100 mL / 100 g.

[0021] In some embodiments, the total mass m of the electrolyte inside the lithium-ion secondary battery and the rated capacity cap of the battery satisfy the following relationship: m / cap=1.5-5 g / Ah.

[0022] In some embodiments, in the electrolyte, the organic solvent includes at least one of cyclic carbonate, chain carbonate, and carboxylic acid ester.

[0023] In some embodiments, in the electrolyte, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, and lithium tetrafluoroborate.

[0024] In some embodiments, the electrolyte solution includes an additive further comprising at least one of vinylene carbonate, 1,3-propane sultone, fluoroethylene carbonate, tris(trimethylsilyl)phosphate, and lithium difluorophosphate.

[0025] In a second aspect of the present application, an electrical device is provided, wherein the electrical device includes the above-mentioned lithium-ion secondary battery.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present application rationally designs the relevant parameters of the negative electrode and electrolyte of the lithium-ion secondary battery. Specifically, by controlling the battery's capacity excess coefficient, the negative electrode compaction density and the electrolyte-related parameters and combining them through a specific relationship, the calculated value of the relationship is satisfied within a specific range. This can avoid battery polarization or poor ion diffusion caused by thick electrode plates during fast charging, which ultimately affects the battery's cycle, fast charging and kinetic performance, and significantly improve the fast charging performance of the lithium-ion secondary battery. DETAILED DESCRIPTION

[0028] To better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the art. Unless otherwise specified, the reagents and materials used in the present application are commercially available.

[0029] An embodiment of the present application provides a lithium-ion secondary battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; the electrolyte comprises an organic solvent, a lithium salt, and an additive; the additive comprises vinyl sulfate; and the lithium-ion secondary battery satisfies the following relationship: 6.7≤CB×PD / (η×A)≤160,

[0030] Wherein, CB represents the excess capacity coefficient of lithium-ion secondary batteries, which is the ratio of the negative electrode capacity to the positive electrode capacity under the same area;

[0031] A represents the mass percentage of vinyl sulfate in the electrolyte;

[0032] PD g / cm 3 Indicates the compaction density of the negative electrode active material layer;

[0033] ηmPa·s represents the viscosity of the electrolyte at 25°C.

[0034] During the charging process of a lithium-ion secondary battery, lithium ions are released from the positive electrode, accompanied by liquid-phase diffusion of the electrolyte in the negative porous electrode, and charge exchange occurs on the surface of the negative electrode active material. Subsequently, the lithium ions undergo solid-phase conduction within the negative electrode active material particles. Therefore, the negative electrode and electrolyte play an important role in improving the fast-charging performance of lithium-ion secondary batteries.

[0035] Through extensive research, the inventors of this application have discovered that by controlling the viscosity of the electrolyte, the mass percentage of vinyl sulfate (DTD) in the electrolyte, the capacity excess coefficient of the battery design, and the compaction density of the negative electrode, so that the relationship between the above parameters meets a specific range, it is possible to avoid battery polarization or poor ion diffusion caused by thick electrode plates during fast charging, which ultimately affects the battery's cycle, fast charging, and kinetic performance, significantly improve the fast charging performance of lithium-ion secondary batteries, and greatly shorten the battery charging time.

[0036] In some embodiments of the present application, the value of CB×PD / (η×A) can be any value among 6.7, 7, 9, 10, 12, 14, 20, 25, 30, 35, 40, 45, 50, 55, 62, 70, 75, 80, 90, 100, 123, 140, 148, 152, and 160, or it can be an interval range formed by any two of the above values, such as 10-123, 20-55, 30-50, 35-45, etc.

[0037] In some embodiments of the present application, when the lithium-ion secondary battery satisfies 14≤CB×PD / (η×A)≤62, the lithium-ion secondary battery has better fast charging performance and also has a longer cycle life.

[0038] In some embodiments of the present application, the capacity excess coefficient (CB) of the lithium-ion secondary battery is selected to be within the range of 1 to 1.6. During charging and discharging, the active ions of the positive electrode are released and embedded in the negative electrode. The capacity excess coefficient represents the relationship between the capacity that the negative electrode can accept and the capacity released by the positive electrode. When the CB value is within this range, the content of the negative electrode active material is moderate and is not easily reduced and precipitated on the negative electrode surface, resulting in capacity decay and thus a decrease in the battery's cycle performance. In addition, the lithium ions have good liquid-phase conductivity in the negative electrode, which is beneficial to the rapid charging performance of the lithium-ion secondary battery.

[0039] The excess capacity factor (CB) of a lithium-ion secondary battery is the ratio of the negative electrode capacity to the positive electrode capacity at the same area. Its value can be measured using existing technical methods. For example, the positive and negative electrode capacities can be measured by assembling button cells with positive and negative electrode sheets of the same area and lithium sheets, respectively, and then measuring the charge capacity using a blue battery tester. In some embodiments of the present application, the excess capacity factor (CB) of the lithium-ion secondary battery can be 1.0, 1.1, 1.15, 1.2, 1.24, 1.3, or 1.6, or can be an interval formed by any two of the above values, such as 1.1-1.5, 1.05-1.4, or 1.1-1.4.

[0040] In some embodiments of the present application, the compaction density of the negative electrode active material layer is PD g / cm 31~2g / cm 3 The appropriate compaction density of the negative electrode active material layer can fully infiltrate the electrolyte, which is conducive to the charge exchange of lithium ions on the surface of the negative electrode active material and the liquid phase conduction inside the pores of the negative electrode sheet, thereby improving the charging speed of the battery.

[0041] In this application, the compaction density of the negative electrode active material layer is PD g / cm 3 It can be obtained by the following method: the weighing area is a cm 2 The negative electrode sheet is weighed and its mass is recorded as M g. Then the negative electrode current collector of the same area is weighed and its mass is recorded as mg. The thickness of the negative electrode sheet is measured as D cm and the thickness of the negative electrode current collector is d cm. The compacted density of the negative electrode active material layer is calculated according to PD = (Mm) / [a × (Dd)]. In some embodiments of the present application, PD g / cm 3 The specific choice can be 1.0g / cm 3 , 1.1g / cm 3 , 1.2g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 , 2.0g / cm 3 , or it can be the interval formed by any two of the above values, such as 1.3 to 1.9 g / cm 3 , 1.2~1.8g / cm 3 , 1.4~1.8g / cm 3 1.5~1.8g / cm 3 etc.

[0042] In some embodiments of the present application, the viscosity of the electrolyte at 25°C, ηmPa·s, is in the range of 2 to 5mPa·s. An electrolyte with an appropriate viscosity can ensure that the electrolyte has a certain degree of oxidation resistance and is not easily decomposed at high temperatures, resulting in flatulence. At the same time, an appropriate viscosity can ensure that the electrolyte has good wettability, improving the fast charging performance of the battery. In addition, an appropriate viscosity can further reduce the heat generated during the battery's charge and discharge cycles, thereby increasing the battery's cycle life. It is understood that the viscosity of the electrolyte can be controlled by adjusting the composition of the electrolyte.

[0043] In the present application, the viscosity of the electrolyte can be measured using an 1835 Ubbelohde viscometer. In some embodiments of the present application, the specific selection of the viscosity ηmPa·s of the electrolyte can be 2mPa·s, 3.1mPa·s, 3.2mPa·s, 4mPa·s, 4.1mPa·s, 4.2mPa·s, 4.3mPa·s, 4.4mPa·s, 4.5mPa·s, 4.7mPa·s, 5mPa·s, or an interval range formed by any two of the above values, for example, 2-4mPa·s, 2-4.5mPa·s, 4-4.5mPa·s, etc.

[0044] In some embodiments of the present application, the weight percentage of vinyl sulfate in the electrolyte is 0.5% to 3%. For example, the weight percentage of vinyl sulfate in the electrolyte can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or a range consisting of any two of the above values. Within this range of vinyl sulfate content, the cycling performance can be improved while ensuring fast charging performance.

[0045] In this application, the vinyl sulfate content is measured using gas chromatography: using dimethyl carbonate as the solvent, a series of standard vinyl sulfate solutions of varying concentrations are prepared. The gas chromatograph measures the concentrations from low to high, integrating the peak areas. The peak areas correspond to the vinyl sulfate content, and a calibration curve is plotted based on the relationship between peak areas and vinyl sulfate concentration. When measuring vinyl sulfate in the electrolyte, the peak areas are compared with the peak areas in the calibration curve to determine the vinyl sulfate content.

[0046] The excess capacity coefficient CB of the lithium-ion secondary battery, the compaction density PD of the negative electrode active material layer, the viscosity η of the electrolyte, and the mass percentage A of vinyl sulfate in the electrolyte jointly affect the fast charging and cycle performance of the lithium-ion battery.

[0047] Therefore, in order to meet the requirements of fast charging and battery service life, the capacity excess coefficient CB of the lithium-ion secondary battery, the compaction density PD of the negative electrode active material layer, the viscosity η of the electrolyte, and the mass percentage A of vinyl sulfate in the electrolyte are controlled to meet the range described in the relationship 6.7≤CB×PD / (η×A)≤160, which can ensure the cycle performance while meeting the requirements of fast charging.

[0048] In some embodiments of the present application, the negative electrode active material in the negative electrode active material layer includes at least one of graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.

[0049] In some embodiments of the present application, the particle size D of the negative electrode active material is V50 5 to 30 μm. In this application, the particle size D of the negative electrode active materialV50 The value of is in this range, which is conducive to the rapid diffusion of lithium ions in the negative electrode active material. V50 It is the particle size corresponding to when the cumulative volume percentage of the negative electrode active material reaches 50%.

[0050] In some embodiments of the present application, the oil absorption value (DBP value) of the negative electrode active material is 10 to 100 mL / 100 g. The oil absorption value of the negative electrode active material is within this range, which is beneficial to reducing the contact impedance between the material and the electrolyte and further improving the kinetic performance.

[0051] In this application, the oil absorption value (DBP value) of the negative electrode active material can be measured by the following method: add the weighed negative electrode active material to the mixing chamber of the oil absorptometer and close the lid; align the oil delivery pipe of the constant-rate burette with the hole above the mixing chamber lid, set the constant-rate burette counter to zero, and ensure that there are no bubbles in the burette delivery pipe; start the oil absorptometer, start the instrument, and drip oil (DBP (dibutyl phthalate) solvent); when the dripping oil causes the semi-plastic agglomerates to reach a preset torque level, the oil absorptometer and constant-rate burette are simultaneously closed. The oil absorption value of the negative electrode active material is then the ratio of the dripping volume of DBP to the mass of the weighed negative electrode active material. In some embodiments of the present application, the oil absorption value (DBP value) of the negative electrode active material can be specifically 10mL / 100g, 20mL / 100g, 30mL / 100g, 40mL / 100g, 50mL / 100g, 60mL / 100g, 70mL / 100g, 80mL / 100g, 90mL / 100g, 100mL / 100g, or it can be an interval range formed by any two of the above values, for example, 20-90mL / 100g, 30-80mL / 100g, 40-70mL / 100g, 50-60mL / 100g, etc.

[0052] In some embodiments of the present application, the positive electrode active material on the positive electrode plate includes at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, nickel cobalt aluminum manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide, lithium rich manganese based solid solution or lithium manganese oxide.

[0053] In some embodiments of the present application, the ratio (m / cap) of the total mass (m) of the electrolyte within the lithium-ion secondary battery to the rated capacity (cap) of the battery is 1.5 to 5 g / Ah. A ratio of m / cap within this range enhances electrolyte wetting of the electrode plates, providing a pathway for lithium ion migration and improving kinetic performance.

[0054] In some embodiments of the present application, the ratio m / cap of the total mass m of the electrolyte inside the lithium-ion secondary battery to the rated capacity cap of the battery can be specifically 1.5g / Ah, 2g / Ah, 2.5g / Ah, 3g / Ah, 3.5g / Ah, 4g / Ah, 4.5g / Ah, 5g / Ah, or an interval range formed by any two of the above values, for example, within the range of 1.5-4g / Ah, 2-5g / Ah, 3-5g / Ah, etc.

[0055] In some embodiments of the present application, the organic solvent includes at least one of a cyclic carbonate, a chain carbonate, and a carboxylic acid ester. The cyclic carbonate includes at least one of ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone; the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methylpropyl carbonate; and the carboxylic acid ester includes at least one of ethyl acetate, propyl propionate, ethyl butyrate, ethyl propionate, and propyl butyrate.

[0056] In some embodiments of the present application, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, and lithium tetrafluoroborate.

[0057] In some embodiments of the present application, the lithium salt includes lithium hexafluorophosphate and at least one of lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, and lithium tetrafluoroborate. When the electrolyte contains these lithium salts, lithium ion transfer can be ensured, further improving kinetic performance during high-rate fast charging.

[0058] In some embodiments of the present application, the lithium salt includes lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0059] In some embodiments of the present application, in addition to vinyl sulfate (i.e., the first additive), the electrolyte may further include a second additive comprising tris(trimethylsilyl) phosphate (TMSP) and at least one of vinylene carbonate (VC), 1,3-propane sultone (PS), fluoroethylene carbonate (FEC), and lithium difluorophosphate (LiDFP). Including the second additive in the electrolyte can further improve kinetic performance.

[0060] In some embodiments of the present application, based on the total mass of the electrolyte, the content of the second additive is 0.1% to 5%.

[0061] In some embodiments of the present application, the second additive comprises tris(trimethylsilyl)phosphate (TMSP).

[0062] In some embodiments of the present application, based on the total mass of the electrolyte, the mass percentage of the second additive is 0.1% to 1%.

[0063] In some embodiments of the present application, the ratio of the mass percentage of vinyl sulfate to the mass percentage of tris(trimethylsilyl)phosphate in the electrolyte is 0.05 to 0.5.

[0064] In some embodiments of the present application, the type of the separator is not particularly limited and may be any separator material used in existing batteries, such as polyethylene, polypropylene, polyvinylidene fluoride, or multilayer composite films thereof.

[0065] An embodiment of the present application also provides an electrical device comprising the lithium-ion secondary battery.

[0066] The following are specific examples of the present application, and the technical solutions of the present application are further described in conjunction with the examples, but the present application is not limited to these examples. The reagents, methods and equipment used in this application, unless otherwise specified, are conventional reagents, methods and equipment in the art.

[0067] Example 1

[0068] Example 1 provides a lithium-ion secondary battery with a rated capacity of 120 Ah, the preparation method of which comprises the following steps:

[0069] Positive electrode preparation

[0070] The positive electrode active material (NCM613), conductive agent (acetylene black) and binder (polyvinylidene fluoride) were mixed in a mass ratio of 96:2:2, NMP solvent was added, and the mixture was dispersed and mixed under vacuum stirring to a uniform slurry system. The slurry was coated on the positive electrode collector (aluminum foil), dried in an oven, cold pressed and cut to obtain positive electrode sheets.

[0071] Negative electrode preparation

[0072] The negative electrode active material (graphite, D V50 The conductive agent (acetylene black), the thickener (sodium carboxymethyl cellulose) and the binder (styrene-butadiene rubber) are mixed in a mass ratio of 96.2:1:1.4:1.4, and an appropriate amount of deionized water is added and the mixture is fully stirred under vacuum to obtain a negative electrode slurry. The slurry is coated on a negative electrode collector (copper foil), dried in an oven, and then cold pressed and cut to obtain a negative electrode sheet.

[0073] Electrolyte preparation

[0074] Under an argon atmosphere, ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed in a mass ratio of 3:5:2 to form a mixed solvent. Thoroughly dried lithium hexafluorophosphate was then added to the mixed solvent, followed by the addition of vinyl sulfate, and the mixture was stirred to form an electrolyte. The electrolyte contained 12.5% ​​lithium hexafluorophosphate by mass, 2% vinyl sulfate, and had a viscosity of 4 mPa·s.

[0075] Lithium-ion secondary battery assembly

[0076] The positive electrode sheet, isolation film (polyethylene film), and negative electrode sheet prepared above are stacked in order, so that the isolation film is placed between the positive and negative electrode sheets to play an isolating role, and then wound to obtain a bare battery cell; the bare battery cell is placed in an outer packaging shell, baked and dried, and then 360g of electrolyte is injected. After vacuum packaging, standing, formation, shaping and other processes, a lithium-ion secondary battery is obtained.

[0077] Examples 2 to 29 and Comparative Examples 1 to 2

[0078] The lithium ion secondary batteries of Examples 2 to 29 and Comparative Examples 1 to 2 were prepared by referring to the method of Example 1. The differences are shown in Table 1.

[0079] Examples 30 to 33

[0080] The difference between Examples 30 to 33 and Example 1 is that the mass of the injected electrolyte is different, as shown in Table 1.

[0081] Examples 34 to 38

[0082] The difference between Examples 34 to 38 and Example 1 is that the additive in the electrolyte further includes tris(trimethylsilyl)phosphate (TMSP). The amount of tris(trimethylsilyl)phosphate added is shown in Table 2.

[0083] The fast charging performance and long cycle performance of the lithium ion secondary batteries prepared in the above examples and comparative examples were tested. The specific testing steps are as follows:

[0084] 1. Fast charging performance: At 25°C, the lithium-ion batteries prepared in the examples and comparative examples were fully charged to 4.4V at 4C and fully discharged to 2.8V at 1C. After repeating this 10 times, the lithium-ion batteries were fully charged to 4.4V at 4C. The negative electrode plates were then disassembled and the lithium deposition on the surface of the negative electrode plates was observed. Among them, if the area of ​​lithium deposition on the negative electrode surface is less than 5%, it is considered to be mild lithium deposition, if the area of ​​lithium deposition on the negative electrode surface is 5% to 40%, it is considered to be moderate lithium deposition, and if the area of ​​lithium deposition on the negative electrode surface is greater than 40%, it is considered to be severe lithium deposition.

[0085] 2. Cycle performance: At 25°C, the lithium-ion batteries prepared in the examples and comparative examples were charged at an equivalent rate of 3C and discharged at a rate of 1C, and a full charge and discharge (2.8-4.4V) cycle test was performed until the capacity of the lithium-ion battery decayed to 80% of the initial capacity. The number of cycles at this time was recorded.

[0086] Table 1 Parameters and performance test results of Examples 1 to 33 and Comparative Examples 1 to 2

[0087] Table 2 Parameters and performance test results of Examples 34 to 38

[0088] The results of the above examples further demonstrate that when a lithium-ion secondary battery satisfies the relationship 6.7 ≤ CB × PD / (η × A) ≤ 160, it achieves both fast charging and long cycle life. Furthermore, Examples 34 to 38 demonstrate that adding an appropriate amount of tris(trimethylsilyl)phosphate can further improve cycle performance.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A lithium-ion secondary battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, wherein: The negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; the electrolyte comprises an organic solvent, a lithium salt and an additive; the additive comprises vinyl sulfate; The lithium-ion secondary battery satisfies the following relationship: 6.7≤CB×PD / (η×A)≤160, Wherein, CB represents the excess capacity coefficient of lithium-ion secondary batteries, which is the ratio of the negative electrode capacity to the positive electrode capacity under the same area; A represents the mass percentage of vinyl sulfate in the electrolyte; PD g / cm 3 Indicates the compaction density of the negative electrode active material layer; ηmPa·s represents the viscosity of the electrolyte at 25°C.

2. The lithium ion secondary battery according to claim 1, wherein The lithium ion secondary battery satisfies the following relationship: 14≤CB×PD / (η×A)≤62.

3. The lithium ion secondary battery according to claim 1, wherein The excess capacity factor CB of the lithium ion secondary battery is 1 to 1.

6.

4. The lithium ion secondary battery according to claim 1, wherein The mass percentage A of vinyl sulfate in the electrolyte is 0.5% to 3%.

5. The lithium ion secondary battery according to claim 1, wherein The compaction density of the negative electrode active material layer is PD g / cm 3 1~2g / cm 3 .

6. The lithium ion secondary battery according to claim 1, wherein The viscosity ηmPa·s of the electrolyte at 25° C. is 2 to 5 mPa·s.

7. The lithium ion secondary battery according to any one of claims 1 to 6, wherein: In the negative electrode active material layer, the negative electrode active material satisfies at least one of the following conditions: (1) The negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate; (2) D of the negative electrode active material V50 5~30μm, D V50 It is the particle size corresponding to when the cumulative volume percentage of the negative electrode active material reaches 50%; (3) The oil absorption value of the negative electrode active material is 10 to 100 mL / 100 g.

8. The lithium ion secondary battery according to any one of claims 1 to 6, wherein: The total mass m of the electrolyte of the lithium ion secondary battery and the rated capacity cap of the lithium ion secondary battery satisfy: m / cap=1.5-5g / Ah.

9. The lithium ion secondary battery according to any one of claims 1 to 6, wherein: The electrolyte satisfies at least one of the following conditions: (1) The organic solvent includes at least one of cyclic carbonate, chain carbonate, and carboxylic acid ester; (2) The lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, and lithium tetrafluoroborate; (3) The additive further includes at least one of vinylene carbonate, 1,3-propane sultone, fluoroethylene carbonate, tris(trimethylsilyl)phosphate, and lithium difluorophosphate.

10. The lithium ion secondary battery according to claim 9, wherein The additives also include tris(trimethylsilyl)phosphate.

11. The lithium ion secondary battery according to any one of claims 1 to 6, wherein: The positive electrode active material on the positive electrode plate includes at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, nickel cobalt aluminum manganese oxide, lithium nickel manganese oxide, lithium cobalt oxide, lithium rich manganese based solid solution or lithium manganese oxide.

12. An electrical device comprising the lithium-ion secondary battery according to any one of claims 1 to 11.

Images