Secondary battery and electric equipment

Abstract

The invention provides a secondary battery and electric equipment. According to the invention, the relation between the key additive in the electrolyte and the Al content in the positive active material is associated and limited to meet the following conditions: 0.3 < = A / [100 * (N + 100P)] < = 25; a ppm represents the mass content of Al in the positive electrode active material; p% represents the mass percentage content of the pyridine additive in the electrolyte; n% represents the mass percentage content of the nitrile additive in the electrolyte; and the complexing and film-forming stability between the nitrile additive and the pyridine additive in the electrolyte and the positive electrode can be effectively improved, and the high-temperature-resistant storage stability of the battery is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, in particular to a secondary battery and an electrical device. Background Art

[0002] Since the commercialization of lithium-ion batteries, lithium cobalt oxide (LiCoO2) materials have become the preferred positive electrode material for lithium-ion batteries for portable consumer electronic products due to their advantages such as high compaction and high capacity. The development of lithium cobalt oxide batteries with higher energy density can be achieved by increasing the upper limit voltage of the positive electrode. In addition, in recent years, researchers have begun to use silicon negative electrode materials (4200mAh / g) with higher specific capacity than graphite (372mAh / g) to increase the volume energy density of the battery. However, the volume expansion of silicon is close to 400%, resulting in low initial coulomb efficiency. The most advanced technical means at present is the vapor deposition method to slow down the problem of silicon expansion. The cobalt dissolution and positive electrode organic byproducts brought by lithium cobalt oxide under high voltage have a more serious impact on silicon-carbon materials, especially under long calendar tests, the silicon particles are broken to expose the material, and then directly contact with the electrolyte. In addition to its own hard expansion, it also brings about soft expansion of gas production, which indirectly deteriorates the safety performance of the battery.

[0003] Therefore, it is particularly important to improve the storage and safety performance of batteries. Summary of the invention

[0004] The purpose of the present application is to improve the high-temperature storage stability of secondary batteries and the safety performance of cyclic charge and discharge under high voltage.

[0005] To achieve the above-mentioned object, in a first aspect of the present application, a secondary battery is provided, the secondary battery comprising a positive electrode plate, an electrolyte, a separator and a negative electrode plate, the positive electrode plate comprising a positive electrode collector and a positive electrode active layer arranged on at least one surface of the positive electrode collector; the positive electrode active material in the positive electrode active layer contains Al element; the electrolyte comprises an organic solvent, a lithium salt, a nitrile additive and a pyridine additive;

[0006] The secondary battery satisfies the following relationship:

[0007] 0.3≤A / [100*(N+100P)]≤25;

[0008] Wherein, Appm represents the mass content of Al in the positive electrode active material;

[0009] P% represents the mass percentage of the pyridine additive in the electrolyte;

[0010] N% represents the mass percentage of the nitrile additive in the electrolyte.

[0011] As an embodiment of the present application, the secondary battery satisfies: 2.5≤A / [100*(N+100P)]≤5.

[0012] As an embodiment of the present application, the mass content Appm of Al in the positive electrode active material satisfies: 3000≤A≤16000.

[0013] As an embodiment of the present application, the mass percentage N% of the nitrile additive in the electrolyte satisfies: 0.1≤N≤4.5.

[0014] As an implementation scheme of the present application, the mass percentage content P% of the pyridine additive in the electrolyte satisfies: 0.02≤P≤3.0.

[0015] As an embodiment of the present application, the secondary battery satisfies: 0.3≤100*P / N≤55.

[0016] As an embodiment of the present application, the positive electrode active material includes a layered lithium salt, and the layered lithium salt includes at least one of lithium cobaltate, lithium manganate, lithium nickelate, and lithium nickel cobalt manganese oxide.

[0017] As an embodiment of the present application, the nitrile additive has a structure shown in Formula I:

[0018]

[0019] In formula I, R1 and R2 are independently selected from fluorine-substituted or unsubstituted C1-C3 straight or branched alkyl groups.

[0020] As a preferred embodiment of the present application, the nitrile additive includes at least one compound having the following structural formula:

[0021]

[0022] As an embodiment of the present application, the pyridine additive has a structure shown in Formula II:

[0023]

[0024] In formula II, R1, R2, R3, R4, and R5 are independently selected from H atom, halogen atom, C1-C2 alkane or C2-C4 alkene.

[0025] As a preferred embodiment of the present application, the pyridine additive includes at least one compound having the following structural formula:

[0026]

[0027] As an embodiment of the present application, the organic solvent includes at least one of a carbonate solvent, a carboxylate solvent, and an ether solvent.

[0028] As an embodiment of the present application, the lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobisoxalate phosphate, lithium tetrafluorooxalate phosphate, lithium bisoxalate borate, lithium difluorooxalate borate, lithium tetrafluoroborate, bistrifluoromethanesulfonyl imide lithium salt, and lithium bisfluorosulfonyl imide.

[0029] A second aspect of the present application provides an electrical device, wherein the electrical device comprises the secondary battery described in the first aspect of the present application.

[0030] Compared with the prior art, the beneficial effects of this application are:

[0031] By associating and defining the relationship between key additives in the electrolyte and the Al content in the positive electrode active material, the present application can effectively improve the complexation and film formation stability between nitrile additives and pyridine additives in the electrolyte and the positive electrode, and significantly improve the storage stability of the battery under high temperature and high pressure. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0033] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0035] The reagents or instruments used in this application without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0036] In a first aspect of the present application, a secondary battery is provided, the secondary battery comprising a positive electrode sheet, an electrolyte, a separator and a negative electrode sheet, the positive electrode sheet comprising a positive electrode collector and a positive electrode active layer disposed on at least one surface of the positive electrode collector; the positive electrode active material of the positive electrode active layer contains Al element; the electrolyte comprises an organic solvent, a lithium salt, a nitrile additive and a pyridine additive;

[0037] The secondary battery satisfies the following relationship:

[0038] 0.3≤A / [100*(N+100P)]≤25;

[0039] Wherein, A ppm represents the mass content of Al in the positive electrode active material;

[0040] P% represents the mass percentage of the pyridine additive in the electrolyte;

[0041] N% represents the mass percentage of the nitrile additive in the electrolyte.

[0042] Through extensive research, the present application adjusts the composition of the electrolyte in the secondary battery and the strong correlation between the positive electrode active materials to meet the above-mentioned relationship range, which can effectively improve the complexation and film formation stability between the nitrile additives and pyridine additives in the electrolyte and the positive electrode, and significantly improve the storage stability of the battery under high temperature and high pressure.

[0043] In some embodiments, the calculated value of A / [100*(N+100P)] may be any one of 0.42, 1.44, 1.78, 6.15, 8.82, 10.48, 13.49, 21.43 or a range consisting of any two values. The secondary battery further satisfies: 2.5≤A / [100*(N+100P)]≤5.

[0044] In some embodiments, the mass content A ppm of Al in the positive electrode active material satisfies: 3000≤A≤16000. The mass content of Al in the positive electrode active material can specifically be any value of 3000ppm, 4800ppm, 10000ppm, 12000ppm, 16000ppm, or a range consisting of any two values. It is further preferably in the range of 5000 to 10000ppm. In the present application, the presence of the Al element in the positive electrode active material is not limited, and it can be doped or coated. Al element doping into the lattice of the positive electrode active material can stabilize the structure of the positive electrode active material, expand the ion channel, and thus improve the ionic conductivity of the positive electrode active material. Coating Al-containing compounds such as AlF3, Al2O3, etc. on the surface of the positive electrode active material can reduce the occurrence of side reactions, inhibit the dissolution of transition metal ions in the electrolyte, and slow down the collapse of the structure of the positive electrode active material.

[0045] In some embodiments, the mass percentage N% of the nitrile additive in the electrolyte satisfies: 0.1≤N≤4.5, preferably 2.0≤N≤3.5. The nitrile additive can inhibit the reaction between the positive electrode and the non-aqueous electrolyte during high-temperature storage after charging, reduce the generation of gas and the deterioration of battery characteristics. The amount of the nitrile additive added can be any value of 0.1%, 1.42%, 2%, 3%, 3.5%, 4.5%, or a range consisting of any two values.

[0046] In some embodiments, the mass percentage P% of the pyridine additive in the electrolyte satisfies: 0.02≤P≤3.0, preferably 0.08≤P≤0.8. P represents the mass content of the pyridine additive in the electrolyte. The pyridine additive can form a stable low-impedance SEI film at the interface of the positive and negative electrodes at the same time, improve the stability of the positive and negative electrode interfaces, reduce the damage to the negative electrode SEI film caused by the dissolution of transition metal ions, reduce the heat generation caused by the oxidation and decomposition of the electrolyte by the ions in the positive electrode active material, and reduce Joule heat, thereby improving the high-temperature storage performance, cycle performance and safety performance of the battery. The amount of the pyridine additive added can be any value of 0.02%, 0.05%, 0.08%, 0.8%, 1.7%, 2.5%, 2.7%, or a range consisting of any two values.

[0047] In some embodiments, the secondary battery satisfies: 0.3≤100*P / N≤55. Satisfying this relationship can further enable the above-mentioned key additives to better induce film formation and complex protection in the positive electrode material, minimize the storage gas generation of the silicon-carbon system, and further improve the impact resistance of the battery. The calculated value of 100*P / N can be any value of 0.80, 2.50, 6.25, 9.38, 15.00, 22.22, 45.95, 48.15, 60, or a range consisting of any two values. It is further preferred that 4.5≤100*P / N≤12.

[0048] In the present application, there is no particular limitation on the type of positive electrode active material of the secondary battery, and the common lithium ion positive electrode active materials in the field can be used in the present application to prepare secondary batteries. Layered positive electrode materials have important application value in the field of lithium ion batteries due to their high energy density, good cycle stability, simple synthesis, low cost and structural diversity. Therefore, in some embodiments, the positive electrode active material is preferably a layered lithium salt, and the layered lithium salt includes lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMnO2), lithium nickel oxide (LiNiO2), lithium nickel cobalt manganese oxide (general formula LiNi x Co y Mn z O2, wherein x+y+z=1, and 0<x<1, 0<y<1, 0<z<1).

[0049] In some embodiments, the positive electrode active layer further includes a conductive agent and a binder. The types of the conductive agent and the binder are not particularly limited, and the conductive agent and the binder commonly used in the field for secondary batteries can be used in this application. The conductive agent includes but is not limited to at least one of conductive carbon black, graphite, carbon fiber, carbon nanotubes, graphene, and acetylene black. The binder includes but is not limited to at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), styrene-butadiene rubber (SBR) emulsion, and polyimide (PI).

[0050] In some embodiments, the nitrile additive has a structure shown in Formula I:

[0051]

[0052] In formula I, R1 and R2 are independently selected from fluorine-substituted or unsubstituted C1-C3 straight or branched alkyl groups.

[0053] In some embodiments, the nitrile additive is selected from at least one compound having the following structural formula:

[0054]

[0055] In some embodiments, the pyridine additive has a structure shown in Formula II:

[0056]

[0057] In formula II, R1, R2, R3, R4, and R5 are independently selected from H atoms, halogen atoms, C1-C2 alkanes, or C2-C4 alkenes; preferably, formula II contains at least one halogen atom.

[0058] In some embodiments, the pyridine additive is selected from at least one compound having the following structural formula:

[0059]

[0060] In some embodiments, the organic solvent includes at least one of a carbonate solvent, a carboxylate solvent, and an ether solvent.

[0061] In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobisoxalate phosphate, lithium tetrafluorooxalate phosphate, lithium bisoxalate borate, lithium difluorooxalate borate, lithium tetrafluoroborate, bistrifluoromethanesulfonyl imide lithium salt, and lithium bisfluorosulfonyl imide.

[0062] In some embodiments, the negative electrode plate includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material. The present application does not limit the type of negative electrode active material, and the commonly used negative electrode active materials in the art can be used to prepare a secondary battery in the present application. The negative electrode active material includes but is not limited to at least one of a silicon-oxygen material, a carbon material, and a silicon-carbon negative electrode material.

[0063] In the present application, there is no limitation on the types of positive electrode current collector, negative electrode current collector and separator, which can be selected according to the requirements. Common current collector materials and separators in the art can be used in the present application.

[0064] In some embodiments, the negative electrode current collector may preferably be made of copper foil or carbon-coated copper foil.

[0065] The positive electrode current collector may be made of metal materials such as aluminum, stainless steel, nickel plating, titanium, tantalum, etc.; carbon materials such as carbon cloth, carbon paper, etc.; a composite material formed by a polymer and a metal layer. In some embodiments, the positive electrode current collector is preferably made of aluminum foil.

[0066] In some embodiments, the type of solvent used to form the positive electrode slurry and / or the negative electrode slurry is not limited, as long as it is a solvent that can dissolve or disperse the positive electrode active material, the negative electrode active material, the conductive agent, the binder, and the dispersant.

[0067] In the secondary battery described in the present application, the type of the separator is not particularly limited and can be selected according to actual needs. The separator can be a polypropylene film, a polyethylene film, a polyvinylidene fluoride, a spandex film, an aramid film, or a multilayer composite film modified by a coating.

[0068] In some embodiments, the preparation of a secondary battery includes: stacking the positive electrode sheet, the separator, and the negative electrode sheet in order, placing the separator between the positive and negative electrode sheets to play an isolating role, and then winding them into a square bare cell, loading them into a battery casing, and then baking them at 65 to 95°C to remove water, injecting electrolyte, sealing, and obtaining a secondary battery after standing, hot and cold pressing, formation, clamping, capacity division and other processes.

[0069] In some embodiments, the secondary battery may include an outer package, which may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery may also be a soft package, such as a bag-type soft package, and the material of the soft package may be plastic, such as one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, etc., or may be an aluminum-plastic film, such as an aluminum-plastic film composite of a PA layer / Al layer / PP layer. There is no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape.

[0070] The second aspect of the present application provides an electric device, which includes the secondary battery described in the first aspect of the present application. The electric device can be an application device such as a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and an electric tool. The vehicle can be a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for railways, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, and an electric planer, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned devices.

[0071] The following are specific embodiments of the present application, and the technical scheme of the present application is further described in conjunction with the embodiments, but the present application is not limited to these embodiments. The reagents, methods and equipment used in the present application, unless otherwise specified, are conventional reagents, methods and equipment in the art.

[0072] Example 1

[0073] The present application provides a secondary battery, and the specific preparation process includes the following steps:

[0074] Preparation of positive electrode

[0075] The Al-containing compound Al(NO3)3·9H2O was dissolved in anhydrous ethanol to obtain an aluminum-containing solution. The aluminum-containing solution and lithium cobalt oxide were calcined at 300°C for 4 hours, and then calcined in an O2 atmosphere at 750°C for 6 hours to obtain the positive electrode active material LiCo (1-x) Al x The doping amounts of O2 and Al elements in the positive electrode active material are shown in Table 2. Then, the positive electrode active material, the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) are mixed uniformly at a mass ratio of 98.5:0.5:1, and uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to form a uniform black slurry. The mixed black slurry is coated on both sides of the aluminum foil, and then baked, rolled and cut into pieces to obtain a compacted density of 0.33 g / cm 3 For the positive electrode sheet and other relevant parameters of the related raw materials in the positive electrode sheet, please see Table 2;

[0076] Al testing method in positive electrode active material: disassemble the battery, take ≥3 positive electrode membranes from the left, middle and right ends of the positive electrode membrane, each with an area of ​​not less than 2.5 cm × 2.5 cm, and the positive electrode membrane is intact and has no powder falling off. Dissolve the above-mentioned positive electrode membranes that meet the requirements in aqua regia (concentrated hydrochloric acid: concentrated nitric acid = 3:1, volume ratio), and use inductively coupled plasma (ICP) for element monitoring. At this time, the Al content monitored is defined as parameter A;

[0077] Preparation of negative electrode

[0078] The negative electrode active material (SiC), conductive agent carbon nanotubes, thickener carboxymethyl cellulose (CMC), and binder polyacrylic acid (PAA) were mixed in a mass ratio of 97:0.8:1.2:1, and deionized water was added as a solvent. The mixture was stirred in a stirrer until the system was uniform to obtain a negative electrode slurry. The negative electrode slurry was evenly coated on the negative electrode current collector copper foil, placed in an oven for drying, and rolled and cut to obtain a negative electrode sheet (the compaction density of the sheet was 1.60 g / cm 3 );

[0079] Electrolyte preparation

[0080] At room temperature, in a glove box filled with argon (H2O <1ppm, O2 <1ppm), ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain a mixed organic solvent. The molecular sieve is used to remove water to obtain a mixed solvent, and the electrolyte lithium salt (lithium hexafluorophosphate) is added gradually to the obtained mixed solvent, and the mixture is stirred continuously and cooled with dry ice to ensure that the electrolyte temperature does not rise by more than 2°C, and finally a colorless transparent liquid is obtained, and then a nitrile additive and a pyridine additive are added, and the electrolyte is obtained after being mixed evenly; the specific composition of the electrolyte is shown in Table 1;

[0081] Among them, the nitrile additive is selected from The pyridine additive is selected from

[0082] Table 1 Electrolyte composition (mass percentage)

[0083] Nitrile additives (mass percentage content is recorded as N) 1.8％ Pyridine additives (mass percentage content is recorded as P) 0.06％ Lithium salt (mass percentage content is recorded as D) 14％ Organic solvents to 100%

[0084] Secondary battery assembly

[0085] The prepared positive electrode sheet, polypropylene separator, and negative electrode sheet are stacked in order so that the separator is between the positive and negative electrode sheets, and then wound into a battery cell and loaded into a soft package shell. After top and side sealing, liquid injection (electrolyte), formation, sorting and other processes, a lithium-ion secondary battery is obtained.

[0086] Examples 2 to 42, Comparative Examples 1 to 8

[0087] A series of secondary batteries are provided, which are prepared according to the method of Example 1. The differences from Example 1 are shown in Table 2. By adjusting the selection and dosage of raw materials and related preparation processes of the batteries, a series of secondary batteries as shown in Table 2 are obtained.

[0088] Table 2

[0089]

[0090]

[0091] The performance of the secondary batteries obtained in the above examples and comparative examples was tested, and the specific test items, test methods and results are as follows:

[0092] (1) High temperature storage stability, 85℃ high temperature storage for 6h: The secondary battery was placed at room temperature (25±2℃) and charged to 4.55V at 0.5C, constant voltage to 0.02C, and left to stand for 30min. Then, it was discharged to 3.0V at 0.5C, and the discharge capacity C0 before storage was recorded. Then, the secondary battery was charged to 4.55V (full charge state, 100% SOC) at 0.5C constant current and constant voltage, with a cut-off current of 0.02C. A PPG cell thickness gauge (600g) was used to test the battery's stability during high temperature storage. The thickness before storage is d1, the battery cell is placed in an 85℃ constant temperature box for 6 hours, and after the storage is completed, the battery is taken out to test the battery thermal thickness d2 after storage, and the battery thickness expansion rate after the battery cell is stored at 85℃ for 6 hours is calculated; after cooling at room temperature for 24 hours, the battery cell is again discharged at a constant current of 0.5C to 3.0V, and then charged to 4.55V at a constant current and constant voltage of 0.5C, and the discharge capacity C1 and charging capacity C2 of the battery cell after storage are recorded, and the capacity retention rate and recovery rate of the battery after storage at 85℃ for 6 hours are calculated. The calculation formula is as follows:

[0093] Thickness expansion rate after storage at 85°C = (d2-d1) / d1*100%;

[0094] Capacity retention rate after storage at 85°C = C1 / C0*100%;

[0095] (2) Thermal shock test:

[0096] At 25℃, discharge to 3.0V with a given current of 0.2C; leave for 5min; charge to 4.55V with a charging current of 0.2C. When the battery voltage reaches 4.55V, change to 4.55V constant voltage charging until the charging current ≤ the cut-off current of 0.05C; leave for 1h, then put the battery into the oven, increase the oven temperature to 135±2℃ at a rate of 5±2℃ / min, and keep it for 60min before stopping. The judgment standard is that the battery does not catch fire or explode.

[0097] The test results are shown in Table 3.

[0098] Table 3

[0099]

[0100]

[0101] From the above results we can see that:

[0102] By associating and defining the relationship between key additives in the electrolyte and the Al content in the positive electrode active material, the present application can effectively improve the complexation and film formation stability between nitrile additives and pyridine additives in the electrolyte and the positive electrode, and significantly improve the storage stability of the battery under high temperature and high pressure.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than 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, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A secondary battery, comprising a positive electrode sheet, an electrolyte, a separator and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector, characterized in that: The positive electrode active material in the positive electrode active layer contains Al element; the electrolyte includes organic solvent, lithium salt, nitrile additive, pyridine additive; the secondary battery satisfies the following relationship: 0.3≤A / [100*(N+100P)]≤25; Wherein, A ppm represents the mass content of Al in the positive electrode active material; P% represents the mass percentage of the pyridine additive in the electrolyte; N% represents the mass percentage of the nitrile additive in the electrolyte.

2. The secondary battery according to claim 1, characterized in that: The secondary battery satisfies: 2.5≤A / [100*(N+100P)]≤5.

3. The secondary battery according to claim 1, characterized in that: The mass content Appm of Al in the positive electrode active material satisfies: 3000≤A≤16000.

4. The secondary battery according to claim 1, characterized in that: The mass percentage N% of the nitrile additive in the electrolyte satisfies: 0.1≤N≤4.

5.

5. The secondary battery according to claim 1, characterized in that: The mass percentage content P% of the pyridine additive in the electrolyte satisfies: 0.02≤P≤3.

0.

6. The secondary battery according to claim 1, characterized in that: The secondary battery satisfies: 0.3≤100*P / N≤55.

7. The secondary battery according to claim 1, characterized in that: Satisfy at least one of the following characteristics: (1) The positive electrode active material includes a layered lithium salt, and the layered lithium salt includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and lithium nickel cobalt manganese oxide; (2) The nitrile additive has a structure shown in Formula I: In formula I, R1 and R2 are independently selected from fluorine-substituted or unsubstituted C1-C3 straight or branched alkyl groups; (3) The pyridine additive has a structure shown in Formula II: In formula II, R1, R2, R3, R4, and R5 are independently selected from H atom, halogen atom, C1-C2 alkane or C2-C4 alkene.

8. The secondary battery according to claim 7, characterized in that: Satisfy at least one of the following characteristics: (1) The nitrile additive comprises at least one compound having the following structural formula: (2) The pyridine additive includes at least one compound having the following structural formula:

9. The secondary battery according to claim 1, characterized in that: Satisfy at least one of the following characteristics: (1) The organic solvent includes at least one of a carbonate solvent, a carboxylate solvent, and an ether solvent; (2) The lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobisoxalate phosphate, lithium tetrafluorooxalate phosphate, lithium bisoxalate borate, lithium difluorooxalate borate, lithium tetrafluoroborate, bistrifluoromethanesulfonyl imide lithium salt, and lithium bisfluorosulfonyl imide.

10. An electrical device, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 1 to 9.

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