A secondary battery and an electric device

Abstract

The application provides a secondary battery and a power consumption device. The application satisfies the following relation by correlating and limiting the key additive in the electrolyte and the Al content in the positive electrode active material: 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; the complexation between the nitrile additive and the pyridine additive in the electrolyte and the positive electrode and the film forming stability can be effectively improved, and the high-temperature storage stability of the battery is significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a secondary battery and a power consumption device. BACKGROUND

[0002] Since the commercialization of lithium ion batteries, lithium cobalt oxide (LiCoO2) material has become the first choice for positive electrode material of lithium ion batteries for portable consumer electronic products due to its high compaction and high capacity. Developing cobalt lithium batteries with higher energy density can be achieved by increasing the upper limit voltage of the positive electrode. In addition, researchers have begun to use silicon negative electrode materials (4200 mAh / g) with higher specific capacity than graphite (372 mAh / g) to increase the volumetric energy density of the battery in recent years. However, the volume expansion of silicon is close to 400%, which causes low first coulomb efficiency. The current advanced technical means is to use gas deposition method to slow down the expansion of silicon. Cobalt lithium at high voltage brings more serious problems such as cobalt leaching, positive organic by-products, and the like, especially under long calendar test, the silicon particles are broken to expose the material, which further contacts with the electrolyte. In addition to the hard expansion, it also brings 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 the battery. SUMMARY

[0004] The purpose of the present application is to improve the high-temperature storage stability of the secondary battery and the safety performance of the cycle charging and discharging at high voltage.

[0005] To achieve the above purpose, the first aspect of the present application provides a secondary battery, 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 current collector and a positive electrode active layer arranged on at least one surface of the positive electrode current collector; the positive electrode active material in the positive electrode active layer contains Al element; the electrolyte comprises organic solvent, lithium salt, nitrile additive and 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 content of the pyridine additive in the electrolyte;

[0010] N% represents the mass percentage content 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 content N% of the nitrile-based additive in the electrolyte satisfies: 0.1 ≤ N ≤ 4.5.

[0014] As an embodiment of the present application, the mass percentage content P% of the pyridine-based 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, lithium nickel cobalt manganese oxide.

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

[0018]

[0019] In Formula I, R1, R2 are independently selected from fluorine-substituted or non-substituted C1-C3 straight or branched alkyl.

[0020] As a preferred embodiment of the present application, the nitrile-based additive includes at least one compound having a structure formula as follows:

[0021]

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

[0023]

[0024] In Formula II, R1, R2, R3, R4, 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-based additive includes at least one compound having a structure formula as follows:

[0026]

[0027] As an embodiment of the present application, the organic solvent includes at least one of a carbonate solvent, a carboxylic acid ester 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 difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide.

[0029] In a second aspect of the present application, a power consuming device is provided, which includes the secondary battery of the first aspect of the present application.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] By correlating and limiting the relationship between the key additives in the electrolyte and the Al content in the positive active material, the present application can effectively improve the complexation and film 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. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

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

[0034] In the present application, when a numerical interval is involved, the numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value, unless otherwise specified. Further, when a range is referred to as an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all the ranges disclosed herein should be understood to include any and all sub-ranges falling within the range.

[0035] The reagents or instruments used in the present application are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0036] In a first aspect, the present application provides a secondary battery, 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 current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector; the positive electrode active material of the positive electrode active layer containing Al element; the electrolyte comprising 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 content of the pyridine additive in the electrolyte;

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

[0042] Through a large number of studies, the present application adjusts the composition of the electrolyte in the secondary battery, the strong correlation between the positive electrode active materials, and satisfies the above relationship range, which can effectively improve the complexation between the nitrile additive and the pyridine additive in the electrolyte and the positive electrode and the film stability, 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)] can be any one of 0.42, 1.44, 1.78, 6.15, 8.82, 10.48, 13.49, 21.43 or a range formed by any two numerical 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 be specifically any one of 3000 ppm, 4800 ppm, 10000 ppm, 12000 ppm, 16000 ppm or a range formed by any two of the values. It is further preferred to be in the range of 5000-10000 ppm. In the present application, the presence of Al element in the positive electrode active material is not limited, which can be doped or coated. The Al element doped into the crystal 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 content N% of the nitrile-based additive in the electrolyte satisfies: 0.1≤N≤4.5, preferably 2.0≤N≤3.5. The nitrile-based additive can inhibit the reaction of the positive electrode with the non-aqueous electrolyte during high-temperature storage after charging, reduce the generation of gas and the deterioration of battery performance. The addition amount of the nitrile-based additive can be any one of 0.1%, 1.42%, 2%, 3%, 3.5%, 4.5% or a range formed by any two of the values.

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

[0047] In some embodiments, the secondary battery satisfies: 0.3≤100*P / N≤55. Satisfying this relationship, the above-mentioned key additive can be further induced to form a film and complex protection in the positive electrode material, to minimize the storage gas production of the silicon-carbon system, and to further improve the impact resistance of the battery. The calculated value of 100*P / N can be any one of 0.80, 2.50, 6.25, 9.38, 15.00, 22.22, 45.95, 48.15, 60 or a range formed by any two numerical values. Further preferably, 4.5≤100*P / N≤12.

[0048] In the present application, the type of positive electrode active material of the secondary battery is not particularly limited, and the lithium ion positive electrode active material commonly used in the art can be used in the present application to prepare a secondary battery. The layered positive electrode material has important application value in the field of lithium ion batteries due to its 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, which includes at least one of lithium cobaltate (LiCoO2), lithium manganate (LiMnO2), lithium nickelate (LiNiO2), lithium nickel cobalt manganese oxide (general formula: LiNi x Co y Mn z O2, wherein x+y+z=1, and 0

[0049] In some embodiments, the positive electrode active layer further includes a conductive agent and a binder. The type of conductive agent and binder is not particularly limited, and the conductive agent and binder commonly used in the art for secondary batteries can be used in the present application. The conductive agent includes, but is not limited to, at least one of conductive carbon black, graphite, carbon fiber, carbon nanotube, 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, R2 are independently selected from fluorine-substituted or non-substituted C1-C3 straight-chain or branched alkyl.

[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-based additive has a structure shown in Formula II:

[0056]

[0057] In Formula II, R1, R2, R3, R4, R5are independently selected from H atom, halogen atom, C1-C2 alkane or C2-C4 alkene; it is preferred that Formula II contains at least one halogen atom.

[0058] In some embodiments, the pyridine-based additive is selected from at least one compound having a structure shown in the following:

[0059]

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

[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 difluoroxalate borate, lithium tetrafluoroborate, lithium bis-trifluoromethanesulfonimide, lithium bisfluorosulfonimide.

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

[0063] In the present application, the type of positive electrode current collector, negative electrode current collector, and separator is also not limited, and can be selected according to the needs. The current collector material and separator commonly used in the art can be used in the present application.

[0064] In some embodiments, the negative electrode current collector preferably uses copper foil or carbon-coated copper foil, etc.

[0065] The positive electrode current collector can use aluminum, stainless steel, nickel plating layer, titanium, tantalum, etc. metal materials; carbon cloth, carbon paper, etc. carbon materials; composite materials formed by polymers and metal layers, and in some embodiments, the positive electrode current collector preferably uses 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 the solvent can dissolve or disperse the positive electrode active material, the negative electrode active material, the conductive agent, the binder, and the dispersing agent.

[0067] The type of the separator in the secondary battery described in the present application 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 multi-layer composite film modified by coating.

[0068] In some embodiments, the preparation of the secondary battery comprises: stacking the positive electrode sheet, the separator, and the negative electrode sheet in order, with the separator between the positive and negative electrode sheets to play a role of isolation, then winding the stacked sheets into a square bare cell, and then loading the bare cell into a battery shell. After baking at 65-95°C to remove water, the secondary battery is obtained by injecting electrolyte, sealing, standing, hot and cold pressing, formation, clamping, and distribution.

[0069] In some embodiments, the secondary battery can comprise an outer package, which can be a hard shell such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package such as a bag-type soft package. The material of the soft package can be plastic such as one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, etc. The material of the soft package can also be an aluminum plastic film such as a PA layer / Al layer / PP layer composite aluminum plastic film. The shape of the secondary battery is not particularly limited, and it can be cylindrical, square, or any other shape.

[0070] In a second aspect of the present application, a power consuming device is provided, which comprises the secondary battery of the first aspect of the present application. The power consuming device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or an extended range vehicle, etc. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, etc. The electric toy includes a stationary or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, an electric airplane toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator, an electric planer, etc. The embodiments of the present application do not make special limitations on the above devices.

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

[0072] Embodiment 1

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

[0074] Preparation of positive electrode sheet

[0075] The Al-containing compound Al(NO3)3·9H2O was dissolved in anhydrous ethanol to obtain an Al-containing solution, the Al-containing solution and lithium cobaltate were calcined at 300°C for 4h, and then calcined at 750°C in an O2 atmosphere for 6h to obtain a positive electrode active material LiCo (1-x) Al x O2, and the doping amount of the Al element in the positive electrode active material is shown in Table 2; then the positive electrode active material, the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 98.5:0.5:1 to obtain a mixture, which was uniformly mixed and uniformly dispersed in 1-methyl-2-pyrrolidone (NMP) to prepare a uniform black slurry. After the mixed black slurry was coated on both sides of an aluminum foil, baking, rolling, and cutting, a positive electrode tab with a compactness density of 0.33 g / cm 3 was obtained. The other relevant parameters of the related raw materials in the positive electrode tab are shown in Table 2.

[0076] The Al testing method of the positive electrode active material: the battery was disassembled, and ≥3 pieces of positive electrode film pieces were taken from the left, middle and right ends of the positive electrode film pieces, each with an area of not less than 2.5 cm x 2.5 cm, and the positive electrode film pieces were complete and had no powder dropping phenomenon. The above-mentioned positive electrode film pieces meeting the requirements were dissolved in aqua regia (concentrated hydrochloric acid: concentrated nitric acid = 3:1, volume ratio), and inductively coupled plasma (ICP) was used for element monitoring. At this time, the Al content defined as parameter A was monitored.

[0077] Preparation of negative electrode sheet

[0078] The negative electrode active material (SiC), the conductive agent carbon nanotube, the thickening agent carboxymethyl cellulose (CMC) and the binder polyacrylic acid (PAA) were mixed in a mass ratio of 97:0.8:1.2:1, and a solvent deionized water was added. The system was stirred to be uniform under the action of a stirrer to obtain a negative electrode slurry. The negative electrode slurry was uniformly coated on a negative electrode current collector copper foil, and was placed in an oven for drying, rolling and cutting to obtain a negative electrode tab (the compactness density of the tab was 1.60 g / cm 3 );

[0079] Preparation of electrolyte

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

[0081] The nitrile additive is selected from The pyridine additive is selected from

[0082] Table 1: Composition of electrolyte (mass percentage)

[0083] Nitrile-based additive (mass percentage content is denoted as N) 1.8％ Pyridine-based additive (mass percentage content is denoted as P) 0.06％ Lithium salt (mass percentage content is denoted as D) 14％ Organic solvent up to 100%

[0084] Assembly of secondary battery

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

[0086] Examples 2-42 and Comparative Examples 1-8

[0087] A series of secondary batteries are provided and prepared according to the method of Example 1. The differences from Example 1 are shown in Table 2. By adjusting the selection and amount of raw materials and the related preparation process of the battery, 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 is 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 is charged to 4.55V at 0.5C at room temperature (25±2℃), constant voltage to 0.02C, stand for 30min, then discharged to 3.0V at 0.5C, record the discharge capacity of the cell before storage C0, then the secondary battery is charged to 4.55V (full state, 100% SOC) at 0.5C constant current and constant voltage, the cutoff current is 0.02C, the thickness of the battery before high-temperature storage d1 is tested using PPG cell thickness gauge (600g), the cell is placed in an 85℃ constant temperature oven for 6h, after storage is completed, the battery after storage d2 is tested, the battery thickness expansion rate after 85℃ storage for 6h is calculated; after cooling at room temperature for 24h, the cell is discharged to 3.0V at 0.5C constant current again, then charged to 4.55V at 0.5C constant current and constant voltage, record the discharge capacity C1 and charge capacity C2 of the cell after storage, calculate the capacity retention rate and recovery rate of the battery after 85℃ storage for 6h, the calculation formula is as follows:

[0093] 85℃ storage thickness expansion rate = (d2-d1) / d1*100%;

[0094] 85℃ storage capacity retention rate = C1 / C0*100%;

[0095] (2) Thermal shock test:

[0096] Discharge to 3.0V at a given current of 0.2C at 25℃ environmental conditions; stand for 5min; charge to 4.55V at a charge current of 0.2C, when the battery voltage reaches 4.55V, change to 4.55V constant voltage charging until the charge current ≤ cutoff current 0.05C; after standing for 1h, place the cell in an oven, the oven temperature is increased to 135±2℃ at a speed of 5±2℃ / min and kept for 60min, then stop, the judgment standard is that the battery does not catch fire and does not explode.

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

[0098] Table 3

[0099]

[0100]

[0101] From the above results, it can be seen that:

[0102] The present application can effectively improve the complexation and film stability between the nitrile additive and pyridine additive in the electrolyte and the positive electrode by correlating and limiting the relationship between the key additive in the electrolyte and the Al content in the positive active material, and significantly improve the storage stability of the battery at high temperature and high pressure.

[0103] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not 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 can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A secondary battery comprising a positive electrode sheet, an electrolytic solution, a separator, and a negative electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer provided 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 an Al element; the electrolyte includes an organic solvent, a lithium salt, a nitrile-based additive, and a pyridine-based additive; the nitrile-based additive is a trinitrile-based additive; and the secondary battery satisfies the following relationship: 0.3≤A / [100*(N+100P)]≤25; wherein Appm represents the mass content of Al in the positive electrode active material, 3000≤A≤16000; P% represents the mass percentage content of the pyridine-based additive in the electrolyte, 0.02≤P≤3.0; N% represents the mass percentage content of the trinitrile-based additive in the electrolyte, 0.1≤N≤4.

5.

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

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

4. The secondary battery according to claim 1, characterized by At least one of the following characteristics is satisfied: (1) 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; (2) The trinitrile-based additive has a structure shown in Formula I: Formula I; in Formula I, R1, R2 are independently selected from fluorine-substituted or unsubstituted C1-C3 straight-chain or branched alkyl; (3) The pyridine-based additive has a structure shown in Formula II: Formula II; in Formula II, R1, R2, R3, R4, R5 are independently selected from H atoms, halogen atoms, C1-C2 alkane, or C2-C4 alkene.

5. The secondary battery according to claim 4, characterized by At least one of the following characteristics is satisfied: (1) The trinitrile-based additive includes at least one compound having the following structural formula: ； (2) The pyridine-based additive includes at least one compound having the following structural formula: 。 6. The secondary battery according to claim 1, characterized by At least one of the following characteristics is satisfied: (1) The organic solvent includes at least one of a carbonate-based solvent, a carboxylate-based solvent, and an ether-based solvent; (2) The lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobisoxalate phosphate, lithium tetrafluorooxalate phosphate, lithium bisoxalate borate, lithium difluoro oxalate borate, lithium tetrafluoroborate, lithium bis-trifluoromethanesulfonimide, and lithium bis-fluorosulfonimide.

7. An electric device, characterized by The secondary battery of any one of claims 1-6.

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