Lithium ion battery and application thereof

Abstract

The application provides a lithium ion battery and application thereof. The lithium ion battery comprises a negative electrode sheet and an electrolyte. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer arranged on at least one functional surface of the negative electrode current collector. The electrolyte comprises propylene carbonate and a first additive. The specific surface area A of graphite particles in the negative electrode active layer, the mass percentage B of the propylene carbonate in the electrolyte and the mass percentage C of the first additive in the electrolyte satisfy 5 < B / A < 20 and 0.01 < C / B < 0.2. The lithium ion battery has high cycle performance and low-temperature discharge performance.

Description

Technical Field

[0001] This invention relates to a lithium-ion battery and its application, belonging to the field of lithium-ion battery technology. Background Technology

[0002] As the application fields of lithium-ion batteries continue to expand, the performance requirements for lithium-ion batteries in different usage scenarios are also constantly increasing. For example, lithium-ion batteries are required to have good performance in low-temperature environments.

[0003] In existing technologies, ethylene carbonate (EC) is the main organic solvent used in most lithium-ion battery electrolytes. However, since EC has a melting point of 36.4°C, lithium-ion batteries made with electrolytes containing EC exhibit poor performance at low temperatures. Furthermore, propylene carbonate (PC), with a melting point of -48.8°C and a similar molecular structure to EC, is also commonly used as an organic solvent in electrolytes. However, PC can co-intercalate with the graphite anode, easily causing the graphite to peel off and lose its electrochemical activity, thus affecting the cycle performance of the lithium-ion battery. Summary of the Invention

[0004] This invention provides a lithium-ion battery with excellent cycle performance and low-temperature discharge performance.

[0005] The present invention provides an electronic device whose driving source and / or energy storage source has excellent cycle performance and rate performance.

[0006] This invention provides a lithium-ion battery, comprising a negative electrode and an electrolyte;

[0007] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one functional surface of the negative electrode current collector;

[0008] The electrolyte comprises propylene carbonate and a first additive;

[0009] The first additive is selected from at least one of aromatic compounds and pyridine compounds;

[0010] The specific surface area A of the graphite particles in the negative electrode active layer, the mass percentage B of the propylene carbonate in the electrolyte, and the mass percentage C of the first additive in the electrolyte satisfy equations (1) and (2):

[0011] 5<B / A≤20 Equation (1);

[0012] 0.01 < C / B < 0.2 Equation (2).

[0013] The lithium-ion battery as described above, wherein the aromatic compound and / or the pyridine compound has the structure shown in Formula I;

[0014]

[0015] Where X is selected from N and carbon atoms substituted by R6;

[0016] R6 is selected from hydrogen, halogen, substituted or unsubstituted C1-C20 alkyl groups;

[0017] R1, R2, R3, R4, and R5 are independently selected from hydrogen, halogens, substituted or unsubstituted C1-C20 alkyl groups;

[0018] At least one of R1, R2, R3, R4, and R5 is selected from halogens.

[0019] In the lithium-ion battery described above, R1 and R2 are connected in a ring and / or R2 and R3 are connected in a ring;

[0020] And / or, R3 and R4 are connected to form a loop;

[0021] And / or, R4 and R5 are connected to form a ring;

[0022] And / or, R5 and R6 are connected to form a ring;

[0023] And / or, R6 and R1 are connected to form a ring.

[0024] In the lithium-ion battery described above, the aromatic compound is selected from at least one of the following compounds;

[0025]

[0026] And / or, the pyridine compound is selected from at least one of the following compounds;

[0027]

[0028] In the lithium-ion battery described above, A is 0.5-3m. 2 / g; and / or,

[0029] B is 5-25%; and / or,

[0030] C is 0.1-5%.

[0031] In the lithium-ion battery described above, the graphite particles comprise 80-99% by mass, based on the total mass of the negative electrode active layer.

[0032] The lithium-ion battery described above, wherein the electrolyte further includes a fluorinated cyclic carbonate compound;

[0033] The fluorocyclic carbonate compound is selected from at least one of fluoroethylene carbonate, difluoroethylene carbonate, 4-difluoromethylethylene carbonate, and 4-trifluoromethylethylene carbonate.

[0034] In the lithium-ion battery described above, the mass percentage of the fluorinated cyclic carbonate compound is 1-20% based on the total mass of the electrolyte.

[0035] The lithium-ion battery as described above, wherein the electrolyte further includes at least one of ethylene carbonate, 1,2-butenyl carbonate, 4-propyl-1,3-dioxane-2-one, 4,5-dimethyl-1,3-dioxane-2-one, linear carbonate, and linear carboxylic acid ester.

[0036] The linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate;

[0037] The linear carboxylic acid ester is selected from at least one of ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.

[0038] The present invention also provides an electronic device, wherein the driving source and / or energy storage source of the electronic device comprises a lithium-ion battery as described above.

[0039] This invention achieves a lithium-ion battery with excellent cycle performance and low-temperature discharge performance by combining a graphite-containing negative electrode sheet with an electrolyte containing propylene carbonate and a first additive, and by matching the specific surface area A of the graphite particles in the negative electrode active layer, the mass percentage B of the propylene carbonate in the electrolyte, and the mass percentage C of the first additive in the electrolyte to satisfy 5 < B / A ≤ 20 and 0.01 < C / B < 0.2. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 The graphs show the DC impedance (DCIR) curves of lithium-ion batteries in Embodiments 1, 2, and Comparative Example 1 of the present invention under different states of charge (SOC).

[0042] Figure 2 The graph shows the electrochemical impedance spectroscopy (EIS) curves of the lithium-ion batteries of Examples 1, 2 and Comparative Example 1 of the present invention at 50% SOC. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] A first aspect of the present invention provides a lithium-ion battery, comprising a negative electrode and an electrolyte;

[0045] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one functional surface of the negative electrode current collector;

[0046] The electrolyte includes propylene carbonate and a first additive;

[0047] The first additive is selected from at least one of aromatic compounds and pyridine compounds;

[0048] The specific surface area A of the graphite particles in the negative electrode active layer, the mass percentage B of propylene carbonate in the electrolyte, and the mass percentage C of the first additive in the electrolyte satisfy equations (1) and (2):

[0049] 5<B / A≤20 Equation (1);

[0050] 0.01 < C / B < 0.2 Equation (2).

[0051] It is understood that the lithium-ion battery of the present invention includes a negative electrode and an electrolyte. It also includes a positive electrode, a separator, and an outer packaging. The lithium-ion battery of the present invention can be obtained by stacking the positive electrode, separator, and negative electrode to form a battery cell, or by stacking the positive electrode, separator, and negative electrode and then winding them. The battery cell is then placed in the outer packaging, and electrolyte is injected into the outer packaging. The present invention does not particularly limit the specific structure of the positive electrode, separator, and outer packaging; conventional positive electrode, separator, and outer packaging materials in the art can be selected.

[0052] In this invention, the functional surface refers to the two surfaces with the largest area in the current collector that are arranged opposite each other.

[0053] The present invention can obtain a positive electrode sheet by setting a positive electrode active layer on one functional surface of the positive electrode current collector, or by setting a positive electrode active layer on two functional surfaces of the positive electrode current collector.

[0054] The positive electrode active layer of the present invention comprises a positive electrode active material, a conductive agent, and a binder. The positive electrode active material may be selected from one or more of layered lithium transition metal composite oxides, lithium manganese oxide, lithium cobalt oxide, and mixed ternary materials; the chemical formula of the aforementioned layered lithium transition metal composite oxide is Li. 1+x Ni y Co z M (1-y-z) Y2, where -0.1≤x≤1; 0≤y≤1, 0≤z≤1, and 0≤y+z≤1, M is selected from at least one of Mg, Zn, Ga, Ba, Al, Fe, Cr, Sn, V, Mn, Sc, Ti, Nb, Mo and Zr; Y is selected from at least one of O, F, P and S.

[0055] The present invention can obtain a negative electrode sheet by setting a negative electrode active layer on one functional surface of the negative electrode current collector, or by setting a negative electrode active layer on two functional surfaces of the negative electrode current collector.

[0056] The negative electrode active layer of the present invention includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material includes graphite particles. The negative electrode active material may also include at least one of lithium-based materials, carbon-based materials, silicon-based materials, tin-based materials, and their corresponding alloy materials. In some embodiments, the graphite particles are artificial graphite particles.

[0057] The electrolyte of the present invention comprises propylene carbonate and a first additive. The first additive is selected from at least one of aromatic compounds and pyridine compounds.

[0058] In this invention, the specific surface area A of the graphite particles in the negative electrode active layer refers to the effective specific surface area of ​​the graphite particles in the negative electrode active layer, which can be obtained by testing using the BET specific surface area method. The mass percentage B of propylene carbonate in the electrolyte refers to the proportion of the mass of propylene carbonate in the total mass of the electrolyte. The mass percentage C of the first additive in the electrolyte refers to the proportion of the mass of the first additive in the total mass of the electrolyte.

[0059] According to the solution provided by the present invention, by combining a graphite-containing negative electrode sheet with an electrolyte containing propylene carbonate and a first additive, and matching A, B, and C such that 5 < B / A ≤ 20 and 0.01 < C / B < 0.2, a lithium-ion battery with excellent cycle performance and low-temperature discharge performance can be obtained.

[0060] The inventors analyzed the data and concluded that the improved performance of lithium-ion batteries may be due to the following reasons: the low melting point of propylene carbonate in the electrolyte is beneficial to the low-temperature discharge performance of lithium-ion batteries; the first additive in the electrolyte can form a stable SEI film on the surface of the negative electrode active layer, preventing propylene carbonate from co-intercalating with graphite particles, avoiding the graphite particles from being peeled off, and improving the cycle performance of lithium-ion batteries.

[0061] Furthermore, when A, B, and C satisfy 5 < B / A ≤ 20 and 0.01 < C / B < 0.2, the role of graphite particles in the negative electrode active layer, ethylene carbonate in the electrolyte, and the first additive can be fully utilized, thereby improving the low-temperature discharge performance of lithium-ion batteries as well as their cycle performance.

[0062] In some embodiments of the present invention, aromatic compounds and / or pyridine compounds have the structure shown in Formula I;

[0063]

[0064] Where X is selected from N and carbon atoms substituted by R6;

[0065] R6 is selected from hydrogen, halogen, substituted or unsubstituted C1-C20 alkyl groups;

[0066] R1, R2, R3, R4, and R5 are independently selected from hydrogen, halogens, substituted or unsubstituted C1-C20 alkyl groups;

[0067] At least one of R1, R2, R3, R4, and R5 is selected from halogens.

[0068] It is understandable that C1-C20 alkyl refers to C1-C20 straight-chain alkyl (such as methyl, ethyl, propyl, allyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, etc.), C3-C20 branched-chain alkyl (isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, isohexyl, etc.) or C3-C20 cycloalkyl (cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.); halogens can be -F, -Cl, -Br, -I.

[0069] When C1-C20 alkyl groups are substituted, the substituents are halogens or nitro groups.

[0070] In this invention, the C1-C20 alkyl group is further defined as a C1-C10 alkyl group.

[0071] In some embodiments of the present invention, R1 and R2 are connected to form a ring;

[0072] And / or, R2 and R3 are connected to form a loop;

[0073] And / or, R3 and R4 are connected to form a loop;

[0074] And / or, R4 and R5 are connected to form a ring;

[0075] And / or, R5 and R6 are connected to form a ring;

[0076] And / or, R6 and R1 are connected to form a ring.

[0077] Taking the connection of R1 and R2 into a ring as an example, the connection into a ring referred to in this invention means that the atoms in R1 and the atoms in R2 form a ring through bonding.

[0078] As a non-limiting example, the aromatic compound is selected from at least one of the following compounds;

[0079]

[0080] Pyridine compounds are selected from at least one of the following compounds;

[0081]

[0082] In this invention, to further improve the low-temperature discharge performance and cycle performance of lithium-ion batteries, in some embodiments, A is 0.5-3m. 2 / g; and / or, B is 5-25%; and / or, C is 0.1-5%.

[0083] For example, B is 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10.0%, 12.0%, 15.0%, 20.0%, and 25.0%.

[0084] C represents 0.1%, 0.2%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 4.0%, and 5.0%.

[0085] In this invention, to ensure that the lithium-ion battery not only has good rate charge-discharge performance but also good low-temperature discharge performance and cycle performance, in some embodiments, the mass percentage of graphite particles is 80-99% based on the total mass of the negative electrode active layer.

[0086] In some embodiments of the present invention, the electrolyte further includes fluorinated cyclic carbonate compounds;

[0087] The fluorocyclic carbonate compound is selected from at least one of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), 4-difluoromethylethylene carbonate, and 4-trifluoromethylethylene carbonate.

[0088] The inventors discovered that the presence of the aforementioned fluorinated cyclic carbonate compounds in the electrolyte can further improve the cycle performance of lithium-ion batteries. The inventors speculate that this may be because the fluorinated cyclic carbonate compounds can form a stable protective film on the surface of the negative electrode active layer, suppressing gas generation during cycling and thus improving the cycle performance of the lithium-ion battery.

[0089] In this invention, in order to better utilize the role of fluorinated cyclic carbonate compounds and improve the cycle performance of lithium-ion batteries, the mass percentage of fluorinated cyclic carbonate compounds is 1-20% based on the total mass of the electrolyte.

[0090] For example, based on the total mass of the electrolyte, the mass percentage of the fluorocyclic carbonate compound is 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 8.0%, 10.0%, 12.0%, 15.0%, 18.0%, and 20.0%.

[0091] In some embodiments of the present invention, the electrolyte further includes at least one of ethylene carbonate, 1,2-butenyl carbonate, 4-propyl-1,3-dioxane-2-one, 4,5-dimethyl-1,3-dioxane-2-one, linear carbonate, and linear carboxylic acid ester.

[0092] The linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate;

[0093] The linear carboxylic acid ester is selected from at least one of ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.

[0094] In some embodiments of the present invention, the electrolyte further includes lithium salt;

[0095] The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalateborate, and lithium bis(oxalateborate).

[0096] In order to improve the low-temperature discharge performance and cycle performance of lithium-ion batteries while ensuring good charge and discharge performance, in some embodiments, the mass percentage of lithium salt is 13-20% based on the total mass of the electrolyte.

[0097] For example, based on the total mass of the electrolyte, the mass percentage of lithium salt is 3%, 14%, 15%, 16%, 17%, 18%, 19%, and 20 wt%.

[0098] A second aspect of the present invention provides an electronic device, wherein the driving source and / or energy storage source of the electronic device comprises the lithium-ion battery described above.

[0099] The aforementioned lithium-ion batteries can be used as power sources for electronic devices, or as energy storage units for electronic devices. These electronic devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, and energy storage systems.

[0100] Because this electronic device includes the aforementioned lithium-ion battery, it has a long service life and low-temperature discharge performance.

[0101] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0102] Examples and Comparative Examples

[0103] The lithium-ion batteries in the examples and comparative examples were prepared through the following steps:

[0104] 1) Preparation of positive electrode sheet

[0105] Lithium cobalt oxide (LCCO), polyvinylidene fluoride (PVDF), and acetylene black (NMP) were mixed in a mass ratio of 97:1.5:1.5. N-methylpyrrolidone (NMP) was added and the mixture was stirred under vacuum until it formed a uniform and fluid positive electrode slurry. The positive electrode slurry was then uniformly coated onto the two functional surfaces of an aluminum foil. The coated aluminum foil was baked in an oven with five different temperature gradients and then dried in an oven at 120°C for 8 hours. Finally, it was rolled and slit to obtain the desired positive electrode sheet.

[0106] 2) Preparation of negative electrode sheet

[0107] The negative electrode active material graphite, thickener sodium carboxymethyl cellulose (CMC-Na), binder styrene-butadiene rubber, and conductive agent acetylene black were mixed in a mass ratio of 97:1:1:1, and deionized water was added. The mixture was stirred in a vacuum mixer to obtain a negative electrode active slurry. The negative electrode active slurry was uniformly coated on the two functional surfaces of a copper foil with a thickness of 8 μm. The coated copper foil was dried at room temperature and then transferred to an 80°C oven for drying for 10 hours. After cold pressing and slitting, the negative electrode sheet was obtained.

[0108] 3) Preparation of electrolyte

[0109] In an argon-filled glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate and propyl propionate are mixed at a mass ratio of 25:75 to obtain a mixture. Then, fully dried lithium hexafluorophosphate is quickly added to the mixture to form a basic electrolyte.

[0110] Different amounts of propylene carbonate, first additive, and fluorinated cyclic carbonate compound were added to the basic electrolyte to obtain the electrolyte.

[0111] Of which, based on the total mass of the electrolyte, the mass percentage of lithium hexafluorophosphate is 14.5%.

[0112] 4) Preparation of lithium-ion batteries

[0113] After stacking the positive electrode sheet from step 1), the negative electrode sheet from step 2), and the separator in the order of positive electrode sheet, separator, and negative electrode sheet, the cells are wound to obtain a battery cell. The battery cell is placed in an outer packaging aluminum foil, and the electrolyte from step 3) is injected into the outer packaging. After vacuum sealing, settling, formation, shaping, and sorting, a lithium-ion battery is obtained.

[0114] The separator is an 8μm thick polyethylene separator.

[0115] The specific preparation parameters are shown in Table 1.

[0116] In Table 1, A refers to the specific surface area of ​​graphite particles in the negative electrode active layer; EC content refers to the mass percentage of EC based on the total mass of the electrolyte; B refers to the mass percentage of PC based on the total mass of the electrolyte; C refers to the mass percentage of the first additive based on the total mass of the electrolyte; and the content of fluorinated cyclic carbonate compounds refers to the mass percentage of fluorinated cyclic carbonate compounds based on the total mass of the electrolyte.

[0117] The lithium-ion batteries obtained in the examples and comparative examples were subjected to the following tests.

[0118] 1) DC impedance (DCIR) test of battery at different states of charge (SOC)

[0119] The lithium-ion batteries obtained in Examples 1 and 2 and Comparative Example 1 were subjected to charge-discharge tests at a constant temperature of 25°C and a rate of 1.0C / 1.0C. The cutoff voltage range was 3.0V to 4.45V, and the cutoff current during the constant voltage charging stage was 0.025C. The actual battery discharge capacity was recorded, and the state of charge (SOC) of the battery was adjusted based on the actual battery discharge capacity. The DC impedance of the battery under different SOC states was tested. The test results are shown in […]. Figure 1 .

[0120] Figure 1 The graphs show the DC impedance (DCIR) curves of the lithium-ion batteries of Embodiments 1, 2, and Comparative Example 1 of the present invention under different states of charge (SOC). Figure 1As shown, the lithium-ion batteries of Examples 1 and 2 have lower DC internal resistance than the lithium-ion battery of Comparative Example 1, therefore the lithium-ion batteries of Examples 1 and 2 have better low-temperature discharge performance than the lithium-ion battery of Comparative Example 1.

[0121] 2) Electro-acoustic impedance (EIS) test at 50% SOC

[0122] The lithium-ion batteries obtained in Examples 1 and 2 and Comparative Example 1 were subjected to charge-discharge tests at a constant temperature of 25°C and a rate of 1.0C / 1.0C, with a voltage range of 3.0V to 4.45V. The cutoff current during the constant voltage charging phase was 0.025C. The actual battery discharge capacity was recorded, and the battery's state of charge (SOC) was adjusted to 50% based on the actual battery discharge capacity. Under this condition, the battery's AC impedance was tested at a frequency range of 5*10. 4 ~0.1Hz, voltage amplitude is 5mV. For example... Figure 2 As shown.

[0123] Figure 2 The image shows the electrochemical impedance spectroscopy (EIS) curves of the lithium-ion batteries of Examples 1, 2, and Comparative Example 1 of this invention at 50% SOC. Figure 2 As shown, the lithium-ion batteries of Examples 1 and 2 have lower interface impedance than the lithium-ion battery of Comparative Example 1, so the lithium-ion batteries of Examples 1 and 2 have better low-temperature discharge performance than the lithium-ion battery of Comparative Example 1.

[0124] 3) Low-temperature rate discharge performance test

[0125] The lithium-ion batteries in Table 1 were subjected to charge-discharge tests at a constant temperature of 25℃ and a 1.0C rate. The charging cutoff voltage was 4.45V, the cutoff current during the constant voltage charging stage was 0.025C, and the discharge cutoff voltage at a 0.2C rate was 3.0V. The actual battery discharge capacity was recorded as the initial capacity. The batteries were then fully charged at a 1.0C rate, the temperature was set to 0℃, and the batteries were left to stand for 3 hours. Discharge was then performed at different rates, and the low-temperature discharge capacity retention rate was obtained by dividing the discharge capacity by the initial capacity. The test results are shown in Table 2.

[0126] 4) Cyclic performance test

[0127] The obtained batteries were placed in a constant temperature environment of 25℃ and charged and discharged at a rate of 1.0C / 1.0C. The cutoff voltage range was 3.0V to 4.45V, the cutoff current during the constant voltage charging stage was 0.025C, and 500 charge-discharge cycles were performed. The cycle discharge capacity was recorded and divided by the discharge capacity of the first cycle to obtain the cycle capacity retention rate. The test results are shown in Table 2.

[0128] Table 1

[0129]

[0130]

[0131] Table 2

[0132]

[0133]

[0134] As can be seen from Table 2, compared with the lithium-ion battery of the comparative example, the lithium-ion battery of the example has a higher cycle capacity retention rate and low-temperature discharge capacity retention rate.

[0135] Furthermore, as can be seen from Examples 1-9 and Comparative Examples 10-17, when A, B, and C satisfy 5 < B / A < 20 and 0.01 < C / B < 0.2, the lithium-ion battery has a high cycle capacity retention rate and low-temperature discharge capacity retention rate.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium-ion battery, characterized in that, Includes the negative electrode and the electrolyte; The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one functional surface of the negative electrode current collector; The electrolyte comprises propylene carbonate, a first additive, and a fluorocyclic carbonate compound. The first additive is selected from at least one of aromatic compounds and pyridine compounds; the fluorinated cyclic carbonate compound has a mass percentage content of 1-20% based on the total mass of the electrolyte; The specific surface area A of the graphite particles in the negative electrode active layer, the mass percentage B of the propylene carbonate in the electrolyte, and the mass percentage C of the first additive in the electrolyte satisfy equations (1) and (2): 5<B / A≤20 Equation (1); 0.01 < C / B < 0.2 Equation (2); Where A is 0.5-3m 2 / g; B is 5-25%; C is 0.1-5%; Based on the total mass of the negative electrode active layer, the mass percentage of the graphite particles is 80-99%. The aromatic compound and the pyridine compound have the structure shown in Formula I; Formula I, Where X is selected from N and carbon atoms substituted by R6; R6 is selected from hydrogen, halogen, substituted or unsubstituted C1-C20 alkyl groups; R1, R2, R3, R4, and R5 are independently selected from hydrogen, halogens, substituted or unsubstituted C1-C20 alkyl groups; At least one of R1, R2, R3, R4, and R5 is selected from halogens.

2. The lithium-ion battery according to claim 1, characterized in that, R1 and R2 are connected to form a loop; and / or, R2 and R3 are connected to form a loop; And / or, R3 and R4 are connected to form a loop; And / or, R4 and R5 are connected to form a ring; And / or, R5 and R6 are connected to form a ring; And / or, R6 and R1 are connected to form a ring.

3. The lithium-ion battery according to claim 2, characterized in that, The aromatic compound is selected from at least one of the following compounds; Y-1 Y-2 Y-3 Y-4 Y-5 Y-6 Y-7; And / or, the pyridine compound is selected from at least one of the following compounds; Y-8 Y-9 Y-10 Y-11.

4. The lithium-ion battery according to any one of claims 1-3, characterized in that, The fluorocyclic carbonate compound is selected from at least one of fluoroethylene carbonate, difluoroethylene carbonate, 4-difluoromethylethylene carbonate, and 4-trifluoromethylethylene carbonate.

5. The lithium-ion battery according to any one of claims 1-3, characterized in that, The electrolyte further includes at least one of ethylene carbonate, 1,2-butenyl carbonate, 4-propyl-1,3-dioxane-2-one, 4,5-dimethyl-1,3-dioxane-2-one, linear carbonate, and linear carboxylic acid ester. The linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; The linear carboxylic acid ester is selected from at least one of ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.

6. The lithium-ion battery according to claim 4, characterized in that, The electrolyte further includes at least one of ethylene carbonate, 1,2-butenyl carbonate, 4-propyl-1,3-dioxane-2-one, 4,5-dimethyl-1,3-dioxane-2-one, linear carbonate, and linear carboxylic acid ester. The linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; The linear carboxylic acid ester is selected from at least one of ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.

7. An electronic device, characterized in that, The driving source and / or energy storage source of the electronic device includes the lithium-ion battery according to any one of claims 1-6.

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