Non-aqueous electrolyte secondary battery and electronic device

Abstract

Provided are a non-aqueous electrolyte secondary battery and an electronic device. The non-aqueous electrolyte secondary battery comprises a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. The negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer provided on at least one surface of the negative electrode current collector. The coating weight of the negative electrode material layer is D g / 1540.25 mm2. The electrolyte comprises fluoroethylene carbonate and a compound of formula (I), wherein R1, R2, R3, R4, R5 and R6 are each independently selected from a fluorine atom or an unsubstituted or fluorine-substituted C1 to C3 alkyl, and at least one of R1, R2, R3, R4, R5 and R6 is selected from a fluorine atom. Based on the mass of the electrolyte, the mass percentage content of the compound of formula (I) is W1%, and the mass percentage content of the fluoroethylene carbonate is W2%. D, W1 and W 2 satisfy: 0.2≤(W1+W2) / D≤100, and 0.10≤D≤0.18. By means of the described arrangement, the cycle life of a non-aqueous electrolyte secondary battery can be prolonged.

Description

Non-aqueous electrolyte secondary batteries and electronic devices Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to a non-aqueous electrolyte secondary battery and electronic device. Background Technology

[0002] Secondary batteries, such as lithium-ion batteries, are widely used in smartphones, wearable devices, consumer drones, and electric vehicles due to their advantages such as high energy density, long cycle life, and no memory effect.

[0003] To achieve higher energy density in rechargeable batteries, existing technologies often increase the operating voltage and the coating weight of the negative electrode material. However, rechargeable batteries using existing technologies experience increased electrolyte consumption during charge-discharge cycles and are prone to insufficient electrolyte transport in the later stages of cycling, leading to purple spots and lithium plating, thus shortening the battery's cycle life. Therefore, extending the cycle life of rechargeable batteries has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide a non-aqueous electrolyte secondary battery and electronic device to extend the cycle life of the non-aqueous electrolyte secondary battery.

[0005] It should be noted that while this application uses lithium-ion batteries as an example of secondary batteries to explain the invention, the secondary batteries in this application are not limited to lithium-ion batteries. The specific technical solution is as follows:

[0006] The first aspect of this application provides a non-aqueous electrolyte secondary battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector. The coating weight of the negative electrode material layer is Dg / 1540.25mm. 2 The electrolyte comprises fluoroethylene carbonate and compound (I):

[0007] In this embodiment, R1, R2, R3, R4, R5, and R6 are each independently selected from fluorine atoms, unsubstituted or fluorine-substituted C1 to C3 alkyl groups, and at least one of R1, R2, R3, R4, R5, and R6 is selected from fluorine atoms. Based on the mass of the electrolyte, the mass content of the compound of formula (I) is W1%, and the mass content of fluoroethylene carbonate is W2%; D, W1, and W2 satisfy: 0.2≤(W1+W2) / D≤100, 0.10≤D≤0.18. The non-aqueous electrolyte secondary battery provided by the first aspect of this application, by adjusting the ratio (W1+W2) / D between the sum of the masses of fluoroethylene carbonate and the compound of formula (I) and the coating weight D of the negative electrode material layer within the range of this application, can make the surface of the negative electrode sheet uniformly filmed, suppress the side reactions between the electrolyte and the negative electrode active material, reduce the consumption of electrolyte and negative electrode active material, accelerate the transport of electrolyte, and improve the wettability of electrolyte to the negative electrode sheet. By controlling the coating weight D of the negative electrode material layer within the range specified in this application, the negative electrode sheet can provide a higher energy density for the non-aqueous electrolyte secondary battery. Consequently, the electrolyte can be rapidly transported during the charge-discharge cycle of the non-aqueous electrolyte secondary battery, thus extending its cycle life.

[0008] In one embodiment of this application, 0.01 ≤ W1 ≤ 10, and / or 0.01 ≤ W2 ≤ 5. Controlling the mass content of the compound of formula (I) and / or fluoroethylene carbonate within the above ranges can extend the cycle life of the non-aqueous electrolyte secondary battery.

[0009] In one embodiment of this application, 0.1 ≤ W1 / W2 ≤ 100. By controlling the ratio W1 / W2 of the mass content W1 of the compound of formula (I) and the mass content W2 of fluoroethylene carbonate within the above range, the contents of the compound of formula (I) and fluoroethylene carbonate have a better match, which is beneficial to further extend the cycle life of the non-aqueous electrolyte secondary battery.

[0010] In one embodiment of this application, the non-aqueous electrolyte secondary battery includes at least one of the following characteristics: (1) 0.5≤(W1+W2) / D≤50; (2) 0.11≤D≤0.16; (3) 0.5≤W1≤5; (4) 0.1≤W2≤1; (5) 0.5≤W1 / W2≤30.

[0011] In one embodiment of this application, the compound of formula (I) includes at least one of the following compounds:

[0012] In one embodiment of this application, the average particle size of the negative electrode active material is Dv50 μm, and Dv50 and D satisfy: 0.8 ≤ D × Dv50 ≤ 3.4. By controlling the value of D × Dv50 within the above range, the coating weight D of the negative electrode material layer and the average particle size Dv50 of the negative electrode active material are well-matched, which is beneficial for the transport and wetting of the electrolyte in the negative electrode sheet, thereby improving the cycle performance of the non-aqueous electrolyte secondary battery and extending its cycle life.

[0013] In one embodiment of this application, 5 ≤ Dv50 ≤ 25. Controlling the average particle size Dv50 of the negative electrode active material within the above range is beneficial for improving the cycle performance of non-aqueous electrolyte secondary batteries and extending their cycle life.

[0014] In one embodiment of this application, 7 ≤ Dv50 ≤ 15. Controlling the average particle size Dv50 of the negative electrode active material within the above range is beneficial for improving the cycle performance of non-aqueous electrolyte secondary batteries and extending their cycle life.

[0015] In one embodiment of this application, the positive electrode includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector. The positive electrode material layer includes a positive electrode active material, which is a nickel-cobalt-manganese ternary material. Based on the total molar amount of nickel, cobalt, and manganese, the molar content of nickel is M3%, where M3 ≥ 50. The positive electrode active material also includes other doping elements, which include at least one of Al, Ta, Zr, B, Ti, or Y. Based on the total mass of nickel, cobalt, and manganese, the mass content of the other doping elements is W4%, where 0 ≤ W4 < 10. Using the above-mentioned nickel-cobalt-manganese ternary material as the positive electrode active material enables non-aqueous electrolyte secondary batteries to have higher energy density and longer cycle life.

[0016] A second aspect of this application provides an electronic device comprising a non-aqueous electrolyte secondary battery as described in any of the foregoing embodiments. Therefore, the electronic device exhibits good performance.

[0017] The beneficial effects of this application are:

[0018] This application provides a non-aqueous electrolyte secondary battery and an electronic device. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector. The coating weight of the negative electrode material layer is Dg / 1540.25mm. 2The electrolyte comprises fluoroethylene carbonate and a compound of formula (I). Based on the mass of the electrolyte, the mass percentage of compound (I) is W1%, and the mass percentage of fluoroethylene carbonate is W2%. D, W1, and W2 satisfy: 0.2 ≤ (W1 + W2) / D ≤ 100, 0.10 ≤ D ≤ 0.18. By adjusting the ratio (W1 + W2) / D between the sum of the masses of fluoroethylene carbonate and the compound of formula (I) and the coating weight D of the negative electrode material layer within the range of this application, a uniform film can be formed on the surface of the negative electrode, suppressing side reactions between the electrolyte and the negative electrode active material, reducing the consumption of electrolyte and negative electrode active material, accelerating electrolyte transport, and improving the wettability of the electrolyte to the negative electrode. Adjusting the coating weight D of the negative electrode material layer within the range of this application enables the negative electrode to provide a higher energy density for non-aqueous electrolyte secondary batteries. Therefore, the electrolyte can be rapidly transferred during the charge-discharge cycle of non-aqueous electrolyte secondary batteries, thus extending the cycle life of non-aqueous electrolyte secondary batteries. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following embodiments are provided to further illustrate this application in detail. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0020] It should be noted that, in the specific embodiments of this application, lithium-ion batteries are used as an example of secondary batteries to explain this application, but the secondary batteries in this application are not limited to lithium-ion batteries.

[0021] The first aspect of this application provides a non-aqueous electrolyte secondary battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the separator is disposed between the positive and negative electrode. The negative electrode includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector. The phrase "a negative electrode material layer disposed on at least one surface of the negative current collector" means that the negative electrode material layer can be disposed on one or both surfaces of the negative current collector, and the "surface" can be a partial or complete area of ​​the surface of the negative current collector. The coating weight of the negative electrode material layer is Dg / 1540.25mm. 2 The electrolyte comprises fluoroethylene carbonate and compound (I):

[0022] In this application, R1, R2, R3, R4, R5, and R6 are each independently selected from fluorine atoms, unsubstituted or fluorine-substituted C1 to C3 alkyl groups, and at least one of R1, R2, R3, R4, R5, and R6 is selected from fluorine atoms; based on the mass of the electrolyte, the mass content of compound (I) is W1%, and the mass content of fluoroethylene carbonate is W2%; D, W1, and W2 satisfy: 0.2 ≤ (W1 + W2) / D ≤ 100, 0.10 ≤ D ≤ 0.18. The "mass content" in this application is also the mass percentage content.

[0023] For example, the value of (W1+W2) / D can be 0.2, 0.5, 2, 10, 13, 19, 25, 30, 37, 40, 50, 60, 61, 68, 72, 80, 85, 90, 92, 100, or any value within any two of the above ranges. Fluoroethylene carbonate and the compound of formula (I) can form a film on the negative electrode sheet. The resulting film can suppress side reactions of the electrolyte and the negative electrode active material, reducing the consumption of both the electrolyte and the negative electrode active material. If the value of (W1+W2) / D is less than 0.2, the sum of the contents of fluoroethylene carbonate and compound (I) is too small relative to the coating weight of the negative electrode material layer. The contents of fluoroethylene carbonate and compound (I) are too low, the probability of uniform film formation on the surface of the negative electrode sheet is small, and the electrolyte and negative electrode active material are prone to side reactions, resulting in excessive consumption of electrolyte and negative electrode active material. If the value of (W1+W2) / D is greater than 100, the sum of the contents of fluoroethylene carbonate and compound (I) is too large relative to the coating weight of the negative electrode material layer. The film formation resistance on the surface of the negative electrode sheet is too large, which will lead to a significant reduction in the cycle performance of the non-aqueous electrolyte secondary battery.

[0024] For example, D can be 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, or any value within any two of the above ranges. If the coating weight D of the negative electrode material layer is less than 0.10, the coating weight of the negative electrode material layer is too small and cannot meet the energy density requirements of non-aqueous electrolyte secondary batteries; if the coating weight D of the negative electrode material layer is greater than 0.18, the coating weight of the negative electrode material layer is too large, and non-aqueous electrolyte secondary batteries can achieve a higher energy density, but the electrolyte is not easily wetted into the negative electrode sheet, and the negative electrode sheet is prone to insufficient wetting, leading to lithium plating problems.

[0025] Overall, the non-aqueous electrolyte secondary battery provided in the first aspect of this application, by controlling the ratio (W1+W2) / D between the sum of the masses of fluoroethylene carbonate and the compound of formula (I) and the coating weight D of the negative electrode material layer within the range of this application, can achieve uniform film formation on the surface of the negative electrode sheet, suppress side reactions between the electrolyte and the negative electrode active material, reduce the consumption of electrolyte and negative electrode active material, accelerate electrolyte transport, and improve the wettability of the electrolyte to the negative electrode sheet. Controlling the coating weight D of the negative electrode material layer within the range of this application enables the negative electrode sheet to provide a higher energy density for the non-aqueous electrolyte secondary battery. Therefore, the electrolyte can be rapidly transported during the charge-discharge cycle of the non-aqueous electrolyte secondary battery, and the cycle life of the non-aqueous electrolyte secondary battery is extended.

[0026] In one embodiment of this application, the C1 to C3 alkyl groups include methyl, ethyl, propyl, or isopropyl.

[0027] In one embodiment of this application, 0.5 ≤ (W1+W2) / D ≤ 50. For example, the value of (W1+W2) / D is 0.5, 2, 10, 13, 19, 25, 30, 37, 40, 44, 50, or any value between any two of the above ranges. Adjusting the value of (W1+W2) / D within the above range is beneficial for further improving the uniformity of the film formation on the surface of the negative electrode, improving the wettability of the electrolyte to the negative electrode, and thus further extending the cycle life of the non-aqueous electrolyte secondary battery.

[0028] In one embodiment of this application, 0.11 ≤ D ≤ 0.16. For example, D is 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, or any value between any two of the above ranges. Controlling the coating weight D of the negative electrode material layer within the above range helps to better match the coating weight of the negative electrode material layer with the content of fluoroethylene carbonate and compound (I) in the electrolyte, thereby further extending the cycle life of the non-aqueous electrolyte secondary battery.

[0029] In one embodiment of this application, 0.01 ≤ W1 ≤ 10. For example, W1 is 0.01, 0.5, 1, 2, 2.2, 3, 4, 4.6, 5, 5.3, 6, 7, 7.1, 8, 8.6, 9, 9.4, 10, or any value between any two of the above ranges. The compound of formula (I) can form a film on the surface of the negative electrode and does not easily generate gas. Controlling the mass content W1 of the compound of formula (I) within the above range is beneficial to the uniformity of film formation on the surface of the negative electrode, and it is not easy to generate gas during the film formation process, thereby helping to extend the cycle life of the non-aqueous electrolyte secondary battery.

[0030] In one embodiment of this application, 0.5 ≤ W1 ≤ 5. For example, W1 is 0.5, 1, 1.4, 2, 2.2, 3, 3.6, 4, 4.6, 5, or any value between any two of the above ranges. Controlling the mass content W1 of the compound of formula (I) within the above range is beneficial for further extending the cycle life of the non-aqueous electrolyte secondary battery.

[0031] In one embodiment of this application, 0.01 ≤ W2 ≤ 5. For example, W2 is 0.01, 0.1, 0.4, 0.7, 1, 1.2, 1.6, 2, 2.2, 2.7, 3, 3.3, 3.8, 4, 4.5, 5, or any value between any two of the above ranges. Fluoroethylene carbonate exhibits good film-forming properties on the surface of the negative electrode. Controlling the mass content W2 of fluoroethylene carbonate within the above range is beneficial for the uniformity of film formation on the surface of the negative electrode, reducing the consumption of negative electrode active material and electrolyte, thereby extending the cycle life of the non-aqueous electrolyte secondary battery.

[0032] In one embodiment of this application, 0.1 ≤ W2 ≤ 1. For example, W2 is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any value between any two of the above ranges. Controlling the mass content W2 of fluoroethylene carbonate within the above range is beneficial for further improving the uniformity of the film formation on the surface of the negative electrode, reducing the consumption of negative electrode active material and electrolyte, thereby further extending the cycle life of the non-aqueous electrolyte secondary battery.

[0033] In one embodiment of this application, 0.01 ≤ W1 ≤ 10, and 0.01 ≤ W2 ≤ 5. For example, W1 is 0.01, 0.5, 1, 2, 2.2, 3, 4, 4.6, 5, 5.3, 6, 7, 7.1, 8, 8.6, 9, 9.4, 10, or any value between any two of the above ranges. W2 is 0.01, 0.1, 0.4, 0.7, 1, 1.2, 1.6, 2, 2.2, 2.7, 3, 3.3, 3.8, 4, 4.5, 5, or any value between any two of the above ranges. Controlling the mass content W1 of the compound of formula (I) and the mass content W2 of fluoroethylene carbonate within the above ranges is beneficial for film formation on the surface of the negative electrode, thereby suppressing side reactions of the electrolyte and the negative electrode active material, reducing the consumption of the electrolyte and the negative electrode active material, and thus extending the cycle life of the non-aqueous electrolyte secondary battery.

[0034] In one embodiment of this application, 0.1 ≤ W1 / W2 ≤ 100. For example, the value of W1 / W2 is 0.1, 1, 5, 10, 12, 17, 20, 22, 28, 31, 37, 42, 50, 56, 60, 71, 77, 80, 82, 86, 90, 92, 100, or any value between any two of the above ranges. Fluoroethylene carbonate has good film-forming properties on the surface of the negative electrode, but it is unstable and prone to gas generation at high temperatures (≥60°C). The compound of formula (I) can form a film on the surface of the negative electrode and does not easily generate gas. By controlling the ratio W1 / W2 of the mass content W1 of compound (I) and the mass content W2 of fluoroethylene carbonate within the above range, the contents of compound (I) and fluoroethylene carbonate exhibit good matching, which is beneficial for good film formation on the surface of the negative electrode. The formed film can suppress side reactions between the electrolyte and the negative electrode active material, reduce the consumption of electrolyte and negative electrode active material, accelerate electrolyte transport, and improve the wettability of the electrolyte on the negative electrode. This extends the cycle life of the non-aqueous electrolyte secondary battery.

[0035] In one embodiment of this application, 0.5 ≤ W1 / W2 ≤ 30. For example, the value of W1 / W2 is 0.5, 1, 2, 5, 10, 12, 16, 17, 20, 22, 26, 28, 30, or any value between any two of the above ranges. By controlling the ratio W1 / W2 of the mass content W1 of compound (I) and the mass content W2 of fluoroethylene carbonate within the above range, the content of compound (I) and fluoroethylene carbonate has a better match, which is beneficial to further extend the cycle life of the non-aqueous electrolyte secondary battery.

[0036] In one embodiment of this application, the compound of formula (I) includes at least one of the following compounds:

[0037] Using the above-mentioned compounds of formula (I) is beneficial for uniform film formation on the surface of the negative electrode. The film formed can suppress the side reactions between the electrolyte and the negative electrode active material, reduce the consumption of electrolyte and negative electrode active material, and thus improve the cycle life of non-aqueous electrolyte secondary batteries.

[0038] In one embodiment of this application, the viscosity of the electrolyte is Q mPa·s, where 4 ≤ Q ≤ 7.5. For example, Q can be 4, 4.5, 5, 5.6, 6, 6.2, 6.6, 7, 7.5, or any value within any two of the above ranges. Controlling the electrolyte viscosity within the above range is beneficial for achieving a faster transport rate, better wettability of the electrolyte to the negative electrode, and ultimately, for extending the lifespan of the non-aqueous electrolyte secondary battery.

[0039] In one embodiment of this application, the electrolyte further includes a lithium salt and a solvent. This application does not particularly limit the types of lithium salts and solvents, as long as they achieve the purpose of this application. For example, the lithium salt includes, but is not limited to, at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalateborate), or lithium difluorooxalateborate. The solvent includes, but is not limited to, at least one of carbonate solvents, carboxylic acid ester solvents, or fluorinated solvents. This application does not particularly limit the types of carbonate solvents, carboxylic acid ester solvents, and fluorinated solvents, as long as they achieve the purpose of this application. For example, carbonate solvents may be at least one of chain carbonate compounds, cyclic carbonate compounds, or fluorinated carbonate compounds. The aforementioned chain carbonate compounds may include, but are not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), or methyl ethyl carbonate (MEC). Cyclic carbonate compounds may include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), or vinyl ethylene carbonate (VEC). Fluorinated carbonate compounds may include, but are not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate. The aforementioned carboxylic acid ester solvents may include, but are not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolactone, valproic acid lactone, mevalonate lactone, or caprolactone. The aforementioned fluorinated solvents include, but are not limited to, at least one of trifluoroethanol acetate or difluoroethanol acetate. This application does not impose any particular limitation on the content of lithium salt and solvent, as long as the purpose of this application is achieved. For example, based on the mass of the electrolyte, the mass content of lithium salt is 10% to 16%, and the mass content of solvent is 74% to 89.9%.

[0040] In one embodiment of this application, the electrolyte comprises fluoroethylene carbonate, a compound of formula (I), a lithium salt, and a solvent. Based on the mass of the electrolyte, the mass content of fluoroethylene carbonate is 0.01% to 5%, the mass content of compound of formula (I) is 0.01% to 10%, the mass content of lithium salt is 10% to 16%, and the mass content of solvent is 74% to 89.9%.

[0041] In one embodiment of this application, the average particle size of the negative electrode active material is Dv50 μm, and Dv50 and D satisfy: 0.8 ≤ D × Dv50 ≤ 3.4. For example, the value of D × Dv50 is 0.8, 1.0, 1.4, 1.7, 2.0, 2.2, 2.6, 3.0, 3.1, 3.4, or any value between any two of the above ranges. By controlling the value of D × Dv50 within the above range, the coating weight D of the negative electrode material layer and the average particle size Dv50 of the negative electrode active material are matched. While providing a high energy density, the negative electrode sheet also has suitable porosity between the particles of the negative electrode active material, which is beneficial for the transport and wetting of the electrolyte in the negative electrode sheet. This improves the cycle performance of the non-aqueous electrolyte secondary battery and extends its cycle life.

[0042] In one embodiment of this application, 5 ≤ Dv50 ≤ 25. For example, Dv50 is 5, 7, 9, 10, 11, 13, 14, 16, 18, 20, 22, 23, 25, or any value between any two of the above ranges. By controlling the average particle size Dv50 of the negative electrode active material within the above range, the negative electrode active material has a suitable particle size, resulting in a lower probability of scratches during the processing of the negative electrode sheet. This also increases the number of contact points between the particles of the negative electrode active material, which is beneficial for improving the cycle performance of the non-aqueous electrolyte secondary battery and extending its cycle life.

[0043] In one embodiment of this application, 7 ≤ Dv50 ≤ 15. For example, Dv50 is 7, 8, 9, 10, 11, 12, 13, 14, 15, or any value between any two of the above ranges. Controlling the average particle size Dv50 of the negative electrode active material within the above range is beneficial to further improve the cycle performance of non-aqueous electrolyte secondary batteries and extend their cycle life.

[0044] In this application, "average particle size Dv50 of the negative electrode active material" refers to the particle size that, starting from the smallest particle size, reaches 50% of the total volume in the particle size distribution of the negative electrode active material on a volume basis.

[0045] This application does not impose any particular restrictions on the method of controlling the average particle size Dv50 of the negative electrode active material, as long as the purpose of this application can be achieved. For example, it can be achieved through crushing or sieving.

[0046] In one embodiment of this application, the positive electrode includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector. The phrase "positive electrode material layer disposed on at least one surface of the positive current collector" means that the positive electrode material layer can be disposed on one or both surfaces of the positive current collector, and the "surface" can be a partial or complete area of ​​the surface of the positive current collector. The positive electrode material layer includes a positive electrode active material, which is a nickel-cobalt-manganese ternary material. Based on the total molar amount of the three elements (nickel, cobalt, and manganese), the molar content of nickel is M3%, where M3 ≥ 50. Further, 50 ≤ M3 ≤ 99. The aforementioned "molar content" is also known as molar percentage content. The positive electrode active material also includes other doping elements, which include at least one of Al, Ta, Zr, B, Ti, or Y. Based on the total mass of the three elements (nickel, cobalt, and manganese), the mass content of the other doping elements is W4%, where 0 ≤ W4 < 10. The aforementioned "three elements (nickel, cobalt, and manganese)" refers to nickel, cobalt, and manganese. For example, W4 can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9.9, or any value within any two of the above ranges. Nickel-cobalt-manganese ternary materials with nickel content and the content and types of other doping and coating elements within the above ranges exhibit high capacity, good structural stability, and good cycle performance. Using these nickel-cobalt-manganese ternary materials as positive electrode active materials enables non-aqueous electrolyte secondary batteries to have higher energy density and longer cycle life.

[0047] In one embodiment of this application, the nickel-cobalt-manganese ternary material includes NCM523 (LiNi 0.5 Co 0.2 Mn 0.3 O2)NCM613(LiNi 0.6 Co 0.1 Mn 0.3 O2), NCM622(LiNi) 0.6 Co 0.2 Mn 0.2 O2), Ni70(LiNi) 0.7 Co 0.1 Mn 0.2 O2)Ni71(LiNi 0.71 Co 0.14 Mn 0.15 O2), Ni90(LiNi) 0.9 Co 0.05 Mn 0.05 O2)Ni91(LiNi 0.91 Co 0.04 Mn 0.05 O2), Ni92(LiNi) 0.92 Co 0.03 Mn 0.05 O2), Ni93(LiNi)0.93 Co 0.02 Mn 0.05 O2), Ni94(LiNi) 0.94 Co 0.01 Mn 0.05 O2), Ni95(LiNi) 0.95 Co 0.01 Mn 0.04 O2) or NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2).

[0048] This application does not impose any particular restrictions on the preparation method of positive electrode active materials containing other doped coating elements, as long as the purpose of this application can be achieved. For example, the preparation method of positive electrode active materials containing other doped coating elements includes, but is not limited to, the following steps: (1) preparing a hydroxide precursor containing Ni, Co, and Mn elements by hydrothermal method; (2) thoroughly mixing the prepared hydroxide precursor with a lithium source and a dopant compound, and then sintering at high temperature to obtain a positive electrode active material containing other doped coating elements. This application does not impose any particular restrictions on the type of hydroxide precursor mentioned above, as long as the purpose of this application can be achieved. For example, the hydroxide precursor may include, but is not limited to, Ni. 0.6 Co 0.1 Mn 0.3 (OH)2. This application does not impose any particular restrictions on the type of lithium source, as long as it can achieve the purpose of this application. For example, the lithium source may include, but is not limited to, Li2CO3. This application does not impose any particular restrictions on the molar ratio of the hydroxide precursor and the lithium source. Those skilled in the art can select the appropriate ratio based on the chemical formula of the nickel-cobalt-manganese ternary material to be prepared, as long as it can achieve the purpose of this application. This application does not impose any particular restrictions on the amount of dopant compound added. Those skilled in the art can select the appropriate ratio based on the content of other doping and coating elements required, as long as it can achieve the purpose of this application. This application does not impose any particular restrictions on the process parameters of high-temperature sintering in step (2) above, as long as it can achieve the purpose of this application. For example, the high-temperature sintering temperature is 800℃ to 900℃, and the high-temperature sintering time is 10h to 14h.

[0049] This application does not impose any particular restrictions on the method of controlling the content of other doped and coated elements in the positive electrode active material, as long as the purpose of this application can be achieved. For example, it can be achieved by controlling the raw material ratio, temperature, etc.

[0050] The present application has no particular limitation on the negative electrode current collector, as long as the objective of the present application can be achieved. For example, the negative electrode current collector may comprise copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam or copper foam. The negative electrode material layer of the present application comprises a negative electrode active material. The present application has no particular limitation on the type of the negative electrode active material, as long as the objective of the present application can be achieved. For example, the negative electrode active material may comprise natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0<x<2), Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO₂, lithium titanate Li₄Ti₅O with spinel structure 12 , at least one of Li-Al alloy or metallic lithium. In the present application, there is no particular limitation on the thicknesses of the negative electrode current collector and the negative electrode material layer, as long as the objective of the present application can be achieved. For example, the thickness of the negative electrode current collector is 6 μm to 10 μm, and the thickness of the negative electrode material layer is 30 μm to 130 μm. Optionally, the negative electrode material layer may further comprise at least one of a negative electrode conductive agent, a thickener or a negative electrode binder. The present application has no particular limitation on the types of the negative electrode conductive agent, thickener and negative electrode binder in the negative electrode material layer, as long as the objective of the present application can be achieved. The present application has no particular limitation on the mass ratio of the negative electrode active material, the negative electrode conductive agent, the thickener and the negative electrode binder in the negative electrode material layer, as long as the objective of the present application can be achieved. For example, the mass ratio of the negative electrode active material, the negative electrode conductive agent, the thickener and the negative electrode binder in the negative electrode material layer is (95~98):(0~1.5):(0~3.0):(1.0~2.0).

[0051] The present application has no particular limitation on the positive electrode current collector, as long as the objective of the present application can be achieved. For example, the positive electrode current collector may comprise aluminum foil or aluminum alloy foil. In the present application, there is no particular limitation on the thicknesses of the positive electrode current collector and the positive electrode material layer, as long as the objective of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, and the thickness of a single-layer positive electrode material layer is 30 μm to 120 μm. Optionally, the positive electrode material layer may further comprise at least one of a positive electrode conductive agent or a positive electrode binder. The present application has no particular limitation on the types of the positive electrode conductive agent and the positive electrode binder in the positive electrode material layer, as long as the objective of the present application can be achieved. The present application has no particular limitation on the mass ratio of the positive electrode active material, the positive electrode conductive agent and the positive electrode binder in the positive electrode material layer, which can be selected by those skilled in the art according to actual needs, as long as the objective of the present application can be achieved. For example, the mass ratio of the positive electrode active material, the positive electrode conductive agent and the positive electrode binder in the positive electrode material layer is (94.0~97.9):(0.8~3.0):(1.0~3.0).

[0052] This application does not impose any particular limitation on the diaphragm, as long as it achieves the purpose of this application. For example, the diaphragm material may include, but is not limited to, at least one of polyethylene (PE), polyolefins (PO) primarily composed of polypropylene (PP), polyester (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid. The type of diaphragm may include at least one of woven membrane, nonwoven membrane, microporous membrane, composite membrane, rolled membrane, or spun membrane. This application does not impose any particular limitation on the thickness of the diaphragm, as long as it achieves the purpose of this application.

[0053] The non-aqueous electrolyte secondary battery of this application also includes a packaging bag, in which the positive electrode, negative electrode, separator, and electrolyte are contained. This application does not impose any particular limitation on the type of packaging bag, as long as it achieves the purpose of this application.

[0054] The non-aqueous electrolyte secondary battery described in this application is not particularly limited and may include any device in which an electrochemical reaction occurs. For example, a non-aqueous electrolyte secondary battery may include, but is not limited to, lithium metal secondary batteries, lithium-ion secondary batteries (lithium-ion batteries), lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0055] This application does not impose any particular limitation on the preparation method of non-aqueous electrolyte secondary batteries. Any preparation method known in the art can be used, as long as it achieves the purpose of this application. For example, the preparation method of a non-aqueous electrolyte secondary battery includes, but is not limited to, the following steps: stacking a separator, a positive electrode, a separator, and a negative electrode in sequence, and then winding, folding, or performing other operations as needed to obtain a wound electrode assembly; placing the electrode assembly in a packaging bag; injecting electrolyte into the packaging bag and sealing it to obtain a secondary battery; or stacking a separator, a positive electrode, a separator, and a negative electrode in sequence, then fixing the four corners of the entire stacked structure to obtain a stacked electrode assembly; placing the electrode assembly in a packaging bag; injecting electrolyte into the packaging bag and sealing it to obtain a secondary battery.

[0056] A second aspect of this application provides an electronic device comprising a non-aqueous electrolyte secondary battery as described in any of the foregoing embodiments. Therefore, the electronic device exhibits good performance.

[0057] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. For example, the electronic device may include, but is not limited to: laptop computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors.

[0058] Example

[0059] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below.

[0060] Test methods and equipment:

[0061] Testing the coating weight of the negative electrode material layer:

[0062] The lithium-ion battery was discharged to 3.0V at 0.5C and then disassembled to obtain the negative electrode sheet. The negative electrode sheet was immersed in dimethyl carbonate (DMC) solution for 4 hours, then dried, and a piece with an area of ​​B mm was cut off. 2 The negative electrode sample was weighed on a balance and recorded as q1. Then, the negative electrode material layer on the negative electrode was washed, and the negative electrode current collector was weighed on a balance and recorded as q2. The above Bmm 2 =1540.25mm 2 ;

[0063] If it is a negative electrode sheet with a negative electrode material layer coated on one side, D=(q1-q2) / B.

[0064] If it is a negative electrode sheet with a negative electrode material layer coated on both sides, D=(q1-q2) / 2B.

[0065] Testing of the average particle size of the negative electrode active material:

[0066] The average particle size Dv50 of the negative electrode active material was determined using a laser particle size analyzer.

[0067] Testing of elemental content in nickel-cobalt-manganese ternary materials:

[0068] After discharging the lithium-ion battery to 3.0V at 0.5C, the positive electrode sheet is obtained. It is then cleaned three times with high-purity anhydrous DMC, soaked for 8 hours each time, and then left to stand in a vacuum drying oven for 12 hours. The positive active material layer is scraped off the positive electrode sheet and then tested with an inductively coupled plasma optical emission spectrometer (ICP) to obtain the content of each element in the nickel-cobalt-manganese ternary material.

[0069] Cycle life testing of non-aqueous electrolyte secondary batteries:

[0070] At 25℃, the lithium-ion battery was charged at a constant current of 1.2C to 4.2V, then charged at a constant voltage of 4.2V to a current of 0.7C, then charged at a constant current of 0.7C to 4.4V, and then charged at a constant voltage of 4.4V to a current of 0.05C. After resting for 5 minutes, it was discharged at a constant current of 0.5C to 3.0V. This was the first cycle, and the discharge capacity was recorded. Multiple cycles were performed following the above process, and the discharge capacity of the lithium-ion battery was measured after each cycle. Using the initial discharge capacity as 100%, the charge-discharge cycles were repeated until the discharge capacity retention rate decreased to 80% of the initial discharge capacity. The number of cycles was then recorded. The number of cycles is used as an indicator of the cycle life of the lithium-ion battery. The more cycles, the longer the cycle life of the lithium-ion battery.

[0071] Example 1-1

[0072] <Preparation of Electrolyte>

[0073] In a dry argon atmosphere, ethylene carbonate and diethyl carbonate are mixed uniformly at a mass ratio of 3:7 to obtain a solvent. Fluoroethylene carbonate and compound I-1 of formula (I) are then added separately to the uniformly mixed solvent. Lithium salt LiPF6 is then added, dissolved, and mixed uniformly to obtain the electrolyte. Based on the mass of the electrolyte, the mass content of compound (I) is W1 = 2%, the mass content of fluoroethylene carbonate is W2 = 0.5%, the mass content of lithium salt is 12%, and the remainder is solvent.

[0074] <Preparation of Negative Electrode Sheets>

[0075] The negative electrode active material is artificial graphite, and the binder is styrene-butadiene rubber (SBR, with a weight average molecular weight of 5×10⁻⁶). 6Thickener sodium carboxymethyl cellulose was mixed at a mass ratio of 95:2:3, deionized water was added, and the mixture was stirred evenly under vacuum to obtain a negative electrode slurry with a solid content of 75 wt%. The negative electrode slurry was uniformly coated onto one surface of a 5 μm thick copper foil current collector. The copper foil was dried at 85°C for 4 hours to obtain a negative electrode sheet with a single-sided negative electrode material layer. The above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided negative electrode material layer. After cold pressing, cutting, and slitting, a negative electrode sheet with a size of 76.6 mm × 875 mm was obtained. The coating weight of the negative electrode material layer was D = 0.15 g / 1540.25 mm. 2 The average particle size of the negative electrode active material is Dv50 = 11 μm.

[0076] <Preparation of the positive electrode>

[0077] The positive electrode active material is a nickel-cobalt-manganese ternary material (LiNi). 0.6 Co 0.1 Mn 0.3 O2), positive electrode conductive agent acetylene black, positive electrode binder polyvinylidene fluoride (PVDF, weight average molecular weight 5×10⁻⁶), and positive electrode binder polyvinylidene fluoride (PVDF, weight average molecular weight 5×10⁻⁶). 5 The materials were mixed at a mass ratio of 94:3:3, with N-methylpyrrolidone (NMP) added as a solvent. The mixture was stirred under vacuum until a homogeneous positive electrode slurry with a solid content of 75 wt% was obtained. The positive electrode slurry was uniformly coated onto one surface of a 6 μm thick aluminum foil current collector and dried at 90°C to obtain a positive electrode sheet with a single-sided coating of positive electrode material (80 μm thick). The above steps were then repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coating of positive electrode material. After cold pressing and slitting, positive electrode sheets with dimensions of 74 mm × 851 mm were obtained for later use. In the nickel-cobalt-manganese ternary material, the molar content of nickel M3 = 60%, and the mass content of other doping and coating elements W4 = 0%.

[0078] <Preparation of the diaphragm>

[0079] The adhesive PVDF (weight average molecular weight of 5×10) 5 Inorganic alumina particles were mixed at a mass ratio of 1:2, and NMP was added as a solvent to prepare an inorganic layer slurry with a solid content of 12 wt%. The slurry was stirred evenly and then uniformly coated onto one surface of a 5 μm thick polyethylene substrate. The substrate was then dried at 85°C for 4 hours to obtain a diaphragm with a single-sided inorganic layer coating thickness of 2 μm. PVDF was then added to NMP solvent and stirred evenly to prepare a polymer layer slurry with a solid content of 25 wt%. This polymer layer slurry was then uniformly coated onto the surface of the inorganic layer, with a surface density of 0.15 mg / cm³. 2Then, it is dried at 85℃ for 4 hours. Finally, a polymer layer slurry is uniformly coated on the other surface of the polyethylene substrate. The areal density of the polymer layer slurry is 0.15 mg / cm³. 2 Then, it is dried at 85°C for 4 hours to obtain a diaphragm with an inorganic layer and a polymer layer on one side and only a polymer layer on the other side.

[0080] <Preparation of Lithium-ion Batteries>

[0081] The separator, negative electrode, and positive electrode prepared above are stacked and wound in sequence to obtain a wound electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dried, and then injected with electrolyte. After vacuum sealing, standing, formation, degassing, and edge trimming, a lithium-ion battery is obtained. Formation steps: constant current charging at 0.02C to 3.3V, and then constant current charging at 0.1C to 3.6V.

[0082] Examples 1-2 to Examples 1-5

[0083] Except for adjusting the coating weight D of the negative electrode material layer according to Table 1, the rest is the same as in Example 1-1.

[0084] Examples 1-6 to Examples 1-25

[0085] Except for the mass content W1 of the compound according to formula (I) and / or the mass content W2 of fluoroethylene carbonate according to Table 1, the rest is the same as in Examples 1-1.

[0086] When the mass content of compound (I) W1 and / or the mass content of fluoroethylene carbonate W2 changes, the mass content of lithium salt remains unchanged, while the mass content of solvent changes accordingly. The sum of the mass contents of compound (I), fluoroethylene carbonate, lithium salt and solvent is 100%.

[0087] Examples 1-26 to Examples 1-29

[0088] Except for the types of compounds adjusted according to formula (I) in Table 1, the rest are the same as in Examples 1-1.

[0089] Examples 2-1 to 2-9

[0090] Except for adjusting the relevant preparation parameters according to Table 2, the rest is the same as in Examples 1-1.

[0091] Examples 3-1 to 3-3

[0092] Except for adjusting the type of positive electrode active material according to Table 3 and changing the mass content of nickel, everything else is the same as in Example 1-1.

[0093] Examples 3-4

[0094] <Preparation of Positive Electrode Active Materials>

[0095] According to the chemical formula LiNi 0.6 Co 0.1 Mn 0.3 O2 will react with the hydroxide precursor Ni 0.6 Co 0.1 Mn 0.3 After thoroughly mixing (OH)2 and Li2CO3 (Li: transition metal molar ratio of 1.05, the transition metal elements being Ni, Co, and Mn), Al2O3 is added and mixed evenly to obtain a mixture in which the total mass ratio of Al to Ni, Co, and Mn is 5:100. The resulting mixture is then placed in a tube furnace under a pure oxygen atmosphere at 500℃ for 6 hours, heated to 850℃ at 5℃ / min and held for 12 hours, and then cooled to room temperature before being removed and ground to obtain an NCM613 powder sample containing 5% Al doping.

[0096] Except for adjusting the type of positive electrode active material to the positive electrode active material prepared above, everything else is the same as in Example 1-1.

[0097] Examples 3-5

[0098] <Preparation of Positive Electrode Active Materials>

[0099] According to the chemical formula LiNi 0.6 Co 0.1 Mn 0.3 O2 will react with the hydroxide precursor Ni 0.6 Co 0.1 Mn 0.3 After thoroughly mixing (OH)2 and Li2CO3 (Li: transition metal molar ratio of 1.05, transition metal elements being Ni, Co, and Mn), ZrO2 and TiO2 are added and mixed evenly to obtain a mixture, wherein the total mass ratio of Zr, Ti to Ni, Co, and Mn is 2:100 and 3:100, respectively. The resulting mixture is then placed in a tube furnace under a pure oxygen atmosphere at 500℃ for 6 hours, heated to 850℃ at 5℃ / min and held for 12 hours, and then cooled to room temperature before being removed and ground to obtain an NCM613 powder sample containing 2% Zr doping and 3% Ti doping.

[0100] Except for adjusting the type of positive electrode active material to the positive electrode active material prepared above, everything else is the same as in Example 1-1.

[0101] Examples 3-6

[0102] <Preparation of Positive Electrode Active Materials>

[0103] According to the chemical formula LiNi0.6 Co 0.1 Mn 0.3 O2 will react with the hydroxide precursor Ni 0.6 Co 0.1 Mn 0.3 After thoroughly mixing (OH)2 and Li2CO3 (Li: transition metal molar ratio of 1.05, the transition metal elements being Ni, Co, and Mn), Al2O3 is added and mixed evenly to obtain a mixture, wherein the total mass ratio of Al to Ni, Co, and Mn is 1:100. The resulting mixture is then placed in a tube furnace under a pure oxygen atmosphere at 500℃ for 6 hours, heated to 850℃ at 5℃ / min and held for 12 hours, and then cooled to room temperature before being removed and ground to obtain an NCM613 powder sample containing 1% Al doping.

[0104] Except for adjusting the type of positive electrode active material to the positive electrode active material prepared above, everything else is the same as in Example 1-1.

[0105] Examples 3-7

[0106] <Preparation of Positive Electrode Active Materials>

[0107] According to the chemical formula LiNi 0.6 Co 0.1 Mn 0.3 O2 will react with the hydroxide precursor Ni 0.6 Co 0.1 Mn 0.3 After thoroughly mixing (OH)2 and Li2CO3 (Li: transition metal molar ratio of 1.05, the transition metal elements being Ni, Co, and Mn), Al2O3 is added and mixed evenly to obtain a mixture in which the total mass ratio of Al to Ni, Co, and Mn is 9:100. The resulting mixture is then placed in a tube furnace under a pure oxygen atmosphere at 500℃ for 6 hours, heated to 850℃ at 5℃ / min and held for 12 hours, and then cooled to room temperature before being removed and ground to obtain an NCM613 powder sample containing 9% Al doping.

[0108] Except for adjusting the type of positive electrode active material to the positive electrode active material prepared above, everything else is the same as in Example 1-1.

[0109] Comparative Example 1 and Comparative Example 2

[0110] Except for adjusting the coating weight D of the negative electrode material layer according to Table 1, the rest is the same as in Example 1-1.

[0111] Comparative Examples 3 to 6

[0112] Except for the mass content W1 of the compound according to formula (I) and / or the mass content W2 of fluoroethylene carbonate according to Table 1, the rest is the same as in Examples 1-1.

[0113] When the mass content of compound (I) W1 and / or the mass content of fluoroethylene carbonate W2 changes, the mass content of lithium salt remains unchanged, while the mass content of solvent changes accordingly. The sum of the mass contents of compound (I), fluoroethylene carbonate, lithium salt and solvent is 100%.

[0114] The preparation and performance parameters of each embodiment and comparative example are shown in Tables 1 to 3.

[0115] Table 1

[0116] Note: In Table 1, "\" indicates that there is no corresponding parameter.

[0117] As can be seen from Examples 1-1 to 1-25 and Comparative Examples 1 to 6, the non-aqueous electrolyte secondary batteries of this application, by selecting an electrolyte containing compound (I) and fluoroethylene carbonate, and adjusting the mass content W1 of compound (I), the mass content W2 of fluoroethylene carbonate, and the coating weight D of the negative electrode material layer to satisfy: 0.2≤(W1+W2) / D≤100, 0.10≤D≤0.18, result in a higher number of cycle times, indicating a longer cycle life. In contrast, the secondary batteries of the comparative examples, whose coating weight D of the negative electrode material layer is not within the range of this application, whose electrolyte does not contain compound (I) or fluoroethylene carbonate, or whose mass content W1 of compound (I), the mass content W2 of fluoroethylene carbonate, and the coating weight D of the negative electrode material layer do not satisfy 0.2≤(W1+W2) / D≤100, have fewer cycle times, indicating a shorter cycle life.

[0118] The coating weight D of the negative electrode material layer typically affects the cycle life of a secondary battery. As can be seen from Examples 1-1 to 1-5, Comparative Example 1 and Comparative Example 2, secondary batteries with a coating weight D of the negative electrode material layer within the scope of this application have a higher number of cycles, indicating that the secondary battery has a longer cycle life.

[0119] The relationship between the mass content W1 of compound (I), the mass content W2 of fluoroethylene carbonate, and the coating weight D of the negative electrode material layer, expressed as (W1+W2) / D, typically affects the cycle life of the secondary battery. As can be seen from Examples 1-1 to 1-25, Comparative Examples 3 and 4, secondary batteries using the relationship between the mass content W1 of compound (I), the mass content W2 of fluoroethylene carbonate, and the coating weight D of the negative electrode material layer, expressed as (W1+W2) / D, have a higher number of cycle cycles, indicating a longer cycle life.

[0120] The relationship between the mass content W1 of compound (I) and the mass content W2 of fluoroethylene carbonate, expressed as W1 / W2, typically affects the cycle life of a secondary battery. As can be seen from Examples 1-1, 1-6 to 1-25, secondary batteries using the relationship between the mass content W1 of compound (I) and the mass content W2 of fluoroethylene carbonate, expressed as W1 / W2, fall within the scope of this application, exhibit a higher number of cycle cycles, indicating a longer cycle life.

[0121] The mass content W1 of compound (I) typically affects the cycle life of a secondary battery. As can be seen from Examples 1-1, 1-8, 1-10 to 1-15, secondary batteries using compound (I) with a mass content W1 within the scope of this application have a higher number of cycles, indicating a longer cycle life.

[0122] The mass content of fluoroethylene carbonate, W2, typically affects the cycle life of a secondary battery. As can be seen from Examples 1-1, 1-16 to 1-21, secondary batteries with a fluoroethylene carbonate mass content W2 within the scope of this application exhibit a higher number of cycles, indicating a longer cycle life.

[0123] The type of compound of formula (I) typically affects the cycle life of secondary batteries. From Examples 1-1, 1-26 to...

[0124] Examples 1-29 show that secondary batteries with a mass content W1 of compound (I) within the scope of this application have a higher number of cycles, indicating that the secondary batteries have a longer cycle life.

[0125] Table 2

[0126] The average particle size Dv50 of the negative electrode active material and its ratio D×Dv50 to the coating weight D of the negative electrode material layer typically affect the cycle life of a secondary battery. As can be seen from Examples 1-1, 2-1 to 2-9, secondary batteries using an average particle size Dv50 of the negative electrode active material and a ratio D×Dv50 within the scope of this application exhibit a higher number of cycle cycles, indicating a longer cycle life.

[0127] Table 3

[0128] Note: In Table 3, "\" indicates that there is no corresponding parameter.

[0129] The type of positive electrode active material usually affects the cycle life of a secondary battery. As can be seen from Examples 1-1, 3-1 to 3-3, the secondary batteries using positive electrode active materials within the scope of this application have a higher number of cycles, indicating that the secondary batteries have a longer cycle life.

[0130] When the positive electrode active material includes other doped coating elements, the type and content of these other doped coating elements usually affect the cycle life of the secondary battery. As can be seen from Examples 1-1, 3-4 to 3-7, secondary batteries using other doped coating elements within the scope of this application have a higher number of cycle cycles, indicating a longer cycle life.

[0131] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article.

[0132] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0133] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A non-aqueous electrolyte secondary battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode comprises a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the coating weight of the negative electrode material layer being D g / 1540.25 mm. 2 ; The electrolyte comprises fluoroethylene carbonate and a compound of formula (I): in, R1, R2, R3, R4, R5 and R6 are each independently selected from fluorine atoms, unsubstituted or fluorine-substituted C1 to C3 alkyl groups, and at least one of R1, R2, R3, R4, R5 and R6 is selected from fluorine atoms. Based on the mass of the electrolyte, the mass content of the compound of formula (I) is W1%, and the mass content of the fluoroethylene carbonate is W2%. D, W1, and W2 satisfy: 0.2≤(W1+W2) / D≤100, 0.10≤D≤0.

18.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein, 0.01≤W1≤10, and / or, 0.01≤W2≤5.

3. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, 0.1≤W1 / W2≤100.

4. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, The non-aqueous electrolyte secondary battery includes at least one of the following features: (1) 0.5 ≤ (W1 + W2) / D ≤ 50; (2)0.11≤D≤0.16； (3)0.5≤W1≤5； (4)0.1≤W2≤1； (5) 0.5 ≤ W1 / W2 ≤ 30.

5. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein, The compound of formula (I) includes at least one of the following compounds:

6. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The average particle size of the negative electrode active material is Dv50μm, and Dv50 and D satisfy: 0.8≤D×Dv50≤3.

4.

7. The non-aqueous electrolyte secondary battery according to claim 6, wherein, 5≤Dv50≤25.

8. The non-aqueous electrolyte secondary battery according to claim 6 or 7, wherein, 7≤Dv50≤15.

9. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector. The positive electrode material layer includes a positive electrode active material, which is a nickel-cobalt-manganese ternary material. Based on the total molar amount of the three elements nickel, cobalt, and manganese, the molar content of nickel is M3%, and M3≥50. The positive electrode active material also includes other doping elements, which include at least one of Al, Ta, Zr, B, Ti or Y. Based on the total mass of the three elements nickel, cobalt and manganese, the mass content of the other doping elements is W4%, where 0 ≤ W4 < 10.

10. An electronic device, wherein, The electronic device includes a non-aqueous electrolyte secondary battery as described in any one of claims 1 to 9.

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