Non-aqueous electrolyte secondary battery and electronic apparatus

Abstract

Provided are a non-aqueous electrolyte secondary battery and an electronic apparatus. The non-aqueous electrolyte secondary battery comprises a positive electrode sheet and an electrolyte, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. The thickness of the positive electrode active material layer is T μm. The electrolyte solution comprises a compound represented by formula (I). Based on of the mass of the electrolyte, the mass percentage content of the compound represented by formula (I) is W1%. T and W1 satisfy the expressions: 20≤T≤70, 0.01≤W1≤0.5, and 0.0005≤W1 / T≤0.02. By means of the described configuration, the non-aqueous electrolyte secondary battery has a low deformation rate.

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. To better meet market demands and achieve higher energy density in secondary batteries, existing technologies often increase the coating weight of the positive and negative electrode active materials or use thinner current collectors.

[0003] However, in existing secondary batteries, the positive and negative electrode active materials stretch during the lithium insertion / extraction process, leading to battery deformation, accelerated capacity decay, and even safety issues. Therefore, improving the deformation problem of secondary batteries has become a pressing technical challenge 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 improve the deformation problem of non-aqueous electrolyte secondary batteries.

[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 and an electrolyte. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the thickness of which is T μm. The electrolyte comprises a compound of formula (I):

[0007] Among them, R 11 R 12 R 13 and R 14 Each group is independently selected from hydrogen atoms, halogen atoms, cyano groups, phenyl groups, substituted or unsubstituted C1 to C10 alkyl groups, substituted or unsubstituted C2 to C10 alkenyl groups, substituted or unsubstituted C2 to C10 alkynyl groups, and substituted or unsubstituted C2 to C10 functional groups containing Si or O; when substituted, the substituent is a halogen atom; R 11 R 12 R 13 and R 14Two adjacent groups in R can connect to form a ring; 11 R 12 R 13 and R 14 At least one of the components contains an unsaturated bond; the mass percentage of compound (I) is W1% based on the mass of the electrolyte; T and W1 satisfy: 20≤T≤70, 0.01≤W1≤0.5, 0.0005≤W1 / T≤0.02. The non-aqueous electrolyte secondary battery provided by the first aspect of this application, by controlling the thickness T of the positive electrode active material layer in the positive electrode sheet within the range of this application, introducing compound (I) into the electrolyte and controlling the mass percentage W1% of compound (I) within the range of this application, and controlling the value of W1 / T within the range of this application, enables the positive electrode sheet and the electrolyte to play a synergistic role. Compound (I) polymerizes on the surface of the positive electrode sheet to form a film rich in organic components, uniform and dense interfacial electrolyte interfacial film (CEI film), so that the positive electrode active material layer of the positive electrode sheet and the separator have good adhesion, thereby suppressing the deformation problem caused by the extension of the positive electrode sheet during the charge and discharge cycle of the secondary battery. The CEI film formed on the surface of the positive electrode also has low impedance. The CEI film increases the probability of polarization of the secondary battery, reduces the probability of lithium plating in the secondary battery, and slows down the cycle decay of the secondary battery, thus exhibiting good cycle performance.

[0008] In one embodiment of this application, the non-aqueous electrolyte secondary battery satisfies at least one of the following characteristics: (1) 30≤T≤60; (2) 0.05≤W1≤0.15; (3) 0.001≤W1 / T≤0.01. With the above settings, the secondary battery exhibits a small deformation rate and good cycle performance.

[0009] In one embodiment of this application, the compound of formula (I) includes at least one of tetramethyldivinyldisiloxane, bis(trimethylsilane) maleate, tetraallylsilane, pentamethylpentavinylcyclopentasiloxane, vinyltrimethylsilane, divinyldimethylsilane, 1,3-dimethyl-1,1,3,3-tetraethylenedisiloxane, trivinylmethylsilane, triethylsilylacetylene, tetravinylsilane, tetramethyltetravinylcyclotetrasiloxane, diphenyldifluorosilane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, or vinyltriethoxysilane. Using compounds of formula (I) of the above types is beneficial for suppressing deformation problems caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery, and also helps to reduce the probability of lithium plating in the secondary battery, thus slowing down the cycle degradation of the secondary battery, and exhibiting good cycle performance.

[0010] In one embodiment of this application, the electrolyte further includes a sulfur-oxygen double bond compound, the mass percentage of which is W2% based on the mass of the electrolyte; W1 and W2 satisfy: 0.5≤W2≤5, 0.01≤W1 / W2≤0.1, 1≤W1+W2≤5.2. When the sulfur-oxygen double bond compound is introduced into the electrolyte, it can form a film composed of inorganic components on the surface of the positive electrode. By introducing the sulfur-oxygen double bond compound into the electrolyte and ensuring that its content and its relationship with the content of the compound of formula (I) satisfy the above-mentioned relationship and numerical range, deformation caused by the stretching of the positive electrode during the charge-discharge cycle of the secondary battery can be suppressed. Furthermore, the CEI film increases the probability of secondary battery polarization, reduces the probability of lithium plating in the secondary battery, and slows down the cycle decay of the secondary battery, resulting in good cycle performance.

[0011] In one embodiment of this application, the non-aqueous electrolyte secondary battery satisfies at least one of the following characteristics: (i) 1 ≤ W2 ≤ 3; (ii) 0.02 ≤ W1 / W2 ≤ 0.05; (iii) 1.2 ≤ W1 + W2 ≤ 3.1. Through the above settings, deformation caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery can be further suppressed, the probability of lithium plating in the secondary battery is reduced, and the cycle degradation of the secondary battery is slowed down, resulting in good cycle performance.

[0012] In one embodiment of this application, the sulfur-oxygen double bond compound includes at least one selected from 1,3-propanesulfonyl lactone, vinyl sulfate, propenesulfonyl lactone, 3-fluoro-1,3-propanesulfonyl lactone, 1,2-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, 1,2-butanesulfonyl lactone, 1,3-butanesulfonyl lactone, 2,4-butanesulfonyl lactone, or 1,3-pentanesulfonyl lactone. Using the above-mentioned sulfur-oxygen double bond compounds is beneficial in suppressing deformation problems caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery, while ensuring good cycle performance.

[0013] In one embodiment of this application, the positive electrode active material layer includes a positive electrode active material, the particle size of which, Dv10μm and Dv50μm, satisfy the following values: 0.5≤Dv10≤5, 1≤Dv50≤10, and 0.5≤Dv50 / Dv10≤5. Controlling the particle sizes Dv10, Dv50, and Dv50 / Dv10 within these ranges is beneficial for improving the adhesion between the positive electrode active material layer and the separator, thereby suppressing deformation caused by the elongation of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The uniform distribution of positive electrode active material particles in the positive electrode active material layer also helps to improve the lithium-ion transport rate, thereby improving the cycle performance of the secondary battery.

[0014] In one embodiment of this application, the non-aqueous electrolyte secondary battery satisfies: 1.1 ≤ (W1 + W2) × (Dv50 / Dv10) ≤ 20. By controlling the value of (W1 + W2) × (Dv50 / Dv10) within the above range, the secondary battery exhibits good cycle performance, and the deformation problem caused by the extension of the positive electrode sheet during charge-discharge cycles can also be improved.

[0015] In one embodiment of this application, the non-aqueous electrolyte secondary battery satisfies at least one of the following characteristics: (a) 0.6 ≤ Dv10 ≤ 2; (b) 1.5 ≤ Dv50 ≤ 5; (c) 1.5 ≤ Dv50 / Dv10 ≤ 4; (d) 3 ≤ (W1 + W2) × (Dv50 / Dv10) ≤ 12. With the above settings, the secondary battery exhibits good cycle performance, and the deformation problem caused by the stretching of the positive electrode sheet during charge-discharge cycles can be further improved.

[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 and an electrolyte. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The thickness of the positive active material layer is T μm. The electrolyte includes a compound of formula (I). Based on the mass of the electrolyte, the mass percentage of the compound of formula (I) is W1%. T and W1 satisfy: 20≤T≤70, 0.01≤W1≤0.5, 0.0005≤W1 / T≤0.02. This application's non-aqueous electrolyte secondary battery achieves synergistic effects by controlling the thickness T of the positive electrode active material layer within the range specified in this application, introducing a compound of formula (I) into the electrolyte, controlling the mass percentage W1% of the compound of formula (I) within the range specified in this application, and controlling the value of W1 / T within the range specified in this application. This allows the positive electrode and electrolyte to work together synergistically. The compound of formula (I) polymerizes on the surface of the positive electrode to form a uniform and dense CEI film rich in organic components. This results in good adhesion between the positive electrode active material layer and the separator, thereby suppressing deformation caused by the stretching of the positive electrode during the charge-discharge cycle of the secondary battery. The CEI film formed on the surface of the positive electrode also has low impedance. The CEI film reduces the probability of increased polarization in the secondary battery, lowers the probability of lithium plating, and slows down the cycle degradation of the secondary battery, resulting in excellent cycle performance. Attached Figure Description

[0019] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0020] Figure 1 is a schematic cross-sectional view of the positive electrode sheet of one embodiment of this application along its thickness and width directions;

[0021] Figure 2 is a schematic cross-sectional view of the positive electrode sheet along its thickness and width directions according to another embodiment of this application.

[0022] Reference numerals: 100 - Positive electrode sheet; 10 - Positive current collector; 11 - Positive active material layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0024] 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.

[0025] The first aspect of this application provides a non-aqueous electrolyte secondary battery, comprising a positive electrode and an electrolyte. The positive electrode includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the thickness of which is T μm. The electrolyte comprises a compound of formula (I):

[0026] Among them, R 11 R 12 R 13 and R 14 Each group is independently selected from hydrogen atoms, halogen atoms, cyano groups, phenyl groups, substituted or unsubstituted C1 to C10 alkyl groups, substituted or unsubstituted C2 to C10 alkenyl groups, substituted or unsubstituted C2 to C10 alkynyl groups, and substituted or unsubstituted C2 to C10 functional groups containing Si or O; when substituted, the substituent is a halogen atom; R 11 R 12 R 13 and R 14 Two adjacent groups in R can connect to form a ring; 11 R 12 R 13 and R 14At least one of them contains an unsaturated bond. Based on the mass of the electrolyte, the mass percentage of compound (I) is W1%; T and W1 satisfy: 20≤T≤70, 0.01≤W1≤0.5, 0.0005≤W1 / T≤0.02.

[0027] For ease of understanding, in this application, the width direction of the positive electrode sheet is defined as Y, and its thickness direction as Z. It should be understood that the above definitions of direction are for the purpose of describing this application, and the directions defined in this application can be understood based on the relative positions of the elements in the accompanying drawings and actual products. Furthermore, the width and thickness directions of the positive current collector and the positive active material layer are the same as those of the separator. The phrase "positive active material layer disposed on at least one surface of the positive current collector" above means that the positive active material layer can be disposed on one or both surfaces of the positive current collector; "surface" refers to part or all of the surface of the positive current collector. As shown in Figure 1, the positive electrode sheet 100 includes a positive current collector 10 and a positive active material layer 11. The positive active material layer 11 is disposed on one surface of the positive current collector 10, and the thickness of the positive active material layer 11 is indicated by T. As shown in Figure 2, the positive electrode 100 includes a positive current collector 10 and a positive active material layer 11. The positive active material layer 11 is disposed on two surfaces of the positive current collector 10, and the thickness of the positive active material layer 11 is indicated by T. It should be noted that, in this application, "thickness of the positive active material layer" refers to the thickness of a single-layer positive active material layer after cold pressing during the preparation of the positive electrode.

[0028] For example, T can be 20, 25, 30, 35, 40, 42, 47, 50, 53, 56, 60, 62, 66, 70, or any value within any two of the above ranges. If T is less than 20, the thickness of the positive electrode active material layer is too small, resulting in insufficient positive electrode active material and insufficient capacity provided by the positive electrode sheet, which will affect the energy density of the secondary battery. If T is greater than 70, the thickness of the positive electrode active material layer is too large, making electrolyte wetting and transport difficult, which will increase the polarization of the secondary battery, affect the capacity utilization of the secondary battery, and cause a loss of energy density.

[0029] For example, W1 can be 0.01, 0.03, 0.05, 0.07, 0.1, 0.13, 0.18, 0.20, 0.22, 0.26, 0.3, 0.33, 0.35, 0.4, 0.42, 0.46, 0.5, or any value within any two of the above ranges. The compound of formula (I) can polymerize on the surface of the positive electrode to form an organic-rich interfacial electrolyte interfacial film (CEI film), enhancing the adhesion between the positive electrode active material layer and the separator, thereby suppressing deformation caused by the stretching of the positive electrode during the charge-discharge cycle of the secondary battery. If W1 is less than 0.01, the mass percentage of compound (I) is too small, and the function of compound (I) itself is difficult to exert; if W1 is greater than 0.5, the mass percentage of compound (I) is too large, and the CEI film formed on the surface of the positive electrode will be too thick, which will have a large impedance, increase the polarization of the secondary battery, and make the secondary battery prone to lithium plating, causing its cycle capacity to decay faster.

[0030] For example, the value of W1 / T is 0.0005, 0.001, 0.0015, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02, or any value between any two of the above ranges. When the W1 / T value is less than 0.0005, the probability of forming a uniform and dense CEI film on the surface of the positive electrode is low, and the adhesion between the positive active material layer of the positive electrode and the separator is poor. When the W1 / T value is greater than 0.02, the CEI film formed on the surface of the positive electrode will be too thick and have a large impedance, which will increase the polarization of the secondary battery and make the secondary battery more prone to lithium plating, resulting in accelerated decay of its cycle capacity.

[0031] The non-aqueous electrolyte secondary battery provided in the first aspect of this application achieves synergistic effects between the positive electrode and the electrolyte by controlling the thickness T of the positive electrode active material layer within the range specified in this application, introducing a compound of formula (I) into the electrolyte, controlling the mass percentage W1% of the compound of formula (I) within the range specified in this application, and controlling the value of W1 / T within the range specified in this application. The compound of formula (I) polymerizes on the surface of the positive electrode to form a uniform and dense CEI film rich in organic components, resulting in good adhesion between the positive electrode active material layer and the separator. This suppresses deformation caused by the stretching of the positive electrode during the charge-discharge cycle of the secondary battery. The CEI film formed on the surface of the positive electrode also has low impedance, reducing the probability of increased polarization in the secondary battery and decreasing the probability of lithium plating, thus slowing down the cycle degradation of the secondary battery and exhibiting good cycle performance.

[0032] In one embodiment of this application, C1 to C10 alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and their isomers; C2 to C10 alkenyl groups include, but are not limited to, ethylene, propylene, butene, n-pentene, n-hexene, n-heptene, n-octene, n-nonene, n-decyl, and their isomers; C2 to C10 alkynyl groups include, but are not limited to, acetylene, propyne, butyne, n-pentyne, n-hexyne, n-heptyne, n-octyne, n-nonyne, n-decyne, and their isomers; C2 to C10 functional groups containing Si or O include, but are not limited to, alkylalkenylsiloxane, alkylsiloxane, alkenylsiloxane, alkylsilane, alkenylsilane, alkylalkenylsilane, alkylalkynylsilane, ether, aldehyde, carbonyl, carboxyl, and ester groups; halogen atoms include fluorine (F) and bromine (Br).

[0033] This application does not impose any particular restrictions on the method of controlling the thickness of the positive electrode active material layer, as long as the purpose of this application can be achieved. For example, it can be achieved by adjusting the coating weight or cold pressing parameters. Generally speaking, the greater the coating weight, or the smaller the cold pressing pressure and the greater the cold pressing speed, the thicker the layer; the smaller the coating weight, or the larger the cold pressing pressure and the smaller the cold pressing speed, the thinner the layer.

[0034] In one embodiment of this application, 30 ≤ T ≤ 60. In another embodiment of this application, 0.05 ≤ W1 ≤ 0.15. In yet another embodiment of this application, 0.001 ≤ W1 / T ≤ 0.01. In yet another embodiment of this application, 30 ≤ T ≤ 60; 0.05 ≤ W1 ≤ 0.15. In yet another embodiment of this application, 0.05 ≤ W1 ≤ 0.15; 0.001 ≤ W1 / T ≤ 0.01. In yet another embodiment of this application, 30 ≤ T ≤ 60; 0.001 ≤ W1 / T ≤ 0.01. In yet another embodiment of this application, 30 ≤ T ≤ 60; 0.05 ≤ W1 ≤ 0.15; 0.001 ≤ W1 / T ≤ 0.01. For example, T is 30, 35, 37, 40, 42, 47, 50, 53, 56, 58, 60, or any value between any two of the above ranges. W1 is 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, or any value between any two of the above ranges. The value of W1 / T is 0.001, 0.0015, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, or any value between any two of the above ranges. Controlling at least one of the thickness T of the positive electrode active material layer, the mass percentage W1% of the compound of formula (I), or the value of W1 / T within the above range is beneficial for the polymerization of a uniform and dense CEI film on the surface of the positive electrode sheet, enhancing the adhesion between the positive electrode active material layer and the separator, thereby further suppressing the deformation problem caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The CEI film formed on the surface of the positive electrode sheet also has low impedance. The CEI film increases the probability of polarization in the secondary battery, reduces the probability of lithium plating in the secondary battery, and slows down the cycle decay of the secondary battery, resulting in good cycle performance.

[0035] In one embodiment of this application, the compound of formula (I) includes at least one of tetramethyldivinyldisiloxane, bis(trimethylsilane) maleate, tetraallylsilane, pentamethylpentavinylcyclopentasiloxane, vinyltrimethylsilane, divinyldimethylsilane, 1,3-dimethyl-1,1,3,3-tetraethylenedisiloxane, trivinylmethylsilane, triethylsilylacetylene, tetravinylsilane, tetramethyltetravinylcyclotetrasiloxane, diphenyldifluorosilane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, or vinyltriethoxysilane. Using compounds of formula (I) of the above types is beneficial for polymerizing a uniform and dense CEI film on the positive electrode sheet, enhancing the adhesion between the positive electrode active material layer and the separator, thereby suppressing deformation problems caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The CEI film formed on the surface of the positive electrode also has low impedance. The CEI film increases the probability of polarization of the secondary battery, reduces the probability of lithium plating in the secondary battery, and slows down the cycle decay of the secondary battery, thus exhibiting good cycle performance.

[0036] In one embodiment of this application, the electrolyte further includes a sulfur-oxygen double bond compound, the mass percentage of which is W2% based on the mass of the electrolyte; W1 and W2 satisfy: 0.5≤W2≤5, 0.01≤W1 / W2≤0.1, 1≤W1+W2≤5.2. For example, W2 is 0.5, 1, 1.3, 1.7, 2.1, 2.5, 3.0, 3.3, 3.7, 4.0, 4.2, 4.6, 5.0, or any value between any two of the above ranges. For example, the value of W1 / W2 is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, or any value between any two of the above ranges. For example, the value of W1+W2 can be 1, 1.2, 1.7, 2, 2.2, 2.7, 3.1, 3.3, 3.6, 4, 4.1, 4.3, 4.6, 4.7, 5.0, 5.2, or any value within any two of the above ranges. When a sulfur-oxygen double bond compound is introduced into the electrolyte, it can form a film composed of inorganic components on the surface of the positive electrode. By introducing sulfur-oxygen double bond compounds into the electrolyte and ensuring that the content of these compounds and their content in relation to the content of the compound in formula (I) satisfy the aforementioned relationship and numerical range, the ratio of organic and inorganic components in the positive electrode interface film can be controlled. This allows the positive electrode interface film to have suitable impedance, resulting in good adhesion between the positive electrode active material layer and the separator. This suppresses deformation caused by the stretching of the positive electrode during the charge-discharge cycle of the secondary battery. Furthermore, the CEI film reduces the probability of increased polarization in the secondary battery, decreases the probability of lithium plating, and slows down the cycle decay of the secondary battery, thus exhibiting good cycle performance.

[0037] In one embodiment of this application, the sulfur-oxygen double bond compound includes at least one of 1,3-propanesulfonyl lactone, vinyl sulfate, propenesulfonyl lactone, 3-fluoro-1,3-propanesulfonyl lactone, 1,2-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, 1,2-butanesulfonyl lactone, 1,3-butanesulfonyl lactone, 2,4-butanesulfonyl lactone, or 1,3-pentanesulfonyl lactone. Selecting the above-mentioned sulfur-oxygen double bond compounds is beneficial for forming an interface film with inorganic components on the surface of the positive electrode sheet. This ensures a suitable ratio of organic to inorganic components in the interface film, which, under appropriate impedance, facilitates good adhesion between the positive electrode active material layer and the separator. This, in turn, helps to suppress deformation problems caused by the stretching of the positive electrode sheet during the charge-discharge cycle of the secondary battery, while maintaining good cycle performance.

[0038] In one embodiment of this application, 1 ≤ W2 ≤ 3. In another embodiment of this application, 0.02 ≤ W1 / W2 ≤ 0.05. In yet another embodiment of this application, 1.2 ≤ W1 + W2 ≤ 3.1. In yet another embodiment of this application, 1 ≤ W2 ≤ 3; 0.02 ≤ W1 / W2 ≤ 0.05. In yet another embodiment of this application, 1 ≤ W2 ≤ 3; 1.2 ≤ W1 + W2 ≤ 3.1. In yet another embodiment of this application, 0.02 ≤ W1 / W2 ≤ 0.05; 1.2 ≤ W1 + W2 ≤ 3.1. In yet another embodiment of this application, 1 ≤ W2 ≤ 3; 0.02 ≤ W1 / W2 ≤ 0.05; 1.2 ≤ W1 + W2 ≤ 3.1. For example, W2 is 1, 1.3, 1.5, 1.7, 1.9, 2.1, 2.3, 2.5, 2.7, 3.0, or any value within any two of the above ranges. For example, the value of W1 / W2 is 0.02, 0.03, 0.04, 0.05, or any value within any two of the above ranges. For example, the value of W1+W2 is 1.2, 1.5, 1.7, 1.8, 2, 2.2, 2.5, 2.7, 2.9, 3.1, or any value within any two of the above ranges. Controlling the values ​​of W2, W1+W2, and W1 / W2 within the aforementioned ranges is beneficial for forming an interface film with a suitable ratio of organic and inorganic components on the surface of the positive electrode. When the interface film of the positive electrode has a suitable impedance, there is good adhesion between the positive active material layer of the positive electrode and the separator. This can further suppress the deformation problem caused by the extension of the positive electrode during the charge and discharge cycle of the secondary battery. In addition, the CEI film increases the probability of polarization of the secondary battery, reduces the probability of lithium plating in the secondary battery, and slows down the cycle decay of the secondary battery, thus exhibiting good cycle performance.

[0039] In one embodiment of this application, the positive electrode active material layer includes a positive electrode active material, wherein the particle size of the positive electrode active material, Dv10μm and Dv50μm, satisfies the following conditions: 0.5≤Dv10≤5, 1≤Dv50≤10, and 1.1≤Dv50 / Dv10≤5. For example, Dv10 is 0.5, 0.6, 1, 1.3, 1.7, 2, 2.2, 2.7, 3, 3.5, 4, 4.3, 5, or any value between any two of the above ranges. Dv50 is 1, 1.5, 2, 2.3, 3, 3.6, 4, 4.5, 5, 5.6, 6, 6.2, 7, 7.4, 8, 8.8, 9, 9.6, 10, or any value between any two of the above ranges. The values ​​of Dv50 / Dv10 are 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, or any value within any two of the above ranges. Controlling the particle sizes Dv10, Dv50, and Dv50 / Dv10 of the positive electrode active material within these ranges helps to ensure that the particle sizes of the positive electrode active material are well-matched. Smaller particles are embedded in the gaps formed by larger particles, resulting in a uniform distribution of the positive electrode active material particles within the positive electrode active material layer. This improves the adhesion between the positive electrode active material layer and the separator, thereby suppressing deformation caused by the elongation of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The uniform distribution of positive electrode active material particles within the positive electrode active material layer also helps to improve the lithium-ion transport rate, thus enhancing the cycle performance of the secondary battery.

[0040] This application does not impose any particular limitation on the type of positive electrode active material, as long as it can achieve the purpose of this application. For example, the positive electrode active material may include, but is not limited to, at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, lithium manganese iron phosphate, or lithium titanate.

[0041] In this application, "particle size Dv10 of the positive electrode active material" refers to the particle size that, in the volume-based particle size distribution, reaches 10% of the total volume from the smallest particle size side. "Particle size Dv50 of the positive electrode active material" refers to the particle size that, in the volume-based particle size distribution, reaches 50% of the total volume from the smallest particle size side.

[0042] This application does not impose any particular restrictions on the method of controlling the particle size of the positive electrode active material, as long as the purpose of this application can be achieved. For example, it can be achieved through crushing, grinding, ball milling, sieving, etc.

[0043] In one embodiment of this application, the non-aqueous electrolyte secondary battery satisfies: 1.1 ≤ (W1+W2)×(Dv50 / Dv10) ≤ 20. For example, the value of (W1+W2)×(Dv50 / Dv10) is 1.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any value between any two of the above ranges. Adjusting the value of (W1+W2)×(Dv50 / Dv10) within the above range is beneficial for the electrolyte containing the compound of formula (I) and the sulfur-oxygen double bond compound to exert a synergistic effect with the positive electrode, and for the formation of an interfacial film containing a suitable proportion of inorganic and organic components on the surface of the positive electrode. This interfacial film has suitable impedance, and the positive electrode active material layer of the positive electrode has good adhesion to the separator. In this way, the secondary battery has good cycle performance, and the deformation problem caused by the extension of the positive electrode sheet during the charge and discharge cycle can also be improved.

[0044] In one embodiment of this application, 0.6 ≤ Dv10 ≤ 2. For example, Dv10 is 0.6, 0.8, 1, 1.1, 1.3, 1.5, 1.7, 1.8, 2, or any value within any two of the above ranges. Controlling the particle size Dv10 of the positive electrode active material within the above range facilitates the embedding of smaller particles into the gaps formed by larger particles, resulting in a uniform distribution of the positive electrode active material particles within the positive electrode active material layer. This improves the adhesion between the positive electrode active material layer and the separator, thereby further suppressing deformation caused by the elongation of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The uniform distribution of positive electrode active material particles within the positive electrode active material layer also helps to increase the lithium-ion transport rate, thereby improving the cycle performance of the secondary battery.

[0045] In one embodiment of this application, 1.5 ≤ Dv50 ≤ 5. For example, Dv50 is 1.5, 2, 2.3, 3, 3.6, 4, 4.5, 5, or any value between any two of the above ranges. Controlling the particle size Dv50 of the positive electrode active material within the above range helps reduce the probability of agglomeration of the positive electrode active material particles. Smaller particles of positive electrode active material are embedded in the gaps formed by larger particles, resulting in a uniform distribution of the positive electrode active material particles within the positive electrode active material layer. This improves the adhesion between the positive electrode active material layer and the separator, thereby further suppressing deformation caused by the elongation of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The uniform distribution of positive electrode active material particles within the positive electrode active material layer also helps improve the lithium-ion transport rate, thereby improving the cycle performance of the secondary battery.

[0046] In one embodiment of this application, 1.5 ≤ Dv50 / Dv10 ≤ 4. For example, the value of Dv50 / Dv10 is 1.5, 1.7, 2, 2.2, 2.5, 2.7, 3, 3.2, 3.5, 3.8, 4, or any value between any two of the above ranges. Controlling the value of Dv50 / Dv10 within the above range helps to ensure that the particle sizes of the positive electrode active material are matched, with smaller particles embedded in the gaps formed by larger particles, resulting in a uniform distribution of positive electrode active material particles within the positive electrode active material layer. This improves the adhesion between the positive electrode active material layer and the separator, thereby further suppressing deformation caused by the elongation of the positive electrode sheet during the charge-discharge cycle of the secondary battery. The uniform distribution of positive electrode active material particles within the positive electrode active material layer also helps to improve the lithium-ion transport rate, thereby improving the cycle performance of the secondary battery.

[0047] In one embodiment of this application, 3 ≤ (W1+W2)×(Dv50 / Dv10) ≤ 12. For example, the value of (W1+W2)×(Dv50 / Dv10) is 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or any value between any two of the above ranges. Controlling the value of (W1+W2)×(Dv50 / Dv10) within the above range is beneficial for the electrolyte containing the compound of formula (I) and the sulfur-oxygen double bond compound to exert a synergistic effect with the positive electrode sheet. It is also beneficial for forming an interfacial film containing an appropriate proportion of inorganic and organic components on the surface of the positive electrode sheet. This interfacial film has suitable impedance, and there is good adhesion between the positive electrode active material layer of the positive electrode sheet and the separator. Thus, the secondary battery has good cycle performance, and the deformation problem caused by the stretching of the positive electrode sheet during charge-discharge cycles can be further improved.

[0048] In one embodiment of this application, the electrolyte further includes an organic solvent and a lithium salt. This application does not particularly limit the types of organic solvents and lithium salts; those skilled in the art can select organic solvents and lithium salts known in the art according to actual needs, as long as the purpose of this application can be achieved. For example, the organic solvent includes, but is not limited to, at least one of carbonate compounds, carboxylic acid ester compounds, ether compounds, or other organic solvents. The aforementioned carbonate compounds 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). Fluorocarbonate 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 compounds 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, or caprolactone. The aforementioned ether compounds may include, but are not limited to, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. Other organic solvents may include, but are not limited to, at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolium ketone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, or phosphate esters. Lithium salts include, but are 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(oxalate-borate), or lithium di(fluorooxalate-borate). This application does not impose any particular limitation on the content of organic solvents and lithium salts, as long as the purpose of this application is achieved. For example, based on the mass of the electrolyte, the organic solvent content is 78.5% to 91.49% by mass, and the lithium salt content is 8% to 16% by mass.

[0049] The present application has no particular limitation on the positive electrode current collector, as long as the object of the present application can be achieved. For example, the positive electrode current collector may comprise aluminum foil or aluminum alloy foil, etc. In the present application, there is no particular limitation on the thickness of the positive electrode current collector, as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm. In one embodiment, the positive electrode active 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 active material layer, as long as the object 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 active material layer, which can be selected by those skilled in the art according to actual needs, as long as the object 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 active material layer is (97~97.9):(0.8~1.7):(1.0~2.0).

[0050] In one embodiment of the present application, the non-aqueous electrolyte secondary battery further comprises a negative electrode plate. The present application has no particular limitation on the negative electrode plate, as long as the object of the present application can be achieved. In one embodiment, the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is disposed on one surface or two surfaces of the negative electrode current collector, and the above-mentioned "surface" may be a partial surface of the negative electrode current collector, or may be the entire surface of the negative electrode current collector. The present application has no particular limitation on the negative electrode current collector, as long as the object 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, etc. The negative electrode active 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 object 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 12The negative electrode active material layer contains at least one of the following: Li-Al alloy or metallic lithium. In this application, there are no particular limitations on the thickness of the negative electrode current collector or the negative electrode active material layer, as long as the purpose of this application is achieved. For example, the thickness of the negative electrode current collector is 6 μm to 10 μm, and the thickness of the negative electrode active material layer is 30 μm to 130 μm. Optionally, the negative electrode active material layer may further include at least one of the following: a negative electrode conductive agent, a thickener, or a negative electrode binder. This application does not particularly limit the types of negative electrode conductive agents, thickeners, and negative electrode binders in the negative electrode active material layer, as long as the purpose of this application is achieved. This application does not particularly limit the mass ratio of the negative electrode active material, negative electrode conductive agent, thickener, and negative electrode binder in the negative electrode active material layer, as long as the purpose of this application is achieved. For example, the mass ratio of the negative electrode active material, negative electrode conductive agent, thickener, and negative electrode binder in the negative electrode active material layer is (95–98):(0–1.5):(0–3):(1–2).

[0051] In one embodiment of this application, the non-aqueous electrolyte secondary battery further includes a separator disposed between the positive electrode and the negative electrode. The separator separates the positive and negative electrode, preventing internal short circuits in the secondary battery, allowing electrolyte ions to pass freely, and does not affect the electrochemical charge-discharge process. This application does not impose any particular limitation on the separator, as long as it achieves the purpose of this application. For example, the separator 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 separator type 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 separator thickness, as long as it achieves the purpose of this application.

[0052] In one embodiment of this application, the non-aqueous electrolyte secondary battery further 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.

[0053] The secondary battery described in this application is not particularly limited and may include any device in which an electrochemical reaction occurs. For example, a secondary battery may include, but is not limited to, a lithium metal secondary battery, a lithium-ion secondary battery (lithium-ion battery), a lithium polymer secondary battery, or a lithium-ion polymer secondary battery.

[0054] This application does not impose any particular limitation on the preparation method of the secondary battery. Any preparation method known in the art can be used, as long as it can achieve the purpose of this application. For example, the preparation method of the secondary battery includes, but is not limited to, the following steps: stacking the separator, positive electrode, separator and negative electrode in sequence, and winding, folding or 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 the separator, positive electrode, separator and negative electrode in sequence, and 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.

[0055] 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.

[0056] 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.

[0057] Example

[0058] 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.

[0059] Test methods and equipment:

[0060] Testing of the thickness of the positive electrode active material layer:

[0061] The lithium-ion battery was discharged to 3.0V at 0.5C and then disassembled to obtain the positive electrode sheet. It was then cleaned by soaking in high-purity anhydrous DMC for 8 hours. After cleaning three times, it was left to stand in a vacuum drying oven for 12 hours. The positive electrode sheet was then sliced ​​to obtain a clear cross-section, and the thickness of the positive electrode active material layer was measured using a scanning electron microscope.

[0062] Testing of the particle size of the positive electrode active material:

[0063] The particle sizes Dv10 and Dv50 of the positive electrode active material were determined using a laser particle size analyzer.

[0064] Test of the adhesion between the positive electrode and the separator:

[0065] The adhesion between the separator and the positive electrode was measured using a 180° peel test. The lithium-ion batteries in the tested examples and comparative examples were discharged to 3V at 0.5C and then disassembled. The negative electrode was peeled off, and the separator and positive electrode were soaked in dimethyl carbonate for 20 minutes to remove the electrolyte. The separator and positive electrode were then cut into 54.2mm × 72.5mm samples. The separator and positive electrode were then laminated using a hot press at 85°C, 1MPa, and 85s. The laminated samples were then cut into 15mm × 54.2mm strips to obtain test strips for testing the adhesion between the separator and the positive electrode. A 15mm × 55mm double-sided adhesive tape (NITTO.NO5000NS) was attached to a steel plate, and the test strips were then attached to the tape with the test side facing down. A 15mm × 70mm paper strip is attached to one end of a test strip using double-sided tape. A 2kg roller is manually pushed across the test strip eight times to obtain the test sample. A tensile testing machine is then used. The test sample is fixed on the test table, the paper strip is folded upwards 180° and secured with clamps. The tensile testing machine is then used to pull the paper strip at a speed of 50mm / min until the diaphragm and positive electrode separate from the double-sided tape surface. The test data is then saved. The adhesive force F1 between the diaphragm and the positive electrode is calculated based on the tensile force and displacement during separation, expressed in N / m.

[0066] 25℃ Cyclic Test:

[0067] 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. The lithium-ion battery was subjected to multiple cycles under the above conditions, and the discharge capacity was measured for each cycle. The initial discharge capacity was taken as 100%, and the charge-discharge cycles were repeated until the discharge capacity retention rate decreased to 80% of the initial discharge capacity. The test was then stopped, and the number of cycles was recorded as an indicator of the lithium-ion battery's capacity retention rate at room temperature. Capacity retention rate = (Capacity after each discharge cycle / Initial discharge capacity) × 100%.

[0068] Deformation rate test:

[0069] At 45℃, the lithium-ion battery was charged at a constant current of 0.5C to 4.4V, 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, marking the first cycle. After 10 cycles under the above conditions, the lithium-ion battery was charged at a constant current of 0.5C to 4.4V, then charged at a constant voltage of 4.4V to a current of 0.05C. The thickness of the lithium-ion battery was then measured using a PPG thickness gauge and a micrometer, with thickness values ​​Q1 and Q2 respectively. The deformation rate was calculated as follows: Deformation rate = (Q1 - Q2) / Q2 × 100%.

[0070] Example 1-1

[0071] <Preparation of Electrolyte>

[0072] In an argon-atmospheric glove box with a water content of <10 ppm, ethylene carbonate, propylene carbonate, and diethyl carbonate were mixed in a mass ratio of 1:1:2 to obtain an organic solvent. Then, compound (I) and lithium salt LiPF6 were added to the organic solvent, and the mixture was stirred until homogeneous to obtain an electrolyte. The mass percentage (W1%) of compound (I) based on the mass of the electrolyte is shown in Table 1, the mass percentage of lithium salt LiPF6 is 12%, and the remainder is organic solvent. The types of compound (I) are shown in Table 1.

[0073] <Preparation of the positive electrode>

[0074] Nickel-cobalt-manganese ternary materials (LiNi) 0.5 Co 0.2 Mn 0.3 O2), positive electrode conductive agent conductive carbon black (Super P), 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 97:1.4:1.6, 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 72 wt% was obtained. The positive electrode slurry was uniformly coated onto one surface of a 6 μm thick aluminum foil used as a positive electrode current collector, and dried at 85°C to obtain a positive electrode sheet with a single-sided coating of the positive electrode active material layer. 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 the positive electrode active material layer. After cold pressing and slitting, positive electrode sheets with dimensions of 74 mm × 867 mm were obtained for later use. The single-layer thickness T of the positive electrode active material layer is shown in Table 1.

[0075] <Preparation of Negative Electrode Sheets>

[0076] Artificial graphite as the negative electrode active material and styrene-butadiene rubber (SBR) as the negative electrode binder (weight average molecular weight 5×10⁻⁶) are used. 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, and the copper foil was dried at 85°C for 4 hours to obtain a negative electrode sheet with a single-sided coating of negative electrode active material. The above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided coating of negative electrode active material. After cold pressing, cutting, and slitting, a negative electrode sheet with a size of 76.6 mm × 875 mm was obtained.

[0077] <Preparation of the diaphragm>

[0078] 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. 2 Then, 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.

[0079] <Preparation of Lithium-ion Batteries>

[0080] The prepared separator, positive electrode, and negative electrode are stacked in sequence, with the side of the separator coated with the inorganic layer and polymer layer facing the positive electrode, and the side coated only with the polymer layer facing the negative electrode. This places the separator between the positive and negative electrodes to act as a separator. The electrode assembly is then wound to obtain the electrode assembly. The electrode assembly is then placed in an aluminum-plastic film packaging bag and dried in an 85°C vacuum oven for 12 hours to remove moisture. The electrolyte is then injected, and after vacuum sealing, settling, formation, and shaping processes, a lithium-ion battery is obtained.

[0081] Examples 1-2 to Examples 1-15

[0082] Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as in Example 1-1.

[0083] When the mass percentage W1% of compound (I) changes, the mass percentage of lithium salt remains unchanged, while the mass percentage of organic solvent changes accordingly. The sum of the mass percentages of compound (I), lithium salt, and organic solvent is 100%.

[0084] Examples 2-1 to 2-29

[0085] Except for the further introduction of sulfur-oxygen double bond compounds into the electrolyte and the adjustment of the relevant preparation parameters according to Table 2, the rest is the same as in Examples 1-1.

[0086] When the mass percentage of compound (I) and / or sulfur-oxygen double bond compound changes, the mass percentage of lithium salt remains unchanged, while the mass percentage of organic solvent changes accordingly. The sum of the mass percentages of compound (I), sulfur-oxygen double bond compound, lithium salt and organic solvent is 100%.

[0087] Examples 3-1 and 3-2

[0088] Except for adjusting the relevant preparation parameters according to Table 3, the rest is the same as in Examples 2-3.

[0089] Comparative Examples 1 to 6

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

[0091] The preparation and performance parameters of each embodiment and comparative example are shown in Tables 1 to 3.

[0092] Table 1 Note: In Table 1, "\" indicates that there is no corresponding parameter.

[0093] As can be seen from Examples 1-1 to 1-15 and Comparative Examples 1 to 6, the non-aqueous electrolyte secondary battery of this application, by controlling the thickness T of the positive electrode active material layer in the positive electrode sheet within the range of this application, introducing the compound of formula (I) into the electrolyte and controlling the mass percentage W1% of the compound of formula (I) within the range of this application, and controlling the value of W1 / T within the range of this application, achieves a higher adhesion between the separator and the positive electrode sheet. This results in a lower deformation rate and more cycle cycles for the secondary battery, indicating that the deformation problem during the cycle process of the secondary battery has been improved, and the secondary battery has good cycle performance. In contrast, the secondary batteries of the comparative examples, where at least one of the thickness T of the positive electrode active material layer, the mass percentage W1% of the compound of formula (I), or the value of W1 / T is not within the range of this application, have a lower adhesion between the separator and the positive electrode sheet, and exhibit a greater deformation rate and fewer cycle cycles. This indicates that the deformation problem during the cycle process of the comparative examples has not been improved.

[0094] The mass percentage W1% of the compound of formula (I) typically affects the deformation rate and cycle performance of secondary batteries. As can be seen from Examples 1-1 to 1-5, Comparative Example 1, and Comparative Example 2, secondary batteries using a mass percentage W1% of the compound of formula (I) within the scope of this application exhibit higher adhesion between the separator and the positive electrode, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling is improved, and the secondary battery demonstrates good cycle performance.

[0095] The thickness T of the positive electrode active material layer typically affects the deformation rate and cycle performance of a secondary battery. As can be seen from Examples 1-1, 1-6 to 1-9, Comparative Example 3, and Comparative Example 4, the secondary battery with a positive electrode active material layer thickness T within the scope of this application exhibits higher adhesion between the separator and the positive electrode sheet, resulting in a lower deformation rate and a higher number of cycle cycles. This indicates that the deformation problem during cycling has been improved, and the secondary battery demonstrates good cycle performance.

[0096] The value of W1 / T and the thickness T of the positive electrode active material layer typically affect the deformation rate and cycle performance of the secondary battery. As can be seen from Examples 1-1 to 1-12, Comparative Example 5, and Comparative Example 6, the secondary battery using the W1 / T value within the scope of this application exhibits higher adhesion between the separator and the positive electrode, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling has been improved, and the secondary battery demonstrates good cycle performance.

[0097] The type of compound (I) typically affects the deformation rate and cycle performance of secondary batteries. As can be seen from Examples 1-1, 1-13 to 1-15, secondary batteries using compounds of formula (I) within the scope of this application exhibit higher adhesion between the separator and the positive electrode, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling is improved, and the secondary battery demonstrates good cycle performance.

[0098] Table 2

[0099] Further introduction of sulfur-oxygen double bond compounds into the electrolyte, with the mass percentages W2%, W1 / W2, and W1+W2 of these compounds typically affecting the deformation rate and cycle performance of the secondary battery, demonstrates this. Examples 1-1, 2-1 to 2-13 show that secondary batteries using the selected mass percentages W2%, W1 / W2, and W1+W2 of the sulfur-oxygen double bond compounds within the scope of this application exhibit higher adhesion between the separator and the positive electrode, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling has been improved, and the secondary battery demonstrates excellent cycle performance.

[0100] The particle sizes Dv10, Dv50, and Dv50 / Dv10 of the positive electrode active material typically affect the deformation rate and cycle performance of the secondary battery. As can be seen from Examples 2-1, 2-14 to 2-26, the secondary batteries within the scope of this application, using particle sizes Dv10, Dv50, and Dv50 / Dv10 of the positive electrode active material exhibit high adhesion between the separator and the positive electrode sheet, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling has been improved, and the secondary battery possesses excellent cycle performance.

[0101] The value of (W1+W2)×(Dv50 / Dv10) typically affects the deformation rate and cycle performance of a secondary battery. As can be seen from Examples 2-1 to 2-29, the secondary battery within the scope of this application, using a value of (W1+W2)×(Dv50 / Dv10), exhibits higher adhesion between the separator and the positive electrode, a smaller deformation rate, and a higher number of cycles. This indicates that the deformation problem during cycling is improved, and the secondary battery demonstrates good cycle performance.

[0102] Table 3

[0103] The type of sulfur-oxygen double bond compound typically affects the deformation rate and cycle performance of secondary batteries. As can be seen from Examples 2-3, 3-1, and 3-2, the secondary batteries using sulfur-oxygen double bond compounds within the scope of this application exhibit higher adhesion between the separator and the positive electrode, resulting in a lower deformation rate and a higher number of cycles. This indicates that the deformation problem during cycling is improved, and the secondary batteries demonstrate good cycle performance.

[0104] 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.

[0105] 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.

[0106] 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 sheet and an electrolyte, wherein the positive electrode sheet comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector, the thickness of the positive active material layer being T μm; The electrolyte comprises a compound of formula (I): in, R 11 R 12 R 13 and R 14 Each group is independently selected from hydrogen atoms, halogen atoms, cyano groups, phenyl groups, substituted or unsubstituted C1 to C10 alkyl groups, substituted or unsubstituted C2 to C10 alkenyl groups, substituted or unsubstituted C2 to C10 alkynyl groups, and substituted or unsubstituted C2 to C10 functional groups containing Si or O; when substituted, the substituent is a halogen atom; R 11 R 12 R 13 and R 14 Two adjacent groups in R can connect to form a ring; 11 R 12 R 13 and R 14 At least one of them contains an unsaturated bond; Based on the mass of the electrolyte, the mass percentage of the compound of formula (I) is W1%; T and W1 satisfy: 20≤T≤70, 0.01≤W1≤0.5, 0.0005≤W1 / T≤0.

02.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The secondary battery satisfies at least one of the following characteristics: (1)30≤T≤60； (2)0.05≤W1≤0.15； (3) 0.001≤W1 / T≤0.

01.

3. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The compound of formula (I) includes at least one of tetramethyldivinyldisiloxane, bis(trimethylsilane) maleate, tetraallylsilane, pentamethylpentavinylcyclopentasiloxane, vinyltrimethylsilane, divinyldimethylsilane, 1,3-dimethyl-1,1,3,3-tetraethylenedisiloxane, trivinylmethylsilane, triethylsilylacetylene, tetravinylsilane, tetramethyltetravinylcyclotetrasiloxane, diphenyldifluorosilane, 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, or vinyltriethoxysilane.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein, The electrolyte also includes a sulfur-oxygen double bond compound, and the mass percentage of the sulfur-oxygen double bond compound is W2% based on the mass of the electrolyte. W1 and W2 satisfy: 0.5≤W2≤5, 0.01≤W1 / W2≤0.1, 1≤W1+W2≤5.

2.

5. The non-aqueous electrolyte secondary battery according to claim 4, wherein, The non-aqueous electrolyte secondary battery satisfies at least one of the following characteristics: (i) 1≤W2≤3; (ii) 0.02 ≤ W1 / W2 ≤ 0.05; (iii) 1.2≤W1+W2≤3.

1.

6. The non-aqueous electrolyte secondary battery according to claim 4, wherein, The sulfur-oxygen double bond compound includes at least one of 1,3-propanesulfonate, vinyl sulfate, propenesulfonate lactone, 3-fluoro-1,3-propanesulfonate lactone, 1,2-propanesulfonate lactone, 1,4-butanesulfonate lactone, 1,2-butanesulfonate lactone, 1,3-butanesulfonate lactone, 2,4-butanesulfonate lactone, or 1,3-pentanesulfonate lactone.

7. The non-aqueous electrolyte secondary battery according to claim 4, wherein, The positive electrode active material layer includes a positive electrode active material, and the particle size of the positive electrode active material, Dv10μm and Dv50μm, satisfies the following conditions: 0.5≤Dv10≤5, 1≤Dv50≤10, 1.1≤Dv50 / Dv10≤5.

8. The non-aqueous electrolyte secondary battery according to claim 7, wherein, The non-aqueous electrolyte secondary battery satisfies: 1.1≤(W1+W2)×(Dv50 / Dv10)≤20.

9. The non-aqueous electrolyte secondary battery according to claim 7 or 8, wherein, The non-aqueous electrolyte secondary battery satisfies at least one of the following characteristics: (a) 0.6 ≤ Dv10 ≤ 2; (b) 1.5 ≤ Dv50 ≤ 5; (c) 1.5 ≤ Dv50 / Dv10 ≤ 4; (d)3≤(W1+W2)×(Dv50 / Dv10)≤12.

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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