Electrochemical device and electronic device

Abstract

The present application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive electrode sheet and an electrolyte. The positive electrode sheet comprises a positive electrode current collector, a first material layer and a positive electrode material layer. The first material layer is arranged between the positive electrode current collector and the positive electrode material layer. The first material layer comprises inorganic particles, a first binder, and a first conductive agent. The inorganic particles comprise a metal element. Based on the mass of the first material layer and the positive electrode material layer, the mass percentage of the metal element is M%, wherein 0.3≤M≤4. The electrolyte comprises a first component. The first component comprises at least one of a compound of formula I-1 or a compound of formula II-1. Based on the mass of the electrolyte, the mass percentage of the first component is A%, wherein 40≤A≤85. By means of the described arrangements, the cycling performance of the electrochemical device at high voltage and high temperature can be improved, and the thermal safety performance of the electrochemical device can also be ensured, thereby improving the comprehensive performance of the electrochemical device.

Description

An electrochemical device and an electronic device Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to an electrochemical device and an electronic device. Background Technology

[0002] Electrochemical devices, such as lithium-ion batteries, are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, and environmental friendliness. As the application scope of lithium-ion batteries continues to expand and their application scenarios become more diverse, the market is placing higher demands on their electrochemical performance. For example, to meet the market demand for high-energy-density batteries, a common technical approach is to increase the upper limit of the charging cutoff voltage. Furthermore, with the diversification of application scenarios, lithium-ion batteries must be able to adapt to various climatic conditions, such as maintaining good cycle performance under high-temperature conditions.

[0003] As one of the key materials in lithium-ion batteries, the performance of the electrolyte determines the maximum performance of other materials in the battery, such as the positive electrode, negative electrode, and separator. To improve the cycle performance of lithium-ion batteries under harsh conditions such as high voltage and high temperature, the composition of the electrolyte is usually optimized. Summary of the Invention

[0004] The purpose of this application is to provide an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device under high voltage and high temperature while taking into account the thermal safety performance of the electrochemical device. The specific technical solution is as follows:

[0005] The first aspect of this application provides an electrochemical device comprising a positive electrode and an electrolyte. The positive electrode includes a positive current collector, a first material layer, and a positive electrode material layer. The first material layer is disposed on at least one surface of the positive current collector and between the positive current collector and the positive electrode material layer. The first material layer includes inorganic particles, a first binder, and a first conductive agent. The inorganic particles include a metal element, which is at least one of Al, Mg, Ca, Ti, Ce, Zn, Y, Hf, Zr, Ba, or Sn. Based on the mass of the first material layer and the positive electrode material layer, the mass percentage of the metal element is M%, 0.3 ≤ M ≤ 4. The electrolyte includes a first component, which includes at least one of a compound of formula I-1 or a compound of formula II-1.

[0006] Among them, R 11 and R 12 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 11 and R 12 At least one of them has been replaced; R21 and R 22 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 21 and R 22 At least one of the components is substituted; when substituted, the substituent is a fluorine atom; based on the mass of the electrolyte, the mass percentage of the first component is A%, 40≤A≤85%, preferably, 56≤A≤72%. The electrolyte includes the first component within the scope of this application, and a first material layer is disposed on the positive electrode current collector, which is beneficial to improving the oxidation resistance of the electrolyte and improving the solvation structure of active metal ions (e.g., lithium ions). In addition, it is beneficial to reduce the direct contact between the electrolyte, the positive electrode active material and the positive electrode current collector, and reduce heat generation, thereby improving the cycle performance of the electrochemical device under high voltage and high temperature while also taking into account the thermal safety performance of the electrochemical device.

[0007] In some embodiments of this application, the electrolyte comprises a second component and / or a third component; the second component comprises a compound of formula III:

[0008] Among them, R 41 R 42 R 43 R 44 Each is independently H, F, substituted or unsubstituted C1-C3 alkyl group, and when substituted, the substituent is a fluorine atom, R. 41 R 42 R 43 R 44 At least one of the components contains F; the second component has a mass percentage of B% based on the mass of the electrolyte, 5 ≤ B ≤ 15%; the third component includes a compound of formula I-2:

[0009] Among them, R 13 R 14 Each independently is C1-C 10 Alkyl groups; based on the mass of the electrolyte, the mass percentage of the third component is C%, satisfying: 40 < A + C ≤ 85%. Introducing a second and / or third component into the electrolyte, which already includes the first component, is beneficial for further improving the cycle performance of the electrochemical device under high voltage and high temperature while maintaining good thermal safety performance.

[0010] In some embodiments of this application, the compound of formula I-1 includes at least one of the following compounds:

[0011] Compounds of Formula II-1 include at least one of the following compounds:

[0012] The electrolyte includes at least one of the compounds of formula I-1 or formula II-1 within the above-mentioned range, which is more conducive to improving the oxidation resistance of the electrolyte and to promoting the dissociation of the electrolyte, thereby improving the solvation structure of the electrolyte salt and further improving the cycle performance of the electrochemical device under high voltage and high temperature.

[0013] In some embodiments of this application, the compound of formula III includes at least one of the following compounds:

[0014] The electrolyte includes compounds of formula III within the above-mentioned range, which is more conducive to the formation of a stable solid electrolyte interphase (SEI) film on the negative electrode surface. The first and second components within the scope of this application work synergistically to further improve the cycle performance of the electrochemical device under high voltage and high temperature.

[0015] In some embodiments of this application, the compound of formula I-2 includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, or propyl propionate. Introducing a third component within the aforementioned range into the electrolyte, in addition to including the first component, helps reduce costs while maintaining good cycle performance and thermal safety of the electrochemical device.

[0016] In some embodiments of this application, the electrolyte includes a fourth component, which comprises at least one selected from vinylene carbonate, 1,3-propanesulfonyl lactone, succinate, adiponitrile, or 1,3,6-hexanetrionitrile. Based on the mass of the electrolyte, the mass percentage of the fourth component is D%, 0.1 ≤ D ≤ 6. The inclusion of a fourth component in the electrolyte and the control of its mass percentage within the scope of this application allow the fourth component to form a stable interfacial film at the positive and negative electrode interfaces, further improving the cycle performance of the electrochemical device under high voltage and high temperature, while also ensuring thermal safety.

[0017] In some embodiments of this application, the ratio of the length of the first material layer to the length of the positive electrode current collector is X%, 50≤X≤98, preferably 80≤X≤98. This helps to reduce the direct contact between the electrolyte, the positive electrode active material, and the positive electrode current collector, reduces the occurrence of exothermic reactions, and further improves the thermal safety performance of the electrochemical device.

[0018] In some embodiments of this application, the first binder comprises a copolymer formed by polymerizing acrylate, acrylamide, and acrylonitrile. Based on the mass of the first material layer, the mass percentage of the first binder is N%, 2 ≤ N ≤ 10. Including the first binder within the aforementioned range in the first material layer and controlling the mass percentage of the first binder within the range of this application can ensure good adhesion between the first material layer and the positive electrode material layer and the current collector, thereby further improving the thermal safety and electrochemical performance of the electrochemical device.

[0019] In some embodiments of this application, the inorganic particles include at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, gibbsite, barium sulfate, calcium sulfate, or calcium silicate; the particle size D of the inorganic particles is... V 50 is 0.3 μm to 1.0 μm. The first material layer includes inorganic particles within the above range, and by adjusting the particle size of the inorganic particles within the range of this application, the first material layer can have good ion transport capability and good conductive network electronic conductivity, further improving the cycle performance of the electrochemical device under high voltage and high temperature, while also taking into account thermal safety performance.

[0020] The second aspect of this application provides an electronic device that includes the electrochemical device provided in the first aspect of this application. The electrochemical device provided in the first aspect of this application exhibits good cycle performance under high voltage and high temperature conditions, while also possessing good thermal performance; therefore, the electronic device provided in the second aspect of this application has excellent usability.

[0021] The beneficial effects of this application are:

[0022] This application provides an electrochemical device and an electronic device. The electrochemical device includes a positive electrode and an electrolyte. The positive electrode includes a positive current collector, a first material layer, and a positive electrode material layer, with the first material layer disposed between the positive current collector and the positive electrode material layer. The first material layer includes inorganic particles, a first binder, and a first conductive agent. The inorganic particles include metal elements, and based on the mass of the first material layer and the positive electrode material layer, the mass percentage of the metal elements is M%, 0.3≤M≤4%. The electrolyte includes a first component, which includes at least one compound of formula I-1 or formula II-1. Based on the mass of the electrolyte, the mass percentage of the first component is A%, 40≤A≤85%. This configuration improves the cycle performance of the electrochemical device under high voltage and high temperature conditions while also ensuring its thermal safety, thus enhancing the overall performance of the electrochemical device. Detailed Implementation

[0023] 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.

[0024] It should be noted that, in the specific embodiments of this application, a lithium-ion battery is used as an example of an electrochemical device to explain this application; however, the electrochemical device of this application is not limited to lithium-ion batteries. The specific technical solution is as follows:

[0025] The first aspect of this application provides an electrochemical device comprising a positive electrode and an electrolyte. The positive electrode comprises a positive current collector, a first material layer, and a positive electrode material layer. The first material layer is disposed on at least one surface of the positive current collector and between the positive current collector and the positive electrode material layer. The first material layer comprises inorganic particles, a first binder, and a first conductive agent. The inorganic particles comprise a metal element, which includes at least one of Al, Mg, Ca, Ti, Ce, Zn, Y, Hf, Zr, Ba, or Sn. Based on the mass of the first material layer and the positive electrode material layer, the mass percentage of the metal element is M%, 0.3 ≤ M ≤ 4. The electrolyte comprises a first component, which includes at least one of a compound of formula I-1 or a compound of formula II-1.

[0026] Among them, R 11 and R 12 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 11 and R 12 At least one of them has been replaced; R 21 and R 22 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 21 and R 22 At least one of the components is substituted; when substituted, the substituent is a fluorine atom; based on the mass of the electrolyte, the mass percentage of the first component is A%, 40≤A≤85, preferably, 56≤A≤72. For example, the value of M can be 0.3, 0.5, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, or a range of any two of these values; the value of A can be 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 78, 80, 82, 85, or a range of any two of these values.

[0027] The inventors discovered that the electrolyte includes a first component, which comprises at least one compound of formula I-1 or formula II-1. Because the first component within the scope of this application has a high oxidation potential, it is beneficial for enhancing the electrolyte's oxidation resistance, reducing side reactions under high voltage and high temperature conditions, and reducing gas production. Furthermore, the first component plays a dominant role in the solvation structure of lithium ions, which is beneficial for the dissociation of electrolytes in the electrolyte, promoting electrolyte dissolution and allowing the electrolyte to exist in the electrolyte as active metal ions (e.g., lithium ions), thereby improving the cycle performance of the electrochemical device under high voltage and high temperature conditions. When the value of A is too small, for example, less than 40, the electrolyte's oxidation resistance is weak, and the first component cannot play a dominant role in the solvation structure of lithium ions, failing to effectively improve the cycle performance of the electrochemical device under high voltage and high temperature conditions. When the value of A is too large, for example, greater than 85, the electrolyte viscosity is high, and the electrolyte content is low, failing to provide sufficient lithium ions, increasing polarization, and affecting the electrochemical performance of the electrochemical device. While the electrolyte, including the first component within the scope of this application, is beneficial for improving the cycle performance of the electrochemical device under high voltage and high temperature, the first component within the scope of this application comes into contact with the positive electrode active material and the positive electrode current collector, generating heat and affecting the thermal safety performance of the electrochemical device, especially its heat chamber performance. Therefore, based on the electrolyte including the first component of this application, by setting a first material layer on the surface of the positive electrode current collector, with the first material layer positioned between the positive electrode current collector and the positive electrode material layer, and the first material layer including a metal element, this arrangement helps to reduce direct contact between the electrolyte, the positive electrode active material, and the positive electrode current collector, reducing heat generation and improving heat chamber performance. When the value of M is too small, it is not conducive to isolating the electrolyte and the positive electrode current collector, resulting in a weak improvement in heat chamber performance; when the value of M is too large, it leads to an increase in the impedance of the electrochemical device, deteriorating its cycle performance. This application, by setting a first material layer and using it in conjunction with the first component in the electrolyte, helps to improve the cycle performance of the electrochemical device under high voltage and high temperature while also ensuring the thermal safety performance of the electrochemical device. In this application, high voltage means a voltage greater than or equal to 4.2V, and high temperature means a temperature greater than or equal to 40°C.

[0028] In some embodiments of this application, the electrolyte includes a second component, which includes a compound of formula III:

[0029] Among them, R 41 R 42 R 43 R 44 Each is independently H, F, substituted or unsubstituted C1-C3 alkyl group, and when substituted, the substituent is a fluorine atom, R. 41 R 42 R 43 R44 At least one of the components contains F; based on the mass of the electrolyte, the mass percentage of the second component is B%, 5 ≤ B ≤ 15. For example, the value of B can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a range of any two of these values. Introducing a second component within the scope of this application into the electrolyte, and controlling the mass percentage of the second component within the scope of this application, is beneficial for forming a stable solid electrolyte interphase (SEI) film on the negative electrode surface and reducing gas production. The synergistic effect of these two factors further improves the cycling performance of the electrochemical device under high voltage and high temperature.

[0030] In some embodiments of this application, the electrolyte includes a third component, which includes a compound of formula I-2:

[0031] Among them, R 13 R 14 Each independently is C1-C 10 Alkyl group; based on the mass of the electrolyte, the mass percentage of the third component is C%, satisfying: 40 < A + C ≤ 85. For example, the value of A + C can be 40.5, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 78, 80, 82, 85, or a range of any two of these values. Introducing a third component into the electrolyte, which includes the first component, and controlling the total mass percentage of the first and third components within the range specified in this application, is beneficial for cost reduction, while the electrochemical device still maintains good cycle performance and thermal safety.

[0032] In some embodiments of this application, the electrolyte includes a second component and a third component. The second component includes a compound of formula III, and its mass percentage is B% based on the mass of the electrolyte, with 5 ≤ B ≤ 15%. The third component includes at least one compound of formula I-2 or formula II-2, and its mass percentage is C% based on the mass of the electrolyte, satisfying: 40 < A + C ≤ 85. Introducing a second and third component into the electrolyte, in addition to including a first component, is beneficial for further improving the cycle performance of the electrochemical device under high voltage and high temperature while maintaining good thermal safety performance.

[0033] In some embodiments of this application, the compound of formula I-1 includes at least one of the following compounds:

[0034] Compounds of Formula II-1 include at least one of the following compounds:

[0035] The electrolyte includes at least one of the compounds of formula I-1 or formula II-1 within the above-mentioned range, which is more conducive to improving the oxidation resistance of the electrolyte and to the dissociation of the electrolyte, providing a good solvation structure for the electrolyte salt, thereby further improving the cycle performance of the electrochemical device under high voltage and high temperature.

[0036] In some embodiments of this application, the compound of formula III includes at least one of the following compounds:

[0037] The electrolyte includes compounds of formula III within the above-mentioned range, which is more conducive to the formation of a stable solid electrolyte interphase (SEI) film on the negative electrode surface. The first and second components within the scope of this application work synergistically to further improve the cycle performance of the electrochemical device under high voltage and high temperature.

[0038] In some embodiments of this application, the compound of formula I-2 includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, or propyl propionate. Introducing a third component within the aforementioned range into the electrolyte, in addition to including the first component, helps reduce costs while maintaining good cycle performance and thermal safety of the electrochemical device.

[0039] In some embodiments of this application, the electrolyte includes a fourth component, which comprises at least one selected from vinylene carbonate, 1,3-propanesulfonyl lactone, succinate, adiponitrile, or 1,3,6-hexanetrionitrile. The mass percentage of the fourth component is D%, 0.1 ≤ D ≤ 6, based on the mass of the electrolyte. For example, the value of D can be 0.1, 0.5, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.3, 4.8, 5, 5.2, 5.5, 5.8, 6, or a range of any two of these values. The electrolyte includes a fourth component, and the mass percentage of the fourth component is controlled within the scope of this application. The fourth component preferentially forms a stable interfacial film at the positive and negative electrode interfaces, prior to the first, second, and third components, reducing the reactions of the first, second, and third components at the positive and negative electrode interfaces. This further improves the cycle performance of the electrochemical device under high voltage and high temperature, while also ensuring thermal safety. Preferably, the fourth component is selected from at least one of butadionitrile, adiponitrile, or 1,3,6-hexanetrionitrile. When the fourth component is selected from the above-mentioned nitrile compounds, it is beneficial to further improve the cycle performance of the electrochemical device under high voltage and high temperature, and also to further improve thermal safety.

[0040] In some embodiments of this application, the electrolyte may also include other non-aqueous solvents. This application does not impose any particular limitation on these other non-aqueous solvents, as long as they achieve the purpose of this application. For example, other non-aqueous solvents may include, but are not limited to, at least one of dimethyl carbonate, diethyl carbonate, or methyl ethyl carbonate. This application does not impose any particular limitation on the content of other non-aqueous solvents in the electrolyte, as long as they achieve the purpose of this application. For example, based on the mass of the electrolyte, the mass percentage of other non-aqueous solvents may be from 0% to 52%.

[0041] In this application, the electrolyte includes an electrolyte, and there are no particular limitations on the electrolyte, as long as it achieves the purpose of this application. For example, the electrolyte may include, but is not limited to, at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, Li2SiF6, lithium bis(oxalato)borate (LiBOB), or lithium difluoroborate. There are no particular limitations on the content of the electrolyte in the electrolyte, as long as it achieves the purpose of this application. For example, based on the mass of the electrolyte, the mass percentage of the electrolyte may be 8% to 15%.

[0042] In some embodiments of this application, the ratio of the length of the first material layer to the length of the positive electrode current collector is X%, 50≤X≤98, preferably 80≤X≤98. For example, the value of X can be 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, 98, or a range of any two of these values. By setting the first material layer on the surface of the positive electrode current collector and adjusting the ratio of the length of the first material layer to the length of the positive electrode current collector within the range of this application, it is beneficial to reduce the direct contact between the electrolyte, the positive electrode active material, and the positive electrode current collector, reduce the occurrence of exothermic reactions, and further improve the thermal safety performance of the electrochemical device.

[0043] This application does not impose any particular limitation on the coating area of ​​the first material layer on the surface of the positive electrode current collector, as long as the purpose of this application is achieved. In some embodiments of this application, the first material layer is disposed at one end of the positive electrode current collector, while the other end does not have a first material layer. In other embodiments of this application, the first material layer is disposed in the middle region of the positive electrode current collector, while both ends of the positive electrode current collector do not have a first material layer. Preferably, the first material layer is disposed at one end of the positive electrode current collector, while the other end does not have a first material layer, and the end of the positive electrode sheet with the first material layer is close to the center of the wound electrode assembly. This application does not impose any particular limitation on the thickness of the first material layer, as long as the purpose of this application is achieved. For example, the thickness of the first material layer on one side is 1 μm to 10 μm.

[0044] In some embodiments of this application, the first binder comprises a copolymer formed by polymerizing acrylate, acrylamide, and acrylonitrile. Based on the mass of the first material layer, the mass percentage of the first binder is N%, 2 ≤ N ≤ 10. For example, the value of N can be 2, 3, 4, 5, 6, 7, 8, 9, 10, or a range consisting of any two of these values. The acrylate may include, but is not limited to, at least one of lithium acrylate, sodium acrylate, or potassium acrylate. Including the first binder within the aforementioned range in the first material layer and controlling the mass percentage of the first binder within the scope of this application can ensure good adhesion between the first material layer and the positive electrode material layer and the positive electrode current collector, reducing the shedding of the first material layer and reducing loosening or detachment of the positive electrode material layer under abnormal conditions, thereby further improving the thermal safety and electrochemical performance of the electrochemical device.

[0045] In this application, the first binder comprises a copolymer formed by polymerizing acrylate, acrylamide, and acrylonitrile. This application does not impose any particular limitation on the proportions of acrylate, acrylamide, and acrylonitrile in the copolymer, as long as the purpose of this application is achieved. In some embodiments of this application, based on the mass of the copolymer, the mass percentage of acrylonitrile is 40% to 60%, the mass percentage of acrylate is 10% to 50%, and the mass percentage of acrylamide is 10% to 50%. This application does not impose any particular limitation on the weight-average molecular weight of the first binder, as long as the purpose of this application is achieved; for example, the weight-average molecular weight of the first binder is 300,000 to 900,000.

[0046] This application does not impose any particular limitation on the preparation method of the first binder. Preparation methods known to those skilled in the art can be used. For example, the preparation method of the first binder is as follows: Distilled water is added to a reaction vessel, the stirrer is started, nitrogen gas is introduced to remove oxygen, then acrylate, acrylamide, and acrylonitrile are added. The mixture is heated to 60°C to 70°C under an inert atmosphere and kept at a constant temperature. Then, an initiator is added to initiate the reaction. After reacting for 18 to 22 hours, an alkaline solution is added to the reaction vessel to adjust the pH of the solution to 6.5 to 9. The reactants are then filtered, washed, dried, pulverized, and sieved to obtain the first binder. This application does not impose any particular limitation on the type of initiator, as long as it achieves the purpose of this application. For example, it can be a 20% ammonium sulfate solution. This application does not impose any particular limitation on the amount of distilled water and initiator, as long as it enables the polymerization reaction of acrylate, acrylamide, and acrylonitrile.

[0047] In some embodiments of this application, the inorganic particles include at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, gibbsite, barium sulfate, calcium sulfate, or calcium silicate; the particle size D of the inorganic particles is... V 50 is 0.3 μm to 1.0 μm. For example, the particle size of inorganic particles can be 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, or any two of these values. The first material layer includes inorganic particles within the above range, and by controlling the particle size of the inorganic particles within the range of this application, the first material layer can possess good ion transport capability and good conductive network electronic conductivity, further improving the cycle performance of the electrochemical device under high voltage and high temperature, while also considering thermal safety performance.

[0048] In this application, the first material layer includes a first conductive agent. This application does not particularly limit the type of the first conductive agent, as long as it achieves the purpose of this application. For example, the first conductive agent may include, but is not limited to, at least one of graphene, carbon nanotubes, conductive carbon black, or graphite fiber. This application does not particularly limit the mass percentage content of the first conductive agent in the first material layer, as long as it achieves the purpose of this application. For example, based on the mass of the first material layer, the mass percentage content of the first conductive agent is from 0.1% to 20%.

[0049] In some embodiments of this application, the first material layer may further include a leveling agent. This application does not particularly limit the type of leveling agent, as long as it achieves the purpose of this application. Leveling agents include, but are not limited to, at least one of polyethoxypropoxypropylene, polysiloxane, polymethyl methacrylate, polyethylene glycol, sodium polycarboxylate, or polyacrylamide. This application does not particularly limit the mass percentage content of the leveling agent in the first material layer, as long as it achieves the purpose of this application. For example, based on the mass of the first material layer, the mass percentage content of the leveling agent is from 0.01% to 10%.

[0050] This application does not impose any particular restrictions on the positive electrode current collector, as long as it can achieve the purpose of this application. For example, it may include aluminum foil, aluminum alloy foil, or composite current collector (such as aluminum-carbon composite current collector).

[0051] In this application, the positive electrode material layer includes a positive electrode active material. This application does not particularly limit the type of positive electrode active material, as long as it can achieve the purpose of this application. The positive electrode active material includes compounds that reversibly insert and extract lithium ions. In some embodiments, the positive electrode material layer includes a positive electrode active material with an operating potential of 4.5V or higher relative to metallic lithium. That is, the positive electrode active material of this application can operate under high voltage. In some embodiments, the positive electrode active material may include at least one of lithium nickel cobalt manganese oxide (NCM), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, or lithium manganese iron phosphate. Lithium nickel cobalt manganese oxide may include, but is not limited to, LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333) or LiNi 0.9 Co 0.05 Mn 0.05 At least one of O2 (NCM955).

[0052] The positive electrode material layer may also include a conductive agent and a binder. This application does not impose any particular limitation on the types of conductive agents and binders, as long as they achieve the purpose of this application. For example, the conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, graphene, metallic materials, or conductive polymers. The aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The aforementioned carbon fibers may include, but are not limited to, vapor-grown carbon fibers (VGCF) and / or carbon nanofibers. The aforementioned metallic materials may include, but are not limited to, metal powders and / or metal fibers; specifically, the metal may include, but is not limited to, at least one of copper, nickel, aluminum, or silver. The aforementioned conductive polymer may include, but is not limited to, at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene, or polypyrrole. The binder may include, but is not limited to, at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyimide, polyamide-imide, styrene-butadiene rubber, or polyvinylidene fluoride. This application does not impose any particular restrictions on the mass ratio of positive electrode active material, conductive agent, and binder in the positive electrode material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of this application can be achieved.

[0053] This application does not impose any particular limitations on the thickness of the positive electrode current collector and the positive electrode material layer, as long as the purpose of this application can be achieved. For example, the thickness of the positive electrode current collector can be 5 μm to 20 μm, and the thickness of the single-sided positive electrode material layer can be 30 μm to 120 μm.

[0054] In this application, the positive electrode material layer can be disposed on one surface or on two surfaces along the thickness direction of the positive electrode current collector. It should be noted that "surface" here can refer to the entire surface of the positive electrode current collector or only a portion thereof; this application has no particular limitation, as long as the purpose of this application is achieved. The first material layer is coated between the positive electrode material layer and the positive electrode current collector. It can be understood that in areas of the positive electrode current collector not coated with the first material layer, the positive electrode material layer is in direct contact with the positive electrode current collector.

[0055] In this application, there are no particular limitations on the preparation method of the positive electrode sheet, as long as the purpose of this application can be achieved. For example, it can be prepared by the following method: Inorganic particles, a first binder, and a first conductive agent are mixed, deionized water is added, and the mixture is stirred evenly to obtain a first material layer slurry with a solid content of 10% to 50%. The first material layer slurry is coated on the surface area of ​​the positive electrode current collector, and after drying, a positive electrode current collector with a single-sided coating of the first material layer is obtained. Then, the above coating steps are repeated on the other surface of the positive electrode current collector, and after drying, a positive electrode current collector with a double-sided coating of the first material layer is obtained. Then, the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder are mixed, and N-methylpyrrolidone (NMP) is added and stirred evenly to obtain a positive electrode slurry with a solid content of 65wt% to 85wt%. The positive electrode slurry is uniformly coated on one surface of the positive electrode current collector coated with the first material layer, and after drying, a positive electrode sheet with a single-sided coating of the positive electrode material layer is obtained. Then, repeat the above coating steps on the other surface of the positive current collector coated with the first material layer. After drying, a positive electrode sheet with a double-sided coated positive material layer is obtained. After coating, the positive electrode sheet is obtained by cold pressing and cutting.

[0056] In this application, the electrochemical device further includes a negative electrode sheet, which comprises a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector. The phrase "the negative electrode material layer is disposed on at least one surface of the negative electrode current collector" means that the negative electrode material layer can be disposed on one surface of the negative electrode current collector along its thickness direction, or on two surfaces of the negative electrode current collector along its thickness direction. It should be noted that the term "surface" here can refer to the entire surface area of ​​the negative electrode current collector, or only a portion thereof; this application does not impose any particular limitation, as long as the purpose of this application is achieved.

[0057] This application does not impose any particular restrictions on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, it may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collector. For example, the composite current collector may be lithium copper composite current collector, carbon copper composite current collector, nickel copper composite current collector, titanium copper composite current collector, etc.

[0058] The negative electrode material layer includes a negative electrode active material. This application does not impose any particular limitation on the negative electrode active material, as long as it can achieve the purpose of this application. For example, the negative electrode active material may include, but is not limited to, natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-structured lithiated TiO2-Li4Ti5O. 12 Or at least one of Li-Al alloys.

[0059] The negative electrode active material layer of this application may further include a conductive agent and a binder. This application does not impose any particular limitations on the conductive agent and binder, as long as they achieve the purpose of this application. For example, the binder and conductive agent may include, but are not limited to, at least one of the substances selected for the positive electrode material layer described above. This application does not impose any particular limitations on the mass ratio of the negative electrode active material, conductive agent, and binder in the negative electrode material layer; those skilled in the art can select them according to actual needs, as long as the purpose of this application is achieved.

[0060] In this application, there are no particular limitations on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of this application can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 12 μm, and the thickness of the single-sided negative electrode active material layer is 30 μm to 130 μm.

[0061] In this application, there are no particular limitations on the preparation method of the negative electrode sheet, as long as it achieves the purpose of this application. For example, it can be prepared by the following method: mixing negative electrode active material, negative electrode binder, and negative electrode dispersant, adding deionized water and stirring evenly to obtain a negative electrode slurry with a solid content of 55wt% to 70wt%. The negative electrode slurry is uniformly coated on one surface of the negative electrode current collector, and after drying, a negative electrode sheet with a single-sided negative electrode material layer is obtained. Then, the above coating steps are repeated on the other surface of the negative electrode current collector, and after drying, a negative electrode sheet with a double-sided negative electrode material layer is obtained. After coating, the negative electrode sheet is obtained by cold pressing and cutting.

[0062] The electrochemical device of this application also includes a diaphragm to separate the positive and negative electrode plates, prevent internal short circuits, allow electrolyte ions to pass freely, and not affect the electrochemical charging and discharging process. In this application, the electrochemical device also includes a diaphragm. 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.

[0063] In some embodiments of this application, the diaphragm may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, membrane, or composite membrane with a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate, or polyimide. Optionally, a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane may be used.

[0064] Optionally, a surface treatment layer is provided on at least one surface of the substrate layer. The surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic substances.

[0065] In some embodiments of this application, the inorganic layer comprises inorganic particles and a binder. This application does not particularly limit the inorganic particles; for example, the inorganic particles may include at least one selected from alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. This application does not particularly limit the binder; for example, the binder may be at least one of the binders described above. In some embodiments of this application, the polymer layer comprises a polymer, the polymer material of which includes at least one selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, or polyvinylidene fluoride or poly(vinylidene fluoride-hexafluoropropylene).

[0066] In this application, there is no particular limitation on the thickness of the diaphragm, as long as it can achieve the purpose of this application. For example, the thickness of the diaphragm can be from 3 μm to 30 μm.

[0067] The electrochemical device of this application also includes a housing for accommodating the positive electrode, the separator, the negative electrode, and the electrolyte, as well as other components known in the field of electrochemical devices. This application does not limit the scope of these other components. This application does not impose any particular limitation on the housing; it can be a housing known in the art, as long as it achieves the purpose of this application. For example, the housing can be a rigid housing or a flexible housing. The material of the rigid housing can be metal; this application does not limit the type of metal and can use known metal rigid housings, as long as they achieve the purpose of this application. The flexible housing can be a metal-plastic film, such as aluminum-plastic film, steel-plastic film, etc.

[0068] The electrochemical device described in this application is not particularly limited and may include any device in which an electrochemical reaction occurs. In some embodiments of this application, the electrochemical device may include, but is not limited to, lithium-ion batteries, sodium-ion batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0069] The preparation process of the electrochemical device described in this application is well known to those skilled in the art, and this application does not impose any particular limitations. For example, it may include, but is not limited to, the following steps: stacking the positive electrode, separator, and negative electrode in sequence, and performing operations such as winding and folding as needed to obtain a wound electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain the electrochemical device. Alternatively, stacking the positive electrode, separator, and negative electrode in sequence, and then fixing the four corners of the entire stacked structure with tape to obtain a stacked electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain the electrochemical device. In addition, overcurrent protection elements, conductive plates, etc., may be placed in the housing as needed to prevent pressure rise and overcharging / discharging inside the electrochemical device.

[0070] The second aspect of this application provides an electronic device that includes the electrochemical device provided in the first aspect of this application. The electrochemical device provided in the first aspect of this application exhibits good cycle performance under high voltage and high temperature conditions, while also possessing good thermal performance; therefore, the electronic device provided in the second aspect of this application has excellent usability.

[0071] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, laptops, 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, large household batteries, and lithium-ion capacitors, etc.

[0072] Example

[0073] 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. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0074] Test methods and equipment:

[0075] Test for the mass percentage (M%) of metallic elements

[0076] The lithium-ion battery was discharged to 3V at 0.2C, and the positive electrode sheet was obtained by disassembly. The positive electrode sheet was cleaned with DMC (dimethyl carbonate) and dried. A piece of the positive electrode sheet with both a first material layer and a positive electrode material layer coated on the positive current collector was cut. The positive electrode material layer and the first material layer were scraped off with a scraper to obtain a solid powder. 0.4g of the powder was dissolved in 12mL of a mixed solvent, which was prepared by mixing aqua regia and HF in a volume ratio of 5:1. The solution was then diluted to 100mL, and the content of metal elements such as Al, Mg, Ca, and Ti in the solution was tested using an inductively coupled plasma optical emission spectrometer (ICP). The mass percentage (M%) of the metal element based on the mass of the first material layer and the positive electrode material layer was calculated. The aqua regia was prepared by mixing concentrated nitric acid and concentrated hydrochloric acid in a volume ratio of 1:1.

[0077] Testing of the ratio X of the length of the first material layer to the length of the positive electrode current collector.

[0078] In an environment of (25±3)℃, the lithium-ion battery was disassembled to obtain the positive electrode sheet. The residual electrolyte on the surface of the positive electrode sheet was wiped off with lint-free paper. The positive electrode material layer was wiped along the length of the electrode strip with anhydrous ethanol to expose the first material layer. The length of the first material layer and the length of the current collector were measured, and their ratio X was calculated.

[0079] Cyclic performance test

[0080] At 45℃ and ambient pressure (0.1MPa), the lithium-ion battery was charged at a constant current of 0.5C to a voltage of 4.55V, then charged at a constant voltage of 4.55V to a current of 0.02C, and then allowed to stand for 5 minutes. Next, it was discharged at a constant current of 1C to a voltage of 3.0V, and allowed to stand for 5 minutes. This constitutes one charge-discharge cycle, and the discharge capacity of the first cycle was recorded. The lithium-ion battery was subjected to N charge-discharge cycle tests using the above method, and the discharge capacity of the Nth cycle was measured. The capacity retention rate (%) after N cycles of the lithium-ion battery = discharge capacity of the Nth cycle / discharge capacity of the first cycle × 100%. The number of cycles when the capacity retention rate of the lithium-ion battery reached 80% was recorded. A higher number of cycles indicates better cycle performance of the lithium-ion battery under high voltage and high temperature.

[0081] Hot box test

[0082] At 25℃, the lithium-ion battery is charged at a constant current of 0.5C to a voltage of 4.55V, and then charged at a constant voltage of 4.55V to a current of 0.02C. This fully charged lithium-ion battery is then placed in a test chamber according to the test methods specified in GB 31241-2022 "Safety Technical Specifications for Lithium-ion Batteries and Battery Packs for Portable Electronic Products". The test chamber is heated at a rate of 5℃ / min ± 2℃ / min. Once the temperature inside the chamber reaches the predetermined temperature (e.g., 130℃ ± 2℃), it is held at this temperature for 30 minutes, observing whether the battery ignites or explodes. If it does not ignite or explode, it is considered a pass; otherwise, it is a fail.

[0083] Example 1-1

[0084] <Preparation of the First Adhesive>

[0085] Distilled water was added to the reactor and stirring was started. After purging with nitrogen for 2 hours to remove oxygen, the following monomers—acrylonitrile, lithium acrylate, and acrylamide—were added to the reactor at a mass ratio of 45:45:10. The reactor was heated to 65°C under an inert atmosphere and maintained at a constant temperature. Then, a 20% ammonium persulfate solution was added as an initiator to start the reaction. After 22 hours of reaction, the precipitate was removed, and the pH was neutralized to 6.5 with alkali solution. The mass ratio of distilled water, monomers, and initiator was 89.5:10:0.5. After the reaction, the reaction product was filtered, washed, dried, pulverized, and sieved to obtain the first binder.

[0086] <Preparation of the positive electrode>

[0087] Preparation of the first material layer: Inorganic alumina particles (particle size D) are prepared... VThe first binder and the first conductive agent (Super P) prepared above were mixed in a mass ratio of 90:5:5, and deionized water was added to prepare a first material layer slurry with a solid content of 40%. The first material layer slurry was uniformly coated onto one surface of a 3μm thick positive electrode current collector aluminum foil using a gravure coating method. The ratio of the length of the first material layer to the length of the positive electrode current collector aluminum foil was 98%, meaning that 2% of the aluminum foil area remained at the other end. The mixture was dried at 80°C to obtain a single-sided coating weight of 5mg / 1540.25mm. 2 Then, repeat the above steps on the other surface of the aluminum foil to obtain an aluminum foil with the first material layer coated on both sides. It should be noted that the empty aluminum foil areas on both surfaces of the aluminum foil are at the same end.

[0088] Preparation of the positive electrode material layer: Lithium cobalt oxide (LiCoO2), the positive electrode conductive agent Super P, and the positive electrode binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97.3:1.1:1.6. N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75%, and the mixture was stirred evenly. The positive electrode material layer slurry was applied along one end of the aluminum foil coated with the first material layer, with the length of the positive electrode material layer to the length of the aluminum foil being 98%, meaning the positive electrode material layer was coated on the surface of the first material layer. The coating was then dried at 110°C to obtain a positive electrode sheet with a single-sided positive electrode material layer. The above steps were then repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet with a double-sided positive electrode active material coating. After cold pressing and slitting, positive electrode sheets with a specification of 1400mm×70mm are obtained for use (the coating size of the first material layer on both surfaces of the positive electrode sheet is 1372mm×68mm, and the coating size of the positive electrode material layer on both surfaces of the positive electrode sheet is 1372mm×68mm). The thickness of the first material layer on one side is 3μm, and the thickness of the positive electrode material layer on one side is 39μm.

[0089] <Preparation of Negative Electrode Sheets>

[0090] Artificial graphite, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) were mixed at a mass ratio of 97:1.5:1.5. Deionized water was then added as a solvent to prepare a slurry with a solid content of 45 wt%, which was stirred evenly. The slurry was uniformly coated onto one surface of a 5 μm thick copper foil, dried at 110°C, and cold-pressed to obtain a single-sided coated negative electrode sheet with a negative electrode material layer thickness of 50 μm. The above steps were repeated on the other surface of the copper foil to obtain a double-sided coated negative electrode sheet. The negative electrode sheet was cut into 1400 mm × 70 mm dimensions and tabs were welded on for later use.

[0091] <Preparation of Electrolyte>

[0092] In an argon-filled glove box (moisture <10ppm, oxygen <1ppm), the first component, formula I-3A, and diethyl carbonate were mixed uniformly at a mass ratio of 40:45. Then, lithium hexafluorophosphate (LiPF6), succinate (SN), 1,3,6-hexanetrionitrile (HTCN), and lithium difluorophosphate (LiPO2F2) were added to the solvent and mixed uniformly to obtain the electrolyte. Based on the mass of the electrolyte, the mass percentage of LiPF6 was 12.5%, the mass percentage of succinate (SN) was 1%, the mass percentage of 1,3,6-hexanetrionitrile (HTCN) was 1%, the mass percentage of LiPO2F2 was 0.5%, the mass percentage of formula I-3A was 40%, and the mass percentage of diethyl carbonate was 45%.

[0093] <Septum>

[0094] A 5μm thick porous polyethylene (PE) membrane (manufacturer: Celgard Membrane Inc., USA) was used as the separator.

[0095] <Preparation of Lithium-ion Batteries>

[0096] The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets to provide isolation. Simultaneously, one end of the positive electrode sheet coated with the first material layer is ensured to be close to the center of the pre-wound electrode assembly. The assembly is then wound into an electrode assembly, placed in an aluminum-plastic film packaging bag, and dried in an 85°C vacuum oven for 12 hours to remove moisture. Electrolyte is then injected, and the battery undergoes vacuum sealing, settling, formation, degassing, edge trimming, and shaping processes to obtain a lithium-ion secondary battery. The upper limit of the formation voltage is 4.5V, the formation temperature is 85°C, and the settling time is 2 hours.

[0097] Examples 1-2 to Examples 1-5

[0098] Except for the adjustment of the mass percentage of the first component according to Table 1 in the <Preparation of Electrolyte>, which changes the mass percentage of diethyl carbonate accordingly, the rest is the same as in Example 1-1.

[0099] Examples 1-6 to Examples 1-10

[0100] Except for adjusting the type of the first component according to Table 1 in the <Preparation of Electrolyte>, the rest is the same as in Examples 1-4.

[0101] Examples 1-11 to Examples 1-13

[0102] Except for the adjustment of the type of inorganic particles in the first material layer according to Table 1 in the <Preparation of Positive Electrode Sheet>, and the change of the mass percentage M of the metal element accordingly, the rest is the same as in Examples 1-4.

[0103] Examples 1-14 to Examples 1-15

[0104] Except for adjusting the thickness of the first material layer according to Table 1 in the <Preparation of Positive Electrode Sheet>, and changing the mass percentage M of the metal element accordingly, the rest is the same as in Examples 1-4.

[0105] Examples 1-16 to Examples 1-18

[0106] Except for adjusting the ratio X of the length of the first material layer to the length of the positive current collector according to Table 1 in the <Preparation of the Positive Electrode> section, the rest is the same as in Examples 1-4. Specifically, the thickness of the positive electrode material layer on one side of the positive current collector coated with the first material layer is 39 μm, and the thickness of the positive electrode material layer on one side of the positive current collector without the first material layer coating is 42 μm.

[0107] Examples 2-1 to 2-5

[0108] Except for the section on "Preparation of Electrolyte," where a second component is introduced into the electrolyte and its type and mass percentage are adjusted according to Table 2, resulting in a change in the mass percentage of diethyl carbonate, the rest of the process is the same as in Examples 1-4. Specifically, the electrolytes in Examples 2-3 do not include diethyl carbonate; the content of LiPF6 is adjusted to 10.5%, adiponitrile to 1%, 1,3,6-hexanetrionitrile to 1%, and LiPO2F2 to 0.5%.

[0109] Examples 2-6 to 2-10

[0110] Except for the introduction of a third component into the electrolyte in the <Preparation of Electrolyte> section, where the type and mass percentage of the third component and the mass percentage of the first component are adjusted according to Table 2, and the mass percentage of diethyl carbonate is changed accordingly, the rest is the same as in Examples 1-4.

[0111] Examples 2-11 to 2-15

[0112] Except for the adjustment of the type and mass percentage of the fourth component in <Preparation of Electrolyte> according to Table 2, and the change in the mass percentage of diethyl carbonate, the rest are the same as in Examples 1-4.

[0113] Examples 2-16 to 2-21

[0114] Except for the adjustment of relevant parameters according to Table 2 in the <Preparation of Electrolyte>, which changes the mass percentage of diethyl carbonate accordingly, the rest is the same as in Examples 1-4.

[0115] Examples 3-1 to 3-2

[0116] Except for the adjustment of the mass percentage of the first binder according to Table 3 in the <Preparation of the Positive Electrode> section, which alters the mass percentage of inorganic particles accordingly, the rest is the same as in Examples 1-4. Specifically, in Example 3-1, the mass percentage of inorganic particles in the first material layer is 93%, and the mass percentage M of the metal element is 3%; in Example 3-2, the mass percentage of inorganic particles in the first material layer is 85%, and the mass percentage M of the metal element is 2.7%.

[0117] Examples 3-3 to 3-4

[0118] Except for adjusting the monomer mass ratio according to Table 3 in the <Preparation of the First Binder>, the rest is the same as in Examples 1-4.

[0119] Examples 3-5 to Examples 3-6

[0120] Except for the section on "Preparation of Positive Electrode Sheet", which uses inorganic particles with different Dv50 according to Table 3, the rest is the same as in Examples 1-4.

[0121] Comparative Example 1

[0122] Except for the fact that in the "Preparation of Positive Electrode Sheet", the first material layer was not coated on the positive current collector and the thickness of the single-sided positive electrode material layer was 42 μm, the rest was the same as in Examples 1-4.

[0123] Comparative Example 2

[0124] Except for the adjustment of the mass percentage of the first component according to Table 1 in the <Preparation of Electrolyte>, which changes the mass percentage of diethyl carbonate accordingly, the rest is the same as in Examples 1-4.

[0125] Comparative Example 3

[0126] Except for the following in <Preparation of Electrolyte>, where the mass percentage of the first component is adjusted according to Table 1, diethyl carbonate is not included in the electrolyte, and the mass percentage of LiPF6 is 10%, the rest are the same as in Examples 1-4.

[0127] Comparative Examples 4 to 5

[0128] Except for adjusting the thickness of the first material layer according to Table 1 in the <Preparation of Positive Electrode Sheet>, and changing the mass percentage M of the metal element accordingly, the rest is the same as in Examples 1-4.

[0129] The relevant parameters and performance tests of each embodiment and comparative example are shown in Tables 1 to 3.

[0130] Table 1

[0131] Note: In Table 1, " / " indicates that the corresponding substance or parameter does not exist.

[0132] As can be seen from Examples 1-1 to 1-18 and Comparative Examples 1 to 5, the positive electrode sheet includes a first material layer and the mass percentage M of the metal element is controlled within the scope of this application. The electrolyte includes a first component and the value of A is controlled within the scope of this application. This allows the lithium-ion battery to have a higher cycle count and a higher hot box test pass temperature, indicating that the lithium-ion battery has good cycle performance and good thermal safety performance under high voltage and high temperature conditions. Comparative Example 1 does not have a first material layer. Although its lithium-ion battery has a high cycle count, its hot box test pass temperature is low, indicating that the thermal safety performance of the lithium-ion battery is poor. The mass percentage of the first component of the electrolyte in Comparative Examples 2 and 3 is not within the scope of this application, and the cycle performance and thermal safety performance of their lithium-ion batteries cannot be simultaneously achieved. The mass percentage of the metal element in Comparative Examples 4 and 5 is not within the scope of this application, and the cycle performance and thermal safety performance of their lithium-ion batteries cannot be simultaneously achieved.

[0133] The type of the first component typically affects the cycle performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4, 1-6 to 1-10, when the first component within the scope of this application is selected, the lithium-ion battery exhibits a higher number of cycle cycles and a higher hot box test pass temperature, indicating that the lithium-ion battery has good cycle performance under high voltage and high temperature conditions, as well as good thermal safety performance.

[0134] The type of inorganic particles typically affects the cycle performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4 and Examples 1-11 to 1-13, lithium-ion batteries using inorganic particles within the scope of this application exhibit higher cycle counts and higher hot box test pass temperatures, indicating that lithium-ion batteries not only have good cycle performance under high voltage and high temperature conditions but also good thermal safety performance.

[0135] The ratio X of the length of the first material layer to the length of the positive electrode current collector typically affects the cycle performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4, 1-16 to 1-18, by adjusting the value of X within the range of this application, lithium-ion batteries exhibit higher cycle counts and higher hot box test pass temperatures, indicating that lithium-ion batteries possess good cycle performance under high voltage and high temperature conditions, while also exhibiting good thermal safety performance.

[0136] Table 2

[0137] Note: In Table 2, " / " indicates that the corresponding substance or parameter does not exist.

[0138] The type and mass percentage of the second component typically affect the cycle performance and thermal safety performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4 and Examples 2-1 to 2-5, when the electrolyte includes the second component within the scope of this application and the mass percentage of the second component is controlled within the scope of this application, the lithium-ion battery exhibits a higher number of cycle cycles and a higher hot box test pass temperature. This indicates that the cycle performance of the lithium-ion battery under high voltage and high temperature conditions is further improved, while simultaneously possessing good thermal safety performance.

[0139] The type and mass percentage of the third component typically affect the cycle performance and thermal safety performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4 and Examples 2-6 to 2-10, when the electrolyte includes the third component within the scope of this application and the mass percentage of the third component is controlled within the scope of this application, the lithium-ion battery exhibits a higher number of cycle cycles and a higher hot box test pass temperature. This indicates that the lithium-ion battery possesses good cycle performance under high voltage and high temperature conditions, while also exhibiting good thermal safety performance.

[0140] The type and mass percentage of the fourth component typically affect the cycle performance and thermal safety performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4 and Examples 2-11 to 2-15, when the electrolyte includes the fourth component within the scope of this application and its mass percentage is controlled within this scope, the lithium-ion battery exhibits a higher number of cycle cycles and a higher hot box test pass temperature. This indicates that the cycle performance of the lithium-ion battery under high voltage and high temperature conditions is further improved, while simultaneously possessing good thermal safety performance.

[0141] As can be seen from Examples 1-4, 2-2, 2-8, 2-12, 2-16 to 2-21, the positive electrode includes a first material layer and the mass percentage M of the metal element is controlled within the scope of this application. Furthermore, the electrolyte, based on the first component within the scope of this application, further introduces at least one of the second, third, and fourth components. The first component and at least one of the second, third, and fourth components have good superposition properties. The lithium-ion battery has a higher cycle count and a higher hot box test pass temperature, indicating that the cycle performance of the lithium-ion battery under high voltage and high temperature conditions is further improved, and it also has good thermal safety performance.

[0142] Table 3

[0143] Note: In Table 3, " / " indicates that the corresponding substance or parameter does not exist.

[0144] The type and mass percentage of the first binder typically affect the cycle performance and thermal safety performance of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4 and Examples 3-1 to 3-4, by selecting the first binder within the scope of this application and adjusting its mass percentage within the range of this application, the lithium-ion battery exhibits a higher number of cycle cycles and a higher hot box test pass temperature. This indicates that the lithium-ion battery possesses good cycle performance under high voltage and high temperature conditions, while also exhibiting good thermal safety performance.

[0145] The particle size Dv50 of inorganic particles typically affects the cycle performance and thermal safety of lithium-ion batteries under high voltage and high temperature conditions. As can be seen from Examples 1-4, 3-5, and 3-6, lithium-ion batteries using the inorganic particles within the scope of this application exhibit higher cycle counts and higher thermal chamber test pass temperatures, indicating that the lithium-ion batteries possess both good cycle performance and good thermal safety under high voltage and high temperature conditions.

[0146] 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. An electrochemical device comprising a positive electrode and an electrolyte, the positive electrode comprising a positive current collector, a first material layer, and a positive electrode material layer, wherein the first material layer is disposed on at least one surface of the positive current collector, and the first material layer is disposed between the positive current collector and the positive electrode material layer; the first material layer comprises inorganic particles, a first binder, and a first conductive agent, the inorganic particles comprising a metal element, the metal element comprising at least one selected from Al, Mg, Ca, Ti, Ce, Zn, Y, Hf, Zr, Ba, or Sn, and the mass percentage of the metal element is M%, 0.3 ≤ M ≤ 4%, based on the mass of the first material layer and the positive electrode material layer; The electrolyte comprises a first component, which includes at least one of a compound of formula I-1 or a compound of formula II-1: in, R 11 and R 12 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 11 and R 12 At least one of them has been replaced; R 21 and R 22 Each is independently either substituted or unsubstituted C1-C 10 Alkyl, wherein R 21 and R 22 At least one of them is substituted; when substituted, the substituent is a fluorine atom; Based on the mass of the electrolyte, the mass percentage of the first component is A%, and 40 ≤ A ≤ 85%.

2. The electrochemical device according to claim 1, wherein, The electrolyte includes a second component and / or a third component; The second component includes a compound of formula III: Among them, R 41 R 42 R 43 R 44 Each is independently H, F, substituted or unsubstituted C1-C3 alkyl group, and when substituted, the substituent is a fluorine atom, R. 41 R 42 R 43 R 44 At least one of the components contains F; based on the mass of the electrolyte, the mass percentage of the second component is B%, 5 ≤ B ≤ 15; The third component includes compound I-2: Among them, R 13 R 14 Each independently is C1-C 10 Alkyl group; based on the mass of the electrolyte, the mass percentage of the third component is C%, satisfying: 40 < A + C ≤ 85%.

3. The electrochemical device according to claim 1, wherein, 56≤A≤72。 4. The electrochemical device according to claim 1, wherein, The compound of formula I-1 includes at least one of the following compounds: The compound of formula II-1 includes at least one of the following compounds:

5. The electrochemical device according to claim 2, wherein, The compound of formula III includes at least one of the following compounds:

6. The electrochemical device according to claim 2, wherein, The compound of formula I-2 includes at least one of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, or propyl propionate.

7. The electrochemical device according to any one of claims 1 to 6, wherein, The electrolyte includes a fourth component, which includes at least one of vinylene carbonate, 1,3-propanesulfonyl lactone, succinate, adiponitrile, or 1,3,6-hexanetrionitrile, and the mass percentage of the fourth component is D% based on the mass of the electrolyte, with a mass percentage of 0.1 ≤ D ≤ 6.

8. The electrochemical device according to any one of claims 1 to 6, wherein, The ratio of the length of the first material layer to the length of the positive electrode current collector is X%, and 50 ≤ X ≤ 98.

9. The electrochemical device according to any one of claims 1 to 6, wherein, The ratio of the length of the first material layer to the length of the positive electrode current collector is X%, 80≤X≤98.

10. The electrochemical device according to any one of claims 1 to 6, wherein, The first adhesive comprises a copolymer formed by polymerizing acrylate, acrylamide and acrylonitrile, and the mass percentage of the first adhesive is N%, 2≤N≤10, based on the mass of the first material layer.

11. The electrochemical device according to claim 1, wherein, The inorganic particles include at least one of the following: aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, gibbsite, barium sulfate, calcium sulfate, or calcium silicate; the particle size D of the inorganic particles is... V 50 ranges from 0.3 μm to 1.0 μm.

12. An electronic device comprising the electrochemical device according to any one of claims 1 to 11.

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