Electrolyte, secondary battery and power consumption device

Abstract

The present application provides an electrolyte, a secondary battery, and a power consuming device. The electrolyte has the chemical formula R((CH3) m Si) n wherein R comprises at least one of a phosphate group, a phosphite group, a borate group, an amine group, an isocyanate group, a fluorine atom, an oxygen atom, and a sulfur atom; m is 1, 2, or 3; and n is 1, 2, or 3. The incorporation of the first additive into this electrolyte improves the conductivity of the SEI film, which is beneficial for improving lithium ion transport performance. At the same time, the incorporation of the first additive provides good stability to the SEI film and good cycle performance to the battery.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed on September 28, 2023, bearing application number 2023112768425, entitled "Electrolyte, Secondary Battery and Power Consumption Device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of secondary battery technology, and in particular to electrolytes, secondary batteries, and power consuming devices. [Background technology]

[0003] The statements herein merely provide background information related to the present application and may not necessarily constitute prior art.

[0004] During the battery charging process, the solid electrolyte interfacial film (SEI film) formed with the electrolyte affects the battery's cycle performance and lithium ion transport performance. However, in conventional battery performance improvement processes, it is difficult to effectively achieve both cycle performance and lithium ion transport performance. Summary of the Invention [Problem to be solved by the invention]

[0005] For example, to improve the cycling performance of batteries, it is often necessary to improve the stability of the SEI film and reduce interfacial side reactions. However, this adjustment can degrade the lithium ion transport kinetics and slow the charge / discharge rate of the battery. [Means for solving the problem]

[0006] A first aspect of the present application provides an electrolyte, the electrolyte having a chemical formula R((CH3) m Si) nwherein R comprises at least one of a phosphate ester group, a phosphite ester group, a borate ester group, an amine group, an isocyanate group, a fluorine atom, an oxygen atom, and a sulfur atom; m is 1, 2, or 3; and n is 1, 2, or 3.

[0007] The introduction of the first additive into the above-mentioned electrolyte solution can improve the conductivity of the SEI film, which is advantageous for improving the lithium ion transport performance. At the same time, the introduction of the first additive can provide good stability to the SEI film and good cycle performance to the battery. That is, the introduction of the first additive into the electrolyte solution can achieve both good cycle stability and good lithium ion transport performance in the battery.

[0008] In some embodiments, the first additive comprises at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trimethylsilane) borate, trimethylsilyl isocyanate, trimethylfluorosilane, hexamethyldisiloxane, and hexamethyldisilazane.

[0009] In some embodiments, the mass percentage of the first additive in the electrolyte solution is 0.01% to 1%. This range of mass percentage of the first additive in the electrolyte solution allows the first additive to better contribute to the formation of a more stable SEI film, resulting in a battery with a relatively low DCR and good cycle performance. Optionally, the mass percentage of the first additive in the electrolyte solution is 0.05% to 0.5%.

[0010] In some embodiments, the electrolyte further comprises a second additive, the second additive comprising ethylene carbonate. The addition of the second additive can effectively promote dissociation of the electrolyte salt in the electrolyte, improve the conductivity of the electrolyte, and facilitate lithium ion transport. At the same time, the second additive can participate in the SEI film formation process, reduce the occurrence of interfacial side reactions, and improve the cycle performance of the battery.

[0011] In some embodiments, the mass percentage of the second additive in the electrolyte solution is 10% to 40%. When the mass percentage of the second additive in the electrolyte solution is within this range, the electrolyte solution can maintain an appropriate viscosity and high conductivity.

[0012] In some embodiments, the mass ratio of the first additive to the second additive is 0.0001 to 0.05. When the mass ratio of the first additive to the second additive is within this range, the decomposition products of the first additive and the second additive have a good synergistic effect, reducing the DCR of the battery while maintaining better high-temperature cycling performance of the battery. Optionally, the mass ratio of the first additive to the second additive is 0.0003 to 0.03.

[0013] In some embodiments, the electrolyte further includes a third additive, the third additive including at least one of a difluorophosphate and a tetrafluoroborate. The difluorophosphate and the tetrafluoroborate can improve the stability of the SEI film, making the SEI film more tough and more uniform and dense. The difluorophosphate and the tetrafluoroborate can also reduce decomposition of the electrolyte, which is advantageous for improving the cycle performance of the battery. Optionally, the difluorophosphate includes at least one of lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. Optionally, the tetrafluoroborate includes at least one of lithium tetrafluoroborate, sodium tetrafluoroborate, and potassium tetrafluoroborate.

[0014] In some embodiments, the mass percentage of the third additive in the electrolyte solution is 0.01% to 1%. When the mass percentage of the third additive in the electrolyte solution is within this range, the stability of the SEI film can be further improved, and the cycle performance of the battery can be further improved.

[0015] In some embodiments, the mass ratio of the first additive to the third additive is 0.1 to 30. By setting the mass ratio of the first additive to the third additive within this range, the battery can achieve both lower resistance and better high-temperature cycle performance. Optionally, the mass ratio of the first additive to the third additive is 3 to 10.

[0016] In some embodiments, the electrolyte solution further includes a fourth additive, the fourth additive including at least one of vinylene carbonate and vinyl ethylene carbonate. The fourth additive can initiate a radical polymerization reaction on the surface of the negative electrode to generate a lithium polyalkyl carbonate, which is involved in the formation of an SEI film, further improving the flexibility of the SEI film and allowing the SEI film to change with changes in the volume of the negative electrode. This can reduce the risk of the SEI film rupturing and exposing new active sites during cycling, and can also reduce the occurrence of side reactions, thereby improving the cycle life and charge / discharge efficiency of the battery.

[0017] In some embodiments, the mass percentage of the fourth additive in the electrolyte solution is 1% to 5%. When the mass percentage of the fourth additive in the electrolyte solution is within this range, the battery can achieve both lower resistance and better high-temperature cycle performance.

[0018] In some embodiments, the mass ratio of the fourth additive to the total mass of the first additive and the third additive is 0.01 to 0.5. By having the mass ratio of the fourth additive to the total mass of the first additive and the third additive within this range, the battery can achieve both better high-temperature cycle performance and better dynamic performance. Optionally, the mass ratio of the fourth additive to the total mass of the first additive and the third additive is 0.3 to 0.4.

[0019] A second aspect of the present application provides a secondary battery, the secondary battery including a positive electrode plate, a negative electrode plate, a separator, and the electrolyte, the separator being located between the positive electrode plate and the negative electrode plate.

[0020] In some embodiments, the thickness of the separator is 10 μm to 30 μm. By having the thickness of the separator within this range, the separator can have good stability and be less susceptible to puncture, while allowing lithium ions to pass through at a high rate, and further allowing the battery to maintain good high-temperature cycle performance and good lithium ion transmission performance.

[0021] In some embodiments, the porosity of the separator is 20% to 50%. Having a porosity within this range reduces the risk of metal ions eluted from the positive electrode plate passing through the separator and reaching the negative electrode plate during cycling, which is advantageous for reducing side reactions on the surface of the negative electrode plate and maintaining good high-temperature cycling performance in the battery. At the same time, having a porosity within this range allows lithium ions to pass through relatively smoothly, which is advantageous for maintaining good lithium ion transmission performance in the battery.

[0022] A third aspect of the present application provides an electric power consuming device including the electrolyte solution and / or the secondary battery.

[0023] To better describe and explain embodiments or examples according to the present application, reference may be made to one or more drawings. Additional details or examples for describing the drawings should not be considered to limit the scope of either the disclosed application, the presently described embodiments or examples, or the best mode of these applications as currently understood. Note that the same drawing numbers refer to the same elements in all drawings. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Figure 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Figure 3] FIG. 3 is a schematic diagram of a power consumption device powered by a secondary battery according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0025] To facilitate understanding of the present application, the following more fully describes the present application with reference to the associated drawings. The drawings illustrate preferred embodiments of the present application. However, the present application may be embodied in many different forms and is not limited to the embodiments set forth herein. Rather, the purpose of providing these embodiments is to provide a more thorough and complete understanding of the disclosure of the present application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used herein are for the purpose of describing specific examples only and are not intended to be limiting of the present application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0027] The "ranges" disclosed herein may be defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the endpoints, and any endpoint may be independently inclusive or exclusive, and any combination is possible; i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are further listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range of "a to b" represents a shorthand representation of any combination of real numbers a to b, where a and b are both real numbers. For example, a numerical range of "0 to 5" represents that all real numbers between "0 and 5" have already been listed in this specification, and "0 to 5" is merely a shorthand representation of these combinations. Furthermore, expressing a parameter as an integer ≧2 is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, expressing a parameter as an integer selected from "2 to 10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0028] As used herein, unless otherwise limited, the terms "plurality," "multiple," and the like refer to a number greater than or equal to two. For example, "one or more" refers to one or more than two.

[0029] Unless otherwise stated, all embodiments and optional embodiments in this application can be combined with each other to form a new technical solution.

[0030] An "embodiment" referred to in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment or embodiment of the present application. The appearances of this phrase in various locations in the specification do not necessarily all refer to the same embodiment, nor are they mutually exclusive independent or alternative embodiments of other embodiments. Those skilled in the art can explicitly and implicitly understand that the embodiments described in this specification can be combined with other embodiments. The term "embodiment" referred to in this specification has a similar meaning.

[0031] As will be understood by those skilled in the art, in the methods of the embodiments or examples, the order of steps described does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of steps should be determined by their functions and possible underlying logic. Unless otherwise specified, all steps in this application may be performed sequentially or randomly, and in some examples, are performed sequentially. For example, when a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, when a method described above may further include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0032] In this application, open technical features or technical solutions described with words such as "comprise," "include," or "comprise" do not exclude additional members other than the enumerated members, unless otherwise specified, and can be considered to provide not only a closed feature or solution consisting of the enumerated members, but also an open feature or solution including additional members in addition to the enumerated members. For example, when A includes a1, a2, and a3, unless otherwise specified, it may further include other members or may not include additional members, and can be considered to provide not only a feature or solution in which "A is composed of a1, a2, and a3," but also a feature or solution in which "A not only includes a1, a2, and a3, but also includes other members."

[0033] In this application, unless otherwise specified, it can be understood that A (for example, B) means that B represents one non-limiting example of A, and that A is not limited to B.

[0034] In this application, "optionally", "optional" and "optionally" refer to the possibility of being present or absent, that is, to selecting one of the two parallel solutions of "present" or "absent". When "optionally" appears in multiple places in a technical solution, unless otherwise specified and unless there is a contradictory or mutually restrictive relationship, the "option" in each clause is independent.

[0035] One embodiment of the present application provides an electrolyte solution, the electrolyte solution having a chemical formula of R((CH3) m Si) nwherein R comprises at least one of a phosphate ester group, a phosphite ester group, a borate ester group, an amine group, an isocyanate group, a fluorine atom, an oxygen atom, and a sulfur atom; m is 1, 2, or 3; and n is 1, 2, or 3. The incorporation of the first additive into this electrolyte solution can improve the conductivity of the SEI film, which is advantageous for improving lithium ion transport performance. At the same time, the incorporation of the first additive can impart good stability to the SEI film and further impart good cycle performance to the battery. That is, the incorporation of the first additive into the electrolyte solution can achieve both good cycle stability and good lithium ion transport performance in the battery.

[0036] In some embodiments, m=3. The formula of the first additive is R((CH3)3Si). n During the battery charging process, this first additive is more likely to participate in the film formation process of the SEI film, reducing the direct current resistance (DCR) of the battery and further improving the lithium ion transport performance.

[0037] In some embodiments, R comprises at least one of a phosphite group, a borate group, an amine group, an isocyanate group, an oxygen atom, and a sulfur atom, and the corresponding first additive can effectively alleviate the gas generation problem of the battery during the cycling process of the battery, and further improve the cycling performance of the battery.

[0038] In some embodiments, the first additive is [ka] It includes at least one of the following.

[0039] In some embodiments, the first additive comprises at least one of tris(trimethylsilane) phosphate ester and trimethylfluorosilane. In this case, by selecting the first additive from tris(trimethylsilane) phosphate ester and trimethylfluorosilane, the DCR of the battery can be more effectively reduced and the initial power performance of the battery can be improved.

[0040] In some embodiments, the first additive comprises at least one of tris(trimethylsilane) phosphite, tris(trimethylsilane) borate, hexamethyldisiloxane, and hexamethyldisilazane. In this case, selecting the first additive from tris(trimethylsilane) phosphite, tris(trimethylsilane) borate, hexamethyldisiloxane, and hexamethyldisilazane can effectively alleviate the gas generation problem during battery cycling and is advantageous for improving the internal structural stability of the battery.

[0041] In some embodiments, the mass percentage of the first additive in the electrolyte is 0.01% to 1%. This range of mass percentage of the first additive in the electrolyte allows for better formation of a more stable SEI film, resulting in a battery with a relatively low DCR and good cycling performance. Alternatively, the mass percentage of the first additive in the electrolyte is 0.05% to 0.5%. More preferably, the mass percentage of the first additive in the electrolyte may be 0.01%, 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or the like.

[0042] In some embodiments, the electrolyte further comprises a second additive, the second additive comprising ethylene carbonate. The addition of the second additive can effectively promote dissociation of the electrolyte salt in the electrolyte, improve the conductivity of the electrolyte, and facilitate lithium ion transport. At the same time, the second additive can participate in the SEI film formation process, reduce the occurrence of interfacial side reactions, and improve the cycle performance of the battery.

[0043] Alternatively, the mass percentage of the second additive in the electrolyte is 10% to 40%. By having the mass percentage of the second additive in the electrolyte within this range, the electrolyte can maintain an appropriate viscosity and high conductivity. Furthermore, the mass percentage of the second additive in the electrolyte can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0044] In some embodiments, the mass ratio of the first additive to the second additive is 0.0001 to 0.05. When the mass ratio of the first additive to the second additive is within this range, the decomposition products of the first additive and the second additive have a good synergistic effect, which can reduce the DCR of the battery while maintaining better high-temperature cycling performance of the battery. Optionally, the mass ratio of the first additive to the second additive is 0.0003 to 0.03. More optionally, the mass ratio of the first additive to the second additive may be 0.0005, 0.001, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, etc.

[0045] In some embodiments, the electrolyte further includes a third additive, and the third additive includes at least one of a difluorophosphate and a tetrafluoroborate. The difluorophosphate and the tetrafluoroborate can improve the stability of the SEI film, making the SEI film more tough and more uniform and dense. The difluorophosphate and the tetrafluoroborate can also reduce decomposition of the electrolyte, which is advantageous for improving the cycle performance of the battery. Optionally, the difluorophosphate includes at least one of lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate. The tetrafluoroborate includes at least one of lithium tetrafluoroborate, sodium tetrafluoroborate, and potassium tetrafluoroborate.

[0046] In some embodiments, the mass percentage of the third additive in the electrolyte solution is 0.01% to 1%. By having the mass percentage of the third additive in the electrolyte solution within this range, the stability of the SEI film can be further improved, and the cycle performance of the battery can be further improved. Optionally, the mass percentage of the third additive in the electrolyte solution can be 0.01%, 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0047] In some embodiments, the mass ratio of the first additive to the third additive is 0.1 to 30. By having the mass ratio of the first additive to the third additive within this range, the battery can achieve both lower resistance and better high-temperature cycling performance. Optionally, the mass ratio of the first additive to the third additive is 3 to 10. More optionally, the mass ratio of the first additive to the third additive may be 0.1, 0.5, 0.8, 1, 5, 8, 10, 15, 20, 25, 30, etc.

[0048] In some embodiments, the electrolyte solution further includes a fourth additive, the fourth additive including at least one of vinylene carbonate (VC) and vinyl ethylene carbonate (VEC). The fourth additive can initiate a radical polymerization reaction on the surface of the negative electrode, producing a lithium polyalkyl carbonate to participate in the formation of an SEI film, further improving the flexibility of the SEI film and allowing the SEI film to change with changes in the volume of the negative electrode. This can reduce the risk of the SEI film rupturing and exposing new active sites during cycling, and can also reduce the occurrence of side reactions, thereby improving the cycle life and charge / discharge efficiency of the battery.

[0049] Alternatively, the mass percentage of the fourth additive in the electrolyte is 1% to 5%. By having the mass percentage of the fourth additive in the electrolyte within this range, the battery can achieve both lower resistance and better high-temperature cycle performance. Alternatively, the mass percentage of the fourth additive in the electrolyte is 1% to 3%. More preferably, the mass percentage of the fourth additive in the electrolyte may be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0050] In some embodiments, the mass ratio of the fourth additive to the total mass of the first additive and the third additive is 0.01 to 0.5. By having the mass ratio of the fourth additive to the total mass of the first additive and the third additive within this range, the battery can achieve both better high-temperature cycling performance and better dynamic performance. Optionally, the mass ratio of the fourth additive to the total mass of the first additive and the third additive is 0.3 to 0.4. More optionally, the mass ratio of the fourth additive to the total mass of the first additive and the third additive may be 0.01, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0051] In some embodiments, the electrolyte solution further comprises an electrolyte salt and a solvent.

[0052] Optionally, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPOF), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0053] Optionally, the solvent is [ka] Ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), [ka] The solvent may include one or more of fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0054] Optionally, the electrolyte solution may further optionally contain other additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, or an additive that improves the high-temperature or low-temperature performance of the battery.

[0055] Optionally, other additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0056] In yet another embodiment of the present application, there is provided a secondary battery, the secondary battery comprising a positive electrode plate, a negative electrode plate, a separator, and the above-mentioned electrolyte, the separator being located between the positive electrode plate and the negative electrode plate, and the application of the above-mentioned electrolyte to the battery can achieve both good cycle performance and good lithium ion transport performance.

[0057] In some embodiments, the thickness of the separator is 10 micrometers (μm) to 30 μm. Having a thickness within this range allows the separator to have good stability and be puncture-resistant, while allowing lithium ions to pass through at a high rate, and further allows the battery to maintain good high-temperature cycling performance and good lithium ion transmission performance. Optionally, the thickness of the separator may be 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, etc.

[0058] In some embodiments, the porosity of the separator is 20% to 50%. Having a porosity within this range reduces the risk of metal ions eluted from the positive electrode plate passing through the separator and reaching the negative electrode plate during cycling, which is advantageous for reducing side reactions on the surface of the negative electrode plate and maintaining good high-temperature cycling performance in the battery. At the same time, having a porosity within this range allows lithium ions to pass through relatively smoothly, which is advantageous for maintaining good lithium ion transmission performance in the battery.

[0059] Yet another embodiment of the present application provides a power consuming device including the above electrolyte and / or the above secondary battery.

[0060] The secondary battery and power consuming device of the present application will now be described with appropriate reference to the drawings.

[0061] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions move back and forth between the positive electrode plate and the negative electrode plate to absorb and release them. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator, installed between the positive electrode plate and the negative electrode plate, serves mainly to prevent short-circuiting between the positive and negative electrodes and allows ions to pass through.

[0062] positive electrode plate The positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0063] As a non-limiting example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode active material layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0064] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be obtained by forming a metal material on a polymer substrate. Non-limiting examples of the metal material in the positive electrode current collector may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. Non-limiting examples of the polymer substrate in the positive electrode current collector may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0065] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. Non-limiting examples of the positive electrode active material include one or more of the following: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of the lithium transition metal oxide include, but are not limited to, lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and modified compounds thereof. Non-limiting examples of lithium-containing phosphates of the olivine structure may include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composite, lithium manganese phosphate, lithium manganese phosphate and carbon composite, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composite, and modified compounds thereof. Non-limiting examples of lithium cobalt oxides may include LiCoO2, non-limiting examples of lithium nickel oxides may include LiNiO2, non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc., and non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 A non-limiting example of lithium nickel cobalt aluminum oxide is LiNi 0.8 Co 0.15 Al 0.05 May contain O2.

[0066] In some embodiments, the positive electrode active material layer may further include an adhesive. Non-limiting examples of the adhesive include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0067] In some embodiments, the positive electrode active material layer may further include a conductive agent, and the conductive agent may include, by way of non-limiting example, one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0068] In some embodiments, a positive electrode plate can be manufactured in the following manner. Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent to form a positive electrode slurry. The positive electrode slurry is then applied to at least one surface of a positive electrode current collector, followed by drying, cold pressing, and other processes to obtain a positive electrode plate. The type of solvent may be selected from any one of the above-described embodiments, such as, but not limited to, N-methylpyrrolidone (NMP). The surface of the positive electrode current collector to which the positive electrode slurry is applied may be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The surface of the positive electrode current collector to which the positive electrode slurry is applied may be a single surface of the positive electrode current collector or two surfaces of the positive electrode current collector. The solid content of the positive electrode slurry may be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted from 5,000 millipascals per second (mPa·s) to 25,000 mPa·s. When applying the positive electrode slurry, the applied area density (excluding the solvent) is 15 milligrams per square centimeter (mg / cm). 2 )~35mg / cm 2 The positive electrode plate may have a compacted density of 3.0 grams per cubic centimeter (g / cm 3 )~3.6g / cm 3 and optionally 3.3 g / cm 3 ~3.5g / cm 3 may be.

[0069] Negative electrode plate The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

[0070] As a non-limiting example, the negative electrode current collector has two surfaces facing each other in the thickness direction thereof, and the negative electrode active material layer is disposed on one or both of the two facing surfaces of the negative electrode current collector.

[0071] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be obtained by forming a metal material on a polymer substrate. Non-limiting examples of the metal material in the negative electrode current collector may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. Non-limiting examples of the polymer substrate in the negative electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0072] In some embodiments, the negative electrode active material may be a battery negative electrode active material known in the art. Non-limiting examples of the negative electrode active material include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include one or more of silicon elemental, silicon oxide compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. Tin-based materials may include one or more of tin elemental, stannate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0073] In some embodiments thereof, the negative electrode active material layer optionally further includes an adhesive, which may include one or more of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0074] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0075] In some of the embodiments, the negative electrode active material layer optionally further contains other additives, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0076] In some embodiments, a negative electrode plate can be manufactured in the following manner. Components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (non-limiting examples of which include deionized water) to form a negative electrode slurry. The negative electrode slurry is then applied to at least one surface of a negative electrode current collector, followed by processes such as drying and cold pressing to obtain a negative electrode plate. The surface of the negative electrode current collector to which the negative electrode slurry is applied may be a single surface of the negative electrode current collector, or may be two surfaces of the negative electrode current collector. The solid content of the negative electrode slurry may be 40 wt% to 60 wt%. The viscosity of the negative electrode slurry at room temperature may be adjusted to 2000 mPa·s to 10000 mPa·s. When the negative electrode slurry is applied, the application unit area density (excluding the solvent) is 75 grams per square meter (g / m) on a dry weight basis. 2 )~220g / m 2 The negative electrode plate may have a compaction density of 1.0 g / cm 3 ~1.8g / cm 3 may be.

[0077] electrolyte The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not particularly limit the type of electrolyte, and it may be selected according to needs. For example, the electrolyte may be liquid, gel, or all-solid.

[0078] In some embodiments, the electrolyte is an electrolytic solution. Optionally, the electrolytic solution may be selected from the electrolytic solutions of the present application.

[0079] Separator In some embodiments, the secondary battery further includes a separator. The present application does not particularly limit the type of separator, and any known porous separator with good chemical stability and mechanical stability may be selected.

[0080] In some embodiments, the separator may be made of one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, without any particular limitation.

[0081] In some embodiments, the thickness of the separator is between 6 μm and 40 μm, and optionally between 12 μm and 20 μm.

[0082] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be wound or stacked to form an electrode assembly.

[0083] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0084] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-like pouch. The material of the pouch may be plastic, and non-limiting examples of the plastic may include one or more of polypropylene, polybutylene terephthalate, polybutylene succinate, etc.

[0085] A secondary battery includes at least one battery cell, and may include one or more battery cells.

[0086] In this application, unless otherwise specified, the term "battery cell" refers to a basic unit capable of converting chemical energy into electrical energy and vice versa, and generally includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the charge and discharge process of a battery, active ions are absorbed and released by shuttle movement between the positive and negative electrodes. The electrolyte serves to conduct the active ions between the positive and negative electrodes.

[0087] The present application does not particularly limit the shape of the battery cell, which may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows a secondary battery 1 having a rectangular structure as an example.

[0088] In some embodiments, referring to FIG. 2 , the exterior body may include a case 11 and a cover plate 13. Here, the case 11 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate together form a surrounding accommodating cavity. The case 11 has an opening communicating with the accommodating cavity, and the cover plate 13 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 12 through a winding process or a stacking process. The electrode assembly 12 is packaged within the accommodating cavity. An electrolyte is impregnated into the electrode assembly 12. The number of electrode assemblies 12 included in the secondary battery 1 may be one or more, and those skilled in the art can select the number according to actual needs.

[0089] The secondary battery may be a battery module or a battery pack.

[0090] The battery module includes at least one battery cell. The number of battery cells included in the battery module may be one or more, and those skilled in the art may select an appropriate number according to the application and capacity of the battery module.

[0091] In the battery module, the battery cells may be arranged in a row along the longitudinal direction of the battery module, or may be arranged in any other manner. Furthermore, the battery cells may be fastened together by fasteners.

[0092] Optionally, the battery module may further include a housing having an accommodating space, and the plurality of battery cells are accommodated in the accommodating space.

[0093] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and those skilled in the art can select an appropriate number depending on the application and capacity of the battery pack.

[0094] The battery pack may include a battery box and a plurality of battery modules installed in the battery box. The battery box includes an upper housing and a lower housing, and the upper housing can be covered by a lid to form a sealed space for accommodating the battery modules. The plurality of battery modules may be arranged in the battery box in any manner.

[0095] The present application also provides a power consuming device including a secondary battery according to the present application. The secondary battery can be a power source for the power consuming device and can also be an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, a mobile device, an electric vehicle, an electric train, a ship, a satellite, an energy storage system, etc. Here, the mobile device may be, for example, a mobile phone, a laptop, etc., and the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited to these.

[0096] A secondary battery may be selected as the power consuming device depending on its usage demand.

[0097] 3 shows an example of a power consumption device 2. The power consumption device may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the demand for high power output and high energy density of the secondary battery of the power consumption device, a battery pack or a battery module may be employed.

[0098] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0099] In order to clarify the technical problems, technical solutions and advantageous effects that the present application aims to solve, the present application will be described in more detail below in conjunction with examples and drawings. Obviously, the described examples are only some of the examples of the present application, but not all of the examples. The following description of at least one exemplary embodiment is merely illustrative in nature and is not intended to impose any limitations on the present application and its applications. All other embodiments obtained by those skilled in the art based on the examples in the present application without the need for creative efforts fall within the scope of protection of the present application.

[0100] Unless specific techniques or conditions are specified in the examples, they are performed according to the techniques or conditions described in the literature or in accordance with the product instructions. Unless the manufacturer is specified, reagents or equipment used are all commercially available products. [Example]

[0101] Example 1 (1) Manufacturing of positive electrode plates. Lithium iron phosphate positive electrode material, polyvinylidene fluoride (PVDF), and carbon black (SP) were mixed with NMP solvent in a mass ratio of 97:2:1, and stirred to obtain a uniformly dispersed positive electrode slurry. The positive electrode slurry was then evenly applied to two surfaces of aluminum foil, dried, cold pressed, and cut to obtain a positive electrode plate.

[0102] (2) Manufacturing of negative electrode plates. Artificial graphite, carbon black, styrene butadiene rubber, and sodium carboxymethyl cellulose were mixed with water in a mass ratio of 97:0.5:1.5:1, and stirred to obtain a uniformly dispersed negative electrode slurry. The negative electrode slurry was then uniformly applied to two surfaces of copper foil, which was then dried, cold-pressed, and cut to obtain a negative electrode plate.

[0103] (3) A polyethylene film is used as the separator. The thickness and porosity of the separator are shown in Table 1.

[0104] (4) The composition of the electrolyte is shown in Table 1.

[0105] (5) Manufacture of secondary batteries. The positive electrode plate, negative electrode plate, and separator were wound into an electrode assembly, which was then placed in a housing made of an aluminum case, an aluminum plastic film, or the like. The electrolyte was then poured into the assembly, which was then left to stand at high temperature for chemical formation and volume division, after which a secondary battery was obtained.

[0106] The difference between Examples 2 to 20 and Comparative Examples 1 to 4 and Example 1 is the composition of the electrolyte solution, as shown in Table 1.

[0107] Test Example (1) Measurement of high temperature cycle performance at 60 degrees Celsius (°C). At 60°C, the batteries of each example and comparative example were charged at a constant current of 0.5 C until the upper voltage limit reached 3.8 volts (V), and then charged at a constant voltage of 0.05 C. The batteries were then left to stand for 5 minutes and discharged at a constant current of 1 / 3 C to 2.0 V. This was the first charge / discharge cycle of the battery, and the discharge capacity at this time was designated as the discharge capacity D1 of the first cycle of the battery. A cycle charge / discharge test was performed on the batteries according to the above method, and the capacity Dn at the nth cycle of the battery was recorded. The capacity retention rate was Dn / D1. The number of cycles at which the capacity retention rate reached 80% was recorded. The results are shown in Table 1.

[0108] (2) DCR test. At 25°C, the batteries of each example and comparative example were charged at a constant current of 0.5C up to a voltage limit of 3.8V, and then charged at a constant voltage of 0.05C. The batteries were then discharged at 0.5C for 1 hour to adjust the SOC to 50%, and the voltage at this time was recorded as U1. The batteries were then discharged at 4C for 30 seconds, and the voltage at this time was recorded as U2. DCR = (U1 - U2) / 4C. The results are shown in Table 1. Lithium-ion transmission performance can be expressed by DCR.

[0109] (3) Gas generation test. The gas generation rate of a battery can be expressed as the battery's expansion rate. The batteries of each example and comparative example were charged to 3.8 V at a constant current of 0.1 C, and then charged at a constant voltage of 3.8 V until the current was ≦0.05 C. At this point, the battery was already fully charged, and the battery volume V1 was measured using the drainage method. The fully charged batteries were then stored at 60°C. After 30 days, the batteries were removed and allowed to stand at 25°C for 2 hours (h), and the battery volume V2 was measured using the drainage method. The gas generation rate of the battery = (V2 - V1) / V1 × 100%. The results are shown in Table 1.

[0110] [Table 1-1] [Table 1-2] [Table 1-3]

[0111] In Table 1, w1 represents the mass percentage of the first additive in the electrolyte solution. w2 represents the mass percentage of the second additive in the electrolyte solution. w3 represents the mass percentage of the third additive in the electrolyte solution. w4 represents the mass percentage of the fourth additive in the electrolyte solution. w5 represents the mass percentage of the electrolyte salt in the electrolyte solution. A / C represents the mass ratio of the first additive to the second additive. A / B represents the mass ratio of the first additive to the third additive. (A+B) / D represents the mass ratio of the fourth additive to the total mass of the first additive and the third additive. The unit of the separator thickness is μm. The unit of DCR is mΩ.

[0112] As can be seen from Table 1, when the first additive is contained in the electrolyte, the battery can achieve both good cycle performance and good lithium ion transmission performance.

[0113] Furthermore, compared with TMSP and TMSF, when TMSB, TMSPi, HMDSO, HDMS, and trimethylsilyl isocyanate are used as the first additive, the battery has a slightly higher DCR, but the battery has a relatively low gas generation rate, which is advantageous for improving the structural stability inside the battery.

[0114] The technical features of the embodiments described above can be combined in any combination. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered within the scope of the present specification.

[0115] The above-described examples only show some embodiments of the present application, and although the description is more specific and detailed, it should not be understood as limiting the scope of the invention patent. It should be noted that those skilled in the art may make some modifications and improvements without departing from the concept of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application patent shall be governed by the scope of the attached claims. [Explanation of symbols]

[0116] 1...Secondary battery 11. Case 12. Electrode assembly 13 Cover plate 2...Power consumption device

Claims

1. An electrolyte having the chemical formula R((CH ３ ) ｍ Si) ｎ wherein R comprises at least one of a phosphate ester group, a phosphite ester group, a borate ester group, an amine group, an isocyanate group, a fluorine atom, an oxygen atom, and a sulfur atom; m is 1, 2, or 3; and n is 1, 2, or 3.

2. 2. The electrolyte solution of claim 1, wherein the first additive comprises at least one of tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trimethylsilane) borate, trimethylsilyl isocyanate, trimethylfluorosilane, hexamethyldisiloxane, and hexamethyldisilazane.

3. 3. The electrolyte according to claim 1, wherein the mass percentage of the first additive in the electrolyte is 0.01% to 1%, and optionally 0.05% to 0.5%.

4. 4. The electrolyte solution according to claim 1, further comprising a second additive, wherein the second additive comprises ethylene carbonate.

5. 5. The electrolyte solution according to claim 4, wherein the mass percentage of the second additive in the electrolyte solution is 10% to 40%.

6. 6. The electrolyte solution according to claim 4 or 5, wherein the mass ratio of the first additive to the second additive is 0.0001 to 0.05, and optionally 0.0003 to 0.

03.

7. the electrolyte solution further includes a third additive, the third additive including at least one of a difluorophosphate and a tetrafluoroborate; Optionally, the difluorophosphate salt comprises at least one of lithium difluorophosphate, sodium difluorophosphate, and potassium difluorophosphate; Optionally, the tetrafluoroborate salt comprises at least one of lithium tetrafluoroborate, sodium tetrafluoroborate, and potassium tetrafluoroborate; Optionally, the mass percentage of the third additive in the electrolyte solution is 0.01% to 1%.

8. 8. The electrolyte solution according to claim 7, wherein the mass ratio of the first additive to the third additive is 0.1 to 30, and optionally 3 to 10.

9. 9. The electrolyte solution according to claim 7, further comprising a fourth additive, wherein the fourth additive comprises at least one of vinylene carbonate and vinyl ethylene carbonate.

10. 10. The electrolyte solution according to claim 9, wherein the mass percentage of the fourth additive in the electrolyte solution is 1% to 5%.

11. The mass ratio of the total mass of the first additive and the third additive to the fourth additive is 0.01 to 0.5, optionally 0.3 to 0.

4. The electrolyte solution according to claim 9 or 10.

12. 12. A secondary battery comprising a positive electrode plate, a negative electrode plate, a separator, and the electrolyte solution according to claim 1, wherein the separator is located between the positive electrode plate and the negative electrode plate.

13. 13. The secondary battery according to claim 12, wherein the separator has a thickness of 10 μm to 30 μm and / or a porosity of the separator of 20% to 50%.

14. 14. An electric power consuming device comprising an electrolytic solution according to any one of claims 1 to 11 and / or a secondary battery according to any one of claims 12 to 13.

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