Electrolyte, secondary battery, battery module, battery pack and power consumption device

Abstract

An electrolyte for a lithium ion secondary battery and a battery, the electrolyte comprising a solvent, an additive composition, and a lithium salt, the additive composition comprising at least one of the compounds of Formula II and Formula III, and the compound of Formula I. The resulting battery has high voltage and good cycle and storage performance at high temperatures. JPEG2024526449000024.jpg52167

Description

[Technical Field]

[0001] The present application relates to the field of lithium battery technology, and in particular to electrolytes, secondary batteries, battery modules, battery packs and power consuming devices. [Background technology]

[0002] Lithium-ion batteries have become the most popular energy storage system due to their high working potential, long service life, and environmental friendliness, and are now widely applied in fields such as pure electric vehicles, hybrid electric vehicles, smart grids, etc. As people's demand for driving range increases, there is a need to alleviate concerns about the driving range of electric vehicles, and there is an urgent need to develop lithium-ion battery systems with higher energy density.

[0003] In order to improve the energy density of batteries, researchers have prioritized increasing the operating potential of cathode materials. While the operating voltage of conventional ternary cathode materials has been increased to 4.4 V or higher, increasing the voltage significantly reduces the electrolyte's resistance to oxidation, significantly reducing the cell's service life. Conventional electrolytes typically incorporate film-forming additives (e.g., tetravinylsilane) to enhance anode film formation and reduce anode damage caused by by-products generated by cathode oxidation. However, the film formation impedance is too high, significantly worsening the initial battery impedance. Therefore, improvements to conventional electrolyte additives are needed. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and an object thereof is to provide an electrolyte solution for a lithium ion secondary battery and a battery, and the obtained battery has a high voltage and good cycle performance and storage performance at high temperatures.

[0005] In order to achieve the above object, a first aspect of the present application provides an electrolyte solution for a lithium ion secondary battery, comprising a solvent, an additive composition, and a lithium salt, wherein the additive composition comprises at least one of compounds of formula II and formula III and a compound of formula I; [ka] wherein R1, R2, and R3 are each independently H or F, and wherein at least one of R1, R2, and R3 is F; [ka] wherein R4 and R5 are each independently hydrogen, vinyl, allyl, oxyethylene, or oxyallyl, and wherein at least one of R4 and R5 is not H; [ka] Here, R6, R7, R8 and R9 are each independently selected from one or more of an allyl group, a vinyl group and an alkenylbutyl group.

[0006] Therefore, the electrolyte of the present application contains Compound I and Compound II or III, thereby ensuring that the resulting battery has high voltage and good cycle performance and storage performance at high temperature.

[0007] In any embodiment, the compound of formula I is [ka] The compound of formula II is [ka] The compound of formula III is [ka]

[0008] Therefore, the electrolyte of the present application comprises compound I and compound II or III of the above structure, so that the corresponding battery further has high voltage and good cycle performance and storage performance at high temperature.

[0009] In one embodiment, when the content of the compound of formula I in the electrolyte is a% by weight, and the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is b% by weight, 0.05≦a / b≦4.

[0010] Thus, the battery containing the compound I and the compound II or III in the above ratio further has a high voltage and good cycle performance and storage performance at high temperature.

[0011] In one embodiment, when the content of the compound of formula I in the electrolyte is a% by weight, and the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is b% by weight, 0.1≦a+b≦10.

[0012] Thus, the battery containing the compound I and the compound II or III in the above ratio further has a high voltage and good cycle performance and storage performance at high temperature.

[0013] In any embodiment, the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is 0.06 to 8 wt %.

[0014] Thus, the battery containing the compound II or III in the above proportions further has a high voltage and good cycle and storage performance at high temperature.

[0015] In any embodiment, the solvent is an aprotic organic solvent selected from one or more of fluoro and non-fluoro cyclic and linear organic carbonates, fluoro and non-fluoro ethers, fluoro and non-fluoro cyclic ethers, fluoro and non-fluoro carboxylic acid esters, fluoro and non-fluoro linear sulfones, or cyclic sulfone compounds.

[0016] Therefore, the corresponding battery containing the above-mentioned kind of solvent further has high voltage and good cycle performance and storage performance at high temperature.

[0017] In any embodiment, the lithium salt is selected from 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 difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), optionally one or both of lithium hexafluorophosphate or lithium bis(fluorosulfonyl)imide.

[0018] Therefore, the corresponding battery containing the above-mentioned lithium salt further has high voltage and good cycle performance and storage performance at high temperature.

[0019] In any embodiment, the electrolyte solution comprises: The solvent is 60 to 85% by weight, The additive composition is 0.01 to 20% by weight, The lithium salt is 10 to 40% by weight, The total weight of the above components is 100% by weight, and each weight percentage is calculated based on the total weight of the electrolyte.

[0020] Thus, the battery containing each component in the above content has a high voltage and good cycle performance and storage performance at high temperature.

[0021] A second aspect of the present application further provides a secondary battery, the secondary battery comprising: The battery is characterized by containing the electrolyte solution according to the first aspect of the present application.

[0022] Thereby, the battery has a high voltage and good cycle and storage performance at high temperature.

[0023] A third aspect of the present application provides a battery module, which includes the secondary battery of the second aspect of the present application.

[0024] A fourth aspect of the present application provides a battery pack, which includes the battery module of the third aspect of the present application.

[0025] A fifth aspect of the present application provides a power consumption device, which includes at least one selected from the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application.

[0026] The present application provides an electrolyte solution containing Compound I and Compound II or III, thereby ensuring that the resulting battery has high voltage and good cycle and storage performance at high temperature. [Brief explanation of the drawings]

[0027] [Figure 1] 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] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application; [Figure 5] FIG. 5 is an exploded view of the battery pack according to the embodiment of the present application shown in FIG. 4. [Figure 6] 1 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

[0028] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the electrolyte, secondary battery, battery module, battery pack, and electronic device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of actually identical structures may be omitted. This is to avoid the following description becoming unnecessarily long and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0029] The "ranges" disclosed in this application are 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 end values ​​and are combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all contemplated. In this application, unless otherwise specified, the numerical range "ab" represents a shorthand notation for any combination of real numbers from a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the present specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0031] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0032] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and 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.

[0033] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or closed-ended. For example, the terms "comprise" and "include" may further include or include other components not listed, or may include or include only the listed components.

[0034] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0035] In order to improve the energy density of batteries, improving the working potential of cathode materials has become a top priority for researchers. While the working voltage of conventional ternary cathode materials has been increased to 4.4 V or higher, increasing the voltage significantly reduces the electrolyte's resistance to oxidation, significantly reducing the cell's service life. Conventional techniques typically add film-forming additives (e.g., tetravinylsilane) to electrolytes to enhance anode film formation and reduce anode damage caused by by-products generated by cathode oxidation. However, the film-forming impedance is too high, significantly worsening the initial battery impedance. Therefore, improvements to conventional electrolyte additives are needed. This application was made in light of the above-mentioned problems, and its objective is to provide an electrolyte and battery for lithium-ion secondary batteries that have high voltage and good cycle and storage performance at high temperatures.

[0036] Electrolyte for lithium-ion secondary batteries In one embodiment of the present application, the present application provides an electrolyte solution for a lithium ion secondary battery, the electrolyte solution comprising a solvent, an additive composition, and a lithium salt, wherein the additive composition comprises at least one of a compound of Formula II and a compound of Formula III and a compound of Formula I; [ka] wherein R1, R2, and R3 are each independently H or F, and wherein at least one of R1, R2, and R3 is F; [ka] wherein R4 and R5 are each independently hydrogen, vinyl, allyl, oxyethylene, or oxyallyl, and wherein at least one of R4 and R5 is not H; [ka] Here, R6, R7, R8 and R9 are each independently selected from one or more of an allyl group, a vinyl group and an alkenylbutyl group.

[0037] Therefore, the electrolyte solution of the present application contains compound I and compound II or III, so that in the corresponding battery, during the process of forming the anode reduction film, compound II or compound III is preferentially reduced to form a sulfonic acid group-containing radical, which then reacts with compound I to form a polypropylene sulfonate-polypropylene copolymer or polybutylene sulfonate-polypropylene copolymer with an appropriate molecular weight, and further contains inorganic components such as silicate, sulfonate, or lithium salt. The composed SEI film component not only has high ion conductivity, but also has appropriate rigidity and flexibility, can well protect the anode interface, and can resist destruction of the anode SEI film by by-products generated by the subsequent anode oxidation, thereby ensuring that the resulting battery has high voltage and good cycle performance and storage performance at high temperatures.

[0038] In some embodiments, the compound of formula I is [ka] The compound of formula II is [ka] The compound of formula III is [ka]

[0039] Therefore, the electrolyte of the present application comprises compound I and compound II or III of the above structure, so that the corresponding battery further has high voltage and good cycle performance and storage performance at high temperature.

[0040] In some embodiments, when the content of the compound of Formula I in the electrolyte is a% by weight, and the content of the compound of Formula II or the compound of Formula III or a mixture of both in the electrolyte is b% by weight, 0.05≦a / b≦4, preferably 0.05≦a / b≦2, and more preferably 0.5≦a / b≦1.

[0041] Thus, the battery containing the compound I and the compound II or III in the above ratio further has a high voltage and good cycle performance and storage performance at high temperature.

[0042] In some embodiments, when the content of the compound of Formula I in the electrolyte is a% by weight, and the content of the compound of Formula II or the compound of Formula III or a mixture of both in the electrolyte is b% by weight, 0.1≦a+b≦10, preferably 0.1≦a+b≦6.

[0043] Thus, the battery containing the compound I and the compound II or III in the above ratio further has a high voltage and good cycle performance and storage performance at high temperature.

[0044] In some embodiments, the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is 0.06 to 8 wt %, preferably 1 to 8 wt %.

[0045] Thus, the battery containing the compound II or III in the above proportions further has a high voltage and good cycle and storage performance at high temperature.

[0046] In some embodiments, the solvent is an aprotic organic solvent selected from one or more of fluoro and non-fluoro cyclic and linear organic carbonates, fluoro and non-fluoro ethers, fluoro and non-fluoro cyclic ethers, fluoro and non-fluoro carboxylic acid esters, fluoro and non-fluoro linear sulfones or cyclic sulfone compounds, preferably one or more of fluorinated carbonate esters and fluorinated carboxylic acid esters.

[0047] Therefore, the corresponding battery containing the above-mentioned kind of solvent further has high voltage and good cycle performance and storage performance at high temperature.

[0048] In some embodiments, the solvent is further selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0049] In some embodiments, the lithium salt is selected from 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 difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP), optionally one or both of LiPF or LiFSI.

[0050] Therefore, the corresponding battery containing the above-mentioned lithium salt further has high voltage and good cycle performance and storage performance at high temperature.

[0051] In some embodiments, the electrolyte solution comprises: The solvent is present in an amount of 60 to 85% by weight, preferably 80 to 88% by weight, The additive composition is 0.01 to 20% by weight, preferably 0.3 to 15% by weight, The lithium salt is present in an amount of 10 to 40% by weight, preferably 10 to 15% by weight, The total weight of the above components is 100% by weight, and each weight percentage is calculated based on the total weight of the electrolyte.

[0052] Thus, the battery containing each component in the above content has a high voltage and good cycle performance and storage performance at high temperature.

[0053] In some embodiments, the additive composition may further include an anode film-forming additive, a cathode film-forming additive, and may further include an additive 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, such as lithium difluorophosphate (LiPOF), lithium fluoride sulfate (LiSOF), etc. The anode film-forming additive is one or more of vinylene carbonate, fluoroethylene carbonate, and vinyl sulfate.

[0054] A second aspect of the present application further provides a secondary battery, the secondary battery comprising: The battery is characterized by containing the electrolyte solution according to the first aspect of the present application.

[0055] Thereby, the battery has a high voltage and good cycle and storage performance at high temperature.

[0056] The secondary battery, battery module, battery pack and power consumption device of the present application will be described below with appropriate reference to the drawings.

[0057] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging, active ions shuttle between the positive and negative electrodes, absorbing and releasing them. The electrolyte serves to conduct ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily serves to prevent short-circuiting between the positive and negative electrodes while allowing ions to pass through.

[0058] [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, the positive electrode film layer including the positive electrode active material of the first aspect of the present application.

[0059] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two facing surfaces of the positive electrode current collector.

[0060] 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 formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0061] In some embodiments, the positive electrode active material may be any positive electrode active material known in the art for batteries. For example, the positive electrode active material may include at least one of a lithium-containing phosphate having an olivine structure, a lithium transition metal oxide, and a modified compound thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., 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 0.2 O2(NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O2(NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05Examples of the lithium-containing phosphate having an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0062] In some embodiments, the positive electrode membrane layer optionally further includes an adhesive, which may include at least one 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.

[0063] In some embodiments, the positive electrode film layer may further include a conductive agent, for example, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0064] In some embodiments, the positive electrode plate may be manufactured in the following manner: the components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0065] [Negative electrode plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0066] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two facing surfaces of the negative electrode current collector.

[0067] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a 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 formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0068] In some embodiments, the negative electrode active material may be any negative electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may be selected from at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy. The tin-based material may be selected from at least one of a tin element, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative electrode active material may also be used. These negative electrode active materials may be used alone or in combination.

[0069] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, which may be selected from at least one 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).

[0070] In some embodiments, the negative electrode film layer further optionally includes a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0071] In some embodiments, the negative electrode membrane layer optionally further comprises other additives, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

[0072] In some embodiments, the negative electrode plate may be manufactured in the following manner: the components for manufacturing the negative electrode plate, such as the negative electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, and the negative electrode plate is obtained after processes such as drying and cold pressing.

[0073] [Electrolytes] The electrolyte serves to conduct ions between the positive and negative electrodes.

[0074] In some embodiments, the electrolyte is the electrolyte of the first aspect of the present application.

[0075] [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 structure separator having good chemical stability and mechanical stability may be selected.

[0076] In some embodiments, the separator may be made of at least one material selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator is not particularly limited and may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer are not particularly limited and may be the same or different.

[0077] In some embodiments, the positive electrode plate, the negative electrode plate and the separator may be wound or stacked to form an electrode assembly.

[0078] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and electrolyte.

[0079] 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-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0080] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a rectangular secondary battery 5.

[0081] In some embodiments, referring to FIG. 2 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a receiving cavity. The case 51 may have an opening communicating with the receiving cavity, and the cover plate 53 may be installed to cover the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and this can be selected by those skilled in the art according to specific actual needs.

[0082] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art depending on the application and capacity of the battery module.

[0083] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0084] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0085] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, the specific number of which may be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0086] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be provided with a lid on the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0087] The present application also provides a power consuming device, the power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0088] The power consumption device may be a secondary battery, a battery module, or a battery pack, depending on its usage needs.

[0089] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of secondary batteries in the power consuming device, a battery pack or battery module may be employed.

[0090] Other examples of the device may be a mobile phone, a tablet computer, a notebook computer, etc. These devices are generally required to be thin, and may employ a secondary battery as a power source.

[0091] Example In order to make the technical problems, technical solutions, and beneficial effects solved by the present application clearer, 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, and not all of the examples. The following description of at least one exemplary embodiment is merely illustrative in nature and does not constitute any limitation on the present application and its applications. Based on the examples in the present application, all other examples obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0092] Unless specific techniques or conditions are specified in the examples, they are carried out in accordance with the techniques, conditions, or product specifications described in the literature in the field. Unless the manufacturers of the reagents or equipment used are specified, they are all common products available on the market.

[0093] Example 1 1) Manufacturing of positive electrode plates Positive electrode active material: Single crystal particle LiNi with Dv50 of 3.8um 0.5 Mn 0.3 Co 0.2 O2, conductive agent acetylene black, and adhesive polyvinylidene fluoride (PVDF) were dissolved in solvent N-methylpyrrolidone (NMP) in a weight ratio of 96:2:2, and after thorough stirring and uniform mixing, a positive electrode slurry was obtained. The positive electrode slurry was then uniformly coated on a positive electrode current collector, which was then dried, cold pressed, and slit to obtain a positive electrode plate.

[0094] 2) Manufacturing of negative electrode plates Negative electrode active material graphite (BET is 1.2m 3 / g, and D v50 The negative electrode slurry was then uniformly coated on a negative electrode current collector copper foil and dried to obtain a negative electrode film. The negative electrode plate was then cold pressed and slit.

[0095] 3) Separator A common polypropylene film was used as the separator.

[0096] 4) Electrolyte production In a glove box (H2O<0.1 ppm, O2<0.1 ppm) under an argon atmosphere, the organic solvents EC and EMC were mixed uniformly at a volume ratio of 3 / 7, 1M LiPF6 lithium salt was added and dissolved in the organic solvent, 0.5 wt% of tetravinylsilane and 1 wt% of 2-fluoro-1,3-propane sultone based on the weight of the electrolyte were added, and the mixture was stirred uniformly to obtain the corresponding electrolyte.

[0097] 5) Battery manufacturing The positive electrode plate, separator, and negative electrode plate are stacked in this order, with the separator acting as an insulator between the positive and negative electrode plates, and then wound up to obtain an electrode assembly. The electrode assembly is placed in a battery case, dried, and then an electrolyte is injected. The lithium-ion battery is then manufactured through processes such as chemical formation and standing.

[0098] The secondary batteries of Examples 2 to 19 and the secondary batteries of Comparative Examples 1 to 4 are manufactured using methods similar to those of the secondary battery of Example 1, but the compositions and parameters of the additives, solvents, and positive electrode active materials in the electrolyte are adjusted, as shown in Table 1.

[0099] [Table 1] JPEG0007752748000014.jpg205135JPEG0007752748000015.jpg206121

[0100] 2. Battery performance test 1. 25℃ cycle performance test of lithium-ion batteries At 25°C, the lithium-ion battery was charged to 4.45V at a constant current of 0.5C, and then charged at a constant voltage of 4.45V until the current fell below 0.05C. The lithium-ion battery was then discharged to 2.8V at a constant current of 0.5C to obtain the initial discharge capacity C0, which was designated as the first cycle. The number of cycles required for the lithium-ion battery to reach 80% of C0 was calculated.

[0101] 2. 45℃ cycle performance test of lithium-ion batteries At 45°C, the lithium-ion battery was charged to 4.45V at a constant current of 1C, then charged at a constant voltage of 4.45V until the current fell below 0.05C, and then discharged to 2.8V at a constant current of 1C to obtain the initial discharge capacity C0, which was designated as the first cycle. By repeating this charging and discharging process, the number of cycles until the discharge capacity of the lithium-ion battery reached 80% of C0 was calculated.

[0102] 3. 60℃ storage performance test of lithium-ion batteries At 25°C, the lithium-ion battery was charged at a constant current of 0.5C to 4.45V, and then charged at a constant voltage of 4.45V until the current was less than 0.05C. The cell was then stored at 60°C, taken out and fully charged every 10 days, and then stored for a total of 100 days. The corresponding remaining reversible capacity was recorded.

[0103] 3. Test results for each example and comparative example Batteries of each example and comparative example were manufactured according to the above method, and the performance parameters were measured. The results are shown in Table 2 below.

[0104] [Table 2]

[0105] As can be seen from Tables 1 and 2, the electrolyte of the battery of the present invention contains Compound I and Compound II or III, thereby improving the high-temperature cycle life and high-temperature storage performance of the battery.

[0106] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods that are configured by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0107] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 top cover assembly

Claims

1. An electrolyte solution for a lithium ion secondary battery, comprising a solvent, an additive composition, and a lithium salt, wherein the additive composition comprises at least one of a compound of Formula II and a compound of Formula III and a compound of Formula I; 【Chemical 1】 Here, R １ , R ２ and R ３ are each independently H or F, where R １ And, R ２ And, R ３ and at least one of is F; 【Chemistry 2】 Here, R ４ and R ５ are each independently hydrogen, a vinyl group, an allyl group, an oxyethylene group, or an oxyallyl group, where R ４ and R ５ At least one of these is not H, 【Chemistry 3】 Here, R ６ , R ７ , R ８ and R ９ are each independently selected from one or more of an allyl group, a vinyl group, and an alkenylbutyl group; When the content of the compound of formula I in the electrolyte is a% by weight, and the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is b% by weight, An electrolyte solution for a lithium ion secondary battery, characterized in that 0.05≦a / b≦5 and 0.1≦a+b≦12.

2. The compound of formula I is 【Chemistry 4】 The compound of formula II is 【Chemistry 5】 The compound of formula III is 【Chemistry 6】 2. The electrolyte solution according to claim 1 .

3. When the content of the compound of formula I in the electrolyte is a% by weight, and the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is b% by weight, 3. The electrolyte solution according to claim 1, wherein a / b satisfies 0.05≦a / b≦4.

4. When the content of the compound of formula I in the electrolyte is a% by weight, and the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte is b% by weight, 3. The electrolyte solution according to claim 1, wherein 0.1≦a+b≦10.

5. 3. The electrolyte solution according to claim 1, wherein the content of the compound of formula II or the compound of formula III or a mixture of both in the electrolyte solution is 0.06 to 8% by weight.

6. 3. The electrolytic solution according to claim 1, wherein the solvent is an aprotic organic solvent, and the aprotic organic solvent is selected from one or more of fluoro and non-fluoro cyclic and chain organic carbonates, fluoro and non-fluoro ethers, fluoro and non-fluoro cyclic ethers, fluoro and non-fluoro carboxylic acid esters, fluoro and non-fluoro chain sulfones, and cyclic sulfone compounds.

7. 3. The electrolyte solution according to claim 1, wherein the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

8. In the electrolyte, The solvent is 60 to 85% by weight, the additive composition is 0.01 to 20 wt. %; The lithium salt is 10 to 40% by weight, 3. The electrolyte solution according to claim 1, wherein the total weight of the electrolyte solution is 100% by weight, and each weight percentage is calculated based on the total weight of the electrolyte solution.

9. A secondary battery comprising the electrolyte solution according to claim 1.

10. A battery module comprising the secondary battery according to claim 9.

11. A battery pack comprising the battery module according to claim 10.

12. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 9, the battery module according to claim 10, and the battery pack according to claim 11.

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