Electrolytes, lithium-ion batteries and electrical equipment

Abstract

The present application provides an electrolyte for a lithium ion battery, and by limiting the mixing of a cyclic ether and a lithium salt in the electrolyte for a lithium ion battery, the electrolyte containing both the cyclic ether and the lithium salt has good electrical conductivity, oxidation resistance, system stability, and appropriate viscosity, and can improve the electrical conductivity of the negative electrode interfacial film, thereby significantly improving the high-temperature storage performance, high-temperature cycle performance, and power performance of a lithium ion battery containing the same.

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium batteries, and in particular to electrolytes, lithium-ion batteries, battery modules, battery packs, and electrical equipment. [Background technology]

[0002] In recent years, as the uses of lithium-ion batteries have become more diverse, they are now widely used in a variety of fields, including energy storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aviation, and space.

[0003] However, when a lithium-ion battery is installed in the above-mentioned electrical equipment, the actual operating temperature of the battery is higher due to the limited installation space and the influence of heat dissipation from other components of the electrical equipment. Therefore, simply improving the cycle performance and storage performance of the battery at room temperature cannot effectively improve the actual cycle performance and storage performance of the battery in the electrical equipment. Therefore, the development and design of a lithium-ion battery with excellent high-temperature cycle performance is of great practical value. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application has been made in view of the above-mentioned problems, and provides an electrolyte that effectively improves the high-temperature storage performance and high-temperature cycle performance of a battery, as well as a lithium-ion battery, a battery module, a battery pack, and electrical equipment that include the electrolyte of the present application. [Means for solving the problem]

[0005] To achieve the above object, a first aspect of the present application provides an electrolyte solution, the electrolyte solution including an electrolyte salt and an organic solvent, the electrolyte salt including a lithium salt, and the organic solvent including a cyclic ene vinegar a mass fraction of the lithium salt relative to the electrolyte solution is W1; vinegar When the mass fraction of the terbium is W2, the relationship 0.2≦W1 / W2≦1.06 is satisfied.

[0006] In an optional embodiment, in the electrolyte solution of the present application, the range of W1 / W2 is 0.5 to 1.06, and optionally 0.8 to 1.0.

[0007] In any embodiment, in the electrolyte solution of the present application, the ratio of the cyclic ene to the mass of the organic solvent is vinegar The mass fraction B of the mass of the ter is 5% to 18%, optionally 13% to 16%.

[0008] In an optional embodiment, in the electrolyte solution of the present application, the lithium salt includes at least one of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the cyclic ene vinegar The terephthalate includes at least one of ethylene carbonate and propylene carbonate.

[0009] In any embodiment, in the electrolyte solution of the present application, the sum of the molar concentration C1 of the lithium bis(fluorosulfonyl)imide and the molar concentration C2 of the lithium hexafluorophosphate is 0.86 to 1.4M.

[0010] In an optional embodiment, the electrolyte solution of the present application includes a film-forming additive, and the mass fraction of the film-forming additive relative to the electrolyte solution is A, and the mass fraction of the cyclic ene relative to the electrolyte solution is A. vinegar When the mass fraction of the terbium is W2, the relationship 10≦W2 / 5+2×A≦16 is satisfied.

[0011] A second aspect of the present application provides a lithium-ion battery including the electrolyte of the first aspect of the present application, a separator, a negative electrode plate, and a positive electrode plate.

[0012] In any embodiment, the positive electrode plate comprises LiNi as a positive electrode active material. x Co y Mn z The cyclic oxygen containing oxygen is vinegarWhen the mass fraction of the nickel is W2 and the content of the nickel atoms is x, the relationship 0.5≦W2 / (100x)≦0.72 is satisfied, with the proviso that x+y+z=1 is satisfied.

[0013] In any embodiment, the positive electrode plate comprises LiNi as a positive electrode active material. x Co y Mn z O2, and in consideration of the electrolyte of the present application, the content x of nickel atoms is 0.5 or more, and optionally 0.65, 0.8, 0.96, with the proviso that x+y+z=1.

[0014] In any embodiment, in the lithium ion battery of the present application, 1540.25 mm of negative electrode material 2 The amount of the cyclic ene relative to the electrolyte is defined as H. vinegar When the mass fraction of ter is W2, the relationship 20≦W2 / H≦166 is satisfied. [Effects of the Invention]

[0015] The present application provides a method for limiting the mixing of a cyclic ester and a lithium salt in an electrolyte solution for a lithium ion battery, so that the electrolyte solution containing both the cyclic ester and the lithium salt has good electrical conductivity, oxidation resistance, system stability, and appropriate viscosity, thereby improving the electrical conductivity of the negative electrode interfacial film. That This significantly improves the high-temperature storage performance, high-temperature cycle performance, and power performance of lithium-ion batteries that contain it. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a lithium-ion battery according to one embodiment of the present application. [Figure 2] FIG. 2 is an exploded view of the lithium ion battery according to one embodiment of the present application shown in FIG. [Figure 3] FIG. 3 is a schematic diagram of an electrical installation powered by a lithium ion battery according to one embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the electrolyte, lithium ion battery, battery module, battery pack, and electrical device of the present application will be described in detail with reference to the drawings. Note that unnecessary descriptions will be omitted. For example, detailed descriptions of well-known technologies or descriptions of identical structures may be omitted. This is to avoid the description being unintelligible and to facilitate a clear understanding by those skilled in the art. Furthermore, the drawings and the following description are merely intended to facilitate a clear understanding of the present application by those skilled in the art, and are not intended to limit the scope of the claims.

[0018] The "ranges" disclosed in the present invention are defined by lower and upper limits. A given range is defined by selecting lower and upper limits. The selected lower and upper limits define the limits of the particular range. A range defined in this manner may include or exclude the limit values, and is any combination thereof. That is, a range can be defined by combining any lower limit with any upper limit. For example, if ranges of 60 to 120 and 80 to 110 are specified for a particular parameter, it should be understood that ranges of 60 to 110 and 80 to 120 are also predictable. Furthermore, if the lower limits are 1 and 2 and the upper limits are 3, 4, and 5, it should be understood that any of the ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are also predictable. In this application, unless otherwise specified, the numerical range "a to b" is shorthand for any combination of real numbers between the real numbers a and b. For example, the numerical range "0 to 5" includes all real numbers between "0 and 5" as described in the specification, and "0 to 5" is simply a shorthand representation of a combination of these numerical values. Also, when a parameter is expressed as an integer of 2 or more, it means that the integers are, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0019] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined to form a new technical solution.

[0020] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form a new technical solution.

[0021] Unless otherwise specified, all steps in this application may be performed in sequence or randomly. Sequential execution is preferred. For example, if a method includes steps (a) and (b), the method may be performed in the sequence of steps (a) and (b), or in the sequence of steps (b) and (a). For example, the method may further include step (c). In this case, step (c) can be optionally added to the method, and may be performed in the sequence of steps (a), (b), and (c), or in the sequence of steps (a), (c), and (b), or in the sequence of steps (c), (a), and (b).

[0022] Unless otherwise specified, the use of "comprises" and "containing" in this application can be interpreted in either an open-ended or closed-ended manner. For example, "comprises" and "including" can be interpreted as including or containing other compositions not listed, or as including or containing only the listed compositions.

[0023] Unless otherwise specified, the use of the term "or" in this application has a broad meaning. For example, the phrase "A or B" means "A, B, or A and B." More specifically, the condition "A or B" is met when A exists (or is present) and B does not exist (or is absent), when A does not exist (or is absent) and B exists (or is present), or when both A and B exist (or are present).

[0024] Based on the experience in preparing electrolytes, the inventors of the present application have vinegarThey found that adding ether-based solvents to the electrolyte of lithium-ion batteries significantly increases the dissociation of lithium salts, improving the overall conductivity of the electrolyte. They also improved the composition of the negative electrode interfacial film and suppressed further side reactions of the solvent on the negative electrode surface, which is very useful for improving the electrochemical performance of the battery.

[0025] However, many experiments have shown that the cyclic ene vinegar The addition of ether solvents resulted in a higher cyclic ester content than the addition of other solvents. vinegar The ether solvent is likely to accumulate on the surface of the positive electrode, and the cyclic ether solvent that accumulates on the surface of the positive electrode vinegar It was found that the oxidative decomposition of the ether accelerates the outflow of the solvent components in the electrolyte, generating a large amount of gas, ultimately deteriorating the cycle performance and storage performance of the battery. vinegar The viscosity of ether-based solvents is much higher than that of other commonly used solvents, which increases the viscosity of the electrolyte, which is unfavorable for the transport of lithium ions and also unfavorable for the electrochemical performance of the battery.

[0026] In addition, the inventors' research has revealed that vinegar It has been found that lithium ion batteries containing ether-based solvents show a significant deterioration in storage performance and cycle performance at high temperatures compared to normal temperatures. vinegar The ether solvent enriches on the positive electrode surface faster and in larger amounts, and at higher temperatures, the enriched cyclic esters on the positive electrode surface vinegar Since the decomposition of ethylene also accelerates, we speculate that the high temperature environment is the cause of the deterioration of the battery's cycle performance and storage performance.

[0027] The inventors have studied this issue and conducted many experiments. vinegar By adjusting the relative content of ether and lithium salt within a specific range, the high conductivity of the electrolyte can be sufficiently ensured, and such a cyclic ether can be obtained. vinegar This effectively suppresses the rate and amount of enrichment of the ether solvent at the positive electrode, reduces oxidative decomposition at the positive electrode, and also reduces the viscosity of the electrolyte. vinegarWe have found that the cycle performance, storage performance, and power performance of lithium-ion batteries using terephthalate solvents can be improved at high temperatures.

[0028] The electrolyte recipe of the present application is particularly suitable for ternary lithium ion batteries with high nickel atomic content, and even for ternary lithium ion batteries with ultra-high nickel atomic content.

[0029] The electrolyte recipe of the present application is particularly suitable for improving the cycle performance, storage performance, and power performance of lithium-ion batteries at high temperatures.

[0030] [Electrolyte] A first aspect of the present application provides an electrolyte solution, the electrolyte solution comprising an electrolyte salt including a lithium salt and a cyclic ene vinegar a mass fraction of the lithium salt relative to the electrolyte solution is W1; vinegar When the mass fraction of the terbium is W2, the relationship 0.2≦W1 / W2≦1.06 is satisfied.

[0031] The lithium salt of the present application is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorobisoxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0032] The present application vinegar The terephthalate is selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinyl ethylene carbonate (VEC), and optionally, from at least one of ethylene carbonate and propylene carbonate.

[0033] In addition, when the electrolyte solution contains one or more lithium salts, the "mass fraction of the lithium salt relative to the electrolyte solution" means the mass fraction of the total mass of all lithium salts relative to the electrolyte solution. vinegar When the electrolyte contains ether, the cyclic ether vinegar The "mass fraction of ether" refers to the total mass fraction of all cyclic ethers relative to the electrolyte. vinegar The mass fraction of the total mass of the ter.

[0034] The present application aims to develop an electrolyte recipe that has good electrical conductivity, oxidation resistance, electrolyte stability, and appropriate viscosity, while improving the electrical conductivity of the interfacial film of the negative electrode. vinegar When the content of ether and the content of lithium salt satisfy a certain relationship (0.2≦W1 / W2≦1.06), the electrolyte has unexpected beneficial effects, such as good electrical conductivity, oxidation resistance, electrolyte stability, and appropriate viscosity, as well as improving the electrical conductivity of the negative electrode interfacial film and forming a cyclic electrolyte. vinegar It was found that this method suppresses the rate and amount of enrichment of the tertiary solvent at the positive electrode and reduces oxidative decomposition at the positive electrode, thereby providing lithium-ion batteries with good high-temperature cycle performance and high-temperature storage performance.

[0035] Through extensive research by the inventors, it has been found that commercially available general-purpose electrolytes typically contain lithium salts and cyclic enes to provide excellent conductivity for lithium-ion battery electrolytes. vinegar However, it was found that the ratio W1 / W2 between the cyclic ether and the lithium salt was 1.5 or more. vinegar It was found that the ratio of lithium salt to cyclic ether in the electrolyte of lithium-ion batteries was too high, which caused serious oxidative decomposition at the positive electrode, increased gas generation during high-temperature storage, and deteriorated high-temperature cycle performance. vinegarHowever, it was not possible to reduce the W1 / W2 ratio, which is the ratio of the ether solvent, below 1.5. Through extensive experimentation, the present inventors developed an electrolyte that satisfies the condition 0.2≦W1 / W2≦1.06, which improved the high-temperature storage performance and high-temperature cycling performance of the battery. For details, see Table 1.

[0036] In some embodiments, optionally, in the electrolyte solution of the present application, the range of W1 / W2 is 0.5 to 1.06, and optionally 0.8 to 1.0. See Table 1 for details.

[0037] By further narrowing the W1 / W2 range, the electrolyte composition can be optimized to create a good solvent, which allows the electrolyte to form a highly conductive inorganic-organic composite interfacial film on the surfaces of the positive and negative electrodes, thereby significantly improving the high-temperature storage performance and high-temperature cycling performance of the battery, as well as enhancing power performance.

[0038] Optionally, the range of W1 / W2 is a numerical range defined by any of the values ​​set forth in Table 1.

[0039] In some embodiments, the electrolyte solution of the present application optionally comprises a ratio of the cyclic ene to the mass of the organic solvent. vinegar The mass fraction B of the mass of the ter is between 5% and 18%, and optionally between 13% and 16%.

[0040] Research has led to the development of commercially available circular vinegar In an electrolyte containing an ether solvent, the ratio of cyclic ether to the mass of the organic solvent is vinegar The content of cyclic ether is approximately 20% or more, which causes the battery to generate a lot of gas during high-temperature storage, resulting in poor high-temperature cycle performance. vinegar By limiting the B content to 5% to 18%, the high-temperature storage performance, high-temperature cycle performance, and power performance of the battery were significantly improved. Furthermore, by limiting the B value range to 13% to 16%, the high-temperature cycle performance and high-temperature storage performance of the lithium-ion battery were further improved. See Table 2 for details.

[0041] Optionally, the range of B is a numerical range defined by any of the values ​​set forth in Table 2.

[0042] In some embodiments, optionally in the electrolyte solution of the present application, the lithium salt is selected from at least one of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate.

[0043] In some embodiments, when the molar concentration of the lithium bis(fluorosulfonyl)imide is C1 and the molar concentration of the lithium hexafluorophosphate is C2, the ratio thereof, C1 / C2, is 0.05 to 5, and optionally 1 to 3.5.

[0044] In this application, the content of cyclic carbonate is limited, which limits the dissociation of the lithium salt and affects the conductivity of the electrolyte. Through extensive experiments, the inventors have found that using lithium bis(fluorosulfonyl)imide (LiFSI) instead of LiPF6 can improve the conductivity of the electrolyte, but using LiFSI alone accelerates corrosion of the aluminum foil. However, the inventors have found that by using a mixture of LiPF6 and LiFSI and further limiting the ratio C1 / C2, which is the molar concentration C1 of the lithium bis(fluorosulfonyl)imide to the molar concentration C2 of the lithium hexafluorophosphate, within an appropriate range, the cyclic carbonate can be improved. vinegar It was found that this can compensate for the decrease in electrolyte conductivity caused by the reduction in the amount of terpene used, prevent corrosion of the lithium salt against the aluminum foil, and further improve the high-temperature cycle performance and high-temperature storage performance of the battery. For details, see Table 3.

[0045] Optionally, the range of C1 / C2 is a numerical range defined by any of the values ​​set forth in Table 3.

[0046] In some embodiments, optionally, the sum of the molar concentrations of the lithium bis(fluorosulfonyl)imide and the lithium hexafluorophosphate is 0.86 to 1.4M, and optionally 1 to 1.4M.

[0047] Furthermore, the total concentration of LiFSI and LiPF6 must be limited within an appropriate range. If the lithium salt concentration is too high, the electrolyte will be too viscous, resulting in poor high-temperature cycle and high-temperature storage performance, as well as a decrease in battery power performance. Conversely, if the total concentration is too low, the amount of effective lithium ion movement will be too small, resulting in poor high-temperature cycle and high-temperature storage performance. See Table 4 for details.

[0048] Optionally, the range of the sum of the molar concentrations of lithium bis(fluorosulfonyl)imide and the lithium hexafluorophosphate is a numerical range defined by any value listed in Table 4.

[0049] In some embodiments, optionally, the electrolyte solution of the present application includes a film-forming additive, wherein the mass fraction of the film-forming additive relative to the electrolyte solution is A, and the mass fraction of the cyclic ene relative to the electrolyte solution is A. vinegar When the mass fraction of the ether is W2, the relationship 10≦W2 / 5+2×A≦16 is satisfied. The film-forming additive is selected from at least one of fluoroethylene carbonate (FEC), vinylene carbonate (VC), ethylene sulfate (DTD), and 1,3-propane sultone (PS).

[0050] Circular Railway vinegar The ether solvent is involved in the formation of the positive and negative electrodes in the formation process of lithium-ion batteries, but the cyclic ether solvent is vinegar When a film is formed using only a ter, the quality of the formed film may be insufficient, making it difficult to maintain good cycle performance of the battery. However, by using it in combination with a film-forming additive, the quality of the formed film can be improved.

[0051] Through many experiments, it has been found that the mass fraction A of the film-forming additive to the electrolyte solution of the present application and the cyclic ene to the electrolyte solution vinegar When the mass fraction W2 of the ether satisfies the above formula of the present application, the prepared electrolyte can ensure high-quality film formation of the positive and negative electrodes, and the cyclic ether used together can vinegar This allows the electrolyte to achieve its maximum effect (improving the overall conductivity of the electrolyte). Lithium-ion batteries using this material have good high-temperature cycle performance, high-temperature storage performance, and even better power performance. See Table 5 for details.

[0052] Optionally, the range of W2 / 5+2×A is a numerical range defined by any value listed in Table 5, and is optionally 11.9 to 13.5.

[0053] The lithium ion battery of the present application further includes a positive electrode plate, a separator, and a negative electrode plate.

[0054] [Positive electrode] 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 including a positive electrode active material.

[0055] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction of the positive electrode current collector, and the positive electrode film layer is laminated on either one or both of the two facing surfaces of the positive electrode current collector.

[0056] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, the metal foil can be aluminum foil. The composite current collector can include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector can be produced 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)).

[0057] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. For example, the positive electrode active material may include at least one of a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a modified compound of each. Note that the present application is not limited to these materials, and other conventional materials usable 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 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 (simply NCM 333 (sometimes referred to as "LiNi") 0.5 Co 0.2 Mn 0.3 O2 (simply NCM 523 (sometimes referred to as "LiNi") 0.5 Co 0.25 Mn 0.25 O2 (simply NCM 211 (sometimes referred to as "LiNi") 0.6 Co 0.2 Mn 0.2 O2 (simply NCM 622 (sometimes referred to as "LiNi") 0.8 Co 0.1 Mn 0.1 O2 (simply NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05O2) and modified compounds thereof. Examples of the lithium-containing phosphate having an olivine structure include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (sometimes simply referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0058] In some embodiments, the positive electrode membrane layer may further include an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropene copolymer, and a fluorine-containing acrylic resin.

[0059] In some embodiments, the positive electrode film layer may optionally further include a conductive agent, for example, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0060] In some embodiments, a positive electrode plate is manufactured as follows: 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 obtain a positive electrode slurry, which is then applied to a positive electrode current collector and subjected to steps such as drying and cold pressing to obtain a positive electrode plate.

[0061] [Negative electrode] 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 and including a negative electrode active material.

[0062] 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 laminated on either one or both of the two facing surfaces of the negative electrode current collector.

[0063] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, the metal foil can be a copper foil. The composite current collector can include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector can be manufactured 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)).

[0064] In some embodiments, the negative electrode active material may be a battery 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, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0065] In some embodiments, the negative electrode membrane layer may further include 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).

[0066] In some embodiments, the negative electrode film layer may optionally further include 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.

[0067] In some embodiments, the negative electrode membrane layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0068] In some embodiments, a negative electrode plate is manufactured as follows: 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 obtain a negative electrode slurry, which is then applied to a negative electrode current collector and subjected to steps such as drying and cold pressing to obtain a negative electrode plate.

[0069] [Separator] In some embodiments, the lithium ion battery further includes a separator. In this application, the type of separator is not limited, and a separator having a porous structure with good chemical stability and mechanical stability known in the art may be selected.

[0070] In some embodiments, the separator may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. This is not a limitation. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. This is not a limitation.

[0071] In some embodiments, the positive electrode plate, the negative electrode plate and the separator are fabricated into an electrode unit by a winding process or a stacking process.

[0072] [Lithium-ion battery] The present application further provides a lithium-ion battery comprising the electrolyte of the first aspect of the present application.

[0073] In some embodiments, the lithium-ion battery of the present application includes a positive plate and the electrolyte of the first aspect of the present application. x Co y Mn z O2, in which the positive electrode material is expressed as x+y+z=1. vinegar When the mass fraction of nickel is W2 and the content of nickel atoms is x, the relationship 0.5≦W2 / (100x)≦0.72 is satisfied.

[0074] The lithium ion battery fabricated with the electrolyte of the present application and the Ni-Co-Mn layered ternary positive electrode active material exhibits significantly enhanced electrochemical performance and exhibits a cyclic ene property to the electrolyte. vinegar The amount of ether used and the nickel atom content x in the ternary positive electrode active material have a corresponding relationship. Generally, the higher the nickel atom content in the ternary positive electrode active material, the stronger the activity of the ternary positive electrode active material. However, during the use of the battery, the higher the nickel atom content, the faster the oxygen release on the surface of the positive electrode due to the ternary positive electrode active material, and the more cyclic ethylene oxide is formed. vinegarThrough numerous experiments, the inventors of the present application have found that if the relationship between the amount of the electrolyte used and the nickel atom content x of the present application satisfies 0.5≦W2 / (100x)≦0.72, the oxygen release problem of high-nickel batteries can be improved and the cyclic esters on the surface of the positive electrode can be formed. vinegar It was found that the oxidative decomposition of ethers can be effectively reduced, and the ternary lithium-ion batteries fabricated using them have good cycle and power performances. See Table 6 for details.

[0075] In some embodiments, optionally, the nickel atomic content x is 0.5 or greater, and optionally, the nickel atomic content x may be 0.5, 0.65, 0.8, or 0.96. See Table 8 for details.

[0076] The electrolyte recipe of the present application is particularly suitable for ternary lithium ion batteries with high nickel atomic content, and even for ternary lithium ion batteries with ultra-high nickel atomic content, thereby providing good high-temperature storage performance, high-temperature cycle performance, and power performance.

[0077] In some embodiments, in the lithium-ion batteries of the present application, 1540.25 mm of negative electrode material 2 The amount of the cyclic ene supported on the surface of the current collector (unit: g) is H, and the ratio of the amount of the cyclic ene supported on the surface of the current collector to the amount of the electrolyte is H. vinegar When the mass fraction of the terephthalate is W2, the mass fraction satisfies 20≦W2 / H≦166, and optionally 50≦W2 / H≦141.

[0078] Through many experiments, the inventors of the present application have found that the cyclic electrolyte vinegar We found that a synergistic effect can be achieved by selecting the amount of terpene used and the amount of anode material supported, H. When the relationship between the two satisfies 20≦W2 / H≦166, the electrochemical performance of the entire lithium-ion battery can be significantly improved. See Table 7 for details.

[0079] In some embodiments, the lithium ion battery of the present application is a battery having a housing.

[0080] In some embodiments, the lithium-ion battery may include an outer casing, which is used to seal the electrode unit and electrolyte.

[0081] In some embodiments, the lithium ion battery may be packaged in a hard case, such as a hard plastic case, an aluminum case, or a steel case. The lithium ion battery may be packaged in a soft pack, such as a soft pack bag. The soft pack may be made of a plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0082] The present application does not particularly limit the shape of the lithium ion battery, and it may be cylindrical, rectangular, or any other shape. For example, Figure 1 shows an example of a lithium ion battery 5 with a rectangular structure.

[0083] In some embodiments, as shown in FIG. 2 , the exterior includes a housing 51 and a cover plate 53. Here, the housing 51 includes a bottom plate and a side plate connected to the bottom plate, and the bottom plate and side plate are configured to enclose a storage chamber. The housing 51 has an opening communicating with the storage chamber, and the cover plate 53 covers the opening to seal the storage chamber. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode unit 52 by a winding process or a stacking process. The electrode unit 52 is sealed in the storage chamber. An electrolyte is impregnated into the electrode unit 52. The number of electrode units 52 included in the lithium-ion battery 5 can be one or more, and can be selected according to actual needs by those skilled in the art.

[0084] Figure 3 shows an example electrical installation, which may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0085] Example The following examples of the present application are described. It should be understood that the following examples are merely illustrative and serve to explain the present application, and are not intended to limit the present application. In the examples, specific conditions are not specified, and can be based on techniques, conditions, or product descriptions described in literature in the field. For reagents or equipment used without specifying the manufacturer, commercially available conventional products commonly used in the field can be used. The content of each component in the examples of the present application is calculated by mass, excluding water of crystallization, unless otherwise specified.

[0086] Regarding the terms used below, "electrolyte of Example 1-1" means the electrolyte used in the manufacturing process of the lithium-ion battery of Example 1-1, "positive electrode plate of Example 1-1" means the positive electrode plate used in the manufacturing process of the lithium-ion battery of Example 1-1, "negative electrode plate of Example 1-1" means the positive electrode plate used in the manufacturing process of the lithium-ion battery of Example 1-1, "separator of Example 1-1" means the separator used in the manufacturing process of the lithium-ion battery of Example 1-1, and "lithium-ion battery of Example 1-1" means a lithium-ion battery manufactured using the positive electrode, separator, negative electrode, and electrolyte of Example 1-1.

[0087] The raw materials used in the examples of this application are as follows:

[0088] Nickel-cobalt-manganese ternary material (LiMO2, where M is a solid solution of Ni-Co-Mn; see each example for their ratios) Artificial graphite (Guangdong Kaijin New Energy Technology Co., Ltd.) N-methylpyrrolidone (NMP, CAS:872-50-4, Shanghai Macklin Biotechnology Co., Ltd.) Polyvinylidene fluoride (CAS:24937-79-9, Shanghai Macklin Biological Technology Co., Ltd.) Acetylene black (Guangdong Kaijin New Energy Technology Co., Ltd.) Carbon black, a conductive agent (Guangdong Kaijin New Energy Technology Co., Ltd.) Acrylate (CAS:25067-02-1, Shanghai Macklin Biological Technology Co., Ltd.) Ethylene carbonate (EC, CAS:96-49-1, Shanghai Macklin Biological Technology Co., Ltd.) Dimethyl carbonate (DMC, CAS:616-38-6, Shanghai Macklin Biotechnology Co., Ltd.) Ethyl methyl carbonate (EMC, CAS:623-53-0, Shanghai Macklin Biotechnology Co., Ltd.) Lithium hexafluorophosphate (LiPF6, CAS: 21324-40-3, Guangzhou Tianci High-Tech Materials Co., Ltd.) Lithium bisfluorosulfonimide (LiFSI, CAS: 171611-11-3, Guangzhou Tianci High-Tech Materials Co., Ltd.) Fluoroethylene carbonate (FEC, CAS: 114435-02-8, Guangzhou Tianci High-Tech Materials Co., Ltd.)

[0089] Example 1-1 [Preparation of electrolyte] In a glove box with an argon gas atmosphere having a water content of less than 10 ppm, 32.64 g of EC, 60.84 g of EMC, 6.25 g of LiPF6, and 0.15 g of LiFSI were added to a beaker and thoroughly stirred to dissolve, thereby obtaining the electrolyte solution of this example.

[0090] [Production of positive electrode plates] Nickel-cobalt-manganese ternary material (LiNi 0.8 Co 0.1 Mn 0.1 O2), polyvinylidene fluoride as an adhesive, and acetylene black as a conductive agent were mixed in a mass ratio of 8:1:1, and NMP as a solvent was added. The mixture was stirred with a vacuum mixer to obtain a positive electrode slurry. This positive electrode slurry was mixed at a ratio of 0.28 g (dry matter) / 1540.25 mm 2 The aluminum foil was dried at room temperature, then transferred to an oven at 120°C and dried for 1 hour. After that, the foil was cold pressed and cut to obtain a positive electrode plate.

[0091] [Negative electrode plate manufacturing] Artificial graphite, carbon black as a conductive agent, and acrylate as an adhesive were mixed in a mass ratio of 92:2:6, deionized water was added, and the mixture was stirred with a vacuum mixer to obtain a negative electrode slurry. This negative electrode slurry was mixed at a ratio of 0.18 g (dry matter) / 1540.25 mm 2 The amount of the paste was evenly applied to an 8 μm thick negative electrode current collector copper foil, and the copper foil was dried at room temperature, then transferred to a 120°C oven and dried for 1 hour, followed by cold pressing and cutting to obtain a negative electrode plate.

[0092] [Separator] The separator is cellgard 2400 (standard) purchased from Cellgard (company).

[0093] [Lithium-ion battery manufacturing] The positive electrode plate, separator, and negative electrode plate were stacked in this order, with the separator interposed between them to provide isolation, and then wound to form an electric core. The electric core, with a capacity of 4.3 Ah, was then placed in an outer foil package, and 8.6 g of the prepared electrolyte was injected into the dried battery. The resulting battery was then vacuum packaged, left to stand, formed, and molded to obtain a lithium-ion battery.

[0094] Example 1-2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 18.17 g of EC, 72.68 g of EMC, 9 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0095] Examples 1-3 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 10.10 g of EC, 81.74 g of EMC, 8 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0096] Examples 1-4 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 12.83 g of EC, 75.648 g of EMC, 11.38 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the components, thereby obtaining the electrolyte solution of this example.

[0097] Examples 1-5 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 12.67 g of EC, 74.68 g of EMC, 12.5 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0098] Examples 1-6 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 9.86 g of EC, 79.74 g of EMC, 10.25 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0099] Comparative Example 1 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 82.98 g of EC, 4.37 g of EMC, 12.5 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0100] Comparative Example 2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 10.44 g of EC, 78.03 g of EMC, 11.38 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the components, thereby obtaining the electrolyte solution of this example.

[0101] Example 2-1 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 2.93 g of PC, 94.67 g of EMC, 2.25 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0102] Example 2-2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 4.80 g of PC, 91.29 g of EMC, 3.75 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0103] Example 2-3 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 7.51 g of PC, 86.34 g of EMC, 6 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0104] Examples 2-4 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 9.25 g of PC, 83.22 g of EMC, 7.38 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0105] Examples 2-5 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 11.76 g of PC, 78.71 g of EMC, 9.38 g of LiPF6, and 0.15 g of LiFSI to a beaker and dissolving them by stirring thoroughly to obtain the electrolyte solution of this example.

[0106] Examples 2-6 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 13.38 g of PC, 75.84 g of EMC, 10.63 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0107] Examples 2-7 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 15.72 g of PC, 71.62 g of EMC, 12.5 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0108] Examples 2-8 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 17.22 g of PC, 68.88 g of EMC, 13.75 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0109] Example 3-1 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 13.92 g of EC, 73.55 g of EMC, 12.38 g of LiPF6, and 0.15 g of LiFSI to a beaker and stirring thoroughly to dissolve the components, thereby obtaining the electrolyte solution of this example.

[0110] Example 3-2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 14.04 g of EC, 73.32 g of EMC, 11.90 g of LiPF6, and 0.73 g of LiFSI to a beaker and stirring thoroughly to dissolve the components, thereby obtaining the electrolyte solution of this example.

[0111] Example 3-3 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 15.5 g of EC, 70.55 g of EMC, 6.25 g of LiPF6, and 7.7 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0112] Examples 3-4 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 15.82 g of EC, 69.94 g of EMC, 5 g of LiPF6, and 9.24 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0113] Examples 3-5 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 16.04 g of EC, 69.53 g of EMC, 4.17 g of LiPF6, and 10.27 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0114] Examples 3-6 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 16.39 g of EC, 68.85 g of EMC, 2.78 g of LiPF6, and 11.98 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0115] Examples 3-7 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 16.57 g of EC, 68.51 g of EMC, 2.08 g of LiPF6, and 12.83 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0116] Examples 3-8 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 16.62 g of EC, 68.43 g of EMC, 1.92 g of LiPF6, and 13.03 g of LiFSI to a beaker and stirring thoroughly to dissolve the components, thereby obtaining the electrolyte solution of this example.

[0117] Example 4-1 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 10.85 g of EC, 79.39 g of EMC, 4.38 g of LiPF6, and 5.39 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0118] Example 4-2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 13.18 g of EC, 74.97 g of EMC, 5.31 g of LiPF6, and 6.55 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0119] Example 4-3 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 15.5 g of EC, 70.55 g of EMC, 6.25 g of LiPF6, and 7.70 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0120] Example 4-4 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 21.7 g of EC, 58.77 g of EMC, 8.75 g of LiPF6, and 10.78 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0121] Examples 4-5 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 22.48 g of EC, 57.3 g of EMC, 9.06 g of LiPF6, and 11.17 g of LiFSI to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0122] Example 5-1 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 12.30 g of EC, 72.55 g of EMC, 11.44 g of LiPF6, 0.15 g of LiFSI, and 3.55 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0123] Example 5-2 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 10.35 g of EC, 75.87 g of EMC, 9.63 g of LiPF6, 0.15 g of LiFSI, and 4 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0124] Example 5-3 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 12.51 g of EC, 70.89 g of EMC, 11.75 g of LiPF6, 0.15 g of LiFSI, and 4.7 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0125] Example 5-4 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 10.76 g of EC, 73.31 g of EMC, 10.13 g of LiPF6, 0.15 g of LiFSI, and 5.65 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0126] Example 5-5 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 11.03 g of EC, 71.29 g of EMC, 10.63 g of LiPF6, 0.15 g of LiFSI, and 6.9 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0127] Examples 5-6 The manufacturing process of the lithium-ion battery can be generally referred to in Example 1-1, except that the electrolyte solution is prepared in an argon gas glove box with a water content of less than 10 ppm by adding 13.55 g of EC, 66.17 g of EMC, 13.13 g of LiPF6, 0.15 g of LiFSI, and 7 g of FEC to a beaker and stirring thoroughly to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0128] Example 6-1 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.99 Co 0.005 Mn 0.005 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 46.286 g of EC, 39.43 g of EMC, 4.13 g of LiPF, and 10.16 g of LiFSI to a beaker and thoroughly stirring to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0129] Example 6-2 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.69 Co 0.16 Mn 0.15 It is O2.

[0130] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm. 34.28 g of EC, 51.43 g of EMC, 4.13 g of LiPF6, and 10.16 g of LiFSI are added to a beaker, and the mixture is thoroughly stirred to dissolve, thereby obtaining the electrolyte solution of this example.

[0131] Example 6-3 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.47 Co 0.15Mn 0.38 It is O2.

[0132] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 27.86 g of EC, 57.85 g of EMC, 4.13 g of LiPF6, and 10.16 g of LiFSI to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0133] Example 6-4 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.32 Co 0.19 Mn 0.57 It is O2.

[0134] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm. 23.14 g of EC, 62.57 g of EMC, 4.13 g of LiPF6, and 10.16 g of LiFSI are added to a beaker, and the mixture is thoroughly stirred to dissolve, thereby obtaining the electrolyte solution of this example.

[0135] Examples 6-5 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.25 Co 0.18 Mn 0.57 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 20.06 g of EC, 65.65 g of EMC, 4.13 g of LiPF, and 10.16 g of LiFSI to a beaker and thoroughly stirring to dissolve the mixture, thereby obtaining the electrolyte solution of this example.

[0136] Example 7-1 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 1.698 mg / 1540.25 mm 2The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 30.57 g of EC, 63.31 g of EMC, and 6.11 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0137] Example 7-2 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.873 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 17.47 g of EC, 73.80 g of EMC, and 8.73 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0138] Example 7-3 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.192 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 9.61 g of EC, 82.71 g of EMC, and 7.69 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0139] Example 7-4 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.158 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 12.67 g of EC, 75.94 g of EMC, and 11.4 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0140] Example 7-5 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.115 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 12.67 g of EC, 74.67 g of EMC, and 12.67 g of LiPF to a beaker, stirring thoroughly to dissolve the mixture, and then obtaining the electrolyte solution of this example.

[0141] Examples 7-6 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.09 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 12.67 g of EC, 74.67 g of EMC, and 12.67 g of LiPF to a beaker, stirring thoroughly to dissolve the mixture, and then obtaining the electrolyte solution of this example.

[0142] Example 7-7 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.079 mg / 1540.25 mm 2 The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 12.67 g of EC, 74.67 g of EMC, and 12.67 g of LiPF to a beaker, stirring thoroughly to dissolve the mixture, and then obtaining the electrolyte solution of this example.

[0143] Examples 7-8 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the coating amount of the negative electrode slurry in this example is 0.058 mg / 1540.25 mm 2The electrolyte solution was prepared in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 9.61 g of EC, 80.3 g of EMC, and 10.09 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0144] Example 8-1 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.5 Co 0.2 Mn 0.3 It is O2.

[0145] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 16 g of EC, 69.6 g of EMC, and 14.4 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0146] Example 8-2 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.65 Co 0.05 Mn 0.3 It is O2.

[0147] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 16 g of EC, 69.6 g of EMC, and 14.4 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0148] Example 8-3 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.85 Co 0.05 Mn 0.1 It is O2.

[0149] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 16 g of EC, 69.6 g of EMC, and 14.4 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0150] Example 8-4 The manufacturing process of the lithium ion battery can be generally referred to Example 1-1. The difference is that the ternary material used as the positive electrode active material in this example is LiNi 0.96 Co 0.02 Mn 0.02 O2.

[0151] The electrolyte solution preparation step is carried out in a glove box with an argon gas atmosphere having a water content of less than 10 ppm by adding 16 g of EC, 69.6 g of EMC, and 14.4 g of LiPF to a beaker, stirring thoroughly to dissolve, and then obtaining the electrolyte solution of this example.

[0152] [Measurement of parameters and battery performance] 1. Measurement of initial discharge DCR (Direct Current Resistance) At 25°C, each of the lithium-ion batteries of the above examples and comparative examples was charged to 4.25V at a charge rate of 1C, then constant-voltage charged until the current became less than 0.05C, and then discharged at a discharge rate of 1C for 30 minutes. At this time, the SOC of the battery was 50% and the voltage was V1. The battery was then discharged for 30 seconds at a discharge rate of 4C (the current corresponding to 4C was I). The voltage at this time was V2. The initial discharge DCR of the lithium-ion battery = (V1 - V2) / I. See Tables 1 to 8 for specific values.

[0153] 2. Measurement of cycle performance at 60℃ At 60°C, the battery is charged to 4.25V at a constant current of 1C, then charged at a constant voltage of 4.25V until the current becomes 0.05C, and left to stand for 5 minutes. Then, it is discharged to 2.5V at a constant current of 1C, and the obtained capacity is the initial capacity C0. The above steps are repeated for the same battery as above, and counted. The discharge capacity of the battery after 300 cycles is C 300 The cycle capacity retention rate of the battery after 300 cycles is P = C 300 / C0×100%.

[0154] The lithium ion batteries of the examples and comparative examples were measured using the above process. See Tables 1 to 8 for specific values.

[0155] 3. Measurement of storage performance at 60℃ At 25°C, the battery is charged to 4.25V at a constant current of 0.5C, then charged at a constant voltage of 4.25V until the current reaches 0.05C, allowed to stand for 5 minutes, and then discharged to 2.5V at a constant current of 0.5C. The discharge capacity at this point is defined as the initial capacity C0.

[0156] The battery was then charged to 4.25V at a constant current of 0.5C, then charged at a constant voltage of 4.25V until the current reached 0.05C. The battery was then placed in an incubator at 60°C for 60 days before being removed. The removed battery was then left in an ambient atmosphere at 25°C. After the temperature of the lithium-ion battery had cooled to 25°C, the battery was discharged to 2.5V at a constant current of 0.5C, then charged to 4.25V at a constant current of 0.5C, and finally discharged to 2.5V at a constant current of 0.5V. The discharge capacity at this point was designated C1. The high-temperature storage capacity retention of the battery after 60 days of storage was calculated as M = C1 / C0 × 100%.

[0157] The other examples and comparative examples were measured in the same manner as above. See Tables 1 to 8 for specific values.

[0158] [Table 1]

[0159] [Table 2]

[0160] [Table 3]

[0161] [Table 4]

[0162] [Table 5]

[0163] [Table 6]

[0164] [Table 7]

[0165] [Table 8]

[0166] As can be seen from Table 1, the high-temperature cycle capacity retention rate and high-temperature storage capacity retention rate of the lithium ion batteries of all the above Examples are far higher than those of Comparative Example 1-2, and the initial discharge DCR of all the Examples is lower than that of Comparative Example 1-2.

[0167] As can be seen from Examples 1-1 to 1-6, when 0.2≦W1 / W2≦1.06, the high-temperature cycle capacity retention of the lithium-ion batteries was higher than 75% and the high-temperature storage capacity retention was higher than 80%. The initial discharge DCR was also kept within 20.5 mΩ. Furthermore, when 0.8≦W1 / W2≦1.0, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion batteries were further improved.

[0168] As can be seen from Examples 2-1 to 2-8, when the W1 / W2 value is constant, and the B value is within the range of 5% to 18%, the high-temperature cycle capacity retention of the lithium-ion battery is higher than 75% and the high-temperature storage capacity retention is higher than 80%. Furthermore, the initial discharge DCR is kept below 17.2 mΩ. Furthermore, when the B value is within the range of 13% to 16%, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion battery are further improved.

[0169] As can be seen from Examples 3-1 to 3-8, when the values ​​of W1 / W2 and C1+C2 are constant, and the value of C1 / C2 is within the range of 0.05 to 5, the high-temperature cycle capacity retention of the lithium-ion battery is higher than 78.5% and the high-temperature storage capacity retention is higher than 81%. Furthermore, the initial discharge DCR is kept below 17 mΩ. Furthermore, when the value of C1 / C2 is within the range of 1 to 3.5, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion battery are further improved.

[0170] As can be seen from Examples 4-1 to 4-5, when the values ​​of W1 / W2 and C1 / C2 are constant, and the value of (C1 + C2) is within the range of 0.86 to 1.4 M, the high-temperature cycle capacity retention of the lithium-ion battery is higher than 81.5% and the high-temperature storage capacity retention is higher than 82.3%. Furthermore, the initial discharge DCR is kept below 17 mΩ. Furthermore, when the value of (C1 + C2) is within the range of 1 to 1.4, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion battery are further improved.

[0171] As can be seen from Examples 5-1 to 5-6, when W1 / W2 is a constant value, and the value of W2 / 5+2×A is within the range of 10 to 16, the high-temperature cycle capacity retention of the lithium-ion battery is higher than 83% and the high-temperature storage capacity retention is higher than 84%. Furthermore, the initial discharge DCR is kept below 16.5 mΩ. Furthermore, when the value of W2 / 5+2×A is within the range of 11.9 to 13.5, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion battery are further improved.

[0172] As can be seen from Examples 6-1 to 6-5, when the value of W2 / (100x) was within the range of 0.5 to 0.72, the high-temperature cycle capacity retention rate of the lithium-ion batteries was all higher than 81.3%, the high-temperature storage capacity retention rate was all higher than 82%, and the initial discharge DCR was all suppressed to less than 17 mΩ.

[0173] As can be seen from Examples 7-1 to 7-8, when W1 / W2 is a constant value, and when W2 / H is within the range of 20 to 166, the high-temperature cycle capacity retention of the lithium-ion battery is higher than 81.5% and the high-temperature storage capacity retention is higher than 81.3%. Furthermore, the initial discharge DCR is kept below 16.9 mΩ. Furthermore, when W2 / H is within the range of 50 to 141, the high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR of the lithium-ion battery are further improved.

[0174] As can be seen from Examples 8-1 to 8-4, the current LiNi x Co y Mn z Lithium-ion batteries fabricated with commonly used O2 ternary positive electrode active materials, i.e., ternary positive electrode active materials with nickel atomic contents of 0.5, 0.65, 0.85, and 0.96, respectively, all have good high-temperature cycle capacity retention, high-temperature storage capacity retention, and initial discharge DCR.

[0175] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely illustrative, and any embodiment having substantially the same configuration as the technical idea of ​​the present application or achieving the same functions and effects is included within the technical scope of the present application. Furthermore, various modifications of the embodiments that a person skilled in the art can conceive of, and other methods 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 gist of the present application. [Explanation of symbols]

[0176] 5...Lithium-ion battery 51...Housing 52...Electrode unit 53...Top cover assembly

Claims

1. An electrolytic solution containing an electrolyte salt and an organic solvent, the electrolyte salt includes a lithium salt, and the organic solvent includes a cyclic ester; where W1 is a mass fraction of the lithium salt relative to the electrolyte solution, and W2 is a mass fraction of the cyclic ester relative to the electrolyte solution, the relationship 0.2≦W1 / W2≦1.06 is satisfied; W1 ranges from 6.4% to 12.65%, and W2 ranges from 9.86% to 32.68%; The electrolyte salt includes at least one of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate. An electrolyte solution characterized by:

2. 2. The electrolyte solution of claim 1, wherein the W1 / W2 ranges from 0.5 to 1.06, and optionally from 0.8 to 1.

0.

3. The electrolyte solution according to claim 1 or 2, characterized in that a mass fraction B of the mass of the cyclic ester relative to the mass of the organic solvent is 5% to 18%, and optionally 13% to 16%.

4. The cyclic ester contains at least one of ethylene carbonate and propylene carbonate. The electrolyte solution according to any one of claims 1 to 3.

5. When the molar concentration of the lithium bis(fluorosulfonyl)imide is C1 and the molar concentration of the lithium hexafluorophosphate is C2, the ratio C1 / C2 is 0.05 to 5, and optionally 1 to 3.5; Optionally, the sum of the molar concentrations of the lithium bis(fluorosulfonyl)imide and the lithium hexafluorophosphate (C1+C2) is 0.86 to 1.4 M.

5. The electrolyte solution according to claim 4.

6. further comprising a film-forming additive; When the mass fraction of the film-forming additive relative to the electrolytic solution is A and the mass fraction of the cyclic ester relative to the electrolytic solution is W2, the mass fraction satisfies 10≦W2 / 5+2×A≦16. The electrolyte solution according to any one of claims 1 to 5.

7. A lithium ion battery comprising a positive electrode plate, a negative electrode plate, and the electrolyte solution according to any one of claims 1 to 6.

8. The positive electrode plate contains LiNi as a positive electrode active material. ｘ Co ｙ Mn ｚ O ２ Including, where W2 is the mass fraction of the cyclic ester relative to the electrolytic solution, and x is the content of nickel atoms, the relationship 0.5≦W2 / (100x)≦0.72 is satisfied; However, x + y + z = 1 is satisfied.

8. The lithium ion battery according to claim 7.

9. 9. The lithium ion battery of claim 8, wherein the content x of nickel atoms is 0.5 or more, and optionally 0.65, 0.8, or 0.

96.

10. Negative electrode material 1540.25 mm ２ 10. The lithium ion battery according to claim 7, wherein H is the amount (unit: g) of the cyclic ester carried on the current collector surface, and W2 is the mass fraction of the cyclic ester relative to the electrolyte solution.

11. An electrical equipment comprising the lithium ion battery according to any one of claims 7 to 10.

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