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

Abstract

The present application relates to an electrolyte solution containing an organic solvent and an electrolyte salt dissolved in the organic solvent. The electrolyte salt includes an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions. Further, the present application relates to a corresponding secondary battery, battery module, battery pack, and power consumption device. The electrolyte solution uses an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions in the electrolyte salt, so as to effectively improve the cycle performance of the secondary battery, improve the cycle life of the secondary battery, and cause no side reactions without introducing extra impurities.

Description

Technical Field

[0001] The present application relates to the field of secondary battery technology, and more particularly to electrolytes, secondary batteries, battery modules, battery packs, and power-consuming devices.

Background Art

[0002] In recent years, as the application range of ion secondary batteries has become increasingly wide, secondary batteries have been widely applied in many fields such as energy storage power systems such as hydraulic, thermal, wind, and solar power generation plants, and electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the leapfrog development of secondary batteries, higher requirements are also being placed on the cycle life of ion secondary batteries.

[0003] With the increasing demand for energy density, according to the demand and design of ternary cathodes, the materials used have progressed from the initial low-nickel materials to the current high-nickel materials, but the overall life of high-nickel materials is inferior. The reason is that, on the one hand, the increase in nickel content leads to more lithium-nickel mixing in and out, reducing the cycle life of the battery. On the other hand, in the solid electrolyte interphase (SEI) film on the electrode surface with conventional lithium salt electrolytes, the content of organic lithium is low. When the content of organic lithium is low, co-insertion of solvent molecules occurs, destroying the electrode material and further reducing the cycle life of the secondary battery.

[0004] The electrolyte is an important component of a secondary battery. The electrolyte determines the composition and structure of the SEI film and has an important influence on the stability of the electrode structure and the cycle life of the secondary battery. Optimal design of the electrolyte is a major means to improve the cycle life of secondary batteries. Therefore, seeking an electrolyte that can further improve the cycle life of secondary batteries is one of the important research directions for those skilled in the art.

Summary of the Invention

[0005] This application has been made in view of the above problems, and an object thereof is to provide an electrolytic solution, a secondary battery, a battery module, a battery pack, and an electric power consumption device, and the secondary battery containing this electrolytic solution can have a high cycle life.

[0006] To achieve the above object, a first aspect of the present application provides an electrolytic solution containing an organic solvent and an electrolyte salt dissolved in the organic solvent, and the electrolyte salt contains an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions.

[0007] In any embodiment, the other alkali metal ions in the alkali metal double salt include sodium ions and potassium ions.

[0008] In any embodiment, the alkali metal double salt contains sodium ions and potassium ions simultaneously.

[0009] In any embodiment, the alkali metal double salt is Li a Na b K c PF 6 、Li a Na b K c BOB、Li a Na b K c ODFB、Li a Na b K c TFOP、Li a Na b K c PO 2 F 2 、Li a Na b K c TFSI、Li a Na b K c FSIとLi a Na b K c including one or more of BODFP, a + b + c = 1, 0.5 ≦ a < 1.

[0010] In any embodiment, the electrolyte salt includes a base lithium salt, and the base lithium salt is LiPF 6 , LiBOB, LiODFB, LiTFOP, LiPO 2 F 2 , LiTFSI, LiFSI, and one or more of LiBODFP.

[0011] In any embodiment, the mass ratio of the base lithium salt to the alkali metal double salt in the electrolyte salt is X:1, 0.65 ≤ X < 1.

[0012] In any embodiment, 0.7 ≤ X < 0.9.

[0013] In any embodiment, the anion types of the base lithium salt and the alkali metal double salt are the same.

[0014] In any embodiment, the molar concentration of the electrolyte salt in the electrolyte solution is 0.5 mol / L to 2 mol / L.

[0015] In any embodiment, the organic solvent includes one or more of dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethylene carbonate, propylene carbonate, and diethyl carbonate.

[0016] The second aspect of the present application provides a secondary battery including the electrolyte solution according to the first aspect of the present application.

[0017] In any embodiment, the positive electrode active material in the positive electrode plate of the secondary battery is a positive electrode active material having a layered structure.

[0018] The third aspect of the present application further provides a battery module including the secondary battery according to the second aspect of the present application.

[0019] The fourth aspect of the present application further provides a battery pack including the battery module according to the third aspect of the present application.

[0020] The fifth aspect of the present application further provides a power consumption device including at least one of the secondary battery according to the second aspect of the present application, the battery module according to the third aspect of the present application, or the battery pack according to the fourth aspect of the present application.

[0021] The electrolytic solution of the present application uses an alkali metal double salt containing an electrolyte salt, lithium ions, and at least one kind of alkali metal ion other than lithium ions. First, the radius of the alkali metal ion (for example, sodium ion, potassium ion) excluding lithium in this alkali metal double salt is larger than that of lithium, and it inserts into a part of the lithium sites of the layered positive electrode during the first discharge, enhances the stability of the layered structure, can prevent the mixing of Li / Ni in the layered positive electrode, and further improves the cycle performance of the secondary battery. Next, sodium ions, potassium ions, etc. in the alkali metal double salt help to increase the component of organic lithium in the SEI during the SEI film formation process of the first charge and discharge, further effectively improve the co-intercalation of solvent molecules, avoid the destruction of the electrode material due to the co-intercalation of solvent molecules, and can greatly improve the cycle performance of the electrode. Then, some lithium sites in the lithium salt are replaced with sodium salts, potassium salts, etc. with a larger ionic radius. Sodium ions and potassium ions can occupy the same spatial position as lithium ions, have the same energy level, and the sodium ion and potassium ion structure occupying the original position lithium sites in the lithium salt is more stable. The lithium holes provide a stable space for sodium storage and potassium storage, reduce the failure rate of insertion and desorption of sodium ions and potassium ions with respect to the corresponding lithium sites, are advantageous for the more continuous action of sodium and potassium ions, and have the same movement trajectory during the desorption of ions during charge and discharge, can quantitatively improve the cycle life of the cell, and do not cause side reactions without introducing extra impurities.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0023] The following is a detailed description of embodiments specifically disclosing the electrolyte, secondary battery, battery module, battery pack, and electric power consuming device of the present application with appropriate reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of well-known matters and duplicate descriptions of structures that are actually the same may be omitted. This is to avoid making the following description unnecessarily redundant and to enable those skilled in the art to easily understand. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and do not limit the subject matter described in the claims.

[0024] The "ranges" disclosed in this application are limited in the form of a lower limit and an upper limit. A given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a specific range. The ranges thus defined may or may not include the end values, and any combination is possible, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, it can also be assumed to be understood as ranges of 60 - 110 and 80 - 120. Also, if 1 and 2 are listed as the minimum range values and 3, 4, and 5 are listed as the maximum range values, all of the ranges of 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5 can be assumed. In this application, unless otherwise specified, the numerical range of "a - b" represents a shortened expression of any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" are listed in this specification, and "0 - 5" is just an abbreviated representation of the combinations of these numbers. Also, when a parameter is expressed as an integer ≧ 2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0025] Unless otherwise specified, all embodiments and alternative embodiments of this application can be combined with each other to form a new technical solution.

[0026] Unless otherwise specified, all technical features and alternative technical features of this application can be combined with each other to form a new technical solution.

[0027] Unless otherwise specified, all steps of this application may be performed in order or randomly, and preferably, they are performed in order. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, the fact that the method mentioned above may further include step (c) means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0028] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application represent an open type and may also be a closed type. For example, the above "comprising" and "including" may further include or contain other components not listed, or may include or contain only the components listed.

[0029] Unless otherwise specified, the term "or" in this application is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the conditions where A is true (or exists) and B is false (or does not exist), where A is false (or does not exist) but B is true (or exists), and where both A and B are true (or exist) satisfy "A or B".

[0030] Currently, due to the leapfrog development of secondary batteries, higher requirements are also demanded for the cycle performance of secondary batteries. Secondary batteries with excellent cycle performance have very high requirements for electrolytes. Therefore, seeking electrolytes that can further improve the cycle performance of secondary batteries is one of the important research directions for those skilled in the art.

[0031] With the increasing demand for the energy density of secondary batteries, ternary cathode materials currently often adopt high-nickel materials, and the overall lifespan of high-nickel materials is generally poor. On the other hand, the increase in nickel content brings about more lithium-nickel mixing, further reducing the cycle life of secondary batteries. On the other hand, the content of organic lithium in the SEI film formed by conventional lithium salt electrolytes is low, and co-intercalation of solvent molecules occurs, easily destroying the electrode material, and further reducing the cycle life of secondary batteries.

[0032] The inventors have developed through research an electrolyte using an alkali metal double salt containing lithium ions and other alkali metal ions (such as sodium, potassium, etc.) other than lithium ions as the electrolyte salt of the electrolyte. This electrolyte can effectively improve the cycle performance of secondary batteries and improve the cycle life of secondary batteries.

[0033] In some embodiments, the first aspect of the present application provides an electrolyte containing an organic solvent and an electrolyte salt dissolved in the organic solvent. Here, the electrolyte salt includes an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions.

[0034] The electrolyte of the present application uses an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions as the electrolyte salt. The radius of other alkali metal ions (such as sodium ions, potassium ions) other than lithium in this alkali metal double salt is larger than that of lithium, and in the first discharge process, it inserts into a part of the lithium sites of the layered cathode, enhancing the stability of the layered structure, preventing the mixing of Li / Ni in the layered cathode, and further improving the cycle performance of secondary batteries.

[0035] On one hand, sodium ions, potassium ions, etc. in the alkali metal double salt are helpful for increasing the content of organolithium in the SEI during the SEI film formation process of the first charge and discharge. Furthermore, they can effectively improve the co-intercalation of solvent molecules, avoid the destruction of the electrode material caused by the co-intercalation of solvent molecules, and greatly improve the cycle performance of the electrode.

[0036] When sodium salts, potassium salts, etc. are directly added to lithium salts to form electrolyte salts, on one hand, in the process of manufacturing the electrolyte solution, in order to introduce sodium salts, potassium salts, etc., an additional introduction through a separate pipeline and an additional purification process are required. This series of processes requires the introduction support of additional equipment and an increase in production costs. On the other hand, when simply adding sodium salts and potassium salts to lithium salts, a large amount of sodium and potassium ions will be released into the electrolyte solution. However, these sodium and potassium ions are not bound by ionic bonds, and the irregular movement of the ions is large. The improvement of the SEI film cannot be quantitatively controlled. Moreover, when simply adding sodium salts and potassium ion salts, extra anions are introduced. In the same solvent, the type of metal salt changes the thermodynamic stability and solvation structure of the electrolyte solution, affects the decomposition behavior of the electrolyte solution, and further changes the interfacial properties between the electrode and the electrolyte solution and the electrochemical performance of the electrode. When the electronegativity is different between different anions, the anions enter the solvation layer and participate in the solvation structure reaction, accelerating the decomposition of the electrolyte solution and causing irreversible losses.

[0037] In this application, some lithium sites in the lithium salt are replaced with alkali metal double salts such as sodium salts and potassium salts with a larger ionic radius. Compared with the method of directly adding sodium salts and potassium salts to the lithium salt, sodium ions and potassium ions in the alkali metal double salt can occupy the same spatial position as lithium ions, have the same energy level, and the sodium ion and potassium ion structures occupying the original position lithium sites in the lithium salt are more stable. Lithium holes provide stable spaces for sodium storage and potassium storage, reduce the failure rate of the detachment and insertion of sodium ions and potassium ions into the corresponding lithium sites, are beneficial to the more sustainable action of sodium and potassium ions, and when ions escape during charge and discharge, they have the same movement trajectory, can quantitatively improve the cycle life of the secondary battery, and do not introduce extra impurities or cause side reactions.

[0038] In some embodiments, other alkali metal ions in the alkali metal double salt include sodium ions and potassium ions. As can be understood, other alkali metal ions can include alkali metal ions such as rubidium ions and cesium ions.

[0039] In some embodiments, the alkali metal double salt contains sodium ions and potassium ions simultaneously. That is, the alkali metal double salt contains two or more other alkali metal ions, and these two or more other alkali metal ions include sodium ions and potassium ions.

[0040] In some embodiments, the alkali metal double salt is Li a Na b K c PF 6 、Li a Na b K c BOB、Li a Na b K c ODFB、Li a Na b K c TFOP、Lia Na b K c PO 2 F 2 、 Li a Na b K c TFSI, Li a Na b K c FSI and Li a Na b K c contains one or more of BODFP, and a + b + c = 1, 0.5 ≤ a < 1. Therefore, the other alkali metal ions in the above alkali metal double salt are sodium and potassium. By using the above alkali metal double salt as the electrolyte salt, the cycle life of the secondary battery can be effectively improved. Here, a, b, and c respectively represent the number of lithium, sodium, and potassium atoms in the above alkali metal double salt molecular formula.

[0041] Note that the above "0.5 ≤ a < 1" includes the minimum value and the maximum value of the range, and each value between the minimum value and the maximum value. Specific examples include the values in the examples and 0.6, 0.7, 0.8, 0.9, but are not limited thereto.

[0042] In any embodiment, the electrolyte salt also contains a base lithium salt, and the base lithium salt is LiPF 6 , LiBOB, LiODFB, LiTFOP, LiPO 2 F 2 , LiTFSI, LiFSI and one or more of LiBODFP. Therefore, the electrolyte salt contains both an alkali metal double salt and a base lithium salt. In other embodiments, it should be understood that the electrolyte salt may contain only the alkali metal double salt and not necessarily the above base lithium salt.

[0043] Furthermore, when the electrolyte salt contains both an alkali metal double salt and a base lithium salt at the same time, the anion in the alkali metal double salt is the same type as the anion in the base lithium salt.

[0044] In any embodiment, the mass ratio of the base lithium salt to the alkali metal double salt in the electrolyte salt is X:1, where 0.65 ≤ X < 1. As can be understood, the mass content of the base lithium salt in the electrolyte salt is less than the mass content of the alkali metal double salt.

[0045] It should be noted that the above "0.65 ≤ X < 1" includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value. Specific examples include the values in the examples and 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.82, 0.85, 0.88, 0.90, 0.92, 0.95, 0.98, but are not limited thereto.

[0046] In any embodiment, 0.7 ≤ X < 0.9.

[0047] In any embodiment, the molar concentration of the electrolyte salt in the electrolyte is 0.5 mol / L to 2 mol / L.

[0048] In any embodiment, the organic solvent includes one or more of dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethylene carbonate, propylene carbonate, and diethyl carbonate. That is, the organic solvent in the electrolyte may include any of the above organic solvents, or may simultaneously include two or more of the above organic solvents.

[0049] The second aspect of the present application provides a secondary battery including the electrolyte described in the first aspect of the present application. Thereby, the secondary battery has good cycle performance and a long cycle life.

[0050] In any embodiment, the positive electrode active material on the positive electrode plate of the secondary battery is a positive electrode active material having a layered structure.

[0051] The third aspect of the present application further provides a battery module including the secondary battery according to the second aspect of the present application.

[0052] A fourth aspect of the present application further provides a battery pack including the battery module according to the third aspect of the present application.

[0053] A fifth aspect of the present application further provides a power consumption device including at least one of the secondary battery according to the second aspect of the present application, the battery module according to the third aspect of the present application, or the battery pack according to the fourth aspect of the present application.

[0054] Hereinafter, the secondary battery, battery module, battery pack, and power consumption device of the present application will be described with appropriate reference to the drawings.

[0055] In one embodiment of the present application, a secondary battery is provided.

[0056] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charge and discharge process of the battery, active ions reciprocate between the positive electrode plate and the negative electrode plate for insertion and desorption. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator is installed between the positive electrode plate and the negative electrode plate, mainly serving to prevent short-circuiting between the positive and negative electrodes and allowing ions to pass through.

[0057] (Positive electrode plate) The positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector, and the positive electrode film layer contains a positive electrode active material.

[0058] As an example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode film layer is provided on one or both of the two facing surfaces of the positive electrode current collector.

[0059] In some embodiments, the positive electrode current collector may employ a metal foil sheet or a composite current collector. For example, as the metal foil sheet, an aluminum foil may be employed. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material on a polymer material substrate. Here, the metal materials include, but are not limited to, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc. The polymer material substrates include, but are not limited to, substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0060] In some embodiments, the positive electrode active material may further include a positive electrode active material for batteries well-known in the art. As an example, the positive electrode active material may include at least one material among olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery 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 are lithium cobalt oxide (e.g., LiCoO 2 ), lithium nickel oxide (e.g., LiNiO 2 ), lithium manganese oxide (e.g., LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (which may be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523 may be abbreviated as), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (NCM 211 may be abbreviated as), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622 may be abbreviated as), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811 may be abbreviated as), lithium nickel cobalt aluminum oxide (for example, LiNi 0.85 Co 0.15 Al 0.05 O 2 ), etc., and may include at least one of modified compounds thereof, but are not limited thereto. Examples of olivine-structured lithium-containing phosphates include lithium iron phosphate (for example, LiFePO 4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (for example, LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon, but are not limited thereto.

[0061] The weight ratio in the positive electrode film layer of the positive electrode active material is 80 to 100% by weight based on the total weight of the positive electrode film layer.

[0062] In some embodiments, the positive electrode film layer may further optionally contain an adhesive. By way of example, the adhesive 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 fluorine - containing acrylate resin. The weight ratio of the adhesive in the positive electrode film layer is 0 to 20% by weight based on the total weight of the positive electrode film layer.

[0063] In some embodiments, the positive electrode film layer may further optionally contain a conductive agent. By way of example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the positive electrode film layer is 0 to 20% by weight based on the total weight of the positive electrode film layer.

[0064] In some embodiments, the positive electrode plate may be manufactured by the following method. The above - mentioned 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 (such as N - methylpyrrolidone) to form a positive electrode slurry, where the solid content of the positive electrode slurry is 40 to 80 wt%, the viscosity at room temperature is adjusted to 5000 to 25000 mPa·s, the positive electrode slurry is coated on the surface of the positive electrode current collector and dried, and then the positive electrode plate is formed through cold pressing by a cold rolling machine. The unit surface density of the positive electrode powder coating is 150 to 350 mg / cm 2 and the consolidation density of the positive electrode plate is 3.0 to 3.6 g / cm 3 and optionally 3.3 to 3.5 g / cm 3 is.

[0065] The calculation formula for the consolidation density is consolidation density = coating surface density / (thickness of the electrode plate after pressing - thickness of the current collector).

[0066] (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, and the negative electrode film layer contains a negative electrode active material.

[0067] As an example, the negative electrode current collector has two surfaces facing each other in its own thickness direction, and the negative electrode film layer is disposed on either one or both of the two opposing surfaces of the negative electrode current collector.

[0068] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, as the metal foil sheet, a copper foil may be employed. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material on the polymer material base. Here, the metal material includes, but is not limited to, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc., and the polymer material base includes, but is not limited to, substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0069] In some embodiments, the negative electrode active material may employ a negative electrode active material for batteries well-known in the art. As an example, the negative electrode active material may include at least one of materials such as 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 silicon alone, silicon oxide, silicon carbon composite, silicon nitride composite, and silicon alloy. The tin-based material may be selected from at least one of tin alone, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery may also be used. These negative electrode active materials may be used alone, or two or more of them may be used in combination.

[0070] In some embodiments, the negative electrode film layer optionally further contains an adhesive. The adhesive 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). The weight ratio of the adhesive in the negative electrode film layer is 0 to 30% by weight based on the total weight of the negative electrode film layer.

[0071] In some embodiments, the negative electrode film layer optionally further contains a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the negative electrode film layer is 0 to 20% by weight based on the total weight of the negative electrode film layer.

[0072] In some embodiments, the negative electrode film layer optionally further contains other auxiliaries, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)). The weight ratio of the other auxiliaries in the negative electrode film layer is 0 to 15% by weight based on the total weight of the negative electrode film layer.

[0073] In some embodiments, the negative electrode plate may be manufactured by the following method. The above components for manufacturing the negative electrode plate, such as the negative electrode active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, where the solid content of the negative electrode slurry is 30 to 70 wt%, and the viscosity at room temperature is adjusted to 2000 to 10000 mPa·s. The obtained negative electrode slurry is coated on a negative electrode current collector and, after a drying process, is cold-pressed, for example, rolled, to obtain a negative electrode plate. The unit surface density of the negative electrode powder coating is 75 to 220 mg / m 2 and the consolidation density of the negative electrode plate is 1.2 to 2.0 g / m 3 is.

[0074] (Electrolyte) The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. For the secondary battery of the present application, the electrolyte of the present application is used. The electrolyte contains an electrolyte salt and an organic solvent. Here, the electrolyte salt includes an alkali metal double salt containing lithium ions and at least one kind of alkali metal ion other than lithium ions.

[0075] In some embodiments, the alkali metal double salt is Li a Na b K c PF 6 、Li a Na b K c BOB, Li a Na b K c ODFB, Li a Na b K c TFOP, Li a Na b K c PO 2 F 2 、Li a Na b K c TFSI, Li a Na b K c FSI and Li a Na b K c including one or more of BODFP, where a + b + c = 1 and 0.5 ≤ a < 1.

[0076] In some embodiments, the electrolyte salt also includes a base lithium salt, and the base lithium salt is LiPF 6 、LiBOB, LiODFB, LiTFOP, LiPO 2 F 2 、LiTFSI, LiFSI and one or more of LiBODFP.

[0077] In some embodiments, the mass ratio of the base lithium salt to the alkali metal double salt in the electrolyte salt is X:1, where 0.65 ≤ X < 1.

[0078] In some embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, and diethyl carbonate.

[0079] In some embodiments, the electrolyte may further optionally include an additive. For example, the additive may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some performances of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, and the like.

[0080] (Separator) In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of the separator, and any known separator having good chemical stability and mechanical stability and having a porous structure may be selected.

[0081] In some embodiments, the material of the separator may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0082] In some embodiments, the thickness of the separator is 6 to 40 μm, and optionally 12 to 20 μm.

[0083] In some embodiments, the positive electrode plate, the negative electrode plate, and the separator may be used to manufacture an electrode assembly by a winding process or a lamination process.

[0084] In some embodiments, the secondary battery may include an exterior body. The exterior body may be used to package the above electrode assembly and electrolyte.

[0085] In some embodiments, the exterior of the secondary battery may be a rigid case, such as a rigid 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 material of the pouch may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0086] This application does not particularly limit the shape of the secondary battery, and it may be cylindrical, square, or any other arbitrary shape. For example, FIG. 1 shows a secondary battery 5 having a square structure as an example.

[0087] In some embodiments, referring to FIG. 2, the exterior may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates surround to form an accommodation cavity. The case 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can close the accommodation cavity by covering the opening. The positive electrode plate, the negative electrode plate, and the separator can form an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the accommodation cavity. The electrolytic solution infiltrates the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select according to actual specific needs.

[0088] In some embodiments, as shown in FIG. 3, the secondary battery 5 may be assembled into a battery module 4, and the number of secondary batteries 5 included in the battery module 4 may be one or more. The specific number can be selected by those skilled in the art based on the application and capacity of the battery module 4.

[0089] In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged according to any other method. Further, the plurality of secondary batteries 5 may be fixed with a fastener.

[0090] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of secondary batteries 5 are accommodated in the accommodation space.

[0091] In some embodiments, as shown in FIGS. 4 and 5, the battery module 4 may further be assembled into the battery pack 1, and the number of battery modules 4 included in the battery pack 1 may be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack 1.

[0092] 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. The upper housing 2 is provided to cover the lower housing 3 and can form a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box according to any method.

[0093] In addition, the present application further provides a power consumption device 6, and the power consumption device 6 includes at least one of the secondary battery 5, the battery module 4, or the battery pack 1 according to the present application. The secondary battery 5, the battery module 4, or the battery pack 1 may be used as a power source of the power consumption device 6, and may also be used as an energy storage unit of the power consumption device 6. The power consumption device 6 may include, but is not limited to, mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, and satellites, energy storage systems, etc.

[0094] As the power consumption device 6, the secondary battery 5, the battery module 4, or the battery pack 1 can be selected according to the requirements in its use.

[0095] FIG. 4 shows a power consumption device 6 as an example. The power consumption device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. In order to meet the demand for high power and high energy density of the secondary battery 5 of the power consumption device 6, the battery pack 1 or the battery module 4 can be used.

[0096] Another example of the device may be a mobile phone, a tablet computer, a notebook computer, or the like. The device is generally required to be lightweight and can use the secondary battery 5 as a power source.

[0097] Examples In order to more clearly illustrate the technical problems, technical solutions, and beneficial effects to be solved by the present application, the present application will be described in more detail below in conjunction with examples and drawings. Obviously, the described examples are only some examples of the present application, not all examples. The description of at least one exemplary example below is for illustrative purposes only and does not limit the present application and its applications. All other examples obtained by those skilled in the art based on the examples of the present application without creative efforts belong to the protection scope of the present application.

[0098] If specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature of the technical field or the product handling instructions. For the reagents or instruments used, those not specified by the manufacturer are all common products that can be purchased commercially.

[0099] Example 1 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 PF 6 is. It is prepared into an electrolyte with a concentration of 1M. Here, the electrolyte salt Li0.5 Na 0.3 K 0.2 PF 6 can be produced by the hydrogen fluoride solvent method, and the reaction process is as follows: (0.5LiF + 0.3NaF + 0.2KF) + PF 5 + CH 3 CN → Li 0.5 Na 0.3 K 0.2 (CH 3 CN) 4 PF 6 → Li 0.5 Na 0.3 K 0.2 PF 6 Manufacture of the positive electrode plate of the secondary battery: 1) Mix polyvinylidene fluoride (PVDF), the layered positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O 2 、and carbon black Super P as the conductive agent in a mass ratio of 90:5:5, adjust the addition amount of the solvent with N-methylpyrrolidone (NMP) as the solvent, and control the slurry viscosity to 100 mPa·s to 20000 mPa·s. Coat this slurry on the positive electrode current collector using a coater or a spray coater. After drying at 85°C, perform cold pressing, and then perform deburring, cutting, and slitting operations. Dry in a vacuum condition at 85°C for 4 h, weld the tabs, and manufacture the positive electrode plate of the secondary battery that meets the requirements.

[0100] Manufacture of the negative electrode plate of the secondary battery: Add graphite as the negative electrode active material, conductive agent Super-P, thickener CMC, and adhesive SBR in a mass ratio of 96.5:1.0:1.0:1.5 to deionized water as the solvent, mix uniformly to manufacture the negative electrode slurry, apply the negative electrode slurry to the current collector copper foil, and dry at 85°C. Then perform deburring, cutting, and slitting operations, and further dry in a vacuum condition at 110°C for 4 h, weld the tabs, and manufacture the negative electrode plate of the secondary battery that meets the requirements.

[0101] Manufacture of secondary battery: Using a 12-μm polypropylene film as a separator, stack the positive electrode plate, separator, and negative electrode plate in order. Place the separator between the positive and negative electrode plates to perform an isolation function, and then wind them to obtain a rectangular bare cell. After packaging the bare cell with aluminum foil and injecting the electrolyte, perform vacuum packaging and repeat multiple charge and discharge cycles to complete the manufacture of the secondary battery.

[0102] Example 2 Manufacture of electrolyte for secondary battery: Using a mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) as an organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 BOB. Prepare an electrolyte with a concentration of 1 M. The electrolyte salt Li 0.5 Na 0.3 K 0.2 BOB can be manufactured by the hydrogen fluoride solvent method.

[0103] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0104] Example 3 Manufacture of electrolyte for secondary battery: Using a mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) as an organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 ODFB. Prepare an electrolyte with a concentration of 1 M. The electrolyte salt Li 0.5 Na 0.3 K 0.2 ODFB can be manufactured by the hydrogen fluoride solvent method.

[0105] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0106] Example 4 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 TFOP. It is prepared into an electrolyte with a concentration of 1 M. The electrolyte salt Li 0.5 Na 0.3 K 0.2 TFOP can be manufactured by the hydrogen fluoride solvent method.

[0107] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0108] Example 5 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 PO 2 F 2 is. It is prepared into an electrolyte with a concentration of 1 M. The electrolyte salt Li 0.5 Na 0.3 K 0.2 PO 2 F 2 can be manufactured by the hydrogen fluoride solvent method.

[0109] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0110] Example 6 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2It is TFSI. It is prepared in an electrolyte solution with a concentration of 1 M. The electrolyte salt is Li 0.5 Na 0.3 K 0.2 TFSI can be produced by the hydrogen fluoride solvent method.

[0111] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0112] Example 7 Production of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is Li 0.5 Na 0.3 K 0.2 FSI. It is prepared in an electrolyte solution with a concentration of 1 M. The electrolyte salt is Li 0.5 Na 0.3 K 0.2 FSI can be produced by the hydrogen fluoride solvent method.

[0113] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0114] Example 8 Production of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is Li 0.5 Na 0.3 K 0.2 BODFP. It is prepared in an electrolyte solution with a concentration of 1 M. The electrolyte salt is Li 0.5 Na 0.3 K 0.2 BODFP can be produced by the hydrogen fluoride solvent method.

[0115] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0116] Example 9 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.7 Na 0.2 K 0.1 PF 6 is. It is prepared into an electrolyte with a concentration of 1 M. Here, the electrolyte salt Li 0.7 Na 0.2 K 0.1 PF 6 can be manufactured by the hydrogen fluoride solvent method.

[0117] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0118] Example 10 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.8 Na 0.1 K 0.1 PF 6 is. It is prepared into an electrolyte with a concentration of 1 M. Here, the electrolyte salt Li 0.8 Na 0.1 K 0.1 PF 6 can be manufactured by the hydrogen fluoride solvent method.

[0119] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0120] Example 11 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.9 Na 0.05 K 0.05 PF 6It is prepared into an electrolyte solution with a concentration of 1 M. Here, the electrolyte salt is Li 0.9 Na 0.05 K 0.05 PF 6 can be produced by the hydrogen fluoride solvent method.

[0121] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0122] Example 12 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent. Here, the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiPF 6 and Li 0.5 Na 0.3 K 0.2 PF 6 is used. The mass ratio of LiPF 6 and Li 0.5 Na 0.3 K 0.2 PF 6 is 0.7:1, and it is prepared into an electrolyte solution with a concentration of 1 M.

[0123] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0124] Example 13 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent. Here, the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiBOB and Li 0.5 Na 0.3 K 0.2 BOB. The mass ratio of LiBOB and Li 0.5 Na 0.3 K 0.2 BOB is 0.8:1, and it is prepared into an electrolyte solution with a concentration of 1 M.

[0125] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0126] Example 14 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiODFB and Li 0.5 Na 0.3 K 0.2 ODFB. The mass ratio of LiODFB and Li 0.5 Na 0.3 K 0.2 ODFB is 0.9:1, and it is prepared into an electrolyte with a concentration of 1 M.

[0127] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0128] Example 15 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 PF 6 is. It is prepared into an electrolyte with a concentration of 1 M.

[0129] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0130] Example 16 Manufacture of the electrolyte of the secondary battery: A mixture of dimethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate is used as the organic solvent, where the mass ratio of each component is dimethyl carbonate:ethyl methyl carbonate:methyl propyl carbonate = 20:30:40. The electrolyte salt in the electrolyte is Li 0.5 K 0.5 BOB. It is prepared into an electrolyte with a concentration of 0.5 M.

[0131] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0132] Example 17 Manufacture of the electrolyte of the secondary battery: A mixture of methyl formate, methyl acetate, and methyl butyrate is used as the organic solvent, where the mass ratio of each component is methyl formate: methyl acetate: methyl butyrate = 30:20:30. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 ODFB. It is prepared into an electrolyte with a concentration of 1.5M.

[0133] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0134] Example 18 Manufacture of the electrolyte of the secondary battery: A mixture of ethyl propionate, ethylene carbonate, and propylene carbonate is used as the organic solvent, where the mass ratio of each component is ethyl propionate: ethylene carbonate: propylene carbonate = 30:20:50. The electrolyte salt in the electrolyte is Li 0.5 K 0.5 TFOP. It is prepared into an electrolyte with a concentration of 2M.

[0135] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0136] Example 19 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 PO 2 F 2 is. It is prepared into an electrolyte with a concentration of 0.8M.

[0137] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0138] Example 20 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 TFSI. It is prepared into an electrolyte with a concentration of 1.2 M.

[0139] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0140] Example 21 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li 0.5 K 0.5 FSI. It is prepared into an electrolyte with a concentration of 1 M.

[0141] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0142] Example 22 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 BODFP. It is prepared into an electrolyte with a concentration of 1.8 M.

[0143] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0144] Example 23 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li0.7 K 0.3 PF 6 It is. Prepare it into an electrolyte solution with a concentration of 0.9 M.

[0145] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0146] Example 24 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is Li 0.8 Na 0.2 PF 6 It is. Prepare it into an electrolyte solution with a concentration of 1 M.

[0147] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0148] Example 25 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is Li 0.9 K 0.1 PF 6 It is. Prepare it into an electrolyte solution with a concentration of 1 M.

[0149] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0150] Example 26 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiPF 6 and Li 0.5 Na 0.5 PF 6 It is. LiPF 6 and Li0.5 Na 0.5 PF 6 The mass ratio of them is 0.7:1. It is prepared into an electrolyte solution with a concentration of 1M.

[0151] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0152] Example 27 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiBOB and Li 0.5 K 0.5 BOB. The mass ratio of LiBOB and Li 0.5 K 0.5 BOB is 0.8:1. It is prepared into an electrolyte solution with a concentration of 1M.

[0153] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0154] Comparative Example 1 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiPF 6 and it is prepared into an electrolyte solution with a concentration of 1M.

[0155] The positive electrode plate, negative electrode plate and secondary battery are manufactured in the same manner as in Example 1.

[0156] Comparative Example 2 Manufacture of the electrolyte solution of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte solution is LiBOB and it is prepared into an electrolyte solution with a concentration of 1M.

[0157] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0158] Comparative Example 3 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiODFB. It is prepared into an electrolyte with a concentration of 1 M.

[0159] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0160] Comparative Example 4 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiTFOP. It is prepared into an electrolyte with a concentration of 1 M.

[0161] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0162] Comparative Example 5 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiPO 2 F 2 is used. It is prepared into an electrolyte with a concentration of 1 M.

[0163] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0164] Comparative Example 6 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiTFSI. It is prepared into an electrolyte with a concentration of 1M.

[0165] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0166] Comparative Example 7 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiFSI. It is prepared into an electrolyte with a concentration of 1M.

[0167] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0168] Comparative Example 8 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiBODFP. It is prepared into an electrolyte with a concentration of 1M.

[0169] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0170] Comparative Example 9 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.4 Na 0.5 K 0.1 PF 6 and it is prepared into an electrolyte with a concentration of 1M.

[0171] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0172] Comparative Example 10 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is all Li 0.3 Na 0.3 K 0.4 PF 6 and is prepared into an electrolyte with a concentration of 1 M.

[0173] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0174] Comparative Example 11 Manufacture of the electrolyte of the secondary battery: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as the organic solvent, where the mass ratio of each component is EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiPF 6 and Li 0.5 Na 0.3 K 0.2 PF 6 There is. The mass ratio of LiPF 6 and Li 0.5 Na 0.3 K 0.2 PF 6 is 0.4:1, and it is prepared into an electrolyte with a concentration of 1 M.

[0175] The positive electrode plate, negative electrode plate, and secondary battery are manufactured in the same manner as in Example 1.

[0176] Cycle performance test The cycle performance test conditions of the secondary battery are as follows: At 25°C and 45°C, a 1C / 1C cycle charge-discharge test is performed on the secondary battery. The charge-discharge voltage range is 2.8V to 4.35V, and the test is terminated when the capacity drops to 80% of the initial discharge specific capacity (i.e., 80% SOH (state of health)). Here, SOH is the battery's health life indicating the percentage of the fully charged capacity of the secondary battery relative to the rated capacity. The SOH of a newly shipped secondary battery is 100%.

[0177] Table 1 shows the test results of the cycle performance test conducted on the secondary batteries manufactured in each of the above comparative examples and examples.

[0178]

Table 1

[0179] As can be seen from the cycle performance test data of the above examples and comparative examples, in electrolytes with different lithium salts, doping a reasonable ratio of sodium or potassium ions in situ at the lithium sites can effectively improve the cycle life of the battery. When the total ratio of dopant ions in the lithium salt is greater than the 0.5 coefficient, there are more dopant ions in the lithium salt, resulting in insufficient lithium retention, which causes insufficient lithium consumption in the middle and later stages of the cycle and reduces the cycle life of the battery.

[0180] By replacing some of the lithium sites in the lithium salt with sodium and potassium with larger ionic radii, sodium and potassium ions occupy the same spatial position as lithium ions, have the same energy level, have the same movement trajectory when the charge-discharge ions desorb, and the doped sodium or potassium ions can effectively prevent Li / Ni mixing in the layered cathode, further improving the cycle performance. On the other hand, sodium ions, potassium ions, etc. in the alkali metal double salt help to increase the content of organic lithium in the SEI during the SEI film formation process of the first charge-discharge.

[0181] It should be noted that this application is not limited to the above embodiments. The above embodiments are exemplary, and any embodiments that have a configuration substantially the same as the technical idea within the scope of the technical solution of this application and exhibit the same effects are included within the technical scope of this application. In addition, within the scope not departing from the spirit of this application, various modifications that can be conceived by those skilled in the art to the embodiments, and other forms constructed by combining some of the components in the embodiments are also included within the scope of this application.

Description of Reference Numerals

[0182] 1: Battery pack, 2: Upper housing, 3: Lower housing, 4: Battery module, 5: Secondary battery, 51: Case, 52: Electrode assembly, 53: Cover plate, 6: Power consumption device

Claims

1. An electrolytic solution comprising an organic solvent and an electrolyte salt dissolved in the organic solvent, wherein the electrolyte salt contains an alkali metal double salt containing lithium ions and at least one other alkali metal ion other than lithium ions, and the electrolytic solution is characterized by this.

2. The electrolytic solution according to Claim 1, wherein the other alkali metal ions in the alkali metal double salt include sodium ions and potassium ions.

3. The electrolytic solution according to Claim 1 or 2, wherein the alkali metal double salt contains sodium ions and potassium ions simultaneously.

4. The alkali metal double salt is Li ａ Na ｂ K ｃ PF ６ 、Li ａ Na ｂ K ｃ BOB, Li ａ Na ｂ K ｃ ODFB, Li ａ Na ｂ K ｃ TFOP, Li ａ Na ｂ K ｃ PO ２ F ２ 、Li ａ Na ｂ K ｃ TFSI, Li ａ Na ｂ K ｃ FSI and Li ａ Na ｂ K ｃ contains one or more of BODFP, The electrolytic solution according to any one of Claims 1 to 3, wherein a + b + c = 1 and 0.5 ≤ a < 1.

5. The electrolyte salt contains a base lithium salt, The base lithium salt is LiPF ６ , LiBOB, LiODFB, LiTFOP, LiPO ２ F ２ , LiTFSI, LiFSI and one or more of LiBODFP, and the electrolytic solution according to any one of claims 1 to 4, characterized in that it contains the same.

6. The mass ratio of the base lithium salt to the alkali metal double salt in the electrolyte salt is X:1, and the electrolytic solution according to Claim 5 is characterized in that 0.65 ≤ X < 1.

7. The electrolytic solution according to Claim 6 is characterized in that 0.7 ≤ X < 0.

9.

8. The electrolytic solution according to any one of Claims 5 to 7, wherein the types of anions of the base lithium salt and the alkali metal double salt are the same.

9. The electrolytic solution according to any one of Claims 1 to 8, wherein the concentration of the electrolyte salt in the electrolytic solution is 0.5 mol / L to 2 mol / L.

10. The organic solvent contains one or more of dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethylene carbonate, propylene carbonate, and diethyl carbonate, and the electrolytic solution according to any one of Claims 1 to 9 is characterized by this.

11. A secondary battery comprising the electrolytic solution according to any one of Claims 1 to 10, and the secondary battery is characterized by this.

12. The positive electrode active material in the positive electrode plate of the secondary battery is a positive electrode active material having a layered structure, and the secondary battery according to Claim 11 is characterized by this.

13. A battery module comprising the secondary battery according to Claim 11 or 12, and the battery module is characterized by this.

14. A battery pack comprising the battery module according to Claim 13, and the battery pack is characterized by this.

15. A power consumption device, characterized by including at least one of the secondary battery according to claim 11 or 12, the battery module according to claim 13, or the battery pack according to claim 14.

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