Electrolytes, secondary batteries, battery modules, battery packs, and power consumption devices

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] This application relates to the field of secondary battery technology, and more particularly to electrolytes, secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] In recent years, as the range of applications for ion-based secondary batteries has expanded, they are widely used in energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in many fields including power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the remarkable development of secondary batteries, there is a growing demand for higher cycle life in ion-based secondary batteries.

[0003] As the demand for energy density increases, the materials used in ternary cathodes have progressed from early low-nickel materials to current high-nickel materials, depending on the demand and design. However, the overall lifespan of high-nickel materials is inferior. This is because, on the one hand, the increased nickel content leads to more lithium nickel mixing and inflow, reducing the battery's cycle life. On the other hand, in conventional solid electrolyte interphase (SEI) films on electrode surfaces using lithium salt electrolytes, the organic lithium content is low. Low organic lithium content leads to solvent molecule co-insertion, causing electrode material degradation and further reducing the cycle life of secondary batteries.

[0004] The electrolyte is a crucial component of secondary batteries. It determines the composition and structure of the SEI film, significantly impacting the stability of the electrode structure and the cycle life of the secondary battery. Optimizing the design of the electrolyte is a primary means of improving the cycle life of secondary batteries. Therefore, seeking electrolytes that further enhance the cycle life of secondary batteries is a key research area for those skilled in the art. [Overview of the project]

[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 PF6, 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 PO2F2, Li a Na b K c TFSI, Li a Na b K c FSI and Li a Na b K c includes one or more of BODFP, a + b + c = 1, 0.5 ≤ a < 1.

[0010] In any embodiment, the electrolyte salt comprises a base lithium salt, the base lithium salt comprising one or more of LiPF6, LiBOB, LiODFB, LiTFOP, LiPO2F2, LiTFSI, LiFSI, and 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 molecular 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] A second aspect of this application provides a secondary battery containing an electrolyte according to the first aspect of this 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 with a layered structure.

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

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

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

[0021] The electrolyte of this application uses an alkali metal double salt containing lithium ions and at least one alkali metal ion other than lithium ions as the electrolyte salt. First, the radii of the alkali metal ions other than lithium in this alkali metal double salt (e.g., sodium ions, potassium ions) are larger than those of lithium, and during the initial discharge, they are inserted into a portion of the lithium sites of the layered positive electrode, thereby increasing the stability of the layered structure, preventing Li / Ni mixing in the layered positive electrode, and further improving the cycle performance of the secondary battery. Second, the sodium ions, potassium ions, etc. in the alkali metal double salt help to increase the organic lithium component in the SEI film during the SEI film formation process during the initial charge-discharge, and further effectively improve the co-intercalation of solvent molecules, avoiding damage to the electrode material due to the co-intercalation of solvent molecules, and significantly improving the cycle performance of the electrode. Furthermore, by substituting some lithium sites in the lithium salt with sodium or potassium salts, which have larger ionic radii, sodium and potassium ions can occupy the same spatial positions as lithium ions, and their energy levels are the same. The sodium and potassium ion structures occupying the in-situ lithium sites in the lithium salt become more stable, and lithium holes provide stable storage spaces for sodium and potassium. This reduces the efficiency of insertion and desorption of sodium and potassium ions to their corresponding lithium sites, which is advantageous for the more sustained action of sodium and potassium ions. Additionally, during ion desorption during charging and discharging, the ions maintain the same movement trajectory, quantitatively improving the cell's cycle life without introducing extra impurities or causing side reactions. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device in which a secondary battery is used as a power source according to one embodiment of this application. [Modes for carrying out the invention]

[0023] The following describes in detail embodiments of the electrolyte, secondary battery, battery module, battery pack, and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the subject matter described in the claims.

[0024] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is conceivable that this may be understood as the ranges 60-110 and 80-120. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, all of the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 are conceivable. In this application, unless otherwise specified, the numerical range “ab” represents an abbreviation for any combination of real numbers a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are listed herein, and "0 to 5" is merely an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0025] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0026] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0027] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. 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), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0028] Unless otherwise specified, the terms “includes” and “inclusion” as used in this application may be open or closed. For example, “includes” and “inclusion” may mean that other components not listed may be included or inclusion, or that only the listed components may be included or inclusion.

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

[0030] Currently, due to the remarkable advancements in secondary batteries, there are increasingly higher demands on their cycle performance. Secondary batteries with superior cycle performance place very high demands on the electrolyte. Therefore, seeking electrolytes that 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 higher energy density in secondary batteries, ternary cathode materials now largely employ high-nickel materials, which generally have a poor overall lifespan. On the other hand, increased nickel content leads to more lithium-nickel mixing, further reducing the cycle life of secondary batteries. Furthermore, conventional lithium salt electrolytes have a low organic lithium content in the SEI film, which easily causes co-intercalation of solvent molecules and damages the electrode material, further reducing the cycle life of secondary batteries.

[0032] The inventors have developed an electrolyte solution that uses an alkali metal double salt containing lithium ions and other alkali metal ions (e.g., sodium, potassium, etc.) as the electrolyte salt. This electrolyte solution can effectively improve the cycle performance of secondary batteries and extend their cycle life.

[0033] In some embodiments, a first aspect of this application provides an electrolyte comprising an organic solvent and an electrolyte salt dissolved in the organic solvent, wherein the electrolyte salt comprises an alkali metal double salt comprising lithium ions and at least one other alkali metal ion other than lithium ions.

[0034] The electrolyte of this 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 radii of the alkali metal ions other than lithium in this alkali metal double salt (e.g., sodium ions, potassium ions) are larger than those of lithium, and during the initial discharge process, they are inserted into a portion of the lithium sites of the layered positive electrode, thereby increasing the stability of the layered structure, preventing Li / Ni mixing of the layered positive electrode, and further improving the cycle performance of the secondary battery.

[0035] On the other hand, sodium ions, potassium ions, etc., in the alkali metal double salt help to increase the organolithium component in the SEI film during the initial charge-discharge SEI film formation process, and further effectively improve the co-intercalation of solvent molecules, thereby avoiding damage to the electrode material due to the co-intercalation of solvent molecules and significantly improving the cycle performance of the electrode.

[0036] When sodium salts, potassium salts, etc., are directly added to lithium salts to form electrolyte salts, the electrolyte manufacturing process requires additional introduction and purification processes via separate piping to introduce the sodium salts, potassium salts, etc., necessitating the introduction of additional equipment and increasing production costs. On the other hand, simply adding sodium salts and potassium salts to lithium salts releases a large amount of sodium and potassium ions into the electrolyte. These sodium and potassium ions are not bound by ionic bonds, resulting in significant irregular ionic movement, making it difficult to quantitatively control the improvement of the SEI film. Furthermore, simply adding sodium salts and potassium ion salts introduces excess anions. In the same solvent, the type of metal salt alters the thermodynamic stability and solvation structure of the electrolyte, affecting its decomposition behavior, and further changing the interface properties between the electrode and the electrolyte, as well as the electrochemical performance of the electrode. If different anions have different electronegativity, the anions enter the solvation layer, participate in solvation structure reactions, accelerate the decomposition of the electrolyte, and cause irreversible losses.

[0037] This application employs the method of substituting some lithium sites in a lithium salt with alkali metal double salts such as sodium and potassium salts, which have larger ionic radii. Compared to the method of directly adding sodium and potassium salts to a lithium salt, sodium and potassium ions in alkali metal double salts can occupy the same spatial positions as lithium ions, have the same energy levels, and the sodium and potassium ion structures occupying the in-situ lithium sites in the lithium salt are more stable. Lithium holes provide stable spaces for sodium and potassium storage, reducing the efficiency of detachment and insertion of sodium and potassium ions into their corresponding lithium sites, which is advantageous for the sustained action of sodium and potassium ions. Furthermore, when ions detach during charging and discharging, they have the same migration trajectory, quantitatively improving the cycle life of secondary batteries, without introducing extra impurities or causing side reactions.

[0038] In some embodiments, the other alkali metal ions in the alkali metal double salt include sodium and potassium ions. For clarity, other alkali metal ions include rubidium and cesium ions.

[0039] In some embodiments, the alkali metal double salt contains both sodium and potassium ions. 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 and potassium ions.

[0040] In some embodiments, the alkali metal double salt is Li a Na b K c PF6, Li a Na b K c BOB, Li a Na b K c ODFB, Li a Na b K c TFOP, Li a Nab K c PO2F2, Li a Na b K c TFSI, Li a Na b K c FSI and Li a Na b K c It contains one or more of the BODFPs, 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 represent the number of atoms of lithium, sodium, and potassium in the above alkali metal double salt molecular formula, respectively.

[0041] The above "0.5 ≤ a < 1" includes the minimum and maximum values ​​within that range, as well as the values ​​between the minimum and maximum values. Specific examples include, but are not limited to, the values ​​in the example and 0.6, 0.7, 0.8, and 0.9.

[0042] In any embodiment, the electrolyte salt also includes a base lithium salt, which includes one or more of LiPF6, LiBOB, LiODFB, LiTFOP, LiPO2F2, LiTFSI, LiFSI, and LiBODFP. Thus, the electrolyte salt contains both an alkali metal double salt and a base lithium salt. In other embodiments, the electrolyte salt may contain only an alkali metal double salt, and the base lithium salt may not be included.

[0043] Furthermore, when an electrolyte salt contains both an alkali metal double salt and a base lithium salt, the anions in the alkali metal double salt are of the same type as the anions 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] The above "0.65 ≤ X < 1" includes, but is not limited to, the minimum and maximum values ​​within that range, and the values ​​between the minimum and maximum values. Specific examples include the values ​​in the example 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, and 0.98.

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

[0047] In any embodiment, the molecular concentration of the electrolyte salt in the electrolyte solution 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 contain any of the above organic solvents, or may contain two or more of the above organic solvents simultaneously.

[0049] A second aspect of this application provides a secondary battery comprising the electrolyte described in the first aspect of this application. As a result, the secondary battery has good cycle performance and a long cycle life.

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

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

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

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

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

[0055] In one embodiment of this 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 charging and discharging process of the battery, active ions are inserted and removed by moving back and forth between the positive and negative electrode plates. The electrolyte acts as a conductor of ions between the positive and negative electrode plates. The separator is placed between the positive and negative electrode plates and primarily serves to prevent short circuits between the positive and negative electrodes, while also 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 placed on at least one surface of the positive electrode current collector, the positive electrode film layer containing a positive electrode active material.

[0058] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

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

[0060] In some embodiments, the positive electrode active material may further comprise positive electrode active materials for batteries that are well known in the art. For example, the positive electrode active material may comprise at least one material from among lithium-containing phosphates with an olivine structure, 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 positive electrode active materials for batteries may also be used. These positive electrode active materials may be used individually or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (This can be abbreviated as LiNi) 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (This can be abbreviated as LiNi) 0.5 Co 0.25 Mn 0.25 O2(NCM 211(This can be abbreviated as LiNi) 0.6 Co 0.2 Mn 0.2 O2(NCM 622 (This can be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This may be abbreviated as LiNi) Lithium nickel cobalt aluminum oxide (for example, LiNi 0.85 Co 0.15 Al 0.05 It may include, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

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

[0062] In some embodiments, the positive electrode film layer optionally further comprises an adhesive. For example, the adhesive may comprise 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 cathode film layer optionally further comprises a conductive agent. For 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 cathode film layer is 0 to 20% by weight, based on the total weight of the cathode film layer.

[0064] In some embodiments, the positive electrode plate may be manufactured by the following method: The above components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, wherein the solid content of the positive electrode slurry is 40-80 wt%, and the viscosity at room temperature is adjusted to 5000-25000 mPa·s; the positive electrode slurry is coated onto the surface of the positive electrode current collector, dried, and then cold-pressed using a cold rolling mill to form the positive electrode plate, wherein the unit surface density of the positive electrode powder coating is 150-350 mg / cm³. 2 The compaction density of the positive electrode plate is 3.0-3.6 g / cm³. 3 Therefore, it can be optionally set to 3.3-3.5 g / cm³. 3 That is the case.

[0065] The formula for calculating the consolidated density is: Consolidation density = coating surface density / (plate thickness after pressing - current collector thickness)

[0066] (Negative electrode plate) The negative electrode plate includes a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, the negative electrode film layer containing a negative electrode active material.

[0067] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0068] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material on the polymer material substrate. Here, the metal material includes, but is not limited to, copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, and the polymer material substrate 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 be a negative electrode active material for batteries that is well known in the art. For example, the negative electrode active material may include at least one of materials such as artificial graphite, natural graphite, soft carbon, hard carbon, silicone-based materials, tin-based materials, and lithium titanate. The silicone-based material may be selected from at least one of elemental silicone, silicon oxide, silicone-carbon composites, silicone-nitrogen composites, and silicone alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used individually or in combination of two or more.

[0070] In some embodiments, the negative electrode film layer optionally further comprises 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 electrode film layer.

[0071] In some embodiments, the anode film layer optionally further comprises 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 anode film layer is 0 to 20% by weight, based on the total weight of the anode film layer.

[0072] In some embodiments, the negative electrode film layer optionally further comprises other additives, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)). The weight ratio of the other additives 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 a negative electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70 wt%, and the viscosity at room temperature is adjusted to 2000-10000 mPa·s. The obtained negative electrode slurry is then coated onto a negative electrode current collector, and after a drying process, it is subjected to a cold press, for example, a roll press, to obtain a negative electrode plate. The unit surface density of the negative electrode powder coating is 75-220 mg / m². 2 Therefore, the compaction density of the negative electrode plate is 1.2~2.0 g / m³. 3 That is the case.

[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 contains 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 PF6, 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 PO2F2, 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, and a + b + c = 1, 0.5 ≦ a < 1.

[0076] In some embodiments, the electrolyte salt also contains a base lithium salt, and the base lithium salt contains one or more of LiPF6, LiBOB, LiODFB, LiTFOP, LiPO2F2, LiTFSI, LiFSI and 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, and 0.65 ≦ X < 1.

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

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

[0080] (Separator) In some embodiments, the secondary battery further includes a separator. This application does not particularly limit the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0081] In some embodiments, the material of the separator may be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. If the separator is a multilayer 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 manufactured as an electrode assembly by a winding process or a lamination process.

[0084] In some embodiments, the secondary battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0085] In some embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics 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, rectangular, or any other shape. For example, Figure 1 shows a secondary battery 5 with a rectangular structure as an example.

[0087] In some embodiments, referring to Figure 2, the casing 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 side plates surround and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can close the housing 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 within the housing cavity. The electrolyte permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art can select according to the actual specific requirements.

[0088] In some embodiments, as shown in Figure 3, the secondary battery 5 may be assembled in a battery module 4, and the number of secondary batteries 5 included in the battery module 4 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 module 4.

[0089] In the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged according to any other method. Furthermore, the multiple secondary batteries 5 may be secured with fasteners.

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

[0091] In some embodiments, as shown in Figures 4 and 5, the battery module 4 may be further assembled into a 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 covering the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged inside the battery box in any manner.

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

[0094] The power consumption device 6 can be selected from a secondary battery 5, a battery module 4, or a battery pack 1 depending on the usage requirements.

[0095] Figure 4 shows an example of a power consumption device 6. This power consumption device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack 1 or battery module 4 can be used to meet the power consumption device 6's demand for high power and high energy density of the secondary battery 5.

[0096] Other examples of devices may include mobile phones, tablet computers, and laptop computers. These devices generally require lightweight designs and can use a secondary battery 5 as a power source.

[0097] Examples To further clarify the technical problem, technical solution, and beneficial effects that this application aims to solve, the application will be described in more detail below, linking the examples and drawings. It is clear that the examples described are only a selection of, and not all, examples of, this application. The description of at least one exemplary example below is for illustrative purposes only and does not limit this application or its applications. All other examples that can be obtained based on the examples of this application without creative effort by a person skilled in the art are all within the scope of protection of this application.

[0098] If specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in the art, or in the product instruction manual, shall be followed. Unless the manufacturer is specified for the reagents or instruments used, they are all common products available commercially.

[0099] Example 1 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 It is PF6. Prepare an electrolyte solution with a concentration of 1M. Here, the electrolyte salt Li 0.5 Na0.3 K 0.2 PF6 can be produced by the hydrogen fluoride solvent method, and the reaction process is as follows: (0.5LiF+0.3NaF+0.2KF)+PF5+CH3CN→Li 0.5 Na 0.3 K 0.2 (CH3CN)4PF6→Li 0.5 Na 0.3 K 0.2 PF6 Manufacturing of positive electrode plates for secondary batteries: 1) Polyvinylidene fluoride (PVDF), layered positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O2 and the conductive agent SuperP carbon black are mixed in a mass ratio of 90:5:5, and the amount of N-methylpyrrolidone (NMP) added as the solvent is adjusted to control the slurry viscosity from 100 mPa.s to 20000 mPa.s. This slurry is coated onto the positive electrode current collector using a coater or spray coater. After drying at 85°C, cold pressing is performed, followed by deburring, cutting, and slitting. The material is then dried for 4 hours under vacuum conditions at 85°C, and tabs are welded to produce a positive electrode plate for a secondary battery that meets the requirements.

[0100] Manufacturing of negative electrode plates for secondary batteries: The negative electrode active material graphite, conductive agent Super-P, thickener CMC, and adhesive SBR are mixed uniformly with the solvent deionized water in a mass ratio of 96.5:1.0:1.0:1.5 to produce a negative electrode slurry. The negative electrode slurry is applied to the copper foil current collector and dried at 85°C. After deburring, cutting, and slitting, it is further dried for 4 hours under vacuum conditions at 110°C, and tabs are welded to produce a secondary battery negative electrode plate that meets the requirements.

[0101] Manufacturing of secondary batteries: A 12μm polypropylene film is used as a separator. The positive electrode plate, separator, and negative electrode plate are stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation. The film is then wound up to obtain a rectangular bare cell. The bare cell is wrapped in aluminum foil, injected with electrolyte, vacuum-sealed, and subjected to multiple charge-discharge cycles to complete the manufacturing of the secondary battery.

[0102] Example 2 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 It is BOB. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: Li 0.5 Na 0.3 K 0.2 BOB can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 This is ODFB. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: Li 0.5 Na 0.3 K 0.2 ODFB can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 This is TFOP. Prepare an electrolyte solution with a concentration of 1 M. Electrolyte salt: Li 0.5 Na0.3 K 0.2 TFOP can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 It is PO2F2. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: Li 0.5 Na 0.3 K 0.2 PO2F2 can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 It is TFSI. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 This is FSI. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.3 K 0.2 This is BODFP. Prepare an electrolyte solution with a concentration of 1M. Electrolyte salt: 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.7 Na 0.2 K 0.1 It is PF6. Prepare an electrolyte solution with a concentration of 1M. Here, the electrolyte salt Li 0.7 Na 0.2 K 0.1PF6 can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.8 Na 0.1 K 0.1 It is PF6. Prepare an electrolyte solution with a concentration of 1M. Here, the electrolyte salt Li 0.8 Na 0.1 K 0.1 PF6 can be produced 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.9 Na 0.05 K 0.05 It is PF6. Prepare an electrolyte solution with a concentration of 1M. Here, the electrolyte salt Li 0.9 Na 0.05 K 0.05 PF6 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiPF6 and Li 0.5 Na 0.3 K 0.2 It is PF6. LiPF6 and Li 0.5 Na 0.3 K 0.2 The mass ratio of PF6 is 0.7:1, and it is prepared as 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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiBOB and Li 0.5 Na 0.3 K 0.2 It's BOB. LiBOB and Li 0.5 Na 0.3 K 0.2 The mass ratio of BOB is 0.8:1, and the electrolyte is prepared at 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiODFB and Li 0.5 Na 0.3 K 0.2 It is ODFB. LiODFB and Li 0.5 Na 0.3 K 0.2The mass ratio with ODFB is 0.9:1, and the electrolyte is prepared at 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 It is PF6. Prepare an electrolyte solution with a concentration of 1M.

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

[0130] Example 16 Preparation of the electrolyte for secondary batteries: A mixture of dimethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate is used as an organic solvent. Here, 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 It is BOB. Prepare an electrolyte solution 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 Preparation of the electrolyte for secondary batteries: A mixture of methyl formate, methyl acetate, and methyl butyrate is used as an organic solvent, with the mass ratio of each component being methyl formate:methyl acetate:methyl butyrate = 30:20:30. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 This is ODFB. Prepare an electrolyte solution with a concentration of 1.5 M.

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

[0134] Example 18 Preparation of the electrolyte for secondary batteries: A mixture of ethyl propionate, ethylene carbonate, and propylene carbonate is used as an organic solvent, with the mass ratio of each component being ethyl propionate:ethylene carbonate:propylene carbonate = 30:20:50. The electrolyte salt in the electrolyte is Li 0.5 K 0.5 It is TFOP. Prepare an electrolyte solution 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 It is PO2F2. Prepare an electrolyte solution with a concentration of 0.8 M.

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

[0138] Example 20 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 It is TFSI. Prepare an electrolyte solution 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li 0.5 K 0.5 This is FSI. Prepare an electrolyte solution with a concentration of 1M.

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

[0142] Example 22 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li 0.5 Na 0.5 This is BODFP. Prepare an electrolyte solution 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 20:20:40. The electrolyte salt in the electrolyte is Li 0.7 K 0.3 It is PF6. Prepare 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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with the mass ratio of each component being EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li0.8 Na 0.2 It is PF6. Prepare an electrolyte solution with a concentration of 1M.

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

[0148] Example 25 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.9 K 0.1 It is PF6. Prepare an electrolyte solution with a concentration of 1M.

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

[0150] Example 26 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiPF6 and Li 0.5 Na 0.5 It is PF6. LiPF6 and Li 0.5 Na 0.5 The mass ratio of PF6 is 0.7:1. Prepare an electrolyte solution with a concentration of 1 M.

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

[0152] Example 27 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiBOB and Li 0.5 K 0.5 It's BOB. LiBOB and Li 0.5 K0.5 The mass ratio of BOB is 0.8:1. Prepare an electrolyte solution with a concentration of 1 M.

[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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiPF6, and the electrolyte is prepared to a concentration of 1 M.

[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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiBOB, and the electrolyte is prepared to a concentration of 1 M.

[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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiODFB. Prepare an electrolyte solution 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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiTFOP. Prepare an electrolyte solution 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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiPO2F2. Prepare an electrolyte solution with a concentration of 1M.

[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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiTFSI. Prepare an electrolyte solution with a concentration of 1 M.

[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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiFSI. Prepare an electrolyte solution with a concentration of 1 M.

[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 Preparation of electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is LiBODFP. Prepare an electrolyte solution with a concentration of 1 M.

[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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salt in the electrolyte is Li 0.4 Na 0.5 K 0.1 It is PF6, and an electrolyte solution with a concentration of 1M is prepared.

[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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. All electrolyte salts in the electrolyte are lithium. 0.3 Na 0.3 K 0.4 It is PF6, and an electrolyte solution with a concentration of 1M is prepared.

[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 Preparation of the electrolyte for secondary batteries: A mixture of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) is used as an organic solvent, with a mass ratio of EC:PC:DEC = 30:30:40. The electrolyte salts in the electrolyte are LiPF6 and Li 0.5 Na 0.3 K 0.2 There is PF6. LiPF6 and Li 0.5 Na 0.3 K 0.2 The mass ratio of PF6 is 0.4:1, and an electrolyte solution with a concentration of 1 M is prepared.

[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 for secondary batteries are as follows: A 1C / 1C cycle charge-discharge test is performed on the secondary battery at 25°C and 45°C, with a charge-discharge voltage range of 2.8V to 4.35V. The test is stopped when the capacity drops to 80% of the initial discharge ratio capacity (i.e., 80% SOH (state of health)). Here, SOH is the battery's health life, representing the percentage of the secondary battery's fully charged capacity relative to its rated capacity. The SOH of newly shipped secondary batteries is 100%.

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

[0178] [Table 1]

[0179] As can be seen from the cycle performance test data of the above examples and comparative examples, doping the lithium sites in lithium in a reasonable ratio with sodium or potassium ions in different lithium salt electrolytes can effectively improve the battery's cycle life. When the sum of the proportions of dopant ions in the lithium salt is greater than a coefficient of 0.5, there are too many dopant ions in the lithium salt, resulting in insufficient Li content. This causes a shortage of lithium consumption in the mid-to-late cycle, reducing the battery's cycle life.

[0180] By substituting some lithium sites in a lithium salt with sodium and potassium ions, which have larger ionic radii, the sodium and potassium ions occupy the same spatial positions as lithium ions, have the same energy levels, and exhibit the same migration trajectory during charge-discharge ion desorption. Doped sodium or potassium ions can effectively prevent Li / Ni mixing in the layered cathode and further improve cycle performance. On the other hand, sodium and potassium ions in alkali metal double salts help increase the organic lithium component in the SEI film during the SEI film formation process in the initial charge-discharge stage.

[0181] It should be noted that this application is not limited to the embodiments described above. The embodiments described above are illustrative, and any embodiment that has substantially the same configuration as the technical idea and produces the same effects within the scope of the technical proposal of this application is included within the scope of the technical proposal. Furthermore, other forms constructed by combining some of the components of the embodiments, with various modifications that a person skilled in the art could conceive of, are also included within the scope of this application, as long as they do not depart from the spirit of this application. [Explanation of Symbols]

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

Claims

1. An electrolyte comprising 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. The electrolyte salt comprises a base lithium salt, The base lithium salt includes one or more of the following: LiPF6, LiBOB, LiODFB, LiTFOP, LiPO2F2, LiTFSI, LiFSI, and LiBODFP. The mass ratio of the base lithium salt to the alkali metal double salt in the electrolyte salt is X:

1. An electrolyte characterized by the condition 0.65 ≤ X < 1.

2. The electrolyte according to claim 1, characterized in that the other alkali metal ions in the alkali metal double salt include sodium ions and potassium ions.

3. The electrolyte according to claim 1, characterized in that 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 includes one or more of BODFP, The electrolyte according to any one of claims 1 to 3, characterized in that a + b + c = 1 and 0.5 ≤ a < 1.

5. The electrolyte according to claim 1, characterized in that 0.7 ≤ X < 0.

9.

6. The electrolyte according to claim 1, characterized in that the base lithium salt and the alkali metal double salt have the same anion type.

7. The electrolyte according to any one of claims 1 to 3, characterized in that the concentration of the electrolyte salt in the electrolyte is 0.5 mol / L to 2 mol / L.

8. The electrolyte according to any one of claims 1 to 3, characterized in that the organic solvent contains one or more of the following: dimethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethylene carbonate, propylene carbonate, and diethyl carbonate.

9. A secondary battery characterized by comprising an electrolyte according to any one of claims 1 to 3.

10. The secondary battery according to claim 9, characterized in that the positive electrode active material in the positive electrode plate of the secondary battery is a positive electrode active material with a layered structure.

11. A battery module characterized by including the secondary battery described in claim 9.

12. A battery pack, characterized by including the battery module described in claim 11.

13. A power consumption device, characterized in that it includes the battery pack described in claim 12.

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