Electrolyte additive, electrolyte and battery

Abstract

The invention discloses an electrolyte additive, an electrolyte and a battery, the electrolyte additive comprises a first additive and a second additive, the first additive comprises a compound shown as a formula 1: # imgabs0 #, R1 and R2 are respectively and independently selected from at least one of H, phenyl, halogen, C1-C6 alkyl, C1-C6 halogenated alkyl and # imgabs1 #, and R1 and R2 are not H at the same time; r3, R4 and R5 are respectively and independently selected from at least one of C1-C3 alkylene groups, oxygen atoms, O = S = O, C = O and S = O, at least one of R3, R4 and R5 is selected from O = S = O, C = O and S = O, and at least one of R3, R4 and R5 is selected from oxygen atoms; and the second additive comprises a compound shown as a formula 2: # imgabs2. The electrolyte additive is added into the electrolyte of the battery, so that the fast charging performance of the battery can be improved, and the high-temperature cycle performance can be improved.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and specifically, to electrolyte additives, electrolytes, and batteries. Background Art

[0002] With the development of new energy vehicles, consumers' demand for power sources and energy storage is also increasing day by day. Secondary batteries such as lithium-ion batteries and sodium-ion batteries are gradually replacing traditional batteries such as lead-acid batteries and are widely used in the fields of electronics, new energy vehicles, and energy storage. Although lithium-ion batteries have achieved commercial success, the fast charging performance and service life of lithium-ion batteries still need to be further improved to meet users' fast charging and long endurance requirements.

[0003] As an important component of secondary batteries, electrolytes play a key role in improving performance. However, in current high-energy-density batteries during fast charging cycles, the temperature inside the battery rises rapidly, deteriorating the rate charging performance of the battery, and the battery performance decays more quickly under high-temperature cycling conditions, thereby affecting the service life of the battery.

[0004] Therefore, there is an urgent need to develop a battery with excellent high-rate charging performance and good high-temperature cycling. Summary of the Invention

[0005] The present invention aims to at least partly alleviate or solve at least one of the above-mentioned problems.

[0006] In one aspect of the present invention, the present invention provides an electrolyte additive. In some embodiments of the present invention, the electrolyte additive includes a first additive and a second additive, and the first additive includes a compound represented by Formula 1:

[0007]

[0008] Wherein, R1 and R2 are each independently selected from at least one of H, phenyl, halogen, C1-C6 hydrocarbon group, C1-C6 halogenated hydrocarbon group, and R1 and R2 are not both H at the same time; R3, R4, and R5 are each independently selected from at least one of C1-C3 alkylene group, oxygen atom, O=S=O, C=O, and S=O, at least one of R3, R4, and R5 is selected from O=S=O, C=O, and S=O, and at least one of R3, R4, and R5 is selected from oxygen atom;

[0009] The second additive includes a compound represented by Formula 2:

[0010] Thus, by adding the above electrolyte additive to the electrolyte of the battery, the fast charging performance of the battery can be improved, and the high-temperature cycling performance can be enhanced.

[0011] In some embodiments of the present invention, the first additive includes at least one of the following substances:

[0012]

[0013] The above-mentioned first additive can be preferentially reduced at the negative electrode to form a good SEI film, thereby inhibiting the co-insertion and reduction of solvent molecules on the negative electrode. Moreover, it can be preferentially oxidized at the positive electrode to form a good CEI film, thereby inhibiting the oxidative decomposition of electrolyte components on the positive electrode, and thus inhibiting the reaction of the electrolyte at the interface, especially reducing the degree of reaction intensification caused under high-temperature conditions.

[0014] In some embodiments of the present invention, in the electrolyte additive, the mass ratio of the first additive to the second additive is (0.25 - 10):1. Thereby, it is beneficial to further improve the fast charging performance and high-temperature cycling performance of the battery.

[0015] On the other hand of the present invention, the present invention provides an electrolyte. In some embodiments of the present invention, the electrolyte includes the aforementioned electrolyte additive. Thus, this electrolyte has all the characteristics and advantages of the aforementioned electrolyte additive, which will not be elaborated herein. Generally speaking, using this electrolyte in a battery can inhibit the increase in battery impedance during cycling, and improve the fast charging performance and high-temperature cycling performance of the battery.

[0016] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass fraction of the first additive is 0.1% - 5%, and can be optionally 0.5% - 2%. The first additive with the above content can form SEI and CEI films with excellent quality, and can more effectively slow down the interfacial reaction, thereby effectively improving the high-temperature cycling performance of the battery.

[0017] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass fraction of the second additive is 0.1% - 3%, and can be optionally 0.2% - 2%. The second additive with the above content can effectively reduce the initial impedance of the battery and inhibit the increase in battery impedance during cycling, thereby improving the fast charging performance of the battery.

[0018] In some embodiments of the present invention, the electrolyte further includes a solvent and an electrolyte salt. Based on the total mass of the electrolyte, the mass fraction of the electrolyte salt is 12% - 18%, and can be optionally 12% - 16%; based on the total mass of the electrolyte, the mass fraction of the solvent is 69% - 87.2%. The contents of the solvent and the electrolyte salt meeting the above conditions are beneficial to improving the overall performance of the battery.

[0019] In some embodiments of the present invention, the solvent includes at least one of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, and methyl propionate. The above solvents can maintain good stability during the charge and discharge cycles, which is beneficial to improving the fast charging and high-temperature cycle performance of the battery.

[0020] In some embodiments of the present invention, the electrolyte further includes a third additive, and the third additive includes at least one of a high-temperature type additive, a negative electrode film-forming additive, and a water and acid removal additive. The mass ratio of the third additive is 0.1%-5%. Thereby, it is beneficial to further improve the fast charging and high-temperature cycle performance of the battery.

[0021] In some embodiments of the present invention, the high-temperature type additive includes at least one of 1,3-propane sultone, 1,3-propene sulfonic acid lactone, ethylene sulfate, ethylene sulfite, and tetravinylsilane.

[0022] In some embodiments of the present invention, the negative electrode film-forming additive includes at least one of vinylene carbonate and ethylene vinylene carbonate.

[0023] In some embodiments of the present invention, the water and acid removal additive includes at least one of tris(trimethylsilyl) borate, tris(trimethylsilyl) phosphate, and tris(ethenyldimethylsilyl) phosphate. Thereby, it is beneficial to further improve the fast charging and high-temperature cycle performance of the battery.

[0024] In another aspect of the present invention, the present invention provides a battery. In some embodiments of the present invention, the battery includes the electrolyte described above. Thereby, the battery has all the characteristics and advantages of the electrolyte described above, which will not be elaborated here.

[0025] In some embodiments of the present invention, the battery is a lithium-ion battery.

[0026] In some embodiments of the present invention, the electrolyte salt in the electrolyte of the lithium-ion battery includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0027] In some embodiments of the present invention, the electrolyte of the lithium-ion battery further includes a lithium salt additive, and the lithium salt additive includes at least one of lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluorodioxalate phosphate, lithium tetrafluoroborate, lithium tetrafluoro(oxalato)phosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium trifluoromethanesulfonate, and lithium difluorophosphate.

[0028] In some embodiments of the present invention, the lithium-ion battery includes a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes LiNi 0.5 Mn 1.5 O4, LiMn2O4, Li 1+a Mn 1-x M 1 x O2, LiCo 1- y M 2 y O2, LiFe 1-z M 3 z PO4, Li2Mn 1-b O4, M 1 , M 2 , M 3 each independently includes one or more of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B, F, 0 ≤ a < 0.2, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ b < 1.

[0029] In some embodiments of the present invention, the battery is a sodium-ion battery.

[0030] In some embodiments of the present invention, the electrolyte salt in the electrolyte of the sodium-ion battery includes at least one of sodium hexafluorophosphate and sodium bis(fluorosulfonyl)imide.

[0031] In some embodiments of the present invention, the electrolyte of the sodium-ion battery further includes a sodium salt additive, and the sodium salt additive includes at least one of sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, and sodium difluorophosphate. Detailed Description of Embodiments

[0032] Embodiments of the present invention will be described in detail below. The following described embodiments are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0033] In one aspect of the present invention, the present invention provides an electrolyte additive. In some embodiments of the present invention, the electrolyte additive may include a first additive and a second additive. The first additive may include a compound represented by Formula 1: Formula 1, wherein R1 and R2 each independently selected from H, phenyl, halogen, C1-C6 hydrocarbon group, C1-C6 halogenated hydrocarbon group, at least one of them, R1 and R2 are not both H at the same time; R3, R4 and R5 are each independently selected from at least one of C1-C3 alkylene, oxygen atom, O=S=O, C=O and S=O, at least one of R3, R4 and R5 is selected from O=S=O, C=O and S=O, and at least one of R3, R4 and R5 is selected from oxygen atom.

[0034] The second additive may include a compound represented by Formula 2:

[0035] For a lithium-ion battery, the second additive can effectively improve the film-forming components of the SEI and CEI. Due to its complex structure containing elements such as F, P, and S, it will combine with Li to form inorganic components such as LiF, LiSO3, and P=O anion groups during the film-forming stage, which can effectively reduce the initial impedance of the battery and inhibit the increase in impedance during the cycling process, and improve the conduction rate of lithium ions in the SEI and CEI, thereby enhancing the fast-charging performance of the battery. However, since the interfacial film formed by the second additive has more inorganic components, it may affect its film-forming stability under high-temperature cycling. Therefore, adding the first additive can effectively improve the film-forming components and enhance the high-temperature stability of the film-forming. Due to its relatively low LUMO (lowest unoccupied molecular orbital) energy level, the first additive can be preferentially reduced on the negative electrode side to form a good SEI (solid electrolyte interface), thereby inhibiting the co-insertion and reduction of solvent molecules on the negative electrode. At the same time, the first additive has a relatively high HOMO (highest occupied molecular orbital) energy level, which can be preferentially oxidized on the positive electrode side to form a good CEI (cathode-electrolyte interface), and the formed ROSO3Li / ROSO2Li, Li2SO4 / Li2SO3 replace alkyl lithium carbonate to become the main components of the SEI and CEI, making the interfacial film more tough and maintaining a relatively stable structure at high temperatures, thereby improving the high-temperature cycling performance of the battery.

[0036] The mechanisms by which the first additive and the second additive improve the fast-charging performance and high-temperature cycling performance of lithium-ion batteries have been described in detail above. Adding the electrolyte additives containing the first additive and the second additive to the sodium-ion battery electrolyte can also improve the fast-charging performance and high-temperature cycling performance of the sodium-ion battery, and the mechanism of action is similar to that of lithium-ion batteries, which will not be elaborated here.

[0037] In some embodiments of the present invention, the first additive may include at least one of the following substances:

[0038]

[0039] In some embodiments, the second additive may be The above-mentioned second additive can effectively improve the film-forming components of the SEI film and the CEI film, increase the content of inorganic small molecules, thereby reducing the initial impedance of the battery and inhibiting the increase in battery impedance during the cycling process, and improving the fast charging performance of the battery.

[0040] In some embodiments of the present invention, in the electrolyte additive, the mass ratio of the first additive to the second additive can be (0.25-10):1. For example, the mass ratio of the first additive to the second additive can be 0.25:1, 0.5:1, 1:1, 3:1, 5:1, 8:1, 10:1, etc. Thereby, the initial impedance of the battery can be further reduced and the impedance increase during the cycling process can be inhibited, improving the fast charging performance and high-temperature cycling performance of the battery.

[0041] On the other hand of the present invention, the present invention provides an electrolyte. In some embodiments of the present invention, the electrolyte may include the above-mentioned electrolyte additive. Thus, the electrolyte has all the characteristics and advantages of the above-mentioned electrolyte additive, which will not be elaborated here.

[0042] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass proportion of the first additive can be 0.1%-5%, that is, every 100 grams of the electrolyte contains 0.1g-5g of the first additive. Specifically, the mass proportion of the first additive can be selected from 0.1%, 0.2%, 0.5%, 1%, 3%, 5% or the range composed of any two of them. It can effectively improve the film-forming quality and enhance the high-temperature stability of SEI and CEI, thereby improving the high-temperature cycling performance.

[0043] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass proportion of the first additive can be 0.5%-2%. For example, the mass proportion of the first additive can be 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.7% or 2%. Thereby, the film-forming quality can be significantly improved and the high-temperature cycling performance of the battery can be enhanced. If the content of the first additive is lower than this range, the improvement of the film-forming effect is not obvious and the improvement of the high-temperature cycling is not obvious. Higher than this range may cause too large an increase in battery impedance, affecting the fast charging performance of the battery.

[0044] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass ratio of the second additive can be 0.1%-3%, that is, every 100 grams of the electrolyte includes 0.1g-3g of the second additive. Specifically, the mass ratio of the second additive can be selected from 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3% or the range composed of any two of them. Thereby, the impedance can be reduced and the fast charging performance of the battery can be improved. If the content of the second additive is lower than this range, the effect of improving the impedance is not obvious and the improvement of the fast charging performance is not obvious. Higher than this range may cause a counter-effect and have a negative impact on the impedance.

[0045] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass ratio of the second additive can be 0.2%-2%. For example, the mass ratio of the second additive can be 0.2%, 0.3%, 0.5%, 0.8%, 1.0%, 1.3%, 1.4%, 1.7% or 2%. The impedance of the battery can be significantly reduced and the fast charging performance of the battery can be significantly improved.

[0046] In some embodiments of the present invention, the electrolyte may further include a solvent. Based on the total mass of the electrolyte, the mass ratio of the solvent can be 50%-85%. For example, the mass ratio of the solvent can be 50%, 55%, 60%, 65%, 70%, 75%, 80% or 85%.

[0047] In some embodiments of the present invention, the solvent may include at least one of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate. In some embodiments of the present invention, the solvent may include at least two of the above solvents.

[0048] In some embodiments of the present invention, the electrolyte may further include an electrolyte salt. Based on the total mass of the electrolyte, the mass ratio of the electrolyte salt can be 12%-18%, that is, every 100 grams of the electrolyte includes 12g-18g of the electrolyte salt. Specifically, the mass ratio of the electrolyte salt can be selected from 12%, 13%, 14%, 15%, 16%, 17%, 18% or the range composed of any two of them.

[0049] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass ratio of the electrolyte salt can be 12%-16%.

[0050] In some other embodiments of the present invention, the electrolyte may further include a third additive. The third additive may include at least one of a high-temperature type additive, a negative electrode film-forming additive, and a water and acid removing additive.

[0051] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass ratio of the third additive can be 0.1%-5%. For example, the mass ratio of the third additive can be 0.1%, 0.5%, 1%, 1.5%, 2%, 3%, 4% or 5%. When the content of the third additive is within the above range, it is beneficial to further improve the high-temperature cycling performance of the battery.

[0052] In some embodiments of the present invention, the high-temperature type additive can include at least one of 1,3-propane sultone, 1,3-propene sulfonic acid lactone, ethylene sulfate, ethylene sulfite, tetravinylsilane. The above additives can form organic components such as lithium alkyl sulfonate and silanes on the negative electrode sheet, improving the high-temperature stability of the SEI film, thereby improving the high-temperature cycling performance of the battery.

[0053] In some embodiments of the present invention, the negative electrode film-forming additive can include at least one of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate ethyl ester. The above additives can be reduced at the negative electrode prior to solvent molecules to form an SEI film, which is beneficial to further inhibit the co-insertion and reduction of solvent molecules on the negative electrode, and further effectively avoid the generation of reducing gases.

[0054] In some embodiments of the present invention, the water and acid removal additive can include at least one of tris(trimethylsilyl) borate, tris(trimethylsilyl) phosphate, tris(ethenyldimethylsilyl) phosphate. It can react with trace water in the battery, reduce the generation of HF, and inhibit the interfacial side reactions caused by moisture and HF.

[0055] In another aspect of the present invention, the present invention proposes a battery. In some embodiments of the present invention, the battery can include the electrolyte described above. Thus, the battery has good fast charging performance and high-temperature cycling performance.

[0056] In some embodiments of the present invention, the battery can be a lithium-ion battery.

[0057] In some embodiments of the present invention, the electrolyte salt in the electrolyte of the lithium-ion battery can include at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

[0058] In some embodiments of the present invention, the electrolyte of the lithium-ion battery can further include lithium salt additives, and the lithium salt additives can include at least one of lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium difluoro bis(oxalato)phosphate, lithium tetrafluoroborate, lithium tetrafluoro(oxalato)phosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate.

[0059] In some embodiments of the present invention, a lithium-ion battery may include a positive electrode sheet, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, the positive electrode active material layer may include a positive electrode active material, and the positive electrode active material may include LiNi 0.5 Mn 1.5 O4, LiMn2O4, Li 1+a Mn 1-x M 1 x O2, LiCo 1-y M 2 y O2, LiFe 1-z M 3 z PO4, Li2Mn 1-b O4, M 1 , M 2 , M 3 each independently includes one or more of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B, F, 0 ≤ a < 0.2, 0 ≤ x < 1, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ b < 1.

[0060] In some embodiments, 0 ≤ a ≤ 0.19, 0.05 ≤ a ≤ 0.15, 0.08 ≤ a ≤ 0.13, or, 0.1 ≤ a ≤ 0.12.

[0061] In some embodiments, 0 ≤ x ≤ 0.9, 0.1 ≤ x ≤ 0.8, 0.2 ≤ x ≤ 0.7, 0.3 ≤ x ≤ 0.6, or, 0.4 ≤ x ≤ 0.5.

[0062] In some embodiments, 0 ≤ y ≤ 0.9, 0.1 ≤ y ≤ 0.8, 0.2 ≤ y ≤ 0.7, 0.3 ≤ y ≤ 0.6, or, 0.4 ≤ y ≤ 0.5.

[0063] In some embodiments, 0 ≤ z ≤ 0.9, 0.1 ≤ z ≤ 0.8, 0.2 ≤ z ≤ 0.7, 0.3 ≤ z ≤ 0.6, or, 0.4 ≤ z ≤ 0.5.

[0064] In some embodiments, 0 ≤ b ≤ 0.9, 0.1 ≤ b ≤ 0.8, 0.2 ≤ b ≤ 0.7, 0.3 ≤ b ≤ 0.6, or, 0.4 ≤ b ≤ 0.5.

[0065] In some embodiments of the present invention, the positive electrode active material of the lithium-ion battery may include one or more of NCM, LiNi 0.5 Mn 1.5 O4, LiMn2O4, LiMnO2, Li2MnO4, LiFePO4.

[0066] In some embodiments of the present invention, the battery may be a sodium-ion battery.

[0067] The electrolyte salt in the electrolyte of the sodium-ion battery may include at least one of sodium hexafluorophosphate and sodium bis(fluorosulfonyl)imide.

[0068] In some embodiments of the present invention, the electrolyte of the sodium-ion battery may further include a sodium salt additive, and the sodium salt additive may include at least one of sodium bis(oxalato)borate, sodium difluoro(oxalato)borate, sodium tetrafluoroborate, and sodium difluorophosphate.

[0069] In some embodiments of the present invention, the sodium-ion battery may include a positive electrode sheet, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may include a polyanion material Na c M 4 d (X 1 e O f )X 2 g , where M 4 is a transition metal, X 1 is phosphorus, sulfur, silicon, tungsten, etc., and X 2 is at least one of F, OH, etc. In some specific embodiments, the positive electrode active material may include Na4Fe3(PO4)2(P2O7).

[0070] In some embodiments of the present invention, the battery may include a positive electrode sheet, a negative electrode sheet, a separator, and the aforementioned electrolyte. During the charge and discharge process of the battery, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows ions to pass through.

[0071] In some embodiments of the present invention, the positive electrode current collector may include a metal foil or a composite positive electrode current collector. For example, the metal foil may be made of aluminum foil. The composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. For example, the composite negative electrode current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as substrates like polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0072] In some embodiments of the present invention, the positive electrode active material layer of the positive electrode sheet may further optionally include a conductive agent. As an 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.

[0073] In some embodiments of the present invention, the positive electrode active material layer may further optionally include a binder. As an example, the binder 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 fluorinated acrylate resin.

[0074] In some embodiments of the present invention, the positive electrode sheet can be prepared in the following manner: Dispersing the positive electrode active material, conductive agent, and binder in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet can be obtained.

[0075] In some embodiments of the present invention, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer located on at least one surface of the negative electrode current collector, and the negative electrode active material layer may include a negative electrode active material.

[0076] In some embodiments of the present invention, the negative electrode current collector can be a metal foil or a composite current collector. For example, as an example, the metal foil can be a copper foil. 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 can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as substrates like polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0077] In some embodiments of the present invention, the negative electrode active material can be a negative electrode active material known in the art for batteries. As an example, the negative electrode active material may include at least one of the following materials: graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Among them, the silicon-based materials may include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys; the tin-based materials may include at least one of elemental tin, tin oxides, and tin alloys.

[0078] In some embodiments of the present invention, the negative electrode active material layer may further optionally include a binder, and the binder may include 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).

[0079] In some embodiments of the present invention, the negative electrode active material layer may further optionally include a conductive agent, and 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.

[0080] In some embodiments of the present invention, the negative electrode active material layer may further optionally include other additives, such as a thickening agent (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0081] In some embodiments of the present invention, the negative electrode plate can be prepared in the following manner: dispersing the negative electrode active material, the conductive agent, the binder, and any other components (such as a thickening agent) in a solvent (such as deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate can be obtained.

[0082] In the present invention, there is no particular limitation on the type of the separator. Those skilled in the art can select any well-known porous separator with good chemical stability and mechanical stability according to actual needs.

[0083] In some embodiments of the present invention, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride.

[0084] In some embodiments of the present invention, the thickness of the separator can be 10 μm - 12 μm, for example, 10 μm, 11 μm, 12 μm, etc.

[0085] The battery proposed by the present invention can be used in an electrical device or an energy storage device. Thus, the electrical device or the energy storage device has a long service life and good high-temperature resistance. In some embodiments of the present invention, the electrical device may include, but is not limited to, a mobile phone, a laptop computer, a pure electric vehicle, a hybrid electric vehicle, etc.

[0086] The present invention will be described below through specific embodiments. Those skilled in the art can understand that the following specific embodiments are only for the purpose of illustration and do not limit the scope of the present invention in any way. In addition, in the following embodiments, unless otherwise specified, the materials and equipment used are commercially available. If the specific processing conditions and methods are not clearly described in the following embodiments, the conditions and methods known in the art can be used for processing.

[0087] Example 1

[0088] 1. Preparation of the positive electrode sheet

[0089] The positive active material NCM613 (the molar ratio of Ni, Co, and Mn in the ternary material is 6:1:3), the conductive agent SuperP, and the binder polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone (NMP) in a mass ratio of 96:2:2 to form a positive electrode slurry (the solid content in the positive electrode slurry is 68 wt%, that is, the mass content of solids in the positive electrode slurry is 68%). The positive electrode slurry is coated on the upper and lower surfaces of the aluminum foil, dried, cold-pressed, and then trimmed, sliced, and slit to form a positive electrode sheet.

[0090] 2. Preparation of the negative electrode sheet

[0091] The negative active material graphite, the conductive agent conductive carbon black, the thickening agent carboxymethyl cellulose (CMC), and the binder styrene-butadiene rubber (SBR) are added to deionized water in a mass ratio of 95:1.5:1.5:2 to form a negative electrode slurry (the solid content in the negative electrode slurry is 49 wt%). The negative electrode slurry is coated on the upper and lower surfaces of the copper foil and dried, and then cold-pressed, trimmed, sliced, and slit to form a negative electrode sheet.

[0092] 3. Preparation of the electrolyte

[0093] In a high-purity argon glove box with an oxygen content and a water content both not higher than 0.1 ppm, an electrolyte additive including a first additive and a second additive is added to an organic solvent (in the organic solvent, the mass ratio of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) is EC:DMC:EMC = 3:3:4). After mixing evenly, lithium hexafluorophosphate (LiPF6) is slowly added (based on the total mass of the electrolyte, the mass ratio of LiPF6 is 13%). After the lithium salt is completely dissolved, the electrolyte is obtained.

[0094] 4. Separator

[0095] A polyethylene film with a thickness of 10 μm is used as the separator.

[0096] 5. Preparation of the lithium-ion battery

[0097] Stack the positive electrode sheet, separator, and negative electrode sheet in sequence, with the separator in the middle of the positive electrode sheet and the negative electrode sheet to isolate the positive electrode sheet and the negative electrode sheet, wind to obtain a bare battery cell, weld the electrode tabs, place the bare battery cell in the outer packaging, inject the prepared electrolyte into the dried battery cell, and complete the preparation of the lithium-ion battery through steps such as encapsulation, standing, formation, and shaping.

[0098] The differences between Examples 2-16, Comparative Examples 1 and 2 and Example 1 are recorded in Table 1, and the remaining parameters and steps are the same as those in Example 1.

[0099] Example 17

[0100] 1. Electrolyte preparation: Mix EC and EMC in a mass ratio of 3:7. After mixing, add sodium salt sodium hexafluorophosphate (NaPF6), the first additive, and the second additive according to the mass fraction of each component, and mix evenly to obtain the electrolyte.

[0101] 2. Positive electrode sheet preparation: Add the positive electrode material Na4Fe3(PO4)2(P2O7) (abbreviated as NFPP), conductive agent Super P (conductive carbon black), carbon nanotubes, and binder PVDF (polyvinylidene fluoride) to N-methylpyrrolidone in a mass ratio of 94.5:2.5:0.5:2.5, mix evenly, and stir under vacuum until it has a certain viscosity and uniform fluidity. Then, coat this slurry evenly on both sides of the aluminum foil, dry at 85°C, cold press, trim the edges, cut into sheets, cut into strips, and vacuum dry at 85°C for 10 hours. After welding the electrode tabs, a positive electrode sheet with a surface density of 33 mg / cm 2 is obtained.

[0102] 3. Negative electrode sheet preparation: Add the hard carbon negative electrode material, conductive agent Super P (conductive carbon black), thickener CMC (carboxymethyl cellulose sodium), and binder SBR (styrene-butadiene rubber) to deionized water in a mass ratio of 95:1.5:2.0:1.5, mix well to form a uniform slurry. After coating on both sides of the aluminum foil, dry at 85°C, then cold press, trim the edges, cut into sheets, cut into strips, and finally dry under vacuum at 85°C for 12 hours. After welding the electrode tabs, a negative electrode sheet with a surface density of 14.2 mg / cm 2 is obtained.

[0103] 4. Separator: Use a 9-μm-thick polyethylene porous polymer film as the substrate, and coat a 2-μm-thick adhesive coating on both sides of the substrate.

[0104] 5. Sodium-ion battery preparation:

[0105] The above positive electrode sheet, separator, and negative electrode sheet are stacked in sequence and then made into a bare battery cell with a theoretical capacity of 1000 mAh through a winding process. The bare battery cell is placed in an outer packaging aluminum foil and vacuum baked at 75 °C for 10 hours, and then the above electrolyte can be injected. After processes such as vacuum packaging, standing, formation, aging, and grading, the production of the sodium-ion battery is completed.

[0106] The differences between Examples 18 - 20, Comparative Examples 3 and 4 and Example 17 are recorded in Table 1, and the remaining parameters and steps are the same as those in Example 17.

[0107] Table 1

[0108]

[0109]

[0110] The batteries of each example and comparative example are tested, including DC impedance, fast charging performance, high-temperature cycle performance, etc., and the test results are recorded in Table 2. The test methods for lithium-ion batteries are as follows:

[0111] Test method for DC impedance (DCR): At 25 °C, charge at a constant current of 1C with constant voltage to 4.4V full charge, with a cut-off current of 0.05C. Discharge at a constant current of 1C for 30 min to 50% SOC, and after standing for 60 min, record the last voltage data point V1. Discharge at a constant current of 7C for 10S, and record the last voltage data point V2. The calculation method for DCR during 7C constant current discharge for 10S: DCR = (V1 - V2) / 7C.

[0112] Test method for fast charging cycle performance: At 25 °C, charge at a constant current of 5C with constant voltage to 4.4V, and after standing for 5 min, discharge at a constant current of 1C to 2.75V. Calculate the capacity retention rate after 500 cycles, and the calculation method: Capacity retention rate (%) = (Discharge capacity at the 500th time / Discharge capacity at the 1st time) × 100%.

[0113] Test method for high-temperature cycle performance: At 45 °C, charge at a constant current of 1C with constant voltage to 4.4V, and after standing for 5 min, discharge at a constant current of 1C to 2.75V. Calculate the capacity retention rate after 500 cycles, and the calculation method: Capacity retention rate (%) = (Discharge capacity at the 500th time / Discharge capacity at the 1st time) × 100%.

[0114] The test methods for sodium-ion batteries are as follows:

[0115] Test method for DC resistance (DCR): At 25°C, charge at a constant current and voltage of 1C until fully charged to 3.6V, with a cut-off current of 0.05C. Discharge at a constant current of 1C for 30 minutes until 50% SOC. After standing for 60 minutes, record the last voltage data point V1. Discharge at a constant current of 2C for 10 seconds, record the last voltage data point V2. The calculation method for DCR during 2C constant current discharge for 10 seconds: DCR = (V1 - V2) / 2C.

[0116] Test method for fast charge cycle performance: At 25°C, charge at a constant current and voltage of 5C until 3.6V, stand for 5 minutes, then discharge at a constant current of 2C until 1.5V. After 500 cycles, calculate the capacity retention rate. Calculation method: Capacity retention rate (%) = (Discharge capacity at the 500th cycle / Discharge capacity at the 1st cycle) × 100%.

[0117] Test method for high-temperature cycle performance: At 45°C, charge at a constant current and voltage of 1C until 3.6V, stand for 5 minutes, then discharge at a constant current of 1C until 1.5V. After 500 cycles, calculate the capacity retention rate. Calculation method: Capacity retention rate (%) = (Discharge capacity at the 500th cycle / Discharge capacity at the 1st cycle) × 100%.

[0118] Table 2

[0119]

[0120]

[0121] For lithium-ion batteries, as can be seen from Table 1 and Table 2, compared with Examples 1 - 16, in Comparative Examples 1 and 2, only the first additive or the second additive was added to the electrolyte, and the fast charge performance and high-temperature cycle performance of the lithium-ion batteries were both poor; compared with Examples 1, 2, 6, 7, and 13, the contents of the first additive and the second additive in Examples 3 - 5 and Examples 8 - 12 were more appropriate, and the fast charge performance and high-temperature cycle performance were also more excellent. In Examples 14 - 16, in addition to the first additive and the second additive, a third additive was also added, and the battery had excellent fast charge performance and high-temperature cycle performance.

[0122] For sodium-ion batteries, as can be seen from Table 1 and Table 2, in Comparative Examples 3 and 4, only the first additive or the second additive was added to the electrolyte. Compared with Examples 17 - 20, the DC resistance of the sodium-ion batteries in Comparative Examples 3 and 4 was larger, and the fast charge performance and high-temperature cycle performance were both poor. It can be seen that adding the first additive and the second additive to the electrolyte simultaneously can reduce the DC resistance of the sodium-ion battery, improve the fast charge performance and high-temperature cycle performance of the sodium-ion battery.

[0123] In the description of this specification, the descriptions referring to terms such as "some embodiments" and "other embodiments" mean that the specific features, structures, materials or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Additionally, it should be noted that in this specification, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0124] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electrolyte additive, characterized in that: The method comprises a first additive and a second additive, wherein the first additive comprises a compound represented by Formula 1: Wherein, R1 and R2 are each independently selected from H, phenyl, halogen, C1-C6 hydrocarbon group, C1-C6 halogenated hydrocarbon group, At least one of, R1 and R2 are not H at the same time; R3, R4 and R5 are each independently selected from at least one of a C1-C3 alkylene group, an oxygen atom, O=S=O, C=O and S=O, at least one of R3, R4 and R5 is selected from O=S=O, C=O and S=O, and at least one of R3, R4 and R5 is selected from an oxygen atom; The second additive includes a compound shown in Formula 2:

2. The electrolyte additive according to claim 1, characterized in that: The first additive includes at least one of the following substances:

3. The electrolyte additive according to claim 1 or 2, characterized in that: In the electrolyte additive, the mass ratio of the first additive to the second additive is (0.25-10):

1.

4. An electrolyte, characterized in that: The electrolyte additive comprises the electrolyte additive described in any one of claims 1 to 3.

5. The electrolyte according to claim 4, characterized in that Based on the total mass of the electrolyte, the mass proportion of the first additive is 0.1%-5%, and can be optionally 0.5%-2%.

6. The electrolyte according to claim 4, characterized in that Based on the total mass of the electrolyte, the mass proportion of the second additive is 0.1%-3%, and can be optionally 0.2%-2%.

7. The electrolyte according to any one of claims 4 to 6, characterized in that: It also includes a solvent and an electrolyte salt, and based on the total mass of the electrolyte, the mass proportion of the electrolyte salt is 12%-18%, and can be 12%-16%; Based on the total mass of the electrolyte, the mass proportion of the solvent is 69%-87.2%; Optionally, the solvent includes at least one of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, and methyl propionate.

8. The electrolyte according to claim 7, characterized in that It also includes a third additive, the third additive includes at least one of a high-temperature additive, a negative electrode film-forming additive, and a water-removing and acid-removing additive, and the mass proportion of the third additive is 0.1%-5%; Optionally, the high temperature additive includes at least one of 1,3-propane sultone, 1,3-propylene sultone, vinyl sulfate, vinyl sulfite, and tetravinylsilane; Optionally, the negative electrode film-forming additive includes at least one of vinylene carbonate and vinyl ethylene carbonate; Optionally, the water and acid removal additive includes at least one of tris(trimethylsilane)borate, tris(trimethylsilane)phosphate, and tris-(vinyldimethylsilane)phosphate.

9. A battery, characterized in that: The battery comprises the electrolyte according to any one of claims 4 to 8.

10. The battery according to claim 9, characterized in that The battery is a lithium-ion battery, Optionally, the electrolyte salt in the electrolyte of the lithium-ion battery includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide; Optionally, the electrolyte of the lithium-ion battery further includes a lithium salt additive, and the lithium salt additive includes at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorobis(oxalatophosphate), lithium tetrafluoroborate, lithium tetrafluorooxalatophosphate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethylsulfonyl)imide, lithium trifluoromethanesulfonate, and lithium difluorophosphate.

11. The battery according to claim 10, characterized in that The lithium-ion battery comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, wherein the positive electrode active material comprises LiNi 0.5 Mn 1.5 O4, LiMn2O4, Li 1+a Mn 1- x M 1 x O2、LiCo 1-y M 2 y O2、LiFe 1-z M 3 z PO4、Li2Mn 1-b O4, M 1 、M 2 、M 3 Each independently includes one or more of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B, and F, 0≤a<0.2, 0≤x<1, 0≤y<1, 0≤z<1, and 0≤b<1.

12. The battery according to claim 9, characterized in that The battery is a sodium ion battery, Optionally, the electrolyte salt in the electrolyte of the sodium ion battery includes at least one of sodium hexafluorophosphate and sodium bis(fluorosulfonyl)imide; Optionally, the electrolyte of the sodium ion battery further includes a sodium salt additive, and the sodium salt additive includes at least one of sodium bis(oxalatoborate), sodium difluorooxalatoborate, sodium tetrafluoroborate, and sodium difluorophosphate.

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