Electrolyte, battery, battery pack and electric equipment

Abstract

The invention provides an electrolyte, a battery, a battery pack and electric equipment, the electrolyte comprises azabowl-ene alkyl ammonium iodate, and the azabowl-ene alkyl ammonium iodate comprises a compound with a structure as shown in a formula 1. The electrolyte provided by the invention can inhibit lithium precipitation and self discharge of the battery, and improve the cycle life and other performances of the battery.

Description

Technical Field

[0001] This invention relates to an electrolyte, and more particularly to an electrolyte, a battery, a battery pack, and an electrical device, belonging to the field of ion batteries. Background Technology

[0002] Batteries are common electrochemical devices with wide applications. Electrolytes are a crucial component of batteries, affecting their performance, such as cycle life. However, batteries in this field generally suffer from serious self-discharge problems, easy lithium plating, and short cycle life, which urgently need to be addressed.

[0003] For example, the demand for secondary batteries using lithium iron phosphate and graphite as positive and negative electrode materials is rising sharply in the automotive and energy storage sectors. Simultaneously, the market is placing new and higher demands on energy storage cells—"long lifespan, high safety, and low cost," with "long lifespan" becoming a crucial indicator for evaluating the overall competitiveness of cells. Current market feedback indicates that the main reasons for accelerated cell lifespan degradation include lithium plating, transition metal dissolution, rapid electrolyte consumption, and cell self-discharge. Among these, lithium plating and self-discharge are the most common failure phenomena. Lithium plating leads to a rapid decrease in active lithium ions, accelerating electrolyte consumption and causing a rapid decline in cell capacity. Self-discharge exacerbates battery polarization, shortening battery life.

[0004] Therefore, developing an electrolyte that can suppress lithium plating and self-discharge in batteries and improve battery cycle life is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This invention provides an electrolyte that can suppress lithium plating and self-discharge in batteries, and improve battery cycle life and other performance characteristics.

[0006] The present invention provides a battery that is prepared based on the above-mentioned electrolyte and has high cycle performance.

[0007] The present invention provides a battery pack with excellent cycle performance.

[0008] This invention provides an electrical device with a long cycle life, which is beneficial for use in various scenarios.

[0009] This invention provides an electrolyte comprising azirene alkylammonium iodate, wherein the azirene alkylammonium iodate comprises a compound having the structure shown in Formula 1:

[0010]

[0011] In Formula 1, R is selected from H, halogen, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 fluoroalkyl, and R1 is selected from substituted or unsubstituted C1 to C10 alkyl.

[0012] The electrolyte as described above, wherein the compound having the structure shown in Formula 1 includes one or more of azirene methylammonium iodate, azirene ethylammonium iodate, azirene propylammonium iodate, and azirene butylammonium iodate.

[0013] In the electrolyte as described above, the mass percentage of the azirene alkylammonium iodate in the electrolyte is 0.1% to 5%.

[0014] The electrolyte as described above further includes a second additive, which includes one or more of vinylene carbonate, fluoroethylene carbonate, methylene disulfonate (MMDS), and vinyl sulfate (DTD).

[0015] In the electrolyte as described above, the mass percentage of the second additive in the electrolyte is 1.5% to 5%.

[0016] The electrolyte as described above further includes an organic solvent, the organic solvent comprising cyclic carbonates and / or linear carbonates; the cyclic carbonates comprising ethylene carbonate; and / or the linear carbonates comprising one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0017] The electrolyte as described above, wherein the electrolyte comprises a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.9 mol / L to 1.2 mol / L.

[0018] The electrolyte as described above, wherein the electrolyte comprises a lithium salt, the lithium salt comprising one or more of lithium hexafluorophosphate, lithium difluorosulfonate imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0019] The present invention also provides a battery comprising the electrolyte as described above.

[0020] The battery as described above includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes lithium manganese iron phosphate and / or ternary positive electrode materials.

[0021] The battery as described above includes a negative electrode sheet, which includes a negative electrode active material, which includes one or more of graphite, mesophase carbon microspheres, and silicon-carbon materials.

[0022] The present invention also provides a battery pack, wherein the battery described above is included.

[0023] The present invention also provides an electrical device, wherein the device includes a battery as described above or a battery pack as described above.

[0024] The electrolyte, battery, battery pack, and electrical device provided by this invention include an electrolyte comprising azirene alkylammonium iodate having the structure shown in Formula 1. During charge and discharge, the azirene alkylammonium iodate undergoes an oxidation reaction at the positive electrode to generate an oxide. This oxide diffuses to the negative electrode and reacts with lithium metal to generate lithium ions, activating dead lithium and thus suppressing lithium dendrite formation, improving battery cycle performance. Furthermore, the azirene alkylammonium iodate can generate LiI in the negative electrode interface film (SEI film), reducing the impedance of the negative electrode interface film and thus reducing the risk of lithium plating, further improving battery cycle performance. Simultaneously, the azirene in the azirene alkylammonium iodate, as a bowl-shaped polycyclic aromatic hydrocarbon, has a large dipole moment and strong interaction with elemental iodine or iodide ions, which can suppress the shuttle movement of iodide ions in the electrolyte, reducing cell self-discharge and thus improving battery cycle performance. Therefore, the electrolyte of this invention can suppress lithium plating and self-discharge problems in batteries, improving battery cycle life and other performance characteristics. Attached Figure Description

[0025] Figure 1 The mass spectrometry characterization of azirene butylammonium iodate is shown.

[0026] Figure 2 The graph shows the self-discharge test results of the batteries in Example 1 and Comparative Example 1.

[0027] Figure 3 The graph shows the cycle performance test results of the batteries in Example 1 and Comparative Example 1. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] This invention provides an electrolyte comprising azirconene alkylammonium iodate (first additive), wherein the azirconene alkylammonium iodate comprises a compound having the structure shown in Formula 1:

[0030]

[0031] In Formula 1, R is selected from H, halogen, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 fluoroalkyl, and R1 is selected from substituted or unsubstituted C1 to C10 alkyl.

[0032] In this embodiment of the invention, halogen may specifically include fluorine.

[0033] In this embodiment of the invention, substituted or unsubstituted C1 to C10 alkyl groups (such as R or R1 above) refer to alkyl chains with 1 to 10 carbon atoms that have substituents or are unsubstituted, or cycloalkyl chains with 3 to 10 carbon atoms that have substituents or are unsubstituted; wherein, the alkyl chain can be a straight-chain alkyl group without branches or an isomeric alkyl group with branches; exemplaryly, the number of carbon atoms of C1 to C10 alkyl groups can be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0034] In this embodiment of the invention, the type and position of the substituent are not limited, and can be selected according to actual needs.

[0035] For example, R is selected from methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), butyl (-CH2CH2CH2CH3, -CH2CH(CH3)2, -C(CH3)3) (i.e. tert-butyl (tBu)), etc.

[0036] For example, R1 is selected from methyl, ethyl, propyl, isobutyl, etc., but is not limited thereto.

[0037] According to the above-described solution provided by the present invention, when this electrolyte is applied to a battery, the battery exhibits excellent cycle performance. The reasons for this are twofold: Firstly, the iodine element in azirene alkylammonium iodate has strong oxidizing properties. During battery charging and discharging, azirene alkylammonium iodate can undergo an oxidation reaction at the positive electrode to generate oxides. These oxides diffuse to the negative electrode and react with lithium metal to generate lithium ions, activating dead lithium and thus suppressing lithium dendrite formation, thereby improving the battery's cycle performance. Furthermore, azirene alkylammonium iodate can generate LiI in the negative electrode interface film, reducing the impedance of the negative electrode interface film and thus reducing the risk of lithium plating, further improving the battery's cycle performance. Secondly, azirene in azirene alkylammonium iodate, as a bowl-shaped polycyclic aromatic hydrocarbon, has a large dipole moment and strong interaction with elemental iodine or iodide ions. This can suppress the shuttle movement of iodide ions in the electrolyte, reducing cell self-discharge and thus improving the battery's cycle performance.

[0038] In this embodiment of the invention, azirconene alkylammonium iodate can be obtained by conventional methods in the art, such as commercial purchase or self-preparation by conventional methods for preparing these compounds. In specific implementation, when azirconene alkylammonium iodate is prepared by conventional methods in the art, the structure of the obtained product can be analyzed by conventional analytical means such as mass spectrometry to confirm that azirconene alkylammonium iodate has been successfully prepared.

[0039] The present invention does not limit the preparation method of azirconene alkylammonium iodate. Exemplarily, azirconene alkylammonium iodate can be prepared by a preparation method including the following steps:

[0040] 2,6-Dibromoaniline and the first compound were reacted in the presence of tetra(triphenylphosphine)palladium(O) and potassium carbonate to give the second compound. The second compound was then reacted in the presence of hydrogen chloride, 1,4-dioxane or dioxane to give the third compound. The third compound was then reacted with the fourth compound in the presence of diisopropylethylamine to give the fifth compound. The fifth compound was then reacted in the presence of 2,3-dichloro-5,6-dicyanobenzoquinone to give the sixth compound. The sixth compound was then reacted in the presence of palladium acetate and 1-butylimidazolium tetrafluoroborate to give the seventh compound. The seventh compound was then reacted in the presence of dichloromethyl methyl ether to give the eighth compound. Finally, the eighth compound was reacted with hydrogen iodide to give azirene alkylammonium iodate.

[0041] The first compound includes compounds with the structure shown in Formula 2:

[0042]

[0043] The second compound includes compounds with the structure shown in Formula 3:

[0044]

[0045] The third compound includes compounds with the structure shown in Formula 4:

[0046]

[0047] The fourth compound includes compounds with the structure shown in Formula 5:

[0048]

[0049] The fifth compound includes compounds with the structure shown in Formula 6:

[0050]

[0051] The sixth compound includes compounds with the structure shown in Formula 7:

[0052]

[0053] The seventh compound includes compounds with the structure shown in Formula 8:

[0054]

[0055] The eighth compound includes compounds with the structure shown in Formula 9:

[0056]

[0057] The ninth compound includes compounds with the structure shown in Formula 10:

[0058]

[0059] For example, the preparation reaction of azirconene methylammonium iodate (Formula 1-1) is as follows:

[0060]

[0061] Among them, "HCl in dioxane" indicates the reaction in the presence of hydrochloric acid (HCl) and dioxane as solvent; "i-Pr2NEt DMSO" indicates the reaction in the presence of diisopropylethylamine (i-Pr2NEt) and dimethyl sulfoxide (DMSO) as solvent; "DDQ" indicates the reaction in the presence of dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); "Pd(OAc)2[HPt-Bu2Me][BF4]DBU DMA" indicates the reaction in the presence of lead acetate (Pd(OAc)2), 1,8-diazobisspirocyclic [5.4.0]undecyl-7-ene (DBU), and [HPt-Bu2Me][BF4] and dimethylacetamide (DMA) as solvent; and "NH2OHHCl HI" indicates the reaction in the presence of hydroxylamine hydrochloride (NH2OHHCl) and hydrogen iodide (HI). Mass spectrometry characterization of azirconene methylammonium iodate was performed, and the mass spectra of azirconene butylammonium iodate are shown below. Figure 1 .like Figure 1 As shown, the molecular weight of the synthesized substance is 818.3 m / z, which is consistent with the molecular weight of azirene butylammonium iodate; indicating that azirene butylammonium iodate was successfully prepared.

[0062] In one specific embodiment, the first additive (a compound having the structure shown in Formula 1) includes one or more of the following: azabinene methylammonium iodate (i.e., R is H, R1 is methyl), azabinene ethylammonium iodate (i.e., R is H, R1 is ethyl), azabinene propylammonium iodate (i.e., R is H, R1 is propyl), and azabinene butylammonium iodate (i.e., R is H, R1 is butyl). When the above compounds are selected as azabinene alkylammonium iodates in this embodiment of the invention, the oxides generated by the oxidation of azabinene alkylammonium iodates at the positive electrode react more readily with lithium metal to generate lithium ions, thus better suppressing lithium dendrite formation. Furthermore, azabinene alkylammonium iodates can better generate LiI in the negative electrode interface film, reducing the impedance of the negative electrode interface film. Simultaneously, the larger dipole moment of azabinene alkylammonium iodates can better suppress the shuttle movement of iodide ions in the electrolyte, reducing the self-discharge of the cell, thereby significantly improving the cycle performance of the battery.

[0063] In one specific embodiment, the mass percentage of azirene alkylammonium iodate in the electrolyte is 0.1% to 5%, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof. When the mass percentage of azirene alkylammonium iodate is within the above range, azirene alkylammonium iodate can oxidize to generate a sufficient amount of oxide at the positive electrode, converting lithium dendrites into lithium ions, and can generate sufficient LiI, reducing the impedance of the negative electrode interface film. Simultaneously, it can avoid excessive iodide ions caused by excessive azirene alkylammonium iodate, which leads to self-discharge of the cell, thereby improving the cycle performance of the battery.

[0064] In one specific embodiment, the electrolyte further includes a second additive, which comprises one or more of vinylene carbonate, fluoroethylene carbonate, methyl methane disulfonate (MMDS), and vinyl sulfate (DTD). The embodiments of the present invention utilize the aforementioned second additive, which is compatible with the first additive, forming a more stable SEI film with lower impedance on the electrode surface. This avoids direct contact between the negative electrode material and the electrolyte, preventing oxidative decomposition of the electrolyte and thus better improving the battery's cycle performance.

[0065] In one specific embodiment, the second additive in the electrolyte has a mass percentage of 1.5% to 5%, for example, a range of 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any two of these.

[0066] In one specific embodiment, the electrolyte further includes an organic solvent, which includes cyclic carbonates and / or linear carbonates. When the above-mentioned organic solvents are selected, the electrolyte exhibits high stability, and components such as lithium salt, azirene alkylammonium iodate, and the second additive can be more fully dissolved, resulting in an electrolyte with high conductivity. Simultaneously, the electrolyte has a suitable viscosity, allowing lithium salt, azirene alkylammonium iodate, and conventional additives to better exert their functions, thus enabling the battery to exhibit higher cycle performance.

[0067] In one specific embodiment, the cyclic carbonate includes ethylene carbonate (EC). EC has a high dielectric constant and is compatible with graphite anodes, which is beneficial for improving battery cycle performance. However, it has a high viscosity and a high melting point, so it is preferred to use it in combination with a linear carbonate with low viscosity.

[0068] In one specific embodiment, the linear carbonate includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The aforementioned linear carbonate has low viscosity, which is beneficial for increasing the lithium-ion transport rate in the electrolyte, thereby improving the battery's cycle performance.

[0069] In one specific embodiment, the electrolyte includes a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.9 mol / L to 1.2 mol / L, for example, 1 mol / L. When the concentration of the lithium salt is within the above range, the lithium salt fully exerts its function in the electrolyte, resulting in high ionic conductivity of the electrolyte, thereby improving the cycle performance and storage performance of the battery.

[0070] In one specific embodiment, the electrolyte includes a lithium salt, which is one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). When the above-mentioned compounds are selected as the lithium salt, the lithium salt can fully exert its function to prepare an electrolyte with high ionic conductivity and high stability, thereby enabling the lithium-ion battery to fully exert its electrochemical performance and improve the battery's cycle life and storage performance.

[0071] This invention provides a battery comprising the electrolyte described above. This battery exhibits low lithium plating and self-discharge rates, and demonstrates excellent cycle performance.

[0072] In one specific embodiment, the battery includes a positive electrode sheet, which includes a positive electrode active material, including lithium manganese iron phosphate and / or ternary positive electrode materials.

[0073] The positive electrode sheet of this invention includes a positive current collector and a positive active material layer disposed on the surface of the positive current collector. The positive active material layer includes a positive active material, a conductive agent, and a binder. The positive current collector generally includes aluminum foil.

[0074] The chemical formula of lithium manganese iron phosphate in this embodiment of the invention is LiMn x Fe y PO4, 0 < x < 1, 0 < y < 1, x and y satisfy LiMn x Fe y PO4 is electrically neutral, and generally x + y = 1. For example, lithium manganese iron phosphate can be selected from LiMn. 0.5 Fe 0.5 PO4, LiMn 0.6 Fe 0.4 PO4, LiMn 0.4 Fe 0.6 PO 4。

[0075] The ternary cathode material in this invention refers to a lithium-ion battery cathode material containing three metallic elements (typically nickel, cobalt, and manganese, or nickel, cobalt, and aluminum). Exemplarily, the ternary cathode material includes a nickel-cobalt-manganese ternary material (its chemical formula is LiNi). x Co y Mn 1-x-y O2) and / or nickel-cobalt-aluminum ternary materials (with the chemical formula LiNi) x Co y Al 1-x-y O2).

[0076] When the positive electrode active material is selected from the above-mentioned positive electrode materials, the discharge specific capacity of the battery can be improved.

[0077] In one specific embodiment, the battery includes a negative electrode sheet, which includes a negative electrode active material, comprising one or more of graphite, mesophase carbon microspheres, and silicon-carbon materials. The negative electrode sheet of this embodiment includes a negative electrode current collector and a negative electrode active material layer disposed on the surface of the current collector. The negative electrode active material layer includes a negative electrode active material, a conductive agent, and a binder. The current collector generally includes copper foil.

[0078] In the embodiments of the present invention, the conductive agent and binder in the positive electrode active material layer and the negative electrode active material layer can be conventional materials in the art.

[0079] The lithium-ion battery of this invention also includes a separator. The separator is a separator known in the art that can be used in batteries and is stable to the electrolyte used. It may include one or more of polyolefins, aromatic polyamides, polytetrafluoroethylene, and polyethersulfone, and may be configured as needed.

[0080] This invention also provides a battery pack including the battery described above. This battery pack has advantages corresponding to the electrolyte described above, which will not be elaborated further.

[0081] Generally, a battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0082] This invention also provides an electrical device, including the battery or battery pack described above. This electrical device has advantages corresponding to the electrolyte described above, which will not be elaborated further.

[0083] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations.

[0084] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0085] The present invention will be further described below through specific embodiments and comparative examples. Unless otherwise specified, the reagents, materials and instruments used below are all conventional reagents, materials and instruments, all of which are commercially available, and the reagents and materials involved can also be synthesized by conventional synthetic methods.

[0086] Example 1

[0087] The battery preparation method of this embodiment includes the following steps:

[0088] 1. Electrolyte preparation: Prepare the electrolyte in a glove box filled with 99.999% pure argon gas. The moisture content in the glove box should be controlled at ≤0.1ppm, and the temperature should be controlled at room temperature. Mix ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) in a mass ratio of EC:DMC:DEC:EMC = 16:11:6:15. Then add azirene methyl ammonium iodate, vinylene carbonate (VC), and fluoroethylene carbonate (FEC). Sonicate for 30 minutes until homogeneous. After mixing, add lithium hexafluorophosphate (LiPF6) until the molar concentration of LiPF6 is 1 mol / L. Sonicate to mix evenly to obtain the electrolyte.

[0089] The electrolyte contains 0.5% by mass of azirene methylammonium iodate, 2.2% by mass of vinylene carbonate, and 1.3% by mass of fluoroethylene carbonate.

[0090] 2. LiFePO4 cathode material, conductive agent SuperP (conductive carbon black), conductive agent CNT (carbon nanotubes), and binder PVDF (polyvinylidene fluoride) were mixed evenly at a mass ratio of 96.3:2:0.5:1.2. The mixture was then vacuum stirred until it had uniform fluidity. The slurry was then evenly coated (coating thickness of 50μm) on both sides of an aluminum foil. The foil was then dried at 85℃, cold-pressed, trimmed, cut into sheets, slit, and vacuum-dried at 85℃ for 12 hours. After welding the tabs, an areal density of 33mg / cm³ was obtained. 2 Preparation of the positive electrode and negative electrode: Graphite negative electrode material, conductive agent SuperP (conductive carbon black), binder SBR (polyvinylidene fluoride), and thickener CMC are mixed evenly at a mass ratio of 96.3:2:0.5:1.2. The mixture is then vacuum-stirred until uniformly fluid. This slurry is then evenly coated (45 μm thick) onto both sides of an aluminum foil. The foil is subsequently dried at 85°C, cold-pressed, trimmed, cut, slit, and vacuum-dried at 90°C for 12 hours. After welding the tabs, an area density of 20 mg / cm³ is obtained. 2 The negative electrode sheet.

[0091] 4. The positive electrode, separator, and negative electrode are wound to form the battery cell. In an argon glove box with water and oxygen content both less than 5 ppm, 21 g of electrolyte is injected into a 7 Ah square aluminum-cased lithium battery. The cell is then aged at 25°C dew point for 3 days, followed by formation. After formation, a second electrolyte injection of 3.5 g of experimental electrolyte is performed, followed by high-temperature immersion for 2 days. Finally, capacity testing is conducted to obtain the battery.

[0092] Example 2

[0093] The difference between this embodiment and Embodiment 1 is that azirconene methylammonium iodate is replaced with azirconene ethylammonium iodate.

[0094] Example 3

[0095] The difference between this embodiment and Embodiment 1 is that azirconyl methylammonium iodate is replaced with azirconylallylammonium iodate.

[0096] Example 4

[0097] The difference between this embodiment and Embodiment 1 is that azirconene methylammonium iodate is replaced with azirconene butylammonium iodate.

[0098] Example 5

[0099] The difference between this embodiment and Embodiment 1 is that the mass percentage of azirene methylammonium iodate is 1%.

[0100] Example 6

[0101] The difference between this embodiment and Embodiment 1 is that the mass percentage of azirconene methylammonium iodate is 2%.

[0102] Example 7

[0103] The difference between this embodiment and Example 1 is that the mass percentage of azirene methylammonium iodate is 3%.

[0104] Example 8

[0105] The difference between this embodiment and Embodiment 1 is that the mass percentage of azirene methylammonium iodate is 5%.

[0106] Example 9

[0107] The difference between this embodiment and Embodiment 1 is that the electrolyte does not include VC and FEC.

[0108] Example 10

[0109] The difference between this embodiment and Embodiment 1 is that the mass percentage of VC is 3% and the mass percentage of FEC is 1.5%.

[0110] Example 11

[0111] The difference between this embodiment and Embodiment 1 is that the mass percentage of VC is 5% and the mass percentage of FEC is 1.5%.

[0112] Example 12

[0113] The difference between this embodiment and Embodiment 1 is that the mass percentage of VC is 3.5%.

[0114] Example 13

[0115] The difference between this embodiment and Embodiment 1 is that the mass percentage of VC is 1% and the mass percentage of FEC is 1.5%.

[0116] Example 14

[0117] The difference between this embodiment and Embodiment 1 is that the mass percentage of VC is 8% and the mass percentage of FEC is 1.5%.

[0118] Comparative Example 1

[0119] The difference between this comparative example and Example 1 is that no azirconene methylammonium iodate is added to the electrolyte, the mass percentage of VC is 2.6%, and the mass percentage of FEC is 1.4%.

[0120] Comparative Example 2

[0121] The difference between this comparative example and Example 1 is that azirconene methylammonium iodate, VC and FEC are not added to the electrolyte.

[0122] Table 1

[0123]

[0124] Test case

[0125] Self-discharge test: After the cell is sized to 25% SOC, the open circuit voltage (OCV) of the cell at this time is tested and recorded as V0; the cell is stored at 25℃ for different periods of time, and the OCV of the cell is tested after 7 days and recorded as V7; V7-V0 are recorded in Table 2 and are defined as the K value of self-discharge.

[0126] Room temperature cycle performance test: 1) Capacity calibration: Charging: At room temperature (25±3℃), charge the battery to 3.8V with a constant current and constant voltage of 0.5C, cut off at 0.02C, and let it rest for 30 minutes; Discharging: At room temperature (25±3℃), discharge the battery to 2.0V with a constant current of 0.5C, and let it rest for 30 minutes. Repeat this process 3 times. Record the discharge capacity of the 3rd discharge as the battery's nominal discharge capacity C0. 2) Let it rest for 10 hours, ensuring the battery temperature is 25℃. 3) Charge the battery to 3.8V with a constant current and constant voltage of 1C0. 4) Let it rest for 30 minutes. 5) Discharge the battery to 2.0V with a constant current of 1C0. 6) Cycle steps 2)-5) 500 times, and record the discharge capacity C of the 500th cycle. 500 , using C 500 / C0 calculates the cycle capacity retention rate, disassembles the cell after cycling, examines its negative electrode interface, and verifies the lithium plating on the negative electrode.

[0127] The batteries of Example 1 and Comparative Example 1 were subjected to self-discharge tests. The self-discharge test results are shown in [Figure 1]. Figure 2 ,like Figure 2 As shown, the self-discharge of the batteries in Example 1 and Comparative Example 1 is the same, indicating that azirene alkylammonium iodate has no significant effect on the self-discharge of the batteries.

[0128] The batteries of Example 1 and Comparative Example 1 were subjected to cycle performance tests, and the test results are shown in [Figure 1]. Figure 3 ,like Figure 3As shown, the cycle capacity retention rate of the battery in Example 1 is significantly higher than that of the battery in Comparative Example 1. After 500 cycles, the capacity retention rate of Example 1 is about 3% higher than that of Comparative Example 1.

[0129] Table 2

[0130] Example Self-discharge k-value / mV Capacity retention rate after 500 cycles / % Lithium plating degree Example 1 17.2 99.3 Lithium-free Example 2 16.8 99.5 Lithium-free Example 3 16.9 99.3 Lithium-free Example 4 17.0 99 Lithium-free Example 5 17.5 99.7 Lithium-free Example 6 16.3 98.8 Lithium-free Example 7 16.5 97.4 Lithium-free Example 8 22.2 98.1 Lithium-free Example 9 18 96 Lithium plating at the edge Example 10 17.3 99.5 Lithium-free Example 11 16.5 98.8 Lithium-free Example 12 16.7 98.6 Lithium-free Example 13 17.7 99.2 Lithium-free Example 14 18.2 97 Lithium plating at the edge Comparative Example 1 19.8 94.3 Large-area severe lithium plating Comparative Example 2 20.2 88.2 Large-area severe lithium plating

[0131] As can be seen from Table 2, compared with Comparative Example 1 and Comparative Example 2, in Examples 1 to 14, by introducing azirene alkylammonium iodate with the structure shown in Formula 1 into the electrolyte, it is possible to simultaneously suppress battery self-discharge and lithium plating problems, and improve battery cycle life and other performance.

[0132] Further, as can be seen from Examples 1 and 5 to 8, Examples 1 and 5 to 7, by further controlling the mass percentage of azirene alkylammonium iodate in the electrolyte within the range of 0.1% to 5%, help to further reduce the battery self-discharge K value, suppress battery self-discharge, and at the same time suppress the battery lithium plating problem, thereby further improving the battery's cycle life and other performance.

[0133] As can be seen further from Examples 1 and 9, compared with Example 9, Example 1, by further introducing a second additive into the electrolyte, can more significantly reduce the battery self-discharge K value, further suppress battery self-discharge, and maintain the battery's high cycle life and other performance.

[0134] Therefore, it can be seen that the addition of iodine salt (i.e., azirene alkylammonium iodate) to the electrolyte in this embodiment of the invention has little impact on the self-discharge of the battery, can maintain a low self-discharge K value of the battery, and suppress battery self-discharge. At the same time, the addition of azirene alkylammonium iodate to the electrolyte can effectively suppress lithium plating at the negative electrode and improve the battery's cycle life and other performance. In particular, when a second additive such as VC is introduced into the electrolyte at the same time, azirene alkylammonium iodate has high adaptability to the second additive such as VC. The two work synergistically to further address the problems of suppressing battery self-discharge and lithium plating, and improve the battery's cycle life and other performance.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte, characterized in that, This includes azirconene alkylammonium iodates, which comprise compounds having the structure shown in Formula 1: In Formula 1, R is selected from H, halogen, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 fluoroalkyl, and R1 is selected from substituted or unsubstituted C1 to C10 alkyl.

2. The electrolyte according to claim 1, characterized in that, The compounds having the structure shown in Formula 1 include one or more of the following: azirene methylammonium iodate, azirene ethylammonium iodate, azirene propylammonium iodate, and azirene butylammonium iodate.

3. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte contains 0.1% to 5% by mass of the azirconene alkylammonium iodate.

4. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte also includes a second additive, which includes one or more of vinylene carbonate, fluoroethylene carbonate, methane disulfonate (MMDS), and vinyl sulfate (DTD).

5. The electrolyte according to claim 4, characterized in that, In the electrolyte, the mass percentage of the second additive is 1.5% to 5%.

6. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte further includes an organic solvent, which includes cyclic carbonates and / or linear carbonates; The cyclic carbonates include ethylene carbonate; And / or, the linear carbonate includes one or more of dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

7. The electrolyte according to claim 1, characterized in that, The electrolyte includes a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.9 mol / L to 1.2 mol / L.

8. The electrolyte according to claim 1 or 7, characterized in that, The electrolyte includes a lithium salt, which includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

9. A battery, characterized in that, Includes the electrolyte according to any one of claims 1-8.

10. The battery according to claim 9, characterized in that, The battery includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes lithium manganese iron phosphate and / or ternary positive electrode materials.

11. The battery according to claim 9 or 10, characterized in that, The battery includes a negative electrode sheet, which includes a negative electrode active material, and the negative electrode active material includes one or more of graphite, mesophase carbon microspheres, and silicon-carbon materials.

12. A battery pack, characterized in that, Includes the battery as described in any one of claims 9-11.

13. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 9-11 or the battery pack as described in claim 12.

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