Wide-temperature-range nonaqueous electrolyte, lithium ion battery, battery module, battery pack, power consuming device

Abstract

This invention relates to the field of power battery technology, and in particular to a wide-temperature-range non-aqueous electrolyte, a lithium-ion battery, a battery module, a battery pack, and an electrical device. The non-aqueous electrolyte comprises lithium salts, solvents, and functional additives, wherein the functional additives include ammonium nitrate compounds represented by Formula I and phosphoramide compounds represented by Formula II. Both types of additives contain nitrogen (N), and they can mutually promote decomposition, jointly forming a dense, uniform, and thermally stable interface layer. This layer exhibits excellent ion conductivity at low temperatures and is not easily decomposed or broken at high temperatures.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and in particular to a wide-temperature-range non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and electrical device. Background Technology

[0002] The application scenarios for 3C electronic products and wearable electronic devices are constantly expanding with their development, and their use in extreme environments such as low and high temperatures is becoming increasingly frequent, posing a challenge to the application of lithium-ion batteries. Currently, lithium-ion batteries in 3C electronic products and wearable electronic devices on the market mainly use high-voltage lithium cobalt oxide as the positive electrode. At high temperatures, the side reactions between the electrolyte and the positive electrode surface are aggravated, and cobalt dissolution and lattice oxygen evolution are more likely to occur, which is an irreversible damage to the battery and poses a great risk of combustion and explosion. At low temperatures, the electrolyte viscosity increases, the ionic conductivity decreases, and the desolvation of lithium ions becomes more difficult. The transport of lithium ions in the interface film and electrode materials becomes slower, which greatly reduces the usable capacity of lithium-ion batteries and significantly reduces actual battery life.

[0003] Patent CN117728034A uses a large amount of lithium salt additives and carboxylic acid ester solvents to improve the low-temperature performance of LCO lithium-ion batteries to some extent. However, the use of multiple lithium salts significantly increases the manufacturing cost of the battery, and the low boiling point of carboxylic acid ester solvents can lead to excessive electrolyte decomposition at high temperatures, thus degrading the battery's high-temperature stability and safety. Another patent, CN117810553A, uses a combination strategy of lithium salt additives and nitrile solvents, which to some extent balances the high and low temperature performance of LCO batteries. However, this approach also has certain limitations: nitrile solvents are expensive, which is not conducive to large-scale mass production; and nitrile solvents have poor compatibility with graphite and silicon-carbon anodes, and are prone to side reactions on the electrode surface, generating an unstable interface layer, which ultimately leads to a decrease in reversible capacity and a shortened cycle life. While improving high and low temperature performance, some core electrochemical performance is sacrificed.

[0004] Based on the above, it is essential to design a non-aqueous electrolyte that balances the high and low temperature performance of LCO cells and is economical and feasible. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a wide-temperature-range non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and power device that effectively improves the low-temperature and high-temperature / high-pressure performance of LCO lithium-ion batteries using only two functional additives, while also taking into account other performance aspects. Specifically, ammonium nitrate compounds can form a dense inorganic layer on the positive and negative electrode surfaces, effectively reducing internal resistance and improving low-temperature performance; phosphoramide compounds can form a robust polymer layer on the electrode surface, and amino groups can eliminate free acids in the electrolyte and complex transition metal ions. P and N elements also have certain flame-retardant effects, improving high-temperature / high-pressure performance. These two elements mutually promote decomposition and synergistically improve the high and low temperature performance of the LCO battery cell.

[0006] To achieve the above and other related objectives, a first aspect of the present invention provides a non-aqueous electrolyte comprising a lithium salt, a solvent, and a functional additive, wherein the functional additive comprises an ammonium nitrate compound represented by Formula I and a phosphoramide compound represented by Formula II.

[0007] ;

[0008] Formula I Formula II

[0009] In Formula I, R1 to R5 are each independently selected from hydrogen, halogen, substituted or unsubstituted straight-chain or branched C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy.

[0010] A second aspect of the present invention provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte of the first aspect of the present invention.

[0011] A third aspect of the present invention provides a battery module comprising the lithium-ion battery described in the second aspect of the present invention.

[0012] A fourth aspect of the present invention provides a battery pack including the battery module described in the third aspect of the present invention.

[0013] A fifth aspect of the present invention provides an electrical device comprising the lithium-ion battery described in the second aspect of the present invention, wherein the lithium-ion battery serves as a power source for the electrical device, and the electrical device includes mobile devices, electric vehicles, power tools, electric trains, satellites, ships, and energy storage systems.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] The functional additive proposed in this invention consists of two types of compounds: ammonium nitrate salts represented by Formula I and phosphoramide compounds represented by Formula II. Among them, the ammonium nitrate salts represented by Formula I possess a dual mechanism of action: their dissociation products (such as Li3N, Li...) x NO y Nitrogen-containing inorganic materials can preferentially deposit on the surfaces of both positive and negative electrodes, significantly reducing the internal resistance of the battery cell. Simultaneously, the large-size cationic structure promotes the dissociation process, while the introduction of benzene substituents provides overcharge protection. The phosphoramide compounds shown in Formula II achieve performance optimization by constructing a stable polymer interface film at the positive electrode. Their amino groups can specifically capture free acids and transition metal ions in the electrolyte, reducing adverse factors. Furthermore, the PN synergistic flame-retardant system further enhances the safety of the battery cell. The common N element in both types of additives leads to a synergistic decomposition effect, forming a composite interface film with density, uniformity, and thermal stability. This structure can simultaneously resist low-temperature ion conduction blockage and high-temperature thermal runaway risks, achieving a significant improvement in the wide-temperature-range performance of lithium-ion batteries. Detailed Implementation

[0016] The following describes in detail the embodiments of the wide-temperature-range non-aqueous electrolyte, lithium-ion battery, battery module, battery pack, and power device provided by the present invention.

[0017] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated 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.

[0018] Through extensive research and exploration, the inventors of this invention provide a wide-temperature-range non-aqueous electrolyte. The functional additives consist of two types of compounds: ammonium nitrate salts represented by Formula I and phosphoramide compounds represented by Formula II. The ammonium nitrate salts represented by Formula I possess a dual mechanism of action: their dissociation products (such as Li3N, Li...) x NO y Nitrogen-containing inorganic materials can preferentially deposit on the surfaces of both positive and negative electrodes, significantly reducing the internal resistance of the battery cell. Simultaneously, the large-size cationic structure promotes the dissociation process, while the introduction of benzene substituents provides overcharge protection. The phosphoramide compounds shown in Formula II achieve performance optimization by constructing a stable polymer interface film at the positive electrode. Their amino groups can specifically capture free acids and transition metal ions in the electrolyte, reducing adverse factors. Furthermore, the PN synergistic flame-retardant system further enhances the safety of the battery cell. The common N element in both types of additives leads to a synergistic decomposition effect, forming a composite interface film with density, uniformity, and thermal stability. This structure can simultaneously resist low-temperature ion conduction blockage and high-temperature thermal runaway risks, achieving a significant improvement in the wide-temperature-range performance of lithium-ion batteries. Based on this, this application was completed.

[0019] Wide-temperature-range non-aqueous electrolyte

[0020] This invention provides a wide-temperature-range non-aqueous electrolyte, which includes a lithium salt, a solvent, and functional additives, wherein the functional additives include ammonium nitrate compounds represented by Formula I and phosphoramide compounds represented by Formula II.

[0021] ;

[0022] Formula I Formula II

[0023] In Formula I, R1 to R5 are each independently selected from hydrogen, halogen, substituted or unsubstituted straight-chain or branched C1-C6 alkyl, or substituted or unsubstituted C1-C6 alkoxy. Optionally, R1 to R5 are each independently selected from hydrogen, halogen, substituted or unsubstituted straight-chain or branched C1-C4 alkyl, or substituted or unsubstituted C1-C4 alkoxy. Halogens include, for example, fluorine, chlorine, and bromine. Alkyl groups include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, and sec-butyl. Alkoxy groups include, for example, methoxy and ethoxy. Substituents include, for example, deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0024] Further optionally, in Formula I, R1 to R5 are each independently selected from hydrogen, fluorine, methyl, ethyl, substituted ethyl, trifluoromethyl, monofluoromethyl, and methoxy. The substituents include, for example, deuterium, hydroxyl, amino, mercapto, halogen, cyano, nitro, carbonyl, ester, oxo, imide, phosphine oxide, trifluoromethyl, trifluoromethoxy, C1-C3 alkyl, C1-C3 alkoxy, and any combination thereof.

[0025] Alternatively, in Formula I, R1 to R5 are each independently selected from hydrogen, fluorine, methyl, trifluoromethyl, and methoxy.

[0026] In some embodiments of the present invention, the ammonium nitrate compounds represented by Formula I are selected from one or more of the following structures:

[0027] ;

[0028] Compound 1 Compound 2

[0029] ;

[0030] Compound 3 Compound 4

[0031]

[0032] Compound 5. Compound 6.

[0033] In some embodiments of the present invention, the total mass of the ammonium nitrate compound represented by Formula I and the phosphoramide compound represented by Formula II accounts for 2% to 4% of the electrolyte mass, or any value between them or any two values, and may be selected as 2% to 3% or 3% to 4%. If the additive percentage is too low (<2wt%), the performance of the lithium-ion battery cannot be effectively improved; if the additive percentage is too high (>4wt%), the electrolyte viscosity will increase, and a large number of lithium ions will participate in the decomposition reaction, resulting in more decomposition products accumulating in the interface layer, leading to a decrease in initial efficiency and an increase in internal resistance.

[0034] In some embodiments of the present invention, in order to better leverage the synergistic effect of the two additives and achieve both high and low temperature performance, the mass ratio of the ammonium nitrate compound shown in Formula I to the phosphoramide compound shown in Formula II is 1:(0.5~2) or any value between them or any range between any two values, and can be selected as 1:(0.5~1), 1:(1~1.5), or 1:(1.5~2). If the proportion of the ammonium nitrate compound shown in Formula I is too high, it will be detrimental to improving high-temperature performance; if the proportion of the phosphoramide compound shown in Formula II is too high, it will be detrimental to reducing the cell internal resistance and improving low-temperature performance.

[0035] In some embodiments of the present invention, the lithium salt is selected from one or more combinations of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluorosilicate (LiSiF6), lithium aluminum chloride (LiAlCl4), lithium bis(oxalatoborate) (LiBOB), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium trifluoromethanesulfonate (LiOTF), and lithium bis(trifluoromethanesulfonate)imide (LiTFSI). Preferably, the lithium salt is selected from lithium hexafluorophosphate (LiPF6) and / or lithium bis(fluorosulfonyl)imide (LiFSI).

[0036] In some embodiments of the present invention, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5~2 mol / L and any value or range between therewith, preferably 0.5~1 mol / L, 1~1.2 mol / L, or 1.2~2 mol / L. Preferably, the concentration of the lithium salt in the non-aqueous electrolyte is 1~1.2 mol / L. The lithium salt is a lithium salt in the electrolyte. + The amount of lithium salt is the main source of its influence on the energy density, power density, wide electrochemical window, cycle life, and safety performance of lithium batteries. Too much lithium salt will increase the viscosity of the electrolyte, while too little will fail to provide an adequate amount of lithium ions, both of which will lead to a decrease in ionic conductivity.

[0037] In some embodiments of the present invention, the solvent is selected from one or more combinations of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP), propyl propionate (PP), and methyl butyrate (MB). Preferably, the solvent is selected from ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC). More preferably, the volume ratio of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) is (2~4):(4~6):(1~3). The volume ratio of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) is 3:5:2.

[0038] Further, the solvent in the non-aqueous electrolyte comprises 68 wt% to 75 wt% by mass, or any value between these values, or any two values ​​thereof, optionally 68 wt% to 70 wt% or 70 wt% to 75 wt%. The electrolyte solvent is mainly composed of a mixture of cyclic carbonate solvents and chain carbonate solvents in a certain proportion. Cyclic carbonate solvents have a higher dielectric constant, which is beneficial for lithium ion dissociation, but a large quantity will increase the viscosity of the electrolyte and reduce the ionic conductivity. Chain carbonate solvents have a lower viscosity and better electrochemical stability, but a large quantity will lead to poorer lithium ion dissociation.

[0039] Lithium-ion batteries

[0040] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and the non-aqueous electrolyte described in the first aspect of the present invention.

[0041] The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The positive electrode active material layer includes a positive electrode active material, and may further include a conductive agent and a binder. The positive electrode active material may be selected from one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, and lithium iron phosphate. Lithium cobalt oxide is preferred. Those skilled in the art can select conductive agents and binders suitable for lithium-ion batteries. The conductive agent may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The adhesive may include, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0042] In some embodiments, the positive electrode can be prepared by dispersing the above-mentioned components for preparing the positive electrode, such as the positive electrode material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode after drying, cold pressing and other processes.

[0043] The negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal 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 negative electrode active material layer includes a negative electrode active material, and may further include a plasticizer, a conductive agent, and a binder. The negative electrode active material can be selected from one or more of silicon-carbon, silicon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal; preferably, the negative electrode active material can be selected from artificial graphite. Those skilled in the art can select plasticizers, conductive agents, and binders suitable for lithium-ion batteries. The conductive agent can be selected, for example, from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. 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), carboxymethyl chitosan (CMCS), and sodium carboxymethyl cellulose (CMC-Na).

[0044] In some embodiments, the negative electrode can be prepared by dispersing the components used to prepare the negative electrode, such as the negative electrode material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode after drying, cold pressing and other processes.

[0045] The lithium-ion battery provided in the second aspect of the present invention can be prepared using methods known in the art. For example, a positive electrode, a separator, and a negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes, and then the layers are stacked to obtain a bare cell; the bare cell is placed in an outer packaging shell, dried, and then injected with electrolyte, and after vacuum sealing, settling, formation, shaping, and other processes, a lithium-ion battery is obtained.

[0046] Battery Module

[0047] A third aspect of the present invention provides a battery module comprising any one or more lithium-ion batteries described in the second aspect of the present invention. The number of lithium-ion batteries in the battery module can be adjusted according to the application and capacity of the battery module.

[0048] Battery Pack

[0049] A fourth aspect of the present invention provides a battery pack comprising any one or more battery modules described in the third aspect of the present invention. That is, the battery pack comprises any one or more lithium-ion batteries described in the second aspect of the present invention.

[0050] The number of battery modules in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0051] Electrical appliances

[0052] A fifth aspect of the present invention provides an electrical device comprising any one or more lithium-ion batteries described in the second aspect of the present invention. The lithium-ion batteries can be used as a power source for the electrical device. Preferably, the electrical device may be, 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.

[0053] The beneficial effects of the present invention will be further illustrated below with reference to the embodiments.

[0054] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described in detail below with reference to embodiments. However, it should be understood that the embodiments of this invention are merely for illustrative purposes and not for limiting the invention, and the embodiments are not limited to those given in the specification. Unless otherwise specified, specific experimental or operational conditions in the embodiments were prepared under conventional conditions or according to the conditions recommended by the material supplier.

[0055] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0056] In the following embodiments, unless otherwise specified, all the raw materials of the present invention are commercially available or prepared according to conventional methods in the art.

[0057] The lithium-ion battery used in the embodiments of this invention uses lithium cobalt oxide as the positive electrode material and artificial graphite as the negative electrode. The electrolyte injection amount for each battery is 4g. The preparation process of the lithium-ion batteries in Examples 1-9 and Comparative Examples 1-10 is as follows:

[0058] Electrolyte was prepared in a dry room (dew point below -40℃). Ethyl methyl carbonate (EMC), ethylene carbonate (EC), and diethyl carbonate (DEC) were mixed in a volume ratio of 5:3:2 as an organic solvent. LiPF6 with a lithium salt molar concentration of 1 mol / L was added to this organic solvent (75 wt% of the non-aqueous electrolyte), followed by functional additives in different proportions as shown in Table 1. After thorough mixing, the electrolyte was injected into a pouch cell. After standing, formation, and capacity testing, a lithium-ion battery was obtained.

[0059] Table 1

[0060]

[0061] The batteries obtained in Examples 1-9 and Comparative Examples 1-10 were subjected to the following experiments, and the test results are shown in Tables 2 and 3.

[0062] (1) Room temperature storage performance test: After formation and capacity testing, the batteries obtained in Examples 1-9 and Comparative Examples 1-10 were charged at 25°C with a constant current and constant voltage of 1C to a voltage of 4.45V and a current of 0.05C. After being stored for 10 minutes, the voltage V1 was recorded. After the fully charged battery was stored at 25°C for 72 hours, the voltage V2 was measured again. Voltage drop calculation formula: ΔV=V1-V2.

[0063] (2) High-temperature cycle performance test: After formation and capacity testing, the batteries obtained in Examples 1-9 and Comparative Examples 1-10 were charged at 25°C with a constant current and constant voltage of 1C to a voltage of 4.45V and a current of 0.05C. After resting for 10 minutes, they were discharged at a constant current of 1C to a voltage of 2.75V. This constitutes one charge-discharge cycle. After formation and capacity testing, the obtained batteries were subjected to charge-discharge cycles at 45°C.

[0064] (3) High-temperature storage performance test: After the batteries obtained in Examples 1 to 9 and Comparative Examples 1 to 10 were formed and capacity tested, they were charged at 25°C with 1C constant current and constant voltage to a voltage of 4.45V and a current of 0.05C. The 1C capacity Q and battery thickness H were recorded respectively. The fully charged batteries were stored at 60°C for 30 days. The 1C discharge capacity Q1 and battery thickness H1 were recorded at 25°C. The batteries were charged at 1C constant current and constant voltage to a voltage of 4.45V and a current of 0.05C and then discharged at 1C constant current to 2.75V. The 1C discharge capacity Q2 was recorded. The capacity retention rate, recovery rate and battery expansion rate of the batteries after storage were calculated.

[0065] The calculation formulas are as follows:

[0066] Capacity retention rate = Q1 / Q × 100%; Capacity recovery rate = Q2 / Q × 100%; Battery expansion rate = (H1-H) / H × 100%.

[0067] (4) Low-temperature discharge test: After the batteries obtained in Examples 1 to 9 and Comparative Examples 1 to 10 were formed and capacity tested, they were charged at 25°C with 1C constant current and constant voltage to a voltage of 4.45V and a current of 0.05C, and then discharged at 1C constant current to 2.75V. The 1C discharge capacity Q was recorded. The fully charged batteries were discharged at -30°C, -20°C, -10°C and 0°C with 1C constant current to 2.75V. The 1C discharge capacity Q1 was recorded. The low-temperature discharge retention rate of the batteries was calculated.

[0068] The calculation formula is as follows:

[0069] Capacity retention rate = Q1 / Q × 100%.

[0070] Table 2

[0071]

[0072] Table 3

[0073]

[0074] As shown in Tables 2 and 3, when the total amount of functional additives is limited to 2%–4% of the electrolyte mass, and the mass ratio of the two additives is maintained within the range of 1:(0.5–2), lithium-ion batteries exhibit lower self-discharge and superior high-temperature cycle performance, high-temperature storage performance, and low-temperature discharge performance. This is mainly due to the reasonable control of the dosage and precise compound ratio of the two additives, which allows for a better synergistic effect between functional groups, forming a composite interface layer with density, high conductivity, and high thermal stability. This structure can simultaneously resist the risks of low-temperature ion conduction blockage and high-temperature thermal runaway, achieving a significant improvement in the wide-temperature-range performance of lithium-ion batteries and effectively avoiding the drawbacks of "sacrificing one aspect for another" in the performance optimization process of comparative batteries.

[0075] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that those skilled in the art can make various improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art based on the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A wide-temperature-range non-aqueous electrolyte, characterized in that, The non-aqueous electrolyte includes lithium salt, solvent and functional additives, wherein the functional additives include ammonium nitrate compounds represented by Formula I and phosphoramide compounds represented by Formula II; Formula I Formula II In Formula I, R1 to R5 are each independently selected from hydrogen, halogen, substituted or unsubstituted straight-chain or branched C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy. The total mass of the ammonium nitrate compounds shown in Formula I and the phosphoramide compounds shown in Formula II accounts for 2% to 4% of the mass of the non-aqueous electrolyte; and the mass ratio of the ammonium nitrate compounds shown in Formula I to the phosphoramide compounds shown in Formula II is 1:(0.5 to 2).

2. The wide-temperature-range non-aqueous electrolyte according to claim 1, characterized in that, In Formula I, R1 to R5 are each independently selected from hydrogen, halogen, substituted or unsubstituted straight-chain or branched C1-C4 alkyl, substituted or unsubstituted C1-C4 alkoxy.

3. The wide-temperature-range non-aqueous electrolyte according to claim 1, characterized in that, In Formula I, R1 to R5 are each independently selected from hydrogen, fluorine, methyl, ethyl, substituted ethyl, trifluoromethyl, monofluoromethyl, and methoxy.

4. The wide-temperature-range non-aqueous electrolyte according to claim 1, characterized in that, The ammonium nitrate compounds represented by Formula I are selected from one or more of the following structures: ； Compound 1 Compound 2 ； Compound 3 Compound 4 Compound 5. Compound 6.

5. The wide-temperature-range non-aqueous electrolyte according to claim 1, characterized in that, It also includes one or more of the following conditions: B1) The lithium salt is selected from one or more combinations of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium aluminum chloride, lithium bis(oxalate-borate), lithium chloride, lithium bromide, lithium iodide, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonate)imide. B2) The concentration of the lithium salt in the non-aqueous electrolyte is 0.5~2 mol / L; B3) The solvent is selected from one or more combinations of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, ethyl propionate, propyl propionate, and methyl butyrate. B4) The solvent in the non-aqueous electrolyte has a mass percentage of 68 wt% to 75 wt%.

6. The wide-temperature-range non-aqueous electrolyte according to claim 5, characterized in that, It also includes one or more of the following conditions: B11) In feature B1), the lithium salt is selected from lithium hexafluorophosphate and / or lithium bisfluorosulfonylimide; B21) In feature B2), the concentration of the lithium salt in the non-aqueous electrolyte is 1~1.2 mol / L; B31) In feature B3), the solvent is selected from ethylene carbonate, methyl ethyl carbonate and diethyl carbonate.

7. A lithium-ion battery, characterized in that, The invention comprises a positive electrode, a negative electrode, a separator membrane spaced between the positive and negative electrodes, and a non-aqueous electrolyte, characterized in that the non-aqueous electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 6.

8. The lithium-ion battery according to claim 7, characterized in that, It also includes one or more of the following conditions: C1) The positive electrode includes a positive electrode active material, which is selected from one or more of lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, and lithium iron phosphate. C2) The negative electrode includes a negative electrode active material, which is selected from one or more of silicon-carbon, silicon-oxygen, natural graphite, artificial graphite, lithium titanate, amorphous carbon, and lithium metal.

9. A battery module, characterized in that, Including the lithium-ion battery according to claim 7 or 8.

10. A battery pack, characterized in that, Includes the battery module according to claim 9.

11. An electrical appliance, characterized in that, Includes the lithium-ion battery according to claim 7 or 8, wherein the lithium-ion battery is used as a power source for the device, and the device includes mobile devices, electric vehicles, power tools, electric trains, satellites, ships, and energy storage systems.

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