Electrolyte, battery and electric device
By adding perfluoroalkylsilane compounds to the electrolyte of lithium metal batteries, the problem of low solubility of lithium nitrate in carbonate solvents is solved, a stable SEI film is formed, lithium dendrite growth is inhibited, and the cycle life and performance of the battery are improved.
Patent Information
- Application Number
- CN202511429864.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-02-10
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of batteries, in particular to an electrolyte, a battery and a power utilization device. BACKGROUND
[0002] Lithium metal is one of the ideal negative materials for batteries due to its high theoretical capacity (3860 mAh / g) and low reduction potential (-3.04 V vs SHE). However, problems such as lithium dendrite formation hinder its commercialization process. Due to the high reactivity of lithium metal to electrolyte components, it is still challenging to control lithium deposition morphology and solid electrolyte interface (SEI) formation. Unstable SEI will lead to side reactions and lithium dendrite growth, which seriously affects the electrochemical performance of the battery. Therefore, building a stable SEI layer is crucial for the long-term performance of lithium metal batteries.
[0003] Inhibiting lithium dendrite growth by electrolyte additives is an effective strategy to improve the performance of lithium metal batteries. Among the numerous additives such as fluoroethylene carbonate (FEC), vinylene carbonate (VC), lithium difluoro(oxalato)borate (LiDFOB), lithium nitrate (LiNO3) is considered to be an effective lithium metal negative electrode additive due to its nitrate functional group which can stabilize the SEI and promote uniform lithium deposition. LiNO3 is commonly used as an additive for ether-based electrolytes, but the high highest occupied molecular orbital energy level (HOMO) of ether-based electrolytes makes it inherently insufficient in oxidation resistance. When the battery voltage exceeds 4.0V, it will undergo severe oxidative decomposition, making it difficult to form a stable and reliable electrode / electrolyte interface, resulting in serious irreversible capacity loss and poor electrochemical stability, and therefore cannot be effectively applied to high-voltage positive electrode material systems. Carbonate-based electrolyte solvents have high dielectric constant, making them have good high-voltage resistance performance, and are widely used in various lithium ion batteries, but the low solubility of LiNO3 in carbonate electrolytes limits its application. SUMMARY
[0004] Embodiments of the present application provide an electrolyte, a battery and a power utilization device, which can improve the technical problem of low solubility of lithium nitrate in carbonate-based organic solvents.
[0005] In a first aspect, embodiments of the present application provide an electrolyte, the electrolyte comprising a lithium salt, a carbonate-based organic solvent, lithium nitrate and an electrolyte additive, the electrolyte additive comprising a perfluoroalkyl silane compound having a structural formula as shown in formula (I): R f -R2-Si(OR1)3 formula (I); In formula (I), R1 and R2 are each independently a derivative of an alkyl group or an aryl group; R f is a perfluoroalkyl chain having a structural formula as shown in formula (II): C n F2n+1 Formula (II); In Formula (II), n is an integer from 4 to 8.
[0006] The electrolyte additive is added to an electrolyte containing a lithium salt, a carbonate organic solvent and lithium nitrate. The perfluoroalkylsilane compound forms a strong interaction with the nitrate (NO3 - ) of lithium nitrate through the strong electronegativity of fluorine atoms, and combines the solvent shielding effect of the hydrophobic perfluoroalkyl chain, while the silane bond in the perfluoroalkylsilane compound resists electrolyte decomposition, significantly improving the solubility of lithium nitrate in carbonate organic solvents while also extending the cycle life of the battery.
[0007] In an embodiment, in Formula (I), R1 and R2 are each independently a derivative of methyl, ethyl or phenyl.
[0008] In an embodiment, the perfluoroalkyl chain is C4F9 or C8F 17 .
[0009] The perfluoroalkylsilane compound described above not only has easy preparation, but also has good performance.
[0010] In an embodiment, in the electrolyte, the mass fraction of the lithium nitrate is 0.1wt% to 1.5wt%.
[0011] Lithium nitrate as an SEI film forming additive can promote the formation of a stable SEI film on the negative electrode surface. Too low a mass fraction of lithium nitrate in the electrolyte can lead to an unstable SEI film, while too high a mass fraction of lithium nitrate can lead to an excessively thick SEI film. Moreover, lithium nitrate itself has poor solubility in carbonate organic solvents, and too high a mass fraction of lithium nitrate can not be completely dissolved, which can cause side reactions (such as gas production) or increase the viscosity of the electrolyte, thereby negatively affecting the performance of the battery.
[0012] In an embodiment, in the electrolyte, the mass fraction of the perfluoroalkylsilane compound is 0.1wt% to 3wt%.
[0013] Too low a mass fraction of the perfluoroalkylsilane compound in the electrolyte can make it difficult to effectively improve the solubility of LiNO3 in carbonate organic solvents, while too high a mass fraction of the perfluoroalkylsilane compound can deteriorate the performance of the electrolyte, leading to an increase in side reactions.
[0014] In an embodiment, in the electrolyte, the mass ratio of the perfluoroalkylsilane compound to the lithium nitrate is (1 to 3): 1.
[0015] By controlling the mass ratio of the perfluoroalkyl silane compound and the lithium nitrate in the electrolyte, the perfluoroalkyl silane compound and the lithium nitrate can be effectively matched, and the solubility of the lithium nitrate in the carbonate organic solvent can be improved.
[0016] In an embodiment, the lithium salt includes at least one of an organic lithium salt and an inorganic lithium salt, the organic lithium salt includes at least one of lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(difluorosulfonyl)imide and lithium bis(trifluoromethylsulfonyl)imide, and the inorganic lithium salt includes at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate and lithium hexafluorophosphate.
[0017] The lithium salt can be effectively dissolved in the carbonate organic solvent.
[0018] In an embodiment, the concentration of the lithium salt in the electrolyte is 0.1 mol / L to 2 mol / L.
[0019] Increasing the concentration of the lithium salt in the electrolyte can improve the conductivity of the electrolyte, but as the concentration of the lithium salt increases, the viscosity of the electrolyte increases, which limits the migration of lithium ions and reduces the conductivity of the electrolyte.
[0020] In an embodiment, the carbonate organic solvent includes at least one of vinyl carbonate, propylene carbonate, diethyl carbonate, fluoro-vinyl carbonate, dimethyl carbonate and ethyl methyl carbonate.
[0021] Vinyl carbonate, propylene carbonate and fluoro-vinyl carbonate, as cyclic carbonates, have high dielectric constant and high ionic conductivity, and can form a good SEI film on the surface of the negative electrode, which not only helps to improve the initial efficiency of the battery, but also prolongs the service life of the battery.
[0022] Diethyl carbonate, dimethyl carbonate and ethyl methyl carbonate, as chain carbonates, have low viscosity, which helps the migration of lithium ions in the electrolyte, thereby improving the charge and discharge rate and cycle performance of the battery; at the same time, low viscosity also helps to improve the performance of the battery in a low temperature environment.
[0023] In an embodiment, the mass fraction of the carbonate organic solvent in the electrolyte is 70wt% to 85wt%.
[0024] As the medium for ion transmission in the electrolyte, controlling the content of the carbonate organic solvent in the electrolyte helps to regulate the electrochemical performance of the electrolyte and enhance the stability of the electrode / electrolyte interface.
[0025] In a third aspect, an embodiment of the present application provides a battery including the above-mentioned electrolyte.
[0026] In an embodiment, the battery is a lithium metal battery, and a negative electrode of the lithium metal battery is a lithium metal negative electrode.
[0027] The lithium metal negative electrode has a high theoretical specific capacity and a low electrochemical potential, thus making the lithium metal battery have a high energy density.
[0028] In a fourth aspect, embodiments of the present application provide a power utilization device comprising the battery described above. DETAILED DESCRIPTION
[0029] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person skilled in the art without creative work fall within the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.
[0030] In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, and "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The words first, second, third, etc. are only used as labels, and do not impose numerical requirements or establish sequences.
[0031] In the present application, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.
[0032] In the present application, "at least one" means one or more, and "multiple" means two or more. "One or more", "at least one of the following (one)", or similar expressions, means any combination of these items, including any combination of single item (one) or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple.
[0033] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be construed as a hard limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single values within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fraction or integer) within the indicated range.
[0034] Some embodiments of the present application provide a power consuming device using a battery as a power source, which can be, but is not limited to, a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. In the power consuming device, the battery can be used as an operating power source or a driving power source.
[0035] Some embodiments of the present application provide a battery, and a power consuming device comprising the battery.
[0036] In some embodiments of the present application, the battery comprises a positive electrode sheet, a negative electrode sheet, and a separator. Specifically, the positive electrode sheet is arranged opposite to the negative electrode sheet, and the separator is arranged between the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from contacting each other and causing a short circuit. It should be noted that the battery can comprise at least one of a battery cell, a battery module, and a battery pack, etc.
[0037] In some embodiments of the present application, the battery is a secondary battery. Here, the secondary battery refers to a battery that can be activated by charging after discharging to continue to be used. As an example, the battery is a lithium ion battery.
[0038] In some embodiments of the present application, the positive electrode sheet comprises a positive electrode active material. Optionally, the positive electrode sheet comprises a positive electrode film layer, and the positive electrode film layer comprises the positive electrode active material. As an example, the positive electrode sheet further comprises a positive electrode current collector, and the positive electrode film layer is arranged on the positive electrode current collector; in another example, the positive electrode sheet is a self-supporting structure, and the positive electrode sheet only comprises the positive electrode film layer without the positive electrode current collector. Further, the positive electrode film layer further comprises a conductive agent and a binder. In the positive electrode sheet, the conductive agent comprises at least one of carbon black, graphite, carbon nanotubes (CNTs), graphene, and carbon fibers, the binder comprises polyvinylidene fluoride (PVDF), the positive electrode current collector comprises aluminum foil, and the positive electrode active material comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium nickel manganese acid, lithium cobalt acid, lithium-rich manganese-based, and lithium manganese acid.
[0039] In some embodiments of the present application, the separator can be selected from one or more of a polyolefin separator, a non-woven fabric separator, a ceramic-coated separator, and a composite separator. As an example, the polyolefin separator includes at least one of a polyethylene (PE) film and a polypropylene (PP) film. The separator can be a dry process separator or a wet process separator, without limitation.
[0040] In some embodiments of the present application, the battery is a lithium metal battery, and the negative electrode of the lithium metal battery is a lithium metal negative electrode.
[0041] The lithium metal battery is a battery with a lithium metal negative electrode as the negative electrode. Optionally, the lithium metal battery is a rechargeable battery. The lithium metal negative electrode has a high theoretical specific capacity and a low electrochemical potential, thereby enabling the lithium metal battery to have a high energy density.
[0042] Some embodiments of the present application provide another electrolyte, and the above-mentioned battery includes the electrolyte.
[0043] When the battery includes a positive electrode sheet, a negative electrode sheet, and a separator, the electrolyte is used to soak the positive electrode sheet, the negative electrode sheet, and the separator. The electrolyte provides an ion channel during the charging and discharging of the battery, enabling the charge transfer between the positive electrode sheet and the negative electrode sheet, thereby completing the storage and release of energy.
[0044] In some embodiments of the present application, the electrolyte includes a lithium salt and an organic solvent. The lithium salt is dissolved in the organic solvent as an electrolyte, and the lithium salt is dissociated into cations and anions in the organic solvent. The organic solvent provides a medium for the movement of ions, thereby realizing ion conduction.
[0045] In some embodiments of the present application, the organic solvent is a carbonate-based organic solvent. The carbonate-based organic solvent has good electrochemical stability, a high dielectric constant, and a high electrical conductivity, which can provide a stable electrolyte environment to support the efficient operation of the battery. Optionally, the carbonate solvent includes at least one of a cyclic carbonate and a chain carbonate. As an example, the cyclic carbonate includes at least one of ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate. The cyclic carbonate has a high dielectric constant and a high ionic conductivity, which can form a good SEI film on the negative electrode surface, not only helping to improve the initial efficiency of the battery, but also prolonging the service life of the battery. As an example, the straight-chain carbonate includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The chain carbonate has a relatively low viscosity, which helps the migration of lithium ions in the electrolyte, thereby improving the charge and discharge rate and the cycle performance of the battery; at the same time, the low viscosity also helps to improve the performance of the battery in a low-temperature environment.
[0046] In some embodiments of this application, the mass fraction of carbonate organic solvents in the electrolyte is 70wt% to 85wt%. Carbonate organic solvents serve as ion transport media in the electrolyte; controlling their content helps regulate the electrochemical performance of the electrolyte and enhances the stability of the electrode / electrolyte interface. As an example, the mass fraction of carbonate organic solvents in the electrolyte is 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt%, 82wt%, 83wt%, 84wt%, or 85wt%.
[0047] In some embodiments of this application, the lithium salt includes at least one of inorganic lithium salts and organic lithium salts. Optionally, the inorganic lithium salt includes at least one of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6). Optionally, the organic lithium salt includes at least one of lithium bis(oxalato)borate (LiBOB), lithium difluorooxalato)borate (LiDFOB), lithium bis(difluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The above lithium salts are effectively soluble in carbonate organic solvents.
[0048] In some embodiments of this application, the concentration of lithium salt in the electrolyte is 0.1 mol / L to 2 mol / L. Increasing the concentration of lithium salt in the electrolyte can improve the conductivity of the electrolyte; however, as the concentration of lithium salt increases, the viscosity of the electrolyte increases, which in turn restricts the migration of lithium ions and reduces the conductivity of the electrolyte. As examples, the concentration of lithium salt in the electrolyte is 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, or 2 mol / L.
[0049] In some embodiments of this application, the electrolyte further includes additives. These additives are primarily used to improve the performance of the electrolyte. Further, the additives include lithium nitrate (LiNO3). Lithium nitrate can promote uniform lithium deposition and inhibit lithium dendrite growth by forming a stable solid electrolyte interphase (SEI) film, thereby improving the cycle stability and coulombic efficiency of the battery (especially lithium metal batteries). Specifically, lithium nitrate undergoes a reduction reaction on the surface of the negative electrode (especially the lithium metal negative electrode) and decomposes to generate Li3N, Li2O, and LiN. x O y Inorganic products, such as lithium nitrate, can form a stable SEI film on the negative electrode surface. However, lithium nitrate has low solubility in carbonate organic solvents, which severely limits its application.
[0050] Embodiments of this application provide an electrolyte comprising a lithium salt, a carbonate organic solvent, lithium nitrate, and an electrolyte additive. The electrolyte additive can coordinate with lithium nitrate and effectively improve the solubility of lithium nitrate (LiNO3) in the carbonate organic solvent. Specifically, the electrolyte additive comprises a perfluoroalkylsilane compound with the structural formula shown in formula (I): R f - R2- Si(OR1)3 formula (Ⅰ); In formula (Ⅰ), R1 and R2 are each independently an alkyl or aryl derivative; R f It is a perfluoroalkyl chain with the structural formula shown in formula (II): C n F 2n+1 Equation (II); In equation (Ⅱ), n is an integer from 4 to 8.
[0051] As an example, n can be 4, 5, 6, 7, or 8.
[0052] The aforementioned perfluoroalkylsilane compounds (PFAS) can enhance the solubility of LiNO3 in carbonate organic solvents through the following synergistic mechanism: First, perfluoroalkylsilane compounds contain perfluoroalkyl chains (R... f The fluorine atom in the perfluoroalkyl chain is highly electronegative, and this fluorine atom can react with the nitrate ion NO3 of lithium nitrate. - The formation of F···O-NO2 dipole interaction weakens Li + -NO3 - Ion pair binding energy.
[0053] Secondly, the perfluoroalkyl chain, as a hydrophobic chain, brings a solvation shielding effect. This means that the hydrophobicity of the perfluoroalkyl chain can reduce the polar repulsion between the additive and carbonate organic solvents, thus promoting the uniform dispersion of lithium nitrate.
[0054] Furthermore, the silane group (Si-R) in perfluoroalkylsilane compounds exhibits good stability, and the silane bond in the silane group can resist electrolyte decomposition, thus extending the cycle life of the battery.
[0055] In summary, when the above-mentioned electrolyte additives are added to electrolytes containing lithium salts, carbonate organic solvents, and lithium nitrate, the perfluoroalkylsilane compounds react with the nitrate ions (NO3) of lithium nitrate due to the strong electronegativity of the fluorine atoms. - They form strong interactions and combine with the solvation shielding effect of hydrophobic perfluoroalkyl chains. At the same time, the silane bonds in the perfluoroalkyl silane compounds resist electrolyte decomposition, significantly improving the solubility of lithium nitrate in carbonate organic solvents and extending the cycle life of the battery.
[0056] When this electrolyte additive is applied to high-energy-density lithium metal batteries, it can stabilize the lithium metal anode interface and inhibit dendrite growth. Experiments show that when 1 wt% of a perfluoroalkylsilane compound is added to the electrolyte, the solubility of LiNO3 in an electrolyte containing carbonate-based organic solvent EC / EMC (v:v=3:7) increases from less than 0.5 wt% to 1.5 wt%.
[0057] In some embodiments of this application, in formula (Ⅰ), R1 and R2 are each independently a derivative of methyl, ethyl or phenyl.
[0058] In some embodiments of this application, the perfluoroalkyl chain is C4F9 or C8F. 17 .
[0059] The aforementioned perfluoroalkylsilane compounds are not only easy to prepare, but also have excellent performance.
[0060] In some embodiments of this application, the mass fraction of lithium nitrate in the electrolyte is 0.1 wt% to 1.5 wt%. Lithium nitrate, as an SEI film-forming additive, can promote the formation of a stable SEI film on the negative electrode surface. Too low a mass fraction of lithium nitrate in the electrolyte may lead to an unstable SEI film, while too high a mass fraction may result in an excessively thick SEI film. Furthermore, lithium nitrate itself has poor solubility in carbonate organic solvents; too high a mass fraction makes it difficult to dissolve completely, and may also cause side reactions (such as gas production) or increase electrolyte viscosity, negatively impacting battery performance. As an example, the mass fraction of lithium nitrate in the electrolyte is any one or a range between any two of 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt%, 0.9 wt%, 1.1 wt%, 1.3 wt%, and 1.5 wt%.
[0061] In some embodiments of this application, the mass fraction of the perfluoroalkylsilane compound in the electrolyte is 0.1 wt% to 3 wt%. Too low a mass fraction of the perfluoroalkylsilane compound in the electrolyte may fail to effectively improve the solubility of LiNO3 in carbonate organic solvents; however, too high a mass fraction may deteriorate the electrolyte performance and exacerbate side reactions. As an example, the mass fraction of the perfluoroalkylsilane compound in the electrolyte is any one or any two of the following: 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, and 3.0 wt%.
[0062] In some embodiments of this application, the mass ratio of perfluoroalkylsilane compound to lithium nitrate in the electrolyte is (1~3):1.
[0063] By controlling the mass ratio of perfluoroalkylsilane compound to lithium nitrate in the electrolyte, the perfluoroalkylsilane compound and lithium nitrate can be effectively combined, thereby improving the solubility of lithium nitrate in carbonate organic solvents. As an example, the mass ratio of perfluoroalkylsilane compound to lithium nitrate in the electrolyte is 1:1, 1.5:1, 2:1, 2.5:1, or 3:1.
[0064] The following description is based on specific embodiments.
[0065] Example 1 This embodiment provides an electrolyte, the preparation process of which is as follows: Weigh LiPF6 in a high-purity argon glove box and dissolve it in EC:EMC (3:7, v / v) at a molar concentration of 1 mol / L. Then weigh 1H,1H,2H,2H-perfluorooctyltriethoxysilane (molecular formula C6H2O) separately. 14 H 13 F 13 O3Si (CAS No. 51851-37-7) and LiNO3 were added and stirred with a magnetic stirrer for 12 hours to obtain the electrolyte. Please refer to Table 1. In the electrolyte, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 were 1wt% and 0.5wt%, respectively, and the mass ratio of the two in the electrolyte was 2:1. The electrolyte was stored in a high-purity argon glove box for later use.
[0066] The structural formula of 1H,1H,2H,2H-perfluorooctyltriethoxysilane is shown below: .
[0067] Example 2 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 2 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 1.6wt% and 0.8wt%, respectively.
[0068] Example 3 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 3 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 2.2wt% and 1.1wt%, respectively.
[0069] Example 4 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 4 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 2.8 wt% and 1.4 wt%, respectively.
[0070] Example 5 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 5 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 0.2wt% and 0.1wt%, respectively.
[0071] Example 6 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 6 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 0.5wt% and 0.5wt%, respectively, and the mass ratio of the two in the electrolyte is 1:1.
[0072] Example 7 This embodiment provides an electrolyte. The preparation process of the electrolyte is described in Example 1. The only difference between Example 7 and Example 1 is that, as shown in Table 1, the mass fractions of 1H,1H,2H,2H-perfluorooctyltriethoxysilane and LiNO3 in the electrolyte are 1.5wt% and 0.5wt%, respectively, and the mass ratio of the two in the electrolyte is 3:1.
[0073] Example 8 This embodiment provides an electrolyte. The preparation process of this electrolyte is described in Example 1. The only difference between Example 8 and Example 1 is that, as shown in Table 1, 1H,1H,2H,2H-perfluorodecyltriethoxysilane (molecular formula C) is used in the electrolyte. 16 H 19 F 17 O3Si (CAS No. 101947-16-4) replaces 1H,1H,2H,2H-perfluorooctyltriethoxysilane.
[0074] The structural formula of 1H,1H,2H,2H-perfluorodecyltriethoxysilane is shown below: .
[0075] Example 9 This embodiment provides an electrolyte. The preparation process of this electrolyte is described in Example 1. The only difference between Example 9 and Example 1 is that, as shown in Table 1, 1H,1H,2H,2H-perfluorohexyltrimethoxysilane (molecular formula C9H7F9O3Si; CAS number 85877-79-8) is used instead of 1H,1H,2H,2H-perfluorooctyltriethoxysilane in the electrolyte.
[0076] The structural formula of 1H,1H,2H,2H-perfluorohexyltrimethoxysilane is shown below: .
[0077] Comparative Example 1 This comparative example provides an electrolyte, the preparation process of which is as follows: Weigh LiPF6 in a high-purity argon glove box and dissolve it in EC:EMC (3:7, v / v) at a molar concentration of 1 mol / L. Stir with a magnetic stirrer for 12 h and store in a high-purity argon glove box for later use.
[0078] Comparative Example 2 This comparative example provides an electrolyte, the preparation process of which is as follows: Weigh LiPF6 in a high-purity argon glove box and dissolve it in EC:EMC (3:7, v / v) at a molar concentration of 1 mol / L. Weigh 0.5% wt of LiNO3 and add it to the mixture. After stirring with a magnetic stirrer for 12 hours, a white precipitate still remains at the bottom. Store the mixture in a high-purity argon glove box for later use.
[0079] Comparative Example 3 This comparative example provides an electrolyte, the preparation process of which is as follows: Weigh LiPF6 in a high-purity argon glove box and dissolve it in EC:EMC (3:7, v / v) at a molar concentration of 1 mol / L. Weigh 1%wt of PFAS-C4F9 and add it to the solution. Stir with a magnetic stirrer for 12 hours and store in a high-purity argon glove box for later use.
[0080] Table 1
[0081] Application Example 1 This application example provides a battery, the manufacturing process of which is as follows: A positive electrode slurry was formed by mixing NCM811, polyvinylidene fluoride (PVDF), and acetylene black in a mass ratio of 8:1:1, followed by the addition of NMP as a solvent. This slurry was coated onto aluminum foil and dried at 90°C for 8 hours. The electrode was then stamped into a disc with a diameter of 13 mm (the areal density of the active material was 20 mg / cm³).-2 CR2032 button cells were assembled and sealed in a glove box (LS800D type, oxygen and water content ≤ 0.1 ppm). The assembled cells were then left to stand at room temperature for 10 h before electrochemical testing was performed. Lithium metal foil was used as the negative electrode, a polypropylene membrane (Celgard 2400) was used as the separator, and the electrolyte provided in Example 1 was used.
[0082] Application Example 2 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 2 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 2.
[0083] Application Example 3 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 3 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 3.
[0084] Application Example 4 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 4 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 4.
[0085] Application Example 5 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 5 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 5.
[0086] Application Example 6 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 6 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 6.
[0087] Application Example 7 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 7 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 7.
[0088] Application Example 8 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 8 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 8.
[0089] Application Example 9 This application example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Application Example 9 and Application Example 1 is that the electrolyte used is the electrolyte provided in Example 9.
[0090] Comparative Example 4 This comparative example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Comparative Example 4 and Application Example 1 is that the electrolyte used is the electrolyte provided in Comparative Example 1.
[0091] Comparative Example 5 This comparative example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Comparative Example 5 and Application Example 1 is that the electrolyte used is the electrolyte provided in Comparative Example 2.
[0092] Comparative Example 6 This comparative example provides a battery. The preparation process of this battery can be found in Application Example 1. The only difference between Comparative Example 6 and Application Example 1 is that the electrolyte used is the electrolyte provided in Comparative Example 3.
[0093] Performance testing 1. Solubility Test: An electrolyte sample with a composition of ethylene carbonate:diethyl carbonate = 1:1 (volume ratio) containing 2 wt% 1H,1H,2H,2H-perfluorooctyltriethoxysilane and 1 wt% lithium nitrate was prepared. The electrolyte sample was pale yellow, clear, and transparent. An electrolyte sample with a composition of ethylene carbonate:diethyl carbonate = 1:1 (volume ratio) containing only 0.2 wt% lithium nitrate was prepared. The electrolyte sample was white and turbid.
[0094] 2. Cyclic performance test: Cyclic performance test is performed on the batteries provided in Case 1 to Application Case 9 and Comparative Cases 4 to Comparative Case 6.
[0095] The test method was as follows: at 25℃, 0.5C / 0.5C and 1C / 1C charge and discharge were performed respectively; the test results are recorded in Table 2.
[0096] Table 2
[0097] As can be seen from the results in Table 2, compared with the addition of only one of the perfluoroalkylsilane compound and lithium nitrate to the electrolyte, or the addition of neither, the cycle performance of the battery is significantly improved when both perfluoroalkylsilane compound and lithium nitrate are added to the electrolyte. This is because the perfluoroalkylsilane compound can effectively improve the solubility of lithium nitrate in carbonate organic solvents, while lithium nitrate promotes uniform lithium deposition and inhibits the growth of lithium dendrites by forming a stable solid electrolyte interphase (SEI) film during battery cycling, thereby improving the cycle performance of the battery.
[0098] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. An electrolyte, characterized in that, The electrolyte includes lithium salts, carbonate organic solvents, lithium nitrate, and electrolyte additives, wherein the electrolyte additives include perfluoroalkylsilane compounds with the structural formula shown in formula (I): R f -R2-Si(OR1)3 (I); In formula (Ⅰ), R1 and R2 are each independently an alkyl or aryl derivative; R f It is a perfluoroalkyl chain with the structural formula shown in formula (II): C n F 2n+1 Equation (II); In equation (Ⅱ), n is an integer from 4 to 8.
2. The electrolyte according to claim 1, characterized in that, In formula (Ⅰ), R1 and R2 are each independently a derivative of methyl, ethyl, or phenyl; and / or, The perfluoroalkyl chain is C4F9 or C8F. 17 .
3. The electrolyte according to claim 1, characterized in that, In the electrolyte, the mass fraction of lithium nitrate is 0.1 wt% to 1.5 wt%.
4. The electrolyte according to any one of claims 1 to 3, characterized in that, In the electrolyte, the mass fraction of the perfluoroalkylsilane compound is 0.1 wt% to 3 wt%.
5. The electrolyte according to any one of claims 1 to 4, characterized in that, In the electrolyte, the mass ratio of the perfluoroalkylsilane compound to the lithium nitrate is (1~3):
1.
6. The electrolyte according to any one of claims 1 to 5, characterized in that, The lithium salt includes at least one selected from organic lithium salts and inorganic lithium salts; the organic lithium salt includes at least one selected from lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium bis(difluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide; the inorganic lithium salt includes at least one selected from lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, and lithium hexafluorophosphate; and / or, In the electrolyte, the concentration of the lithium salt is 0.1 mol / L to 2 mol / L.
7. The electrolyte according to any one of claims 1 to 6, characterized in that, The carbonate organic solvents include at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, fluoroethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate; and / or, In the electrolyte, the mass fraction of the carbonate organic solvent is 70wt%~85wt%.
8. A battery, characterized in that, Includes the electrolyte as described in any one of claims 1 to 7.
9. The battery according to claim 8, characterized in that, The battery is a lithium metal battery, and the negative electrode of the lithium metal battery is a lithium metal negative electrode.
10. An electrical device, characterized in that, Includes the battery as described in claim 8 or 9.