Electrolyte, battery, and electric device

Abstract

Provided are an electrolyte, a battery, and an electric device. The electrolyte comprises an ether solvent and a lithium salt. The ether solvent comprises at least one of 1,2-di((1'-ethoxy)ethoxy)propane, 2,2-diethoxypropane, 2,2-dimethoxypropane, 1,2-dimethoxypropane, 1,3-dimethoxypropane, and 1,2-diethoxyethane. By using an ether solvent having more sterically hindered functional groups, the solvation ability of ether molecules is adjusted by means of the steric hindrance effect, thereby significantly improving the stability of positive and negative electrodes and coulombic efficiency in an ether electrolyte.

Description

Electrolytes, batteries and electrical devices

[0001] This application claims priority to Chinese Patent Application No. 202410926478.0, filed on July 10, 2024, entitled “An Electrolyte, Battery and Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of batteries, and more particularly to an electrolyte, a battery, and an electrical device. Background Technology

[0003] Currently, under high cutoff voltages (>4.3V), the electrolyte in batteries not only suffers from oxidative decomposition but also from side reactions with the negative electrode material. For example, in lithium metal batteries using a nickel-rich layered oxide cathode paired with a lithium metal anode, the high reactivity of the electrode materials under high voltage conditions leads to severe electrode-electrolyte side reactions, significantly impacting battery life. Summary of the Invention

[0004] To address the technical problems in the prior art, this application provides an electrolyte, a battery, and an electrical device to improve the stability of the electrolyte under high voltage and optimize the cycle stability of the battery.

[0005] An electrolyte comprising an ether solvent and a lithium salt; said ether solvent comprising at least one of 1,2-bis[(1'-ethoxy)ethoxy]propane, 2,2-diethoxypropane, 2,2-dimethoxypropane, 1,2-dimethoxypropane, 1,3-dimethoxypropane, and 1,2-diethoxyethane.

[0006] Optionally, the ether solvent includes 1,2-bis[(1'-ethoxy)ethoxy]propane and 2,2-diethoxypropane, wherein the volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 2,2-diethoxypropane is 1:(0.3-3).

[0007] Optionally, the ether solvent includes 1,2-bis[(1'-ethoxy)ethoxy]propane and 2,2-dimethoxypropane, wherein the volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 2,2-dimethoxypropane is (3-10):1.

[0008] Optionally, the ether solvent includes 1,2-bis[(1'-ethoxy)ethoxy]propane and 1,2-dimethoxypropane, wherein the volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 1,2-dimethoxypropane is (1-5):1.

[0009] Optionally, the ether solvent includes 1,2-bis[(1'-ethoxy)ethoxy]propane and 1,3-dimethoxypropane, wherein the volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 1,3-dimethoxypropane is 1:(0.5-5).

[0010] Optionally, the lithium salt includes at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, lithium fluorosulfonyl-perfluorobutylsulfonylimide, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorophosphate, and lithium nitrate.

[0011] A battery comprising a positive electrode, a negative electrode, a separator, and any one of the above-mentioned electrolytes.

[0012] Optionally, the positive electrode includes at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium-rich manganese-based materials, lithium nickel manganese oxide, and lithium vanadium oxide phosphate.

[0013] Optionally, the negative electrode includes at least one of graphite negative electrode, silicon-oxygen negative electrode, silicon-carbon negative electrode, silicon negative electrode, tin negative electrode, tin oxide negative electrode, tin alloy negative electrode, lithium metal negative electrode, lithium alloy negative electrode and lithium-free negative electrode.

[0014] Optionally, the diaphragm includes at least one of polypropylene, polyethylene, PP / PE / PP composite membrane, polyvinylidene fluoride, polyacrylonitrile, ceramic diaphragm, ceramic polyamide, aramid, and nonwoven fabric.

[0015] A battery includes a positive electrode, a negative electrode, a separator, and an electrolyte; the electrolyte includes any one of the above-mentioned electrolyte solutions; the content of the electrolyte solution in the electrolyte is 0.5 wt.% to 50 wt.%.

[0016] Optionally, the electrolyte is a gel electrolyte or a solid electrolyte; the solid electrolyte is an inorganic solid electrolyte, a polymer solid electrolyte, or a composite solid electrolyte.

[0017] An electrical device that uses any of the above-mentioned batteries as a power source.

[0018] The electrolyte, battery, and electrical device provided in this application use a fluorine-free ether solvent system as the electrolyte. By using an ether solvent with more steric functional groups, the solvation ability of ether molecules is adjusted by utilizing the steric hindrance effect. The increased steric hindrance can control and weaken the solvation ability of oxygen atoms, thereby promoting the presence of anions in the internal solvation shell. The reduction of anions promotes the formation of the inorganic lithium fluoride (LiF) interface and achieves high oxidation stability. This anion-derived LiF mesophase can suppress the growth of lithium dendrites in the negative electrode and minimize the cracking of the positive electrode under high voltage conditions, significantly improving the positive and negative electrode stability and coulombic efficiency of the ether electrolyte. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] This application discloses an electrolyte comprising an ether solvent and a lithium salt, wherein the ether solvent comprises at least one of 1,2-di[(1'-ethoxy)ethoxy]propane (DEEP), 2,2-diethoxypropane (2DEP), 2,2-dimethoxypropane (2DMP), 1,2-dimethoxypropane (1DMP), 1,3-dimethoxypropane (3DMP), and 1,2-diethoxyethane (EGDE).

[0021] Understandably, the electrolyte provided in this embodiment is applicable to lithium batteries, sodium-ion batteries, etc., and belongs to a non-aqueous electrolyte. The ether solvent includes at least one of 1,2-di[(1'-ethoxy)ethoxy]propane (DEEP), 2,2-diethoxypropane (2DEP), 2,2-dimethoxypropane (2DMP), 1,2-dimethoxypropane (1DMP), 1,3-dimethoxypropane (3DMP), and 1,2-diethoxyethane (EGDE).

[0022] Among them, 1,2-bis[(1'-ethoxy)ethoxy]propane (4,6,9-trimethyl-3,5,8,10-tetraoxadodecane, DEEP), CAS No.: 67715-79-1, molecular formula: C 11 H 24 O4, density 0.93 g / cm³ 3 Boiling point 238.2℃ at 760mmHg, molecular weight 220.30600, flash point 40.9℃, refractive index 1.419.

[0023] 2,2-Diethoxypropane (2DEP), CAS No.: 126-84-1, Molecular Formula: C7H 16 O2, molecular weight 132.2, boiling point: 116-117℃ (lit.), density: 0.82 g / mL at 25℃ (lit.), refractive index: n20 / D 1.389 (lit.), flash point: 46°F, storage conditions: 2-8℃.

[0024] 2,2-Dimethoxypropane (2DMP), CAS No. 77-76-9, molecular formula C5H 12 O2, molecular weight 104.15, melting point -47℃. Boiling point 83℃ (lit.), density 0.847 g / mL at 25℃ (lit.), vapor density 3.59 (vs air), vapor pressure 60 mmHg (15.8℃), refractive index n20 / D 1.378 (lit.), flash point 12°F, storage conditions below 30℃, solubility 180 g / L, form: liquid, specific gravity 0.852 (20 / 4℃), color: transparent and colorless, explosive limit: 31%, 58°F, water solubility 18 g / 100 mL (25℃).

[0025] 1,2-Dimethoxypropane (1DMP), CAS No. 7778-85-0, molecular formula C5H 12 O2, molecular weight 104.15, boiling point 96℃ (lit.), density 0.855 g / mL at 25℃ (lit.), vapor pressure 40 mm Hg (20℃), refractive index n20 / D 1.3835 (lit.), flash point 33°F, form: transparent liquid, colorless to almost colorless.

[0026] 1,3-Dimethoxypropane (3DMP), CAS No. 17081-21-9, molecular formula C5H 12 O2, molecular weight 104.15, melting point -82℃, boiling point 106℃, density 0.841±0.06 g / cm³ 3 (Predicted value).

[0027] 1,2-Diethoxyethane (EGDE), CAS No. 629-14-1, molecular formula C6H 14O2, molecular weight 118.17, melting point -74℃, boiling point 121℃ (lit.), density 0.842 g / mL at 25℃ (lit.), vapor pressure 9.4 mmHg (20℃), refractive index n20 / D 1.3923 (lit.), flash point 69°F, storage conditions below 30℃, solubility 34 g / L, form: liquid, color: transparent and colorless.

[0028] These ether solvents use ethyl (EGDE), propyl (3DMP), or -CH3 (DEEP, 2DEP, 2DMP, 1DMP) groups between the two oxygen atoms to increase the steric hindrance of the ether structure, regulate the solvation structure of the ether molecule, improve its oxidation resistance, and retain the traditional ether structure -CH2CH2O- for stabilizing lithium metal anodes. The increased steric hindrance of these ether solvents can control and weaken the solvation ability of oxygen atoms, thereby promoting the presence of anions in the internal solvation shell. Anion reduction promotes the formation of the inorganic lithium fluoride (LiF) interface and achieves high oxidation stability. This anion-derived LiF mesophase can suppress lithium dendrite growth at the anode and minimize cracking of the cathode under high voltage conditions, significantly improving the anode and cathode stability and coulombic efficiency of the ether electrolyte, resulting in excellent cycle stability of the battery system at high cutoff voltages.

[0029] In some examples, the ether solvent includes DEEP + 2DEP, with a volume ratio of DEEP to 2DEP of 1:(0.3–3). Both DEEP and 2DEP have high boiling points and are not easily evaporated at high temperatures, which can reduce solvent evaporation and maintain the stability of the electrolyte.

[0030] In some examples, the ether solvent includes DEEP + 2DMP, with a volume ratio of DEEP to 2DMP of (3–10):1. Here, 2DMP has a lower melting point, which can improve the low-temperature performance of the battery.

[0031] In some examples, the ether solvent includes DEEP + 1DMP, with a volume ratio of DEEP to 1DMP of (1–5):1.

[0032] In some examples, the ether solvent includes DEEP+3DMP, with a volume ratio of DEEP to 3DMP of 1:(0.5 to 5).

[0033] Lithium salts can be selected from inorganic or organic lithium salts suitable for batteries, such as lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Lithium salts can effectively improve the ionic conductivity of the electrolyte, enhance its voltage withstand performance, and improve lithium metal / graphite compatibility. Firstly, after dissolving in a mixed solvent, lithium salts dissociate into lithium ions and corresponding anions. These lithium ions act as charge carriers, moving within the electrolyte and providing channels for charge transfer within the battery. Therefore, adding lithium salts can improve the ionic conductivity of the electrolyte, contributing to improved charge-discharge efficiency and power performance of the battery. Secondly, lithium salt anions possess high electrochemical stability. Within the battery's operating voltage range, these anions are less prone to oxidation or reduction reactions, reducing the occurrence of side reactions. This prevents electrolyte decomposition at high voltages, thereby improving the electrolyte's voltage withstand performance and ensuring stable battery operation over a wide voltage range. Third, during the initial cycling of the battery, the anions of lithium salts or their reduction products can form a stable solid electrolyte interphase (SEI) film on the electrode surface (SEI on the negative electrode, CEI on the positive electrode), especially for active electrode materials such as lithium metal and graphite. This interphase film can prevent other components in the electrolyte from further reacting with the electrode, reduce the growth of lithium dendrites, protect the electrode materials from electrolyte corrosion, enhance the compatibility of lithium metal and graphite, and improve the safety and cycle stability of the battery.

[0034] The electrolyte provided in this embodiment is a fluorine-free ether solvent system. By using an ether solvent with more steric functional groups, the solvation ability of ether molecules is adjusted by utilizing the steric hindrance effect. The increased steric hindrance can control and weaken the solvation ability of oxygen atoms, thereby promoting the presence of anions in the internal solvation shell. The reduction of anions promotes the formation of the inorganic lithium fluoride (LiF) interface and achieves high oxidation stability. This anion-derived LiF mesophase can suppress the growth of lithium dendrites in the negative electrode and minimize the cracking of the positive electrode under high voltage conditions, significantly improving the positive and negative electrode stability and coulombic efficiency of the ether electrolyte.

[0035] In some examples, the lithium salt includes at least one of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, lithium fluorosulfonyl-perfluorobutylsulfonylimide, lithium bis(oxalato)borate, lithium difluorooxalato)borate, and lithium difluorophosphate.

[0036] Understandably, lithium salts can be selected from inorganic or organic lithium salts suitable for batteries, such as lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide (LiTNFSI), lithium fluorosulfonyl-perfluorobutylsulfonylimide (LiFNFSI), lithium bis(oxalatoborate)borate (LiBOB), lithium difluorophosphate (LiPO2F2), etc.

[0037] The lithium salt provided in this embodiment can effectively improve the ionic conductivity of the electrolyte, enhance the electrolyte's voltage resistance, and improve lithium metal / graphite compatibility.

[0038] In some examples, the concentration of the lithium salt in the electrolyte is 0.5 mol / L to 3 mol / L.

[0039] Understandably, the lithium salt concentration can be determined according to actual needs, such as 0.5 mol / L to 3 mol / L. Preferably, the concentration of lithium salt in the electrolyte can be 1 mol / L or 1.5 mol / L.

[0040] This application also discloses a battery, including a positive electrode, a negative electrode, a separator, and any one of the above-mentioned electrolytes.

[0041] Understandably, the electrolyte provided in the previous embodiment can be used in conjunction with a positive electrode, a negative electrode, and a separator to prepare a battery. The positive electrode is one of the core components of the battery, significantly affecting its energy density. The positive electrode can be selected from at least one of lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel oxide (LNO), ternary materials (NCM, NCA), lithium-rich manganese-based materials (LMR), lithium nickel manganese oxide (LNMO), and lithium vanadium oxide phosphate (Li3V2(PO4)3, LiVOPO4). The negative electrode is also one of the core components of the battery, interacting with the electrolyte to promote the insertion and extraction of metal cations. The negative electrode can be selected from at least one of the following: graphite negative electrode, silicon-oxygen negative electrode, silicon-carbon negative electrode, silicon negative electrode, tin negative electrode, tin oxide negative electrode, tin alloy negative electrode (Sn-Fe, Sn-Co, Sn-Cu, etc.), lithium metal negative electrode, lithium alloy negative electrode (Li-Ag, Li-Al, Li-Sn, Li-Mg, Li-Zn, Li-In, Li-Ga, etc.), and lithium-free negative electrode. The separator is a very thin porous material located between the positive and negative electrodes of the battery, and can be selected from at least one of the following: polypropylene (PP), polyethylene (PE), PP / PE / PP composite membrane, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), ceramic separator, polyimide (PI), aramid (AF), and nonwoven fabric.

[0042] The battery provided in this embodiment can be manufactured as a liquid stacked battery, a liquid wound battery, or a liquid cylindrical battery. Due to the use of a higher-performance electrolyte, the battery system has excellent cycle stability at high cutoff voltage.

[0043] This application also discloses a battery, including a positive electrode, a negative electrode, a separator, and a gel electrolyte; the gel electrolyte includes any of the above-mentioned electrolytes; the content of the electrolyte in the electrolyte is 0.5 wt.% to 50 wt.%. In this embodiment, the battery can be a semi-solid battery, such as a semi-solid stacked battery, a semi-solid wound battery, or a semi-solid cylindrical battery, wherein the electrolyte can be a gel electrolyte composed of a solid electrolyte and an electrolyte, and the content of the electrolyte in the electrolyte is 0.5 wt.% to 50 wt.%. The solid electrolyte can be selected from inorganic solid electrolytes (oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes), polymer solid electrolytes, and composite solid electrolytes (inorganic filler + polymer matrix). Solid electrolytes have higher mechanical strength and thermal stability, can better resist deformation and temperature changes, and can provide better safety performance. Compared with liquid electrolytes, gel electrolytes reduce the risk of leakage and improve safety.

[0044] This application also discloses an electrical device that uses any of the above-mentioned batteries as a power source.

[0045] Example

[0046] Preparation of electrolyte

[0047] Add the corresponding lithium salt to the solvents shown in Table 1 to achieve the lithium salt concentrations shown in Table 1, and stir at room temperature for 12 hours before use.

[0048] In Comparative Example 1, the solvent used was 2-dimethoxyethane (DME).

[0049] Preparation of positive electrode

[0050] Lithium nickel cobalt manganese oxide (NCM811), CNT (carbon nanotubes), and PVDF (polyvinylidene fluoride) binder are mixed in a mass ratio of 97:1.5:1.5. The mixture is thoroughly stirred in NMP solvent (N-methyl-2-pyrrolidone) to form a uniform positive electrode slurry. This slurry is coated onto at least one side of an aluminum foil current collector, and after drying, rolling, and die-cutting, a satisfactory positive electrode sheet is obtained.

[0051] The negative electrode is a lithium metal negative electrode.

[0052] The diaphragm uses PE porous polymer film (Polyethylene) as the diaphragm substrate;

[0053] Lithium battery manufacturing

[0054] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The stacked electrodes and separator are then placed in a pre-formed aluminum-plastic film bag. The non-aqueous electrolyte prepared above is injected into the baked and dried battery cell. After vacuum sealing, settling, and formation processes, a 1Ah lithium battery is obtained.

[0055] Performance testing

[0056] 1. Electrolyte oxidation potential test: The oxidation potential of the electrolyte membrane was tested using the linear scanning potentiometric method with an EC-Lab electrochemical workstation. The test voltage range was 2.5–6 V, and the scan rate was 1 mV·s. -1 The method uses a device structure of "stainless steel sheet | diaphragm | lithium sheet" for testing, with the stainless steel sheet as the working electrode and the lithium sheet as the reference electrode.

[0057] 2. Cell cycle performance test: Under the voltage range of 3.0V to 4.3V and temperature of 25℃, the battery is subjected to 0.5C / 0.5D cycle charge and discharge test, and the capacity retention rate of the battery is recorded after 100 cycles.

[0058] Table 1 Electrolyte formulation and battery performance

[0059] As shown in Table 1, by replacing the short-chain methyl -CH3 with the extended carbon chain ethyl CH3-CH2- or introducing -CH3 into the side chain to increase the steric hindrance of the ether structure, the oxidation resistance of traditional short-chain ethers is effectively improved while retaining the stable structure -CH2CH2O- for lithium metal anodes, and the cycle stability of ether electrolytes in high-voltage cathode systems is significantly improved.

[0060] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An electrolyte, characterized in that, It includes ether solvents and lithium salts; the ether solvents include at least one of 1,2-bis[(1'-ethoxy)ethoxy]propane, 2,2-diethoxypropane, 2,2-dimethoxypropane, 1,2-dimethoxypropane, 1,3-dimethoxypropane, and 1,2-diethoxyethane.

2. The electrolyte as described in claim 1, characterized in that, The ether solvents include 1,2-bis[(1'-ethoxy)ethoxy]propane and 2,2-diethoxypropane, with a volume ratio of 1:(0.3-3) for 1,2-bis[(1'-ethoxy)ethoxy]propane and 2,2-diethoxypropane.

3. The electrolyte as described in claim 1, characterized in that, The ether solvents include 1,2-bis[(1'-ethoxy)ethoxy]propane and 2,2-dimethoxypropane, with a volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 2,2-dimethoxypropane of (3 to 10):

1.

4. The electrolyte as described in claim 1, characterized in that, The ether solvents include 1,2-bis[(1'-ethoxy)ethoxy]propane and 1,2-dimethoxypropane, with a volume ratio of 1,2-bis[(1'-ethoxy)ethoxy]propane to 1,2-dimethoxypropane of (1-5):

1.

5. The electrolyte as described in claim 1, characterized in that, The ether solvents include 1,2-bis[(1'-ethoxy)ethoxy]propane and 1,3-dimethoxypropane, with a volume ratio of 1:(0.5-5) of 1,2-bis[(1'-ethoxy)ethoxy]propane to 1,3-dimethoxypropane.

6. The electrolyte as described in claim 1, characterized in that, The lithium salt includes at least one of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethanesulfonyl-perfluorobutylsulfonylimide, lithium fluorosulfonyl-perfluorobutylsulfonylimide, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorophosphate, and lithium nitrate.

7. A battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte as described in any one of claims 1 to 6.

8. The battery as claimed in claim 7, characterized in that, The positive electrode includes at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium-rich manganese-based materials, lithium nickel manganese oxide, and lithium vanadium oxide phosphate.

9. The battery as claimed in claim 7, characterized in that, The negative electrode includes at least one of graphite negative electrode, silicon-oxygen negative electrode, silicon-carbon negative electrode, silicon negative electrode, tin negative electrode, tin oxide negative electrode, tin alloy negative electrode, lithium metal negative electrode, lithium alloy negative electrode and lithium-free negative electrode.

10. The battery as claimed in claim 7, characterized in that, The diaphragm includes at least one of polypropylene, polyethylene, PP / PE / PP composite membrane, polyvinylidene fluoride, polyacrylonitrile, ceramic diaphragm, ceramic polyamide, aramid, and nonwoven fabric.

11. A battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte; the electrolyte includes an electrolyte as described in any one of claims 1 to 6; the content of the electrolyte in the electrolyte is 0.5 wt.% to 50 wt.%.

12. The battery as claimed in claim 11, characterized in that, The electrolyte is a gel electrolyte or a solid electrolyte; the solid electrolyte is an inorganic solid electrolyte, a polymer solid electrolyte, or a composite solid electrolyte.

13. An electrical appliance, characterized in that, The battery described in any one of claims 7 to 12 is used as the power source.

Images