High-voltage electrolyte and application thereof in lithium-rich manganese-based positive electrode system

Abstract

The invention provides an application of a high-voltage electrolyte in a lithium-rich manganese-based positive electrode system battery. According to the high-voltage electrolyte provided by the invention, the high-voltage tolerance of a solvent in a lithium-rich manganese-based positive electrode material system is fully considered, and a plurality of positive and negative electrode film-forming additives are used, so that interface synergistic film formation is promoted, and the balance of organic / inorganic components of an interface solid electrolyte layer is regulated and controlled; and the component proportion of the inorganic composition and the organic composition is finely regulated and controlled. By regulating and controlling the proportion of organic / inorganic components of the positive and negative electrode interface electrolyte layer and characterizing and recognizing F, P, B and S components, a large number of DOE tests of an electrolyte system and additives can be reduced, the cost can be remarkably reduced, meanwhile, the membrane separation effect of all element components is clarified, complicated design of electrolyte solvents and additive materials can be avoided, and the application prospect is wide. The purpose of solving complex problems through a simple scheme is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a high voltage electrolyte and application thereof in a lithium-rich manganese-based positive electrode system. Background Art

[0002] Among many energy devices, lithium-ion batteries (LIBs) are considered to be an important object for reconstructing the future energy system due to their advantages such as stable operating voltage, long cycle life and high energy density. At present, lithium-ion batteries are widely used in our daily lives and have become the dominant power source for portable electronic products and electronic transportation. It is well known that carbonate organics have been used as electrolytes for systems such as lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and ternary materials for decades, and have been successfully commercialized and widely used in the fields of consumer batteries and power batteries.

[0003] Lithium-rich manganese-based cathode materials are considered to be one of the key cathode materials for next-generation lithium-ion batteries due to their high energy density and low cost. However, during the first charge, lithium-rich layered oxides have an activation platform at around 4.5V, which makes Li 2 MnO 3 The components are activated and transformed into electrochemically active layered MnO 2 Therefore, the charge cut-off potential of the electrode material usually exceeds 4.6V, or even as high as 4.8V. Such a high potential will bring severe challenges to the electrolyte. Especially in high temperature environment, it aggravates the gas production of high voltage interface side reactions and the loss of active lithium, causing safety hazards to storage and even causing thermal runaway.

[0004] Therefore, it becomes a problem to be solved to provide a lithium-rich manganese-based positive electrode system battery that can reduce the gas production caused by high-voltage interface side reactions and the loss of active lithium under high potential, especially high temperature environment, and ensure battery safety. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an application of a high-voltage electrolyte in a lithium-rich manganese-based positive electrode system battery. The present invention applies a specific type of high-voltage electrolyte to a lithium-rich manganese-based positive electrode system battery, which can reduce the gas production of high-voltage interface side reactions and the loss of active lithium, ensure battery safety, and has low preparation cost and simple method.

[0006] The present invention provides an application of a high-voltage electrolyte in a lithium-rich manganese-based positive electrode system battery, wherein the lithium-rich manganese-based positive electrode system battery comprises a positive electrode, a negative electrode, a high-voltage electrolyte and a separator;

[0007] The high voltage electrolyte comprises a solvent, a lithium salt and an additive, wherein the additive comprises fluorine, boron, phosphorus and sulfur;

[0008] After the lithium-rich manganese-based positive electrode system battery is charged and discharged for the first time at a high voltage of more than 4.55V, the mass ratio of the organic component of the electrolyte interface layer to the inorganic component of the electrolyte interface layer is (0.6-1):1.

[0009] Preferably, the organic component of the electrolyte interface layer includes a compound containing one or more bonds of C=O, CO, BO, and LiSO 3 One or more of R, R is one or more of aromatic groups or hydrocarbon groups;

[0010] The inorganic components of the electrolyte interface layer include POF, LiF, Li x BO y F z 、LiPF 6 , Li 3 PO 4 , Li x PO y F z and LiP x F y One or more of x BO y In F, x, y and z satisfy x+3-2y-z=0; in Li x PO y F z In LiP, x, y and z satisfy x+5-2y-z=0; x F y In Li, x and y satisfy 1+5x-y=0; x BO y F, Li x PO y F z and LiP x F y In this equation, x, y, and z are any natural real numbers that satisfy the law of conservation of charge.

[0011] Preferably, the additives include fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds and sulfur-containing compounds;

[0012] The fluorine-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the fluorine-containing compound includes one or more compounds containing one or more bonds of FO, FP, and FB;

[0013] The boron-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the boron-containing compound includes one or more compounds containing one or more bonds among BO, BP, and BF;

[0014] The phosphorus-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the phosphorus-containing compound includes one or more compounds containing one or more bonds of PO, PB, and PF;

[0015] The sulfur-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the sulfur-containing compound includes one or more compounds containing one or more bonds of SO, SC, and SS.

[0016] Preferably, the fluorine-containing compound comprises lithium hexafluoroarsenate (LiAsF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorooxalatoborate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorophosphate (LiDFP), methyl difluoroacetate (MFA), tris(pentafluorophenyl)borane (TPFPB), tris(2,2,2-trifluoroethyl)phosphite (TTFP), ethoxy-pentafluoro-cyclotriphosphazene (PFN), fluorinated ethyl phosphate (FEP), fluorinated phosphate tris(2,2,2-trifluoroethyl) phosphate (TFP), fluorosulfonyl isocyanate (FI), 1,2-bis(difluoromethylsilyl)ethane (FSE), 2,3-difluorotoluene (DFT) and trifluoroacetylthiophene (TFPN);

[0017] And / or, the boron-containing compound includes lithium tetrafluoroborate (LiBF 4 ), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium 4-benzonitrile trimethylborate (LBTB), trimethyl borate (TMB), triethyl borate (TEB), tripropyl borate (TPB), tris(trimethyl)silaneborate (TMSB), tris(2-nitrileethyl)borate (TCEB), tris(2,2,2-trifluoroethyl)borate (TTFEB), 3-thiopheneboric acid (TB), pyridine-boron trifluoride (PBF), methyliminodiacetate (ADM) and tris(pentafluorophenyl)borane (TPFPB);

[0018] And / or, the phosphorus-containing compound of the electrolyte additive includes one or more of lithium difluorophosphate (LiDFP), lithium difluorobisoxalate phosphate (LiDFBOP), lithium tetrafluoro(fluoropropylene glycol) phosphate (LFMP), (trimethylsilyl) phosphite (TMSPi), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), tetraphenylphosphine amide (TPPA), 1,2-bis(diphenylphosphino)ethane (DPPE), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trimethylsilyl) phosphate (TTSP), triethyl phosphite (TEP), tripropargyl phosphate (TPP), tris(2,2,2-trifluoroethyl) phosphite (TTFP), dimethyl methylphosphonate (DMMP), diethyl phenylphosphonate (DPP) and bis(2,2,2-trifluoroethyl) methylphosphonate (TFMP);

[0019] And / or, the sulfur-containing compound includes one or more of 1,3-propane sultone (PS), vinyl sulfite (ES), dimethyl sulfite (DMS), diethyl sulfite (DES), propylene sulfite (TMS), vinyl vinyl sulfite (VES), vinyl sulfate (DTD), 1,3-propylene sultone (PST), 1,3-propylene glycol cyclic sulfate (PCS), trifluoromethylphenyl sulfide (PTS), dimethanesulfonylmethane (DMSM), methylene methane disulfonate (MMDS), 1,1-sulfonyldiimidazole (SDM), 3-(phenylsulfonyl)propionitrile (PSPN), dimethyl sulfoxide (DMSO), sulfolane (SL), and 1,2Λ6-oxathiolane-2,2,5-trione (SPA).

[0020] Preferably, after the lithium-rich manganese-based positive electrode system battery has been charged and discharged for 200 times at 4.55V or above in a high temperature environment of 45°C, SEM and AFM scanning are performed on the negative electrode side, and the SEM morphology of the negative electrode surface is smooth and free of cracks, and there is no obvious particle attachment; AFM detection of the negative electrode surface fluctuation Fluc. ≤200nm.

[0021] Preferably, the solvent includes one or more of an organic ester solvent, a fluorinated organic ester solvent, an organic ether solvent and a fluorinated organic ether solvent.

[0022] Preferably, the organic ester solvent includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl vinyl carbonate (EMC), methyl propyl carbonate (MPC), di-n-butyl carbonate (DBC), methyl butyl carbonate (BMC), dipropyl carbonate (DPC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), 1,4-butyrolactone (GBL), methyl ester (PA), methyl formate (MF), ethyl acetate (MA) and methyl propionate (MP);

[0023] The fluorinated organic ester solvent includes one or more compounds of the organic ester solvent after fluorination;

[0024] The organic ether solvent includes one or more of dibutyl ether (DBE), ethylene glycol dimethyl ether (DME), dimethoxymethane (DMM), ethylene glycol diethyl ether (DEE), triethylene glycol dimethyl ether (G3), tetrahydrofuran (THF), 1,3-dioxolane (DOL) and 1,4-dioxane (1,4DX);

[0025] The fluorinated organic ether solvent includes one or more compounds of the organic ether solvent after fluorination.

[0026] Preferably, in the electrolyte solvent, the mass ratio of the fluorinated organic ester solvent and the fluorinated organic ether solvent to the mass ratio of the electrolyte solvent is higher than 10wt.%,

[0027] In the electrolyte, the content of the additive is 0.1wt% to 5wt%.

[0028] Preferably, the negative electrode is metallic lithium, the electrolyte is the electrolyte according to any one of claims 1 to 8, and the separator is selected from a polypropylene separator or a polyethylene separator.

[0029] Preferably, the first charging voltage of the lithium-rich manganese-based positive electrode system battery needs to be higher than 4.55V.

[0030] Compared with the prior art, the present invention provides an application of a high-voltage electrolyte in a lithium-rich manganese-based positive electrode system battery, wherein the lithium-rich manganese-based positive electrode system battery comprises a positive electrode, a negative electrode, a high-voltage electrolyte and a separator; the high-voltage electrolyte comprises a solvent, a lithium salt and an additive, and the additive comprises fluorine, boron, phosphorus and sulfur; after the lithium-rich manganese-based positive electrode system battery is charged and discharged for the first time at a high voltage of more than 4.55V, the mass ratio of the organic component of the electrolyte interface layer to the inorganic component of the electrolyte interface layer is (0.6~1):1.

[0031] The high-voltage electrolyte provided by the present invention fully considers the high-voltage tolerance of the solvent in the lithium-rich manganese-based positive electrode material system, uses a variety of positive and negative electrode film-forming additives, promotes interfacial synergistic film formation, regulates the balance of organic / inorganic components in the interfacial solid electrolyte layer, and finely regulates the component ratio of inorganic and organic components. By regulating the ratio of organic / inorganic components in the positive and negative electrode interface electrolyte layer and characterizing and identifying the components containing F, P, B and S, a large number of DOE tests of the electrolyte system and additives can be reduced, significantly reducing costs, while clarifying the film-forming effects of each element component, and avoiding the complicated design of electrolyte solvents and additive materials, achieving the purpose of solving complex problems with simple solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of high voltage electrolyte and its film formation protection in lithium-rich manganese-based positive electrode system battery;

[0033] Figure 2 The following are SEM images of the positive electrode sheets prepared in the examples and comparative examples, wherein: Figure 2 (ad) are SEM images of positive electrode sheets of Examples 2, 15, 25, and 28, and (ej) are SEM images of positive electrode sheets of Comparative Examples 1, 18, 20, 21, 22, and 23;

[0034] Figure 3 The following are SEM images of the negative electrode sheets prepared in the examples and comparative examples, wherein: Figure 3 (ad) are SEM images of negative electrode sheets of Examples 2, 15, 25, and 28, and (ej) are SEM images of negative electrode sheets of Comparative Examples 1, 18, 20, 21, 22, and 23;

[0035] Figure 4 The SEM images of the cross sections of the negative electrode sheets prepared in the examples and comparative examples are shown in FIG. Figure 4 (a) and (b) are SEM images of the cross-section of the negative electrode sheet of Comparative Example 1, and (c) and (d) are SEM images of the cross-section of the negative electrode sheet of Example 2;

[0036] Figure 5 The AFM images of the negative electrode sheets prepared in the examples and comparative examples are shown in FIG. Figure 5 (a) is the AFM image of the negative electrode of Comparative Example 1, and (b) is the AFM image of the negative electrode of Example 2;

[0037] Figure 6 The first charge and discharge curves of the batteries prepared in the examples and comparative examples are shown in FIG. Figure 6 (ad) are the first charge and discharge curves of the batteries of Examples 2, 15, 25, and 28, and (ej) are the first charge and discharge curves of the batteries of Comparative Examples 1, 18, 20, 21, 22, and 23;

[0038] Figure 7 The following are the cycle test results of the batteries prepared in the examples and comparative examples, wherein: Figure 7 (ad) are the cycle test results of the batteries prepared in Examples 2, 15, 25, and 28, and (ej) are the cycle test results of the batteries prepared in Comparative Examples 1, 18, 20, 21, 22, and 23. DETAILED DESCRIPTION

[0039] The present invention provides an application of a high-voltage electrolyte in a lithium-rich manganese-based positive electrode system battery, wherein the lithium-rich manganese-based positive electrode system battery comprises a positive electrode, a negative electrode, a high-voltage electrolyte and a separator;

[0040] The high voltage electrolyte comprises a solvent, a lithium salt and an additive, wherein the additive comprises fluorine, boron, phosphorus and sulfur;

[0041] After the lithium-rich manganese-based positive electrode system battery is charged and discharged for the first time at a high voltage of more than 4.55V, the mass ratio of the organic component of the electrolyte interface layer to the inorganic component of the electrolyte interface layer is (0.6-1):1.

[0042] The additives in the high voltage electrolyte of the present invention include fluorine, boron, phosphorus and sulfur. In some specific embodiments of the present invention, the additives include fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds and sulfur-containing compounds.

[0043] In some specific embodiments of the present invention, the high voltage electrolyte comprises:

[0044] 0.1wt% to 5wt% of a fluorine-containing compound;

[0045] 0.1 wt% to 5 wt% of a boron-containing compound;

[0046] 0.1wt% to 5wt% of a phosphorus-containing compound;

[0047] 0.1wt% to 5wt% of sulfur-containing compounds.

[0048] Specifically, the high voltage electrolyte includes 0.1wt% to 5wt% of a fluorine-containing compound, which may be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any value between 0.1wt% and 5wt%, preferably 0.1wt% to 1wt%. The fluorine-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the fluorine-containing compound includes one or more compounds containing one or more bonds of FO, FP, and FB; more preferably, the fluorine-containing compound includes lithium hexafluoroarsenate (LiAsF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorooxalatoborate (LiDFOB), lithium bis(fluorosulfonyl imide) salt (LiFSI), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium difluorophosphate (LiDFP), methyl difluoroacetate (MFA), tris(pentafluorophenyl) borane (TPFPB), tris(2,2,2-trifluoroethyl) phosphite (TTFP), ethoxy-pentafluoro-cyclotriphosphazene (PFN), fluorinated ethyl phosphate (FEP), fluorinated phosphate tris(2,2,2-trifluoroethyl) phosphate (TFP), fluorosulfonyl isocyanate (FI), 1,2-bis(difluoromethylsilyl) ethane (FSE), 2,3-difluorotoluene (DFT) and trifluoroacetylthiophene (TFPN) One or more; more preferably lithium tetrafluoroborate (LiBF 4), lithium difluorooxalatoborate (LiDFOB), lithium bis(trifluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorophosphate (LiDFP) and trifluoroacetylthiophene (TFPN).

[0049] The high voltage electrolyte includes 0.1wt% to 5wt% of a boron-containing compound, which may be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any value between 0.1wt% and 5wt%, preferably 1wt% to 5wt%. The boron-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the boron-containing compound includes one or more compounds containing one or more bonds of BO, BP, and BF; more preferably, the boron-containing compound includes lithium tetrafluoroborate (LiBF 4 ), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), 4-benzonitrile trimethylborate (LBTB), trimethyl borate (TMB), triethyl borate (TEB), tripropyl borate (TPB), tris(trimethyl)silaneborate (TMSB), tris(2-nitrileethyl)borate (TCEB), tris(2,2,2-trifluoroethyl)borate (TTFEB), 3-thiopheneboric acid (TB), pyridine-boron trifluoride (PBF), methyliminodiacetate (ADM) and tris(pentafluorophenyl)borane (TPFPB); more preferably, lithium tetrafluoroborate (LiBF 4 ), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), triethyl borate (TEB), tripropyl borate (TPB) and tris(trimethyl)silaneborate (TMSB) One or more.

[0050] The high voltage electrolyte includes 0.1wt% to 5wt% of a phosphorus-containing compound, which may be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any value between 0.1wt% and 5wt%, preferably 0.1wt% to 1.5wt%. The phosphorus-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the phosphorus-containing compound includes one or more compounds containing one or more bonds of PO, PB, and PF; more preferably, the phosphorus-containing compound of the electrolyte additive includes lithium difluorophosphate (LiDFP), lithium difluorobis(oxalate)phosphate (LiDFBOP), lithium tetrafluoro(fluoropropylene glycol)phosphate (LFMP), (trimethylsilyl)phosphite (TMSPi), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), tetraphenylphosphine amide (TPPA), 1,2-bis(diphenylphosphine)ethane (DPPE), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trifluoromethyl)phosphite (TMSPi), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trifluoromethyl)phosphite (TMSPi), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trifluoromethyl)phosphite (TMSPi), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trifluoromethyl)phosphite (TMSPi), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trifluoromethyl)phosphite (TMSPi), tris(trifluoromethyl)phosphite (TPPA), tris(trifluoromethyl)phosphine ... One or more of (trimethylsilyl) phosphate (TTSP), triethyl phosphite (TEP), tripropargyl phosphate (TPP), tri(2,2,2-trifluoroethyl) phosphite (TTFP), dimethyl methylphosphonate (DMMP), diethyl phenylphosphonate (DPP) and bis(2,2,2-trifluoroethyl) methylphosphonate (TFMP); further preferably one or more of lithium difluorophosphate (LiDFP), lithium difluorobisoxalatophosphate (LiDFBOP), (trimethylsilyl) phosphite (TMSPi), ethoxy(pentafluoro)cyclotriphosphazene (PFPN) and tetraphenylphosphine amide (TPPA).

[0051] The high voltage electrolyte includes 0.1wt% to 5wt% of a sulfur-containing compound, which may be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any value between 0.1wt% and 5wt%, preferably 0.1wt% to 1wt%. The sulfur-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the sulfur-containing compound includes one or more compounds containing one or more bonds of SO, SC, and SS. More preferably, the sulfur-containing compound includes 1,3-propane sultone (PS), vinyl sulfite (ES), dimethyl sulfite (DMS), diethyl sulfite (DES), propylene sulfite (TMS), vinyl vinyl sulfite (VES), vinyl sulfate (DTD), 1,3-propylene sultone (PST), 1,3-propylene glycol cyclosulfate (PCS), trifluoromethylphenyl sulfide (PTS) , dimethanesulfonyl methane (DMSM), methylene methane disulfonate (MMDS), 1,1-sulfonyldiimidazole (SDM), 3-(phenylsulfonyl) propionitrile (PSPN), dimethyl sulfoxide (DMSO), cyclopentane (SL), 1,2Λ6-oxathiolane-2,2,5-trione (SPA) One or more, further preferably 1,3-propane sultone (PS), propene sulfite (TMS), vinyl vinyl sulfite (VES), vinyl sulfate (DTD), 1,3-propene sultone (PST) and methylene methane disulfonate (MMDS) One or more.

[0052] In some embodiments of the present invention, the additive is selected from lithium difluorophosphate (LiDFP), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluoroborate (LiBF 4 ) and 1,3-propane sultone (PS) mixed additives, or lithium difluorophosphate (LiDFP), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluoroborate (LiBF 4 ), a mixed additive of lithium bis(fluorosulfonyl)imide (LiFSI) and 1,3-propane sultone (PS), or lithium difluorophosphate (LiDFP), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluoroborate (LiBF 4 ) and dimethyl sulfoxide (DMSO) as a mixed additive, or lithium difluorophosphate (LiDFP), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluoroborate (LiBF 4 ), lithium difluorobis(oxalate)phosphate (LiDFBOP), (trimethylsilyl)phosphite (TMSPi), lithium difluorooxalateborate (LiDFOB), lithium tetrafluoroborate (LiBF4 ) and 1,3-propane sultone (PS) mixed additives, or lithium difluorophosphate (LiDFP), lithium bis(oxalatoborate) (LiBOB), triethyl borate (TEB), lithium tetrafluoroborate (LiBF 4 ) and 1,3-propane sultone (PS) mixed additive.

[0053] In some specific embodiments of the present invention, in the electrolyte, the total content of additives is 0.1wt% to 5wt%, and can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any value between 0.1wt% and 5wt%.

[0054] See also Figure 1 , Figure 1 Schematic diagram of high-voltage electrolyte and its film formation protection in lithium-rich manganese-based positive electrode system batteries.

[0055] The above electrolyte was applied to a lithium-rich manganese-based positive electrode material system battery. After the first high-voltage charge and discharge above 4.55V, X-ray photoelectron spectroscopy was performed on the positive electrode electrolyte interface layer O, F, P, B and S. Peak fitting revealed that C=O, CO, POF, BO, LiF, Li x BO y F z 、LiPF 6 , Li 3 PO 4 ,LiP x F y , Li x PO y F z and LiSO 3 Wherein, R is one or more of an aromatic group or a hydrocarbon group, preferably a C1 to C5 hydrocarbon group, in Li x BO y In F, x+3-2y-z=0 is satisfied; in Li x PO y F z In LiP, x+5-2y-z=0 is satisfied; x F y , 1+5x-y=0 is satisfied; where x, y, z are any natural real numbers that conform to the law of conservation of material charge.

[0056] Put C=O, CO, BO, LiSO 3 R is classified as the organic component of the electrolyte interface layer (Organic, referred to as O), POF, LiF, Li x BOy F z 、LiPF 6 , Li 3 PO 4 , Li x PO y F z and LiP x F y The above components are classified as inorganic components of the electrolyte interface layer (Inorganic, referred to as I), and the mass ratio (O / I) of the organic components of the electrolyte interface layer to the inorganic components of the electrolyte interface layer is (0.6-1):1, which can be 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, or any value between (0.6-1):1.

[0057] Under the action of high voltage (≥4.55V), the solvent, lithium salt and additives work synergistically to promote the balanced growth of organic (O) / inorganic (I) composition in the CEI / SEI layer on the electrode surface interface, effectively inhibiting the corrosion of the electrode by the electrolyte in a high temperature and high pressure environment when 0.6≤O / I≤1, and significantly improving the uniform deposition of metallic lithium, thereby improving the cycle stability and safety of the lithium-rich manganese-based positive electrode in a high voltage (≥4.55V) system.

[0058] Among the inorganic components obtained by X-ray photoelectron spectrum peak fitting, the LiF ratio is controlled, Li 3 PO 4 Proportion, Li x PO y F and Li x BO y F z Proportion.

[0059] In the organic components obtained by X-ray photoelectron spectrum peak fitting, the C=O ratio, CO ratio, BO and LiSO 3 R z Proportion.

[0060] Furthermore, the above-mentioned electrolyte is applied to a lithium-rich manganese-based positive electrode material system. After the first charge and discharge at a high voltage of more than 4.55V, and 200 charge and discharge cycles at more than 4.55V in a high temperature environment of 45°C, SEM and AFM scans are performed on the positive and negative sides. The SEM morphology of the negative electrode sheet is smooth and free of cracks, and there is no obvious particle attachment; AFM detects that the surface undulation of the negative electrode sheet is ≤200nm, preferably ≤150nm, and more preferably ≤100nm.

[0061] The high voltage electrolyte further comprises a solvent, and the solvent comprises one or more of an organic ester solvent, a fluorinated organic ester solvent, an organic ether solvent, and a fluorinated organic ether solvent. Preferably, the solvent comprises at least one or more of chain esters, chain ethers, fluorinated esters, and fluorinated ethers and at least one or more of cyclic esters, cyclic ethers, fluorinated cyclic esters, and fluorinated cyclic ethers.

[0062] The organic ester solvent includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl vinyl carbonate (EMC), methyl propyl carbonate (MPC), di-n-butyl carbonate (DBC), methyl butyl carbonate (BMC), dipropyl carbonate (DPC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), 1,4-butyrolactone (GBL), methyl ester (PA), methyl formate (MF), ethyl acetate (MA) and methyl propionate (MP), preferably one or more of diethyl carbonate (DEC), methyl vinyl carbonate (EMC) and ethylene carbonate (EC);

[0063] The fluorinated organic ester solvent includes one or more of the fluorinated compounds of the organic ester solvent, preferably one or more of fluorodiethyl carbonate (FDEC), fluoroethylene methyl carbonate (FEMC), and fluoroethylene carbonate (FEC);

[0064] The organic ether solvent includes one or more of dibutyl ether (DBE), ethylene glycol dimethyl ether (DME), dimethoxymethane (DMM), ethylene glycol diethyl ether (DEE), triethylene glycol dimethyl ether (G3), tetrahydrofuran (THF), 1,3-dioxolane (DOL) and 1,4-dioxane (1,4DX); preferably, the organic ether solvent includes one or more of ethylene glycol dimethyl ether (DME), dimethoxymethane (DMM), ethylene glycol diethyl ether (DEE), tetrahydrofuran (THF) and 1,3-dioxolane (DOL).

[0065] The fluorinated organic ether solvent includes one or more compounds of the organic ether solvent after fluorination.

[0066] The mass ratio of the fluorinated organic ester solvent and the fluorinated organic ether solvent in the electrolyte to the mass ratio of the electrolyte solvent is 10% to 50%, and can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any value between 10% and 50%. Preferably, the mass ratio of the fluorinated organic ester solvent and the fluorinated organic ether solvent in the electrolyte to the mass ratio of the electrolyte solvent is 10% to 20%.

[0067] The high voltage electrolyte also includes a lithium salt, wherein the lithium salt in the electrolyte is selected from lithium perchlorate (LiClO4 ), lithium hexafluorophosphate (LiPF 6 ) and lithium hexafluoroarsenate (LiAsF 6 ) any one or more of them.

[0068] The concentration of the lithium salt in the electrolyte may be 0.5 to 1.2 mol / L, and may be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or any value between 0.5 and 1.2 mol / L.

[0069] In the present invention, regardless of the changes in the ratio of solvent, lithium salt and additives in the high voltage electrolyte, the ion conductivity of the electrolyte measured at -30°C, 0°C and 25°C is higher than 1.5mS / cm, 4.0mS / cm and 7.0mS / cm.

[0070] The high voltage electrolyte, regardless of the change in the ratio of the solvent, the lithium salt and the additive, has a lithium ion transference number measured at 25° C. that satisfies t Li ≥0.2.

[0071] The high voltage electrolyte has a viscosity of no more than 3.0 mPa·s when measured at 25° C. regardless of changes in the ratio of the solvent, the lithium salt and the additive.

[0072] The high-voltage electrolyte provided by the present invention fully considers the high-voltage tolerance of the solvent in the lithium-rich manganese-based positive electrode material system, uses chain and cyclic fluorinated esters to improve the high-voltage antioxidant performance; uses a variety of positive and negative electrode film-forming additives to promote interface synergistic film formation, regulates the balance of organic / inorganic components of the interface solid electrolyte layer, and finely regulates the inorganic components LiF, Li 3 PO 4 , Li x PO y F and Li x BO y F z And organic composition C=O, CO, BO and LiSO 3 R z LiF is used to protect the electrode from electrolyte corrosion, Li 3 PO 4 , Li x PO y F and Li x BO y F z Consumes free hydrofluoric acid and forms a fast ion conductor layer, reducing ion diffusion resistance; in addition, organic compositions C=O, CO, BO and LiSO 3 R zThe materials have good elastic modulus and can effectively inhibit the cracking of particles and the gas production caused by repeated film-forming side reactions caused by the significant expansion and contraction of the positive and negative electrodes during the charge and discharge process. By regulating the ratio of organic / inorganic components in the electrolyte layer at the positive and negative electrode interface and characterizing and identifying the components containing F, P, B and S, a large number of DOE tests on the electrolyte system and additives can be reduced, significantly reducing costs. At the same time, the film-forming effects of each element component can be clarified, and the complicated design of electrolyte solvents and additive materials can be avoided, achieving the goal of solving complex problems with simple solutions.

[0073] The lithium-rich manganese-based positive electrode system battery of the present invention also includes a negative electrode, and the negative electrode is metallic lithium.

[0074] The lithium-rich manganese-based positive electrode system battery of the present invention further comprises a diaphragm, and the diaphragm is selected from a polypropylene diaphragm or a polyethylene diaphragm.

[0075] The lithium-rich manganese-based positive electrode system battery of the present invention also includes a positive electrode, and the positive electrode active material in the positive electrode includes one or more of a cobalt-free lithium-rich manganese-based positive electrode material and a cobalt-containing lithium-rich manganese-based positive electrode material.

[0076] In the present invention, the first charging voltage of the lithium-rich manganese-based positive electrode system battery needs to be higher than 4.55V.

[0077] In order to further understand the present invention, the high-voltage electrolyte provided by the present invention and its application in a lithium-rich manganese-based positive electrode system are described below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0078] Electrolyte configuration

[0079] The solvent, lithium salt and additive are transferred to a glove box filled with argon under sealed conditions. The solvent is dehydrated with 4A molecular sieve before use, and the lithium salt and additive are dried in a low-temperature vacuum environment. Place a clean polytetrafluoroethylene container in a controllable temperature insulation instrument, first prepare the solvent system according to a certain mass ratio, and after it is completely dissolved to form a uniform solution, cool it to room temperature; weigh it, add lithium salt and additives according to the mass ratio, and control the temperature to keep at room temperature during the entire process of addition to avoid heat generated by dissolution, which causes the lithium salt and additive to form hydrofluoric acid. After the prepared electrolyte is stable, use 4A molecular sieve for further dehydration, and add a trace amount of lithium carbonate to remove hydrofluoric acid.

[0080] Electrolyte testing

[0081] Ionic conductivity

[0082] The ionic conductivity of different components was measured using an ion conductivity meter. Before the test, a standard potassium chloride aqueous solution (298K, 0.01M KCl, σ=1.413mS / cm; 0.1M KCl, σ=12.90mS / cm) was used for calibration.

[0083] Ion migration number

[0084] The Zahner electrochemical workstation was used to measure the lithium ion migration number of the electrolyte. First, the electrochemical workstation was used to test the interface impedance R between the electrolyte and the electrode before the initial lithium symmetric battery polarization. 0 , disturbance voltage 5mV, frequency range 5MHz-10mHz. After the test is completed, the wire is short-circuited to the equilibrium potential. Using the electrochemical workstation constant potential chronoamperometry curve, apply a polarization voltage ΔV = 10mV to the battery and record the initial current I 0 And the stable current I s After the test, the impedance R between the electrolyte and the electrode after polarization is measured. s , the ion migration numbers of different components were calculated according to the Bruce and Vincent formula.

[0085]

[0086] Electrolyte viscosity

[0087] Use NDJ-9s viscometer to measure the viscosity of different electrolyte components. The electrolyte is introduced into the container configured by the instrument. Before the test, the electrolyte is placed in the required environment for 2 hours. After stabilization, the measurement is performed. The range is selected as 10mPa·s. After the test is completed, the reading is read.

[0088] Lithium-ion secondary battery

[0089] Battery production

[0090] Pole preparation: Li-rich manganese-based positive electrode material Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2, acetylene black and polyvinylidene fluoride are placed in a vacuum drying oven at 60°C for 12 hours. Take the dried material, add it to N-methylpyrrolidone as a solvent in a mass ratio of 8:1:1 and mix it thoroughly. In the dew point room, evenly apply the evenly dispersed slurry on the aluminum foil current collector. The pole piece is placed in a 55°C oven for 5 hours until the NMP is completely volatilized, and then cut into discs with a diameter of 12 mm. After weighing, it is placed in a vacuum oven at 120°C for 6 hours to completely remove the water and solvent in the pole piece. Finally, the dried pole piece is taken out and transferred to the glove box. The surface density of the prepared pole piece active material is 3-5 mg / cm 2 about.

[0091] Battery assembly: The battery was assembled in a glove box filled with argon. The button battery shell model used was R2032 (made of 304 stainless steel), the electrolyte was the electrolyte prepared in the embodiments of the present invention and the comparative example, the diaphragm was a 25um polypropylene diaphragm, and the negative electrode was a metal lithium sheet with a diameter of 16.3mm and a thickness of 500um.

[0092] Battery Test:

[0093] Chemical composition :After the battery is assembled, it is placed for more than 2 hours to allow the electrolyte to fully penetrate the inside of the electrode. Then the charge and discharge test is carried out on the Land CT 3002A (Wuhan Blue Electric) charge and discharge tester, with a capacity current density of 25mA / g, a voltage range of 2.0-4.8V, and a standard specific capacity C after 3 cycles. 0 (mAh / g).

[0094] Cycle Test : 45℃, 1.0C / 1.0C, 2.0-4.8V, 1.0C=C 0 (mAh / g).

[0095] Ratio test : 25℃, 0.1C / 0.1C, 0.2C / 0.2C, 0.3C / 0.3C, 0.5C / 0.5C, 1.0C / 1.0C, 2.0C / 2.0C, 5.0C / 5.0C, 2.0-4.8V, 1.0C=C 0 (mAh / g).

[0096] EIS AC impedance test : Zahner electrochemical workstation was used with a test frequency of 5MHz-50mHz and a voltage amplitude of 10mV.

[0097] Characterization analysis

[0098] Scanning electron microscopy (SEM): The surface morphology was characterized using a Hitachi S4800 field emission electron microscope (FE-SEM, S4800).

[0099] X-ray photoelectron spectroscopy (XPS): XPS test uses ESCALAB 250Xi photoelectron spectrometer from Thermo Fisher Scientific, and the light source is monochromatic Al Kα X-ray. The sample preparation process is as follows: disassemble the cycled battery in the glove box, take out the positive electrode, wash it three times with DMC to remove the residual electrolyte, and then place it in the glove box transition chamber to evacuate for 2 hours to remove the solvent. Use the sample transfer box made by Thermo Fisher Scientific to transfer the sample to the XPS instrument to avoid contact between the sample and the air. The data obtained from the test are fitted and quantitatively analyzed using Avantage software. The energy correction of the spectral data is to correct the peak energy value corresponding to the CC bond (conductive additive) in the C1s spectrum to 284.8eV.

[0100] Atomic force microscope (AFM): American Bruker Multimode 8 atomic force microscope, using k = 0.4N / m, f 0 =70kHz PF-TUNA conductive probe, the instrument is located in a glove box, argon atmosphere. Image acquisition area 2×2um, scan rate 0.5Hz.

[0101] Example

[0102] The following examples describe the disclosure of the present invention in more detail, and these examples are intended for illustrative purposes only, as various modifications and variations within the scope of the disclosure of the present invention will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0103] Example 1

[0104] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0105] Example 2

[0106] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0107] Example 3

[0108] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorobis(oxalyl)phosphate (LiDFBOP), 1.0 wt.% lithium difluorooxalylborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0109] Example 4

[0110] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% (trimethylsilyl) phosphite (TMSPi), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0111] Example 5

[0112] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% ethoxy (pentafluoro) cyclotriphosphazene (PFPN), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0113] Example 6

[0114] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% tetraphenylphosphine amide (TPPA), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0115] Example 7

[0116] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium difluorobis(oxalyl)phosphate (LiDFBOP), 0.5 wt.% (trimethylsilyl)phosphite (TMSPi), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0117] Example 8

[0118] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium difluorobis(oxalyl)phosphate (LiDFBOP), 0.5 wt.% tetraphenylphosphineamide (TPPA), 1.0 wt.% lithium difluorooxalylborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0119] Example 9

[0120] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6The lithium salt was stirred until completely dissolved, and then 0.5 wt.% (trimethylsilyl) phosphite (TMSPi), 0.5 wt.% tetraphenylphosphine amide (TPPA), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0121] Example 10

[0122] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium bis(oxalatoborate) (LiBOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0123] Embodiment 11

[0124] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% triethyl borate (TEB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0125] Example 12

[0126] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% tris(trimethyl)silane borate (TMSB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0127] Embodiment 13

[0128] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 0.5 wt.% lithium difluorooxalatoborate (LiDFOB), 0.5 wt.% tris(trimethyl)silaneborate (TMSB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0129] Embodiment 14

[0130] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 0.5 wt.% lithium bis(oxalatoborate) (LiBOB), 0.5 wt.% tris(trimethyl)silaneborate (TMSB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0131] Embodiment 15

[0132] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 0.5 wt.% lithium bis(oxalatoborate) (LiBOB), 0.5 wt.% triethyl borate (TEB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0133] Example 16

[0134] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), 0.5 wt.% lithium bis(fluorosulfonyl)imide (LiFSI), and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0135] Embodiment 17

[0136] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), 0.5 wt.% lithium bistrifluoromethanesulfonyl imide (LiTFSI), and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0137] Embodiment 18

[0138] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), 0.5 wt.% trifluoroacetylthiophene (TFPN), and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0139] Embodiment 19

[0140] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.25 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction of 0.25wt.% lithium bis(fluorosulfonyl)imide (LiFSI), mass fraction of 0.3wt.% 1,3-propane sultone (PS).

[0141] Embodiment 20

[0142] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.25 wt.% lithium tetrafluoroborate (LiBF 4 ), 0.25wt.% lithium bistrifluoromethanesulfonyl imide (LiTFSI), and 0.3wt.% 1,3-propane sultone (PS).

[0143] Embodiment 21

[0144] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.25 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.25wt.% trifluoroacetylthiophene (TFPN), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0145] Embodiment 22

[0146] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% ethylene sulfite (ES).

[0147] Embodiment 23

[0148] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4), mass fraction 0.3wt.% vinyl sulfate (DTD).

[0149] Embodiment 24

[0150] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% methylene methanedisulfonate (MMDS).

[0151] Embodiment 25

[0152] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% dimethyl sulfoxide (DMSO).

[0153] Embodiment 26

[0154] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.15wt.% 1,3-propane sultone (PS), mass fraction 0.15wt.% diethyl sulfate (DTD).

[0155] Embodiment 27

[0156] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.15wt.% 1,3-propane sultone (PS), mass fraction 0.15wt.% methylene methane disulfonate (MMDS).

[0157] Embodiment 28

[0158] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.15wt.% 1,3-propane sultone (PS), mass fraction 0.15wt.% dimethyl sulfoxide (DMSO).

[0159] Embodiment 29

[0160] Fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0161] Embodiment 30

[0162] Fluoroethylene carbonate (FEC) and diethyl carbonate (DEC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0163] Embodiment 31

[0164] Fluoroethylene carbonate (FEC), diethyl carbonate (DEC) and 1,3-dioxolane (DOL) were mixed in a mass ratio of 2:7:1 and 1.2 mol / L LiPF was added. 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0165] Comparative Example 1

[0166] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 Lithium salt, stir until completely dissolved.

[0167] Comparative Example 2

[0168] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly in a mass ratio of 3:7, and 1.2 mol / L LiPF 6 Lithium salt, stir until completely dissolved.

[0169] Comparative Example 3

[0170] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) is added.

[0171] Comparative Example 4

[0172] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) was added.

[0173] Comparative Example 5

[0174] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0175] Comparative Example 6

[0176] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 0.3wt.% 1,3-propane sultone (PS) is added.

[0177] Comparative Example 7

[0178] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) are added.

[0179] Comparative Example 8

[0180] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0181] Comparative Example 9

[0182] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0183] Comparative Example 10

[0184] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0185] Comparative Example 11

[0186] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0187] Comparative Example 12

[0188] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0189] Comparative Example 13

[0190] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0191] Comparative Example 14

[0192] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0193] Comparative Example 15

[0194] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0195] Comparative Example 16

[0196] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0197] Comparative Example 17

[0198] Ethylene carbonate (EC) and vinyl methyl carbonate (EMC) were mixed evenly at a mass ratio of 2:8, and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0199] Comparative Example 18

[0200] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 Lithium salt, stir until completely dissolved.

[0201] Comparative Example 19

[0202] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 3:7 and 1.2 mol / L LiPF 6 Lithium salt, stir until completely dissolved.

[0203] Comparative Example 20

[0204] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) is added.

[0205] Comparative Example 21

[0206] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) was added.

[0207] Comparative Example 22

[0208] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0209] Comparative Example 23

[0210] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 0.3wt.% 1,3-propane sultone (PS) is added.

[0211] Comparative Example 24

[0212] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) are added.

[0213] Comparative Example 25

[0214] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0215] Comparative Example 26

[0216] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0217] Comparative Example 27

[0218] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0219] Comparative Example 28

[0220] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt is stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.3 wt.% 1,3-propane sultone (PS) are added.

[0221] Comparative Example 29

[0222] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0223] Comparative Example 30

[0224] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP), 1.0 wt.% lithium difluorooxalatoborate (LiDFOB), and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ).

[0225] Comparative Example 31

[0226] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorophosphate (LiDFP) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0227] Comparative Example 32

[0228] Fluoroethylene carbonate (FEC) and methyl ethylene carbonate (EMC) were mixed in a mass ratio of 2:8 and 1.2 mol / L LiPF 6 The lithium salt was stirred until completely dissolved, and then 1.0 wt.% lithium difluorooxalatoborate (LiDFOB) and 0.5 wt.% lithium tetrafluoroborate (LiBF 4 ), mass fraction 0.3wt.% 1,3-propane sultone (PS).

[0229] The physical properties of the electrolytes configured in the above-mentioned embodiments and comparative examples are summarized in Table 1.

[0230] Table 1

[0231]

[0232]

[0233] It can be seen from Table 1 that in the above embodiments, the use of lithium salt and solvent in the electrolyte has little effect on the performance of the electrolyte.

[0234] After the electrolyte solutions of the above-listed embodiments and comparative examples were prepared into batteries, the performance of the batteries was summarized as shown in Table 2.

[0235] Table 2

[0236]

[0237]

[0238]

[0239] From the data results in Table 2, it can be seen that in Comparative Examples 1 to 2, when the electrolyte solvent is an organic ester solvent and no additives are added, the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side of the battery to the inorganic component of the electrolyte interface layer is higher than 1, and the surface fluctuation Fluc. detected by AFM on the negative electrode side is significantly higher than 200nm. Therefore, the high temperature cycle performance of the battery is poor, 200th The cycle capacity retention rates were only 14.26% and 16.70%.

[0240] In Comparative Examples 3 to 17, when the electrolyte solvent is an organic ester solvent, even after the additive is added, the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side of the battery to the inorganic component of the electrolyte interface layer is higher than 1, and the surface fluctuation Fluc. detected by AFM on the negative electrode side is significantly higher than 200 nm.

[0241] Therefore, the high temperature cycle performance of the battery is poor, but due to the addition of additives, compared with the battery performance of Comparative Examples 1 to 2, 200 th The cycle capacity retention rate has been improved to a certain extent.

[0242] In Comparative Examples 18 to 19, when part of the ester solvent of the electrolyte was replaced by a fluorinated carbonate and no additive was added, the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side of the obtained battery to the inorganic component of the electrolyte interface layer was less than 0.6, and the surface fluctuation Fluc. detected by AFM on the negative electrode side was significantly higher than 200 nm. Therefore, the high temperature cycle performance of the battery was poor, 200 th The cycle capacity retention rates were only 33.08% and 40.56%.

[0243] In Comparative Examples 20 to 32, when part of the ester solvent in the electrolyte is replaced by a fluorinated carbonate, but the elements contained in the added additives include 1 to 3 of the elements fluorine, boron, phosphorus and sulfur, the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side of the battery to the inorganic component of the electrolyte interface layer does not satisfy (0.6 to 1): 1, or does not satisfy the surface undulation difference Fluc. ≤ 200 nm detected by AFM on the negative electrode side. Even if the above two indicators are met, the high temperature cycle performance of the obtained battery is still low because the element types of the additives do not contain fluorine, boron, phosphorus and sulfur at the same time.

[0244] It can be seen from Example 1 that when part of the ester solvent is replaced by fluorinated carbonate and a small amount of fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds and sulfide-containing additives are added, the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side of the battery to the inorganic component of the electrolyte interface layer does not meet (0.6-1):1, but the surface undulation Fluc. detected by AFM on the negative electrode side is greater than 200nm, which will affect the high temperature cycle performance of the battery to a certain extent.

[0245] It can be seen from Examples 2 to 31 that when part of the ester solvent is replaced by fluorinated carbonate, and a small amount of fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds, and sulfide-containing additives are added, not only does it not significantly reduce the ionic conductivity of the electrolyte at room temperature and low temperature, the lithium ion migration number, and increase the viscosity of the electrolyte, but also uses fluorinated solvents and fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds, and sulfide-containing additives to construct an effective coating layer at the electrode interface, and controls the mass ratio of the organic component of the electrolyte interface layer on the positive electrode side to the inorganic component of the electrolyte interface layer to be (0.6 to 1): 1, and the surface undulation Fluc. detected by AFM on the negative electrode side is ≤200nm, which significantly improves the high-temperature cycle stability of the lithium-rich manganese-based positive electrode in a high voltage (≥4.55V) system. Especially in Examples 7, 15, 19, 25, and 28, the 200 th The cycle capacity retention rate is >90%. Furthermore, when the surface fluctuation Fluc. detected by AFM on the negative electrode side is ≤100nm, the 200 th The cycle capacity retention rate is >92%.

[0246] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Application of a high voltage electrolyte in a lithium-rich manganese-based positive electrode system battery, characterized in that: The lithium-rich manganese-based positive electrode system battery comprises a positive electrode, a negative electrode, a high-voltage electrolyte and a separator; The high voltage electrolyte comprises a solvent, a lithium salt and an additive, wherein the additive comprises fluorine, boron, phosphorus and sulfur; After the lithium-rich manganese-based positive electrode system battery is charged and discharged for the first time at a high voltage of more than 4.55V, the mass ratio of the organic component of the electrolyte interface layer to the inorganic component of the electrolyte interface layer is (0.6-1):

1.

2. The use according to claim 1, characterized in that: The organic component of the electrolyte interface layer includes a compound containing one or more bonds of C=O, CO, BO and one or more of LiSO3R, where R is one or more of an aromatic group or a hydrocarbon group; The inorganic components of the electrolyte interface layer include POF, LiF, Li x BO y F z 、LiPF6,Li3PO4、Li x PO y F z and LiP x F y One or more of x BO y In F, x, y and z satisfy x+3-2y-z=0; in Li x PO y F z In LiP, x, y and z satisfy x+5-2y-z=0; x F y In Li, x and y satisfy 1+5x-y=0; x BO y F, Li x PO y F z and LiP x F y In this equation, x, y, and z are any natural real numbers that satisfy the law of conservation of charge.

3. The use according to claim 1, characterized in that: The additives include fluorine-containing compounds, boron-containing compounds, phosphorus-containing compounds and sulfur-containing compounds; The fluorine-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the fluorine-containing compound includes one or more compounds containing one or more bonds of FO, FP, and FB; The boron-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the boron-containing compound includes one or more compounds containing one or more bonds among BO, BP, and BF; The phosphorus-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the phosphorus-containing compound includes one or more compounds containing one or more bonds of PO, PB, and PF; The sulfur-containing compound is an organic or inorganic substance soluble in the solvent. Preferably, the sulfur-containing compound includes one or more compounds containing one or more bonds of SO, SC, and SS.

4. The use according to claim 1, characterized in that: The fluorine-containing compound includes one or more of lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalatoborate (LiDFOB), lithium bis(fluorosulfonyl imide) (LiFSI), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium difluorophosphate (LiDFP), methyl difluoroacetate (MFA), tris(pentafluorophenyl)borane (TPFPB), tris(2,2,2-trifluoroethyl)phosphite (TTFP), ethoxy-pentafluoro-cyclotriphosphazene (PFN), fluorinated ethyl phosphate (FEP), fluorinated phosphate tris(2,2,2-trifluoroethyl) phosphate (TFP), fluorosulfonyl isocyanate (FI), 1,2-bis(difluoromethylsilyl)ethane (FSE), 2,3-difluorotoluene (DFT) and trifluoroacetylthiophene (TFPN); And / or, the boron-containing compound includes one or more of lithium tetrafluoroborate (LiBF4), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), 4-benzonitrile trimethylborate (LBTB), trimethyl borate (TMB), triethyl borate (TEB), tripropyl borate (TPB), tris(trimethyl)silaneborate (TMSB), tris(2-nitrileethyl)borate (TCEB), tris(2,2,2-trifluoroethyl)borate (TTFEB), 3-thiopheneboric acid (TB), pyridine-boron trifluoride (PBF), methylboronic acid methyliminodiacetate (ADM) and tris(pentafluorophenyl)borane (TPFPB); And / or, the phosphorus-containing compound of the electrolyte additive includes one or more of lithium difluorophosphate (LiDFP), lithium difluorobisoxalate phosphate (LiDFBOP), lithium tetrafluoro(fluoropropylene glycol) phosphate (LFMP), (trimethylsilyl) phosphite (TMSPi), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), tetraphenylphosphine amide (TPPA), 1,2-bis(diphenylphosphino)ethane (DPPE), 1-propylphosphoric acid cyclic anhydride (PACA), tris(trimethylsilyl) phosphate (TTSP), triethyl phosphite (TEP), tripropargyl phosphate (TPP), tris(2,2,2-trifluoroethyl) phosphite (TTFP), dimethyl methylphosphonate (DMMP), diethyl phenylphosphonate (DPP) and bis(2,2,2-trifluoroethyl) methylphosphonate (TFMP); And / or, the sulfur-containing compound includes one or more of 1,3-propane sultone (PS), vinyl sulfite (ES), dimethyl sulfite (DMS), diethyl sulfite (DES), propylene sulfite (TMS), vinyl vinyl sulfite (VES), vinyl sulfate (DTD), 1,3-propylene sultone (PST), 1,3-propylene glycol cyclic sulfate (PCS), trifluoromethylphenyl sulfide (PTS), dimethanesulfonylmethane (DMSM), methylene methane disulfonate (MMDS), 1,1-sulfonyldiimidazole (SDM), 3-(phenylsulfonyl)propionitrile (PSPN), dimethyl sulfoxide (DMSO), sulfolane (SL), and 1,2Λ6-oxathiolane-2,2,5-trione (SPA).

5. The use according to claim 1, characterized in that: After the lithium-rich manganese-based positive electrode system battery has been subjected to 200 charge and discharge cycles at 45°C and above 4.55V, the negative electrode side is scanned by SEM and AFM. The SEM morphology of the negative electrode surface is smooth and free of cracks, and there is no obvious particle attachment; the AFM detection of the negative electrode surface fluctuation Fluc. ≤200nm.

6. The use according to claim 1, characterized in that: The solvent includes one or more of an organic ester solvent, a fluorinated organic ester solvent, an organic ether solvent and a fluorinated organic ether solvent.

7. The use according to claim 5, characterized in that: The organic ester solvent includes one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl vinyl carbonate (EMC), methyl propyl carbonate (MPC), di-n-butyl carbonate (DBC), methyl butyl carbonate (BMC), dipropyl carbonate (DPC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), 1,4-butyrolactone (GBL), methyl ester (PA), methyl formate (MF), ethyl acetate (MA) and methyl propionate (MP); The fluorinated organic ester solvent includes one or more compounds of the organic ester solvent after fluorination; The organic ether solvent includes one or more of dibutyl ether (DBE), ethylene glycol dimethyl ether (DME), dimethoxymethane (DMM), ethylene glycol diethyl ether (DEE), triethylene glycol dimethyl ether (G3), tetrahydrofuran (THF), 1,3-dioxolane (DOL) and 1,4-dioxane (1,4DX); The fluorinated organic ether solvent includes one or more compounds of the organic ether solvent after fluorination.

8. The use according to claim 1, characterized in that: In the electrolyte solvent, the mass ratio of the fluorinated organic ester solvent and the fluorinated organic ether solvent to the mass ratio of the electrolyte solvent is higher than 10wt.%, In the electrolyte, the content of the additive is 0.1wt% to 5wt%.

9. The use according to claim 1, characterized in that: The negative electrode is metallic lithium, the electrolyte is the electrolyte according to any one of claims 1 to 8, and the separator is selected from a polypropylene separator or a polyethylene separator.

10. The use according to claim 1, characterized in that: The first charging voltage of the lithium-rich manganese-based positive electrode system battery needs to be higher than 4.55V.

Images