In-situ generated electrolyte additive, and preparation method and application thereof

Abstract

The present application relates to an in-situ generated electrolyte additive and its preparation method and application, the additive is a Lewis acid-base complex multifunctional additive; the Lewis acid-base complex multifunctional additive is prepared by adding Lewis acid and Lewis base in conventional electrolyte, and then by the Lewis acid-base coordination reaction between Lewis acid and Lewis base; the additive can be in-situ generated in electrolyte, and has the multifunction of widening the electrochemical window of electrolyte, flame retardation, inhibiting the decomposition and hydrolysis of electrolyte salt, removing harmful impurities of electrolyte, stabilizing electrode material and electrolyte interface and the like.The obtained multifunctional electrolyte containing the additive can be used to improve the working voltage, energy density, power density, cycle life and safety of electrochemical energy storage device, and is easy to popularize and apply.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new materials, new energy and electrochemical energy storage, and particularly relates to an in-situ generated electrolyte additive, a preparation method and application thereof, and especially relates to a preparation method and application of a multifunctional electrolyte additive of Lewis acid-base complex generated in-situ in an electrolyte through Lewis acid-base coordination reaction and a multifunctional electrolyte containing the additive. BACKGROUND

[0002] With the rapid development of global economy, the problems of resource depletion and environmental pollution are becoming increasingly serious, and it has become a consensus to develop new renewable energy to replace fossil energy such as oil, coal and natural gas. At the same time, the rapid development of new energy technology urgently needs high-performance energy storage technology to match. Therefore, as an important branch of new energy storage technology, improving the performance of electrochemical energy storage devices (such as lithium metal batteries, lithium ion batteries and supercapacitors) has been an important research direction in the industry of new materials and new energy, which has brought huge investment from all over the world to research and develop a new generation of high-performance electrochemical energy storage devices with high working voltage, high energy density, high power density, long cycle life and high safety.

[0003] Electrolyte is one of the core components of electrochemical energy storage devices. The electrolyte of the existing electrochemical energy storage devices is mostly an organic conventional electrolyte based on carbonate solvents and lithium hexafluorophosphate (LiPF6) electrolyte salts. Some common problems of these electrolytes directly affect the performance of electrochemical energy storage devices. For example, the narrow electrochemical window of the electrolyte solvent limits the working voltage of the device, thereby limiting the energy density and power density of the device; the flammability of the electrolyte solvent determines the safety hazard of the device; the decomposition and hydrolysis products (such as HF and P-O-F series products) of the electrolyte electrolyte salt cause the corrosion of the electrode material, resulting in poor cycle life and safety of the device; the negative reaction of trace harmful impurities (such as H2O and O2) in the electrolyte with the electrode material leads to poor cycle life and safety of the device.

[0004] Introducing additives into conventional commercial electrolyte is a simple, economical and easy-to-operate method to solve the above-mentioned electrolyte problems. To meet the needs of high-performance electrochemical energy storage devices, the development of new multifunctional electrolyte additives has become a hot topic in the field of energy storage research. Chinese patent CN105609875B discloses a kind of acrylic sulfate anhydride derivative additive and carbonate and LiPF6 high-voltage electrolyte (4.5V or more) containing the additive (4.5V or more), matched with high-voltage positive electrode material, the working voltage and energy density of the obtained lithium ion battery are improved. At the same time, the additive helps to form a stable solid electrolyte interface film (SEI film), thereby improving the cycle performance of lithium ion battery. Chinese patent CN104022309A discloses a fluorine alkoxy phosphate flame retardant additive that can be used in lithium ion batteries. The additive can effectively inhibit the combustion of carbonate and LiPF6 electrolyte. Ma et al. reported the introduction of ethylene sulfite (ES) as an additive in propylene carbonate (PC) based electrolyte, which forms a stable and dense SEI film on the surface of soft carbon negative electrode, thereby effectively reducing the internal resistance and improving the rate performance and low temperature performance of the obtained lithium ion supercapacitor (P.L. Wang, X.Z. Sun, Y.W. Ma, Additives to propylene carbonate-based electrolytes for lithium-ion capacitors, Rare Metals, 41 (2022) 1304-1313). Song et al. reported that the addition of tris(trimethylsilyl) phosphite (TMSP) additive can remove HF impurities in carbonate and LiPF6 electrolyte, and can also form positive electrode electrolyte interface film (CEI film) and SEI film on the surface of lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4, LNMO) positive electrode and graphite (Gr) negative electrode, respectively, to inhibit the negative reaction of electrolyte and electrode interface, and improve the cycle stability of the obtained lithium ion battery (Y.-M. Song, J.-G. Han, S. Park, K.T. Lee, N.-S. Choi, A multifunctional phosphite-containing electrolyte for 5 V-class LiNi 0.5 Mn 1.5O4 cathodes with superior electrochemical performance, Journal of Materials Chemistry A, 2 (2014) 9506-9513). Zhang et al. introduced fluoroethylene carbonate (FEC) as an additive into 1 M LiPF6 and ethylene carbonate (EC): diethyl carbonate (DEC) (1:1 by volume) electrolyte to fabricate lithium metal batteries based on metal lithium anode and LiNi 0.5 Co 0.2 Mn 0.3 O2 cathode. Due to the formation of a dense SEI film rich in LiF on the lithium anode by FEC, the growth of lithium dendrites was effectively inhibited, and thus the stability and cycle life of the resulting lithium metal batteries were improved (X.-Q. Zhang, X.-B. Cheng, X. Chen, C. Yan, Q. Zhang, Fluoroethylene Carbonate Additives to Render Uniform Li Deposits in Lithium Metal Batteries, Advanced Functional Materials, 27 (2017) 1605989). Zheng et al. synthesized a fluorine-containing cyclic phosphoric acid tris(2,2,2-trifluoroethyl) ester (TFEP) by special design and used it as an additive for lithium metal batteries based on cyclic carbonate and LiPF6 electrolyte and metal lithium anode and LNMO cathode. Due to the flame-retardant property of TFEP and its multifunctional effect of generating CEI and SEI protective films on the cathode and anode, respectively, the resulting lithium metal batteries exhibited excellent electrochemical performance in a high voltage range of 3.5-4.9 V (Q. Zheng, Y. Yamada, R. Shang, S. Ko, Y.-Y. Lee, K. Kim, E. Nakamura, A. Yamada, A cyclic phosphate-based battery electrolyte for high voltage and safe operation, Nature Energy, 5 (2020) 291-298).

[0005] However, the prior art still has the following disadvantages:

[0006] (1) Most of the currently reported electrolyte additives have single performance (lack of multifunctionality), and cannot comprehensively solve the problems faced by the electrolyte for electrochemical energy storage devices;

[0007] (2) The pre-synthesized additive needs to be added to a certain electrolyte to prepare the desired electrolyte containing the additive;

[0008] (3) Although some multifunctional additives can be prepared by special design, the synthesis process is complex, high cost and time-consuming, which is not conducive to large-scale production and application.

[0009] Therefore, in order to research and develop a new generation of high-performance electrochemical energy storage devices, it is urgent to develop multifunctional additives that can be generated in situ in electrolyte and have as many as possible the properties of expanding the electrochemical window of electrolyte, flame retardation, inhibiting the decomposition and hydrolysis of electrolyte salt, removing harmful impurities in electrolyte, stabilizing the interface between electrode material and electrolyte, etc. And multifunctional electrolyte containing the additive. SUMMARY

[0010] In view of the common problems of the electrolyte for the current electrochemical energy storage devices:

[0011] The first object of the present application is to provide a method for preparing a multifunctional additive generated in situ and a multifunctional electrolyte containing the additive. The additive can be generated in situ in the electrolyte and has the multifunction of expanding the electrochemical window of the electrolyte, flame retardation, inhibiting the decomposition and hydrolysis of the electrolyte salt, removing harmful impurities in the electrolyte, stabilizing the interface between the electrode material and the electrolyte, etc. The multifunctional electrolyte containing the additive obtained can be used to improve the working voltage, energy density, power density, cycle life and safety of the electrochemical energy storage device;

[0012] The second object of the present application is to provide a multifunctional electrolyte containing a multifunctional additive generated in situ for electrochemical energy storage devices (including lithium metal batteries, lithium ion batteries, sodium metal batteries, sodium ion batteries, potassium metal batteries, potassium ion batteries, supercapacitors, etc.).

[0013] To achieve the above objects, the technical solutions adopted by the present application are as follows:

[0014] The first aspect of the present application provides an electrolyte additive generated in situ, and the additive is a Lewis acid-base complex multifunctional additive; the Lewis acid-base complex multifunctional additive is prepared by adding a Lewis acid and a Lewis base in a conventional electrolyte, and then a Lewis acid-base coordination reaction occurs between the Lewis acid and the Lewis base;

[0015] The Lewis acid is at least one of boron trifluoride, iron trichloride, aluminum trichloride, fluoroethylene carbonate and difluoroethylene carbonate;

[0016] The Lewis base is at least one of diphenyldimethoxysilane, hexamethyldisilazane, 1,3-bis(1-isocyanato-1-methylethyl)benzene, tris(trimethylsilyl)phosphite, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl)phosphite, pyridine, diethyl ether, hexakis(2,2,2-trifluoroethoxy)cyclotriphosphazene, triethanolamine, and lithium 4,5-dicyano-2-(trifluoromethyl)isopyrazole.

[0017] Further, preferably, the Lewis acid is added in an amount of 0.1-20% of the mass of the conventional electrolyte; and the Lewis base is added in an amount of 0.1-20% of the mass of the conventional electrolyte.

[0018] Further, preferably, the electrolyte salt in the conventional electrolyte is a lithium salt, a sodium salt, or a potassium salt; and the electrolyte salt is at least one of a perchlorate salt, a hexafluorophosphate salt, a bisoxalate borate salt, a tetrafluoroborate salt, a difluoro oxalate borate salt, a bis(trifluoromethylsulfonyl)imide salt, a bis(fluorosulfonyl)imide salt, a difluorophosphate salt, and a difluoro oxalate phosphate salt.

[0019] The second aspect of the present application provides a preparation method of the above-mentioned in-situ generated electrolyte additive, in which a Lewis acid and a Lewis base are added into a conventional electrolyte, and then a Lewis acid-base coordination reaction between the Lewis acid and the Lewis base is carried out to obtain the electrolyte additive.

[0020] Further, preferably, the Lewis acid and the Lewis base are added into the conventional electrolyte under an inert gas atmosphere to carry out the Lewis acid-base coordination reaction.

[0021] Further, preferably, the inert gas atmosphere is specifically an atmosphere with oxygen <1 ppm and moisture <1 ppm.

[0022] Further, preferably, the Lewis acid-base coordination reaction is carried out for 12-36 hours.

[0023] The third aspect of the present application provides an electrolyte containing the above-mentioned in-situ generated electrolyte additive.

[0024] The fourth aspect of the present application provides an electrochemical energy storage device containing the above-mentioned electrolyte containing the in-situ generated electrolyte additive.

[0025] Further, preferably, the electrochemical energy storage device comprises a shell, a positive electrode and a negative electrode installed in the shell, and a separator; the separator is arranged between the positive electrode and the negative electrode; and the electrolyte containing the in-situ generated electrolyte additive is filled in the gap between the positive electrode and the separator and in the gap between the negative electrode and the separator.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] The present application aims at the following shortcomings of the current electrolyte additives: single function, unable to fully meet the requirements of high-performance electrochemical energy storage devices; complex preparation process of the additives and the electrolyte containing the additives, high cost, time-consuming, hidden safety hazards, and not conducive to large-scale production and application; and provides a scheme with simple preparation process, easy operation, low cost, rapidity, no side reaction, no pollution, and good safety, and the obtained Lewis acid-base complex additive and the electrolyte containing the additive have multifunction and are easy to realize large-scale industrial production and wide application.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] 1. The Lewis acid-base complex multifunctional additive of the present application is generated in situ in the electrolyte through Lewis acid-base coordination reaction, and the Lewis acid-base coordination reaction can be carried out at room temperature and normal pressure, so that the preparation process is simple, easy to operate, low in cost, rapid, free of side reaction, free of pollution, and good in safety, and special reaction equipment (such as a reaction kettle) and reaction conditions (such as high temperature and high pressure) are not required.

[0030] 2. After the Lewis acid-base complex multifunctional additive of the present application is generated in situ in the electrolyte, the obtained electrolyte containing the additive can be immediately used for the assembly of electrochemical energy storage devices, and no additional electrolyte preparation process is required.

[0031] 3. The Lewis acid-base complex multifunctional additive of the present application retains the properties of its constituent components (i.e., Lewis acid and / or Lewis base), and its function can be regulated by selecting different Lewis acid and / or Lewis base.

[0032] 4. The Lewis acid-base complex multifunctional additive of the present application has the multifunction of widening the electrochemical window of the electrolyte, flame retardation, inhibiting the decomposition and hydrolysis of the electrolyte salt, removing harmful impurities in the electrolyte, and stabilizing the interface between the electrode material and the electrolyte, and can be used to comprehensively improve the performance of electrochemical energy storage devices.

[0033] 5. The multifunctional electrolyte containing the Lewis acid-base complex multifunctional additive of the present application has universality and can be widely used for preparing a series of electrochemical energy storage devices (including lithium metal batteries, lithium ion batteries, sodium metal batteries, sodium ion batteries, potassium metal batteries, potassium ion batteries, supercapacitors, etc.). BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is the F NMR chart of the electrolyte of Comparative Example 1 and Example 1 31 P NMR chart

[0035] Figure 2 is the F NMR chart of the electrolyte of Comparative Example 1 and Example 1 19 F NMR chart

[0036] Figure 3 is a negative CV test plot of the electrolyte of Comparative Example 2, Example 2; wherein a is the first cycle of negative CV, b is the fifth cycle of negative CV;

[0037] Figure 4 is a positive CV test plot of the electrolyte of Comparative Example 2, Example 2; wherein a is the first cycle of positive CV, b is the fifth cycle of positive CV;

[0038] Figure 5 is an EIS plot of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3 after 0.1 C activation;

[0039] Figure 6 is a 1 C charge-discharge cycling test plot of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3;

[0040] Figure 7 is a surface SEM plot of fresh Li anode and Li anode after 1 C charge-discharge cycling for 200 cycles of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3; wherein a is fresh Li anode, b is Li anode after cycling in conventional electrolyte; c is Li anode after cycling in TMSP:FEC electrolyte;

[0041] Figure 8 is a cross-section SEM plot of fresh Li anode and Li anode after 1 C charge-discharge cycling for 200 cycles of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3; wherein a is fresh Li anode, b is Li anode after cycling in conventional electrolyte; c is Li anode after cycling in TMSP:FEC electrolyte;

[0042] Figure 9 is a surface SEM plot of fresh LNMO cathode and LNMO cathode after 1 C charge-discharge cycling for 200 cycles of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3; wherein a is fresh LNMO cathode, b is LNMO cathode after cycling in conventional electrolyte; c is LNMO cathode after cycling in TMSP:FEC electrolyte;

[0043] Figure 10 is a TEM plot of fresh LNMO cathode and LNMO cathode after 1 C charge-discharge cycling for 200 cycles of LNMO / / Li lithium metal battery of Comparative Example 3, Example 3; wherein a is fresh LNMO cathode, b is LNMO cathode after cycling in conventional electrolyte; c is LNMO cathode after cycling in TMSP:FEC electrolyte;

[0044] Figure 11The images show the EIS diagrams of the NCM811 / / Li lithium metal batteries after activation at 0.1 C for Comparative Example 4 and Example 4.

[0045] Figure 12 The graphs show the 1C charge-discharge cycle test results of the NCM811 / / Li lithium metal batteries in Comparative Example 4 and Example 4.

[0046] Figure 13 The images show the EIS diagrams of the LFP / / Li lithium metal batteries after 0.1 C activation in Comparative Example 5 and Example 5.

[0047] Figure 14 The graphs show the 1C charge-discharge cycle test results of the LFP / / Li lithium metal batteries in Comparative Example 5 and Example 5.

[0048] Figure 15 The images show the EIS diagrams of LNMO / / Gr lithium-ion batteries after 0.1 C activation in Comparative Example 6 and Example 6.

[0049] Figure 16 The graphs show the 1C charge-discharge cycle test results of the LNMO / / Gr lithium-ion batteries in Comparative Example 6 and Example 6.

[0050] Figure 17 The images show the EIS diagrams of the LNMO / / AC lithium-ion supercapacitors of Comparative Example 7 and Example 7 after activation at 0.5 C.

[0051] Figure 18 This is a 10 C charge-discharge cycle test diagram of the LNMO / / AC lithium-ion supercapacitors of Comparative Example 7 and Example 7. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the embodiments.

[0053] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the field or according to the product instructions. Materials or equipment whose manufacturers are not specified are all conventional products that can be obtained by purchase.

[0054] The present application in-situ prepares Lewis acid-base complex multifunctional additives and multifunctional electrolytes containing the additives through Lewis acid-base coordination reactions in electrolytes. The multifunctional electrolyte containing Lewis acid-base complex multifunctional additives is composed of a conventional electrolyte and Lewis acid-base complex additives. The conventional electrolyte is composed of organic solvents and electrolyte salts; the Lewis acid-base complex additives are obtained through Lewis acid-base coordination reactions between Lewis acids and Lewis bases in the conventional electrolyte. The specific preparation steps are as follows:

[0055] 1. Preparation of a conventional electrolyte: under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of electrolyte salt is added to a selected organic solvent, mixed uniformly, and left for 12-36 h to obtain a conventional electrolyte.

[0056] 2. Preparation of Lewis acid-base complex additives and multifunctional electrolytes containing the additives: under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, selected Lewis acids and Lewis bases are added to the obtained conventional electrolyte, and left for 12-36 h to obtain Lewis acid-base complex additives and multifunctional electrolytes containing the additives.

[0057] The organic solvent in the conventional electrolyte is at least one of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), propylene carbonate (PC), fluoroethylene carbonate (FEC), fluoropropylene carbonate (TFPC), γ-butyrolactone (GBL), γ-valerolactone (GVL), N,N-dimethylformamide (DMF), acetonitrile (AN), and fluoroacetonitrile (FAN).

[0058] The concentration of the electrolyte salt in the conventional electrolyte is 0.1-10 mol·L -1 .

[0059] For lithium metal batteries and lithium ion batteries, the electrolyte salt is at least one of lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium bis(oxalato)borate (LiBOB), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiODFB), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluorophosphate (LiPO2F2), and lithium difluoro(oxalato)phosphate (LiODFP).

[0060] For sodium metal batteries and sodium ion batteries, the electrolyte salt is at least one of sodium perchlorate (NaClO4), sodium hexafluorophosphate (NaPF6), sodium bis(oxalato)borate (NaBOB), sodium tetrafluoroborate (NaBF4), sodium difluoro(oxalato)borate (NaODFB), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium bis(fluorosulfonyl)imide (NaFSI), sodium difluorophosphate (NaPO2F2), sodium difluoro(oxalato)phosphate (NaODFP);

[0061] For potassium metal batteries and potassium ion batteries, the electrolyte salt is at least one of potassium perchlorate (KClO4), potassium hexafluorophosphate (KPF6), potassium bis(oxalato)borate (KBOB), potassium tetrafluoroborate (KBF4), potassium difluoro(oxalato)borate (KODFB), potassium bis(trifluoromethylsulfonyl)imide (KTFSI), potassium bis(fluorosulfonyl)imide (KFSI), potassium difluorophosphate (KPO2F2), potassium difluoro(oxalato)phosphate (KODFP).

[0062] The Lewis acid content in the multifunctional electrolyte containing Lewis acid-base complex additive is 0.1-20% by mass, and the Lewis acid is at least one of boron trifluoride (BF3), iron trichloride (FeCl3), aluminum trichloride (AlCl3), fluoroethylene carbonate (FEC), and difluoroethylene carbonate (DFEC).

[0063] The Lewis base content in the multifunctional electrolyte containing Lewis acid-base complex additive is 0.1-20% by mass, and the Lewis base is at least one of a substance having a -Si-N structure, a substance having a -N=C=O structure, or a phosphite. Specifically, the Lewis base is at least one of diphenyldimethoxysilane (DPDMS), hexamethyldisilazane (HMDS), 1,3-bis(1-isocyanato-1-methylethyl)benzene, tris(trimethylsilyl)phosphite (TMSP), trimethylphosphite (TMP), triphenylphosphite (TPPi), tris(2,2,2-trifluoroethyl)phosphite (TTFP), pyridine (C5H5N), diethyl ether (C2H5OC2H5), hexakis(2,2,2-trifluoroethoxy)cyclotriphosphazene (HFEPN), triethanolamine (TEA), and lithium 4,5-dicyano-2-(trifluoromethyl)isopyrazole (LiTDI).

[0064] The multifunctional electrolyte containing the Lewis acid-base complex multifunctional additive is also used in the preparation of electrochemical energy storage devices, including lithium metal batteries, lithium ion batteries, sodium metal batteries, sodium ion batteries, potassium metal batteries, potassium ion batteries, supercapacitors, and the like.

[0065] The construction of the electrochemical energy storage device includes a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, an electrolyte filled in the interstice of the positive electrode, the negative electrode and the separator, and a shell, wherein the electrolyte is the multifunctional electrolyte containing the Lewis acid-base complex multifunctional additive. The specific preparation steps are as follows:

[0066] 1. According to the requirements of different electrochemical energy storage devices for electrode sheets, the corresponding positive electrode and negative electrode are prepared.

[0067] 2. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, the above-mentioned positive electrode, negative electrode, separator and multifunctional electrolyte containing Lewis acid-base complex multifunctional additive are packaged to obtain an electrochemical energy storage device.

[0068] The positive electrode of the electrochemical energy storage device is any one of the corresponding positive electrodes of the existing electrochemical energy storage devices (lithium metal battery, lithium ion battery, sodium metal battery, sodium ion battery, potassium metal battery, potassium ion battery or super capacitor).

[0069] The negative electrode of the electrochemical energy storage device is any one of the corresponding negative electrodes of the existing electrochemical energy storage devices (lithium metal battery, lithium ion battery, sodium metal battery, sodium ion battery, potassium metal battery, potassium ion battery or super capacitor).

[0070] The separator of the electrochemical energy storage device is at least one of polypropylene porous film, polyethylene porous film, polypropylene and polyethylene composite porous film, cellulose acetate porous film, glass fiber porous film, nylon and asbestos paper.

[0071] The packaging method of the electrochemical energy storage device is any one of button type, cylindrical type, square type and special-shaped type.

[0072] The packaging shell of the electrochemical energy storage device is any one of steel shell, plastic shell, aluminum shell and aluminum plastic film.

[0073] The present application will be further described in conjunction with the accompanying drawings and examples, but in no way limits the present application, any change or improvement based on the teaching of the present application shall fall within the protection scope of the present application.

[0074] Preparation and physical properties of Comparative Example 1: conventional electrolyte

[0075] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of LiPF6 was added into the organic solvent of EC / DMC / EMC (1:1:1 by volume ratio), mixed uniformly, and stood for 24 hours to obtain the conventional electrolyte (the concentration of LiPF6 was 1 mol·L -1). A certain amount of the obtained conventional electrolyte was added with fluoroethylene carbonate (FEC) (8% by mass) and tris(trimethylsilyl)phosphite (TMSP) (2% by mass), respectively, mixed uniformly, and left to stand for 24 hours. The obtained electrolytes were denoted as FEC electrolyte and TMSP electrolyte, respectively. The prepared electrolytes were subjected to nuclear magnetic resonance (NMR) test.

[0076] 2. Result analysis: The conventional electrolyte was compared with the FEC electrolyte and the TMSP electrolyte. 31 P NMR chart ( Figure 1 ) of the conventional electrolyte showed characteristic peaks of PF6 - of LiPF6 at -133.1-153.4 ppm, peaks of decomposition and hydrolysis products of LiPF6 at -33.2 ppm and -37.2 ppm (corresponding to PO3F2 - and PO2F 2- , respectively), respectively. 19 F NMR chart ( Figure 2 ) of the conventional electrolyte showed characteristic doublet peaks of PF6 - of LiPF6 at -73.8 ppm and -78.3 ppm, peaks of decomposition and hydrolysis products of LiPF6 at -87.2 ppm, -89.1 ppm and -191.8 ppm (corresponding to PO3F2 - , PO2F 2- and HF, respectively), respectively. 31 P NMR chart ( Figure 1 ) of the FEC electrolyte showed characteristic 7-peak of PF6 - at -133.1-153.4 ppm, and peaks of PO3F2 - at -33.2 ppm and PO2F 2- at -37.2 ppm were weakened, indicating that FEC had the function of inhibiting decomposition and hydrolysis of LiPF6. 19 F NMR chart ( Figure 2 ) of the FEC electrolyte showed characteristic doublet peaks of PF6 - at -73.8 ppm and -78.3 ppm, and new peaks at -121.6 ppm and -123.6 ppm were characteristic peaks of FEC. Peaks of PO3F2 - at -87.2 ppm, PO2F 2- at -89.1 ppm and HF at -191.8 ppm were weakened, confirming that FEC had the function of inhibiting decomposition and hydrolysis of LiPF6. 31 P NMR chart ( Figure 1 ) of the TMSP electrolyte showed characteristic 7-peak of PF6- The characteristic 7-peak (-133.1 - -153.4 ppm) of PF6 still exists, and a new peak at 113.4 ppm is the characteristic peak of the phosphite structure of TMSP (i.e. (TMSO)3P:). The new peaks at -13.8 ppm and -27.5 ppm are attributed to the products of the reaction of TMSP with O2, H2O (corresponding to (TMSO)3PO and (TMSO)2PHO, respectively), and PO3F2 - The peaks of PO2F 2- (-33.2 ppm) and PO2F 19 (-37.2 ppm) disappear, indicating that TMSP has the function of removing O2 and H2O impurities in the electrolyte and inhibiting the decomposition and hydrolysis of LiPF6; - F NMR chart ( Figure 2 ), the characteristic doublet peak (-73.8 ppm, -78.3 ppm) of PF6 - still exists, but the peaks of PO3F2 2- (-87.2 ppm), PO2F 31 (-89.1 ppm) and HF (-191.8 ppm) all disappear, confirming that TMSP has the function of removing O2 and H2O impurities in the electrolyte and inhibiting the decomposition and hydrolysis of LiPF6.

[0077] Example 1: Preparation of electrolyte containing Lewis acid-base complex additive and physicochemical properties

[0078] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, FEC (8% by mass ratio) and TMSP (2% by mass ratio) were simultaneously added into a certain amount of the conventional electrolyte prepared in Comparative Example 1, and mixed uniformly. The obtained electrolyte was denoted as TMSP:FEC electrolyte. The prepared electrolyte was subjected to NMR test.

[0079] 2. Result analysis: compared with the conventional electrolyte of Comparative Example 1, the FEC electrolyte and the TMSP electrolyte, the TMSP:FEC electrolyte has the following characteristics: 31 P NMR chart ( Figure 1 ), the characteristic 7-peak (-133.1 - -153.4 ppm) of PF6 - still exists, the characteristic peak (113.4 ppm) of (TMSO)3P: of TMSP disappears, and a new peak (as indicated by the arrow in Figure 1 ) appears at 1.78 ppm, which means that TMSP is consumed by FEC (i.e. the reaction between the two occurs) and a new compound is generated. The peaks of (TMSO)3PO (-13.8 ppm) and (TMSO)2PHO) (-27.5 ppm) still exist, and PO3F2 -(-33.2 ppm) and PO2F 2- (-37.2 ppm) disappeared, indicating that the new compound generated from the reaction between TMSP and FEC maintained the function of TMSP to remove O2 and H2O impurities in the electrolyte and the function of FEC and TMSP to inhibit the decomposition and hydrolysis of LiPF6; 19 F NMR chart ( Figure 2 ) in which the characteristic doublet of PF6 - (-73.8 ppm, -78.3 ppm) still existed, the characteristic peaks of FEC (-121.6 ppm, -123.6 ppm) still existed (Note: FEC was in excess of TMSP in the electrolyte), and a new peak (as indicated by the arrow in Figure 2 ) appeared at 157.8 ppm, confirming the reaction between TMSP and FEC and the generation of a new compound. The peaks of PO3F2 - (-87.2 ppm), PO2F 2- (-89.1 ppm) and HF (-191.8 ppm) disappeared, confirming that the new compound generated from the reaction between TMSP and FEC maintained the function of TMSP to remove O2 and H2O impurities in the electrolyte and the function of FEC and TMSP to inhibit the decomposition and hydrolysis of LiPF6. Since the lone pair of electrons on the trivalent phosphorus atom of TMSP has a strong ability to provide electrons (i.e., a Lewis base), and the carbon atom on the carbonate structure of FEC (which has a high positive charge due to the strong electron-withdrawing property of the fluorine atom) has a strong ability to accept electrons (i.e., a Lewis acid), a Lewis acid-base coordination reaction can occur between them, generating a new compound (as indicated by the arrow in Figure 1 and Figure 2 ) in situ in the electrolyte, i.e., a Lewis acid-base complex (denoted as TMSP:FEC here). Furthermore, the Lewis acid-base complex maintains the properties of its constituent components (i.e., the Lewis acid FEC and the Lewis base TMSP).

[0080] Example 2: Electrochemical performance of the electrolyte prepared in Example 1

[0081] 1. The conventional electrolyte prepared in Comparative Example 1 was subjected to cyclic voltammetry (CV) testing at a scan rate of 0.5 mV s -1 using a glassy carbon electrode as the working electrode, platinum as the counter electrode, and lithium sheet as the reference electrode.

[0082] 2. Analysis of the results: In the first cycle (CV1) of the negative CV of the conventional electrolyte, Figure 3 a) the large background reduction current was attributed to the reduction of reducible impurities in the electrolyte (including O2, H2O, and the decomposition and hydrolysis products of LiPF6), and the peak at 1.88 V was the reduction of LiPF6 and the peak at 0.43 V was the reduction of EC. In the fifth cycle (CV5) of the negative CV of the conventional electrolyte,Figure 3 After b), a large background reduction current is still maintained, indicating that the SEI film initially formed by the electrolyte reduction at the negative electrode cannot effectively suppress its subsequent continuous reduction and decomposition; the first cycle of the forward CV ( Figure 4 In circle a), the peak appearing at 4.90 V represents the oxidation of the electrolyte by a conventional carbonate solvent. (Fifth circle) Figure 4 b) After that, the background oxidation current is still large, indicating that the CEI film formed by the electrolyte in the early oxidation at the positive electrode cannot effectively inhibit its subsequent continuous oxidation and decomposition, corresponding to a narrow electrochemical window (4.90 V).

[0083] Example 2: Electrochemical performance of electrolyte containing Lewis acid-base complex additives

[0084] 1. The CV test was performed on the TMSP:FEC electrolyte prepared in Example 1 under the same conditions as Comparative Example 2.

[0085] 2. Results Analysis: Compared with the conventional electrolyte of Comparative Example 2, the first cycle of negative CV of the TMSP:FEC electrolyte ( Figure 3 In a), the smaller background reduction current confirms that the Lewis acid-base complex TMSP:FEC generated in situ in the electrolyte possesses the function of removing O2 and H2O impurities from the electrolyte and inhibiting the decomposition and hydrolysis of LiPF6 (e.g., Figure 1 and Figure 2 (As shown). The peak at 1.71 V represents the reduction of residual FEC in the electrolyte. The new peak appearing at 0.80 V can be attributed to the reduction of TMSP:FEC, indicating that this Lewis acid-base complex can be preferentially reduced at the negative electrode before EC to form the SEI film. Fifth circle ( Figure 3 After b), a very small background reduction current was observed, indicating that the SEI film preferentially reduced by TMSP:FEC at the negative electrode can effectively suppress the continuous reduction and decomposition of the electrolyte; the first cycle of the forward CV ( Figure 4 In circle a), the new peak appearing at 4.20 V can be attributed to the oxidation of TMSP:FEC, indicating that this Lewis acid-base complex can be preferentially oxidized at the cathode before conventional carbonate solvents to form a CEI film. (Fifth circle) Figure 4 b) After that, a very small background oxidation current was observed, indicating that the CEI film preferentially oxidized by TMSP:FEC on the positive electrode can effectively suppress the continuous oxidative decomposition of the electrolyte, corresponding to a wide electrochemical window (6.52 V).

[0086] Comparative Example 3: LNMO / / Li lithium metal battery based on conventional electrolyte

[0087] 1. Under an inert gas atmosphere with controlled oxygen <1 ppm and moisture <1 ppm, a certain amount of LiPF6 was added to an organic solvent of EC / DMC / EMC (volume ratio 1:1:1), mixed thoroughly, and allowed to stand for 24 hours to obtain a conventional electrolyte (LiPF6 concentration 1 mol·L⁻¹). -1 The resulting electrolyte, polypropylene and polyethylene composite porous film, lithium (Li) anode sheet, and LiNi alloy were then combined. 0.5 Mn 1.5 O4 (LNMO) cathode sheets (composition mass ratio, LNMO:SP:CNT:PVDF=80:9.7:0.3:10) were packaged into CR2025 coin-type LNMO / / Li lithium metal batteries. Electrochemical tests were performed on the assembled batteries (voltage range 3.5–4.95 V, 1 C current defined as 148 mA g). -1 Electrochemical impedance spectroscopy (EIS) frequency range was 10 mHz to 100 kHz, and AC amplitude was 10 mV. The morphology of the electrodes after charge-discharge cycles was characterized (including scanning electron microscopy (SEM) and transmission electron microscopy (TEM)).

[0088] 2. Results Analysis: The LNMO / / Li lithium metal battery based on a conventional electrolyte exhibited a high impedance (26.04 Ω) after activation at 0.1 C. Figure 5 The capacity retention rate after 200 charge-discharge cycles at 1 C was only 41.2%. Figure 6 ). with fresh Li anode ( Figure 7 a, Figure 8 Compared to a), the cycled Li anode has numerous cracks and a thicker layer of moss-like dead lithium. Figure 7 b、 Figure 8 (b) indicates that the SEI film formed by the conventional electrolyte on the Li anode is unstable and cannot effectively suppress the continuous reductive decomposition of the electrolyte (e.g., Figure 3 (as shown in b), and this SEI film has poor Li affinity and Li + Diffusion kinetics lead to the continuous rupture, reconstruction, and thickening of the SEI film, as well as the continuous growth of lithium dendrites and the continuous accumulation of deactivated lithium (dead lithium); and the fresh LNMO cathode ( Figure 9 a, Figure 10 In contrast, a thicker, looser, broken, and uneven CEI film with particulate deposits formed on the LNMO cathode after cycling. Figure 9 b、 Figure 10 (b) indicates that the CEI film formed at the LNMO cathode by the conventional electrolyte is unstable and cannot effectively inhibit the continuous oxidative decomposition of the electrolyte (e.g., Figure 4(As shown in b), this leads to the continuous rupture, rebuilding, and thickening of the CEI film. In summary, due to the poor performance of the SEI and CEI films generated at the negative and positive electrodes by conventional electrolytes, respectively, the LNMO / / Li lithium metal battery exhibits extremely poor cycle life.

[0089] Example 3: LNMO / / Li lithium metal battery based on electrolyte containing Lewis acid-base complex additives

[0090] 1. Under an inert gas atmosphere with controlled oxygen <1ppm and moisture <1ppm, FEC (8% by mass) and TMSP (2% by mass) were simultaneously added to a certain amount of conventional electrolyte prepared in Comparative Example 3. The mixture was thoroughly mixed and allowed to stand for 24 hours to obtain a TMSP:FEC electrolyte. The obtained electrolyte was then used for the encapsulation and testing of LNMO / / Li lithium metal batteries according to the method of Comparative Example 3.

[0091] 2. Results Analysis: Compared with the LNMO / / Li lithium metal battery based on conventional electrolyte in Comparative Example 3, the LNMO / / Li lithium metal battery based on TMSP:FEC electrolyte showed a lower impedance (16.88 Ω) after activation at 0.1 C. Figure 5 The capacity retention rate after 460 charge-discharge cycles at 1 C is as high as 98.4%. Figure 6 ). Compared with the Li anode in conventional electrolytes ( Figure 7 b、 Figure 8 (b) In comparison, the SEI film formed on the Li anode after cycling in TMSP:FEC electrolyte is thinner and there are no lithium dendrites or cracks. Figure 7 c. Figure 8 c) indicates that the Lewis acid-base complexes in the TMSP:FEC electrolyte preferentially reduce to form a more stable SEI film at the negative electrode, effectively inhibiting the continuous reductive decomposition of the electrolyte (e.g., Figure 3 (As shown in b), this avoids the rupture, rebuilding, and thickening of the SEI film. Simultaneously, this SEI film possesses superior Li affinity and Li... + Diffusion kinetics can effectively induce uniform deposition and dissolution of Li, avoiding the growth of lithium dendrites and the formation of deactivated lithium (dead lithium). This is different from the LNMO cathode in conventional electrolytes (…). Figure 9 b、 Figure 10 (b) In comparison, the CEI film generated after cycling in TMSP:FEC electrolyte is thinner, denser, unbroken, uniform, and free of particulate deposits. Figure 9 c. Figure 10 c) indicates that the Lewis acid-base complexes in the TMSP:FEC electrolyte preferentially oxidize at the positive electrode to form a relatively stable CEI film, which can effectively inhibit the continuous oxidative decomposition of the electrolyte (e.g., Figure 4b), avoiding the rupture, reconstruction, and thickening of the CEI film. In summary, due to the Lewis acid-base complex in the TMSP:FEC electrolyte, the LNMO / / Li lithium metal battery exhibits superior cycle life because the SEI film and the CEI film with excellent performance are preferentially generated on the negative electrode and the positive electrode, respectively.

[0092] Comparative Example 4: NCM811 / / Li lithium metal battery based on conventional electrolyte

[0093] 1. Under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of LiPF6 was added to an organic solvent of EC / DMC / EMC (1:1:1 by volume ratio) and mixed uniformly, and then left to stand for 24 hours to obtain a conventional electrolyte (LiPF6 concentration of 1 mol·L -1 ). The obtained electrolyte, polypropylene and polyethylene composite porous film, lithium (Li) negative electrode sheet, LiNi 0.8 Mn 0.1 Co 0.1 O2(NCM811) positive electrode sheet (mass ratio, NCM811:SP:CNT:PVDF=90:4.9:0.1:5) were packaged into a CR2025 button-shaped NCM811 / / Li lithium metal battery. The assembled battery was subjected to electrochemical tests (voltage range of 3.0-4.3 V, 1 C current defined as 200 mA g -1 ; EIS frequency range of 10 mHz-100 kHz, AC amplitude of 10 mV).

[0094] 2. Result analysis: the NCM811 / / Li lithium metal battery based on the conventional electrolyte showed a relatively high impedance (21.28 Ω, Figure 11 ) after 0.1 C activation, and the capacity retention rate was only 46.5% ( Figure 12 ) after 1 C charge-discharge cycle for 100 cycles, confirming the poor performance of the SEI film and the CEI film generated by the conventional electrolyte at the negative electrode and the positive electrode, respectively.

[0095] Example 4: NCM811 / / Li lithium metal battery based on electrolyte containing Lewis acid-base complex additive

[0096] 1. Under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, FEC (20% by mass ratio) and TMSP (5% by mass ratio) were simultaneously added to a certain amount of the conventional electrolyte prepared in Comparative Example 4, and then mixed uniformly and left to stand for 24 hours to obtain a TMSP:FEC electrolyte. The obtained electrolyte was subjected to packaging and testing of NCM811 / / Li lithium metal battery according to the method of Comparative Example 4.

[0097] 2. Result analysis: Compared with the NCM811 / / Li lithium metal battery based on the conventional electrolyte of Comparative Example 4, the NCM811 / / Li lithium metal battery based on the TMSP:FEC electrolyte showed a lower impedance (18.52 Ω, Figure 11 ) after 0.1 C activation, and a capacity retention rate as high as 87.3% ( Figure 12 ) after 1 C charge-discharge cycle for 200 cycles, which confirmed the excellent performance of the SEI film and CEI film generated by the Lewis acid-base complex in the TMSP:FEC electrolyte on the negative electrode and the positive electrode, respectively.

[0098] Comparative Example 5: LFP / / Li lithium metal battery based on conventional electrolyte

[0099] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of LiPF6 was added to the organic solvent of EC / EMC (by volume ratio, 1:2) and mixed uniformly, and then left for 24 hours to obtain the conventional electrolyte (the concentration of LiPF6 was 1 mol·L -1 ). The obtained electrolyte, polypropylene and polyethylene composite porous film, lithium (Li) negative electrode sheet, and LiFePO4 (LFP) positive electrode sheet (the mass ratio was LFP:SP:CNT:PVDF = 91:3:1:5) were packaged into a CR2025 button LFP / / Li lithium metal battery. The assembled battery was subjected to electrochemical test (the voltage range was 2.0-4.0 V, and the 1 C current was defined as 170 mA g -1 ; the EIS frequency range was 10 mHz-100 kHz, and the AC amplitude was 10 mV).

[0100] 2. Result analysis: The LFP / / Li lithium metal battery based on the conventional electrolyte showed a higher impedance (21.83 Ω, Figure 13 ) after 0.1 C activation, and a capacity retention rate of only 51.2% ( Figure 14 ) after 1 C charge-discharge cycle for 120 cycles, which confirmed the poor performance of the SEI film and CEI film generated by the conventional electrolyte on the negative electrode and the positive electrode, respectively.

[0101] Example 5: LFP / / Li lithium metal battery based on electrolyte containing Lewis acid-base complex additive

[0102] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, FEC (by mass ratio, 8%) and TMSP (by mass ratio, 2%) were simultaneously added to a certain amount of the conventional electrolyte prepared in Comparative Example 5, and then mixed uniformly and left for 24 hours to obtain the TMSP:FEC electrolyte. The obtained electrolyte was packaged and tested for the LFP / / Li lithium metal battery according to the method of Comparative Example 5.

[0103] 2. Result analysis: Compared with the LFP / / Li lithium metal battery based on the conventional electrolyte of Comparative Example 5, the LFP / / Li lithium metal battery based on the TMSP:FEC electrolyte showed a lower impedance (16.37 Ω, Figure 13 ) after 0.1 C activation, and a capacity retention rate as high as 94.7% (after 380 cycles at 1 C charge and discharge, Figure 14 ) confirmed the excellent performance of the Lewis acid-base complex in the TMSP:FEC electrolyte to generate SEI film and CEI film on the negative electrode and positive electrode, respectively.

[0104] Comparative Example 6: LNMO / / Gr lithium ion battery based on conventional electrolyte

[0105] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of LiPF6 was added to the organic solvent of EC / DMC / EMC (volume ratio, 1:1:1) and mixed uniformly, and then left for 24 hours to obtain the conventional electrolyte (LiPF6 concentration was 1.5 mol·L -1 ). The obtained electrolyte, polypropylene and polyethylene composite porous film, graphite (Gr) negative electrode sheet (composition mass ratio, Gr:SP:CNT:PVDF = 87:2.8:0.2:10), LNMO positive electrode sheet (composition mass ratio, LNMO:SP:CNT:PVDF = 90:4.5:0.5:5) were packaged into CR2025 button LNMO / / Gr lithium ion battery. The assembled battery was subjected to electrochemical test (voltage range was 3.0-4.85 V, 1 C current was defined as 148 mA g -1 ; EIS frequency range was 10 mHz-100 kHz, and AC amplitude was 10 mV).

[0106] 2. Result analysis: The LNMO / / Gr lithium ion battery based on the conventional electrolyte showed a higher impedance (28.78 Ω, Figure 15 ) after 0.1 C activation, and a capacity retention rate of only 25.5% (after 150 cycles at 1 C charge and discharge, Figure 16 ) confirmed the poor performance of the SEI film and CEI film generated by the conventional electrolyte on the negative electrode and positive electrode, respectively.

[0107] Example 6: LNMO / / Gr lithium ion battery based on electrolyte containing Lewis acid-base complex additive

[0108] 1. Under the condition of inert gas atmosphere (oxygen < 1 ppm and moisture < 1 ppm), a certain amount of FEC (5% by mass ratio) and TMSP (1% by mass ratio) were added into the conventional electrolyte prepared in Comparative Example 6, and mixed uniformly. After standing for 24 hours, a TMSP:FEC electrolyte was obtained. The obtained electrolyte was encapsulated into LNMO / / Gr lithium ion batteries and tested according to the method of Comparative Example 6.

[0109] 2. Result analysis: Compared with the LNMO / / Gr lithium ion battery based on the conventional electrolyte of Comparative Example 6, the LNMO / / Gr lithium ion battery based on the TMSP:FEC electrolyte showed a lower impedance (25.77 Ω, Figure 15 ) after 0.1 C activation, and a capacity retention rate as high as 90.0% ( Figure 16 ) after 1 C charge-discharge cycle for 250 cycles, which confirmed the excellent performance of the SEI film and CEI film generated by the Lewis acid-base complex in the TMSP:FEC electrolyte on the negative electrode and positive electrode, respectively.

[0110] Comparative Example 7: LNMO / / AC lithium ion supercapacitor based on conventional electrolyte

[0111] 1. Under the condition of inert gas atmosphere (oxygen < 1 ppm and moisture < 1 ppm), a certain amount of LiPF6 was added into the organic solvent of EC / DMC / EMC (1:1:1 by volume ratio), and mixed uniformly. After standing for 24 hours, a conventional electrolyte (LiPF6 concentration of 1 mol·L -1 ) was obtained. The obtained electrolyte, polypropylene and polyethylene composite porous film, activated carbon (AC) negative electrode sheet (composition mass ratio, AC:SP:CNT:SBR:CMC = 90:4.375:0.625:2:3), LNMO positive electrode sheet (composition mass ratio, LNMO:SP:CNT:PVDF = 80:9.7:0.3:10) were encapsulated into CR2025 button LNMO / / AC lithium ion supercapacitors. The assembled capacitors were subjected to electrochemical test (voltage range of 0-3.45 V, 1 C current defined as 30 mA g -1 ; EIS frequency range of 10 mHz-100 kHz, AC amplitude of 10 mV).

[0112] 2. Result analysis: The LNMO / / AC lithium ion supercapacitor based on the conventional electrolyte showed a higher impedance (119.9 Ω, Figure 17 ) after 0.5 C activation, and a capacity retention rate of only 34.0% ( Figure 18 ) after 10 C charge-discharge cycle for 3000 cycles, which confirmed the poor performance of the SEI film and CEI film generated by the conventional electrolyte on the negative electrode and positive electrode, respectively.

[0113] Example 7: LNMO / / AC lithium-ion supercapacitor based on electrolyte containing Lewis acid-base complex additive

[0114] 1. Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of FEC (1% by mass ratio) and TMSP (5% by mass ratio) were added into the conventional electrolyte prepared in Comparative Example 7, and mixed uniformly. After standing for 24 hours, a TMSP:FEC electrolyte was obtained. The obtained electrolyte was packaged and tested for LNMO / / AC lithium-ion supercapacitor according to the method of Comparative Example 7.

[0115] Result analysis: Compared with the LNMO / / AC lithium-ion supercapacitor based on the conventional electrolyte of Comparative Example 7, the LNMO / / AC lithium-ion supercapacitor based on the TMSP:FEC electrolyte showed lower impedance (24.3 Ω, Figure 17 ) after 0.5 C activation, and the capacity retention rate was as high as 98.7% ( Figure 18 ) after 10 C charge-discharge cycle for 6300 cycles, which confirmed the excellent performance of the SEI film and CEI film generated by the Lewis acid-base complex in the TMSP:FEC electrolyte on the negative electrode and the positive electrode, respectively.

[0116] Example 8

[0117] Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of LiBOB was added into the organic solvent of DEC / FEC (1:1 by volume ratio), and mixed uniformly. After standing for 12 hours, a conventional electrolyte (LiBOB concentration was 0.1 mol·L -1 ).

[0118] A certain amount of the obtained conventional electrolyte was taken, and boron trifluoride (BF3) (0.1% by mass ratio) and pyridine (C5H5N) (0.1% by mass ratio) were added respectively, and mixed uniformly. After standing for 12 hours, an electrolyte containing multifunctional additive of Lewis acid-base complex generated in situ was obtained.

[0119] Example 9

[0120] Under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, a certain amount of NaBF4 and NaTFSI were added into the organic solvent of PC, and mixed uniformly. After standing for 36 hours, a conventional electrolyte (NaBF4 concentration was 5 mol·L -1 , and NaTFSI concentration was 5 mol·L -1 ).

[0121] A certain amount of the obtained conventional electrolyte was taken, and iron trichloride (FeCl3), aluminum trichloride (AlCl3) (10%, 10% by mass ratio), and triethanolamine (TEA), hexamethyldisilazane (HMDS) (10%, 10% by mass ratio) were added respectively, mixed uniformly, and left to stand for 36 hours to obtain an electrolyte containing Lewis acid-base complex multifunctional additives generated in situ.

[0122] Example 10

[0123] A certain amount of NaODFB, NaPO2F2, and NaODFP was added to an organic solvent of TFPC / GBL / GVL (1:1:2 by volume ratio) under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, mixed uniformly, and left to stand for 24 hours to obtain a conventional electrolyte (NaODFB concentration of 1 mol·L -1 , NaPO2F2 concentration of 2 mol·L -1 , and NaODFP concentration of 0.5 mol·L -1 ).

[0124] A certain amount of the obtained conventional electrolyte was taken, and fluoroethylene carbonate (FEC) (7% by mass ratio) and diethyl ether (C2H5OC2H5) (6% by mass ratio) were added respectively, mixed uniformly, and left to stand for 20 hours to obtain an electrolyte containing Lewis acid-base complex multifunctional additives generated in situ.

[0125] Example 11

[0126] A certain amount of KFSI was added to an organic solvent of DMF / AN / FAN (1:3:1 by volume ratio) under the condition of an inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, mixed uniformly, and left to stand for 30 hours to obtain a conventional electrolyte (KFSI concentration of 7 mol·L -1 ).

[0127] A certain amount of the obtained conventional electrolyte was taken, and difluoroethylene carbonate (DFEC) (0.8% by mass ratio) and hexa(2,2,2-trifluoroethoxy)cyclotriphosphazene (HFEPN), lithium 4,5-dicyano-2-(trifluoromethyl)isopyrazole (LiTDI) (0.8%, 2% by mass ratio) were added respectively, mixed uniformly, and left to stand for 32 hours to obtain an electrolyte containing Lewis acid-base complex multifunctional additives generated in situ.

[0128] Example 12

[0129] A certain amount of KBOB was added in DMF / AN / FAN (volume ratio, 1:2:1) organic solvent under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, mixed uniformly, and left for 28 hours to obtain a conventional electrolyte (KBOB concentration was 8 mol·L -1 )。

[0130] A certain amount of the conventional electrolyte was taken, and γ-butyrolactone (GBL) (mass ratio, 3%) and diphenyldimethoxysilane (DPDMS), 1,3-bis(1-isocyanate-1-methylethyl)benzene (mass ratio, 1%, 1.5%) were added respectively, mixed uniformly, and left for 25 hours to obtain an electrolyte containing Lewis acid-base complex multifunctional additives generated in situ.

[0131] Example 13

[0132] A certain amount of KBOB was added in DMF / AN / FAN (volume ratio, 1:2:1) organic solvent under the condition of inert gas atmosphere with oxygen <1 ppm and moisture <1 ppm, mixed uniformly, and left for 28 hours to obtain a conventional electrolyte (KBOB concentration was 8 mol·L -1 )。

[0133] A certain amount of the conventional electrolyte was taken, and γ-butyrolactone (GBL) (mass ratio, 3%) and diphenyldimethoxysilane (DPDMS), 1,3-bis(1-isocyanate-1-methylethyl)benzene (mass ratio, 1%, 1.5%) were added respectively, mixed uniformly, and left for 25 hours to obtain an electrolyte containing Lewis acid-base complex multifunctional additives generated in situ.

[0134] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for the preparation of an in situ generated electrolyte additive, characterized in that, The additive is a Lewis acid-base complex multifunctional additive; the Lewis acid-base complex multifunctional additive is prepared by adding a Lewis acid and a Lewis base into a conventional electrolyte, and then by a Lewis acid-base coordination reaction between the Lewis acid and the Lewis base; The Lewis acid is at least one of boron trifluoride, ferric trichloride, aluminum trichloride, fluoroethylene carbonate and difluoroethylene carbonate; The Lewis base is at least one of diphenyldimethoxysilane, hexamethyldisilazane, 1,3-bis(1-isocyanato-1-methylethyl)benzene, tris(trimethylsilyl) phosphite, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, pyridine, diethyl ether, hexakis(2,2,2-trifluoroethoxy)cyclotriphosphazene, triethanolamine and lithium 4,5-dicyano-2-(trifluoromethyl)isopyrazole; The preparation method of the in-situ generated electrolyte additive is that the Lewis acid and the Lewis base are added into the conventional electrolyte to perform a Lewis acid-base coordination reaction under an inert gas atmosphere, and the in-situ generated electrolyte additive is obtained; The inert gas atmosphere is specifically oxygen < 1 ppm and moisture < 1 ppm; The Lewis acid-base coordination reaction time is 12-36 h; The added mass of the Lewis acid is 0.1-20% of the mass of the conventional electrolyte; the added mass of the Lewis base is 0.1-20% of the mass of the conventional electrolyte; The conventional electrolyte is mixed by an organic solvent and an electrolyte salt; the electrolyte salt in the conventional electrolyte is a lithium salt; the electrolyte salt is at least one of perchlorate, hexafluorophosphate, bisoxalate borate, tetrafluoroborate, difluoro oxalate borate, bis(trifluoromethylsulfonyl) imide, bis(fluorosulfonyl) imide, difluorophosphate and difluoro oxalate phosphate.

2. An electrolyte, characterized by The electrolyte is added with the electrolyte additive prepared by the preparation method of the in-situ generated electrolyte additive according to claim 1.

3. An electrochemical energy storage device, characterized by, The electrolyte of the electrochemical energy storage device is added with the electrolyte additive prepared by the preparation method of the in-situ generated electrolyte additive according to claim 1.

4. The electrochemical energy storage device of claim 3, wherein, The electrochemical energy storage device comprises a shell, a positive electrode and a negative electrode installed in the shell, and a separator; the separator is arranged between the positive electrode and the negative electrode; the space between the positive electrode and the separator and the space between the negative electrode and the separator are both filled with an electrolyte, and the electrolyte is added with the electrolyte additive prepared by the preparation method of the in-situ generated electrolyte additive according to claim 1.

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