CN116315109A - High-electrochemical window magnesium ion battery electrolyte, preparation method and application thereof - Google Patents
High-electrochemical window magnesium ion battery electrolyte, preparation method and application thereof Download PDFInfo
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- CN116315109A CN116315109A CN202310292026.7A CN202310292026A CN116315109A CN 116315109 A CN116315109 A CN 116315109A CN 202310292026 A CN202310292026 A CN 202310292026A CN 116315109 A CN116315109 A CN 116315109A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 97
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 229910001425 magnesium ion Inorganic materials 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000011777 magnesium Substances 0.000 claims abstract description 67
- 159000000003 magnesium salts Chemical class 0.000 claims abstract description 20
- 150000003242 quaternary ammonium salts Chemical class 0.000 claims abstract description 19
- 239000003960 organic solvent Substances 0.000 claims abstract description 17
- 238000000034 method Methods 0.000 claims abstract description 13
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims abstract description 11
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims abstract description 7
- ZUHZGEOKBKGPSW-UHFFFAOYSA-N tetraglyme Chemical compound COCCOCCOCCOCCOC ZUHZGEOKBKGPSW-UHFFFAOYSA-N 0.000 claims abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims abstract description 3
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims abstract description 3
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000001291 vacuum drying Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000002808 molecular sieve Substances 0.000 claims description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 238000004090 dissolution Methods 0.000 description 25
- 230000008021 deposition Effects 0.000 description 24
- 229910001220 stainless steel Inorganic materials 0.000 description 22
- 239000010935 stainless steel Substances 0.000 description 22
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 13
- 229910052749 magnesium Inorganic materials 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 238000012360 testing method Methods 0.000 description 10
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 9
- 239000000654 additive Substances 0.000 description 7
- 210000004027 cell Anatomy 0.000 description 7
- 230000002441 reversible effect Effects 0.000 description 7
- 230000000996 additive effect Effects 0.000 description 5
- 230000000269 nucleophilic effect Effects 0.000 description 5
- 230000010287 polarization Effects 0.000 description 5
- 238000007789 sealing Methods 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 3
- 239000013256 coordination polymer Substances 0.000 description 3
- 238000002484 cyclic voltammetry Methods 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- -1 ion salts Chemical class 0.000 description 3
- 238000002161 passivation Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- NQZKZGHOYUYCHU-UHFFFAOYSA-N boron;tetraethylazanium Chemical compound [B].CC[N+](CC)(CC)CC NQZKZGHOYUYCHU-UHFFFAOYSA-N 0.000 description 2
- 230000022131 cell cycle Effects 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003365 glass fiber Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000013112 stability test Methods 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- 238000004832 voltammetry Methods 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 230000008846 dynamic interplay Effects 0.000 description 1
- 239000012039 electrophile Substances 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 125000001033 ether group Chemical group 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011874 heated mixture Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003880 polar aprotic solvent Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000001075 voltammogram Methods 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a magnesium ion battery electrolyte with a high electrochemical window, a preparation method and application thereof, wherein the electrolyte comprises an organic solvent, a magnesium salt electrolyte and quaternary ammonium salt; the organic solvent is one or a mixture of more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tetrahydrofuran; the magnesium salt electrolyte is Mg (TFSI) 2 、Mg(OTf) 2 、MgCl 2 And AlCl 3 、Mg(BH 4 ) 2 、Mg[B(hfip) 4 ] 2 One or more of MgBOR; the quaternary ammonium salt has a general formula of N + (R 1 R 2 R 3 R 4 ) The method comprises the steps of carrying out a first treatment on the surface of the Which is a kind ofWherein R is 1 、R 2 、R 3 、R 4 One or more of straight chain or branched chain with carbon number of 1-10.
Description
Technical Field
The invention relates to the technical field of magnesium ion batteries, in particular to a magnesium ion battery electrolyte with a high electrochemical window, a preparation method and application thereof.
Background
Nowadays, portable electronic products and electric vehicles place higher demands on secondary energy storage batteries. In recent years, magnesium ion batteries have been known to have a high volumetric specific energy (3832 mAh/cm 3 ) The advantages of negative redox potential (-2.37 v vs. she), high crust abundance, good safety, etc. are of great interest and are considered as a promising candidate for new lithium battery technologies. However, due to the severe passivation of magnesium anodes and slow diffusion kinetics of the positive electrode, the power density of most rechargeable magnesium cells is very low (< 0.5kW kg) -1 ,0.8mW cm -2 )。
The electrolyte acts as the "blood" of the cell and plays a critical role in the overall performance of the cell. Interfacial layers caused by electrolyte decomposition in magnesium ion batteries generally hinder Mg 2+ And therefore most simple ion salts (such as Mg (ClO) 4 ) 2 And Mg (BF 4 ) 2 ) And polar aprotic solvents (such as carbonates and nitriles) are not suitable for use as electrolytes for magnesium ion batteries. In the existing magnesium ion battery electrolyte technology, the nucleophilic electrolyte can be compatible with the Mg intercalation positive electrode, but the Mg at room temperature 2+ Is subject to Mg at the electrode/electrolyte interface 2+ The high energy barrier of desolventization and its significant limitation of low diffusion rates in materials. In addition, nucleophilic components are susceptible to chemical reactions with electrophiles and are not suitable for use in organic polymer electrodes and switching positive electrodes (e.g., sulfur, iodine). The non-nucleophilic electrolyte components are now largely explored, wherein MgTFSI 2 As a common component of the electrolyte,attention has been paid to the advantages of being very soluble in ethers, having a wide electrochemical window and high electrical conductivity.
However, using a single Mg (TFSI) 2 The electrolyte of (C) shows a large overpotential (> 2.0V) and a low CE (< 50%) even at high temperatures. Mg (TFSI) 2 The electrolyte is very sensitive to impurities and thus strongly influences its Mg deposition/dissolution properties. Cl-can be prepared by Cl - And H is 2 The complex dynamic interactions of O protect Mg surfaces from passivation by trace amounts of moisture. Thus, in Mg (TFSI) 2 MgCl introduction in electrolyte 2 Is an effective strategy to achieve reversible deposition/dissolution and reduce overpotential. Mg (TFSI) 2 -MgCl 2 In DME, the CE can be increased to 80%, the overpotential reaches 400mV and the negative electrode stability limit is 3.5V. Except for consuming impurities in water, mgCl 2 Also contributes to the formation of [ Mg ] x Cl y ] n+ An electroactive species. Mg (TFSI) 2 -MgCl 2 The active cations in THF are mainly Cl-components in the electrolyte. Notably, mg (TFSI) -based 2 The properties of the electrolyte of (2) are highly dependent on the purity of the Mg salt, and MgCl removal can be achieved by introducing 2 Other reagents are added. The prior art also found that by adding a trace amount of Mg (BH 4 ) 2 Water scavenger, deposition/dissolution overpotential in Mg (TFSI) 2 about-0.35V (deposit) and 0V (dissolution) in the/G4 electrolyte, the CE for the first cycle was 84% and remained 75% after 500 cycles. In addition, dimethylamine (DMA) can be used as cosolvent to prepare chlorine-free and corrosion-free Mg (TFSI) 2 The base electrolyte had a polarizability of 210mV after more than 1500min in a symmetrical Mg cell cycle, comparable to the performance in APC electrolyte. When DMA-THF-G4 was used as a mixed solvent, CE increased to 75%, while Mg (TFSI) 2 The CE of the G4 electrolyte is only 38%. The prior art also uses rPDI as an additive to add Mg (TFSI) 2 The DME electrolyte has high air tolerance, and can be assembled into a battery to work normally after being exposed in the air, and the temperature is 1.0mA/cm 2 Can be cycled for 300h under the current density of 250mV polarization, and can bear the maximum current density of up to 5mA/cm 2 The method comprises the steps of carrying out a first treatment on the surface of the But the electrochemical window is not high, only about 2.0V on copper foil.
To sum up, the existing MgTFSI 2 In the electrolyte technology, most of the disadvantages of low deposition and dissolution efficiency, large overpotential, narrow potential window, large corrosiveness to a current collector and the like still exist.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a magnesium ion battery electrolyte with a high electrochemical window, a preparation method and application thereof, so as to solve the problems of low deposition and dissolution efficiency, large overpotential, narrow potential window and large corrosiveness to a current collector in the electrolyte in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme:
a magnesium ion battery electrolyte with a high electrochemical window, which comprises an organic solvent, a magnesium salt electrolyte and quaternary ammonium salt; the organic solvent is one or a mixture of more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tetrahydrofuran; the magnesium salt electrolyte is Mg (TFSI) 2 、Mg(OTf) 2 、MgCl 2 And AlCl 3 、Mg(BH 4 ) 2 、Mg[B(hfip) 4 ] 2 One or more of MgBOR; the quaternary ammonium salt has a general formula of N + (R 1 R 2 R 3 R 4 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein R is 1 、R 2 、R 3 、R 4 One or more of straight chain or branched chain with carbon number of 1-10.
The molar concentration of the magnesium salt in the organic solvent is 0.1mol/L to 0.5mol/L; the molar concentration of the quaternary ammonium salt in the organic solvent is 50 mmol/L-0.5 mol/L.
Preferably, the quaternary ammonium salt has the following structural general formula:
wherein X-is selected from BH 4 - 、F-、Cl-、Br - 、I - One or more of them.
The invention also provides a preparation method of the magnesium ion battery electrolyte with the high electrochemical window, which comprises the following steps:
step 1: preparing magnesium salt electrolyte and organic solvent according to claim 1, and mixing and stirring;
step 2: and adding quaternary ammonium salt under the stirring condition, and stirring for 10-30 hours to obtain the electrolyte.
Preferably, the preparation process is carried out at room temperature and filled with inert gas; meanwhile, the water content and the oxygen content in the reaction system are both less than 0.01ppm.
Preferably, the organic solvent is subjected to the following pretreatment: will be
The molecular sieve is heated to 300 ℃ and activated for 5 hours, then added into an organic solvent, and then sealed and preserved. Wherein the activation means that ∈>
The molecular sieve is heated to 300 ℃ for 5 hours and then added to the organic solvent while it is hot.
Preferably, the magnesium salt electrolyte is pretreated as follows: the magnesium salt electrolyte is sealed and preserved after being subjected to vacuum drying treatment for 24 hours at 60-200 ℃.
Preferably, the quaternary ammonium salt is pretreated as follows: the quaternary ammonium salt is sealed and preserved after being dried for 24 hours under the temperature of 60-100 ℃.
The invention also provides application of the electrolyte of the magnesium ion battery with the high electrochemical window, and application of the electrolyte in preparation of the rechargeable magnesium ion battery.
The invention also provides a magnesium ion battery which can be charged with the electrolyte of the magnesium ion battery with the high electrochemical window, and the magnesium ion battery contains the electrolyte.
Compared with the prior art, the invention has the following beneficial effects:
1. in the electrolyte, the magnesium salt electrolyte is preferably Mg (TFSI) 2 Such magnesium salts have moderate binding energy with ethereal solventsForce, thereby reducing free ether molecules in the electrolyte, and further reducing decomposition of ether molecules at high voltage; the anodic oxidation decomposition potential of the electrolyte on stainless steel reaches 4.8V (vs. Mg/Mg) 2+ ) Therefore, the magnesium ion battery can be matched with various high-voltage positive electrode materials, so that the magnesium ion battery can stably work under high voltage.
2. Anions in the electrolyte are favorable for avoiding the generation of a passivation film on the surface of Mg and BH 4 - Trace water and impurities can be removed; i - 、Br - Etc. can form Mg on the surface of Mg 2+ A conductive SEI film, thereby enabling Mg 2+ Reversible deposition/dissolution is enabled; at 0.1mA/cm 2 The electrolyte of the invention has a deposition dissolution efficiency of up to approximately 98% on stainless steel and an overpotential as low as 150mV.
3. The quaternary ammonium salt cations used as the additives in the electrolyte have high stable electrochemical performance on the negative reduction potential of magnesium, sodium and even lithium, so that the electrolyte has higher reduction stability on the surface of Mg, and can not be reduced in the working voltage range of a battery, and the electrolyte has better stability; meanwhile, the quaternary ammonium salt cations have shielding effect on Mg, and can utilize physical electrostatic field effect rather than chemical reaction products to inhibit dendritic dendrite from growing on the surface of the Mg electrode to induce Mg 2+ Uniform deposition, further prolonging the service life of the battery, at 0.5mA/cm 2 The assembled Mg// Mg symmetrical battery can be cycled for 700 more turns under the current of the battery, and the overpotential is not more than 400mV at maximum; at 5mA/cm 2 It also enables normal deposition/dissolution at high current densities.
4. The electrolyte can realize high-voltage circulation of the electrolyte by simply adjusting the dosage of the quaternary ammonium salt additive, and does not need to use the additive such as ionic liquid with higher cost or add various additives and adjust the proportion, thereby avoiding the disadvantages of high viscosity, high cost and the like; meanwhile, the preparation process of the electrolyte is simple, the preparation and synthesis time is short, and the reaction conditions are mild; meanwhile, no toxic gas is generated in the reaction process, and the method meets the requirements of green and environment protection, so that the method is easy to be used for large-scale industrial production.
5. The electrolyte of the invention does not adopt a common chlorine-containing compound, has no corrosiveness to the current collector and the battery shell, and can prolong the service life of the battery.
Drawings
FIG. 1 is a linear sweep voltammogram of the electrolyte prepared in example 1 of the present invention on different working electrodes.
FIG. 2 shows the electrolyte prepared in example 1 and comparative example of the present invention at 0.1mA/cm using stainless steel SS as a working electrode 2 Volume-voltage plot of deposition/dissolution at current density.
FIG. 3 shows the electrolyte prepared in example 1 and comparative example of the present invention at 0.1mA/cm using stainless steel SS as a working electrode 2 Reversible magnesium deposition/dissolution coulombic efficiency plot at current density.
Detailed Description
The invention will be further described with reference to the drawings and examples.
1. Examples and comparative examples
Example 1:
mg (TFSI) 2 The preparation raw materials and the method of the basic non-nucleophilic chargeable magnesium battery electrolyte specifically comprise:
(1) Pretreatment of the solvent: adding 3A molecular sieve activated for 5h at 300 ℃ into an organic ether solvent while the organic ether solvent is hot, and placing the mixture into a glove box for sealing and preserving.
(2) Pretreatment of magnesium salt electrolyte: mg (TFSI) 2 The magnesium salt is placed in a glove box for sealing and preservation after being subjected to vacuum drying treatment for 24 hours at 200 ℃.
(3) Pretreatment of quaternary ammonium salt additive: tetraethylammonium borohydride TEABH 4 Vacuum drying at 80deg.C for 24 hr, and sealing and storing in anhydrous and anaerobic glove box.
(4) And (3) preparing an electrolyte: all reactions were carried out under an anhydrous and oxygen-free inert atmosphere. 29.23g Mg (TFSI) 2 (0.5M) was slowly added to 100mL of glyme with stirring, and stirred for 2h; then 5.8g of tetraethylammonium borohydride (0.4M) was added with stirring, and the mixture was stirred for 24 hours, thereby obtaining a target electrolyte.
Table 1 the electrolytes of examples 2-6 were prepared in the following table (other drug pretreatment modes are the same as in example 1):
comparative example:
mg (TFSI) 2 The preparation raw materials and the preparation method of the comparative electrolyte of the non-nucleophilic chargeable magnesium battery specifically comprise the following steps:
(1) Pretreatment of the solvent: adding the heated mixture into an organic ether solvent while the mixture is hot, and heating the mixture at 300 ℃ for 5 hours
And (3) placing the molecular sieve in a glove box for sealing and preserving.
(2) Pretreatment of magnesium salt electrolyte: mg (TFSI) 2 The magnesium salt is placed in a glove box for sealing and preservation after being subjected to vacuum drying treatment for 24 hours at 200 ℃.
(3) And (3) preparing an electrolyte: all reactions were carried out under an anhydrous and oxygen-free inert atmosphere. 29.23g Mg (TFSI) 2 Slowly adding the electrolyte into 100mL of ethylene glycol dimethyl ether under stirring, and stirring for 24h to obtain the comparative electrolyte.
2. Performance comparison
The performance test method of the electrolyte is as follows (other examples test methods are the same)
a. Magnesium reversible deposition/dissolution and oxidative stability test
The magnesium reversible deposition/dissolution coulombic efficiency and oxidation stability test of the electrolyte are respectively tested by Cyclic Voltammetry (CV) and linear voltammetry (LSV), and the testing instrument is an electrochemical workstation of Shanghai Chenhua CHI 660. The test was performed by assembling CR2032 button cell, wherein the positive current collector was Stainless Steel (SS), the negative electrode was polished bright magnesium sheet, the separator was glass fiber membrane, and the assembled cell was left to stand at room temperature for more than 4 hours and then tested. The sweep speed of the cyclic voltammetry CV is 25mV/s, and the voltage range is-0.8V-2.0V; the voltage range of the LSV by the linear voltammetry scanning method is open-circuit voltage-6.0V, and the scanning speed is 25mV/s.
b. Coulombic efficiency test of reversible deposition/dissolution performance of magnesium
The reversible deposition/dissolution performance coulombic efficiency of the electrolyte is tested by constant current charge-discharge (CP), and the testing instrument is a Wuhan blue electric charge-discharge tester. The test was performed by assembling CR2032 button cell, wherein the positive current collector was Stainless Steel (SS), aluminum foil (Al), molybdenum foil (Mo), the negative electrode was polished magnesium sheet, the separator was glass fiber membrane, and the assembled cell was left to stand at room temperature for more than 4 hours and then tested. The charge-discharge test CP had a discharge time of 30min, a charge cut-off voltage of 2V, and a current density of 0.1mA/cm 2 ～0.5mA/cm 2 。
c. Polarization performance test
The polarization performance of the electrolyte is tested by constant current charge and discharge (CP), and the testing instrument is a Wohan blue electric charge and discharge tester. The test is carried out by assembling CR2032 button Mg// Mg symmetrical battery, wherein, the anode and the cathode adopt polished smooth magnesium sheets (Mg), and the assembled battery is kept stand for more than 4 hours at room temperature for further testing. The charge and discharge test current is 0.05mA/cm 2 ～5mA/cm 2 。
Example 1 the results obtained by the test procedure described above are as follows:
with stainless steel SS as the working electrode, the deposition overpotential of the electrolyte was as low as-300 mV, the dissolution overpotential was 180mV, and the overpotential was low (fig. 1). Electrochemical stable potential (vs. Mg/Mg of electrolyte on stainless steel, aluminum foil, molybdenum foil, copper foil, nickel foil and carbon cloth 2+ ) The electrochemical windows were higher at 4.6V, 4.0V, 3.6V, 3.0V and 3.0V, respectively (fig. 2). Stainless steel is used as a working electrode, and electrolyte is 0.5mA/cm 2 The average deposition/dissolution efficiency for 100 cycles at current density of (2) was 98% (fig. 3). At 0.5mA/cm 2 The initial polarization potential is as low as 180mV, the polarization potential after 700 circles is not more than 300mV, and the overpotential is not obviously increased.
The electrochemical properties associated with comparative example and example 1 are shown in the following table. The electrochemical window on Stainless Steel (SS) is also high, up to 4.2V, but its deposition overpotential is as high as-1.68V, its dissolution overpotential is as high as 1.80V, and the deposition dissolution efficiency is only about 15.4%, i.e. short circuit after about 100 cycles, its electrochemical performance is far lower than that of example 1 (fig. 2, 3). At different current densities (0.1 mA/cm) 2 、0.5mA/cm 2 、1mA/cm 2 ) The overpotential of the two were compared, and the overpotential of example 1 was 0.18V, 0.20V, 0.21mV; the overpotential of the comparative examples was 2.01V, 2.20V, 2.30V, respectively. At 0.5mA cm -2 At current density, the Mg// Mg symmetrical cell cycle overpotential is up to above 2.0V and short circuit failure occurs only with no more than 200 cycles. From this, it can be seen that the performance of example 1 in all aspects is due to the comparative example.
TABLE 2
| Example 1 | Performance data | Comparative example | Performance data |
| Electrochemical window/V (SS) | 4.6 | Electrochemical window/V (SS) | 4.2 |
| Deposition dissolution efficiency/% (SS) | 97.6 | Deposition dissolution efficiency/% (SS) | 16 |
| overpotential/V (0.1 mA cm) -2 ) | 0.15 | overpotential/V (0.1 mA cm) -2 ) | 2.0 |
| overpotential/V (0.5 mA cm) -2 ) | 0.18 | overpotential/V (0.5 mA cm) -2 ) | 2.2 |
| overpotential/V (2 mAcm) -2 ) | 0.21 | overpotential/V (2 mA cm) -2 ) | 2.3 |
The electrochemical performance test results show that the electrolyte has the obvious advantages of wide electrochemical window, higher magnesium deposition-dissolution efficiency, smaller overpotential, good cycle stability and capability of working under high current density.
Finally, examples 2 to 6 were subjected to electrochemical performance tests in the same manner as in example 1, and the results are shown in Table 3 below. Obviously, the electrolyte provided by the invention has the performances of wide electrochemical window, higher deposition/dissolution efficiency, low overpotential and the like.
TABLE 3 Table 3
| Examples | Electrochemical window (SS)/V | Deposition/dissolution efficiency (SS)/% | overpotential/ |
| 2 | 4.5 | 95 | 0.20 |
| 3 | 4.4 | 98 | 0.15 |
| 4 | 4.2 | 97 | 0.20 |
| 5 | 3.8 | 94 | 0.30 |
| 6 | 3.5 | 92 | 0.35 |
In conclusion, the invention aims at the problem that the magnesium ion battery electrolyte in the prior art cannot be suitable for high voltage, and realizes high voltage resistant Mg (TFSI) by regulating the concentration ratio of the quaternary ammonium salt additive 2 And (3) a base electrolyte. The electrolyte has the advantages of wide electrochemical window, higher deposition/dissolution efficiency, low overpotential, simple preparation and low cost. In addition, the electrolyte is free of corrosive ionsThe components can not corrode the current collector and the battery shell, and the service life of the battery is prolonged. In short, the electrolyte has good commercialization prospect.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the technical solution, and those skilled in the art should understand that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the present invention, and all such modifications and equivalents are included in the scope of the claims.
Claims (9)
1. The magnesium ion battery electrolyte with the high electrochemical window is characterized by comprising an organic solvent, a magnesium salt electrolyte and quaternary ammonium salt; the organic solvent is one or a mixture of more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tetrahydrofuran; the magnesium salt electrolyte is Mg (TFSI) 2 、Mg(OTf) 2 、MgCl 2 And AlCl 3 、Mg(BH 4 ) 2 、Mg[B(hfip) 4 ] 2 One or more of MgBOR; the quaternary ammonium salt has a general formula of N + (R 1 R 2 R 3 R 4 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein R is 1 、R 2 、R 3 、R 4 One or more selected from straight chain or branched chain with carbon number of 1-10;
the molar concentration of the magnesium salt in the organic solvent is 0.1mol/L to 0.5mol/L; the molar concentration of the quaternary ammonium salt in the organic solvent is 50 mmol/L-0.5 mol/L.
2. The high electrochemical window magnesium ion battery electrolyte according to claim 1, wherein the quaternary ammonium salt has the structural formula:
wherein X is - Selected from BH 4 - 、F-、Cl - 、Br - 、I - One of (a)One or more kinds.
3. The preparation method of the magnesium ion battery electrolyte with the high electrochemical window is characterized by comprising the following steps of:
step 1: preparing magnesium salt electrolyte and organic solvent according to claim 1, and mixing and stirring;
step 2: and adding quaternary ammonium salt under the stirring condition, and stirring for 10-30 hours to obtain the electrolyte.
4. A method for preparing the high electrochemical window magnesium ion battery electrolyte according to claim 3, wherein the preparation method is performed at room temperature and filled with inert gas; meanwhile, the water content and the oxygen content in the reaction system are both less than 0.01ppm.
5. A method for preparing a high electrochemical window magnesium ion battery electrolyte according to claim 3, wherein the organic solvent is subjected to the following pretreatment:
will be
The molecular sieve is heated to 300 ℃ and activated for 5 hours, then added into an organic solvent, and then sealed and preserved.
6. A method for preparing a magnesium ion battery electrolyte with a high electrochemical window according to claim 3, wherein the magnesium salt electrolyte is subjected to the following pretreatment:
the magnesium salt electrolyte is sealed and preserved after being subjected to vacuum drying treatment for 24 hours at 60-200 ℃.
7. The method for preparing the high electrochemical window magnesium ion battery electrolyte according to claim 3, wherein the quaternary ammonium salt is subjected to the following pretreatment:
the quaternary ammonium salt is sealed and preserved after being dried for 24 hours under the temperature of 60-100 ℃.
8. Use of an electrolyte for a magnesium ion battery with a high electrochemical window, characterized in that the use of the electrolyte according to any one of claims 1-2 for the preparation of a rechargeable magnesium ion battery.
9. A magnesium ion battery with a high electrochemical window magnesium ion battery electrolyte, characterized in that the magnesium ion battery comprises the electrolyte according to any one of claims 1-2.
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