CN114583294B - Solid-liquid mixed electrolyte interface additive combination, lithium metal battery and preparation method - Google Patents
Solid-liquid mixed electrolyte interface additive combination, lithium metal battery and preparation method Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 99
- 239000000654 additive Substances 0.000 title claims abstract description 81
- 230000000996 additive effect Effects 0.000 title claims abstract description 72
- 239000007788 liquid Substances 0.000 title claims abstract description 31
- 239000003792 electrolyte Substances 0.000 title claims abstract description 17
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims abstract description 51
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 42
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 40
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 40
- 239000002904 solvent Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 13
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 10
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 17
- 238000007600 charging Methods 0.000 claims description 17
- 238000007599 discharging Methods 0.000 claims description 15
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 13
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 10
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 8
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 7
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 7
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 7
- LZDKZFUFMNSQCJ-UHFFFAOYSA-N 1,2-diethoxyethane Chemical compound CCOCCOCC LZDKZFUFMNSQCJ-UHFFFAOYSA-N 0.000 claims description 6
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 238000005538 encapsulation Methods 0.000 claims description 4
- 238000000605 extraction Methods 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 4
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 claims description 3
- VTHRQKSLPFJQHN-UHFFFAOYSA-N 3-[2-(2-cyanoethoxy)ethoxy]propanenitrile Chemical compound N#CCCOCCOCCC#N VTHRQKSLPFJQHN-UHFFFAOYSA-N 0.000 claims description 3
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 3
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 3
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims description 3
- WXNUAYPPBQAQLR-UHFFFAOYSA-N B([O-])(F)F.[Li+] Chemical compound B([O-])(F)F.[Li+] WXNUAYPPBQAQLR-UHFFFAOYSA-N 0.000 claims description 2
- 229910001290 LiPF6 Inorganic materials 0.000 claims 1
- ZJPPTKRSFKBZMD-UHFFFAOYSA-N [Li].FS(=N)F Chemical compound [Li].FS(=N)F ZJPPTKRSFKBZMD-UHFFFAOYSA-N 0.000 claims 1
- 150000002148 esters Chemical class 0.000 claims 1
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 claims 1
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 claims 1
- 230000008569 process Effects 0.000 abstract description 9
- 238000010438 heat treatment Methods 0.000 abstract description 3
- 210000004027 cell Anatomy 0.000 description 14
- 229910013870 LiPF 6 Inorganic materials 0.000 description 6
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 150000002170 ethers Chemical class 0.000 description 4
- 229910010941 LiFSI Inorganic materials 0.000 description 3
- 239000003660 carbonate based solvent Substances 0.000 description 3
- 210000001787 dendrite Anatomy 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- 229910013188 LiBOB Inorganic materials 0.000 description 1
- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- OKVJWADVFPXWQD-UHFFFAOYSA-N difluoroborinic acid Chemical compound OB(F)F OKVJWADVFPXWQD-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000004210 ether based solvent Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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
- H01M10/052—Li-accumulators
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a solid-liquid mixed electrolyte interface additive combination, a lithium metal battery and a preparation method, wherein the solid-liquid mixed electrolyte interface additive combination comprises two different groups of interface additives, the interface additive 1 is a liquid composed of high-concentration lithium salt, ether solvent and lithium nitrate, the concentration of the high-concentration lithium salt is 2-5 mol/L, the interface additive 2 is a carbonate liquid of low-concentration lithium salt, and the concentration of the concentration lithium salt is 0.1-0.4 mol/L; the preparation method of the lithium metal battery comprises two stages, wherein the interface additive 1 is injected in the first stage, low-voltage low-current charge and discharge is carried out, so that lithium nitrate is reduced at a negative electrode to form an SEI film rich in Li 3 N, the interface additive 2 is injected in a vacuum cabin after heating and then high-voltage high-current charge and discharge are carried out for the second time, finally, high-voltage stable ultrathin CEI is formed on the surface of a positive electrode, and liquid consumed in the process of forming the SEI film and extracted in the vacuum cabin is replaced, so that the lithium metal battery has better cycle performance under high voltage.
Description
Technical Field
The invention relates to a lithium battery technology, in particular to a solid-liquid mixed electrolyte interface additive combination, a preparation method of a lithium metal battery and the lithium metal battery.
Background
Lithium metal batteries have been receiving attention from the academia and industry as a next-generation battery technology. However, lithium deposition on the surface of a lithium metal electrode is difficult to be kept uniform in the use process of the lithium metal battery, so that lithium dendrite is extremely easy to generate, and serious safety accidents are caused. Therefore, a solid-state battery technology is adopted, and a layer of SEI film which is uniform and stable and ensures electrochemical performance is constructed on the surface of lithium metal, so that the SEI film is the best way to solve the problem. Although the adoption of the high-concentration ether electrolyte can be reported to improve the cycle performance of the lithium metal negative electrode, on one hand, the high concentration can increase the viscosity of the electrolyte, reduce the lithium ion conductivity and influence the low temperature and the rate performance of the battery; on the other hand, the ethers can be decomposed on the surface of the positive electrode at the voltage of more than 4.0V, so that the application of the ethers in high-voltage ternary or LCO and other positive electrode systems is limited.
Lithium nitrate and ethylene glycol dimethyl ether are often used in lithium sulfur batteries and liquid lithium metal batteries to form SEI films, and ether solvents represented by ethylene glycol dimethyl ether and lithium nitrate have the advantage of improving lithium deposition efficiency, however, in high-voltage lithium metal batteries, the compatibility of ether compounds with high-voltage positive electrodes is poor, and the problem of easy gas expansion caused by the use of saturated vapor pressure in soft package batteries is also present. In addition, lithium nitrate is an effective additive that can be reduced at lithium negative electrodes to form an SEI film rich in Li 3 N, but is difficult to be applied in a large amount due to its low solubility in carbonates.
Disclosure of Invention
The invention aims to solve the technical problem of providing a solid-liquid mixed electrolyte interface additive combination, a lithium metal battery and a preparation method, and the invention effectively solves the problem of low content of lithium nitrate in a conventional carbonate interface additive, also solves the problem of poor compatibility of an ether interface additive and a high-voltage positive electrode, and finally realizes the solid-liquid mixed electrolyte lithium metal battery with high cycle performance.
The technical scheme adopted for solving the technical problems is as follows:
The solid-liquid mixed electrolyte interface additive combination comprises two different groups of interface additives, wherein the battery interface additive 1 is liquid composed of high-concentration lithium salt, ether solvent and lithium nitrate, the concentration of the high-concentration lithium salt is 2-5 mol/L, the battery interface additive 2 is carbonate liquid of low-concentration lithium salt, and the concentration of the low-concentration lithium salt is 0.1-0.4 mol/L.
Preferably, the high concentration lithium salt in the battery interface additive 1 and the low concentration lithium salt in the battery interface additive 2 are one or more of LiPF 6 (lithium hexafluorophosphate), liBOB (lithium oxalato borate), lipfob (lithium oxalato difluoroborate), liBF 4 (lithium tetrafluoroborate), liFSI (lithium bis-fluoro-sulfonyl imide), liTFSI (lithium bis-trifluoro-methylsulfonyl imide).
Preferably, the concentration of lithium nitrate in the battery interface additive 1 is 0.05 to 0.3mol/L.
Preferably, the ether solvent is one or more of DME (ethylene glycol dimethyl ether), G2 (diethylene glycol dimethyl ether), G3 (triethylene glycol dimethyl ether), DENE (ethylene glycol bis (propionitrile) ether), DOL (1, 3-dioxolane), DEE (1, 2-diethoxyethane), FDEE (fluorinated 1, 2-diethoxyethane).
Preferably, the carbonate is one or more of DEC (diethyl carbonate), DMC (dimethyl carbonate), EMC (ethylmethyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate), VC (vinylene carbonate), PS (1, 3-propane sultone).
A preparation method of a lithium metal battery comprises the following steps:
First stage
1) The positive plate, the negative plate and the solid diaphragm are put into a shell to obtain a battery cell to be injected, and the battery interface additive 1 is injected into the battery cell and then is placed still;
2) Carrying out low-current charge and discharge at 0.05-0.1C, wherein the charge cut-off voltage is 3.5-3.9V, and then discharging to 2-20% SOC;
Second stage
3) Under the protection of argon, opening the battery cell after charging and discharging in the first stage, and transferring the battery cell into a vacuum oven for baking;
4) Injecting the battery interface additive 2 into the vacuum baked battery core, standing, sealing, charging and discharging again by using a current of 0.2-0.5 ℃, wherein the charging cut-off voltage is 4.0-4.3V, and discharging to 0% SOC;
5) And (3) after air extraction and encapsulation, obtaining the solid-liquid mixed electrolyte lithium metal solid-state battery with high cycle performance.
Preferably, in the step 3), the temperature of the vacuum oven is 50 to 70 ℃, the pressure is-0.1 MPa, and the baking time is 6 to 10 hours.
A lithium metal battery is prepared by adopting the preparation method of the lithium metal battery.
Compared with the prior lithium metal battery technology, the solid-liquid mixed electrolyte interface additive combination, the lithium metal battery and the preparation method have the advantages that:
(1) A lithium metal battery with mixed solid-liquid electrolyte is characterized in that on one hand, the safety performance of the battery is improved by utilizing a solid diaphragm, on the other hand, the solid-solid interface performance is improved by utilizing an interface additive, a stable SEI layer is formed on the surface of lithium metal, and the critical current, high-rate charging and cycle performance of a lithium metal cathode are improved.
(2) The invention fully exerts the respective advantages by combining two completely different interface additives, solves the application problem of ether interface additives in lithium batteries by utilizing the addition and removal of different stages and the charge-discharge cut-off voltage at different stages, improves the compatibility problem of positive electrodes and interface additives, solves the problem of indissolvable lithium nitrate in conventional carbonate interface additives, and finally obtains the lithium metal battery with high cycle performance.
(3) The lithium salt concentration ratio of the two interface additives adopted by the invention is optimized, so that a stable and uniform SEI layer is formed on the surface of lithium metal in the first stage charge and discharge process, and after the second stage treatment, the combination of the solvent-free lithium salt remained in the first stage and a small amount of lithium salt added in the second stage not only satisfies the normal lithium ion transmission, but also avoids the problems of viscosity, solid-liquid mixed electrolyte lithium metal battery multiplying power, poor low-temperature performance and the like caused by overhigh lithium salt concentration.
(4) According to the invention, the charge-discharge cut-off voltage and the corresponding interface additive types are cooperated, so that the high-content lithium nitrate in the low-voltage low-current interface additive 1 in the first stage is reduced at the negative electrode to form an SEI film rich in Li 3 N, the ether solvent is evaporated and extracted by heating in the vacuum cabin in the second stage, and then the high-voltage high-current charge-discharge is carried out in the second stage, at the moment, the interface additive 2 forms an ultrathin CEI stable in high voltage resistance on the surface of the positive electrode, and the consumption in the SEI film forming process and the liquid extracted in the vacuum cabin are supplemented, so that the lithium metal battery has better cycle performance under high voltage.
(5) The ether interface additive is added preferentially, so that the defects of strong volatility, high saturated vapor pressure and the like of ethers are converted into advantages, the ether solvent can be completely removed at a lower temperature in a shorter time when vacuum baking is performed under the opening of the second-stage battery cell, and the possibility of oxidization of a lithium metal anode or damage of SEI structure and components is reduced.
(6) By controlling the concentration of lithium nitrate in the first-stage interface additive, the method not only meets the amount required by the first film-forming Li 3 N reaction of the lithium metal anode, but also can avoid precipitation in the second-stage solvent replacement process caused by excessive lithium nitrate.
(7) The charge quantity of the battery cell after the first stage is matched with the second stage baking process, so that the lithium metal dendrite elimination effect is achieved, the uneven surface generated by uneven nucleation of the lithium metal in the initial stage of charge deposition becomes smoother in the high-temperature process without solvent, and the unexpected finding is favorable for improving the cycle performance.
Detailed Description
The present invention is described in further detail below with reference to examples.
The solid-liquid mixed electrolyte interface additive combination comprises two different groups of interface additives, wherein the battery interface additive 1 is liquid composed of high-concentration lithium salt, ether solvent and lithium nitrate, and the concentration of the high-concentration lithium salt is 2-5 mol/L, preferably 2.2mol/L, 2.5mol/L, 2.8mol/L, 3mol/L, 3.5mol/L, 4mol/L, 4.5mol/L and 4.8mol/L. The battery interface additive 2 is a carbonate liquid of low-concentration lithium salt, and the concentration of the low-concentration lithium salt is 0.1-0.4 mol/L, preferably 0.12mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.38 mol/L.
Specifically, the high-concentration lithium salt in the battery interface additive 1 and the low-concentration lithium salt in the battery interface additive 2 are each one or more of LiPF 6 (lithium hexafluorophosphate), liBOB (lithium dioxaborate), lipfob (lithium difluoroborate), liBF 4 (lithium tetrafluoroborate), liFSI (lithium bis-fluorosulfonyl imide), liTFSI (lithium bis-trifluoromethylsulfonyl imide).
The concentration of lithium nitrate in the battery interface additive 1 is 0.05 to 0.3mol/L, preferably 0.08mol/L, 0.1mol mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.28mol/L.
The ether solvent is one or more of DME (ethylene glycol dimethyl ether), G2 (diethylene glycol dimethyl ether), G3 (triethylene glycol dimethyl ether), DENE (ethylene glycol bis (propionitrile) ether), DOL (1, 3-dioxolane), DEE (1, 2-diethoxyethane) and FDEE (fluorinated 1, 2-diethoxyethane).
The carbonate is one or more of DEC (diethyl carbonate), DMC (dimethyl carbonate), EMC (methyl ethyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate), VC (vinylene carbonate) and PS (1, 3-propane sultone).
A preparation method of a lithium metal battery is characterized in that: the method comprises the following steps:
First stage
1) The positive plate, the negative plate and the solid diaphragm are put into a shell to obtain a battery cell to be injected, and the battery interface additive 1 is injected into the battery cell and then is placed still;
2) Charging with small current of 0.05-0.1C, preferably 0.06C, 0.07C, 0.08C, 0.09C, and charging cut-off voltage of 3.5-3.9V, preferably 3.6V, 3.7V, 3.8V, and discharging to 2-20% SOC, preferably 4% SOC, 8% SOC, 10% SOC, 15% SOC;18% soc;
Second stage
3) Under the protection of argon, opening the battery cell after charging and discharging in the first stage, and transferring the battery cell into a vacuum oven for baking; the temperature of the vacuum oven is 50-70 ℃, preferably 52 ℃, 55 ℃, 58 ℃,60 ℃, 65 ℃, 68 ℃, the pressure is-0.1 MPa, the baking time is 6-10 hours, preferably 6.5 hours, 7 hours, 8 hours, 9 hours and 9.5 hours;
4) Injecting the battery interface additive 2 into the vacuum baked battery core, standing, sealing, and charging and discharging again by using a current of 0.2-0.5C, preferably 0.25C, 0.3C, 0.35C, 0.4C and 0.45C, wherein the charging cut-off voltage is 4.0-4.3V, and discharging to 0% SOC;
5) And (3) after air extraction and encapsulation, obtaining the solid-liquid mixed electrolyte lithium metal solid-state battery with high cycle performance.
The preparation method of the lithium metal battery comprises two stages, wherein the first stage is to inject an interface additive formula 1, perform low-voltage low-current charge and discharge, enable lithium nitrate to be reduced at a negative electrode to form an SEI film rich in Li 3 N, the second stage is to evaporate and extract an ether solvent through heating in a vacuum cabin, inject a battery interface additive 2, perform second high-voltage high-current charge and discharge, finally form high-voltage stable ultrathin CEI on the surface of a positive electrode, supplement liquid consumed in the process of forming the SEI film and extracted in the vacuum cabin, and finally enable the lithium metal battery to obtain better cycle performance.
Example 1,
A lithium metal battery prepared by the steps of:
First stage
1) The method comprises the steps of putting a positive plate, a negative plate and a solid diaphragm into a shell to obtain a battery cell to be injected, injecting a battery interface additive 1 into the battery cell, and standing, wherein the battery interface additive 1 is a liquid formed by mixing high-concentration lithium salt, ether solvent and lithium nitrate, the type of the high-concentration lithium salt is LiPF 6 (lithium hexafluorophosphate), the concentration is 3mol/L, the ether solvent is DME (ethylene glycol dimethyl ether), and the concentration of the lithium nitrate is 0.2mol/L;
2) Performing small-current charging at 0.08C, with a charge cutoff voltage of 3.8V, and then performing discharging to 15% SOC;
Second stage
3) Under the protection of argon, opening the battery cell after charging and discharging in the first stage, and transferring the battery cell into a vacuum oven for baking; the temperature of the vacuum oven is 65 ℃, the pressure is-0.1 MPa, and the baking time is 8 hours;
4) Injecting the battery interface additive 2 into the vacuum baked battery core, standing, sealing, charging and discharging again by using a current of 0.4 ℃, wherein the charge cut-off voltage is 4.2V, and discharging to 0% SOC; wherein the type of the low-concentration lithium salt of the carbonate liquid of the battery interface additive 2 is LiPF 6 (lithium hexafluorophosphate), the concentration is 0.2mol/L, and the carbonate solvent is DMC and FEC which are mixed according to the volume ratio of 1:1;
5) And (3) after air extraction and encapsulation, obtaining the solid-liquid mixed electrolyte lithium metal solid-state battery with high cycle performance.
EXAMPLE 2,
A lithium metal battery was distinguished from example 1 in that the concentration of the high concentration lithium salt in the battery interface additive 1 was 2mol/L.
EXAMPLE 3,
A lithium metal battery was distinguished from example 1 in that the concentration of the high concentration lithium salt in the battery interface additive 1 was 5mol/L.
EXAMPLE 4,
A lithium metal battery is different from example 1 in that the kind of high concentration lithium salt in the battery interface additive 1 is LiFSI.
EXAMPLE 5,
A lithium metal battery is different from example 1 in that the kind of high concentration lithium salt in the battery interface additive 1 is LiPF 6 and LiFSI mixed in a 1:1 molar ratio.
EXAMPLE 6,
A lithium metal battery is different from example 1 in that the kind of high concentration lithium salt in the battery interface additive 1 is LiPF 6 and lipfob mixed in a 1:1 molar ratio.
EXAMPLE 7,
A lithium metal battery differs from example 1 in that the ether solvent in the battery interface additive 1 is G2.
EXAMPLE 8,
A lithium metal battery differs from example 1 in that the ether solvent in the battery interface additive 1 is a mixture of G2 and DME in a 1:1 volume ratio.
EXAMPLE 9,
A lithium metal battery differs from example 1 in that the ether solvent in the battery interface additive 1 is DEE.
EXAMPLE 10,
A lithium metal battery was distinguished from example 1 in that the concentration of lithium nitrate in the battery interface additive 1 was 0.05mol/L.
EXAMPLE 11,
A lithium metal battery was distinguished from example 1 in that the concentration of lithium nitrate in the battery interface additive 1 was 0.3mol/L.
EXAMPLE 12,
A lithium metal battery was distinguished from example 1 in that the concentration of the low concentration lithium salt in the battery interface additive 2 was 0.1mol/L.
EXAMPLE 13,
A lithium metal battery was distinguished from example 1 in that the concentration of the low concentration lithium salt in the battery interface additive 2 was 0.4mol/L.
EXAMPLE 14,
A lithium metal battery differs from example 1 in that the kind of low concentration lithium salt in the battery interface additive 2 is LiBOB.
EXAMPLE 15,
A lithium metal battery differs from example 1 in that the kind of low concentration lithium salt in the battery interface additive 2 is lidaob.
EXAMPLE 16,
A lithium metal battery is different from example 1 in that the kind of low concentration lithium salt in the battery interface additive 2 is mixed with LiFSI and lifob in a molar ratio of 1:1.
EXAMPLE 17,
A lithium metal battery differs from example 1 in that the carbonate-based solvent in the battery interface additive 2 is DEC and FEC mixed in a volume ratio of 1:1.
EXAMPLE 18,
A lithium metal battery differs from example 1 in that the carbonate-based solvent in the battery interface additive 2 is DMC and EC mixed in a 1:1 volume ratio.
EXAMPLE 19,
A lithium metal battery is different from example 1 in that carbonate-based solvent in the battery interface additive 2 is mixed with EMC and FEC in a volume ratio of 1:1.
EXAMPLE 20,
A lithium metal battery differs from example 1 in that the charging current in step 2) is 0.05C.
EXAMPLE 21,
A lithium metal battery differs from example 1 in that the charging current in step 2) is 0.1C.
EXAMPLE 22,
A lithium metal battery differs from example 1 in that in step 2) the cut-off voltage is 3.5V.
EXAMPLE 23,
A lithium metal battery differs from example 1 in that in step 2) the cut-off voltage is 3.9V.
EXAMPLE 24,
A lithium metal battery differs from example 1 in that in step 2) the battery state of charge SOC is 2%.
EXAMPLE 25,
A lithium metal battery differs from example 1 in that in step 2) the battery is charged to a state of charge SOC of 20%.
EXAMPLE 26,
A lithium metal battery differs from example 1 in that the baking temperature in step 3) is 50 ℃.
EXAMPLE 27,
A lithium metal battery differs from example 1 in that the baking temperature in step 3) is 70 ℃.
EXAMPLE 28,
A lithium metal battery differs from example 1 in that the baking time in step 3) is 6 hours.
EXAMPLE 29,
A lithium metal battery differs from example 1 in that the baking time in step 3) is 10 hours.
EXAMPLE 30,
A lithium metal battery differs from example 1 in that in step 4) charging is performed using a current of 0.2C.
EXAMPLE 31,
A lithium metal battery differs from example 1 in that in step 4) charging is performed using a current of 0.5C.
EXAMPLE 32,
A lithium metal battery differs from example 1 in that the cut-off voltage in step 4) is 4V.
EXAMPLE 33,
A lithium metal battery differs from example 1 in that the cut-off voltage in step 4) is 4.3V.
Comparative example 1,
The lithium metal battery comprises a positive plate, a negative plate, a PP diaphragm and liquid, wherein the positive plate is made of nickel-cobalt-manganese ternary material, specifically NCM622, the negative plate is made of lithium metal, the thickness of the lithium metal is 50 mu m, the liquid is 1MLiPF 6/FEC-EMC, and the battery capacity is 3Ah.
Comparative example 2,
The lithium metal battery comprises a positive plate, a negative plate, a PP diaphragm and an interface additive, wherein the positive plate is made of a nickel-cobalt-manganese ternary material, specifically NCM622, the negative plate is made of lithium metal, the thickness of the lithium metal is 50 mu m, the interface additive is an ether-containing lithium nitrate interface additive 1MLiPF 6+0.1MLiNO3/FEC-EMC-DME (1:1:1 volume ratio), and the battery capacity is 3Ah.
Cycle performance test
The testing method comprises the following steps: and (3) carrying out charge and discharge circulation on the lithium metal battery by adopting a charge rate of 0.33C/0.33C, and recording the circulation times of the battery and the change of the appearance of the battery after the circulation is finished when the capacity retention rate is 80%.
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By comparing comparative example 1 with examples 1 to 33, it can be seen that the addition of lithium nitrate greatly improves the battery cycle performance of the battery.
By comparing comparative example 2 with examples 1 to 33, it can be seen that the problems of battery swelling and poor cycle life caused by the direct addition of the ether solvent to the electrolyte solution are solved by the addition of the two interface additive combinations in two stages.
By comparing example 1 with examples 20-33, it can be seen that the battery interface performance can be improved and lithium dendrites can be eliminated by combining the charge amount of the first stage, the formation condition of the second stage and the baking process, thereby improving the cycle performance.
By comparing examples 1-19, it can be seen that by adjusting the composition of the two interfacial additives, a stable and uniform SEI film can be formed in the first stage of the battery, and a proper combination of lithium salts is added in the second stage to maintain the battery at normal ion transport.
By comparing examples 1, 10, 11, it can be seen that by controlling the concentration of lithium nitrate in the first stage interface additive, it is possible to ensure that sufficient lithium nitrate forms a film on the negative electrode to produce Li 3 N, and to avoid precipitation due to excessive lithium nitrate in the second stage, thereby affecting performance.
While the preferred embodiments of the present invention have been described in detail, it is to be clearly understood that the same may be varied in many ways by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A preparation method of a lithium metal battery is characterized in that: the method comprises the following steps:
First stage
1) The positive plate, the negative plate and the solid diaphragm are put into a shell to obtain a battery cell to be injected, and the battery interface additive 1 is injected into the battery cell and then is placed still;
2) Carrying out low-current charge and discharge at 0.05-0.1C, wherein the charge cut-off voltage is 3.5-3.9V, and then discharging to 2-20% SOC;
Second stage
3) Under the protection of argon, opening the charged and discharged battery cell in the first stage, and transferring the battery cell into a vacuum oven for baking, wherein the temperature of the vacuum oven is 50-70 ℃, the pressure is-0.1 MPa, and the baking time is 6-10 hours;
4) Injecting the battery interface additive 2 into the vacuum baked battery core, standing, sealing, and recharging and discharging by using a current of 0.2-0.5 ℃, wherein the charging cut-off voltage is 4.0-4.3V, and the discharging cut-off is 0% SOC;
5) The solid-liquid mixed electrolyte lithium metal solid-state battery with high cycle performance is obtained after air extraction and encapsulation;
The battery interface additive 1 is a liquid composed of high-concentration lithium salt, ether solvent and lithium nitrate, wherein the concentration of the high-concentration lithium salt is 2-5 mol/L, and the concentration of the lithium nitrate in the battery interface additive 1 is 0.05-0.3 mol/L; the battery interface additive 2 is carbonate liquid of low-concentration lithium salt, and the concentration of the low-concentration lithium salt is 0.1-0.4 mol/L;
the high-concentration lithium salt in the battery interface additive 1 and the low-concentration lithium salt in the battery interface additive 2 are one or more of LiPF6 (lithium hexafluorophosphate), liBOB (lithium dioxaborate), liDFOB (lithium difluoroborate), liBF4 (lithium tetrafluoroborate), liFSI (lithium difluorosulfimide) and LiTFSI (lithium bistrifluoromethylsulfonimide);
The ether solvent is one or more of DME (ethylene glycol dimethyl ether), G2 (diethylene glycol dimethyl ether), G3 (triethylene glycol dimethyl ether), DENE (ethylene glycol bis (propionitrile) ether), DOL (1, 3-dioxolane), DEE (1, 2-diethoxyethane) and FDEE (fluorinated 1, 2-diethoxyethane);
The carbonic ester is one or more of DEC (diethyl carbonate), DMC (dimethyl carbonate), EMC (methyl ethyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate) and VC (vinylene carbonate).
2. A lithium metal battery characterized in that: a lithium metal battery prepared by the preparation method of the lithium metal battery as claimed in claim 1.
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