CN114583294A - 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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- CN114583294A CN114583294A CN202210158229.2A CN202210158229A CN114583294A CN 114583294 A CN114583294 A CN 114583294A CN 202210158229 A CN202210158229 A CN 202210158229A CN 114583294 A CN114583294 A CN 114583294A
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 103
- 239000000654 additive Substances 0.000 title claims abstract description 87
- 230000000996 additive effect Effects 0.000 title claims abstract description 78
- 239000007788 liquid Substances 0.000 title claims abstract description 40
- 239000003792 electrolyte Substances 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title abstract description 9
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 39
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 39
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 35
- 238000007600 charging Methods 0.000 claims abstract description 25
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000007599 discharging Methods 0.000 claims abstract description 20
- 239000002904 solvent Substances 0.000 claims abstract description 16
- 238000000034 method Methods 0.000 claims abstract description 14
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 11
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 17
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 11
- 239000007787 solid Substances 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
- 229910001290 LiPF6 Inorganic materials 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
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-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
- 229910010941 LiFSI Inorganic materials 0.000 claims description 6
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 6
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 claims description 6
- 229910013188 LiBOB Inorganic materials 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 4
- 238000004806 packaging method and process 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
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 claims description 3
- 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 description 3
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims description 3
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 8
- 238000010438 heat treatment Methods 0.000 abstract description 3
- 239000003795 chemical substances by application Substances 0.000 abstract 1
- 230000001502 supplementing effect Effects 0.000 abstract 1
- 210000004027 cell Anatomy 0.000 description 17
- 230000008901 benefit Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000004210 ether based solvent Substances 0.000 description 4
- 150000002170 ethers Chemical class 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000003660 carbonate based solvent Substances 0.000 description 3
- 230000008021 deposition Effects 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
- 230000015572 biosynthetic process Effects 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 125000001033 ether group Chemical group 0.000 description 1
- 206010016766 flatulence Diseases 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- DEUISMFZZMAAOJ-UHFFFAOYSA-N lithium dihydrogen borate oxalic acid Chemical compound B([O-])(O)O.C(C(=O)O)(=O)O.C(C(=O)O)(=O)O.[Li+] DEUISMFZZMAAOJ-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000010998 test 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
- 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
Abstract
The invention discloses a solid-liquid mixed electrolyte interface additive combination, a lithium metal battery and a preparation method thereof, wherein the solid-liquid mixed electrolyte interface additive combination comprises two different component interface additives, wherein the interface additive 1 is a liquid composed of high-concentration lithium salt, an 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 low-concentration lithium salt is 0.1-0.4 mol/L; the preparation method of the lithium metal battery comprises two stages, wherein in the first stage, the interface additive 1 is injected to perform low-voltage low-current charging and discharging, so that lithium nitrate is reduced at a negative electrode to form Li-rich lithium3Heating the SEI film in a vacuum chamber in the second stage, and injecting interface to addAdding the agent 2, then carrying out secondary high-voltage large-current charging and discharging, finally forming high-voltage stable ultrathin CEI on the surface of the positive electrode, supplementing liquid consumed in the process of forming an SEI film and extracted from a vacuum chamber, and finally enabling the lithium metal battery to obtain 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 both academic and industrial fields as a next-generation battery technology. However, since lithium deposition on the surface of the lithium metal electrode is difficult to maintain uniformly during the use of the lithium metal battery, lithium dendrite is easily generated, thereby causing a serious safety accident. Therefore, it is the best approach to solve this problem to adopt solid-state battery technology and build a uniform and stable SEI film on the surface of lithium metal to ensure electrochemical performance. Although the cycle performance of the lithium metal negative electrode can be improved by adopting the high-concentration ether electrolyte, the high concentration can increase the viscosity of the electrolyte on one hand, reduce the conductivity of lithium ions and influence the low temperature and rate performance of the battery; on the other hand, ethers are decomposed on the surface of the positive electrode at the voltage of 4.0V or more, so that the application of the ethers in a high-voltage ternary or LCO positive electrode system 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, 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, ethers have poor compatibility with high-voltage positive electrodes, and the problem of easy flatulence caused by saturated vapor pressure in soft package batteries is also existed. In addition, lithium nitrate is an effective additive that can be reduced to form Li-rich lithium at the lithium negative electrode3N, but it is difficult to apply them in large amounts because of 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, effectively solves the problem of low content of lithium nitrate in the 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 by the invention for solving the technical problems is as follows:
a solid-liquid mixed electrolyte interface additive combination comprises two different component interface additives, wherein a battery interface additive 1 is a liquid composed of high-concentration lithium salt, an ether solvent and lithium nitrate, the concentration of the high-concentration lithium salt is 2-5 mol/L, a 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, the high concentration lithium salt in the battery interface additive 1 and the low concentration lithium salt in the battery interface additive 2 are both LiPF6(lithium hexafluorophosphate), LiBOB (lithium dioxalate borate), LiDFOB (lithium oxalyldifluoroborate), LiBF4(lithium tetrafluoroborate), LiFSI (lithium bis (fluorosulfonylimide)), and LiTFSI (lithium bis (trifluoromethylsulfonyl imide)).
Preferably, the concentration of lithium nitrate in the battery interface additive 1 is 0.05-0.3 mol/L.
Preferably, the ether solvent is one or more selected from DME (ethylene glycol dimethyl ether), G2 (diethylene glycol dimethyl ether), G3 (triethylene glycol dimethyl ether), done (ethylene glycol bis (propionitrile) ether), DOL (1, 3-dioxolane), DEE (1, 2-diethoxyethane), and FDEE (fluorinated 1, 2-diethoxyethane).
Preferably, the carbonate is one or more of DEC (diethyl carbonate), DMC (dimethyl carbonate), EMC (ethyl methyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate), VC (vinylene carbonate), PS (1, 3-propane sultone).
A method for preparing a lithium metal battery comprises the following steps:
first stage
1) Putting the positive plate, the negative plate and the solid diaphragm into a shell to obtain a battery cell to be injected with liquid, and standing after injecting the battery interface additive 1 into the battery cell;
2) charging and discharging at a low current of 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) Opening the battery cell after the first-stage charging and discharging under the protection of argon, and transferring the battery cell into a vacuum oven for baking;
4) injecting the battery interface additive 2 into the vacuum-baked battery cell, standing, sealing, and charging and discharging again by using a current of 0.2-0.5C, wherein the charge cut-off voltage is 4.0-4.3V, and the charge cut-off voltage is discharged to 0% SOC;
5) and after air exhaust and packaging, the solid-liquid mixed electrolyte lithium metal solid battery with high cycle performance is obtained.
Preferably, in the step 3), the temperature of the vacuum oven is 50-70 ℃, the pressure is-0.1 MPa, and the baking time is 6-10 hours.
A lithium metal battery is prepared by 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 mixed solid-liquid electrolyte lithium metal battery utilizes a solid diaphragm to improve the safety performance of the battery, and utilizes an interface additive to improve the performance of a solid-solid interface and form a stable SEI layer on the surface of lithium metal to improve the critical current, high-rate charging and cycle performance of a lithium metal cathode.
(2) The invention combines two completely different interface additives, fully exerts respective advantages, utilizes the addition and the removal of different stages and the charge-discharge cut-off voltage of different stages, solves the application problem of the ether interface additive in the lithium battery, improves the compatibility problem of the anode and the interface additive, simultaneously solves the problem caused by the difficult dissolution of the lithium nitrate in the conventional carbonate interface additive, and finally obtains the lithium metal battery of the solid-liquid mixed electrolyte with high cycle performance.
(3) The lithium salt concentration proportion of the two interface additives adopted by the invention is optimized, the sufficient, stable and uniform SEI layer can be formed on the surface of lithium metal in the first-stage charging and discharging process, and after the second-stage treatment, the combination of the solvent-free lithium salt remained in the first stage and the small amount of lithium salt added in the second stage meets the normal lithium ion transmission, and the problems of viscosity, poor multiplying power and low-temperature performance of a solid-liquid mixed electrolyte lithium metal battery and the like caused by overhigh lithium salt concentration are also avoided.
(4) The charge-discharge cut-off voltage adopted by the invention and the corresponding interface additive species are in synergistic effect, and finally the first-stage low-voltage low-current interface additive 1 with high content of lithium nitrate is reduced to form Li-rich Li at the negative electrode3And in the second stage, the ether solvent is evaporated and extracted by heating in a vacuum chamber, and then high-voltage large-current charging and discharging are carried out in the second stage, so that the interface additive 2 forms high-voltage-resistant stable ultrathin CEI on the surface of the positive electrode, the consumption in the process of forming the SEI film is supplemented, the liquid extracted from the vacuum chamber is replaced, and finally the lithium metal battery obtains better cycle performance under high voltage.
(5) The ether interface additive is preferentially added, 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 and in a shorter time when vacuum baking is carried out under the opening of the battery cell in the second stage, and the possibility of oxidation of the lithium metal negative electrode or damage of an SEI structure and components is reduced.
(6) By controlling the concentration of lithium nitrate in the interface additive in the first stage, the first film formation Li of the lithium metal negative electrode is satisfied3N is required, and precipitation in the second-stage solvent replacement process caused by excessive lithium nitrate can be avoided.
(7) According to the invention, the electric charge of the battery cell after the first stage is matched with the baking process of the second stage, so that the lithium metal dendritic crystal eliminating effect is achieved, unevenness generated by uneven nucleation of lithium metal in the initial stage of charge deposition becomes smoother and smoother through a high-temperature process without a solvent, and the improvement of the cycle performance is facilitated through unexpected discovery.
Detailed Description
The present invention will be described in further detail with reference to examples.
A solid-liquid mixed electrolyte interface additive combination comprises two different component interface additives, wherein a battery interface additive 1 is a liquid composed of high-concentration lithium salt, an ether solvent and lithium nitrate, 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 4.8 mol/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 both LiPF6(lithium hexafluorophosphate), LiBOB (lithium bis (oxalato) borate), LiDFOB (oxalato bis (fluoroborate)), LiBF4(lithium tetrafluoroborate), LiFSI (lithium bis (fluorosulfonylimide)), and LiTFSI (lithium bis (trifluoromethylsulfonyl imide)).
The concentration of lithium nitrate in the battery interface additive 1 is 0.05-0.3 mol/L, preferably 0.08mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L and 0.28 mol/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 (ethyl methyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate), VC (vinylene carbonate), PS (1, 3-propane sultone).
A method for preparing a lithium metal battery is characterized in that: the method comprises the following steps:
first stage
1) Putting the positive plate, the negative plate and the solid diaphragm into a shell to obtain a battery cell to be injected with liquid, and standing after injecting the battery interface additive 1 into the battery cell;
2) charging at a low current of 0.05-0.1C, preferably 0.06C, 0.07C, 0.08C, 0.09C, at a charge cut-off voltage of 3.5-3.9V, preferably 3.6V, 3.7V, 3.8V, and then discharging to 2-20% SOC, preferably 4% SOC, 8% SOC, 10% SOC, 15% SOC; 18% SOC;
second stage
3) Opening the battery cell after the first-stage charging and discharging under the protection of argon, 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 ℃ and 68 ℃, the pressure is-0.1 MPa, and 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 cell, 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, with a charge cut-off voltage of 4.0-4.3V, to 0% SOC;
5) and after air exhaust and packaging, the solid-liquid mixed electrolyte lithium metal solid battery with high cycle performance is obtained.
The preparation method of the lithium metal battery comprises two stages, wherein in the first stage, the interface additive formula 1 is injected, and low-voltage and low-current charging and discharging are carried out, so that lithium nitrate is reduced at a negative electrode to form a lithium-rich battery3And in the second stage, the ether solvent is evaporated and extracted by heating in a vacuum chamber, then the battery interface additive 2 is injected, and then secondary high-voltage large-current charging and discharging are carried out, so that high-voltage stable ultrathin CEI is finally formed on the surface of the anode, and liquid consumed in the process of forming the SEI film and extracted in the vacuum chamber is supplemented, so that the lithium metal battery can obtain better cycle performance.
Examples 1,
A lithium metal battery prepared by the steps of:
first stage
1) Putting the positive plate, the negative plate and the 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 mixed by high-concentration lithium salt, an ether solvent and lithium nitrate, and is a seed of the high-concentration lithium saltClass is LiPF6(lithium hexafluorophosphate) with the concentration of 3mol/L, DME (ethylene glycol dimethyl ether) as an ether solvent and 0.2mol/L of lithium nitrate;
2) charging with a small current of 0.08C and a charge cut-off voltage of 3.8V, and then discharging to 15% SOC;
second stage
3) Opening the battery cell after the first-stage charging and discharging under the protection of argon, 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 cell, standing, sealing, and charging and discharging again by using 0.4C current, wherein the charge cut-off voltage is 4.2V, and the charge cut-off voltage is 0% SOC; wherein the carbonate liquid of the battery interface additive 2 and the low-concentration lithium salt are LiPF6(lithium hexafluorophosphate) in a concentration of 0.2mol/L, the carbonate solvent being DMC and FEC mixed in a volume ratio of 1: 1;
5) and after air exhaust and packaging, the solid-liquid mixed electrolyte lithium metal solid battery with high cycle performance is obtained.
Examples 2,
A lithium metal battery differs from example 1 in that the concentration of the high-concentration lithium salt in the battery interface additive 1 is 2 mol/L.
Examples 3,
A lithium metal battery differs from example 1 in that the concentration of the high-concentration lithium salt in the battery interface additive 1 is 5 mol/L.
Examples 4,
A lithium metal battery differs from example 1 in that the species of the high concentration lithium salt in the battery interface additive 1 is LiFSI.
Examples 5,
A lithium metal battery is different from the battery of example 1 in that the kind of the high-concentration lithium salt in the battery interface additive 1 is LiPF6Mixed with LiFSI in a 1:1 molar ratio.
Examples 6,
A lithium metal battery, differing from example 1 in that the battery interfaceThe type of the high-concentration lithium salt in the additive 1 is LiPF6Mixed with LiDFOB in a 1:1 molar ratio.
Example 7,
A lithium metal battery, which is different from example 1 in that the ether-based solvent in the battery interface additive 1 is G2.
Example 8,
A lithium metal battery, which is different from example 1 in that the ether solvent G2 and DME were mixed in a 1:1 volume ratio in the battery interfacial additive 1.
Examples 9,
A lithium metal battery, which is different from example 1 in that the ether-based solvent in the battery interface additive 1 is DEE.
Examples 10,
A lithium metal battery was distinguished from example 1 in that the concentration of lithium nitrate in the battery interface additive 1 was 0.05 mol/L.
Examples 11,
A lithium metal battery was distinguished from example 1 in that the concentration of lithium nitrate in the battery interface additive 1 was 0.3 mol/L.
Examples 12,
A lithium metal battery differs from example 1 in that the concentration of the low-concentration lithium salt in the battery interface additive 2 is 0.1 mol/L.
Examples 13,
A lithium metal battery, differing from example 1 in that the concentration of the low concentration lithium salt in the battery interface additive 2 was 0.4 mol/L.
Examples 14,
A lithium metal battery differs from example 1 in that the low concentration lithium salt species in the battery interfacial additive 2 is LiBOB.
Examples 15,
A lithium metal battery differs from example 1 in that the type of low concentration lithium salt in the battery interface additive 2 is liddob.
Examples 16,
A lithium metal battery differs from example 1 in that the species of low concentration lithium salt in the battery interface additive 2 is LiFSI and liddob mixed in a molar ratio of 1: 1.
Examples 17,
A lithium metal battery differs from example 1 in that the carbonate-based solvent in battery interfacial additive 2 is DEC and FEC mixed in a 1:1 volume ratio.
Examples 18,
A lithium metal battery, which is different from example 1 in that the carbonate-based solvent of battery interfacial additive 2 is DMC and EC mixed in a 1:1 volume ratio.
Examples 19,
A lithium metal battery, which is different from example 1 in that the carbonate-based solvent in the battery interface additive 2 is EMC and FEC mixed in a 1:1 volume ratio.
Examples 20,
A lithium metal battery, which is different from example 1 in that the charging current in step 2) is 0.05C.
Examples 21,
A lithium metal battery, which is different from example 1 in that the charging current in step 2) is 0.1C.
Examples 22,
A lithium metal battery, which is different from example 1 in that the cut-off voltage in step 2) is 3.5V.
Examples 23,
A lithium metal battery, which is different from example 1 in that the cut-off voltage in step 2) is 3.9V.
Examples 24,
A lithium metal battery, differing from example 1 in that charging to a battery state of charge SOC of 2% in step 2).
Examples 25,
A lithium metal battery, differing from example 1 in that charging to a battery state of charge SOC of 20% in step 2).
Examples 26,
A lithium metal battery, which is different from example 1 in that the baking temperature in step 3) is 50 ℃.
Examples 27,
A lithium metal battery, which is different from example 1 in that the baking temperature in step 3) is 70 ℃.
Examples 28,
A lithium metal battery, which is different from example 1 in that the baking time in step 3) is 6 hours.
Examples 29,
A lithium metal battery, which is different from example 1 in that the baking time in step 3) is 10 hours.
Examples 30,
A lithium metal battery, which is different from example 1 in that the charging is performed using a current of 0.2C in step 4).
Examples 31,
A lithium metal battery, which is different from example 1 in that the charging is performed using a current of 0.5C in step 4).
Examples 32,
A lithium metal battery, which is different from example 1 in that the cut-off voltage in step 4) is 4V.
Examples 33,
A lithium metal battery, which is different from example 1 in that the cut-off voltage in step 4) is 4.3V.
Comparative examples 1,
The lithium metal battery comprises a positive plate, a negative plate, a PP diaphragm and liquid, 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, and the liquid is 1MLiPF6The battery capacity was 3Ah,/FEC-EMC.
Comparative examples 2,
The lithium metal battery comprises a positive plate, a negative plate, a PP diaphragm and an interface additive, wherein the positive material of the positive plate is a nickel-cobalt-manganese ternary material, specifically NCM622, the negative material of the negative plate is lithium metal, the thickness of the lithium metal is 50 mu m, and the interface additive is ether-containing lithium nitrate-containing interface additive 1MLiPF6+0.1MLiNO3The battery capacity was 3Ah for/FEC-EMC-DME (1:1:1 volume ratio).
Cycle performance test
The test method comprises the following steps: and (3) performing charge and discharge cycles on the lithium metal battery by adopting a charge rate of 0.33C/0.33C, and recording the cycle number of the battery and the change of the appearance of the battery after the cycle is finished when the capacity retention rate is 80%.
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 ether solvents to the electrolyte are solved by adding the combination of two interfacial additives in two stages.
By comparing the example 1 with the examples 20 to 33, it can be seen that the interface performance of the battery can be improved and the lithium dendrites can be eliminated by the combination of the charge amount in the first stage, the formation conditions in the second stage and the baking process, so that the cycle performance can be improved.
By comparing examples 1-19, it can be seen that the composition of the two interfacial additives can be adjusted to form a stable and uniform SEI film in the first stage of the battery, and the proper combination of lithium salts can be added in the second stage to maintain the normal ion transport of the battery.
By comparing examples 1, 10 and 11, it can be seen that sufficient lithium nitrate can be ensured to form a film on the negative electrode to generate Li by controlling the concentration of lithium nitrate in the first-stage interface additive3N, and avoids the performance influence caused by precipitation caused by excessive lithium nitrate in the second stage.
Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that modifications and variations of the present invention are possible to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A solid-liquid mixed electrolyte interface additive combination characterized by: the battery interface additive comprises two different components of interface additives, wherein the battery interface additive 1 is a liquid composed of high-concentration lithium salt, an ether solvent and lithium nitrate, the concentration of the high-concentration lithium salt is 2-5 mol/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.
2. The solid-liquid mixed electrolyte interface additive combination of claim 1, wherein: the high-concentration lithium salt in the battery interface additive 1 and the low-concentration lithium salt in the battery interface additive 2 are both LiPF6(lithium hexafluorophosphate), LiBOB (lithium bis (oxalato) borate), LiDFOB (oxalato bis (fluoroborate)), LiBF4(lithium tetrafluoroborate), LiFSI (lithium bis (fluorosulfonylimide)), and LiTFSI (lithium bis (trifluoromethylsulfonyl imide)).
3. The solid-liquid mixed electrolyte interface additive combination of claim 1, wherein: the concentration of lithium nitrate in the battery interface additive 1 is 0.05-0.3 mol/L.
4. The solid-liquid mixed electrolyte interface additive combination of claim 1, wherein: 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).
5. The solid-liquid mixed electrolyte interface additive combination of claim 1, wherein: the carbonate is one or more of DEC (diethyl carbonate), DMC (dimethyl carbonate), EMC (ethyl methyl carbonate), EC (ethylene carbonate), FEC (fluoroethylene carbonate), VC (vinylene carbonate) and PS (1, 3-propane sultone).
6. A method for preparing a lithium metal battery is characterized in that: the method comprises the following steps:
first stage
1) Putting the positive plate, the negative plate and the solid diaphragm into a shell to obtain a battery cell to be injected with liquid, and standing after injecting the battery interface additive 1 into the battery cell;
2) charging and discharging at a low current of 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) Opening the battery cell after the first-stage charging and discharging under the protection of argon, and transferring the battery cell into a vacuum oven for baking;
4) injecting the battery interface additive 2 into the vacuum-baked battery cell, standing, sealing, and charging and discharging again by using a current of 0.2-0.5C, wherein the charge cut-off voltage is 4.0-4.3V, and the discharge cut-off is 0% SOC;
5) and after air exhaust and packaging, the solid-liquid mixed electrolyte lithium metal solid battery with high cycle performance is obtained.
7. The method of manufacturing a lithium metal battery according to claim 6, wherein: in the step 3), the temperature of the vacuum oven is 50-70 ℃, the pressure is-0.1 MPa, and the baking time is 6-10 hours.
8. A lithium metal battery, characterized in that: the lithium metal battery manufactured by the method for manufacturing a lithium metal battery according to claim 6 or 7.
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