CN117558968A - Solid lithium ion battery based on double-layer electrolyte and additive and preparation method thereof - Google Patents
Solid lithium ion battery based on double-layer electrolyte and additive and preparation method thereof Download PDFInfo
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- CN117558968A CN117558968A CN202311601212.0A CN202311601212A CN117558968A CN 117558968 A CN117558968 A CN 117558968A CN 202311601212 A CN202311601212 A CN 202311601212A CN 117558968 A CN117558968 A CN 117558968A
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- electrolyte
- positive electrode
- zinc
- lithium
- additive
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 183
- 239000000654 additive Substances 0.000 title claims abstract description 64
- 230000000996 additive effect Effects 0.000 title claims abstract description 61
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 37
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 239000007787 solid Substances 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 239000011701 zinc Substances 0.000 claims abstract description 94
- 239000011737 fluorine Substances 0.000 claims abstract description 40
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 40
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 39
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 32
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 31
- 239000011159 matrix material Substances 0.000 claims abstract description 24
- 239000007774 positive electrode material Substances 0.000 claims abstract description 18
- 150000003751 zinc Chemical class 0.000 claims abstract description 12
- 239000007773 negative electrode material Substances 0.000 claims abstract description 6
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 51
- 229910052744 lithium Inorganic materials 0.000 claims description 51
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 47
- 239000010410 layer Substances 0.000 claims description 35
- 239000002033 PVDF binder Substances 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 26
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 26
- 239000002904 solvent Substances 0.000 claims description 18
- -1 zinc bis-fluorosulfonyl imide Chemical class 0.000 claims description 16
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 15
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 13
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 13
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 12
- 238000001704 evaporation Methods 0.000 claims description 12
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 12
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- 239000002131 composite material Substances 0.000 claims description 7
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- 239000010405 anode material Substances 0.000 claims description 6
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 6
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 4
- 239000002356 single layer Substances 0.000 claims description 4
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 claims description 4
- PMWGIVRHUIAIII-UHFFFAOYSA-N 2,2-difluoropropanoic acid Chemical compound CC(F)(F)C(O)=O PMWGIVRHUIAIII-UHFFFAOYSA-N 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 239000004743 Polypropylene Substances 0.000 claims description 3
- 238000004090 dissolution Methods 0.000 claims description 3
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- 229920001155 polypropylene Polymers 0.000 claims description 3
- 235000005074 zinc chloride Nutrition 0.000 claims description 3
- 239000011592 zinc chloride Substances 0.000 claims description 3
- 229910002804 graphite Inorganic materials 0.000 claims description 2
- 239000010439 graphite Substances 0.000 claims description 2
- 239000004417 polycarbonate Substances 0.000 claims description 2
- 229920000515 polycarbonate Polymers 0.000 claims description 2
- 229920005554 polynitrile Polymers 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 claims description 2
- 229960001763 zinc sulfate Drugs 0.000 claims description 2
- 229910000368 zinc sulfate Inorganic materials 0.000 claims description 2
- RXBXBWBHKPGHIB-UHFFFAOYSA-L zinc;diperchlorate Chemical compound [Zn+2].[O-]Cl(=O)(=O)=O.[O-]Cl(=O)(=O)=O RXBXBWBHKPGHIB-UHFFFAOYSA-L 0.000 claims description 2
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims 1
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims 1
- 150000003949 imides Chemical class 0.000 claims 1
- 230000001351 cycling effect Effects 0.000 abstract description 8
- 229910001512 metal fluoride Inorganic materials 0.000 abstract description 4
- 238000009792 diffusion process Methods 0.000 abstract description 3
- 230000014759 maintenance of location Effects 0.000 description 27
- 238000012360 testing method Methods 0.000 description 27
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 17
- 239000010949 copper Substances 0.000 description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 13
- 238000011056 performance test Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 239000002759 woven fabric Substances 0.000 description 9
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 6
- 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 description 6
- 150000001450 anions Chemical class 0.000 description 5
- 150000001768 cations Chemical class 0.000 description 5
- 239000005518 polymer electrolyte Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052723 transition metal Inorganic materials 0.000 description 4
- ZXMGHDIOOHOAAE-UHFFFAOYSA-N 1,1,1-trifluoro-n-(trifluoromethylsulfonyl)methanesulfonamide Chemical compound FC(F)(F)S(=O)(=O)NS(=O)(=O)C(F)(F)F ZXMGHDIOOHOAAE-UHFFFAOYSA-N 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000003993 interaction 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
- 238000002156 mixing Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 229910013872 LiPF Inorganic materials 0.000 description 2
- 101150058243 Lipf gene Proteins 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 239000007784 solid electrolyte Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229910021561 transition metal fluoride Inorganic materials 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229920006037 cross link polymer Polymers 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000004770 highest occupied molecular orbital Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004768 lowest unoccupied molecular orbital Methods 0.000 description 1
- PQIOSYKVBBWRRI-UHFFFAOYSA-N methylphosphonyl difluoride Chemical group CP(F)(F)=O PQIOSYKVBBWRRI-UHFFFAOYSA-N 0.000 description 1
- KTQDYGVEEFGIIL-UHFFFAOYSA-N n-fluorosulfonylsulfamoyl fluoride Chemical compound FS(=O)(=O)NS(F)(=O)=O KTQDYGVEEFGIIL-UHFFFAOYSA-N 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920000131 polyvinylidene Polymers 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- QEORIOGPVTWFMH-UHFFFAOYSA-N zinc;bis(trifluoromethylsulfonyl)azanide Chemical compound [Zn+2].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F.FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QEORIOGPVTWFMH-UHFFFAOYSA-N 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
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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)
- Electrochemistry (AREA)
- Engineering & Computer Science (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Dispersion Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention relates to a solid lithium ion battery based on double-layer electrolyte and additive and a preparation method thereof, wherein the solid lithium ion battery comprises a positive electrode material, a positive electrode side electrolyte, a medium, a negative electrode side electrolyte and a negative electrode material, the positive electrode material is coated with a zinc-containing additive on the surface of a positive electrode plate, the zinc-containing additive comprises zinc salt and fluorine-containing lithium salt, the positive electrode side electrolyte adopts double-layer electrolyte, and the double-layer electrolyte comprises matrix electrolyte and fluorine-containing electrolyte. Compared with the prior art, the invention effectively inhibits the drift diffusion of the metal fluoride and improves the high-voltage cycling stability of the battery.
Description
Technical Field
The invention belongs to the technical field of lithium-based secondary batteries, and relates to a solid-state lithium ion battery based on double-layer electrolyte and an additive and a preparation method thereof.
Background
The solid polymer electrolyte battery has the characteristics of high energy density and high safety. The polymer electrolyte in the solid polymer electrolyte battery needs to have the advantages of high flexibility, incombustibility, non-volatility, and good mechanical properties. Among them, polyethylene oxide (PEO) -based polymer electrolyte has the characteristics of easy film formation, easy dissolution of lithium salt and stability to lithium, but PEO-based polymer electrolyte has the problems of easy decomposition at high pressure, collapse of a positive electrode structure, and low electrochemical stability of a generated battery at high pressure. Therefore, by introducing inorganic or organic additives at the interface, constructing a positive electrode-electrolyte interface (CEI) film by in-situ film formation, a technical effect of protecting the positive electrode material from collapse can be obtained. However, the current battery with a CEI film-protecting anode still cannot realize stable circulation at high voltage of 4.5V and above, i.e. cannot form a CEI film with high voltage stability.
In order to form a CEI film with high voltage stability, patent CN113839092A discloses a doped positive metal salt-lithium salt composite additive and application thereof, and the transition metal cation additive is coated on the positive electrode to obtain the CEI film with high voltage stability, so that the stable cycle cut-off voltage of the battery is up to 4.4V.
However, subsequent studies have found that the transition metal fluoride CEI film is unstable during charge and discharge, and metal cations are likely to drift and diffuse into the PEO electrolyte along with charge and discharge, so that additive products cannot exist stably at the interface, and the battery cycle stability is impaired, and in order to ensure that transition metal cations exist stably at the interface between the positive electrode and the electrolyte, bulk improvement of the electrolyte is required.
Patent CN114243100A discloses a positive metal salt additive for constructing a positive interface film of a solid electrolyte and application thereof, wherein Bi for stably coating a positive electrode is adopted 3+ 、Ti 4+ 、Co 3+ 、Mn 4+ 、Zr 4+ 、Fe 3+ 、V 5+ And the like as the metal cation of the metal salt additive. Although the patent adopts the metal cation interface film to protect the lithium battery, the maximum voltage is 4.4V, and the patent cannot break through 4.5VHigh pressure.
Patent CN102939681a discloses an electrolyte for an electrochemical device, a method of preparing the electrolyte, and an electrochemical device comprising the electrolyte, the solid electrolyte comprising a complex consisting of: a plastic crystal matrix electrolyte doped with an ionic salt; and a network of uncrosslinked polymer and crosslinked polymer structure. However, the flexible electrolyte prepared by the patent does not adopt protection measures for the positive electrode material, and the battery lacks the capability of resisting high voltage.
Disclosure of Invention
The invention aims to overcome at least one defect in the prior art and provide a solid lithium ion battery based on a double-layer electrolyte and an additive and a preparation method thereof.
The aim of the invention can be achieved by the following technical scheme:
the invention provides a solid lithium ion battery based on double-layer electrolyte and additive, which comprises a positive electrode material, a positive electrode side electrolyte, a medium, a negative electrode side electrolyte and a negative electrode material, wherein the positive electrode material is prepared by coating a zinc-containing additive on the surface of a positive electrode plate, the zinc-containing additive comprises zinc salt and fluorine-containing lithium salt, and the zinc-containing additive is coated on the surface of the positive electrode plate to prepare a zinc positive electrode, so that the positive electrode structure is protected from collapsing under high voltage, the stability of a positive electrode-electrolyte interface is improved, and the zinc positive electrode comprises Zn in the charging and discharging process 2+ Occupying Li + The structure of the positive electrode in the zinc positive electrode is changed, the electrolyte at the positive electrode side adopts double-layer electrolyte, the double-layer electrolyte comprises matrix electrolyte and fluorine-containing electrolyte, the zinc-containing additive is protected from being coated on the positive electrode and is not diffused along with the electrolyte, and the positive electrode is protected by the combined action of the zinc-containing additive and the double-layer electrolyte.
Further, the zinc salt comprises zinc chloride (ZnCl) 2 ) Zinc nitrate (Zn (NO) 3 ) 2 ) Zinc sulfate (ZnSO) 4 ) Zinc bis (fluorosulfonyl) imide (Zn (FSI) 2 ) Zinc bis (trifluoromethanesulfonyl) imide (Zn (TFSI) 2 ) Or zinc perchlorate (Zn (ClO) 4 ) 2 ) The fluorine-containing lithium salt includes lithium hexafluorophosphate (LiPF) 6 ) Lithium bis (fluorosulfonyl) imide (LiLSI) or lithium difluoro (oxalato) borate (LiODFB).
Further, the matrix electrolyte comprises polyethylene oxide (PEO), polycarbonate (PC) or Polynitrile (PAN), and the fluorine-containing electrolyte is selected from one fluorine-containing compound of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and 2, 2-Difluoropropionic Acid (DA).
Further, the positive electrode includes lithium cobalt oxide (LiCoO) 2 ) Positive electrode or nickel cobalt lithium manganate (Li) 1+ x Ni y Co z Mn 1-x-y-z O 2 X is more than or equal to 0 and less than or equal to 0.5, y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1), wherein the positive electrode side electrolyte comprises a matrix electrolyte, a lithium salt and a fluorine-containing electrolyte, the negative electrode side electrolyte comprises the matrix electrolyte and the lithium salt, the lithium salt comprises lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide or lithium difluoro (difluoro) oxalato borate, the medium comprises non-Woven Fabric (WFB), a single-layer Polyethylene (PE) diaphragm or a single-layer polypropylene (PP) diaphragm, and the negative electrode material comprises metal lithium sheets or graphite.
One of the technical schemes of the invention is to provide a preparation method of a solid lithium ion battery based on double-layer electrolyte and additive, which comprises the following steps:
(1) Preparing a zinc-containing additive solution, namely dissolving zinc salt and fluorine-containing lithium salt in a first solvent, and stirring until the zinc salt and the fluorine-containing lithium salt are completely dissolved to obtain the zinc-containing additive solution;
(2) Treating a positive electrode material, preparing a positive electrode by adopting a conventional method, uniformly coating a zinc-containing additive solution on the surface of a positive electrode plate, and evaporating a first solvent to obtain a positive electrode plate treated by the zinc-containing additive, namely a zinc positive electrode;
(3) Preparing an anode side electrolyte, namely dissolving a matrix electrolyte, a lithium salt and a fluorine-containing electrolyte in a second solvent, heating to fully swell, dissolve and uniformly mix the matrix electrolyte, the lithium salt and the fluorine-containing electrolyte to obtain the anode side electrolyte;
(4) Preparing a negative electrode side electrolyte, namely dissolving a matrix electrolyte and lithium salt in a second solvent, heating to fully swell, dissolve and uniformly mix the matrix electrolyte and the lithium salt to obtain the negative electrode side electrolyte;
(5) Preparing a double-layer electrolyte and assembling a battery, firstly, pouring an anode side electrolyte on a zinc anode, and covering the anode side electrolyte with a medium to obtain an anode material/anode side electrolyte/medium; then, pouring the negative electrode side electrolyte on the medium surface of the positive electrode side electrolyte/medium to obtain a positive electrode material/positive electrode side electrolyte/medium/negative electrode side electrolyte; then heating the positive electrode material/the positive electrode side electrolyte/the medium/the negative electrode side electrolyte, evaporating the second solvent to obtain a positive electrode material/the bipolar electrode side electrolyte composite material; and finally, placing the anode material on the anode side electrolyte surface of the anode material/bipolar side electrolyte composite material, and assembling to obtain the solid-state lithium ion battery based on the double-layer electrolyte and the additive.
Further, the first solvent in steps (1) and (2) comprises dimethyl carbonate (DMC), dimethyl sulfoxide (DMSO) or Ethyl Acetate (EAC), and the second solvent in steps (3) to (5) comprises acetonitrile, methanol or water.
Further, in the step (1), the concentration of the zinc salt is 0.05-0.3M, the concentration of the fluorine-containing lithium salt is 0.1-0.5M, and the dissolution time is 10-12h.
Further, the coating conditions in step (2) are: the zinc salt in the zinc-containing additive has a mass fraction of 1-7.5wt.%.
As a preferable technical scheme, the evaporating temperature in the step (2) is 55-85 ℃ and the evaporating time is 2-10min.
Further, in the step (3), the mass ratio of the matrix electrolyte, the lithium salt and the fluorine-containing electrolyte is (7.5-10): 1 (6-8), the mass/volume ratio of the sum of the matrix electrolyte, the lithium salt and the fluorine-containing electrolyte to the second solvent is 1g (5-10 mL), and the heating temperature is 55-85 ℃ for 10-24h.
Further, in the step (4), the mass ratio of the matrix electrolyte to the lithium salt is (0.8-1.3): 1, the mass/volume ratio of the sum of the matrix electrolyte and the lithium salt to the second solvent is 1g (5-10 mL), the heating temperature is 55-85 ℃ and the time is 10-24h.
As a preferable technical scheme, the evaporating temperature in the step (5) is 55-65 ℃ and the evaporating time is 12-14h.
The first-week discharge capacity of the solid lithium ion battery is 155-170 mAh.g under the high pressure of 4.5V -1 After 80 weeks of circulation, the capacity retention rate reaches 70-80%, and after multiplying power circulation, the capacity retention rate reaches 95-99% under 0.1-1C multiplying power.
In order to further solve the problems of the prior art based on the patent CN113839092a, a double-layer electrolyte is constructed to protect a transition metal fluoride positive electrode-electrolyte interface (CEI) film formed on the positive electrode, and the core purpose is to prevent transition metal cations from drifting and diffusing into the PEO electrolyte along with charge and discharge, thereby improving the high-voltage stability of the positive electrode-electrolyte interface.
The PVDF-PEO double-layer electrolyte has the advantages that the PVDF surface energy is low, the interaction force with metal fluoride is weak, the energy level of C-F bonds HOMO and LUMO generated by decomposition is low, high pressure resistance is achieved, the PVDF-PEO double-layer electrolyte does not react with metal fluoride, and drift diffusion of metal cations can be effectively inhibited. Wherein, too much fluorine content of the additive is unfavorable for lithium ion conduction of electrolyte, phase resistance of electrolyte is increased, and selected PVDF is only added on the positive electrode side of double-layer electrolyte.
Compared with the prior art, the invention has the following beneficial effects:
(1) The double-layer electrolyte prepared by the invention can protect the stable existence of metal fluoride generated by the additive, solves the problem of drifting diffusion of transition metal cations into an electrolyte body phase, and improves the high-voltage cycling stability of the battery;
(2) The double-layer electrolyte prepared by the method does not react with an anode-electrolyte interface, is well contacted with an electrode, and reduces the polarization degree of the battery;
(3) The zinc-containing additive and the double-layer electrolyte act together to protect the anode; the zinc additive is coated on the surface of the positive electrode plate to prepare a zinc positive electrode, so that the positive electrode structure is protected from collapsing under high voltage, and the stability of a positive electrode-electrolyte interface is improved; the double-layer electrolyte realizes protection of the zinc-containing additive coated on the positive electrode and does not diffuse along with the electrolyte.
Drawings
FIG. 1 is a surface Scanning Electron Microscope (SEM) image of a zinc anode according to example 1 of the present invention;
FIG. 2 is a surface energy spectrum (EDS) of the zinc anode of example 1 of the present invention;
FIG. 3 is an X-ray diffraction (XRD) pattern of a zinc anode, a zinc anode-50 Cs, a lithium cobalt oxide anode, and a lithium cobalt oxide anode-50 Cs in example 1 of the present invention;
FIG. 4 is a cross-sectional SEM image of a polyvinylidene fluoride-polyethylene oxide bilayer electrolyte according to example 1 of the present invention;
fig. 5 is a graph showing cycle performance of solid state lithium ion batteries of example 1 and comparative examples 1 and 2 according to the present invention;
fig. 6 is a cycle charge-discharge graph of a solid state lithium ion battery based on a bi-layer electrolyte and additives in example 1 of the present invention;
fig. 7 is a graph showing the rate performance of solid state lithium ion batteries of example 1 and comparative examples 1 and 2 according to the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
The equipment used in the following examples is representative of conventional equipment in the art unless otherwise specified; unless otherwise indicated, all reagents used are commercially available or prepared by methods conventional in the art, and all of the following examples, not specifically described, are accomplished by means of conventional experimentation in the art.
Example 1:
a solid lithium ion battery based on double-layer electrolyte and additive and a preparation method thereof specifically comprises the following steps:
(1) Preparation of zinc-containing additive solutions in the form of zinc bistrifluoromethane sulphonimide (Zn (TFSI) 2 ) Is 0.075M, lithium hexafluorophosphate (LiPF) 6 ) Is 0.15M, called0.0023g Zn (TFSI) 2 And 0.023g LiPF 6 Dissolving in 300 mu L of dimethyl carbonate (DMC), stirring for 12h until the mixture is completely dissolved, and obtaining zinc-containing additive solution, namely additive-Zn;
(2) Treatment of the cathode Material first, lithium cobalt oxide (LiCoO) was prepared by conventional methods 2 ) The positive electrode, then, zn in Zn (TFSI) as an additive 2 The content was 3.5wt.% of active substance, and 10 μl of additive-Zn was uniformly coated on LiCoO of 10mm diameter 2 Finally evaporating DMC at the evaporating temperature of 60 ℃ for 5min to obtain the additive-Zn treated LiCoO 2 A positive electrode, namely a Zn positive electrode;
specific LiCoO 2 The preparation method of the positive electrode comprises the steps of mixing 1.6g of active material LiCoO with the mass ratio of the active material, the conductive agent and the binder being 8:1:5 2 Uniformly mixing 0.2g of conductive agent acetylene black and 1g of binder polyvinylidene fluoride (PVDF) in 18.48mL of N-methylpyrrolidone (NMP), coating on aluminum foil, and tabletting to obtain LiCoO 2 A positive electrode;
(3) Preparing an electrolyte at the positive electrode side, namely weighing 0.396g of polyethylene oxide (PEO), 0.352g of lithium bistrifluoromethane sulfonyl imide (LiTFSI) and 0.044g of PVDF, dissolving in 6mL of acetonitrile, heating at a heating temperature of 60 ℃ for 12 hours, and fully swelling, dissolving and uniformly mixing the PEO, the LiTFSI and the PVDF to obtain the PVDF-PEO-based electrolyte at the positive electrode side, namely PVDF-PEO for short;
(4) Preparing a negative electrode side electrolyte, namely weighing 0.44g of PEO and 0.36g of LiTFSI in a mass ratio of 11:9, dissolving in 6mL of acetonitrile, and heating for 12 hours at a heating temperature of 60 ℃ to fully swell, dissolve and uniformly mix the PEO and the LiTFSI, so as to obtain the PEO-based negative electrode side electrolyte, namely PEO for short;
(5) Preparing a double-layer electrolyte and assembling a battery, firstly pouring PVDF-PEO obtained in the step (3) on the Zn anode obtained in the step (2), and covering non-Woven Fabrics (WFB), thus obtaining the Zn anode/PVDF-PEO/WFB; then, pouring the PEO obtained in the step (4) on the surface of the WFB of the Zn positive electrode/PVDF-PEO/WFB, so as to obtain the Zn positive electrode/PVDF-PEO/WFB/PEO; heating Zn positive electrode/PVDF-PEO/WFB/PEO, evaporating acetonitrile at the evaporating temperature of 60 ℃ for 12 hours to obtain a positive electrode material/bipolar side electrolyte composite material, wherein the bipolar side electrolyte is called PVDF-PEO/WFB/PEO for short; finally, a metal lithium sheet is used as a negative electrode material and is placed on the PEO surface of a positive electrode material/bipolar side electrolyte composite material to assemble a CR2032 button lithium battery, so that a solid-state lithium ion battery based on PVDF-PEO double-layer electrolyte and Zn-based additive for protecting the positive electrode can be obtained, and the lithium battery obtained in the embodiment 1 is simply called lithium battery-Zn.
To demonstrate the effect of the coating operation, an energy spectrum (EDS) test was performed. The test results are shown in FIG. 1 and FIG. 2, in which Zn elements are uniformly distributed in LiCoO 2 And a positive electrode surface. The test results showed that the coating operation successfully loaded Zn element to LiCoO 2 The surface of the positive electrode.
To demonstrate that the coating additive-Zn-was LiCoO 2 The influence of the positive electrode, performing X-ray diffraction (XRD) test on the Zn positive electrode and performing fine modification; for comparison, at the same time untreated LiCoO 2 The positive electrode was subjected to XRD test. The test results are shown in figure 3,
LiCoO 2 the positive electrode was tested for the presence of LiCoO 2 Characteristic peaks with the same standard peaks;
the Zn positive electrode was tested with LiCoO 2 Is the same as the standard peak of LiCoO 2 The positive electrode has no obvious change;
as can be seen by comparison, the coating additive-Zn-LiCoO 2 The structure of the positive electrode has no influence.
To further demonstrate the additive-Zn versus LiCoO 2 Effect of positive electrode the Zn positive electrode after assembling the battery and cycling for 50 weeks was subjected to XRD test, and the Zn positive electrode after cycling was abbreviated as Zn positive electrode-50 Cs. As shown in FIG. 3, the characteristic peak of Zn positive electrode-50 Cs was found to be similar to LiCoO 2 The standard peaks are similar, but the (003) characteristic peak of the Zn positive electrode shifts to the right. The test results show that due to Li + Is 76pm, zn 2+ The ionic radius of (2) is 75pm, thus, zn during charge and discharge 2+ Occupying Li + Bit leading to Zn positive electrode-50CLiCoO in s 2 The structure of the positive electrode is changed.
To demonstrate the structure of the bilayer electrolyte PVDF-PEO/WFB/PEO, scanning Electron Microscope (SEM) tests were performed. The test results are shown in fig. 4, where there is no obvious boundary between the positive electrode side electrolyte PVDF-PEO and the negative electrode side electrolyte PEO, and the fusion contact is tight.
To demonstrate the effect of PVDF on the interfacial stability of the bilayer electrolyte and Zn positive electrode, comparative example 1, a method of preparing a lithium ion battery without PVDF addition, was provided.
Comparative example 1:
the procedure of example 1 was the same as that of example 1 except that: in the step (3), PVDF is not added, that is, the obtained positive electrode side electrolyte is the same as the negative electrode side electrolyte obtained in the step (4), and the finally obtained double-layer electrolyte is named as PEO-PEO double-layer electrolyte, and the lithium battery obtained in the comparative example 1 is simply named as lithium battery-PEO.
The electrochemical performance test results of lithium battery-PEO are shown in FIG. 5 and Table 1, wherein the solid legend indicates specific capacity, the open legend indicates coulombic efficiency, and the first-week discharge capacity of lithium battery-PEO at 4.5V high pressure is 160.1 mAh.g -1 The capacity retention was 68.5% at 20 weeks of circulation. As a comparison of the test results with example 1 shows, the addition of PVDF can increase the battery cycle life and capacity retention from only 68.5% at 20 weeks to 75.6% at 80 weeks. The reason is that the additive Zn on the surface of the positive electrode is fixed after PVDF is added, so that the additive Zn is prevented from diffusing in the charge and discharge process, and the high-voltage cycle performance of the battery is improved.
The rate charge-discharge test results of lithium battery-PEO are shown in FIG. 7, and the battery is cycled at 0.1C rate, the capacity retention rate is 82%, and the rate is changed to 0.2C capacity and is reduced to 75%; the capacity retention rate was 78% after cycling at different rates and back to 0.1C rate. As can be seen from comparison of the test results with example 1, the addition of PVDF can improve the battery cycle stability, the initial rate capacity retention of 0.1C is increased to 90%, the rate retention is reduced to only 85% after cycling back to 0.1C. The reason is that the PVDF-PEO double-layer electrolyte constructs an interface layer which is more beneficial to lithium ion transmission, so that the PVDF not only inhibits the dispersion of an additive-Zn into an electrolyte phase, but also inhibits the decomposition of the PEO-based electrolyte, and improves the cycling stability of the battery under different multiplying powers.
The following conclusions can be drawn from example 1 and comparative example 1: the interface stability of the electrolyte at the positive electrode side can be improved by adding PVDF, the effect of protecting the Zn positive electrode is realized, and the high-voltage stability of the battery is improved.
To demonstrate the effect of fluorine content in the fluorine-containing electrolyte on the interfacial stability of the bilayer electrolyte and Zn positive electrode, example 2 was provided, a method of preparing a lithium ion battery with Polytetrafluoroethylene (PTFE) in place of PVDF, i.e., a PTFE-PEO bilayer electrolyte.
Example 2:
a lithium ion battery based on PTFE-PEO bilayer electrolyte, the procedure not specifically described was the same as example 1, except that: in the step (3), PVDF is replaced by PTFE, and the lithium battery obtained in the example 2 is simply called lithium battery-PTFE.
The electrochemical performance test results of the lithium battery-PTFE are shown in Table 1, and the initial discharge capacity of the lithium battery-PTFE at 4.5V high pressure is 141.3 mAh.g -1 After 80 weeks of circulation, the capacity retention was 72.3%. As can be seen from comparison of the test results with example 1, when the fluorine content of the fluorine-containing electrolyte is only 2 atoms, the capacity and the retention rate of the battery are improved, and the first-week discharge capacity is improved to 166.2 mAh.g -1 The retention rate is improved to 75.60%. The reason is that PTFE has two fluorine atoms added compared with PVDF, the overall fluorine content is too large, the interaction energy with metal cations becomes strong, and the PTFE is easy to combine with metal elements to take away additives, so that the circulation performance is reduced.
The following conclusions can be drawn from examples 1 and 2: although PTFE and PVDF are similar in structure and function and are fluorine-containing electrolytes, because PTFE has two more fluorine atoms than PVDF, the interaction with metal additives is enhanced, metal elements are easily taken away in the charge and discharge process, the protection function is weakened, and finally the battery cycle performance is attenuated.
To demonstrate the effect of anions on the interfacial stability of the bilayer electrolyte and Zn positive electrode in the fluorous electrolyte, example 3 was provided, a method of making a lithium ion battery with 2, 2-Difluoropropionic Acid (DA) substituted for PVDF, i.e., a DA-PEO bilayer electrolyte based.
Example 3:
a lithium ion battery based on a DA-PEO bilayer electrolyte, the procedure not specifically described was the same as in example 1, except that: in the step (3), PVDF is replaced by DA, and the lithium battery obtained in the example 3 is simply referred to as lithium battery-DA.
The electrochemical performance test results of the lithium battery-DA are shown in Table 1, and the first-week discharge capacity of the lithium battery-DA at a high voltage of 4.5V is 159.3 mAh.g -1 The capacity retention was 50.3% when cycled for 20 weeks. As can be seen from comparison of the test results with example 1, when no anions are present in the fluorine-containing electrolyte, the capacity and retention rate of the battery are improved, and the first-week discharge capacity is improved to 166.2 mAh.g -1 The retention rate is improved to 75.60%. The reason is that anions are easy to react with PEO-based electrolyte to promote the electrolyte to decompose and separate out carbon dioxide (CO) 2 ) Gas, causes deterioration in cycle performance of the battery.
The following conclusions can be drawn from examples 1 and 3: although DA and PVDF are both fluorine-containing electrolytes, since the anions of DA are oxygen-containing acid radicals, DA precipitates during the reaction with the electrolyte, resulting in a drastic decline in the cycle performance.
Therefore, it is demonstrated by examples 2 and 3 that the excessive amount of fluorine in the fluorine-containing electrolyte is easy to carry away the additive, while the presence of the oxygen-containing acid radical in the anion in the fluorine-containing electrolyte reacts with the electrolyte to precipitate gas, i.e., not all fluorine-containing electrolytes can achieve the technical effect of improving the stability of the positive electrode-electrolyte interface.
To demonstrate the protective effect of PVDF on additive treated positive electrodes, comparative example 3 and comparative example 4 were provided, with additive-Cu and additive-Fe treated LiCoO, respectively 2 A positive electrode; for comparison, comparative example 2 was also provided, liCoO without additive treatment 2 And a positive electrode.
Comparative example 2:
a method for producing a lithium ion battery without additive treatment, the procedure not specifically described being the same as in example 1, except that: in the step (1), zn (TFSI) is not added 2 The resulting additive solution was abbreviated as additive-0, and the lithium battery obtained in comparative example 2 was abbreviated as lithium battery-0.
The electrochemical performance test results of the lithium battery-0 are shown in FIG. 5 and Table 1, and the initial cycle discharge capacity of the lithium battery-0 at a high voltage of 4.5V is 149.9 mAh.g -1 The capacity retention was 52.1% at 20 weeks of circulation. As can be seen from comparison of the test results with example 1, after the positive electrode is protected, the first-week discharge capacity of the battery is improved to 166.2 mAh.g -1 The retention rate is improved to 75.60%. The reason is that only PVDF-PEO bilayer electrolyte lacks additive-Zn versus LiCoO 2 In the case of positive electrode protection, liCoO cannot be supported 2 Positive electrode structure, therefore, liCoO under high pressure conditions 2 The structure of the positive electrode collapses, eventually leading to degradation of battery performance.
The rate performance test results of lithium battery-0 are shown in fig. 7, where the capacity retention rate of lithium battery-0 at the initial 0.1C rate is only 70% and after the rate cycle is returned to 0.1C, the capacity retention rate is only 60%. As can be seen from comparison of the test results with example 1, after the positive electrode was protected, the initial rate capacity retention rate of 0.1C was increased to 90%, and after the cycle was returned to 0.1C, the rate retention rate was reduced to only 85%. The multiplying power performance test result is consistent with the electrochemical performance test result.
The following conclusions can be drawn from the comparison of example 1 and comparative example 2: only PVDF-PEO double-layer electrolyte lacks metal elements, and LiCoO cannot be realized 2 Protection of the positive electrode; the conclusion of comparative example 1 is further followed: liCoO can be realized only through the combined action of PVDF-PEO double-layer electrolyte and additive-Zn 2 And the protection effect of the positive electrode.
Comparative example 3:
a method for preparing a lithium ion battery based on additive-Cu, the procedure not specifically described being the same as in example 1, except that: in the step (1), copper bis (trifluoromethanesulfonyl) imide (Cu (TFSI) 2 ) Replacement Zn (TFSI) 2 The resulting additive solution is abbreviated as additive-Cu, and the lithium battery obtained in comparative example 3 is abbreviated as lithium battery-Cu.
The electrochemical performance test results of lithium battery-Cu are shown in Table 1, and the first-week discharge capacity of lithium battery-Cu is 130.1 mAh.g at a high voltage of 4.5V -1 The capacity retention was 68.0% at 20 weeks of circulation. As a result of comparison with example 1, when the additive was Zn 2+ When the first-week discharge capacity of the battery is increased to 166.2 mAh.g -1 The retention rate is improved to 75.60%. The reason is that due to Cu 2+ Has an ionic radius of 73pm and is mixed with Zn 2+ With Li + The difference of the ion radius of (C) is large, so that the (C) cannot be matched with LiCoO in the process of charging and discharging 2 Li-binding coordination in the structure results in failure to achieve protection of LiCoO 2 An effect of the positive electrode; that is, although Zn 2+ And Cu 2+ Are all transition elements adjacent to the fourth period, however, due to Cu 2+ Self-properties and Zn 2+ There is a substantial difference resulting in Cu 2+ Cannot realize protection of LiCoO 2 And the positive electrode, and the stability of the positive electrode-electrolyte interface is improved.
Comparative example 4:
a method for preparing a lithium ion battery based on additive-Fe, the procedure not specifically described being the same as in example 1, except that: in the step (1), bis (trifluoromethanesulfonyl) imide iron (Fe (TFSI) 3 ) Replacement Zn (TFSI) 2 The resulting additive solution is abbreviated as additive-Fe and the lithium battery obtained in comparative example 4 is abbreviated as lithium battery-Fe.
The electrochemical performance test results of lithium battery-Fe are shown in Table 1, and the initial discharge capacity of lithium battery-Fe at 4.5V high pressure is 120.8 mAh.g -1 The capacity retention was 65.6% when cycled for 20 weeks. As a result of comparison with example 1, when the additive was Zn 2+ When the first-week discharge capacity of the battery is increased to 166.2 mAh.g -1 The retention rate is improved to 75.60%. The reason for this is that Fe during charge and discharge 3+ Is reduced to cause valence change, and cannot be combined with LiCoO 2 Li in the structure forms stable coordination, fromBut cannot effectively protect LiCoO 2 A positive electrode; although Fe does not effectively protect LiCoO 2 The principle of the positive electrode is different from Cu, but the realization result shows that Fe is also taken as a transition element of the fourth period 3+ Also cannot effectively protect LiCoO 2 And a positive electrode.
To demonstrate the electrochemical performance of lithium battery-Zn, electrochemical performance tests were performed. The specific test conditions are that the charge-discharge multiplying power is 0.2C in the range of 3-4.5V (vs. Li+/Li) at 60 ℃. The test results are shown in FIG. 5 and Table 1, and the initial cycle discharge capacity of lithium battery-Zn was 166.2 mAh.g at a high pressure of 4.5V -1 After 80 weeks of cycle, the residual discharge capacity was 125.6 mAh.g -1 The capacity retention rate can reach 75.6%. The test result shows that the initial capacity of the lithium battery-Zn battery is high, and the capacity retention rate under high pressure is good.
Table 1 discharge capacity comparison table for electrochemical performance test
In order to demonstrate the high voltage stability of lithium battery-Zn, charge and discharge tests were performed. The specific test conditions are that the charge-discharge multiplying power is 0.2C in the range of 3-4.5V at 60 ℃. The test results are shown in fig. 6, and the discharge capacity of the lithium battery-Zn is slowly attenuated and the charge-discharge curve plateau is gentle when the lithium battery-Zn is cycled for 1 week, 10 weeks, 20 weeks, 30 weeks and 40 weeks at a high pressure of 4.5V, respectively. Test results indicate that the cell has less polarization during cycling.
In order to prove that the multiplying power performance of the lithium battery-Zn is stable, multiplying power charge and discharge tests are carried out. Specific test conditions were that the charge and discharge rates were 0.1C, 0.2C, 0.5C, 1C and 0.1C, respectively, in the range of 3-4.5V (vs. Li+/Li) at 60 ℃. As shown in fig. 7, the lithium battery-Zn was cycled at 4.5V high pressure at different rates with a first week discharge efficiency of 95.7% and a capacity retention of 97.6% when recovered to 0.1C cycle after undergoing four rates. Test results show that the lithium battery-Zn can stably circulate under each multiplying power, and the circulation stability is good under different multiplying powers.
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. The solid lithium ion battery based on the double-layer electrolyte and the additive is characterized by comprising a positive electrode material, a positive electrode side electrolyte, a medium, a negative electrode side electrolyte and a negative electrode material, wherein the positive electrode material is prepared by coating a zinc-containing additive on the surface of a positive electrode plate, the zinc-containing additive comprises zinc salt and fluorine-containing lithium salt, the positive electrode side electrolyte adopts the double-layer electrolyte, and the double-layer electrolyte comprises a matrix electrolyte and fluorine-containing electrolyte.
2. The solid state lithium ion battery based on a bilayer electrolyte and additive according to claim 1 wherein the zinc salt comprises zinc chloride, zinc nitrate, zinc sulfate, zinc bis-fluorosulfonyl imide, zinc bis-trifluoromethane sulfonyl imide or zinc perchlorate and the fluorine-containing lithium salt comprises lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide or lithium difluorooxalato borate.
3. The solid state lithium ion battery of claim 1 wherein the matrix electrolyte comprises polyethylene oxide, polycarbonate or polynitrile and the fluorine containing electrolyte is selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, and 2, 2-difluoropropionic acid.
4. The solid state lithium ion battery of claim 1, wherein the positive electrode comprises a lithium cobalt oxide positive electrode or a lithium nickel cobalt manganese oxide ternary positive electrode, the positive electrode side electrolyte comprises a matrix electrolyte, a lithium salt and a fluorine-containing electrolyte, the negative electrode side electrolyte comprises a matrix electrolyte and a lithium salt, the lithium salt comprises lithium bis (trifluoromethane) sulfonyl imide, lithium bis (fluorine sulfonyl) imide or lithium difluoro (fluorine) oxalato borate, the medium comprises a non-woven fabric, a single layer polyethylene separator or a single layer polypropylene separator, and the negative electrode material comprises a metal lithium sheet or graphite.
5. A method for preparing a solid state lithium ion battery based on a bilayer electrolyte and an additive according to any one of claims 1 to 4, characterized in that the method comprises the steps of:
(1) Preparing a zinc-containing additive solution, namely dissolving zinc salt and fluorine-containing lithium salt in a first solvent to obtain the zinc-containing additive solution;
(2) The method comprises the steps of treating a positive electrode material, uniformly coating a zinc-containing additive solution on the surface of a positive electrode plate, and evaporating a first solvent to obtain a positive electrode plate treated by the zinc-containing additive, namely a zinc positive electrode;
(3) Preparing an anode side electrolyte, namely dissolving a matrix electrolyte, lithium salt and a fluorine-containing electrolyte in a second solvent, and heating to obtain the anode side electrolyte;
(4) Preparing a negative electrode side electrolyte, namely dissolving a matrix electrolyte and lithium salt in a second solvent, and heating to obtain the negative electrode side electrolyte;
(5) Preparing a double-layer electrolyte and assembling a battery, firstly, pouring an anode side electrolyte on a zinc anode, and covering the anode side electrolyte with a medium to obtain an anode material/anode side electrolyte/medium; then, pouring the negative electrode side electrolyte on the medium surface of the positive electrode side electrolyte/medium to obtain a positive electrode material/positive electrode side electrolyte/medium/negative electrode side electrolyte; then, heating the positive electrode material/the positive electrode side electrolyte/the medium/the negative electrode side electrolyte, and evaporating the second solvent to obtain a positive electrode material/the bipolar electrode side electrolyte composite material; and finally, placing the anode material on the anode side electrolyte surface of the anode material/bipolar side electrolyte composite material, and assembling to obtain the solid-state lithium ion battery based on the double-layer electrolyte and the additive.
6. The method of claim 5, wherein the first solvent in steps (1) and (2) comprises dimethyl carbonate, dimethyl sulfoxide or ethyl acetate, and the second solvent in steps (3) to (5) comprises acetonitrile, methanol or water.
7. The method for preparing a solid lithium ion battery based on a bilayer electrolyte and an additive according to claim 5, wherein the concentration of the zinc salt in the step (1) is 0.05-0.3M, the concentration of the fluorine-containing lithium salt is 0.1-0.5M, and the dissolution time is 10-12h.
8. The method for preparing a solid lithium ion battery based on a bilayer electrolyte and an additive according to claim 5, wherein the coating conditions in step (2) are: the zinc salt in the zinc-containing additive has a mass fraction of 1-7.5wt.%.
9. The method for preparing a solid lithium ion battery based on a double-layer electrolyte and an additive according to claim 5, wherein in the step (3), the mass ratio of the matrix electrolyte, the lithium salt and the fluorine-containing electrolyte is (7.5-10): (6-8): 1, the mass/volume ratio of the sum of the matrix electrolyte, the lithium salt and the fluorine-containing electrolyte and the second solvent is 1g (5-10 mL), and the heating temperature is 55-85 ℃ for 10-24 hours.
10. The method for preparing a solid lithium ion battery based on a double-layer electrolyte and an additive according to claim 5, wherein the mass ratio of the matrix electrolyte to the lithium salt in the step (4) is (0.8-1.3): 1, the mass/volume ratio of the sum of the matrix electrolyte and the lithium salt to the second solvent is 1g (5-10 mL), the heating temperature is 55-85 ℃ and the time is 10-24h.
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