CN117790895A - High-entropy suspension ether electrolyte and lithium ion battery thereof - Google Patents
High-entropy suspension ether electrolyte and lithium ion battery thereof Download PDFInfo
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- CN117790895A CN117790895A CN202410133971.7A CN202410133971A CN117790895A CN 117790895 A CN117790895 A CN 117790895A CN 202410133971 A CN202410133971 A CN 202410133971A CN 117790895 A CN117790895 A CN 117790895A
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- lithium
- ether
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- ether electrolyte
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- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 title claims abstract description 210
- 239000003792 electrolyte Substances 0.000 title claims abstract description 109
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 101
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 101
- 239000000725 suspension Substances 0.000 title claims abstract description 49
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims abstract description 64
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims abstract description 57
- 239000000654 additive Substances 0.000 claims abstract description 35
- 230000000996 additive effect Effects 0.000 claims abstract description 29
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims abstract description 20
- 229910052808 lithium carbonate Inorganic materials 0.000 claims abstract description 20
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910001947 lithium oxide Inorganic materials 0.000 claims abstract description 20
- 239000006259 organic additive Substances 0.000 claims abstract description 19
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 239000002994 raw material Substances 0.000 claims abstract description 5
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 77
- 239000002904 solvent Substances 0.000 claims description 24
- 229910052744 lithium Inorganic materials 0.000 claims description 21
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 19
- 239000011230 binding agent Substances 0.000 claims description 18
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 16
- 239000012528 membrane Substances 0.000 claims description 15
- 239000006258 conductive agent Substances 0.000 claims description 12
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 11
- ZUHZGEOKBKGPSW-UHFFFAOYSA-N tetraglyme Chemical compound COCCOCCOCCOCCOC ZUHZGEOKBKGPSW-UHFFFAOYSA-N 0.000 claims description 10
- 229910052736 halogen Inorganic materials 0.000 claims description 9
- 150000002367 halogens Chemical class 0.000 claims description 9
- 229910003002 lithium salt Inorganic materials 0.000 claims description 9
- 159000000002 lithium salts Chemical class 0.000 claims description 9
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 claims description 8
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 6
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims description 5
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 5
- 239000007773 negative electrode material Substances 0.000 claims description 5
- 239000007774 positive electrode material Substances 0.000 claims description 4
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims description 4
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 2
- 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 claims 1
- RFGOKUXULFJHDS-UHFFFAOYSA-N FN=S(F)F.FN=S(F)F.[Li] Chemical compound FN=S(F)F.FN=S(F)F.[Li] RFGOKUXULFJHDS-UHFFFAOYSA-N 0.000 claims 1
- 230000004913 activation Effects 0.000 abstract description 13
- 238000009792 diffusion process Methods 0.000 abstract description 12
- 238000010351 charge transfer process Methods 0.000 abstract description 4
- 230000002195 synergetic effect Effects 0.000 abstract description 3
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 52
- 229910013553 LiNO Inorganic materials 0.000 description 29
- 230000000052 comparative effect Effects 0.000 description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 22
- 238000012360 testing method Methods 0.000 description 21
- XKTYXVDYIKIYJP-UHFFFAOYSA-N 3h-dioxole Chemical compound C1OOC=C1 XKTYXVDYIKIYJP-UHFFFAOYSA-N 0.000 description 16
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 16
- 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 16
- 229910002804 graphite Inorganic materials 0.000 description 14
- 239000010439 graphite Substances 0.000 description 14
- 238000002156 mixing Methods 0.000 description 14
- 239000002033 PVDF binder Substances 0.000 description 12
- 239000011248 coating agent Substances 0.000 description 12
- 238000000576 coating method Methods 0.000 description 12
- 239000007888 film coating Substances 0.000 description 12
- 238000009501 film coating Methods 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 12
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 12
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 10
- 238000009830 intercalation Methods 0.000 description 9
- 229910018068 Li 2 O Inorganic materials 0.000 description 8
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 7
- 239000006230 acetylene black Substances 0.000 description 6
- 239000006256 anode slurry Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 239000011267 electrode slurry Substances 0.000 description 6
- 229910021382 natural graphite Inorganic materials 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 238000007614 solvation Methods 0.000 description 6
- 238000001291 vacuum drying Methods 0.000 description 6
- HNJBEVLQSNELDL-UHFFFAOYSA-N pyrrolidin-2-one Chemical compound O=C1CCCN1 HNJBEVLQSNELDL-UHFFFAOYSA-N 0.000 description 5
- 238000005481 NMR spectroscopy Methods 0.000 description 4
- 238000001237 Raman spectrum Methods 0.000 description 4
- 238000004807 desolvation Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 150000001450 anions Chemical class 0.000 description 3
- 229910021383 artificial graphite Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 239000003365 glass fiber Substances 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000002153 silicon-carbon composite material Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- OHVLMTFVQDZYHP-UHFFFAOYSA-N 1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-2-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound N1N=NC=2CN(CCC=21)C(CN1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)=O OHVLMTFVQDZYHP-UHFFFAOYSA-N 0.000 description 2
- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 2
- DFGKGUXTPFWHIX-UHFFFAOYSA-N 6-[2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]acetyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)CC(=O)C1=CC2=C(NC(O2)=O)C=C1 DFGKGUXTPFWHIX-UHFFFAOYSA-N 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 2
- 239000004210 ether based solvent Substances 0.000 description 2
- 229910021385 hard carbon Inorganic materials 0.000 description 2
- 238000002329 infrared spectrum Methods 0.000 description 2
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910021384 soft carbon Inorganic materials 0.000 description 2
- NAMDIHYPBYVYAP-UHFFFAOYSA-N 1-methoxy-2-(2-methoxyethoxy)ethane Chemical compound COCCOCCOC.COCCOCCOC NAMDIHYPBYVYAP-UHFFFAOYSA-N 0.000 description 1
- VZSRBBMJRBPUNF-UHFFFAOYSA-N 2-(2,3-dihydro-1H-inden-2-ylamino)-N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]pyrimidine-5-carboxamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C(=O)NCCC(N1CC2=C(CC1)NN=N2)=O VZSRBBMJRBPUNF-UHFFFAOYSA-N 0.000 description 1
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 238000001069 Raman spectroscopy Methods 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
- 230000006978 adaptation Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010504 bond cleavage reaction Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000739 chaotic effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002484 cyclic voltammetry Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 238000001453 impedance spectrum Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000002931 mesocarbon microbead Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Secondary Cells (AREA)
Abstract
The invention provides a high-entropy suspension ether electrolyte and a lithium ion battery thereof, and belongs to the technical field of lithium ion batteries. The high-entropy suspension ether electrolyte comprises the following raw materials: a base ether electrolyte, an organic additive and an inorganic additive; wherein the inorganic additive is a mixture of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and lithium nitrate. According to the invention, the inorganic additive and the organic additive are added into the basic ether electrolyte, and the stable SEI film can be formed by the synergistic effect of the organic additive and the inorganic additive, so that the activation energy in the diffusion process and the charge transfer process of the electrolyte is reduced, the diffusion resistance of lithium ions is obviously reduced, the diffusion kinetics of the lithium ions is accelerated, and the electrochemical performance and the low-temperature performance of the lithium ion battery are improved.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a high-entropy suspension ether electrolyte and a lithium ion battery thereof.
Background
Lithium ion batteries are the most successful commercial secondary batteries today, which have the advantages of high practical energy density, long cycle life, etc. However, the Electric Vehicle (EV) industry, which is actively developed, puts more stringent demands on battery performance, such as fast charge capability and safety over a wide temperature range. In particular, the negative electrode is considered to be battery safe and fast charging due to its slow electrochemical reaction kineticsPerformance limitations. In practical application, the graphite cathode has higher theoretical specific capacity (372 mAh.g -1 ) Good electron and ion conductivity and longer cycle life, coupled with their lower lithium intercalation potential (< 0.2Vvs Li) + Li) to enable the battery to achieve a relatively high energy density and thus to be a common negative electrode material for commercial Lithium Ion Batteries (LIB). However, the problem of co-intercalation of an ether solvent in a basic ether electrolyte exists in the graphite cathode, so that the graphite is peeled off and stripped in the circulation process, and the performance is poor. In addition, when the lithium ion battery is charged at a low temperature, lithium ions cannot be intercalated into graphite, deposition and lithium precipitation occur on the surface of the lithium ion battery, and therefore potential safety hazards are generated. It can be seen that the problem of interfacial stability between the graphite negative electrode and the electrolyte is a problem that hinders the improvement of electrolyte performance, and even the forward development of lithium ion battery technology.
Therefore, research on the high-entropy suspension ether electrolyte is significant in solving the co-intercalation problem of the graphite cathode and the ether solvent and improving the electrochemical performance of the lithium ion battery when the high-entropy suspension ether electrolyte is used in the lithium ion battery.
Disclosure of Invention
The invention aims to provide a high-entropy suspension ether electrolyte and a lithium ion battery thereof, which are used for solving the problems of co-intercalation of an ether solvent and poor electrochemical performance of the lithium ion battery in a basic ether electrolyte of a graphite cathode.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a high-entropy suspension ether electrolyte, which comprises the following raw materials: a base ether electrolyte, an organic additive and an inorganic additive; the inorganic additive is a mixture of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and nano lithium nitrate.
Preferably, the basic ether electrolyte consists of an ether solvent, a halogen-containing lithium salt and lithium nitrate.
Preferably, the ether solvent comprises one or more of ethylene glycol dimethyl ether, 1, 3-dioxolane, tetraethylene glycol dimethyl ether, 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether.
Preferably, the halogen-containing lithium salt contains one or more of lithium hexafluorophosphate, lithium bistrifluoro-methylsulfonyl imide, lithium bistrifluoro-sulfonyl imide, lithium perchlorate, lithium difluorooxalato borate and lithium tetrafluoroborate.
Preferably, the concentration of lithium ions in the basic ether electrolyte is 0.5-2 mol/L; in the basic ether electrolyte, the mass of lithium nitrate is 1-3% of the total mass of the basic ether electrolyte.
Preferably, the organic additive comprises fluoroethylene carbonate and/or vinylene carbonate.
Preferably, the volume of the organic additive accounts for 3-7% of the total volume of the high-entropy suspension ether electrolyte.
Preferably, in the high-entropy suspension ether electrolyte, the concentration of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and nano lithium nitrate is independently 0.05-0.5 mol/L.
The invention also provides a lithium ion battery, which comprises an anode, a cathode, a separation film and the high-entropy suspension ether electrolyte.
Preferably, the positive electrode comprises a positive electrode current collector and a positive electrode membrane, and the negative electrode comprises a negative electrode current collector and a negative electrode membrane; the positive electrode membrane comprises a positive electrode active material, a conductive agent and a binder; the negative electrode membrane includes a negative electrode active material, a conductive agent, and a binder.
The invention has the beneficial effects that:
(1) According to the invention, the inorganic additive and the organic additive are added into the basic ether electrolyte, and the stable SEI film can be formed by the synergistic effect of the organic additive and the inorganic additive, so that the activation energy in the diffusion process and the charge transfer process of the electrolyte is reduced, the diffusion resistance of lithium ions is obviously reduced, and the diffusion kinetics of lithium ions is accelerated.
(2) The high-entropy suspension ether electrolyte can obviously reduce the solvent co-intercalation phenomenon of the graphite cathode in the electrolyte, and improves the rate capability and low-temperature capability of the lithium ion battery.
Drawings
FIG. 1 is an external appearance of the high entropy suspension ether electrolyte (1.4M LDD-4S+5% FEC) of example 1;
FIG. 2 1.4M LDD-LiF+5% FEC of comparative example 2, 1.4MLDD-Li of comparative example 3 2 O+5% FEC, 1.4M LDD-Li of comparative example 4 2 CO 3 +5% FEC and 1.4M LDD-LiNO of comparative example 5 3 Appearance state of +5% fec;
FIG. 3 is a Raman spectrum, an infrared spectrum and a Raman spectrum of the LDD of comparative example 1, the 1.4M LDD+5% FEC of comparative example 6 and the 1.4M LDD-4S+5% FEC of example 1 7 Li Nuclear magnetic resonance image, wherein a is the Raman spectrum of LDD,1.4M LDD+5% FEC and 1.4M LDD-4S+5% FEC, b is the IR spectrum of LDD,1.4M LDD+5% FEC and 1.4M LDD-4S+5% FEC, c is the Raman spectrum of LDD and 1.4M LDD-4S+5% FEC 7 Li nuclear magnetic resonance diagram;
FIG. 4 is a graph showing the comparison of the ionic conductivities of LDD of comparative example 1 and 1.4M LDD-4S+5% FEC of example 1, R ct Activation energy and R sei An activation energy contrast diagram, wherein a is an ion conductivity contrast diagram, and b is R ct The activation energy contrast diagram, c is R sei An activation energy comparison chart;
FIG. 5 is a charge-discharge graph of lithium ion battery DII-1;
FIG. 6 is a CV plot and a dQ/dV differential capacity plot of lithium ion batteries DII-1 and II-1, wherein a is the CV plot of lithium ion battery DII-1, b is the CV plot of lithium ion battery II-1, c is the dQ/dV differential capacity plot of lithium ion battery DII-1, and d is the dQ/dV differential capacity plot of lithium ion battery II-1;
FIG. 7 is an EIS diagram of lithium ion batteries DII-1 and II-1;
FIG. 8 is a charge-discharge graph of the lithium ion battery II-1 and a ratio performance graph and a cycle performance graph of the lithium ion batteries DII-1 and II-1, wherein a is a charge-discharge graph of the lithium ion battery II-1, b is a ratio performance graph of the lithium ion batteries DII-1 and II-1, and c is a cycle performance graph of the lithium ion batteries DII-1 and II-1;
FIG. 9 is a graph of the charge and discharge of lithium ion batteries DII-7, DII-8, DII-9, and DII-10 at a current density of 0.1C, wherein a is the graph of DII-7, b is the graph of DII-8, C is the graph of DII-9, and d is the graph of DII-10;
FIG. 10 is a graph of cycle performance and coulombic efficiency for lithium ion batteries II-1, DII-7, DII-8, DII-9, and DII-10, where a is the cycle performance graph and b is the coulombic efficiency graph;
FIG. 11 is a graph of the charge and discharge curves of the lithium ion battery DII-6 and the rate performance curves of the lithium ion batteries DII-6 and II-1, wherein a is the charge and discharge curve of the lithium ion battery DII-6 and b is the rate performance curves of the lithium ion batteries DII-6 and II-1;
FIG. 12 is a graph of rate performance for lithium ion batteries DII-2, DII-3, DII-4, DII-5;
FIG. 13 is a graph showing low temperature performance of DII-1 and II-1, wherein a is electrochemical performance of DII-1 and II-1 at different temperatures, b is charge and discharge curve of DII-1 at different temperatures, and c is charge and discharge curve of II-1 at different temperatures.
Detailed Description
The invention provides a high-entropy suspension ether electrolyte, which comprises the following raw materials: a base ether electrolyte, an organic additive and an inorganic additive; the inorganic additive is a mixture of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and nano lithium nitrate.
In the invention, the basic ether electrolyte consists of an ether solvent, a halogen-containing lithium salt and lithium nitrate.
In the present invention, the ether solvent comprises one or more of ethylene glycol dimethyl ether (DME), 1, 3-Dioxolane (DOL), tetraethylene glycol dimethyl ether (TEGDME), 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether (HFE), diethylene glycol dimethyl ether (DIGLYME) and triethylene glycol dimethyl ether (TEDM), preferably, it is one or more of ethylene glycol dimethyl ether, 1, 3-dioxolane, tetraethylene glycol dimethyl ether and 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether, and more preferably, ethylene glycol dimethyl ether and 1, 3-dioxolane. When the above two or more types of ether solvents are used, the ratio of the different types of ether solvents is not particularly limited.
In the present invention, the halogen-containing lithium salt comprises hexafluoroLithium phosphate (LiPF) 6 ) Lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiSSI), lithium perchlorate (LiClO) 4 ) Lithium difluorooxalato borate (LiDFOB) and lithium tetrafluoroborate (LiBF) 4 ) Preferably one or more of lithium hexafluorophosphate, lithium bistrifluoro-methylsulfonyl-imide, lithium bistrifluoro-sulfonyl-imide and lithium perchlorate, and more preferably lithium hexafluorophosphate and/or lithium bistrifluoro-methylsulfonyl-imide.
In the present invention, the concentration of lithium ions in the base ether electrolyte is 0.5 to 2mol/L, preferably 0.8 to 1.5mol/L, and more preferably 1 to 1.2mol/L; in the basic ether electrolyte, the mass of lithium nitrate is 1 to 3 percent, preferably 2 percent of the total mass of the basic ether electrolyte.
In the present invention, the organic additive comprises fluoroethylene carbonate (FEC) and/or Vinylene Carbonate (VC), preferably fluoroethylene carbonate. The addition of fluoroethylene carbonate (FEC) and/or Vinylene Carbonate (VC) is beneficial to forming an inorganic film, and can also increase organic components in the SEI film, so that the formed organic-inorganic composite SEI film has high toughness and better ionic conductivity.
In the present invention, the volume of the organic additive is 3 to 7%, preferably 4 to 6%, and more preferably 5% of the total volume of the high-entropy suspension ether electrolyte.
In the high-entropy suspension ether electrolyte, the concentration of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and nano lithium nitrate is independently 0.05 to 0.5mol/L, preferably 0.1 to 0.4mol/L.
In the invention, the addition of the inorganic additives of nano lithium oxide, lithium fluoride, nano lithium carbonate and lithium nitrate can form a high entropy system Li + The solvation structure improves the dynamics of lithium ions due to weaker solvation caused by higher disorder of the system, and the solvation structure rich in anions promotes the electrode surface to form a stable interface at low temperature, thereby being beneficial to improving the low-temperature performance of the lithium ion battery.
The invention also provides a lithium ion battery, which comprises an anode, a cathode, a separation film and the high-entropy suspension ether electrolyte.
In the invention, the positive electrode comprises a positive electrode current collector and a positive electrode membrane, and the negative electrode comprises a negative electrode current collector and a negative electrode membrane; the positive electrode membrane comprises a positive electrode active material, a conductive agent and a binder; the negative electrode membrane includes a negative electrode active material, a conductive agent, and a binder.
In the present invention, the positive electrode active material contains one or more of lithium cobaltate, lithium nickel cobalt manganate, lithium iron phosphate and lithium manganate, preferably one or more of lithium cobaltate, lithium iron phosphate and lithium manganate, further preferably lithium cobaltate and/or lithium iron phosphate.
In the present invention, the negative electrode active material contains one or more of metallic lithium, natural graphite, artificial graphite, mesophase micro carbon spheres (abbreviated as MCMB), hard carbon, soft carbon, silicon and silicon-carbon composite, preferably one or more of natural graphite, artificial graphite, hard carbon, soft carbon, silicon and silicon-carbon composite, and more preferably one or more of natural graphite, artificial graphite and silicon-carbon composite.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
The basic ether electrolyte used in examples 1 to 3 and comparative examples 1 to 10 of the present invention was commercial ether electrolyte, purchased from Kolu, and model MA-EN-EL-0O0516.
Example 1
The composition of the basic ether electrolyte is as follows: the volume ratio of the ethylene glycol dimethyl ether (DME) to the 1, 3-Dioxolane (DOL) is 1:1, the halogen-containing lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI), wherein the concentration of lithium ions is 1mol/L, the mass concentration of lithium nitrate is 2%, and the lithium nitrate is recorded as 1MLiTFSI-DOL/DME+2% LiNO 3 Abbreviated as LDD.
Adding nano lithium oxide, lithium fluoride, nano lithium carbonate and lithium nitrate into the basic ether electrolyte in sequence to ensure that the concentration of the nano lithium oxide, the concentration of the lithium fluoride, the concentration of the nano lithium carbonate and the concentration of the nano lithium nitrate are all 0.1mol/L, and adding after uniformly mixingAdding fluoroethylene carbonate (FEC) (the volume of fluoroethylene carbonate accounts for 5% of the total volume of the high-entropy suspension ether electrolyte), stirring for 24h to obtain the high-entropy suspension ether electrolyte, which is recorded as 1M LiTFSI-DOL/DME+2% LiNO 3 +0.1M LiF+0.1M Li 2 O+0.1MLi 2 CO 3 +0.1M LiNO 3 +5% FEC, abbreviated as 1.4M LDD-4S+5% FEC.
Preparation of a positive electrode plate: mixing lithium iron phosphate, binder polyvinylidene fluoride and conductive agent acetylene black according to a mass ratio of 8:1:1, and then adding N-methyl pyrrolidone solvent (the mass volume ratio of the binder polyvinylidene fluoride to the N-methyl pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the anode slurry. And (3) coating the anode slurry on the aluminum foil by adopting a film coating instrument, wherein the thickness of the coating is 100 mu m, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the anode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, the dried electrode is cut into positive electrode plates with the diameter of 12mm by a wafer slicer.
Preparation of a negative electrode plate: mixing natural graphite, binder polyvinylidene fluoride and conductive agent acetylene black according to the mass ratio of 90:5:5, and then adding N-methyl pyrrolidone (NMP) (the mass-volume ratio of the binder polyvinylidene fluoride to the pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the negative electrode slurry. And (3) coating the negative electrode slurry on the copper foil by adopting a film coating instrument, wherein the thickness of the coating is 100 mu m, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the negative electrode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, a wafer slicer is used for cutting the cathode electrode plate with the diameter of 12 mm.
And assembling the positive electrode plate, the negative electrode plate, the glass fiber membrane (GF/A) and the high-entropy suspension ether electrolyte into a lithium ion battery (recorded as II-1) in a glove box, wherein the addition amount of the high-entropy suspension ether electrolyte is 90 mu L, and standing the lithium ion battery for 10 hours for electrochemical testing.
Example 1 selection of commercial 1M LiTFSI-DOL/DME+2% LiNO 3 (called LDD for short) as basic ether electrolyte, liF and Li are added into the basic ether electrolyte 2 O、Li 2 CO 3 、LiNO 3 And FEC, wherein LiF, li 2 O、Li 2 CO 3 、LiNO 3 The concentration of (2) was 0.1M and the volume content of FEC was 5%, and a high entropy suspension ether electrolyte was obtained as a highly chaotic suspension (as shown in FIG. 1).
Example 2
The composition of the basic ether electrolyte is as follows: the volume ratio of the ethylene glycol dimethyl ether (DME) to the 1, 3-Dioxolane (DOL) is 1:1, the halogen-containing lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI), wherein the concentration of lithium ions is 1mol/L, the mass concentration of lithium nitrate is 2%, and the lithium nitrate is recorded as 1MLiTFSI-DOL/DME+2% LiNO 3 Abbreviated as LDD.
Sequentially adding nano lithium oxide, lithium fluoride, nano lithium carbonate and lithium nitrate into the basic ether electrolyte to ensure that the concentration of the nano lithium oxide, the concentration of the nano lithium fluoride, the concentration of the nano lithium carbonate and the concentration of the nano lithium nitrate are all 0.2mol/L, adding fluoroethylene carbonate (FEC) (the volume of the fluoroethylene carbonate is 3 percent of the total volume of the high-entropy suspension ether electrolyte), stirring for 24 hours, and uniformly mixing to obtain the high-entropy suspension ether electrolyte, which is recorded as 1M LiTFSI-DOL/DME+2% LiNO 3 +0.2M LiF+0.2M Li 2 O+0.2MLi 2 CO 3 +0.2M LiNO 3 +3% FEC, abbreviated as 1.8M LDD-4S+3% FEC.
Preparation of a positive electrode plate: mixing lithium iron phosphate, binder polyvinylidene fluoride and conductive agent acetylene black according to a mass ratio of 8:1:1, and then adding N-methyl pyrrolidone solvent (the mass volume ratio of the binder polyvinylidene fluoride to pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the anode slurry. And (3) coating the anode slurry on the aluminum foil by adopting a film coating instrument, wherein the thickness of the coating is 100 mu m, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the anode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, a wafer slicer is used for cutting the anode electrode plate with the diameter of 12 mm.
Preparation of a negative electrode plate: mixing natural graphite, binder polyvinylidene fluoride and conductive agent acetylene black according to the mass ratio of 90:5:5, and then adding N-methyl pyrrolidone (NMP) (the mass-volume ratio of the binder polyvinylidene fluoride to the pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the negative electrode slurry. And (3) coating the negative electrode slurry on the copper foil by adopting a film coating instrument, wherein the thickness of the coating is 100 mu m, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the negative electrode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, a wafer slicer is used for cutting the cathode electrode plate with the diameter of 12 mm.
The positive electrode plate, the negative electrode plate, the glass fiber membrane (GF/A) and the high-entropy suspension ether electrolyte are assembled into a lithium ion battery (recorded as II-2) in a glove box, and the addition amount of the high-entropy suspension ether electrolyte is 90 mu L.
Example 3
The composition of the basic ether electrolyte is as follows: the volume ratio of the ethylene glycol dimethyl ether (DME) to the 1, 3-Dioxolane (DOL) is 1:1, the halogen-containing lithium salt is lithium bis (trifluoromethanesulfonyl imide) (LiTFSI), wherein the concentration of lithium ions is 1mol/L, the mass concentration of lithium nitrate is 2%, and the lithium nitrate is recorded as 1MLiTFSI-DOL/DME+2% LiNO 3 Abbreviated as LDD.
Sequentially adding nano lithium oxide, lithium fluoride, nano lithium carbonate and lithium nitrate into the basic ether electrolyte to ensure that the concentration of the nano lithium oxide, the concentration of the nano lithium fluoride, the concentration of the nano lithium carbonate and the concentration of the nano lithium nitrate are all 0.5mol/L, adding fluoroethylene carbonate (FEC) (the volume of the fluoroethylene carbonate is 7 percent of the total volume of the high-entropy suspension ether electrolyte), stirring for 24 hours, and uniformly mixing to obtain the high-entropy suspension ether electrolyte, which is recorded as 1M LiTFSI-DOL/DME+2% LiNO 3 +0.5M LiF+0.5M Li 2 O+0.5MLi 2 CO 3 +0.5M LiNO 3 +7% FEC, abbreviated as 3M LDD-4S+7% FEC.
Preparation of a positive electrode plate: mixing lithium iron phosphate, binder polyvinylidene fluoride and conductive agent acetylene black according to a mass ratio of 8:1:1, and then adding N-methyl pyrrolidone solvent (the mass volume ratio of the binder polyvinylidene fluoride to pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the anode slurry. And (3) coating the anode slurry on the aluminum foil by adopting a film coating instrument, wherein the thickness of the coating is 100 micrometers, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the anode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, the dried electrode is cut into positive electrode plates with the diameter of 12mm by a wafer slicer.
Preparation of a negative electrode plate: mixing natural graphite, binder polyvinylidene fluoride and conductive agent acetylene black according to the mass ratio of 90:5:5, and then adding N-methyl pyrrolidone (NMP) (the mass-volume ratio of the binder polyvinylidene fluoride to the pyrrolidone is 40mg:1 mL) for uniform mixing to obtain the negative electrode slurry. And (3) coating the negative electrode slurry on the copper foil by adopting a film coating instrument, wherein the thickness of the coating is 100 mu m, and heating a heating flat plate of the film coating instrument to 80 ℃ to primarily dry the negative electrode. The preliminarily dried electrode was placed in a vacuum drying oven and dried at 120℃for 10 hours. Finally, the dried electrode is cut into a negative electrode plate with the diameter of 12mm by a wafer slicer.
The positive electrode plate, the negative electrode plate, the glass fiber membrane (GF/A) and the high-entropy suspension ether electrolyte are assembled into a lithium ion battery (recorded as II-3) in a glove box, and the addition amount of the high-entropy suspension ether electrolyte is 90 mu L.
Comparative example 1
The difference from example 1 is that the electrolyte used in assembling the lithium ion battery is a basic ether electrolyte (abbreviated as LDD), and the other conditions are the same, and the assembled lithium ion battery is denoted as DII-1.
Comparative example 2
The difference from example 1 is that only one inorganic additive of lithium fluoride was added, the concentration of lithium fluoride was 0.4mol/L, and the other conditions were the same, to obtain a mixed ether electrolyte, which was designated as 1MLiTFSI+DOL/DME+2% LiNO 3 +0.4M LiF+5% FEC, abbreviated as 1.4MLDD-LiF+5% FEC, the assembled lithium ion battery was designated DII-2.
Comparative example 3
The difference with example 1 is that only one inorganic additive of nano lithium oxide is added, the concentration of nano lithium oxide is 0.4mol/L, and other conditions are the same, so as to obtain high-entropy suspension ether electrolyte which is marked as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M Li 2 O+5% FEC, abbreviated as 1.4MLDD-Li 2 O+5% FEC, the assembled lithium ion battery was designated DII-3.
Comparative example 4
The difference from example 1 is that only nano lithium carbonate is addedThe inorganic additive is added, the concentration of nano lithium carbonate is 0.4mol/L, and other conditions are the same, so that the high-entropy suspension ether electrolyte is obtained and is marked as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M Li 2 CO 3 +5% FEC, abbreviated as 1.4MLDD-Li 2 CO 3 +5% FEC, the assembled lithium ion battery was designated DII-4.
Comparative example 5
The difference from example 1 is that only one inorganic additive of lithium nitrate is added, the concentration of lithium nitrate is 0.4mol/L, and the other conditions are the same, so as to obtain a mixed ether electrolyte, which is marked as 1MLiTFSI+DOL/DME+2% LiNO 3 +0.4M LiNO 3 +5% FEC, abbreviated as 1.4MLDD-LiNO 3 +5% FEC, the assembled lithium ion battery was designated DII-5.
Comparative example 6
The difference from example 1 is that no inorganic additive was added and LiTFSI was added to prepare a mixed ether electrolyte so that the concentration of LiTFSI in the mixed ether electrolyte was 1.4mol/L, and the other conditions were the same, denoted as 1.4M LiTFSI+DOL/DME+2% LiNO 3 +5% FEC, abbreviated as 1.4MLDD+5% FEC, the assembled lithium ion battery was designated DII-6.
Comparative example 7
The difference from example 1 is that only one inorganic additive of lithium fluoride was added, the concentration of lithium fluoride was 0.4mol/L, fluoroethylene carbonate was not added, and the other conditions were the same, to obtain a mixed ether electrolyte, which was designated as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M LiF, abbreviated as 1.4MLDD-LiF, the assembled lithium ion battery was designated DII-7.
Comparative example 8
The difference from example 1 is that only one inorganic additive of nano lithium oxide was added, the concentration of nano lithium oxide was 0.4mol/L, fluoroethylene carbonate was not added, and the other conditions were the same, a mixed ether electrolyte was obtained, which was designated as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M Li 2 O, abbreviated as 1.4M LDD-Li 2 O, the assembled lithium ion battery was designated DII-8.
Comparative example 9
The difference from example 1 is thatThus, only one inorganic additive of nano lithium carbonate is added, the concentration of nano lithium carbonate is 0.4mol/L, fluoroethylene carbonate is not added, and other conditions are the same, so that a mixed ether electrolyte is obtained and is marked as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M Li 2 CO 3 Abbreviated as 1.4M LDD-Li 2 CO 3 The assembled lithium ion battery is designated as DII-9.
Comparative example 10
The difference from example 1 is that only one inorganic additive of lithium nitrate was added, the concentration of lithium nitrate was 0.4mol/L, fluoroethylene carbonate was not added, and the other conditions were the same, to obtain a mixed ether electrolyte, which was designated as 1M LiTFSI+DOL/DME+2% LiNO 3 +0.4M LiNO 3 Is abbreviated as 1.4MLDD-LiNO 3 The assembled lithium ion battery is designated as DII-10.
FIG. 2 is an external appearance of electrolytes of comparative examples 2 to 5, in which 1.4MLDD-LiF+5% FEC of comparative example 2 and 1.4M LDD-LiNO of comparative example 5 3 +5% FEC as a clear solution, 1.4M LDD-Li of comparative example 3 2 O+5% FEC and 1.4M LDD-Li of comparative example 4 2 CO 3 +5% fec was suspension.
The optical properties of the optical fiber were measured using Raman, FTIR, 7 li Nuclear Magnetic Resonance (NMR) method and other methods have studied that the addition of inorganic additives to Li in basic ether electrolyte + The solvation environment was affected and the results are shown in figure 3. As can be seen from FIG. 3 a, there is a stronger Li in the 1.4M LDD+5% FEC + The peak coordinated to the DME solvent is relatively weak in 1.4M LDD-4S+5% FEC. As can be seen from b in FIG. 3, 1351cm in the basic ether electrolyte (LDD) -1 And 1332cm -1 The peak at corresponds to LiTFSI with o=s=o bond break, 1456cm -1 The peak at which is caused by bending vibration of C-H bond in DOL solvent, 1080cm -1 The peak at which corresponds to the C-O bond of the DOL solvent. 1058cm in 1.4MLDD-4S+5% FEC of example 1 -1 And 1186/1104cm -1 The peaks at these correspond to S-N-S and C-F bond cleavage of LiTFSI, respectively. 849cm in 1.4M LDD+5% FEC and 1.4M LDD-4S+5% FEC electrolyte -1 The peak at free DME is reduced due to the addition of the lithium-containing compound as an inorganic additive, allowing electrolysisThe concentration of lithium ions in the liquid increases, resulting in more DME and Li + Coordination. Correspondingly, 867cm -1 Li at + The coordination peak with DME was enhanced in 1.4M LDD+5% FEC, while the increase in 1.4MLDD-4S+5% FEC was less, indicating Li in 1.4M LDD-4S+5% FEC + Interaction with DME solvent is weak. As can be seen from FIG. 3c, the nuclear magnetic pattern of 1.4M LDD-4S+5% FEC compared with that of LDD, and the 1.4M LDD-4S+5% FEC has a chemical shift in Li forward direction, further demonstrating that the addition of various inorganic additives causes Li to be + The interaction with the solvent is reduced and the interaction with the anion is enhanced.
According to the invention, the solvation structure of the basic ether electrolyte is changed by adding the inorganic additive into the basic ether electrolyte, and Li is weakened after the nano lithium oxide, the nano lithium fluoride, the nano lithium carbonate and the nano lithium nitrate are dissociated + Coordination of the solvent, therefore, the high entropy suspension ether electrolyte of the invention forms a weak solvating environment.
Performance tests were performed on the lithium ion batteries of example 1 and comparative examples 1 to 10:
(1) Cyclic voltammetry testing of lithium ion batteries
The test voltage range of the graphite half-cell is 0.005-2.0V vs Li/Li + The scanning speed is 0.1-20 mV.s -1 The test temperature was room temperature.
(2) Room temperature and low Wen Hengliu charge-discharge test of lithium ion batteries:
the half-cell test voltage range is 0.005-2.0V vs Li/Li + The test current density was 0.1 to 3C (1C=372 mA. G -1 ) The test temperature was 25 ℃. The test voltage range of the graphite and lithium iron phosphate full battery is 2.0-3.65V vs Li/Li + The scanning speed is 0.1-20 mV.s -1 The test current density was 0.1 to 5C (1C=170mAh.g) -1 ) The test temperature is 25 ℃, -10 ℃, -20 ℃, -30 ℃, the test is started after standing for 1h under each temperature condition in the low-temperature test, and the test is started after circulating for 3 weeks under the current density of 0.1 ℃ before the cycle performance test.
(3) Impedance EIS test of lithium ion battery
The test voltage range is 0.005-2.0V vs Li/Li + The test range of the frequency is 0.01-100000 Hz. And standing for 10 hours after the lithium ion battery is assembled, and testing the impedance before the cycle. The impedance after the test cycle of the battery after 5 weeks of charge and discharge at 0.1C magnification.
FIG. 4 a shows that the ionic conductivity of LDD at room temperature is 8.73mS/cm and that of 1.4MLDD-4S+5% FEC is 7.99mS/cm. Study of Li in LDD and 1.4M LDD-4S+5% FEC by fitting Electrochemical Impedance Spectra (EIS) of fresh Li symmetrical cells at different temperatures + The desolvation barrier of (c) (the results are shown in fig. 4 b, c). Fitting EIS spectra according to classical Arrhenius law (formula 1) to obtain activation energy and desolvation energy of lithium ions in different electrolytes penetrating through SEI films.
In the formula (1), k is a rate constant, T is a thermodynamic temperature, R ct/SEI Is ion transfer resistance, A is pre-finger constant, E a For activation energy, R is the standard gas constant. By fitting the separate semicircles (R SEI ，R ct ) Obtaining activation energy E a ,R SEI Representing Li + Resistance across SEI at intermediate frequency; r is R ct Representing Li at a lower frequency at SEI/electrolyte interface + Is provided. According to the fitted R SEI And R is ct The corresponding activation energy E is obtained by the Arrhenius equation a . As shown in b, c in fig. 4, the fitting calculation shows that the activation energy in 1.4M LDD-4s+5% fec is lower than the higher SEI film resistance in LDD, which indicates that the SEI film formed by 1.4M LDD-4s+5% fec can significantly reduce the diffusion resistance of lithium ions and accelerate the diffusion kinetics of lithium ions. In addition, several anions can participate in the solvation layer of lithium ions to replace part of solvent molecules, thereby reducing desolvation energy of lithium ions.
Thus, the ionic conductivity of 1.4M LDD-4S+5% FEC prepared in example 1 of the present invention was lower than that of the base electrolyte LDD, but 1.4M LDD-4S+5% FEC was electrolyzedThe activation energy in both the diffusion process and the charge transfer process is lower, thereby having better Li + Dynamics.
Fig. 5 is a charge-discharge graph of the lithium ion battery DII-1, and fig. 6 is a CV graph and a dQ/dV differential capacity graph of the lithium ion batteries DII-1 and II-1, and it can be seen from fig. 5 and 6 that the graphite negative electrode is not compatible with the graphite negative electrode because the graphite negative electrode is susceptible to solvent co-intercalation in the basic ether electrolyte (LDD), and subsequent decomposition is susceptible to exfoliation of the graphite structure, resulting in a decrease in capacity and cycle stability.
FIG. 7 is an EIS diagram of lithium ion batteries DII-1 and II-1, as can be seen: compared to LDD,1.4M LDD-4S+5% FEC has lower resistance. FIG. 8 a shows the charge and discharge curves of the lithium ion battery II-1, FIG. 8 b shows the rate performance graphs of the lithium ion batteries DII-1 and II-1, and FIG. 8c shows the cycle performance graphs of the lithium ion batteries DII-1 and II-1, as can be seen from FIG. 8, the cycle performance graph of the lithium ion battery DII-1 and II-1 is shown in 1MLiTFSI+DOL/DME+2% LiNO 3 The addition of 4 inorganic additives to (LDD) gives 1.4MLDD-4S+5% FEC having excellent electrochemical properties, and no solvent co-intercalation phenomenon typical of the base ether electrolyte, compared with LDD,1.4M LDD-4S+5% FEC having excellent electrochemical properties, the capacities at current densities of 0.1C, 0.2C, 0.5C, 1C, 2C, 3C being 360mA h.g, respectively -1 、346mAh·g -1 、324mAh·g -1 、280mAh·g -1 、221mAh·g -1 And 165 mAh.g-1.
FIG. 9 is a graph showing charge and discharge at a current density of 0.1C for lithium ion batteries DII-7, DII-8, DII-9, and DII-10, and FIG. 10 is a graph showing cycle performance and coulombic efficiency for lithium ion batteries II-1, DII-7, DII-8, DII-9, and DII-10, as can be seen from FIGS. 9 and 10, when a single inorganic additive is added to a basic ether electrolyte (LDD), there is a similar solvent co-intercalation phenomenon as in the LDD and a lower capacity is exhibited, and only 50 mAh.g at 1C -1 Left and right capacity.
In fig. 11, a is a charge-discharge graph of the lithium ion battery DII-6, and b is a rate performance graph of the lithium ion batteries DII-6 and II-1, and as can be seen from fig. 11, a stable SEI film can be formed by adding the organic additive FEC to the basic ether electrolyte.
FIG. 12 is a graph showing the rate performance of lithium ion batteries DII-2, DII-3, DII-4, and DII-5, FIG. 12 shows the lithium ion battery at 1.4M LDD-Li 2 O+5％FEC、1.4M LDD-Li 2 CO 3 +5％FEC，1.4M LDD-LiF+5％FEC，1.4M LDD-LiNO 3 Electrochemical performance in +5% FEC electrolyte, it was found that FEC combined with a single inorganic additive is effective in inhibiting solvent co-intercalation, but the rate capability is still inferior to that of 1.4M LDD-4S+5% FEC, therefore, the present invention can effectively improve the electrochemical performance of graphite negative electrode by adding several inorganic additives and organic additives to LDD at the same time.
The invention tests the low temperature performance of the lithium ion batteries DII-1 and II-1, and the test process is as follows: lithium ion batteries DII-1 and II-1 were cycled at-10deg.C to form SEI, the results are shown in FIG. 13. As can be seen from FIG. 13, the lithium ion battery DII-1 shows extremely low capacity at-10℃and, in addition, almost no capacity at-20, -30℃while the lithium ion battery II-1 shows nearly 300 mAh.g -1 This demonstrates that the addition of several inorganic additives promotes the rapid formation of stable SEI even at low temperatures, and low desolvation enables it to exhibit excellent rate performance.
From the above embodiments, the present invention provides a high-entropy suspension ether electrolyte and a lithium ion battery thereof, wherein the high-entropy suspension ether electrolyte comprises the following raw materials: a base ether electrolyte, an organic additive and an inorganic additive; wherein the inorganic additive is a mixture of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and lithium nitrate. According to the invention, the inorganic additive and the organic additive are added into the basic ether electrolyte, and the stable SEI film can be formed by the synergistic effect of the organic additive and the inorganic additive, so that the activation energy in the diffusion process and the charge transfer process of the electrolyte is reduced, the diffusion resistance of lithium ions is obviously reduced, the diffusion kinetics of the lithium ions is accelerated, and the electrochemical performance and the low-temperature performance of the lithium ion battery are improved.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The high-entropy suspension ether electrolyte is characterized by comprising the following raw materials: a base ether electrolyte, an organic additive and an inorganic additive; the inorganic additive is a mixture of nano lithium oxide, nano lithium fluoride, nano lithium carbonate and nano lithium nitrate.
2. The high entropy suspension ether electrolyte according to claim 1, wherein the base ether electrolyte consists of an ether solvent, a halogen-containing lithium salt and lithium nitrate.
3. The high entropy suspension ether electrolyte according to claim 2, wherein the ether solvent comprises one or more of ethylene glycol dimethyl ether, 1, 3-dioxolane, tetraethylene glycol dimethyl ether, 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether.
4. The high-entropy suspension ether electrolyte according to claim 2 or 3, wherein the halogen-containing lithium salt comprises one or more of lithium hexafluorophosphate, lithium bistrifluoro-methanesulfonimide, lithium bistrifluoro-sulfimide, lithium perchlorate, lithium difluorooxalato-borate and lithium tetrafluoroborate.
5. The high-entropy suspension ether electrolyte according to claim 4, wherein the concentration of lithium ions in the base ether electrolyte is 0.5 to 2mol/L; in the basic ether electrolyte, the mass of lithium nitrate is 1-3% of the total mass of the basic ether electrolyte.
6. The high entropy suspension ether electrolyte according to claim 1 or 2, characterized in that the organic additive comprises fluoroethylene carbonate and/or vinylene carbonate.
7. The high entropy suspension ether electrolyte according to claim 6, wherein the volume of the organic additive is 3 to 7% of the total volume of the high entropy suspension ether electrolyte.
8. The high-entropy suspension ether electrolyte according to claim 1, wherein the concentration of nano lithium oxide, lithium fluoride, nano lithium carbonate and lithium nitrate in the high-entropy suspension ether electrolyte is independently 0.05 to 0.5mol/L.
9. A lithium ion battery, characterized in that the lithium ion battery comprises a positive electrode, a negative electrode, a separation film and the high-entropy suspension ether electrolyte as claimed in any one of claims 1 to 8.
10. The lithium ion battery of claim 9, wherein the positive electrode comprises a positive electrode current collector and a positive electrode membrane, and the negative electrode comprises a negative electrode current collector and a negative electrode membrane; the positive electrode membrane comprises a positive electrode active material, a conductive agent and a binder; the negative electrode membrane includes a negative electrode active material, a conductive agent, and a binder.
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