CN117096472A - Negative electrode piece for pre-supplementing lithium, preparation method of negative electrode piece, secondary battery and electronic device - Google Patents
Negative electrode piece for pre-supplementing lithium, preparation method of negative electrode piece, secondary battery and electronic device Download PDFInfo
- Publication number
- CN117096472A CN117096472A CN202311211828.7A CN202311211828A CN117096472A CN 117096472 A CN117096472 A CN 117096472A CN 202311211828 A CN202311211828 A CN 202311211828A CN 117096472 A CN117096472 A CN 117096472A
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- China
- Prior art keywords
- negative electrode
- lithium
- secondary battery
- supplementing
- compound
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 196
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 194
- 238000002360 preparation method Methods 0.000 title claims abstract description 42
- 230000001502 supplementing effect Effects 0.000 title claims description 92
- 239000007773 negative electrode material Substances 0.000 claims abstract description 42
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 239000002184 metal Substances 0.000 claims abstract description 15
- 238000011282 treatment Methods 0.000 claims description 65
- 238000003825 pressing Methods 0.000 claims description 54
- 150000001875 compounds Chemical class 0.000 claims description 36
- 238000000034 method Methods 0.000 claims description 35
- 229940126062 Compound A Drugs 0.000 claims description 29
- NLDMNSXOCDLTTB-UHFFFAOYSA-N Heterophylliin A Natural products O1C2COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC2C(OC(=O)C=2C=C(O)C(O)=C(O)C=2)C(O)C1OC(=O)C1=CC(O)=C(O)C(O)=C1 NLDMNSXOCDLTTB-UHFFFAOYSA-N 0.000 claims description 29
- 239000010405 anode material Substances 0.000 claims description 22
- 239000013589 supplement Substances 0.000 claims description 22
- 238000001035 drying Methods 0.000 claims description 18
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 239000002033 PVDF binder Substances 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 11
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 11
- 125000000217 alkyl group Chemical group 0.000 claims description 10
- 125000001153 fluoro group Chemical group F* 0.000 claims description 10
- 239000010439 graphite Substances 0.000 claims description 9
- 229910002804 graphite Inorganic materials 0.000 claims description 9
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 9
- 229910021385 hard carbon Inorganic materials 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 6
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 claims description 6
- 125000001424 substituent group Chemical group 0.000 claims description 6
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 5
- 229910052731 fluorine Inorganic materials 0.000 claims description 5
- 239000003575 carbonaceous material Substances 0.000 claims description 4
- 235000013024 sodium fluoride Nutrition 0.000 claims description 4
- 239000011775 sodium fluoride Substances 0.000 claims description 4
- ODNBVEIAQAZNNM-UHFFFAOYSA-N 1-(6-chloroimidazo[1,2-b]pyridazin-3-yl)ethanone Chemical compound C1=CC(Cl)=NN2C(C(=O)C)=CN=C21 ODNBVEIAQAZNNM-UHFFFAOYSA-N 0.000 claims description 3
- GUNJVIDCYZYFGV-UHFFFAOYSA-K Antimony trifluoride Inorganic materials F[Sb](F)F GUNJVIDCYZYFGV-UHFFFAOYSA-K 0.000 claims description 3
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 3
- 235000003270 potassium fluoride Nutrition 0.000 claims description 3
- 239000011698 potassium fluoride Substances 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 45
- 229910001416 lithium ion Inorganic materials 0.000 description 45
- 239000000243 solution Substances 0.000 description 34
- 238000012360 testing method Methods 0.000 description 25
- 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 23
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 21
- 239000007774 positive electrode material Substances 0.000 description 20
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- 230000002035 prolonged effect Effects 0.000 description 7
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- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
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- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 4
- 150000002642 lithium compounds Chemical class 0.000 description 4
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 4
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- 229910052796 boron Inorganic materials 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- LEGITHRSIRNTQV-UHFFFAOYSA-N carbonic acid;3,3,3-trifluoroprop-1-ene Chemical compound OC(O)=O.FC(F)(F)C=C LEGITHRSIRNTQV-UHFFFAOYSA-N 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- OPHUWKNKFYBPDR-UHFFFAOYSA-N copper lithium Chemical compound [Li].[Cu] OPHUWKNKFYBPDR-UHFFFAOYSA-N 0.000 description 1
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 description 1
- IUYOGGFTLHZHEG-UHFFFAOYSA-N copper titanium Chemical compound [Ti].[Cu] IUYOGGFTLHZHEG-UHFFFAOYSA-N 0.000 description 1
- 150000005676 cyclic carbonates Chemical class 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- SNQXJPARXFUULZ-UHFFFAOYSA-N dioxolane Chemical compound C1COOC1 SNQXJPARXFUULZ-UHFFFAOYSA-N 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- VUPKGFBOKBGHFZ-UHFFFAOYSA-N dipropyl carbonate Chemical compound CCCOC(=O)OCCC VUPKGFBOKBGHFZ-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- VCYZVXRKYPKDQB-UHFFFAOYSA-N ethyl 2-fluoroacetate Chemical compound CCOC(=O)CF VCYZVXRKYPKDQB-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- CYEDOLFRAIXARV-UHFFFAOYSA-N ethyl propyl carbonate Chemical compound CCCOC(=O)OCC CYEDOLFRAIXARV-UHFFFAOYSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- IFYYFLINQYPWGJ-VIFPVBQESA-N gamma-Decalactone Natural products CCCCCC[C@H]1CCC(=O)O1 IFYYFLINQYPWGJ-VIFPVBQESA-N 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
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- 229910021389 graphene Inorganic materials 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
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- 229940017219 methyl propionate Drugs 0.000 description 1
- KKQAVHGECIBFRQ-UHFFFAOYSA-N methyl propyl carbonate Chemical compound CCCOC(=O)OC KKQAVHGECIBFRQ-UHFFFAOYSA-N 0.000 description 1
- AHADSRNLHOHMQK-UHFFFAOYSA-N methylidenecopper Chemical compound [Cu].[C] AHADSRNLHOHMQK-UHFFFAOYSA-N 0.000 description 1
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- 239000002048 multi walled nanotube Substances 0.000 description 1
- 229910021392 nanocarbon Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
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- 239000002985 plastic film Substances 0.000 description 1
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- 229920000123 polythiophene Polymers 0.000 description 1
- 229920001289 polyvinyl ether Polymers 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
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- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
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- 239000004759 spandex Substances 0.000 description 1
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- 238000010998 test method Methods 0.000 description 1
- ZUHZGEOKBKGPSW-UHFFFAOYSA-N tetraglyme Chemical compound COCCOCCOCCOCCOC ZUHZGEOKBKGPSW-UHFFFAOYSA-N 0.000 description 1
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
-
- 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
Abstract
The application provides a pre-lithium negative electrode plate, a preparation method thereof, a secondary battery and an electronic device, wherein the pre-lithium negative electrode plate comprises a negative electrode current collector and a negative electrode material layer positioned on at least one surface of the negative electrode current collector, the secondary battery is formed by taking metal lithium as a counter electrode and the pre-lithium negative electrode plate, and the potential of the secondary battery is 0.2V to 1V. With the above arrangement, the secondary battery obtained has a high energy density and a long cycle life.
Description
Technical Field
The application relates to the technical field of electrochemistry, in particular to a negative electrode plate for pre-supplementing lithium, a preparation method of the negative electrode plate, a secondary battery and an electronic device.
Background
The lithium ion battery has the characteristics of large specific energy, high working voltage, low self-discharge rate, small volume, light weight and the like, and has wide application in the field of portable consumer electronics. With the recent rapid development of electric vehicles and mobile electronic devices, the requirements of lithium ion batteries for energy density and cycle life are increasing.
Graphite is currently the most widely used negative electrode active material, and has the advantages of high efficiency, stable charge and discharge and the like, but the lower capacity (372 mAh/g) and potential safety hazard of lithium dendrites prevent further application. Compared with graphite, the novel negative electrode active material such as silicon, hard carbon and the like is considered to be the most promising lithium battery negative electrode material capable of replacing or partially replacing graphite due to the characteristics of higher gram capacity, proper charge and discharge potential and the like. However, the low first efficiency severely restricts the large-scale application of the novel negative electrode active materials such as silicon or hard carbon and the composite active materials of the novel negative electrode active materials and graphite in lithium ion batteries.
Disclosure of Invention
In view of the problem of low first efficiency of novel anode active materials such as silicon or hard carbon, the application aims to provide an anode piece for pre-supplementing lithium, a preparation method of the anode piece, a secondary battery and an electronic device, so as to improve the first efficiency of the anode piece, the energy density of the secondary battery and the cycle life of the secondary battery. The specific technical scheme is as follows:
in the context of the present application, the present application is explained by taking a lithium ion battery as an example of a secondary battery, but the electrochemical device of the present application is not limited to a lithium ion battery.
The first aspect of the application provides a negative electrode plate for pre-lithium supplement, which comprises a negative electrode current collector and a negative electrode material layer positioned on at least one surface of the negative electrode current collector, wherein metal lithium is used as a counter electrode to form a secondary battery with the negative electrode plate for pre-lithium supplement, and the potential of the secondary battery is 0.2V to 1V, preferably 0.29V to 0.8V. The primary efficiency of the negative electrode plate can be improved by pre-supplementing lithium to the negative electrode plate and regulating and controlling the potential of the secondary battery formed by taking metal lithium as a counter electrode within the range of the application, and the irreversible capacity loss caused by the fact that lithium of the positive electrode plate is used for supplementing the negative electrode is reduced, so that the energy density of the secondary battery is improved. In addition, as the metal lithium enters the negative electrode plate in advance, lithium in the secondary battery is increased, and the cycle life of the secondary battery can be prolonged in the cycle process. In combination, the lithium-pre-filled negative electrode plate has higher first efficiency, and the lithium-pre-filled negative electrode plate is applied to a secondary battery, so that the obtained secondary battery has higher energy density and longer cycle life.
In one embodiment of the present application, the anode material layer includes a compound a including at least one of a compound represented by formula (I) or formula (II):
Wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 Alkyl, -F; c (C) 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms; the mass percentage of the compound a is 0.01% to 0.1% based on the mass of the anode material layer. According to the application, the lithium is pre-supplemented to the negative electrode plate by using the pre-lithium supplementing compound containing the compound A and the lithium source, so that the degree of pre-lithium supplementation of the negative electrode plate is improved, the first efficiency of the negative electrode plate is further improved, and the energy density of the secondary battery is correspondingly improved. The mass percent of the regulating compound A is in the range of the application, which is beneficial to the high primary efficiency of the negative electrode plate, thereby improving the energy density of the secondary battery and prolonging the cycle life of the secondary battery.
In one embodiment of the present application, the anode material layer includes an anode active material including at least one of hard carbon, graphite, a silicon oxygen material, or a silicon carbon material. The negative electrode active material of the type is favorable for improving the conductivity of the negative electrode plate, so that the cycling stability of the negative electrode plate is improved, and the cycling performance of the secondary battery is further improved.
In one embodiment of the present application, the thickness of the anode material layer is 30 μm to 100 μm. The thickness of the anode material layer is regulated within the range, so that higher capacity is provided for the anode material layer, and the energy density of the secondary battery is improved.
In one embodiment of the present application, the porosity of the anode material layer is 20% to 45%. The porosity of the negative electrode material layer is regulated and controlled within the range, so that the lithium ions are favorably embedded and separated in the negative electrode material layer, the first efficiency of the negative electrode plate is improved, the energy density of the secondary battery is improved, and the cycle life of the secondary battery is prolonged.
In one embodiment of the application, the anode piece of the pre-lithium supplement is 1350cm -1 To 1450cm -1 There is a characteristic peak in between. The compound A containing the biphenyl structure exists in the negative pole piece of the pre-filling lithium, so that the negative pole piece of the pre-filling lithium has the advantages of improved first efficiency, energy density and cycle life.
The second aspect of the application provides a preparation method of a negative electrode plate for pre-supplementing lithium, which comprises the following steps: carrying out primary cold pressing treatment on the negative electrode piece, immersing the negative electrode piece subjected to primary cold pressing treatment in lithium supplementing solution for carrying out pre-lithium supplementing treatment, cleaning and drying the negative electrode piece subjected to pre-lithium supplementing treatment, and carrying out secondary cold pressing treatment on the dried negative electrode piece to obtain the negative electrode piece subjected to pre-lithium supplementing; wherein the pressure of the first cold pressing treatment is 0.01 ton to 1 ton, and the pressure of the second cold pressing treatment is 1 ton to 30 tons; the pre-lithium supplementing solution comprises a pre-lithium supplementing compound, wherein the pre-lithium supplementing compound comprises a lithium source and a compound A, and the compound A comprises at least one of compounds shown in a formula (I) or a formula (II);
Wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 An alkyl group or a fluorine atom; c (C) 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms; the mass percentage of the pre-lithium supplementing compound is 5-30% based on the mass of the lithium supplementing solution. The pre-lithium supplementing compound comprises a lithium source and a compound A, wherein the compound A converts the lithium source into a liquid state with strong reducibility, and the lithium supplementing degree of the negative electrode plate can be improved by pre-supplementing lithium to the negative electrode plate, so that the energy density of the secondary battery can be improved, and the cycle life of the secondary battery can be prolonged.
In one embodiment of the present application, the lithium supplementing solution further includes a fluoride including at least one of polyvinylidene fluoride, lithium fluoride, sodium fluoride, potassium fluoride, or antimony trifluoride, and the mass percentage of the fluoride is 0.1% to 20% based on the mass of the lithium supplementing solution. The mass percentage content of fluoride is regulated and controlled within the range of the application, which is beneficial to the preforming of the solid electrolyte membrane on the surface of the negative electrode plate, so that the surface of the negative electrode active material in the negative electrode plate is more stable, and the cycle performance of the secondary battery is improved.
In one embodiment of the application, the porosity ρ of the negative electrode sheet after the first cold pressing treatment 1 30 to 60 percent of porosity ρ of the negative electrode piece of the pre-lithium supplement after the second cold pressing treatment 2 10 to 50 percent, 5 percent or less rho 1 -ρ 2 Less than or equal to 30 percent. By subjecting the negative electrode sheet after the first cold pressing treatment to a porosity ρ 1 Porosity ρ of the lithium-pre-supplemented negative electrode sheet after the second cold press treatment 2 And ρ 1 -ρ 2 The porosity of the negative electrode plate after the first cold pressing treatment is larger, which is beneficial to improving the lithium supplementing efficiency of the negative electrode plate, and the porosity of the negative electrode plate after the second cold pressing treatment is smaller, which is beneficial to improving the compaction density of the negative electrode plate, thereby improving the energy density of the secondary battery and prolonging the cycle life of the secondary battery.
A third aspect of the present application provides a secondary battery comprising a positive electrode tab, a separator, and a negative electrode tab of the pre-lithium supplement of any of the foregoing embodiments. The negative electrode plate of the pre-lithium-supplementing electrode has higher first-time efficiency and compaction density, so that the secondary battery has higher energy density and longer cycle life.
A fourth aspect of the present application provides an electronic device comprising the secondary battery according to any one of the foregoing embodiments. The secondary battery of the present application has a high energy density and a long cycle life, and therefore the electronic device of the present application has a long service life.
The application has the beneficial effects that:
the application provides a pre-lithium negative electrode plate, a preparation method thereof, a secondary battery and an electronic device, wherein the pre-lithium negative electrode plate comprises a negative electrode current collector and a negative electrode material layer positioned on at least one surface of the negative electrode current collector, the secondary battery is formed by taking metal lithium as a counter electrode and the pre-lithium negative electrode plate, and the potential of the secondary battery is 0.2V to 1V. The primary efficiency of the negative electrode plate can be improved by pre-supplementing lithium to the negative electrode plate and regulating and controlling the potential of the secondary battery formed by taking metal lithium as a counter electrode within the range of the application, and the irreversible capacity loss caused by the fact that lithium of the positive electrode plate is used for supplementing the negative electrode is reduced, so that the energy density of the secondary battery is improved. In addition, as the metal lithium enters the negative electrode plate in advance, lithium in the secondary battery is increased, and the cycle life of the secondary battery can be prolonged in the cycle process. In combination, the lithium-pre-filled negative electrode plate has higher first efficiency, and the lithium-pre-filled negative electrode plate is applied to a secondary battery, so that the obtained secondary battery has higher energy density and longer cycle life.
Of course, it is not necessary for any one product or method of practicing the application to achieve all of the advantages set forth above at the same time.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the application, and other embodiments may be obtained according to these drawings to those skilled in the art.
FIG. 1 is a schematic diagram of a pre-lithium supplementing process of a negative electrode plate in the application;
FIG. 2 is a charge-discharge curve of the 1 st time of the present application of example 1-1 and comparative example 1-1;
FIG. 3 is a cross-sectional electron microscope of the negative electrode tab of the pre-lithium-ion battery of example 1-1 of the present application;
FIG. 4 is an infrared spectrum of example 1-1 and comparative example 1-1 of the present application.
Reference numerals: unreeling device 01; a first cold pressing device 02; a lithium supplementing reagent pool 03; a cleaning pool 04; a drying device 05; a second cold pressing device 06; and a winding device 07.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments obtained by the person skilled in the art based on the present application fall within the scope of protection of the present application.
In the context of the present application, the present application is explained by taking a lithium ion battery as an example of a secondary battery, but the electrochemical device of the present application is not limited to a lithium ion battery.
The first aspect of the present application provides a negative electrode tab for pre-lithium, comprising a negative electrode current collector and a negative electrode material layer on at least one surface of the negative electrode current collector, wherein when lithium metal is used as a counter electrode to form a secondary battery with the negative electrode tab for pre-lithium, the potential of the secondary battery is 0.2V to 1V, preferably 0.29V to 0.8V, for example, the potential of the secondary battery is 0.2V, 0.29V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1V or a range of any two values thereof. According to the application, after the negative electrode piece is subjected to pre-lithium supplement, the metal lithium is pre-embedded into the negative electrode piece, so that the potential of the negative electrode piece subjected to pre-lithium supplement in a secondary battery formed by taking the metal lithium as a counter electrode is not more than 1V. By pre-supplementing lithium to the negative electrode plate, the metal lithium is pre-inserted into the negative electrode plate, so that the potential of the secondary battery formed by taking the metal lithium as a counter electrode is reduced, and the regulation and control are within the scope of the application, on one hand, the first efficiency of the negative electrode plate can be improved, further, the irreversible capacity loss caused by the fact that the lithium of the positive electrode plate is used for supplementing the negative electrode is reduced, the use of the positive electrode plate in the secondary battery is reduced, and the energy density of the secondary battery is improved. On the other hand, in the cycle of the secondary battery, the structural change of the positive electrode active material and/or the negative electrode active material, which is substantially a decrease in metallic lithium, may lead to an attenuation in the cycle life of the secondary battery, and the metallic lithium is advanced into the negative electrode tab, so that lithium in the secondary battery is increased, and in the cycle, the cycle life of the secondary battery can be prolonged. In combination, the lithium-pre-filled negative electrode plate has higher first efficiency, and the lithium-pre-filled negative electrode plate is applied to a secondary battery, so that the obtained secondary battery has higher energy density and longer cycle life. In the present application, the electrolyte in the secondary battery composed of the metallic lithium as the counter electrode and the negative electrode tab of the pre-lithium supplement may be composed of ethylene carbonate, diethyl carbonate and lithium hexafluorophosphate, wherein the mass percentage of ethylene carbonate is 43.75%, the mass percentage of diethyl carbonate is 43.75% and the mass percentage of lithium hexafluorophosphate is 12.5% based on the mass of the electrolyte.
In one embodiment of the present application, the anode material layer includes a compound a including at least one of a compound represented by formula (I) or formula (II):
wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 Alkyl, -F; c (C) 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms. For example, compound A includes biphenyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, 3' -dimethylbiphenylAt least one of phenylbiphenyl, 2-ethylbiphenyl, triethylbiphenyl, 3 '-difluorobiphenyl, 4' -dimethylbiphenyl, 3', 4' -dimethylbiphenyl, 4 '-methyl-3-fluorobiphenyl, naphthalene, 2-methylnaphthalene, 2'7-dimethylnaphthalene, or 2-fluoronaphthalene. The mass percentage of the compound a is 0.01% to 0.1% based on the mass of the anode material layer. For example, the mass percentage of the compound A is 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1% or a range of any two values therein. According to the application, the lithium supplementing effect of the negative electrode plate is improved together by the pre-supplementing lithium compound containing the compound A and the lithium source, and the mass percent of the compound A is positively correlated with the content of lithium entering the negative electrode plate, namely, the higher the pre-supplementing lithium degree is in the same negative electrode plate system, the higher the mass percent of the compound A is, the higher the first efficiency of the negative electrode plate is, and the higher the energy density of the corresponding secondary battery is. The mass percent of the regulating compound A is in the range of the application, which is beneficial to the high conductivity of the negative electrode plate and the high first efficiency, thereby improving the energy density of the secondary battery and prolonging the cycle life of the secondary battery.
In one embodiment of the present application, the anode material layer includes an anode active material including at least one of hard carbon, graphite, a silicon oxygen material, or a silicon carbon material. The negative electrode active material of the type is selected to be beneficial to improving the conductivity of the negative electrode plate, and in addition, the lithium is supplemented in advance, so that the cycle stability of the negative electrode plate is improved, and the cycle performance of the secondary battery is further improved.
In one embodiment of the present application, the thickness of the anode material layer is 30 μm to 100 μm. For example, the thickness of the anode material layer is 30 μm, 40 μm, 60 μm, 80 μm, 100 μm or a range of any two numerical values therein. Through regulating and controlling the thickness of the negative electrode material layer within the range, more lithium ions can be fully supplemented in the negative electrode material layer, so that higher first efficiency is provided for the negative electrode material layer, and the energy density of the secondary battery is improved.
In one embodiment of the present application, the porosity of the anode material layer is 20% to 45%. For example, the porosity of the anode material layer is 20%, 25%, 30%, 35%, 40%, 45%, or a range of any two values therein. The porosity of the negative electrode material layer is regulated and controlled within the range, so that the lithium ions are favorably embedded into and separated from the negative electrode material layer, and the negative electrode plate has higher first efficiency, thereby improving the energy density of the secondary battery and prolonging the cycle life of the secondary battery.
In one embodiment of the application, the anode piece of the pre-lithium supplement is 1350cm -1 To 1450cm -1 There is a characteristic peak in between. At 1350cm -1 To 1450cm -1 The characteristic peak exists, which indicates that the negative electrode plate of the pre-filling lithium has the compound A containing the biphenyl structure, and a small amount of the compound A can be adsorbed on the negative electrode plate when the negative electrode plate is subjected to the pre-filling lithium, and the mass percent of the compound A is positively correlated with the content of the lithium entering the negative electrode plate, so that the first efficiency, the energy density and the cycle life of the negative electrode plate of the pre-filling lithium are improved.
In the present application, the "anode material layer on at least one surface of the anode current collector" means that the anode material layer may be on one surface of the anode current collector in the thickness direction thereof, or may be on both surfaces of the anode current collector in the thickness direction thereof. The "surface" here may be the entire area of the surface of the negative electrode current collector or may be a partial area of the surface of the negative electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The negative electrode current collector is not particularly limited as long as the object of the present application can be achieved. For example, the negative electrode current collector may include a copper foil, a copper alloy foil, a nickel foil, a stainless steel foil, a titanium foil, nickel foam, copper foam, or a composite current collector (e.g., a lithium copper composite current collector, a carbon copper composite current collector, a nickel copper composite current collector, a titanium copper composite current collector, etc.), or the like. In the present application, the thickness of the negative electrode current collector and the negative electrode material layer is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 20 μm, and the thickness of the negative electrode material layer is 30 μm to 130 μm. Optionally, the anode material layer may further include a conductive agent and an anode binder. The kind of the conductive agent in the anode material layer is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), carbon Nanotubes (CNTs), carbon fiber, crystalline flake graphite, ketjen black, graphene, a metallic material, or a conductive polymer. The carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes. The carbon fibers may include, but are not limited to, vapor Grown Carbon Fibers (VGCF) and/or nano carbon fibers. The above-mentioned metal material may include, but is not limited to, metal powder and/or metal fiber, and in particular, the metal may include, but is not limited to, at least one of copper, nickel, aluminum or silver. The conductive polymer may include, but is not limited to, at least one of a polyphenylene derivative, polyaniline, polythiophene, polyacetylene, or polypyrrole. The kind of the anode binder in the anode material layer is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the anode binder may include, but is not limited to, at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene.
The preparation method of the negative electrode piece before pre-lithium supplementation is not particularly limited, so long as the purpose of the application can be achieved. For example, the preparation method of the negative electrode sheet may include, but is not limited to, the following steps: mixing a negative electrode active material, a conductive agent and a negative electrode binder according to a mass ratio to prepare a negative electrode slurry; coating the negative electrode slurry on one surface of a negative electrode current collector, and drying to form a negative electrode material layer on one surface of the negative electrode current collector; and coating the negative electrode slurry on the other surface of the negative electrode current collector, and after drying, forming negative electrode material layers on the two surfaces of the negative electrode current collector respectively to obtain the negative electrode plate before pre-lithium supplementation. The mass ratio of the anode active material, the conductive agent, and the anode binder in the anode material layer is not particularly limited as long as the object of the present application can be achieved. The solid content of the anode slurry is not particularly limited in the present application as long as the object of the present application can be achieved, for example, the solid content of the anode slurry is 30% to 75%. The drying time and temperature of the present application are not particularly limited as long as the object of the present application can be achieved. The process parameters of cold pressing are not particularly limited in the present application as long as the object of the present application can be achieved. The present application is not particularly limited in the size of the cut pieces and the slit, and those skilled in the art can perform the cut pieces and the slit according to actual circumstances as long as the object of the present application can be achieved. The drying time and temperature of the present application are not particularly limited as long as the object of the present application can be achieved.
The second aspect of the application provides a preparation method of a negative electrode plate for pre-supplementing lithium, which comprises the following steps: carrying out primary cold pressing treatment on the negative electrode piece, immersing the negative electrode piece subjected to primary cold pressing treatment in lithium supplementing solution for carrying out pre-lithium supplementing treatment, cleaning and drying the negative electrode piece subjected to pre-lithium supplementing treatment, and carrying out secondary cold pressing treatment on the dried negative electrode piece to obtain the negative electrode piece subjected to pre-lithium supplementing; wherein the pressure of the first cold pressing treatment is 0.01 ton to 1 ton, and the pressure of the second cold pressing treatment is 1 ton to 30 tons; for example, the first cold press treatment may have a pressure of 0.01 ton, 0.1 ton, 0.2 ton, 0.4 ton, 0.6 ton, 0.8 ton, 1 ton, or a range of any two of these values, and the second cold press treatment may have a pressure of 1 ton, 5 ton, 10 ton, 15 ton, 20 ton, 25 ton, 30 ton, or a range of any two of these values.
The pre-lithium supplementing solution comprises a pre-lithium supplementing compound, the pre-lithium supplementing compound comprises a lithium source and a compound A, and the compound A comprises at least one of compounds shown in a formula (I) or a formula (II);
wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 An alkyl group or a fluorine atom; the C is 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms; for example, compound a includes at least one of biphenyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, 3' -dimethylbiphenyl, 2-ethylbiphenyl, triethylbiphenyl, 3' -difluorobiphenyl, 4' -dimethylbiphenyl, 3', 4' -dimethylbiphenyl, 4' -methyl-3-fluorobiphenyl, naphthalene, 2-methylnaphthalene, 2'7-dimethylnaphthalene, or 2-fluoronaphthalene. In the pre-lithium supplementing solution, the compound A and lithium form a binary complex compound, so that a lithium source is converted into a liquid state with strong reducibility, the lithium supplementing effect of the negative electrode plate is improved, and the mass percentage of the pre-lithium supplementing compound is 5-30% based on the mass of the pre-lithium supplementing solution; for example, the mass percent of the pre-lithium compound is 5%, 10%, 15%, 20%, 25%, 30% or a range of any two values therein.
In one embodiment of the application, the mass percentage of compound a is 5% to 20% based on the mass of the lithium-compensating solution. For example, the mass percentage of compound a is 5%, 10%, 15%, 20% or a range of any two values therein.
As shown in fig. 1, the unreeling device 01, the first cold pressing device 02, the lithium-supplementing reagent pool 03, the cleaning pool 04, the drying device 05, the second cold pressing device 06 and the reeling device 07 are combined, and the negative electrode sheet is transported along the W direction. And placing a negative pole piece without lithium supplement on the unreeling device 01, wherein the negative pole piece without lithium supplement comprises a negative pole current collector and a negative pole material layer positioned on at least one surface of the negative pole current collector. And carrying out primary cold pressing treatment on the negative pole piece without lithium supplementation at the primary cold pressing device 02 along the direction of the transmission direction W, and pre-cold pressing and molding the negative pole piece without lithium supplementation. And then immersing the negative electrode piece subjected to the first cold pressing treatment in a lithium supplementing solution of a lithium supplementing reagent pool 03 for pre-supplementing lithium treatment, and controlling the stay time of the negative electrode piece subjected to the first cold pressing treatment in the lithium supplementing reagent pool 03 by adjusting the transmission speed so as to regulate and control the lithium supplementing efficiency of the negative electrode piece. After the impregnation is finished, the negative electrode piece after the pre-lithium supplementing treatment is transmitted to a cleaning pool 04 to clean residual substances in the pre-lithium supplementing process, then the drying device 05 is used for drying residual solvents in the lithium supplementing and cleaning processes, the dried negative electrode piece is subjected to secondary cold pressing treatment at a secondary cold pressing device 06, and the negative electrode piece after the pre-lithium supplementing is shaped; and the winding device 07 recovers the negative electrode plate after the second cold pressing treatment to obtain the negative electrode plate with the pre-lithium supplementing function. The device is a conventional device in the art, and the device adopted in the preparation method of the negative electrode plate for pre-supplementing lithium is not particularly limited, and can be selected by a person skilled in the art according to actual requirements, so long as the purpose of the application can be achieved.
In one embodiment of the application, the dipping time of the negative electrode piece after the first cold pressing treatment in the lithium supplementing reagent pool is 1min to 20min. In one embodiment of the application, the transport speed of the negative electrode sheet is 0.5 m/min to 10 m/min. In one embodiment of the application, the cleaning tank comprises a cleaning agent, and the cleaning agent comprises at least one of ether reagents such as tetrahydrofuran, ethylene glycol dimethyl ether and the like or alcohol solvents. The mass percentage of the pre-lithium-supplementing compound in the lithium-supplementing solution is controlled within the range, and the pre-lithium-supplementing solution has strong reducibility, so that the negative electrode plate subjected to the first cold pressing treatment is beneficial to supplementing more lithium during impregnation. The pressure of the first cold pressing treatment is smaller, the porosity of the obtained negative electrode plate is larger, and the negative electrode plate is immersed in the lithium supplementing solution for pre-supplementing lithium, so that the lithium supplementing efficiency is improved, and the negative electrode plate for pre-supplementing lithium has better first efficiency. The dried negative electrode plate is subjected to secondary cold pressing treatment, namely secondary shaping, the pressure of the secondary cold pressing treatment is high, the porosity of the negative electrode plate can be reduced, the porosity of the negative electrode plate is adjusted to be in a proper interval, the phenomenon of uneven stress in the pre-lithium supplementing process is improved, the electrolyte can infiltrate the negative electrode plate, and meanwhile, the negative electrode plate has high compaction density and good processability, so that the energy density of the secondary battery is improved. By adopting the method to pre-supplement lithium to the negative electrode plate, the energy density of the secondary battery can be improved, and the cycle life of the secondary battery can be prolonged. Wherein the lithium source in the lithium replenishing solution comprises at least one of lithium metal or lithium alloy.
In one embodiment of the present application, the lithium supplementing solution further includes a fluoride including at least one of polyvinylidene fluoride, lithium fluoride, sodium fluoride, potassium fluoride, or antimony trifluoride, and the mass percentage of the fluoride is 0.1% to 20% based on the mass of the lithium supplementing solution. For example, the mass percent of fluoride is 0.1%, 1%, 4%, 8%, 12%, 16%, 20% or ranges of any two values therein. The mass percentage content of fluoride is regulated and controlled within the range of the application, which is beneficial to the preforming of the solid electrolyte membrane on the surface of the negative electrode plate, so that the surface of the negative electrode active material in the negative electrode plate is more stable, and the cycle performance of the secondary battery is improved.
In one embodiment of the application, the porosity ρ of the negative electrode sheet after the first cold pressing treatment 1 30 to 60 percent of porosity ρ of the negative electrode piece of the pre-lithium supplement after the second cold pressing treatment 2 10 to 50 percent, 5 percent or less rho 1 -ρ 2 Less than or equal to 30 percent. For example ρ 1 30%, 35%, 40%, 45%, 50%, 55%, 60% or a range of any two values therein, ρ 2 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or a range of any two values therein, ρ 1 -ρ 2 5%, 10%, 15%, 20%, 25%, 30% or a range of any two values therein. By subjecting the negative electrode sheet after the first cold pressing treatment to a porosity ρ 1 Porosity ρ of the lithium-pre-supplemented negative electrode sheet after the second cold press treatment 2 And ρ 1 -ρ 2 The porosity of the negative electrode plate after the first cold pressing treatment is larger, so that the negative electrode plate after the first cold pressing treatment is beneficial to supplementing enough lithium in a lithium supplementing solution, the lithium supplementing efficiency of the negative electrode plate is improved, the porosity of the negative electrode plate after the second cold pressing treatment is smaller, electrolyte can infiltrate the negative electrode plate, and meanwhile, the negative electrode plate has higher compaction density, so that the energy density of a secondary battery is improved, and the cycle life of the secondary battery is prolonged.
A third aspect of the present application provides a secondary battery comprising a positive electrode tab, a separator, and a negative electrode tab of the pre-lithium supplement of any of the foregoing embodiments. The negative electrode plate of the pre-lithium-supplementing electrode has higher first-time efficiency and compaction density, so that the secondary battery has higher energy density and longer cycle life.
The positive electrode sheet of the present application is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector. The above-mentioned "positive electrode material layer disposed on at least one surface of the positive electrode current collector" means that the positive electrode material layer may be disposed on one surface of the positive electrode current collector in the thickness direction thereof, or may be disposed on both surfaces of the positive electrode current collector in the thickness direction thereof. The "surface" here may be the entire area of the surface of the positive electrode current collector or may be a partial area of the surface of the positive electrode current collector, and the present application is not particularly limited as long as the object of the present application can be achieved. The positive electrode current collector is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode current collector may include an aluminum foil, an aluminum alloy foil, or a composite current collector (e.g., an aluminum carbon composite current collector), or the like. The positive electrode material layer of the present application contains a positive electrode active material, and the present application is not particularly limited in the kind of positive electrode active material as long as the object of the present application can be achieved. For example, the positive electrode active material may include lithium nickel cobalt manganese oxide (NCM 811, NCM622, NCM523, NCM 111), lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide (LiCoO) 2 ) At least one of lithium manganate, lithium iron manganese phosphate, lithium titanate, and the like. In the present application, the positive electrode active material may further contain a non-metal element, for example, the non-metal element includes at least one of fluorine, phosphorus, boron, chlorine, silicon, or sulfur. In the present application, the thicknesses of the positive electrode current collector and the positive electrode material layer are not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, preferably 6 μm to 18 μm. The thickness of the single-sided positive electrode material layer is 30 μm to 120 μm. In the present application, the positive electrode material layer may further include a conductive agent and a positive electrode binder. The application has no conductive agent in the positive electrode material layerThe present application is not particularly limited as long as the object of the present application can be achieved. For example, the conductive agent may be the same as the kind of the conductive agent in the above-described anode material layer. The kind of the positive electrode binder in the positive electrode material layer is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the positive electrode binder may be the same as the type of positive electrode binder in the positive electrode material layer described above. The mass ratio of the positive electrode active material, the conductive agent and the positive electrode binder in the positive electrode material layer is not particularly limited, and can be selected by a person skilled in the art according to actual needs as long as the purpose of the present application can be achieved.
The present application is not particularly limited as long as the object of the present application can be achieved, and for example, the material of the separator may include, but is not limited to, at least one of Polyethylene (PE), polypropylene (PP) -based Polyolefin (PO), polyester (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid. The type of separator may include at least one of a woven film, a nonwoven film, a microporous film, a composite film, a rolled film, or a spun film. The separator of the present application may have a porous structure, and the size of the pore diameter of the porous structure of the separator is not particularly limited as long as the object of the present application can be achieved. For example, the pore size may be 0.01 μm to 1 μm. The thickness of the separator is not particularly limited as long as the object of the present application can be achieved, and for example, the thickness of the separator may be 4 μm to 50 μm.
The electrolyte in the electrochemical device of the present application includes a lithium salt and a nonaqueous solvent. The lithium salt may include LiPF 6 、LiNO 3 、LiBF 4 、LiClO 4 、LiB(C 6 H 5 ) 4 、LiCH 3 SO 3 、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiC(SO 2 CF 3 ) 3 、Li 2 SiF 6 At least one of lithium bis (oxalato) borate (LiBOB), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), or lithium difluoroborate. The content of the lithium salt in the electrolyte is not limited in the present application as long as the object of the present application can be achieved. The application has no non-aqueous solvent The object of the present application is particularly limited as long as it can be achieved. For example, the nonaqueous solvent may include, but is not limited to, at least one of a carbonate compound, a carboxylate compound, an ether compound, or other organic solvent. The carbonate compound may include, but is not limited to, at least one of a chain carbonate compound, a cyclic carbonate compound, or a fluorocarbonate compound. The above chain carbonate compound may include, but is not limited to, at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, or methyl ethyl carbonate. The cyclic carbonate may include, but is not limited to, at least one of ethylene carbonate, propylene Carbonate (PC), butylene carbonate, or vinyl ethylene carbonate. The fluorocarbonate compound may include, but is not limited to, at least one of fluoroethylene carbonate, 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, or trifluoromethyl ethylene carbonate. The above carboxylic acid ester compound may include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ethyl fluoroacetate, ethyl fluoroaropionate, propyl fluoroaropionate, methyl fluoroacetate, gamma-butyrolactone, decalactone, valerolactone, or caprolactone. The ether compound may include, but is not limited to, at least one of dibutyl ether, tetraglyme, diglyme, 1, 2-dimethoxyethane, 1, 2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, or tetrahydrofuran. The other organic solvents may include, but are not limited to, at least one of dimethyl sulfoxide, 1, 2-dioxolane, sulfolane, methyl sulfolane, 1, 3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate.
The secondary battery of the present application further includes a pouch for accommodating the positive electrode tab, the negative electrode tab, the separator, and the electrolyte, and other components known in the art in the secondary battery, and the present application is not limited thereto. The present application is not particularly limited, and may be any known in the art as long as the object of the present application can be achieved.
The present application is not particularly limited in the kind of secondary battery, and may include any device in which an electrochemical reaction occurs. For example, secondary batteries may include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries (lithium ion batteries), sodium ion secondary batteries (sodium ion batteries), lithium polymer secondary batteries, and lithium ion polymer secondary batteries.
The method of manufacturing the secondary battery according to the present application is not particularly limited, and a manufacturing method known in the art may be selected as long as the object of the present application can be achieved. For example, the method of manufacturing the secondary battery includes, but is not limited to, the steps of: sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate, winding and folding the positive electrode plate, the diaphragm and the negative electrode plate according to the need to obtain an electrode assembly with a winding structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag, and sealing to obtain a secondary battery; or sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate, fixing four corners of the whole lamination structure to obtain an electrode assembly of the lamination structure, placing the electrode assembly into a packaging bag, injecting electrolyte into the packaging bag, and sealing to obtain the secondary battery.
A fourth aspect of the present application provides an electronic device comprising the secondary battery according to any one of the foregoing embodiments. The secondary battery of the present application has a high energy density and a long cycle life, and therefore the electronic device of the present application has a long service life.
The electronic device of the present application is not particularly limited, and may be any electronic device known in the art. For example, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable telephone, a portable facsimile machine, a portable copier, a portable printer, a headset, a video recorder, a liquid crystal television, a hand-held cleaner, a portable CD, a mini-compact disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable audio recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flash, a camera, a household large-sized battery, and a lithium ion capacitor.
Examples
Hereinafter, embodiments of the present application will be described in more detail with reference to examples and comparative examples. The various tests and evaluations were carried out according to the following methods.
Test method and apparatus:
negative pole piece porosity test
Punching the cathode pole piece into small discs with the diameter of 14mm, preparing 30 small discs in each example or comparative example, wherein the volume of each small disc is 0.35cm 3 . And testing the porosity of the negative electrode plate according to the standard of 'GB/T24586-2009 determination of apparent density and porosity of iron ore', wherein the test gas is helium.
First efficiency test of button cell potential and pre-lithium supplementing negative electrode piece
Reference to<Preparation of negative electrode plate>Can obtain a coating weight of 7mg/cm 2 The negative electrode plate with the single-sided coating negative electrode material layer is cut into 1.54cm 2 And (2) taking a lithium sheet as a counter electrode, taking a porous polyethylene film as a diaphragm, injecting an electrolyte, wherein the electrolyte consists of 43.75% of ethylene carbonate, 43.75% of diethyl carbonate and 12.5% of lithium hexafluorophosphate based on the mass of the electrolyte, and assembling to obtain the button cell. The open circuit voltage was measured with a multimeter pair, the coin cell was discharged to 0V (vs. li+/Li) at a constant current of 0.05C, then to 0V (vs. li+/Li) at a constant current of 50 μa, and finally to 0V (vs. li+/Li) at a constant current of 20 μa, and the first discharge capacity of the coin cell was recorded. And then charging to 3.0V with a constant current of 0.1C, and recording the first charge capacity of the button cell.
First efficiency=first charge capacity/first discharge capacity x 100% of the negative electrode sheet of the pre-lithium supplement;
the first reversible gram capacity of the anode active material at 0V to 2 v=the first charge capacity of the coin cell/mass of the anode active material.
Mass percent testing of compound a
The mass percent of the compound A is measured by adopting a gas chromatography method. Firstly, scraping the negative electrode material layer from a negative electrode current collector of a negative electrode plate of the pre-lithium-supplementing negative electrode, taking 0.1g of the negative electrode material layer, dissolving the negative electrode material layer into 100mL of methanol, stirring for 5 hours at 500rpm, and filtering out insoluble substances to leave supernatant as a liquid to be tested. A standard solution of compound a was prepared and tested for its corresponding off-peak time, off-peak area and quantitative correction factor. And then testing the liquid to be tested, judging whether the liquid to be tested contains the compound A and the specific type of the compound A according to the fact that the peak time of the liquid to be tested is consistent with the peak time of the standard liquid, and calculating the content of the liquid to be tested according to the peak area and the correction factor. Wherein, the compound A is biphenyl, 2-methylbiphenyl, 3-methylbiphenyl, 4-methylbiphenyl, 3' -dimethylbiphenyl, 2-ethylbiphenyl, triethylbiphenyl, 3' -difluorobiphenyl, 4' -dimethylbiphenyl, 3', 4' -dimethylbiphenyl, 4' -methyl-3-fluorobiphenyl, naphthalene, 2-methylnaphthalene, 2'7-dimethylnaphthalene or 2-fluoronaphthalene.
Negative electrode plate thickness test of pre-lithium supplement
The thickness test is carried out on the anode pieces of the pre-lithium in the examples and the comparative examples by adopting a ten-thousandth ruler, 100 points are selected in the area of 10cm multiplied by 10cm, and the average thickness of the 100 points is the average thickness of the anode pieces of the pre-lithium.
I d /I g Testing
And cutting a cross section of the negative pole piece of the pre-lithium supplement by adopting an ion polishing method, then placing the cross section on a test bench of a Raman spectrum, and testing after focusing. The test was conducted by selecting a range of 200 μm by 500. Mu.m, within which 200 points were tested at equal intervals, each point having a test range of 1000cm -1 To 2000cm -1 The method comprises the steps of carrying out a first treatment on the surface of the At 1320cm -1 To 1370cm -1 The peak appearing in between is denoted as d peak, at 1570cm -1 To 1620cm -1 The peak appearing in the middle is marked as g peak, and the intensity ratio of d peak to g peak of each point is counted, namely the I of each point d /I g Values, and an average value was calculated as a final result.
Cycle capacity retention test
At an ambient temperature of 25 ℃, charging to 4.5V at a constant current of 0.7C, charging to 0.025C at a constant voltage of 4.5V, and discharging to 2V at 0.5C after standing for 5 minutes. And (3) taking the capacity obtained in the step as the initial capacity, performing a cyclic test according to the cyclic process, and obtaining a capacity attenuation curve by taking the capacity of each circle as a ratio to the initial capacity. After cycling to 800 circles at 25 ℃, the capacity retention rate of the lithium ion battery is obtained by using the ratio of the capacity of 800 circles to the initial capacity.
Energy density testing
In the test of the cycle capacity retention rate of the lithium ion battery, the charge-discharge curve of the first circle, the charge-discharge capacity and the energy of the lithium ion battery are recorded, the average discharge voltage of the lithium ion battery is obtained through the charge-discharge capacity/discharge capacity, and then the length, the width and the height of the lithium ion battery when the charge capacity is 50% of the remaining charge capacity are measured, so that the energy density of the lithium ion battery is obtained.
Energy density=discharge capacity×discharge average voltage/(length×width×height of lithium ion battery) of lithium ion battery.
Infrared spectroscopy testing
This test was performed with reference to the standard GB/T21186-2007 Fourier transform Infrared spectrometer. The test light source is a middle infrared Ever-Glo light source, the beam splitter is KBr/Ge, and the interferometer is a Michelson interferometer; the test is carried out by taking 4cm multiplied by 4cm of the negative pole piece, and the test range is 4000cm -1 To 400cm -1 Between these, the test was repeated twice.
Example 1-1
< preparation of negative electrode sheet >
The preparation method comprises the steps of mixing hard carbon, sodium carboxymethylcellulose (CMC-Na) and Styrene Butadiene Rubber (SBR) serving as anode active materials according to a mass ratio of 97:2:1, adding deionized water serving as a solvent, and stirring and mixing uniformly to obtain anode slurry with a solid content of 40 wt%. And uniformly coating the negative electrode slurry on one surface of a negative electrode current collector copper foil with the thickness of 6 mu m, and drying at the temperature of 85 ℃ to obtain a negative electrode plate with the coating thickness of 60 mu m and a single-sided coating negative electrode material layer. And repeating the steps on the other surface of the negative current collector copper foil to obtain the negative electrode plate with the double-sided coating negative electrode material layer.
< preparation of lithium-supplementing solution >
In an operation room with an exhaust system in a drying room environment, adding a compound A (biphenyl) and a lithium sheet into an ethylene glycol dimethyl ether (DME) solution, wherein the adding proportion is shown in table 2, stirring the solution, filtering undissolved metallic lithium after the solution, and obtaining a lithium supplementing solution, wherein the mass percentage of the pre-lithium supplementing compound is 9.5% and the mass percentage of the compound A is 8.0% based on the mass of the lithium supplementing solution.
< preparation of negative electrode sheet for lithium Premake-up >
As shown in fig. 1, the negative electrode piece obtained in the preparation of the negative electrode piece is put on an unreeling device 01, is transported along the direction of transport direction W, is subjected to first cold pressing treatment at a first cold pressing device 02, the pressure of the first cold pressing treatment is 0.05 ton, then the negative electrode piece after the first cold pressing treatment is immersed in a lithium supplementing solution of a lithium supplementing reagent pool 03 for carrying out pre-lithium supplementing treatment, the immersion time is 5min, after the immersion is finished, the negative electrode piece after the pre-lithium supplementing treatment is transported to a cleaning pool 04 for cleaning for 10min, then is dried at a drying device 05, the dried negative electrode piece is subjected to second cold pressing treatment at a second cold pressing device 06, the pressure of the second cold pressing treatment is 3 ton, and a winding device 07 recovers the negative electrode piece after the second cold pressing treatment to obtain the negative electrode piece after the pre-lithium supplementing. And after cutting and slitting, drying for 4 hours under the vacuum condition of 85 ℃ to obtain the anode piece with the specification of 91.2mm multiplied by 485mm after lithium pre-supplementing. Wherein the thickness of the single-sided negative electrode material layer is 63 mu m, and the cleaning agent in the cleaning tank is DME.
< preparation of Positive electrode sheet >
Lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) The conductive agent Super P and the binder polyvinylidene fluoride (PVDF) are dispersed in N-methylpyrrolidone (NMP) solution according to the mass ratio of 97:1.4:1.6The mixture was stirred and mixed sufficiently to obtain a positive electrode slurry having a solid content of 72 wt%. And uniformly coating the positive electrode slurry on one surface of a positive electrode current collector aluminum foil with the thickness of 8 mu m, and drying at the temperature of 85 ℃ to obtain the positive electrode plate with the coating thickness of 57 mu m and the single-sided coating positive electrode material layer. And repeating the steps on the other surface of the positive current collector aluminum foil to obtain the positive electrode plate with the double-sided coating positive electrode material layer. And then cold pressing, cutting and slitting, and drying for 4 hours under the vacuum condition of 85 ℃ to obtain the positive pole piece with the specification of 90mm multiplied by 480mm for standby.
< preparation of separator >
A Polyethylene (PE) porous polymer film having a thickness of 7 μm was used as the separator.
< preparation of electrolyte >
In a dry argon atmosphere glove box, organic solvents of Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a mass ratio of 30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent 6 ) And (5) fully and uniformly mixing to obtain the electrolyte. LiPF based on electrolyte mass 6 The mass percentage of (2) is 12.5%.
< preparation of lithium ion Battery >
And sequentially stacking the prepared positive electrode plate, the diaphragm and the negative electrode plate of the pre-lithium-ion battery in sequence to ensure that the diaphragm is positioned between the positive electrode and the negative electrode to play a role of isolation, then winding, welding the electrode lugs, placing the electrode lugs in an outer packaging foil aluminum plastic film, injecting electrolyte, and carrying out the procedures of vacuum packaging, standing, formation, shaping, capacity testing and the like to obtain the soft-package lithium ion battery.
Examples 1-2 to 1-4
The procedure of example 1-1 was repeated except that the relevant preparation parameters were adjusted in accordance with tables 1 and 2.
Examples 1 to 5
The procedure was as in examples 1-4, except that < preparation of lithium-compensating solution > was as follows, and the relevant preparation parameters were adjusted as in tables 1 and 2.
< preparation of lithium-supplementing solution >
In an operation room with an exhaust system in a drying room environment, adding a compound A (2-methyl biphenyl), a lithium sheet and polyvinylidene fluoride (PVDF) into an ethylene glycol dimethyl ether (DME) solution according to the adding proportion shown in Table 2, stirring to dissolve each other, and filtering undissolved metallic lithium to obtain a lithium supplementing solution with the mass percent of the pre-supplementing lithium compound of 10.5%, wherein the mass percent of the compound A is 8.7%, and the mass percent of the PVDF is 0.3%.
Examples 1 to 6 to 1 to 9
The procedure of example 1-1 was repeated except that the relevant preparation parameters were adjusted in accordance with tables 1 and 2.
Examples 1 to 10
The procedure is as in examples 1-5, except that the relevant preparation parameters are adjusted according to tables 1 and 2.
Examples 1 to 11 to 1 to 14
The procedure of example 1-1 was repeated except that the relevant preparation parameters were adjusted in accordance with tables 1 and 2.
Examples 1 to 15
The procedure is as in examples 1-5, except that the relevant preparation parameters are adjusted according to tables 1 and 2.
Examples 1 to 16 to 1 to 19
The procedure of example 1-1 was repeated except that the relevant preparation parameters were adjusted in accordance with tables 1 and 2.
Examples 1 to 20 to 1 to 22
The procedure is as in examples 1-5, except that the relevant preparation parameters are adjusted according to tables 1 and 2.
Examples 1 to 23
The procedure of examples 1-20 was repeated except that the fluoride polyvinylidene fluoride (PVDF) in < preparation of lithium-compensating solution > was replaced with sodium fluoride (NaF), and the amount of sodium fluoride added was adjusted.
Examples 1 to 24 to 1 to 25
The procedure of example 1-1 was repeated except that the relevant preparation parameters were adjusted in accordance with tables 1 and 2.
Examples 2-1 to 2-4
The procedure of example 1-1 was repeated except that the relevant production parameters were adjusted as shown in Table 3.
Examples 3-1 to 3-5
The procedure of example 1-1 was repeated except that the relevant production parameters were adjusted as shown in Table 4.
Comparative examples 1 to 1
The negative electrode sheet in comparative example 1-1 was not subjected to the pre-lithium treatment process and the washing process in the < preparation of a negative electrode sheet for pre-lithium > process, and the rest was exactly the same as example 1-1 except that the relevant preparation parameters were adjusted according to tables 1 and 2.
Comparative examples 1-2 to 1-4
The procedure was as in comparative example 1-1, except that the relevant preparation parameters were adjusted according to tables 1 and 2.
The preparation parameters and performance parameters of each example and comparative example are shown in tables 1 to 4.
TABLE 1
/>
Note that: the "/" in Table 1 indicates no relevant preparation parameters. The 10% silicon carbon+90% graphite in examples 1 to 11 means that the mass percentage of the silicon carbon material is 10% and the mass percentage of the graphite material is 90% based on the mass of the anode active material. Other examples and comparative examples are understood by analogy.
TABLE 2
/>
Note that: the "/" in Table 2 indicates no relevant preparation parameters.
As can be seen from examples 1-1 to 1-25 and comparative examples 1-1 to 1-4, the potential of the secondary battery composed of the negative electrode tab of the pre-charged lithium and metallic lithium as the counter electrode in the examples of the present application is not more than 1V, the first efficiency of the negative electrode tab of the pre-charged lithium is higher, the energy density of the lithium ion battery is higher, the cycle capacity retention rate is higher, indicating that the lithium ion battery in the examples of the present application has higher energy density and longer cycle life. As can be seen from fig. 2, after lithium is supplemented in the lithium ion battery of example 1-1 by the preparation method of the present application, the discharge potential of example 1-1 is significantly reduced compared with that of comparative example 1-1, and the first efficiency of example 1-1 is higher at the same gram capacity, so that the energy density is higher. From fig. 3, the micro-morphology of the negative electrode sheet in example 1-1 after the lithium pre-supplementation can be seen. As can be seen from FIG. 4, example 1-1 was carried out at 1350cm as compared with comparative example 1-1 -1 To 1450cm -1 There is a characteristic peak in between. As can be seen from comparative examples 1-1 to 1-4, the potential of the secondary battery composed of the negative electrode tab of the pre-lithium and the metallic lithium as the counter electrode in comparative examples 1-1 to 1-4 is all greater than 1V, the first efficiency of the negative electrode tab of the pre-lithium is lower, the energy density of the lithium ion battery is lower, the cycle capacity retention rate is lower, indicating that the lithium ion battery in comparative example has lower energy density and shorter cycle life.
The type and amount of compound a generally affects the energy density and cycle performance of lithium ion batteries. From examples 1-1 to 1-4 and examples 1-24 to 1-25, examples 1-6 to 1-9, examples 1-11 to 1-14, and examples 1-16 to 1-19, it can be seen that when the kind and content of the compound a, the content of the pre-lithium compound are within the scope of the present application, the first efficiency of the negative electrode tab of the pre-lithium is higher, the energy density of the lithium ion battery is higher, and the cycle capacity retention rate is higher, indicating that the lithium ion battery in the examples of the present application has a higher energy density and a longer cycle life.
The kind of the negative electrode active material generally affects the energy density and cycle performance of the lithium ion battery. It can be seen from examples 1-1, examples 1-6, examples 1-11 and examples 1-16 that when the kind of the negative electrode active material is within the scope of the present application, the first efficiency of the negative electrode tab of the pre-lithium is higher, the energy density of the lithium ion battery is higher, the cycle capacity retention rate is higher, and it is illustrated that the lithium ion battery in the examples of the present application has higher energy density and longer cycle life.
The type and mass percent of fluoride in the lithium-compensating solution can affect the energy density and cycle performance of the lithium ion battery. It can be seen from examples 1-20 to examples 1-23 that when the types and mass percentages of the fluoride in the lithium supplementing solution are within the scope of the present application, the first efficiency of the negative electrode tab of the pre-lithium supplementing is higher, the energy density of the lithium ion battery is higher, the cycle capacity retention rate is higher, and it is demonstrated that the lithium ion battery in the examples of the present application has a higher energy density and a longer cycle life.
TABLE 3 Table 3
As can be seen from examples 1-1, 2-1 to 2-4, when the mass percentage of the compound a in the negative electrode material layer is within the scope of the present application, the first efficiency of the negative electrode tab of the pre-lithium-supplementing is higher, the energy density of the lithium ion battery is higher, and the cycle capacity retention rate is higher, which indicates that the lithium ion battery in the examples of the present application has higher energy density and longer cycle life.
TABLE 4 Table 4
Note that: the "/" in Table 4 indicates no relevant preparation parameters.
Porosity ρ of the negative electrode sheet after the first cold press treatment 1 And porosity ρ of the negative electrode sheet after the second cold press treatment 2 Which typically affects lithium ion batteriesEnergy density and cycle performance. It can be seen from examples 1-1, 3-1 to 3-5 that the porosity ρ of the negative electrode sheet after the first cold press treatment 1 And porosity ρ of the negative electrode sheet after the second cold press treatment 2 In the range of the application, the first efficiency of the negative electrode plate of the pre-lithium supplement is higher, the energy density of the lithium ion battery is higher, and the cycle capacity retention rate is higher, which indicates that the lithium ion battery in the embodiment of the application has higher energy density and longer cycle life.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, or article that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, or article.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments.
The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.
Claims (10)
1. The negative electrode plate of the pre-lithium supplement comprises a negative electrode current collector and a negative electrode material layer positioned on at least one surface of the negative electrode current collector, wherein metal lithium is used as a counter electrode to form a secondary battery with the negative electrode plate of the pre-lithium supplement, and the potential of the secondary battery is 0.2V to 1V.
2. The negative electrode tab of claim 1, wherein the secondary battery has a potential of 0.29V to 0.8V.
3. The pre-lithium-compensating negative electrode tab of claim 1, wherein the negative electrode material layer comprises a compound a comprising at least one of a compound of formula (I) or formula (II);
wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 An alkyl group or a fluorine atom; the C is 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms;
the mass percentage content of the compound a is 0.01% to 0.1% based on the mass of the anode material layer.
4. The pre-lithium negative electrode tab of claim 1, wherein the negative electrode material layer comprises a negative electrode active material comprising at least one of hard carbon, graphite, a silicon oxygen material, or a silicon carbon material.
5. The pre-lithium negative electrode tab of claim 1, wherein at least one of the following characteristics is satisfied:
(1) The thickness of the negative electrode material layer is 30-100 [ mu ] m;
(2) The porosity of the negative electrode material layer is 20% to 45%;
(3) In the infrared spectrogram spectrum, the negative pole piece of the pre-lithium supplement is 1350cm -1 To 1450cm -1 There is a characteristic peak in between.
6. A method of preparing the negative electrode tab of pre-lithium of any one of claims 1 to 5, comprising the steps of: carrying out primary cold pressing treatment on the negative electrode piece, immersing the negative electrode piece subjected to primary cold pressing treatment in a lithium supplementing solution for carrying out pre-lithium supplementing treatment, cleaning and drying the negative electrode piece subjected to the pre-lithium supplementing treatment, and carrying out secondary cold pressing treatment on the dried negative electrode piece to obtain the negative electrode piece subjected to the pre-lithium supplementing treatment;
wherein the pressure of the first cold pressing treatment is 0.01 ton to 1 ton, and the pressure of the second cold pressing treatment is 1 ton to 30 tons;
The lithium supplementing solution comprises a pre-lithium supplementing compound, the pre-lithium supplementing compound comprises a lithium source and a compound A,
the compound A comprises at least one of compounds shown in a formula (I) or a formula (II);
wherein X is 1 To X 10 、Y 1 To Y 8 Each independently selected from hydrogen atom, substituted or unsubstituted C 1 To C 6 An alkyl group or a fluorine atom; the C is 1 To C 6 When the alkyl group of (2) is substituted, the substituent is selected from fluorine atoms;
the mass percentage of the pre-lithium supplementing compound is 5 to 30 percent based on the mass of the lithium supplementing solution.
7. The preparation method of claim 6, wherein the lithium supplementing solution further comprises fluoride including at least one of polyvinylidene fluoride, lithium fluoride, sodium fluoride, potassium fluoride, or antimony trifluoride, and the mass percentage of fluoride is 0.1% to 20% based on the mass of the lithium supplementing solution.
8. The production method according to claim 6, wherein the porosity ρ of the negative electrode sheet after the first cold press treatment 1 30 to 60 percent of the porosity rho of the anode piece of the pre-lithium supplement after the second cold pressing treatment 2 10 to 50 percent, 5 percent or less rho 1 -ρ 2 ≤30％。
9. A secondary battery comprising a positive electrode sheet, a separator, and the negative electrode sheet of pre-lithium according to any one of claims 1 to 5 or the negative electrode sheet of pre-lithium produced according to the production method of any one of claims 6 to 8.
10. An electronic device comprising the secondary battery according to claim 9.
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