CN116565293A - Electrochemical device and electronic device - Google Patents

Electrochemical device and electronic device Download PDF

Info

Publication number
CN116565293A
CN116565293A CN202310827506.9A CN202310827506A CN116565293A CN 116565293 A CN116565293 A CN 116565293A CN 202310827506 A CN202310827506 A CN 202310827506A CN 116565293 A CN116565293 A CN 116565293A
Authority
CN
China
Prior art keywords
lithium
positive electrode
electrolyte
electrochemical device
negative electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310827506.9A
Other languages
Chinese (zh)
Inventor
林小萍
谢远森
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Priority to CN202310827506.9A priority Critical patent/CN116565293A/en
Publication of CN116565293A publication Critical patent/CN116565293A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive pole piece, a negative pole piece, electrolyte and a diaphragm; the positive electrode plate comprises a positive electrode active material, wherein the positive electrode active material contains M element, and the M element comprises at least one of Mn, ni, co or Fe; the negative electrode plate comprises M elements, and the mass percentage content X% of the M elements is 0.05-1% based on the mass of the negative electrode plate; the electrolyte comprises fluorine-containing lithium salt, and the mass percentage C% of the fluorine-containing lithium salt is 5-65% based on the mass of the electrolyte. The negative electrode plate comprises M element, X% is regulated and controlled within the application range, the electrolyte comprises fluorine-containing lithium salt, C% is regulated and controlled within the application range, and the accumulation amount of byproducts on the surface of the negative electrode plate can be reduced, so that the impedance of the electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance of the electrochemical device is improved.

Description

Electrochemical device and electronic device
Technical Field
The present disclosure relates to the field of electrochemical technologies, and in particular, to an electrochemical device and an electronic device.
Background
Electrochemical devices, such as lithium metal batteries, have the advantages of high energy density, high operating voltage, low self-discharge rate, small volume, light weight, and the like, and have wide application in the consumer electronics field. The lithium metal has high theoretical specific capacity and wide application prospect in lithium metal batteries. Therefore, the energy density and the operating voltage of the lithium metal battery can be greatly improved by using lithium metal as the negative electrode and simultaneously using the positive electrode comprising the high-energy-density positive electrode material.
However, due to the extremely high activity of lithium metal, byproducts of the lithium metal reaction with the electrolyte can be accumulated on the negative electrode plate continuously, so that the impedance of the lithium metal battery is increased continuously in the circulation process, and the accumulated byproducts can influence the transmission of lithium ions, thereby influencing the circulation performance of the electrochemical device.
Disclosure of Invention
The present application is directed to an electrochemical device and an electronic device for improving cycle performance of the electrochemical device. The specific technical scheme is as follows:
a first aspect of the present application provides an electrochemical device comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator; the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material. The positive electrode active material contains an M element including at least one of Mn, ni, co, or Fe. The negative electrode plate comprises M elements, and the mass percentage content X% of the M elements is 0.05-1% based on the mass of the negative electrode plate. The electrolyte comprises fluorine-containing lithium salt, and the mass percentage C% of the fluorine-containing lithium salt is 5-65% based on the mass of the electrolyte. The electrochemical device comprises an anode active material containing M element, wherein the M element in the anode active material is dissolved out in a positive ion form in a circulating process, and passes through electrolyte to migrate to a cathode plate under the drive of an electric field, and is reduced to metal M on the surface of the cathode plate, and the metal M can catalyze the decomposition of a solid electrolyte interface film and byproducts. The method can promote the dissolution, migration and deposition processes of M element by controlling the mass percentage content C% of the fluorine-containing lithium salt within the scope of the application. The positive electrode active material comprises an M element, the negative electrode plate comprises an M element, the value of X is regulated and controlled within the application range, the electrolyte comprises fluorine-containing lithium salt, the value of C is regulated and controlled within the application range, and the byproduct accumulation amount on the surface of the negative electrode plate can be reduced, so that the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance and the expansion performance of the electrochemical device are improved.
In some embodiments of the present application, the electrolyte further comprises lithium nitrate, the mass percent content d% of lithium nitrate being 0.1% to 10% based on the mass of the electrolyte; X/D satisfies: X/D is more than or equal to 0.01 and less than or equal to 3. The electrolyte comprises lithium nitrate, and the D% and X/D values are regulated and controlled within the above ranges, so that inorganic components such as lithium nitride and the like are included in the solid electrolyte interface film on the surface of the negative electrode plate, and the uniformity of lithium metal deposition can be improved, thereby improving the cycle performance and the expansion performance of the electrochemical device.
In some embodiments of the present application, the electrolyte further comprises fluoroethylene carbonate, the mass percent e% of the fluoroethylene carbonate is 1% to 20%, X/E is satisfied, based on the mass of the electrolyte; X/E is more than or equal to 0.0025 and less than or equal to 1. The electrolyte comprises fluoroethylene carbonate, and the values of E% and X/E are regulated and controlled within the range, so that the content of inorganic lithium salt lithium fluoride in the solid electrolyte interface film on the surface of the negative electrode plate can be increased, the uniformity of lithium metal deposition is improved, and the cycle performance and the expansion performance of an electrochemical device are improved.
In some embodiments of the present application, the fluorine-containing lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium difluorooxalato borate, lithium hexafluoroborate, or lithium hexafluoroarsenate. The fluorine-containing lithium salt in the above range is selected to enhance the ion transport rate in the electrolyte, the deintercalation rate of lithium ions in the positive electrode active material, and the deposition uniformity of lithium metal on the surface of the negative electrode sheet, thereby improving the cycle performance and expansion performance of the electrochemical device, and also improving the kinetic performance of the electrochemical device, such as coulombic efficiency.
In some embodiments of the present application, the mass percentage content X% of the M element is 0.1% to 0.5% based on the mass of the negative electrode tab. The mass percentage content X% of the M element is regulated within the range, so that the solid electrolyte interface film and the byproduct decomposition on the surface of the negative electrode plate are facilitated to be catalyzed, the byproduct accumulation amount on the surface of the negative electrode plate can be reduced, the impedance of the electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance and the expansion performance of the electrochemical device are improved.
In some embodiments of the present application, X/C satisfies: X/C is more than or equal to 0.0007 and less than or equal to 0.2. The method is favorable for promoting the dissolution and migration of M element, catalyzing the decomposition of the solid electrolyte interface film and byproducts on the surface of the negative electrode plate, reducing the accumulation of the byproducts on the surface of the negative electrode plate, and improving the cycle performance and the expansion performance of the electrochemical device.
In some embodiments of the present application, the positive electrode active material includes at least one of lithium manganate, lithium nickel cobalt manganate, lithium rich manganese, lithium cobaltate, lithium nickelate, lithium iron phosphate, or manganese carbonate doped lithium iron phosphate. The substance is selected as an anode active material, M element can be dissolved out in a positive ion form in a circulating process, the M element is reduced to metal M on the surface of the anode plate, the solid electrolyte interface film and byproducts are catalyzed to decompose, and the accumulation amount of the byproducts on the surface of the anode plate can be reduced, so that the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the circulating performance and the expansion performance of the electrochemical device are improved.
In some embodiments of the present application, the current collector includes any one of copper foil, titanium foil, stainless steel, carbon paper, and graphene paper. The current collector in the range is selected, lithium ions separated from the positive electrode active material migrate to the negative electrode in the first charging process, a lithium metal layer is formed on the current collector in a deposition mode, M elements migrating to the negative electrode are reduced to metal M by lithium metal on the surface of the negative electrode plate, the solid electrolyte interface film and byproducts are catalyzed to decompose, and the accumulation amount of byproducts on the surface of the negative electrode plate can be reduced, so that the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance and the expansion performance of the electrochemical device are improved.
In some embodiments of the present application, the electrochemical device meets at least one of the following features: (1) the mass percent C% of the fluorine-containing lithium salt is 20-56%; (2) The electrolyte comprises lithium nitrate, and the mass percentage content D% of the lithium nitrate is 0.5-5% based on the mass of the electrolyte; (3) 0.0007.ltoreq.X/C.ltoreq.0.1. The electrochemical device satisfying the above characteristics has good cycle performance and expansion performance.
A second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application. The electrochemical device provided in the first aspect of the present application has good cycle performance and expansion performance, so that the electronic device provided in the second aspect of the present application has a long service life.
The beneficial effects of this application:
the application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive pole piece, a negative pole piece, electrolyte and a diaphragm; the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material containing an M element including at least one of Mn, ni, co, or Fe. The negative electrode plate comprises M elements, and the mass percentage content X% of the M elements is 0.05-1% based on the mass of the negative electrode plate. The electrolyte comprises fluorine-containing lithium salt, and the mass percentage C% of the fluorine-containing lithium salt is 5-65% based on the mass of the electrolyte. The electrochemical device comprises a positive electrode active material containing M element, wherein the M element in the positive electrode active material is dissolved out in a positive ion form in a circulating process, and passes through electrolyte to migrate to a negative electrode plate, and is reduced to metal M on the surface of the negative electrode plate, and the metal M can catalyze the decomposition of a solid electrolyte interface film and byproducts. The method can promote the dissolution, migration and deposition processes of M element by controlling the mass percentage content C% of the fluorine-containing lithium salt within the scope of the application. The positive electrode active material comprises an M element, the negative electrode plate comprises an M element, the value of X is regulated and controlled within the application range, the electrolyte comprises fluorine-containing lithium salt, the value of C is regulated and controlled within the application range, the accumulation amount of byproducts on the surface of the negative electrode plate can be reduced, the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance and the expansion performance of the electrochemical device are improved.
Of course, it is not necessary for any one product or method of practicing the invention to achieve all of the advantages set forth above at the same time.
Drawings
In order to more clearly illustrate the embodiments of the invention 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 invention, and other embodiments may be obtained according to these drawings to those skilled in the art.
Fig. 1 is a schematic structural view of an electrochemical device in one embodiment of the present application;
FIG. 2 is a Scanning Electron Microscope (SEM) photograph of a cross section of a negative electrode tab of the lithium metal battery of comparative example 1 in the thickness direction after cycling;
FIG. 3 is an SEM photograph of a cross section of a negative electrode tab of the lithium metal battery of example 1-1 in the thickness direction after cycling;
fig. 4 is a graph showing the capacity retention rate versus the number of cycles of the lithium metal batteries prepared in example 1-1 and comparative example 1.
Reference numerals: electrochemical device 100, positive electrode sheet 10, negative electrode sheet 20, separator 30, positive electrode current collector 11, and positive electrode active material layer 12.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments obtained based on the present application by a person skilled in the art are within the scope of the protection of the present application.
In the specific embodiment of the present application, the present application is explained using a lithium metal battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to the lithium metal battery.
At present, it is generally required to suppress elution of metal elements, particularly elution of transition metal elements such as manganese, nickel, cobalt, and iron in lithium ion batteries. Because the dissolution of metal elements or the side reaction in the lithium ion battery is increased, and part of metal dissolution is irreversible after participating in the side reaction, the cycle performance, the capacity and the like of the lithium ion battery are affected. Meanwhile, in the existing lithium metal battery, due to the high activity of lithium metal, the lithium metal reacts with electrolyte to cause continuous accumulation of byproducts, impedance is continuously increased in a circulating process, and the accumulated byproducts and a solid electrolyte interface film are not beneficial to the transmission of lithium ions, so that the circulating performance of an electrochemical device is reduced. Based on the above-described problems, the present application provides an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device.
In view of this, a first aspect of the present application provides an electrochemical device comprising a positive electrode tab, a negative electrode tab, an electrolyte, and a separator; the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector. In the present application, the positive electrode active material layer may be provided on one surface in the thickness direction of the positive electrode current collector, or may be provided on both surfaces in the thickness direction of the positive electrode current collector. Illustratively, as shown in fig. 1, an electrochemical device 100 includes a positive electrode tab 10, a negative electrode tab 20, an electrolyte (not shown in fig. 1), and a separator 30; the positive electrode tab 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one surface of the positive electrode current collector 11. The positive electrode active material layer includes a positive electrode active material containing an M element including at least one of Mn, ni, co, or Fe. The negative electrode sheet comprises M element, wherein the mass percentage content of the M element is 0.05 to 1 percent, preferably 0.1 to 0.5 percent; for example, the value of X may be 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1 or a range of any two values therein. The electrolyte comprises a fluorine-containing lithium salt, wherein the mass percent of the fluorine-containing lithium salt is 5-65%, preferably 20-56% based on the mass of the electrolyte; for example, the value of C may be 5, 10, 15, 20, 25, 30, 40, 50, 60, 65 or a range of any two values therein.
When the value of X is too small, the metal M on the surface of the negative electrode plate is too small, the decomposition speed of the catalytic solid electrolyte interface film and byproducts is too slow, and the byproducts are continuously accumulated, so that the thickness of the byproducts on the surface of the negative electrode plate is larger, and the cycle performance of the lithium metal battery is not improved. When the value of X is too large, M element in the positive electrode active material is dissolved out too much, the structure of the positive electrode active material is damaged, the capacity of the electrochemical device is rapidly attenuated and even the safety problem is caused, and excessive lithium metal is consumed due to the excessive M element dissolution, so that the cycle performance of the lithium metal battery is not improved. When the value of C is too small, on one hand, the basic solvent in the electrolyte reacts with lithium metal vigorously to generate a large amount of byproducts which are accumulated on the surface of the negative electrode plate, so that the coulomb efficiency and the cycle performance of the lithium metal battery are not improved; on the other hand, dissolution of M element in the positive electrode active material is accelerated, and the structure of the positive electrode active material is damaged, resulting in rapid capacity decay of the electrochemical device, which is unfavorable for improving the cycle performance of the electrochemical device. When the value of C is too large, the viscosity of the electrolyte is too high to influence the migration of ions in the electrolyte, so that the dissolution and migration of M element in the positive electrode active material are not facilitated, the byproducts on the surface of the negative electrode plate are continuously accumulated, the transmission of lithium ions is blocked, and the cycle performance of an electrochemical device is not facilitated to be improved. In the electrochemical device, the positive electrode active material comprises M element, the negative electrode plate comprises M element which migrates to the negative electrode plate in the circulation, the electrolyte comprises fluorine-containing lithium salt and regulates and controls the value of X and the value of C to be within the range of the application, so that part of M element in the positive electrode active material is dissolved into the electrolyte in the circulation process of the electrochemical device, under the driving of an electric field, the M element migrates from the positive electrode plate to the surface of the negative electrode plate, cations of the M element can be reduced to metal M on the surface of the negative electrode plate, and the metal M can catalyze and decompose part of solid electrolyte interface film and byproducts (such as Li 2 CO 3 And the like), the accumulation amount of byproducts on the surface of the negative electrode plate is reduced, so that an ion transmission channel is smooth, and the cycle performance of the electrochemical device is improved. From these results, it is found that the electrochemical device provided in the present application needs to dissolve part of M element and migrate positive electrode active material to negative electrode by utilizing high activity of lithium metal in lithium metal batteryThe M element on the surface of the pole piece is reduced, and the decomposition of the SEI film and accumulated byproducts is catalyzed in the circulation process, so that an ion transmission channel is smooth, which is completely opposite to the situation that the dissolution of the M element is usually required to be restrained in the lithium ion battery in the prior art so as to improve the performance of the lithium ion battery, namely, the technical bias is overcome, the circulation performance of an electrochemical device can be improved, and the beneficial technical effect is realized.
In some embodiments of the present application, the negative electrode tab is lithium metal. The M element in the positive electrode active material is dissolved into electrolyte in the circulation process, and is driven by an electric field to migrate to the surface of the negative electrode plate, and is reduced into metal M by lithium metal on the surface of the negative electrode plate, and the metal M can catalyze and decompose an SEI film, so that an ion transmission channel is smooth, and the circulation performance of the electrochemical device is improved.
In other embodiments of the present application, the negative electrode tab is a current collector comprising any one of copper foil, titanium foil, stainless steel, carbon paper, and graphene paper. And in the first charging process, lithium ions separated from the positive electrode active material migrate to the negative electrode, the lithium ions can deposit on the current collector to form a lithium metal layer, M element is reduced to metal M by lithium metal on the surface of the negative electrode sheet, the solid electrolyte interface film and byproducts are catalyzed to decompose, and the reduction of the accumulation amount of the byproducts on the surface of the negative electrode sheet is facilitated, so that the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the cycle performance and the expansion performance of the electrochemical device are improved.
In some embodiments of the present application, the electrolyte further comprises lithium nitrate, the mass percent content d% of lithium nitrate being 0.1% to 10%, preferably 0.5% to 5%, based on the mass of the electrolyte; X/D satisfies: X/D is more than or equal to 0.01 and less than or equal to 3. For example, the value of D may be 0.1, 0.5, 1, 2, 2.5, 3, 4, 5, 6, 8, 10 or a range of any two values therein; the value of X/D may be 0.01, 0.02, 0.05, 0.07, 0.1, 0.2, 0.5, 1, 1.2, 1.5, 2, 2.5, 3 or a range of any two values therein. The electrolyte comprises lithium nitrate, and the D% and X/D values are regulated and controlled within the above ranges, so that inorganic components such as lithium nitride and the like are included in the solid electrolyte interface film on the surface of the negative electrode plate, and the uniformity of lithium metal deposition can be improved, thereby being beneficial to improving the cycle performance and expansion performance of an electrochemical device.
In some embodiments of the present application, the electrolyte further comprises fluoroethylene carbonate, the mass percent e% of the fluoroethylene carbonate is 1% to 20%, X/E is satisfied, based on the mass of the electrolyte; X/E is more than or equal to 0.0025 and less than or equal to 1. For example, the value of E may be 1, 2, 3, 4, 5, 6, 8, 10, 13, 15, 16, 18, 20 or a range of any two values therein; the value of X/E may be 0.0025, 0.005, 0.01, 0.015, 0.02, 0.05, 0.07, 0.1, 0.2, 0.5, 1 or a range of any two values therein. The electrolyte comprises fluoroethylene carbonate, and the values of E% and X/E are regulated and controlled within the range, so that the content of inorganic components such as lithium fluoride in the solid electrolyte interface film on the surface of the negative electrode plate can be increased, the uniformity of lithium metal deposition is improved, and the cycle performance and the expansion performance of an electrochemical device are improved.
In some embodiments of the present application, the fluorine-containing lithium salt comprises lithium hexafluorophosphate (LiPF 6 ) Lithium bis (fluorosulfonyl) imide (LiLSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium difluorooxalato borate (LiDFOB), lithium hexafluoroborate (LiBF) 6 ) Or lithium hexafluoroarsenate (LiAsF) 6 ) At least one of them. The fluorine-containing lithium salt in the above range is selected to enhance the rate of lithium ion transfer in the electrolyte, the rate of lithium ion deintercalation in the positive electrode active material, and the uniformity of deposition of lithium metal on the surface of the negative electrode sheet, thereby improving the cycle performance and expansion performance of the electrochemical device, and also improving the kinetic performance of the electrochemical device, such as coulombic efficiency.
In some embodiments of the present application, X/C satisfies: X/C is more than or equal to 0.0007 and less than or equal to 0.2, preferably more than or equal to 0.0007 and less than or equal to 0.1. For example, the value of X/C may be 0.0007, 0.0015, 0.0025, 0.003, 0.005, 0.006, 0.008, 0.01, 0.015, 0.02, 0.05, 0.07, 0.1, 0.15, 0.2, or a range of values consisting of any two of these. The X/C value is regulated to meet the above range, so that the dissolution and migration of M element are promoted, the solid electrolyte interface film and byproducts on the surface of the negative electrode plate are catalyzed to decompose, the accumulation amount of the byproducts on the surface of the negative electrode plate is reduced, and the cycle performance and expansion performance of the electrochemical device are improved.
In some embodiments of the present application, the positive electrode active material includes lithium manganate (LiMn 2 O 4 ) Lithium nickel cobalt manganese oxide (NCM), lithium-rich manganese (gamma Li) 2 MnO 3 ·(1-γ)LiYO 2 ，0<γ<1, Y is a transition metal), lithium cobaltate (LiCoO) 2 ) Lithium nickelate (LiNiO) 2 ) Lithium iron phosphate (LiFePO) 4 ) Or manganese carbonate doped lithium iron phosphate (MnCO) 3 Doped LiFePO 4 ) Wherein the NCM comprises LiNi 0.8 Co 0.1 Mn 0.1 O 2 （NCM811）、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 613) or LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523). The substance is selected as an anode active material, M element can be dissolved out in a positive ion form in a circulating process, and under the drive of an electric field, the positive ion passes through electrolyte and a diaphragm to migrate to a negative electrode plate, is reduced to metal M on the surface of the negative electrode plate, catalyzes the decomposition of a solid electrolyte interface film and byproducts, and is beneficial to reducing the accumulation amount of the byproducts on the surface of the negative electrode plate, so that the impedance of an electrochemical device is reduced, the smoothness of an ion transmission channel is facilitated, and the circulating performance and the expansion performance of the electrochemical device are improved.
The content of the positive electrode active material is not particularly limited in the present application as long as the object of the present application can be achieved. For example, the mass percentage of the positive electrode active material is 75% to 99% based on the mass of the positive electrode active material layer. In the present application, when the positive electrode active material includes two or more of the above materials, the mixing ratio thereof is not particularly limited, and may be used in any ratio as long as the object of the present application can be achieved. In some embodiments, the positive electrode active material includes manganese carbonate doped lithium iron phosphate, and the doping amount of manganese carbonate is not particularly limited as long as the object of the present application can be achieved. For example, manganese carbonate may be doped in an amount of 0.1% to 10%. The manganese carbonate doped lithium iron phosphate can be obtained by mixing manganese carbonate and lithium iron phosphate.
In general, the mass percentage content X% of the M element can be adjusted by changing the kind of the positive electrode active material. The positive electrode active material with high dissolution rate of the M element is selected, so that the mass percentage content X% of the M element can be increased; the positive electrode active material with low dissolution rate of the M element is selected, so that the mass percentage content X% of the M element can be reduced. The value of X can also be regulated by using two or more materials with different dissolution rates in combination. Alternatively, the mass percentage content X% of the M element may be adjusted by changing the mass percentage content of the positive electrode active material. The mass percentage content of the positive electrode active material is increased, and the mass percentage content X% of M element can be increased; the mass percentage of the positive electrode active material is reduced, and the mass percentage of M element can be reduced by X%. Or, the mass percentage content X of the M element can be adjusted by adjusting the particle size Dv50 of the positive electrode active material, coating and doping the positive electrode active material and the like, and can be adjusted according to actual needs, and the application is not repeated one by one. The method of adjusting the particle diameter Dv50 of the positive electrode active material is not particularly limited as long as the object of the present application can be achieved. For example, the particle diameter Dv50 of the positive electrode active material may be adjusted by grinding, mechanical crushing, or the like.
The negative electrode piece in the application can be a lithium copper composite belt, and the application is not particularly limited to the thickness of the lithium copper composite belt and the thickness of a lithium metal layer in the lithium copper composite belt, so long as the application purpose can be achieved. For example, the lithium copper composite tape may have a thickness of 30 μm to 80 μm, wherein the lithium metal layer may have a thickness of 5 μm to 60 μm. The thickness of the current collector is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the current collector is 4 μm to 20 μm.
The present application 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 thickness of the positive electrode current collector is 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. The thickness of the positive electrode active material layer is not particularly limited as long as the object of the present application can be achieved. For example, the thickness of the single-sided positive electrode active material layer is 20 μm to 120 μm. The porosity of the positive electrode active material layer is not particularly limited in this application, and may be selected according to actual needs as long as the object of this application can be achieved. For example, the porosity of the positive electrode active material layer may be 15% to 35%. The particle size of the positive electrode active material is not particularly limited in this application, and may be selected according to actual needs as long as the object of this application can be achieved. For example, the particle diameter Dv50 of the positive electrode active material may be 2 μm to 20 μm. Dv50 refers to the particle size that accumulates by 50% from a small volume in the particle size distribution on a volume basis of the material. In the present application, the positive electrode active material layer may be provided on one surface in the thickness direction of the positive electrode current collector, or may be provided on both surfaces in the thickness direction of the positive electrode current collector. 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 active material layer of the present application may further include a positive electrode conductive agent and a positive electrode binder. The positive electrode conductive agent and the positive electrode binder are not particularly limited in the present application as long as the objects of the present application can be achieved. For example, the positive electrode conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), carbon Nanotubes (CNTs), carbon fibers, graphene, metallic materials, or conductive polymers, which 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 positive electrode binder may include, but is not limited to, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethyleneoxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon.
The electrolyte of the present application also includes a nonaqueous solvent as a base solvent. The nonaqueous solvent is not particularly limited as long as the object of the present application can be achieved, and may include, for example, but not limited to, at least one of a carbonate compound, a carboxylate compound, an ether compound, or other organic solvents. The carbonate compound may include, but is not limited to, at least one of a chain carbonate compound or a cyclic carbonate 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 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, gamma-butyrolactone, decalactone, valerolactone, or caprolactone. The ether compound may include, but is not limited to, at least one of dimethyl ether, 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, 3-dioxolane, sulfolane, methyl sulfolane, 1, 3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, or trioctyl phosphate. The above nonaqueous solvent may be 5% to 95% by mass based on the mass of the electrolyte, and may be, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 45%, 55%, 65%, 70%, 75%, 80%, 86%, 88%, 90%, 93%, 94%, 95% or a range of any two values therebetween. In some embodiments, the electrolyte includes a fluorine-containing lithium salt and a nonaqueous solvent, which may be present in an amount of 35% to 95% by mass based on the mass of the electrolyte. In some embodiments, the electrolyte includes a fluorine-containing lithium salt, a nonaqueous solvent, and lithium nitrate, and the nonaqueous solvent may be present in an amount of 25% to 94.9% by mass based on the mass of the electrolyte. In some embodiments, the electrolyte includes a lithium fluoride salt, a nonaqueous solvent, and fluoroethylene carbonate, and the nonaqueous solvent may be present in an amount of 15% to 94% by mass based on the mass of the electrolyte. In some embodiments, the electrolyte includes a fluorine-containing lithium salt, a nonaqueous solvent, lithium nitrate, and fluoroethylene carbonate, and the nonaqueous solvent may be 5 to 93.9% by mass based on the mass of the electrolyte.
In the application, the diaphragm is used for separating the positive electrode plate and the negative electrode plate, preventing the internal short circuit of the electrochemical device, allowing electrolyte ions to pass freely, and not affecting the electrochemical charging and discharging process. The separator 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), polytetrafluoroethylene-based Polyolefin (PO) -based separator, polyester film (e.g., polyethylene terephthalate (PET) film), cellulose film, polyimide film (PI), polyamide film (PA), spandex or aramid film, and the like. The type of separator may include, but is not limited to, at least one of a woven film, a nonwoven film (nonwoven), a microporous film, a composite film, a rolled film, a spun film, or the like. The separator of the present application may have a porous structure, the porous layer is disposed on at least one surface of the separator, the porous layer includes inorganic particles and a binder, and the inorganic particles may include at least one of alumina, silica, magnesia, titania, hafnia, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttria, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. The binder may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. The size of the pore diameter of the porous structure is not particularly limited as long as the object of the present application can be achieved, and for example, the size of the pore diameter may be 0.01 μm to 1 μm. In the present application, 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 may be 5 μm to 500 μm.
The electrochemical device of the present application further includes a packaging bag for accommodating the positive electrode sheet, the separator, the negative electrode sheet, and the electrolyte, and other components known in the art of electrochemical devices, which are not limited in this application. The packaging bag is not particularly limited, and may be a packaging bag known in the art as long as the object of the present application can be achieved. For example, an aluminum plastic film package may be used.
The electrochemical device of the present application is not particularly limited, and may include any device in which an electrochemical reaction occurs. In one embodiment of the present application, the electrochemical device may include, but is not limited to: lithium metal batteries, and the like. The shape of the electrochemical device is not particularly limited as long as the object of the present application can be achieved. Such as, but not limited to, a prismatic battery, a shaped battery, a button battery, or the like.
The process of preparing the electrochemical device is well known to those skilled in the art, and the present application is not particularly limited, and may include, for example, but not limited to, the following steps: sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate, fixing four corners of the whole lamination structure by using an adhesive tape 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 an electrochemical device; or 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 requirement 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 the electrochemical device. In addition, an overcurrent prevention element, a guide plate, or the like may be placed in the package as needed, thereby preventing the pressure inside the electrochemical device from rising and overcharging and discharging.
A second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application. The electrochemical device provided in the first aspect of the present application has good cycle performance and expansion performance, so that the electronic device provided in the second aspect 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. In some embodiments, 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 portable cleaner, a portable CD-player, a mini-compact disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable audio recorder, a radio, a backup power source, 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 light, a camera, a household large battery or a lithium ion capacitor, and the like.
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. Unless otherwise specified, "parts" and "%" are mass references.
Test method and apparatus:
and (3) testing the number of circulation turns:
placing the lithium metal battery in an incubator at 25+/-2 ℃ for standing for 2 hours, wherein the cycle process is as follows: charging to 4.3V with constant current of 0.7C, charging to 0.025C with constant voltage of 4.3V, standing for 5min, discharging to 3.0V with 1C, and recording the discharge capacity of the lithium metal battery in the first cycle. And then repeating the charge-discharge cycle process according to the cycle process, and recording the discharge capacity of the lithium metal battery each time. At the 50 th, 100 th, 150 th, 200 th, 250 th and 300 th cycles, charge and discharge were performed as follows: the lithium metal battery was charged to 4.3V at a constant current of 0.05C, then charged to 0.025C at a constant voltage of 4.3V, left to stand for 5min, and discharged to 3.0V at 1C. And repeatedly carrying out charge and discharge circulation with the capacity of the first discharge being 100%, recording the number of turns of the lithium metal battery with the capacity retention rate reduced to 80%, taking 10 lithium metal batteries from each group, and calculating the average value of the number of turns of the lithium metal battery with the capacity retention rate reduced to 80%, namely the number of circulation turns of each group.
And testing the content of M element in the negative electrode plate:
and (3) after the lithium metal battery is circulated for 100 circles according to the circulation process in the circle number test, discharging to 3.0V at 1C, then disassembling the lithium metal battery, taking out the negative electrode plate, and immersing in dimethyl carbonate (DMC) for 20min to remove electrolyte. And then placing the negative electrode plate in an oven, baking at 80 ℃ for 12 hours to obtain a dried negative electrode plate, and weighing to obtain the quality of the negative electrode plate. Then, 0.1g of the negative pole piece sample is placed in a digestion tank and weighed. Adding 10mL of digestion reagent aqua regia (obtained by mixing concentrated hydrochloric acid and concentrated nitric acid according to the volume ratio of 3:1), shaking a digestion tank for 30min, and then digesting, wherein the volume of the digested sample is fixed by a volumetric flask. Finally, the mass c% of the M element was measured according to the us Environmental Protection Agency (EPA) standard EPA 3052-1996, eps 6010d-2014 using an inductively coupled plasma emission spectrometer (abbreviated as ICP-OES, model number Agilent 5800, available from Agilent corporation), c% = mass of the M element/mass of the negative electrode sheet x 100%.
And (3) testing the thickness of byproducts on the surface of the negative electrode plate:
and (3) after the lithium metal battery is circulated for 100 circles according to the circulation process in the circle number test, discharging to 3.0V at 1C, then disassembling the lithium metal battery, taking out the negative electrode plate, and soaking in dimethyl ether (DME) for 20min to remove electrolyte. And then placing the negative electrode plate in an oven, and baking at 80 ℃ for 12 hours to obtain the dried negative electrode plate. Then cutting along the thickness direction of the negative electrode plate by an ion cutting method to obtain a scanning electron microscope test sample, measuring the thickness of the byproducts on the surface of the negative electrode plate by a scanning electron microscope, and randomly measuring the thickness of the byproducts on the surface of the negative electrode plate at 5 positions to obtain an average value. As shown in fig. 3, a copper foil, a lithium metal layer and a byproduct layer are sequentially arranged from bottom to top. The smaller the thickness of the by-product on the surface of the negative electrode plate, the smaller the expansion of the negative electrode plate, and the better the expansion performance of the lithium metal battery.
Example 1-1
< preparation of Positive electrode sheet >
Lithium manganate (LiMn) as a positive electrode active material 2 O 4 Dv50=8μm), conductive carbon black (Super P) as a conductive agent, polyvinylidene fluoride (PVDF) as a binder, and N-methylpyrrolidone (NMP) as a solvent were mixed in a mass ratio of 97.5:1:1.5, and the mixture was blended to form a positive electrode slurry having a solid content of 75wt%, and stirred uniformly. Uniformly coating the slurry on one surface of an aluminum foil of a positive electrode current collector with the thickness of 13 mu m, and drying at 90 ℃ to obtain a positive electrode plate with a positive electrode active material layer with the thickness of 50 mu m and a single-sided coating positive electrode active material; after the coating is completed, the positive electrode plate is cut into a specification with the diameter of 14mm for standby.
< preparation of negative electrode sheet >
The negative electrode plate adopts a lithium copper composite belt (supplied by Tianjin, energy lithium industry Co., ltd.) and is directly punched and cut into a specification with the diameter of 18mm for later use. The thickness of the lithium copper composite tape was 50 μm, with the thickness of the lithium metal layer being 30 μm.
< preparation of electrolyte >
In a glove box with a dry argon atmosphere, firstly mixing a basic solvent of 1, 3-Dioxolane (DOL) and dimethyl ether (DME) in a volume ratio of 1:1, and then adding a fluorine-containing lithium salt LiTFSI into the basic solvent to dissolve and uniformly mix to obtain an electrolyte. Based on the mass of the electrolyte, the mass percentage content C% of the fluorine-containing lithium salt LiTFSI is 40%, and the balance is the base solvent.
< separator >
Polyethylene film (PE film, supplied by Entek) having a thickness of 15 μm was used as the separator.
< preparation of lithium Metal Battery >
And in a glove box with a dry argon atmosphere, arranging the negative electrode plate, the diaphragm and the positive electrode plate from bottom to top in sequence, putting the lithium battery into an aluminum plastic film packaging bag, injecting electrolyte, and carrying out the procedures of vacuum packaging, standing, shaping, capacity testing, degassing, trimming and the like to obtain the single-layer laminated lithium metal battery.
Examples 1-2 to 1-8
The procedure of example 1-1 was repeated except that the type of the positive electrode active material was adjusted in accordance with Table 1 in the preparation of < preparation of positive electrode sheet >.
Examples 1 to 9
The procedure of example 1-1 was repeated except that lithium iron phosphate+lithium manganate (the mass ratio of lithium iron phosphate to lithium manganate is 1:1) was used as the positive electrode active material in the preparation of < preparation of positive electrode sheet >.
Examples 1 to 10
The procedure of example 1-1 was repeated except that lithium iron phosphate-doped manganese carbonate (mass ratio of lithium iron phosphate to manganese carbonate: 92.5:5) was used as the positive electrode active material in the preparation of < preparation of positive electrode sheet >.
Examples 1 to 11
The procedure of example 1-1 was repeated except that lithium iron phosphate-doped manganese carbonate (mass ratio of lithium iron phosphate to manganese carbonate: 95:5) was used as the positive electrode active material in the preparation of < preparation of positive electrode sheet >.
Examples 1 to 12
The procedure of example 1-1 was repeated except that lithium iron phosphate doped lithium manganate (mass ratio of lithium iron phosphate to lithium manganate: 80:20) was used as the positive electrode active material in the preparation of < preparation of positive electrode sheet >.
Examples 1 to 13
The procedure of example 1-1 was repeated except that Dv50=4.8 μm of lithium manganate was used as the positive electrode active material.
Examples 1 to 14
The procedure of example 1-1 was repeated except that Dv50=3.5 μm of lithium manganate was used as the positive electrode active material.
Examples 1 to 15 to 1 to 19
The procedure of example 1-1 was repeated, except that the mass percentage C of the fluorine-containing lithium salt and the mass percentage of the base solvent were changed as shown in Table 1 in the < preparation of electrolyte >.
Examples 2-1 to 2-7
The procedure of example 1-1 was repeated except that in the step of < preparation of electrolyte >, lithium nitrate was added as shown in Table 2, and the mass percentage D of lithium nitrate, the mass percentage of the base solvent and the mass percentage of the fluorine-containing lithium salt were adjusted as shown in Table 2.
Examples 2 to 8 to 2 to 13
The procedure of examples 2 to 4 was repeated except that the type of the positive electrode active material was adjusted in accordance with Table 2 in the preparation of < preparation of positive electrode sheet >.
Examples 2 to 14 to 2 to 15
The procedure of example 1-1 was repeated except that in the step of < preparation of electrolyte >, lithium nitrate was added as shown in Table 2, and the mass percentage D of lithium nitrate, the mass percentage of the base solvent and the mass percentage of the fluorine-containing lithium salt were adjusted as shown in Table 2.
Examples 3-1 to 3-5
The procedure of example 1-1 was repeated, except that fluoroethylene carbonate was added as shown in Table 3 and the mass percentage of fluoroethylene carbonate E, the mass percentage of the base solvent and the mass percentage of the fluorine-containing lithium salt were changed as shown in Table 3.
Examples 3 to 6
The procedure of examples 1 to 14 was repeated, except that Dv50=3.2 μm lithium manganate was used as the positive electrode active material, fluoroethylene carbonate was added to the solution < preparation of electrolyte > according to Table 3, and the mass percentage of fluoroethylene carbonate E, the mass percentage of the base solvent and the mass percentage of the fluorine-containing lithium salt were changed according to Table 3.
Examples 3 to 7
The procedure of examples 1 to 11 was repeated, except that fluoroethylene carbonate was added as shown in Table 3 and the mass% of fluoroethylene carbonate, the mass% of the base solvent and the mass% of the fluorine-containing lithium salt were changed as shown in Table 3.
Examples 3 to 8 to 3 to 13
The procedure of example 3-3 was repeated except that the type of the positive electrode active material was adjusted in accordance with Table 3 in the preparation of < preparation of positive electrode sheet >.
Examples 4-1 to 4-3
The procedure of example 1-1 was repeated except that in the < preparation of electrolyte > according to Table 4, lithium nitrate and fluoroethylene carbonate were added, and the mass% of lithium nitrate D% and the mass% of fluoroethylene carbonate E% were adjusted according to Table 3, the mass% of the base solvent was changed, and the mass% of the fluorine-containing lithium salt was unchanged.
Comparative example 1
The procedure of example 1-1 was repeated except that the following positive electrode active material was used for the preparation of the positive electrode sheet.
< preparation of cathode active Material >
Adding absolute ethyl alcohol into aluminum hydroxide, dispersing for 10min at the speed of 1000r/min, continuously adding absolute ethyl alcohol, dispersing for 30min at the speed of 2000r/min to obtain a first suspension with the solid content of 60wt%, drying the first suspension, and calcining for 10h at the temperature of 700 ℃ to obtain the aluminum oxide material.
Adding lithium manganate (LiMn) to an alumina material 2 O 4 Dv50=8 μm), then absolute ethanol was added and dispersed at a rate of 500r/min for 5min, and stirred at a rate of 1000r/min for 30min, giving a second suspension with a solids content of 65 w%. Then reducing the stirring rate to 300r/min, heating for 6 hours under the water bath condition of 80 ℃, removing absolute ethyl alcohol in the second suspension to obtain mixed powder, calcining the mixed powder for 10 hours under the condition of 750 ℃, cooling and grinding to obtain an anode active material, and marking the anode active material as aluminum oxide@lithium manganate; wherein the mass percentage of the alumina is 0.8% based on the mass of the positive electrode active material, and the particle diameter Dv50 of the positive electrode active material is 6μm。
Comparative example 2
The procedure of example 1-1 was repeated except that Dv50=1.8 μm of lithium manganate was used as the positive electrode active material.
Comparative examples 3 to 4
The procedure of example 1-1 was repeated, except that the mass percentage C of the fluorine-containing lithium salt and the mass percentage of the base solvent were changed as shown in Table 1 in the < preparation of electrolyte >.
Comparative example 5
The procedure of example 1-1 was repeated except that lithium manganate having a Dv 50=2 μm was used as the positive electrode active material in the preparation of < positive electrode sheet > and the mass percentage of the fluorine-containing lithium salt C and the mass percentage of the base solvent were changed as shown in table 1 in the < preparation of electrolyte >.
The relevant parameters and performance tests for each example and each comparative example are shown in tables 1 to 4.
TABLE 1
Note that: the "/" in Table 1 indicates that the parameter is not present, superscript " a The particle diameter Dv50 of lithium manganate is 4.8 mu m, which is marked with the superscript' b The particle diameter Dv50 of lithium manganate is 3.5 mu m, which is marked with the superscript' c The particle diameter Dv50 of lithium manganate is 1.8 μm, which is marked with the superscript' d "the particle diameter Dv50 of lithium manganate is 2.0 μm.
As can be seen from examples 1-1 to 1-19 and comparative examples 1 to 5, the positive electrode active material includes M element, the negative electrode tab includes lithium metal and M element, and the value of X is regulated within the scope of the present application, the electrolyte includes fluorine-containing lithium salt and the value of C is regulated within the scope of the present application, the thickness of the by-product on the surface of the negative electrode tab of the lithium metal battery is smaller, the number of cycles of the lithium metal battery is greater, indicating that the lithium metal battery has better expansion performance and cycle performance.
It can be seen from examples 1-1 to 1-14 and comparative examples 1 to 2 that when the value of X is too small or too large, the thickness of the by-product on the surface of the negative electrode sheet is large, and the number of cycles of the lithium metal battery is small. Through regulating and controlling the value of X in the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, the cycle number of the lithium metal battery is more, and the lithium metal battery is better in expansion performance and cycle performance.
It can be seen from examples 1 to 15 to 1 to 19 and comparative examples 3 to 4 that when the value of C is too small or too large, the thickness of the by-product on the surface of the negative electrode sheet is large, and the number of cycles of the lithium metal battery is small. Through regulating and controlling the value of C in the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, the cycle number of the lithium metal battery is more, and the lithium metal battery is better in expansion performance and cycle performance.
The value of X/C generally affects the swelling and cycling performance of lithium metal batteries. From examples 1-1 to 1-19, it can be seen that the value of X/C is controlled within the range of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, the cycle number of the lithium metal battery is more, and the lithium metal battery has good expansion performance and cycle performance.
TABLE 2
Note that: the "/" in Table 2 indicates that this parameter is not present.
The electrolyte comprising lithium nitrate in mass% D% of lithium nitrate generally affects the cycle performance of lithium metal batteries. It can be seen from examples 1-1, 2-1 to 2-7 and 2-14 to 2-15 that the electrolyte comprises lithium nitrate and the value of D is regulated within the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, and the cycle number of the lithium metal battery is more. The positive electrode active material comprises M element, the negative electrode plate comprises lithium metal and M element, and the electrolyte comprises fluorine-containing lithium salt, and lithium nitrate is further introduced into the electrolyte, so that the lithium metal battery has good expansion performance and better cycle performance.
The value of X/D generally affects the swelling and cycling performance of lithium metal batteries. From examples 2-1 to 2-15, it can be seen that the value of X/D is controlled within the range of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, the cycle number of the lithium metal battery is more, and the lithium metal battery has good expansion performance and cycle performance.
TABLE 3 Table 3
Note that: the "/" in Table 3 indicates that the parameter is not present, superscript " a "the particle diameter Dv50 of lithium manganate is 3.2 μm.
The electrolyte comprising fluoroethylene carbonate and the mass percent E% of fluoroethylene carbonate generally affect the cycle performance of lithium metal batteries. It can be seen from examples 1-1, 3-1 to 3-5 that the electrolyte comprises fluoroethylene carbonate and the value of E is regulated and controlled within the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, and the cycle number of the lithium metal battery is more. The positive electrode active material comprises M element, the negative electrode plate comprises lithium metal and M element, and the electrolyte comprises fluorine-containing lithium salt, and fluoroethylene carbonate is further introduced into the electrolyte, so that the lithium metal battery has good expansion performance and better cycle performance.
The value of X/E generally affects the swelling and cycling performance of lithium metal batteries. From examples 1-1 to 1-4, examples 1-6 to 1-8, examples 1-13 to 1-14, and examples 3-1 to 3-13, it can be seen that the value of X/E is regulated within the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, the number of cycles of the lithium metal battery is more, and the lithium metal battery has good expansion performance and better cycle performance.
TABLE 4 Table 4
Note that: the "/" in Table 4 indicates that this parameter is not present.
It can be seen from examples 1-1, 2-4, 3-3, and 4-1 to 4-3 that lithium nitrate and fluoroethylene carbonate are simultaneously introduced into the electrolyte and the values of D and E are regulated within the scope of the application, the thickness of the by-product on the surface of the negative electrode plate of the lithium metal battery is smaller, and the cycle number of the lithium metal battery is more. The positive electrode active material comprises M element, the negative electrode plate comprises lithium metal and M element, and the electrolyte comprises fluorine-containing lithium salt, and lithium nitrate and fluoroethylene carbonate are further introduced into the electrolyte at the same time, and the content of the lithium nitrate and fluoroethylene carbonate is regulated and controlled within the scope of the application, so that the lithium metal battery has better expansion performance and cycle performance.
Fig. 2 is an SEM photograph of a cross section of the negative electrode tab of the lithium metal battery of comparative example 1 in the thickness direction after cycling, and in fig. 2, the following steps are sequentially performed from top to bottom: a byproduct layer, a lithium metal layer and a copper foil. Fig. 3 is an SEM photograph of a cross section of the negative electrode tab of the lithium metal battery of example 1-1 in the thickness direction after cycling, and the distribution of each layer in fig. 3 is the same as that in fig. 2. As can be seen from fig. 2 and 3, the lithium metal battery of comparative example 1 has more byproducts accumulated on the surface of the negative electrode tab after 100 cycles, and has a larger thickness. The lithium metal battery of the example 1-1 has fewer byproducts accumulated on the surface of the negative electrode plate after being cycled for 100 circles, and has smaller thickness. The lithium metal battery provided by the embodiment of the application has less byproducts on the surface of the negative electrode plate.
As can be seen from fig. 4, the cycle capacity retention rate of the lithium metal battery of comparative example 1 was reduced to 80% or less at the 190 th cycle under the same cycle conditions, the capacity of the lithium metal battery was reduced more rapidly, and the number of cycles was smaller; the capacity retention rate of the lithium metal battery in the embodiment 1-1 of the application is still up to 92% at the 299 th turn, and the capacity of the lithium metal battery is attenuated to be lower than 80% after the lithium metal battery circulates to the 346 th turn, so that the lithium metal battery in the embodiment 1-1 of the application has slower capacity attenuation and more circulating turns, namely better circulating performance.
The foregoing description of the preferred embodiments of the present invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, alternatives, and alternatives falling within the spirit and scope of the invention.

Claims (10)

1. An electrochemical device is characterized by comprising a positive electrode plate, a negative electrode plate, electrolyte and a diaphragm;
the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, the positive electrode active material comprises an M element, and the M element comprises at least one of Mn, ni, co or Fe;
The negative electrode piece comprises an M element, and the mass percentage content X% of the M element is 0.05-1% based on the mass of the negative electrode piece;
the electrolyte comprises fluorine-containing lithium salt, and the mass percentage content C% of the fluorine-containing lithium salt is 5-65% based on the mass of the electrolyte.
2. The electrochemical device of claim 1, wherein the electrolyte further comprises lithium nitrate, the mass percent content d% of the lithium nitrate being 0.1% to 10% based on the mass of the electrolyte; X/D satisfies: X/D is more than or equal to 0.01 and less than or equal to 3.
3. The electrochemical device of claim 1, wherein the electrolyte further comprises fluoroethylene carbonate, the mass percent e% of the fluoroethylene carbonate being 1% to 20%, X/E being satisfied, based on the mass of the electrolyte; X/E is more than or equal to 0.0025 and less than or equal to 1.
4. The electrochemical device of claim 1, wherein the fluorine-containing lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethylsulfonyl imide, lithium difluorooxalato borate, lithium hexafluoroborate, or lithium hexafluoroarsenate.
5. The electrochemical device according to claim 1, wherein the mass percentage content x% of the M element is 0.1% to 0.5% based on the mass of the negative electrode tab.
6. The electrochemical device of claim 1, wherein X/C satisfies: X/C is more than or equal to 0.0007 and less than or equal to 0.2.
7. The electrochemical device of claim 1, wherein the positive electrode active material comprises at least one of lithium manganate, lithium nickel cobalt manganate, lithium rich manganese, lithium cobaltate, lithium nickelate, lithium iron phosphate, or manganese carbonate doped lithium iron phosphate.
8. The electrochemical device of claim 1, wherein the negative electrode tab comprises at least one of lithium metal or a current collector comprising any one of copper foil, titanium foil, stainless steel, carbon paper, and graphene paper.
9. The electrochemical device of claim 1, wherein the electrochemical device meets at least one of the following characteristics:
(1) The mass percentage content C% of the fluorine-containing lithium salt is 20-56%;
(2) The electrolyte comprises lithium nitrate, wherein the mass percentage content D% of the lithium nitrate is 0.5-5% based on the mass of the electrolyte;
（3）0.0007≤X/C≤0.1。
10. an electronic device, characterized in that it comprises the electrochemical device according to any one of claims 1 to 9.
CN202310827506.9A 2023-07-06 2023-07-06 Electrochemical device and electronic device Pending CN116565293A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310827506.9A CN116565293A (en) 2023-07-06 2023-07-06 Electrochemical device and electronic device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310827506.9A CN116565293A (en) 2023-07-06 2023-07-06 Electrochemical device and electronic device

Publications (1)

Publication Number Publication Date
CN116565293A true CN116565293A (en) 2023-08-08

Family

ID=87486481

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310827506.9A Pending CN116565293A (en) 2023-07-06 2023-07-06 Electrochemical device and electronic device

Country Status (1)

Country Link
CN (1) CN116565293A (en)

Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016001586A (en) * 2013-09-25 2016-01-07 国立大学法人 東京大学 Nonaqueous electrolyte secondary battery
CN105283979A (en) * 2013-07-10 2016-01-27 日本瑞翁株式会社 Porous film composition for lithium ion secondary batteries, separator for lithium ion secondary batteries, electrode for lithium ion secondary batteries, and lithium ion secondary battery
CN105324868A (en) * 2013-07-10 2016-02-10 日本瑞翁株式会社 Adhesive for lithium ion secondary batteries, separator for lithium ion secondary batteries, and lithium ion secondary battery
CN107994206A (en) * 2016-10-26 2018-05-04 宁德时代新能源科技股份有限公司 Lithium ion battery and cathode plate thereof
CN107994207A (en) * 2016-10-26 2018-05-04 宁德时代新能源科技股份有限公司 Lithium ion battery and cathode plate thereof
CN111380996A (en) * 2018-12-29 2020-07-07 宁德时代新能源科技股份有限公司 Rapid detection method for cycle life of anode material
CN112103561A (en) * 2020-09-21 2020-12-18 宁德新能源科技有限公司 Electrolyte and electrochemical device
CN114388732A (en) * 2021-12-22 2022-04-22 东莞新能安科技有限公司 Electrochemical device and electronic device
CN114597488A (en) * 2020-12-04 2022-06-07 深圳新宙邦科技股份有限公司 Non-aqueous electrolyte and lithium ion battery
CN114678592A (en) * 2022-05-30 2022-06-28 深圳澳睿新能源科技有限公司 Non-aqueous electrolyte containing cyano cyclic amine compound, lithium ion battery and application thereof
CN115332626A (en) * 2022-08-30 2022-11-11 珠海冠宇动力电池有限公司 Electrolyte and battery comprising same
CN115548439A (en) * 2021-06-30 2022-12-30 比亚迪股份有限公司 Electrolyte for secondary battery and secondary battery
CN115842109A (en) * 2021-09-29 2023-03-24 宁德时代新能源科技股份有限公司 Positive electrode material and preparation method thereof, secondary battery, battery module, battery pack and electric device
CN115986211A (en) * 2021-10-14 2023-04-18 中国科学院物理研究所 Low-temperature electrolyte of lithium battery and lithium battery
CN115995531A (en) * 2022-10-13 2023-04-21 欣旺达电动汽车电池有限公司 Positive electrode active material, positive electrode plate, lithium ion battery and application of positive electrode active material and positive electrode plate
CN116247300A (en) * 2023-05-09 2023-06-09 蓝固(湖州)新能源科技有限公司 High-voltage electrolyte additive, electrolyte and lithium ion battery
CN116365049A (en) * 2023-04-03 2023-06-30 欣旺达电动汽车电池有限公司 Secondary battery and electric equipment

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105283979A (en) * 2013-07-10 2016-01-27 日本瑞翁株式会社 Porous film composition for lithium ion secondary batteries, separator for lithium ion secondary batteries, electrode for lithium ion secondary batteries, and lithium ion secondary battery
CN105324868A (en) * 2013-07-10 2016-02-10 日本瑞翁株式会社 Adhesive for lithium ion secondary batteries, separator for lithium ion secondary batteries, and lithium ion secondary battery
JP2016001586A (en) * 2013-09-25 2016-01-07 国立大学法人 東京大学 Nonaqueous electrolyte secondary battery
CN107994206A (en) * 2016-10-26 2018-05-04 宁德时代新能源科技股份有限公司 Lithium ion battery and cathode plate thereof
CN107994207A (en) * 2016-10-26 2018-05-04 宁德时代新能源科技股份有限公司 Lithium ion battery and cathode plate thereof
CN111380996A (en) * 2018-12-29 2020-07-07 宁德时代新能源科技股份有限公司 Rapid detection method for cycle life of anode material
CN112103561A (en) * 2020-09-21 2020-12-18 宁德新能源科技有限公司 Electrolyte and electrochemical device
CN114597488A (en) * 2020-12-04 2022-06-07 深圳新宙邦科技股份有限公司 Non-aqueous electrolyte and lithium ion battery
CN115548439A (en) * 2021-06-30 2022-12-30 比亚迪股份有限公司 Electrolyte for secondary battery and secondary battery
CN115842109A (en) * 2021-09-29 2023-03-24 宁德时代新能源科技股份有限公司 Positive electrode material and preparation method thereof, secondary battery, battery module, battery pack and electric device
CN115986211A (en) * 2021-10-14 2023-04-18 中国科学院物理研究所 Low-temperature electrolyte of lithium battery and lithium battery
CN114388732A (en) * 2021-12-22 2022-04-22 东莞新能安科技有限公司 Electrochemical device and electronic device
CN114678592A (en) * 2022-05-30 2022-06-28 深圳澳睿新能源科技有限公司 Non-aqueous electrolyte containing cyano cyclic amine compound, lithium ion battery and application thereof
CN115332626A (en) * 2022-08-30 2022-11-11 珠海冠宇动力电池有限公司 Electrolyte and battery comprising same
CN115995531A (en) * 2022-10-13 2023-04-21 欣旺达电动汽车电池有限公司 Positive electrode active material, positive electrode plate, lithium ion battery and application of positive electrode active material and positive electrode plate
CN116365049A (en) * 2023-04-03 2023-06-30 欣旺达电动汽车电池有限公司 Secondary battery and electric equipment
CN116247300A (en) * 2023-05-09 2023-06-09 蓝固(湖州)新能源科技有限公司 High-voltage electrolyte additive, electrolyte and lithium ion battery

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
陈玉华: "新型清洁能源技术", 知识产权出版社, pages: 44 *

Similar Documents

Publication Publication Date Title
CN111029543B (en) Negative electrode material, and electrochemical device and electronic device comprising same
CN114730883B (en) Negative electrode composite material and application thereof
CN113812021A (en) Electrochemical device and electronic device
CN114097113A (en) Positive electrode lithium supplement material, positive electrode plate containing material and electrochemical device
US20220320500A1 (en) Electrochemical device and an electronic device
CN115053379A (en) Electrochemical device and electronic device
CN114144919A (en) Positive pole piece, electrochemical device comprising positive pole piece and electronic device
CN114097111A (en) Positive electrode lithium supplement material, positive electrode plate containing material and electrochemical device
CN116613274A (en) Negative electrode sheet, secondary battery including the same, and electronic device
CN116344766A (en) Secondary battery and electronic device
US20220310998A1 (en) Positive electrode plate, and electrochemical apparatus and electronic apparatus containing such positive electrode plate
WO2023039748A9 (en) Electrochemical device and electronic device
KR20230093433A (en) Electrochemical and electronic devices
CN116565292B (en) Electrochemical device and electronic device
CN114097112A (en) Positive electrode lithium supplement material, positive electrode plate containing material and electrochemical device
CN116565293A (en) Electrochemical device and electronic device
CN116544489B (en) Electrochemical device and electronic device
CN116706076B (en) Negative electrode material, negative electrode plate, electrochemical device and electronic device
CN114843518B (en) Negative electrode active material, method for producing negative electrode active material, and electrochemical device
CN117712492A (en) Secondary battery and electronic device
CN117276465A (en) Battery pole piece, secondary battery and device
CN117712491A (en) Secondary battery and electronic device
CN117728025A (en) Secondary battery and electronic device
CN117525406A (en) Electrochemical device and electronic apparatus
CN117480634A (en) Negative electrode plate, electrochemical device and electronic device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination