CN114094076B - Negative plate and lithium ion battery comprising same - Google Patents
Negative plate and lithium ion battery comprising same Download PDFInfo
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- CN114094076B CN114094076B CN202111348705.9A CN202111348705A CN114094076B CN 114094076 B CN114094076 B CN 114094076B CN 202111348705 A CN202111348705 A CN 202111348705A CN 114094076 B CN114094076 B CN 114094076B
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 37
- 239000006183 anode active material Substances 0.000 claims abstract description 61
- 239000007773 negative electrode material Substances 0.000 claims abstract description 54
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 5
- 239000010439 graphite Substances 0.000 claims abstract description 5
- 239000002245 particle Substances 0.000 claims description 20
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- 238000000034 method Methods 0.000 claims description 14
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- 239000010410 layer Substances 0.000 description 42
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 11
- 239000011267 electrode slurry Substances 0.000 description 11
- 229910052744 lithium Inorganic materials 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 239000011229 interlayer Substances 0.000 description 8
- 239000002077 nanosphere Substances 0.000 description 8
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
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- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 241001591024 Samea Species 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/581—Chalcogenides or intercalation compounds thereof
- H01M4/5815—Sulfides
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a negative electrode plate and a lithium ion battery comprising the same, wherein the negative electrode plate comprises a negative electrode current collector, a first negative electrode active material layer and a second negative electrode active material layer; the first anode active material layer comprises a first anode active material, the second anode active material layer comprises a second anode active material, the first anode active material is selected from graphite, and the second anode active material is selected from SnS-MoS 2 . By introducing SnS-MoS into the negative electrode sheet 2 The quick charge performance of the lithium ion battery can be improved, and the expansion and crushing of the negative electrode active material in the negative electrode plate are improved, so that the volume expansion of the negative electrode plate is relieved, and the long-cycle stability of the lithium ion battery is improved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a negative plate and a lithium ion battery comprising the negative plate.
Background
With the development of lithium ion secondary batteries, consumers have increasingly demanded charge speed, endurance time and safety performance. However, with the increase of the charging speed, in the case of high-rate charging, the negative electrode sheet of the lithium ion battery is easy to generate a lithium precipitation phenomenon on the surface of the negative electrode due to the non-uniformity of the electrode potential and the electrolyte concentration, and besides, the negative electrode sheet is easy to generate a phenomenon that the negative electrode active material is expanded and broken, which seriously affects the performance of the lithium ion battery.
Disclosure of Invention
In order to solve the problems that lithium is easy to be separated out from the surface of a negative electrode caused by non-uniformity of electrode potential and electrolyte concentration of a negative electrode plate under the condition of high-rate charging of the conventional lithium ion battery and a negative electrode active material in the negative electrode plate is expanded and broken, the invention provides the negative electrode plate and the lithium ion battery comprising the negative electrode plate. The lithium ion battery assembled by the negative electrode plates has excellent cycle performance under the condition of high multiplying power, meanwhile, the occurrence of lithium precipitation of the negative electrode plates can be avoided, and in addition, the expansion and crushing of the negative electrode active materials in the negative electrode plates can be improved, so that the volume expansion of the negative electrode plates is relieved, and the long cycle stability of the lithium ion battery is improved.
In the present invention, the term "large magnification" refers to a charging magnification of 2C or more.
The invention aims at realizing the following technical scheme:
a negative electrode sheet including a negative electrode current collector, a first negative electrode active material layer, and a second negative electrode active material layer; the first negative electrode active material layer is arranged on the first surface of the negative electrode current collector, and the second negative electrode active material layer is arranged on the surface of the first negative electrode active material layer;
the first anode active material layer comprises a first anode active material, the second anode active material layer comprises a second anode active material, the first anode active material is selected from graphite, and the second anode active material is selected from SnS-MoS 2 。
According to the invention, the SnS-MoS 2 Having an interlayer covalent assembly structure.
According to the invention, the SnS-MoS 2 Is formed by covalently connecting MoS with SnS nano-dots 2 Hollow super-assemblies made of nanosheets, i.e. SnS-MoS 2 Is formed by covalently connecting MoS with SnS nano-dots 2 The hollow structure with interlayer covalent assembly made of the nano-sheet can be used for high-rate lithium storage.
According to the invention, the SnS-MoS 2 The preparation method comprises the following steps:
MoS is firstly carried out 2 Nano-sheet deposited on SiO modified by sulfonic acid group 2 On nanospheres, snS is then deposited on MoS 2 On nanosheets, then SnS anchored MoS 2 The nanometer sheet is covalently assembled into a hollow super assembly, namely the SnS-MoS 2 。
According to the invention, the SnS-MoS 2 Wherein the mass percentage of SnS is 20-50 wt%, preferably 30wt％～35wt％。
Illustratively, the SnS-MoS 2 The structure with interlayer covalent assembly is prepared by covalent assembly through a hydrothermal method. Specifically, the preparation method comprises the following steps:
first, siO modified with sulfonic acid group 2 The nanospheres are used as templates and dispersed in a matrix containing Na 2 MoO 4 、Na 2 SnO 3 And CH (CH) 3 CSNH 2 Is added to the reaction solution; then, carrying out hydrothermal reaction to obtain the SnS-MoS with the interlayer covalent assembly structure 2 。
Wherein the temperature of the hydrothermal reaction is 160-300 ℃, such as 200 ℃; the hydrothermal reaction time is 8 to 16 hours, such as 12 hours.
During the hydrothermal reaction, due to the sulfonic acid group and MoO 4 2- Interaction between anions, moS with lower Ksp value 2 Preferably with a small MoS 2 Nano-sheet form is deposited on SiO 2 The surface of the nanospheres; the active surface acts as nucleation sites to further promote deposition of SnS nanodots. SnS nanodots at MoS 2 The tight anchoring of the nanoplatelet surfaces may limit the growth of nanoplatelet thickness, promoting the growth of nanoplatelets along a plane. Subsequently, moS with large overlapping boundary regions 2 Continuous growth of nanoplatelets triggered MoS using SnS nanodots as junctions between nanoplatelets 2 Covalent assembly of nanoplatelets, resulting in MoS 2 The SnS nano-sheet is completely covered on the whole SiO 2 On the nanospheres. Finally, moS 2 SnS removes SiO by simple etching process 2 Obtaining SnS-MoS with interlayer covalent assembly structure after template of nanosphere 2 。
In the research process of the invention, electrochemical theoretical calculation shows that in the negative plate, the potential of the active material layer close to the surface of the diaphragm is lower, the lithium separation risk is larger, and the overall expansion rate of the lithium ion battery is further influenced. The scheme of the invention is based on the scheme, wherein the SnS-MoS 2 Has an interlayer covalent assembly structure, so that the interlayer covalent assembly structure has lower Li ion diffusion barrier and lower circumferential directionAnd radial tensile stress, but lower Li ion diffusion barrier can promote the quick charge performance of lithium ion battery, and lower hoop and radial tensile stress can improve the expansion breakage of negative electrode active material in the negative electrode piece to alleviate the volume expansion of negative electrode piece, improve the long cycle stability of lithium ion battery.
According to the present invention, the first negative electrode active material has a median particle diameter Dv 1 50 The method meets the following conditions: dv is less than or equal to 1 mu m 1 50 Less than or equal to 50 mu m, preferably meets the following conditions: dv is less than or equal to 5 mu m 1 50 Less than or equal to 25 mu m; for example, the median particle diameter Dv of the first anode active material 1 50 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or 50 μm.
According to the present invention, the second anode active material has a median particle diameter Dv 2 50 The method meets the following conditions: dv of 100nm or less 2 50 Less than or equal to 600nm; for example, the median particle diameter Dv of the second anode active material 2 50 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm or 600nm.
According to the present invention, the first negative electrode active material has a median particle diameter Dv 1 50 And the median particle diameter Dv of the second anode active material 2 50 The ratio of (2) is as follows: dv is 8 to or less 1 50 /Dv 2 50 Less than or equal to 200, e.g., the median particle diameter Dv of the first negative electrode active material 1 50 And the median particle diameter Dv of the second anode active material 2 50 Is 8, 10, 20, 30, 40, 50, 75, 80, 90, 100, 120, 150, 180, or 200. When Dv is 1 50 /Dv 2 50 <8, it is shown that the particle size of the second negative electrode active material is too large, at which time the conductivity of the second negative electrode active material itself is lowered, the rate performance is deteriorated, and Dv 1 50 /Dv 2 50 >200 shows that the particle size of the second negative electrode active material is too small, and at this time, the secondary reaction on the surface of the second negative electrode active material increases, and the cell cycle capacity retention rate becomes low.
According to the present invention, the thickness L of the first anode active material layer 1 10 to 200. Mu.m, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm.
According to the present invention, the thickness L of the first anode active material layer 1 And a thickness L of the second anode active material layer 2 Ratio L of (2) 2 /L 1 The method meets the following conditions: l is more than or equal to 0.05 2 /L 1 Less than or equal to 0.15, for example, the thickness L of the first anode active material layer 1 And a thickness L of the second anode active material layer 2 Ratio L of (2) 2 /L 1 0.05, 0.1 or 0.15. When L 2 /L 1 <0.05, the second negative electrode active material layer is too small in thickness to sufficiently improve the rate performance of the whole electrode sheet, when L 2 /L 1 >At 0.15, it is shown that the thickness of the second negative electrode active material is too large, and at this time, the side reaction on the surface of the second negative electrode active material increases, and the cell cycle capacity retention rate becomes low.
According to the present invention, the negative electrode current collector is selected from copper foil.
According to the present invention, the negative electrode current collector has a thickness of 6 μm to 12 μm.
According to the present invention, the first anode active material layer is further provided on a second surface of the anode current collector opposite to the first surface, and the second anode active material layer is provided on the first anode active material layer surface.
According to the present invention, the first anode active material layer further includes a first conductive agent and a first binder.
According to the present invention, the second anode active material layer further includes a second conductive agent and a second binder.
According to the invention, the first anode active material layer comprises the following components in percentage by mass: 90 to 99.2wt% of a first negative active material, 0.2 to 4wt% of a first conductive agent, and 0.6 to 6wt% of a first binder.
According to the invention, the second anode active material layer comprises the following components in percentage by mass: 90 to 99.2wt% of a second negative active material, 0.2 to 4wt% of a second conductive agent, and 0.6 to 6wt% of a second binder.
According to the present invention, the first negative active material is selected from artificial graphite and/or natural graphite.
According to the present invention, the first conductive agent and the second conductive agent are the same or different and are independently selected from one or more of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder, and conductive fiber.
According to the present invention, the first binder and the second binder are the same or different and are independently selected from one or more of polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.
The invention also provides a preparation method of the negative plate, which comprises the following steps:
1) Preparing a slurry for forming a first anode active material layer and a slurry for forming a second anode active material layer, respectively;
2) The slurry for forming the first anode active material layer and the slurry for forming the second anode active material layer are coated on the first surface of the anode current collector by using a double-layer coater, so that the anode sheet is prepared.
According to the present invention, in step 1), the solid content of the slurry forming the first anode active material layer and the slurry forming the second anode active material layer is 40wt% to 50wt%.
According to the present invention, in step 2), the slurry forming the first anode active material layer and the slurry forming the second anode active material layer are coated on a second surface of the anode current collector opposite to the first surface, to prepare the anode sheet.
The invention also provides a lithium ion battery, which comprises the negative plate.
According to the invention, the lithium ion battery further comprises a positive plate, a diaphragm and electrolyte.
The invention has the beneficial effects that:
the invention provides a negative plate and lithium ion battery comprising the sameA sub-battery, the negative electrode tab including a negative electrode current collector, a first negative electrode active material layer, and a second negative electrode active material layer; the first anode active material layer comprises a first anode active material, the second anode active material layer comprises a second anode active material, the first anode active material is selected from graphite, and the second anode active material is selected from SnS-MoS 2 。
By introducing SnS-MoS into the negative electrode sheet 2 The quick charge performance of the lithium ion battery can be improved, and the expansion and crushing of the negative electrode active material in the negative electrode plate are improved, so that the volume expansion of the negative electrode plate is relieved, and the long-cycle stability of the lithium ion battery is improved.
Drawings
Fig. 1 is a schematic view of a negative electrode sheet according to a preferred embodiment of the present invention.
Reference numerals: 1 is a negative current collector; 2 is a first anode active material layer; and 3 is a second anode active material layer.
Detailed Description
The preparation method of the present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention. All techniques implemented based on the above description of the invention are intended to be included within the scope of the invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the examples described below are commercially available unless otherwise specified.
In the description of the present invention, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not indicative or implying relative importance.
SnS-MoS used in the following examples 2 The material is prepared by the following method:
SiO modified with sulfonic acid group 2 The nanospheres are dispersed in a matrix containing Na 2 MoO 4 、Na 2 SnO 3 And CH (CH) 3 CSNH 2 Reaction of (2)In solution (Na) 2 MoO 4 :Na 2 SnO 3 :CH 3 CSNH 2 SiO modified with sulfonic acid group 2 The mass ratio of the nanospheres is 1:1:2:1.2), carrying out hydrothermal reaction for 12h at 200 ℃, washing and drying a hydrothermal product, and removing SiO through an etching process 2 Nanospheres, snS-MoS with interlayer covalent assembly structure is prepared 2 。
Example 1
(1) In particle size Dv 1 50 Negative electrode slurry 1 was prepared with 15 μm artificial graphite as a first negative electrode active material: mixing artificial graphite, a conductive agent SP and a binder SBR according to the mass ratio of 96.8:1.2:2, dispersing in water, and uniformly stirring to prepare negative electrode slurry 1, wherein the viscosity of the slurry is 2000-5000 mPas, and the solid content is 40-50wt%.
(2) In particle size Dv 2 50 300nm SnS-MoS 2 The material was used as a second negative electrode active material to prepare a negative electrode slurry 2: snS-MoS 2 Mixing the conductive agent SP and the binder SBR according to the mass ratio of 96.8:1.2:2, dispersing in water, and uniformly stirring to prepare the negative electrode slurry 2, wherein the viscosity of the slurry is 2000-5000 mPa.s, and the solid content is 40-50 wt%.
(3) And (3) coating the anode slurry prepared by the steps (1) and (2) on an anode current collector at the same time, wherein the anode slurry 2 is borne on the anode slurry 1, the anode slurry 1 is borne on the anode current collector, and coating work on two sides of the anode current collector is finished in the same way. The total thickness of one side of the negative electrode sheet after coating, drying and rolling was 55 μm, wherein the thickness of the first negative electrode active material layer was 50 μm and the thickness of the second negative electrode active material layer was 5 μm.
(4) Mixing an anode active material (lithium cobaltate), a conductive agent (conductive carbon black) and a binder (PVDF) according to a mass ratio of 96:2.5:1.5, dispersing in N-methyl pyrrolidone (NMP), uniformly stirring to prepare slurry, uniformly coating the slurry on the surfaces of two sides of an anode current collector aluminum foil, and baking at 100-150 ℃ for 4-8 hours to prepare an anode plate.
(5) Rolling, die cutting and cutting the positive and negative electrode sheets, winding and assembling to form a winding core, packaging with an aluminum plastic film after short circuit test is qualified, baking in an oven to remove water until the water content reaches the water content standard required by liquid injection, injecting electrolyte, aging for 24-48h, and completing primary charging by a hot-press formation process to obtain the activated lithium ion battery.
Examples 2 to 11
Other operations were the same as example 1 except that the first anode active material and the second anode active material were different in particle diameter and/or the first anode active material layer and the second anode active material layer were different in thickness, as shown in table 1.
Comparative example 1
(1) In particle size Dv 1 50 Negative electrode slurry 1 was prepared with 15 μm artificial graphite as a first negative electrode active material: mixing artificial graphite, a conductive agent SP and a binder SBR according to the mass ratio of 96.8:1.2:2, dispersing in water, and uniformly stirring to prepare negative electrode slurry 1, wherein the viscosity of the slurry is 2000-5000 mPas, and the solid content is 40-50wt%.
(2) The negative electrode slurry prepared in the above (1) was coated on a negative electrode current collector, wherein the negative electrode slurry 1 was carried on the negative electrode current collector, and the coating work of both sides of the negative electrode current collector was completed in the same manner. The negative electrode sheet after being coated, dried, and rolled had a total thickness of 55 μm on one side, that is, the thickness of the first negative electrode active material layer was 55 μm.
(3) Positive electrode active material (lithium cobaltate), conductive agent (conductive carbon black) and binder (PVDF) according to the mass ratio of 96.5%:2.5%:1.5% of the aluminum foil is mixed, dispersed in N-methyl pyrrolidone (NMP), uniformly stirred to prepare slurry, uniformly coated on the two side surfaces of the aluminum foil of the positive electrode current collector, and baked for 4-8 hours at 100-150 ℃ to prepare the positive electrode plate.
(4) Rolling, die cutting and cutting the positive and negative electrode sheets, winding and assembling to form a winding core, packaging with an aluminum plastic film after short circuit test is qualified, baking in an oven to remove water until the water content reaches the water content standard required by liquid injection, injecting electrolyte, aging for 24-48h, and completing primary charging by a hot-press formation process to obtain the activated lithium ion battery.
Comparative examples 2 to 3
Other operations were the same as comparative example 1 except that the first negative electrode active material was different in particle diameter, as shown in table 1.
Comparative example 4
(1) In particle size Dv 2 50 300nm SnS-MoS 2 The material was used as a second negative electrode active material to prepare a negative electrode slurry 2: snS-MoS 2 Mixing the conductive agent SP and the binder SBR according to the mass ratio of 96.8:1.2:2, dispersing in water, and uniformly stirring to prepare the negative electrode slurry 2, wherein the viscosity of the slurry is 2000-5000 mPa.s, and the solid content is 40-50 wt%.
(2) The negative electrode slurry prepared by (1) above was coated on both side surfaces of a negative electrode current collector. The negative electrode sheet after being coated, dried, and rolled had a total thickness of 55 μm on one side, that is, the thickness of the second negative electrode active material layer was 55 μm.
(3) Positive electrode active material (lithium cobaltate), conductive agent (conductive carbon black) and binder (PVDF) according to the mass ratio of 96.5%:2.5%:1.5% of the aluminum foil is mixed, dispersed in N-methyl pyrrolidone (NMP), uniformly stirred to prepare slurry, uniformly coated on the two side surfaces of the aluminum foil of the positive electrode current collector, and baked for 4-8 hours at 100-150 ℃ to prepare the positive electrode plate.
(4) Rolling, die cutting and cutting the positive and negative electrode sheets, winding and assembling to form a winding core, packaging with an aluminum plastic film after short circuit test is qualified, baking in an oven to remove water until the water content reaches the water content standard required by liquid injection, injecting electrolyte, aging for 24-48h, and completing primary charging by a hot-press formation process to obtain the activated lithium ion battery.
Performance test:
the lithium ion batteries prepared in the above examples and comparative examples were fully charged at 0.5C, and the ratio of the energy E discharged at 0.5C to the volume V of the lithium ion battery was the energy density ED in Wh.L -1 。
The lithium ion batteries prepared in the above examples and comparative examples were charged at 3C rate, and the capacity retention rate test was performed by cycling for 700 weeks with 1C rate discharge, and the lithium ion batteries after 700 times of charge and discharge were dissected to check the swelling and crushing conditions of the negative electrode active material in the negative electrode sheet.
The lithium ion batteries prepared in the examples and the comparative examples were charged at 5C rate, and after cycling for 20 weeks at 0.5C rate, the lithium ion batteries were dissected to see the lithium evolution condition.
Table 1 composition and performance test results of lithium ion batteries of examples and comparative examples
As can be seen from table 1, the lithium ion batteries prepared by the invention solve the problems of lithium precipitation, cycle capacity retention rate and energy density improvement of the lithium ion batteries compared with the lithium ion batteries of comparative examples 1 to 3; compared with the lithium ion battery of comparative example 4, the energy density of the lithium ion battery is obviously improved on the premise of ensuring no lithium precipitation.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A negative electrode sheet including a negative electrode current collector, a first negative electrode active material layer, and a second negative electrode active material layer; the first negative electrode active material layer is arranged on the first surface of the negative electrode current collector, and the second negative electrode active material layer is arranged on the surface of the first negative electrode active material layer;
the first anode active material layer comprises a first anode active material, the second anode active material layer comprises a second anode active material, the first anode active material is selected from graphite, and the second anode active material is selected from SnS-MoS 2 The method comprises the steps of carrying out a first treatment on the surface of the Thickness L of the first negative electrode active material layer 1 And a thickness L of the second anode active material layer 2 The ratio of (2) is as follows: l is more than or equal to 0.05 2 /L 1 ≤0.15；
The first negative electrode active material has a median particle diameter Dv 1 50 And the median particle diameter Dv of the second anode active material 2 50 The ratio of (2) is as follows: dv is 8 to or less 1 50 /Dv 2 50 ≤200。
2. The negative electrode sheet of claim 1, wherein the SnS-MoS 2 Is formed by covalently connecting MoS with SnS nano-dots 2 The nanoplatelets are made with hollow structures covalently assembled between layers.
3. The negative electrode sheet according to claim 2, wherein the SnS-MoS 2 Wherein the mass percentage of SnS is 20-50 wt%.
4. The negative electrode sheet according to claim 1, wherein the first negative electrode active material has a median particle diameter Dv 1 50 The method meets the following conditions: dv is less than or equal to 1 mu m 1 50 ≤50μm；
And/or, the second anode active material has a median particle diameter Dv 2 50 The method meets the following conditions: dv of 100nm or less 2 50 ≤600nm。
5. The negative electrode sheet according to claim 1, wherein the thickness L of the first negative electrode active material layer 1 10-200 mu m.
6. The negative electrode sheet according to any one of claims 1 to 5, wherein the first negative electrode active material layer is further provided on a second surface of the negative electrode current collector opposite to the first surface, and the second negative electrode active material layer is provided on the first negative electrode active material layer surface.
7. The negative electrode sheet according to any one of claims 1 to 5, wherein the first negative electrode active material layer further comprises a first conductive agent and a first binder;
and/or, the second anode active material layer further includes a second conductive agent and a second binder.
8. The negative electrode sheet according to any one of claims 1 to 5, wherein the first negative electrode active material layer includes the following components in mass fraction: 90 to 99.2wt% of a first negative active material, 0.2 to 4wt% of a first conductive agent, and 0.6 to 6wt% of a first binder;
and/or, the second anode active material layer comprises the following components in percentage by mass: 90 to 99.2wt% of a second negative active material, 0.2 to 4wt% of a second conductive agent, and 0.6 to 6wt% of a second binder.
9. A lithium ion battery comprising the negative electrode sheet of any one of claims 1-8.
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| CN104821240A (en) * | 2015-04-29 | 2015-08-05 | 岭南师范学院 | A kind of one-step hydrothermal synthesis method of SnS2/MoS2 composite material and its application |
| CN108807878A (en) * | 2018-05-07 | 2018-11-13 | 同济大学 | A method of preparing molybdenum disulfide/vulcanization tin composite material of hollow structure |
| CN113410432A (en) * | 2020-05-08 | 2021-09-17 | 珠海冠宇电池股份有限公司 | Negative plate, preparation method and lithium ion battery comprising negative plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104821240A (en) * | 2015-04-29 | 2015-08-05 | 岭南师范学院 | A kind of one-step hydrothermal synthesis method of SnS2/MoS2 composite material and its application |
| CN108807878A (en) * | 2018-05-07 | 2018-11-13 | 同济大学 | A method of preparing molybdenum disulfide/vulcanization tin composite material of hollow structure |
| CN113410432A (en) * | 2020-05-08 | 2021-09-17 | 珠海冠宇电池股份有限公司 | Negative plate, preparation method and lithium ion battery comprising negative plate |
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