CN114256501A - Negative plate and lithium ion battery containing same - Google Patents
Negative plate and lithium ion battery containing same Download PDFInfo
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- CN114256501A CN114256501A CN202111555182.5A CN202111555182A CN114256501A CN 114256501 A CN114256501 A CN 114256501A CN 202111555182 A CN202111555182 A CN 202111555182A CN 114256501 A CN114256501 A CN 114256501A
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 40
- 239000011871 silicon-based negative electrode active material Substances 0.000 claims abstract description 21
- 239000002346 layers by function Substances 0.000 claims abstract description 11
- 239000007773 negative electrode material Substances 0.000 claims description 88
- 239000010410 layer Substances 0.000 claims description 78
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 31
- 239000010703 silicon Substances 0.000 claims description 31
- 229910052710 silicon Inorganic materials 0.000 claims description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 20
- 239000006183 anode active material Substances 0.000 claims description 20
- 239000011866 silicon-based anode active material Substances 0.000 claims description 15
- 239000011230 binding agent Substances 0.000 claims description 10
- 229910052799 carbon Inorganic materials 0.000 claims description 10
- 239000006258 conductive agent Substances 0.000 claims description 9
- 239000002994 raw material Substances 0.000 claims description 5
- 239000011856 silicon-based particle Substances 0.000 claims description 4
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 3
- 229910021385 hard carbon Inorganic materials 0.000 claims description 3
- 229910021382 natural graphite Inorganic materials 0.000 claims description 3
- 229910021384 soft carbon Inorganic materials 0.000 claims description 3
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 21
- 229910052744 lithium Inorganic materials 0.000 abstract description 21
- 230000001351 cycling effect Effects 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 18
- 238000000034 method Methods 0.000 description 10
- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 238000002156 mixing Methods 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- 239000007774 positive electrode material Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000011149 active material Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 230000008961 swelling Effects 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000002174 Styrene-butadiene Substances 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 239000004816 latex Substances 0.000 description 2
- 229920000126 latex Polymers 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000011115 styrene butadiene Substances 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 230000010261 cell growth Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007572 expansion measurement Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000011239 graphite-silicon composite material Substances 0.000 description 1
- 229910003474 graphite-silicon composite material Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 239000002931 mesocarbon microbead Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a negative plate and a lithium ion battery containing the same, wherein the negative plate comprises a negative current collector and a functional layer positioned on the surface of at least one side of the negative current collector; the functional layer comprises a silicon-based negative electrode active material, and the particle size Dn50 of the silicon-based negative electrode active material is gradually increased from the surface close to the negative electrode current collector to the outside. The cathode plate is applied to the lithium battery, so that the expansion phenomenon of the silicon-doped cathode plate of the lithium battery can be well inhibited, and the comprehensive performances of the battery, such as cycling stability, safety and the like, are improved.
Description
Technical Field
The invention relates to the field of lithium batteries, in particular to a negative plate and a lithium ion battery containing the same.
Background
The lithium ion battery has the advantages of high working voltage, high energy density, long cycle life, environmental friendliness and the like, and is widely applied to the fields of 3C digital products, electric automobiles, military aerospace and the like. Along with the popularization and application of intelligent digital products and the wide application of new energy automobiles, the requirements for shortening the charging time of the lithium ion battery and improving the energy density of the lithium ion battery become more urgent, and further higher requirements are provided for the charging speed and the charging voltage of the lithium ion battery.
At present, the common application of lithium ion batteries in power and electronic equipment also increasingly raises the demand of lithium ion batteries. However, as a carbon material mainly used for the current anode, the capacity thereof has been raised to the limit. In the research of new anode materials, silicon materials are considered as the next-generation anode materials having the most promising commercial application prospect and are widely researched. Many companies have also introduced silicon oxygen, silicon carbon negative electrode materials with comparable performance.
Graphite doped silicon cathode materials are currently an effective way to increase energy density. However, with the increase of energy density, the silicon negative electrode material expands greatly, so that the further application of the silicon negative electrode material in the lithium ion battery is limited. Therefore, in the current application, the energy density is mainly improved by mixing a small amount of graphite. Especially when the silicon negative electrode is applied to negative electrode plates on soft package and square-shell batteries, the silicon negative electrode expansion is a main challenge faced by the blended silicon negative electrode batteries.
Therefore, how to optimize the structural design of the lithium battery negative plate to better inhibit the negative expansion, so that the lithium battery negative plate can adapt to the application environment of the soft package battery and has a longer service life is an important problem to be solved by the technical staff in the field.
Disclosure of Invention
In order to improve the technical problem, the invention provides a silicon-doped negative plate of a lithium battery, which can better inhibit the expansion phenomenon of the negative electrode of the lithium battery while improving the energy density.
In order to achieve the purpose, the invention adopts the following technical scheme:
the negative plate comprises a negative current collector and a functional layer positioned on at least one side surface of the negative current collector;
the functional layer comprises a silicon-based negative electrode active material, and the particle size Dn50 of the silicon-based negative electrode active material is gradually increased from the surface close to the negative electrode current collector to the outside.
In the present invention, D1、D2All calculated as Dn 50. Dn50 is also called median diameter or median diameter, and refers to the average particle diameter of the powder particles. The Dn50 index refers to the particle size corresponding to a cumulative percentage of the particle size distribution in a sample of 50%.
According to the present invention, the particle size Dn50 of the silicon-based anode active material may be between 3 μm and 20 μm.
According to the present invention, the functional layer includes a first negative electrode active material layer and a second negative electrode active material layer, the first negative electrode active material layer being located between a negative electrode current collector and the second negative electrode active material layer;
the first negative electrode active material layer comprises a first silicon-based negative electrode active material;
the second negative electrode active material layer comprises a second silicon-based negative electrode active material;
the particle size Dn50 of the second silicon-based anode active material is greater than the particle size Dn50 of the first silicon-based anode active material.
Research shows that when the rebounded pole piece is rolled, the paste coating compaction of the upper layer (far away from the current collector) is smaller than that of the lower layer (the current collector side); because the size change of lithium intercalation/deintercalation of the large-particle-size silicon-based negative electrode active material is larger, the research mixes the silicon-based negative electrode active material with smaller particle size in a region (a second negative electrode active material layer) with a bottom layer compacted close to a current collector through the design of the silicon-doped negative electrode piece. The upper layer is far away from the current collector to compact a smaller area (the first negative electrode active material layer), and silicon-based negative electrode active materials with larger particle sizes are blended to relieve the expansion of the silicon-based negative electrode active materials in the pole piece.
According to the invention, the particle size distribution of the silicon-based negative active material in the negative active materials in the first negative active material layer and the second negative active material layer is controlled, the pole piece structure of the negative electrode is changed, the negative pole piece with continuous active material coating and segmented mechanical strength performance is provided, the volume expansion of silicon in the negative pole piece in the slow-release circulation process is used, the battery cell expansion is further reduced, and the problem of the expansion of the negative pole piece in the circulation process of applying the silicon negative electrode to the soft package lithium ion battery at present is solved.
According to the study of the present invention, the particle diameter Dn50 (D) of the first silicon-based anode active material1) And a particle diameter Dn50 (D) of the second silicon-based anode active material2) Ratio D of2/D1Is 1.2-2, and is exemplified by 1.2, 1.5, 1.8 and 2. By mixing the particle size Dn50 (D) of the first silicon-based anode active material1) And a particle diameter Dn50 (D) of the second silicon-based anode active material2) Ratio D of2/D1The volume expansion of the negative electrode can be well reduced by controlling the volume expansion to be 1.2-2.
For example, the particle diameter Dn50 (D) of the second silicon-based anode active material2) 7 to 10 μm, the particle diameter Dn50 (D) of the first silicon-based anode active material1) 5 μm to 7 μm, and D1<D2。
For the pole piece section, the above pole piece characteristics can be observed by counting the particle size distribution under a scanning electron microscope.
For the pole piece, the active material (first negative electrode active material layer) near the current collector side, and the active material (second negative electrode active material layer) of the pole piece surface layer were scraped. Graphite, binder, etc. are eliminated by heat treatment. And for the residual silicon cathode, respectively characterizing by a laser particle size distribution instrument. By comparison, the particle diameter D of the second silicon-based anode active material can be found2And a particle diameter D of the second silicon-based negative electrode active material1，D2/D1The ratio is 1.2-2.
According to the present invention, the raw material of the first anode active material layer includes: 70-99 wt% of a first negative electrode active material, 0.5-15 wt% of a conductive agent and 0.5-15 wt% of a binder; the first negative electrode active material includes a first silicon-based negative electrode active material.
According to the present invention, the raw material of the second anode active material layer includes: 70-99 wt% of a second negative electrode active material, 0.5-15 wt% of a conductive agent and 0.5-15 wt% of a binder; the second anode active material includes a second silicon-based anode active material.
According to the present invention, the mass percentage of the conductive agent and the binder in the second anode active material layer may be greater than the mass percentage of the conductive agent and the binder in the first anode active material layer.
According to the present invention, the first anode active material further includes a carbon-based anode active material.
According to the present invention, the second anode active material further includes a carbon-based anode active material.
According to the invention, in the first negative electrode active material layer and the second negative electrode active material layer, the particle diameters of the carbon-based negative electrode active materials are the same or different, and independently can be between 3 μm and 20 μm, and there is no clear requirement on the particle diameter distribution of the carbon-based negative electrode active materials in the pole piece.
According to the invention, in the first and second negative electrode active material layers, the first and second silicon-based negative electrode active materials are used in the same amount or different amounts, and independently of each other, the amounts of the first and second silicon-based negative electrode active materials may be 5 to 15%, illustratively 5%, 10%, 15% of the total mass of the first and second negative electrode active materials.
According to the present invention, the silicon-based negative active material is, for example, at least one of silicon particles, silicon oxide, silicon carbon, and the like. Preferably silicon particles.
According to the present invention, the carbon-based negative active material is, for example, at least one of natural graphite, artificial graphite, hard carbon, and soft carbon.
According to the invention, functional layers are oppositely arranged on the two side surfaces of the negative current collector.
The invention also provides a preparation method of the negative plate, which comprises the following steps: the method comprises the steps of sequentially coating first negative electrode active material layer slurry and second negative electrode active material layer slurry on at least one side surface of a negative electrode current collector to form a first negative electrode active material layer and a second negative electrode active material layer, wherein the first negative electrode active material layer and the second negative electrode active material layer form a functional layer of a lithium battery negative plate. Wherein solid contents of the slurry forming the first anode active material layer and the slurry forming the second anode active material layer may be 40 wt% to 45 wt%.
According to the invention, the two side surfaces of the negative electrode current collector are coated with the second negative electrode active material layer and the first negative electrode active material layer in sequence, and the first negative electrode active material layer and the second negative electrode active material layer form the functional layer of the negative electrode piece of the lithium battery.
The method can be used for reducing the expansion of the pole piece when the silicon negative electrode is used to a certain extent except for the particle size and the silicon negative electrode with different expansion rates.
In the present invention, the carbon-based negative active material of the first negative active material and the second negative active material may also be at least one of artificial graphite, natural graphite, mesocarbon microbeads, soft carbon, hard carbon, and the like; the silicon-based negative electrode active material can also be at least one of a silicon-based material, a graphite-silicon composite material, lithium titanate and the like. In specific implementation, the negative electrode active material can be screened by testing the lithium intercalation expansion rate of the negative electrode active material, and then the negative electrode active material having the target expansion rate is selected. For example, the first negative electrode active material is graphite and the second negative electrode active material may be silicon, but the second negative electrode active material is silicon having different expansion rates.
The invention also provides application of the negative plate in a lithium ion battery.
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.
Preferably, the positive plate comprises a positive current collector and a positive active layer coated on one or both surfaces of the positive current collector.
Preferably, the positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder;
according to one example of the invention, the mixing mass ratio of the positive electrode active material, the conductive agent and the binder is (93-98): (1-4): 1-3); exemplary 97.2:1.5: 1.3.
According to the present invention, the positive electrode active material is at least one selected from lithium cobaltate, lithium nickel cobalt manganese oxide, lithium iron phosphate, and the like.
According to the present invention, the conductive agent in the positive electrode active material layer is selected from at least one of acetylene black, carbon nanotubes, and the like.
According to the present invention, the binder in the positive electrode active material layer is selected from polyvinylidene fluoride.
The invention has the beneficial effects that:
the lithium battery negative plate provided by the invention has lower expansion rate, and can better inhibit the expansion phenomenon of the lithium battery and improve the comprehensive properties of the battery, such as cycle stability, safety and the like, when being applied to the lithium battery; the expansion rate of the assembled lithium battery is less than 2% of that of a conventional pole piece with the same blending proportion after the lithium battery is cycled for 300 times.
The winding type battery cell comprising the lithium battery negative plate and the lithium ion battery comprising the winding type battery cell have better capacity of inhibiting expansion of the lithium battery, safety and cycling stability.
Drawings
Fig. 1 is a schematic view of a negative electrode sheet active material composite layer according to an embodiment of the invention;
fig. 2 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the invention; in the figure: 201. a negative current collector; 203. a first negative electrode active material layer; 204. a second anode active material layer;
FIG. 3 is a schematic structural diagram of a positive plate according to an embodiment of the present invention; in the figure: 301. a positive current collector; 302. a positive electrode active material layer.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.
Example 1
Preparing a negative plate: respectively preparing slurry for forming a first negative electrode active material layer and slurry for forming a second negative electrode active material layer; wherein:
the slurry composition of the first anode active material layer was: 97 wt% (90% graphite + 10% silicon), 1 wt% conductive carbon black and 2 wt% styrene-butadiene latex, wherein the solid content is 40-45 wt%;
the slurry composition of the second anode active material layer was: 97 wt% (90% graphite + 10% silicon), 1 wt% conductive carbon black and 2 wt% styrene-butadiene latex, wherein the solid content is 40-45 wt%;
the particle diameter Dn50 (denoted as D1) of silicon in the first negative electrode active material in the slurry for forming the first negative electrode active material layer and the particle diameter Dn50 (denoted as D2) of silicon in the second negative electrode active material in the slurry for forming the second negative electrode active material layer are shown in table 1.
The first negative electrode active material layer and the second negative electrode active material layer were formed by sequentially coating the slurry of the second negative electrode active material layer and the slurry of the second negative electrode active material layer on both side surfaces of the negative electrode current collector, and the negative electrode sheet was obtained by drying and rolling, and had a structure shown in fig. 2, in which the thickness of the first negative electrode active material layer (H1) and the thickness of the second negative electrode active material layer (H2) are shown in table 1.
Preparing a positive plate: adding lithium cobaltate, acetylene black and polyvinylidene fluoride into a stirring tank according to the mass ratio of 97.2:1.5:1.3, adding an N-methyl pyrrolidone solvent, stirring, and then sieving with a 200-mesh sieve to prepare anode active material layer slurry with the solid content of 70-75 wt%; coating the slurry on a positive current collector (aluminum foil) by using a coating machine, drying at 120 ℃, and rolling to obtain a positive plate, wherein the structure of the positive plate is shown in figure 3.
Assembling the battery cell: and (3) winding the prepared negative plate, the positive plate and the polyolefin porous membrane (diaphragm) together to form a winding core (the width is 62mm), packaging by using an aluminum plastic membrane, baking to remove moisture, injecting an electrolyte, and performing hot pressing to obtain the battery core.
Examples 2 to 4 and comparative example 1
Examples 2-4 and comparative example 1 were prepared according to the same procedure as example 1, except that: the particle diameter Dn50 (denoted as D1) of silicon in the first negative electrode active material in the slurry for forming the first negative electrode active material layer and the particle diameter Dn50 (denoted as D2) of silicon in the second negative electrode active material in the slurry for forming the second negative electrode active material layer are shown in table 1.
The first negative electrode active material layer and the second negative electrode active material layer were formed by sequentially coating the slurry of the first negative electrode active material layer and the slurry of the second negative electrode active material layer on the negative electrode current collector, and the negative electrode sheet was obtained by drying and rolling, and had a structure shown in fig. 2, in which the thickness of the first negative electrode active material layer (H1) and the thickness of the second negative electrode active material layer (H2) are shown in table 1.
For the cyclic expansion measurement of the cell: and (4) carrying out normal charge and discharge circulation on the battery cell, and obtaining the circulation expansion data of the battery cell according to the data of the test process every 50T. (25 +/-5) DEG C, and specifically, testing the voltage, the internal resistance and the direct current internal resistance of the incoming sample state by the following steps:
1. standing at 25 + -2 deg.C for 10 min;
2. discharging to lower limit voltage at 0.2C, and standing for 10 min;
3. charging to the upper limit voltage (without constant voltage) at 0.5C, and testing first full-current data (voltage, internal resistance and direct-current internal resistance);
4. standing at 25 deg.C for 10 min;
5. discharging to lower limit voltage at 0.5C, and standing for 10 min;
6. charging to the upper limit voltage at 0.5 deg.C (without constant voltage), and standing for 10 min;
7. step 4-6, circulating 1000 times, and testing process data (thickness) of full electricity every 50 times; after the cycle, the data (thickness) in the full charge state were measured.
TABLE 1
The cells obtained in examples 1 to 4 and comparative example 1 were assembled into a lithium ion battery, and the capacity retention rate after 300 cycles was tested and the cell swelling phenomenon was observed under 1C charging and 0.7C discharging conditions, and the test results are shown in table 2.
TABLE 2
| Number of cycles | Capacity retention rate | Expansion rate of cell | |
| Example 1 | 300T | 90.2％ | 8.0％ |
| Example 2 | 300T | 92.2％ | 11.0％ |
| Example 3 | 300T | 90.1％ | 9.0％ |
| Example 4 | 300T | 90.2％ | 10.0％ |
| Comparative example 1 | 300T | 95.3％ | 6.0％ |
As can be seen from the test results of table 2,
comparing examples 2, 4 with comparative example 1: after the silicon is doped, the expansion of the battery cell is larger in the circulation process;
comparing example 2 with example 4, the swelling was greater for blending large particle size silicon (Dn50 ═ 9 μm) compared to blending small particle silicon (Dn50 ═ 6 μm);
comparing example 3 with example 1, the same thickness of the pole piece and the amount of silicon blended, as a two-layer coating, the swelling of the pole piece surface large particle silicon (Dn50 ═ 9 μm) + collector side small particle silicon (Dn50 ═ 6 μm) was smaller.
In conclusion, under the condition of the same blending proportion and the same thickness of the pole piece, the design of the pole piece with the minimum expansion can be realized by adjusting the distribution of the particle size of the blended silicon in the pole piece layer under the condition of ensuring unchanged compaction; meanwhile, large-particle-size silicon is mixed with the upper layer with richer gaps, so that the expansion of silicon particles in the circulation process is relieved, and smaller expansion is shown on the layer surface of the pole piece. Therefore, the circulation stability of the battery cell is more facilitated. Compared with the conventional single-layer pole piece design, the expansion of the battery cell is reduced by 2 percent or more.
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, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The negative plate is characterized by comprising a negative current collector and a functional layer positioned on at least one side surface of the negative current collector;
the functional layer comprises a silicon-based negative electrode active material, and the particle size Dn50 of the silicon-based negative electrode active material is gradually increased from the surface close to the negative electrode current collector to the outside.
2. The negative electrode sheet according to claim 1, wherein the functional layer comprises a first negative electrode active material layer and a second negative electrode active material layer, the first negative electrode active material layer being located between a negative electrode current collector and the second negative electrode active material layer;
the first negative electrode active material layer comprises a first silicon-based negative electrode active material;
the second negative electrode active material layer comprises a second silicon-based negative electrode active material;
the particle size Dn50 of the second silicon-based anode active material is greater than the particle size Dn50 of the first silicon-based anode active material.
3. The negative electrode sheet of claim 2, wherein the particle size Dn50 (D) of the first silicon-based negative active material1) And a particle diameter Dn50 (D) of the second silicon-based anode active material2) Ratio D of2/D1Is 1.2 to 2.
4. The negative electrode sheet of claim 2, wherein the raw material of the first negative electrode active material layer comprises: 70-99 wt% of a first negative electrode active material, 0.5-15 wt% of a conductive agent and 0.5-15 wt% of a binder; the first negative electrode active material includes a first silicon-based negative electrode active material.
5. The negative electrode sheet of claim 2, wherein the raw material of the second negative electrode active material layer comprises: 70-99 wt% of a second negative electrode active material, 0.5-15 wt% of a conductive agent and 0.5-15 wt% of a binder; the second anode active material includes a second silicon-based anode active material.
6. The negative electrode sheet of claim 4 or 5, wherein the first negative electrode active material further comprises a carbon-based negative electrode active material;
the second anode active material further includes a carbon-based anode active material;
in the first and second anode active material layers, the carbon-based anode active materials may have the same or different particle diameters, and may be 3 to 20 μm independently of each other.
7. The negative electrode sheet according to claim 6, wherein the first and second negative electrode active materials are used in the same or different amounts, and independently from each other, the amounts of the first and second silicon-based negative electrode active materials may be 5 to 15% by mass of the total mass of the negative electrode active material layers.
8. The negative electrode sheet of claim 6, wherein the silicon-based negative active material is at least one of silicon particles, silicon oxygen, and silicon carbon.
9. The negative electrode sheet of claim 6, wherein the carbon-based negative active material is at least one of natural graphite, artificial graphite, hard carbon, and soft carbon.
10. A lithium ion battery comprising the negative electrode sheet according to any one of claims 1 to 9.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114899360A (en) * | 2022-04-29 | 2022-08-12 | 江苏正力新能电池技术有限公司 | Silicon-based negative electrode plate, secondary battery and power utilization device |
| CN115692604A (en) * | 2022-11-23 | 2023-02-03 | 江苏正力新能电池技术有限公司 | Positive plate, preparation method thereof and battery |
| WO2023225937A1 (en) * | 2022-05-26 | 2023-11-30 | 宁德时代新能源科技股份有限公司 | Negative electrode plate and preparation method therefor, secondary battery, battery module, battery pack and electric device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160285101A1 (en) * | 2015-03-25 | 2016-09-29 | Kabushiki Kaisha Toshiba | Electrode for nonaqueous electrolyte battery, nonaqueous electrolyte battery and battery pack |
| CN111052456A (en) * | 2017-10-16 | 2020-04-21 | 株式会社Lg化学 | Negative electrode for lithium secondary battery and lithium secondary battery including the same |
| CN111261834A (en) * | 2020-03-25 | 2020-06-09 | 宁德新能源科技有限公司 | Negative electrode sheet, electrochemical device, and electronic device |
| CN111384374A (en) * | 2018-12-29 | 2020-07-07 | 宁德时代新能源科技股份有限公司 | Negative active material, negative pole piece and battery |
| CN112018328A (en) * | 2020-09-21 | 2020-12-01 | 珠海冠宇电池股份有限公司 | Silicon-doped negative plate and lithium ion battery comprising same |
| CN113764619A (en) * | 2021-10-12 | 2021-12-07 | 厦门海辰新能源科技有限公司 | Pole piece and pole piece assembly |
-
2021
- 2021-12-17 CN CN202111555182.5A patent/CN114256501A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160285101A1 (en) * | 2015-03-25 | 2016-09-29 | Kabushiki Kaisha Toshiba | Electrode for nonaqueous electrolyte battery, nonaqueous electrolyte battery and battery pack |
| CN111052456A (en) * | 2017-10-16 | 2020-04-21 | 株式会社Lg化学 | Negative electrode for lithium secondary battery and lithium secondary battery including the same |
| CN111384374A (en) * | 2018-12-29 | 2020-07-07 | 宁德时代新能源科技股份有限公司 | Negative active material, negative pole piece and battery |
| CN111261834A (en) * | 2020-03-25 | 2020-06-09 | 宁德新能源科技有限公司 | Negative electrode sheet, electrochemical device, and electronic device |
| CN112018328A (en) * | 2020-09-21 | 2020-12-01 | 珠海冠宇电池股份有限公司 | Silicon-doped negative plate and lithium ion battery comprising same |
| CN113764619A (en) * | 2021-10-12 | 2021-12-07 | 厦门海辰新能源科技有限公司 | Pole piece and pole piece assembly |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114899360A (en) * | 2022-04-29 | 2022-08-12 | 江苏正力新能电池技术有限公司 | Silicon-based negative electrode plate, secondary battery and power utilization device |
| WO2023225937A1 (en) * | 2022-05-26 | 2023-11-30 | 宁德时代新能源科技股份有限公司 | Negative electrode plate and preparation method therefor, secondary battery, battery module, battery pack and electric device |
| CN115692604A (en) * | 2022-11-23 | 2023-02-03 | 江苏正力新能电池技术有限公司 | Positive plate, preparation method thereof and battery |
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