CN118676298A - Lithium battery negative electrode plate and preparation method and application thereof - Google Patents
Lithium battery negative electrode plate and preparation method and application thereof Download PDFInfo
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- CN118676298A CN118676298A CN202310699269.2A CN202310699269A CN118676298A CN 118676298 A CN118676298 A CN 118676298A CN 202310699269 A CN202310699269 A CN 202310699269A CN 118676298 A CN118676298 A CN 118676298A
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- negative electrode
- active material
- electrode active
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 81
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 80
- 238000002360 preparation method Methods 0.000 title abstract description 15
- 239000007773 negative electrode material Substances 0.000 claims abstract description 187
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- 239000004584 polyacrylic acid Substances 0.000 claims abstract description 4
- 239000002002 slurry Substances 0.000 claims description 97
- 238000000576 coating method Methods 0.000 claims description 16
- 239000011248 coating agent Substances 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
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- 239000006183 anode active material Substances 0.000 claims 3
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 43
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- 239000010439 graphite Substances 0.000 description 28
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- 230000000052 comparative effect Effects 0.000 description 8
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 6
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
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- 238000004519 manufacturing process Methods 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
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- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
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- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 229910006095 SO2F Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
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- 239000007769 metal material Substances 0.000 description 2
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- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 description 1
- BJWMSGRKJIOCNR-UHFFFAOYSA-N 4-ethenyl-1,3-dioxolan-2-one Chemical compound C=CC1COC(=O)O1 BJWMSGRKJIOCNR-UHFFFAOYSA-N 0.000 description 1
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- 229910013188 LiBOB Inorganic materials 0.000 description 1
- 229910010941 LiFSI Inorganic materials 0.000 description 1
- 229910010584 LiFeO2 Inorganic materials 0.000 description 1
- 229910052493 LiFePO4 Inorganic materials 0.000 description 1
- 229910002993 LiMnO2 Inorganic materials 0.000 description 1
- 229910013131 LiN Inorganic materials 0.000 description 1
- 229910013716 LiNi Inorganic materials 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 1
- 229910002097 Lithium manganese(III,IV) oxide Inorganic materials 0.000 description 1
- 229910016289 MxO2 Inorganic materials 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
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- 229910000676 Si alloy Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
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- 239000006233 lamp black Substances 0.000 description 1
- 229910001540 lithium hexafluoroarsenate(V) Inorganic materials 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 1
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 1
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- 150000002739 metals Chemical class 0.000 description 1
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- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 1
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- 229910052718 tin Inorganic materials 0.000 description 1
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- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of 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
- H01M4/36—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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
本发明提出了锂电池负极极片及其制备方法与应用，所述锂电池负极极片包括：集流体；以及负极活性物质层，至少设置在所述集流体的一侧；其中，所述负极活性物质层包括第一负极活性物质层和第二负极活性物质层，所述第一负极活性物质层设置在所述集流体上，所述第二负极活性物质层设置在所述第一负极活性物质层远离所述集流体的一侧，所述第一负极活性物质层和所述第二负极活性物质层包括第一粘结剂，所述第一粘结剂包括聚丙烯酸，且所述第一粘结剂在所述第一负极活性物质层或所述第二负极活性物质层中的含量为1.2wt％‑1.3wt％。通过发明提出的锂电池负极极片及其制备方法与应用，同时提高锂电池的动力学性能和循环性能。
The present invention proposes a lithium battery negative electrode plate and a preparation method and application thereof, wherein the lithium battery negative electrode plate comprises: a current collector; and a negative electrode active material layer, at least arranged on one side of the current collector; wherein the negative electrode active material layer comprises 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 current collector, the second negative electrode active material layer is arranged on the side of the first negative electrode active material layer away from the current collector, the first negative electrode active material layer and the second negative electrode active material layer comprise a first binder, the first binder comprises polyacrylic acid, and the content of the first binder in the first negative electrode active material layer or the second negative electrode active material layer is 1.2wt%-1.3wt%. Through the lithium battery negative electrode plate and the preparation method and application thereof proposed by the invention, the dynamic performance and cycle performance of the lithium battery are improved at the same time.
Description
技术领域Technical Field
本发明涉及锂电池技术领域，具体涉及锂电池负极极片及其制备方法与应用。The present invention relates to the technical field of lithium batteries, and in particular to a negative electrode sheet of a lithium battery and a preparation method and application thereof.
背景技术Background Art
锂电池作为一种新型的高能电池在性能上的提高仍有很大的空间，而负极活性材料性能的提高是其中的关键。负极活性材料应具备容量大、充放电循环性能良好、放电电压平稳、不可逆容量损失小以及对电解液稳定等性能。石墨负极活性材料储量大、成本低以及安全无毒等优点，成为主流负极活性材料。As a new type of high-energy battery, lithium battery still has a lot of room for improvement in performance, and the key is to improve the performance of negative electrode active materials. Negative electrode active materials should have large capacity, good charge and discharge cycle performance, stable discharge voltage, small irreversible capacity loss, and stability to electrolyte. Graphite negative electrode active materials have the advantages of large reserves, low cost, safety and non-toxicity, and have become the mainstream negative electrode active materials.
锂电池的发展要满足快充性能且循环较好，目前单一的石墨作为负极活性材料，无法同时满足高动力学、高充放电效率和高循环性能等要求。The development of lithium batteries must meet the requirements of fast charging performance and good cycle performance. Currently, single graphite as the negative electrode active material cannot simultaneously meet the requirements of high dynamics, high charge and discharge efficiency and high cycle performance.
发明内容Summary of the invention
本发明提出的锂电池负极极片及其制备方法与应用，能够保证了锂电池负极极片的容量性能，提高锂电池负极极片的均匀性和一致性，同时满足锂电池的高动力学和长循环性能。The lithium battery negative electrode sheet and its preparation method and application proposed in the present invention can ensure the capacity performance of the lithium battery negative electrode sheet, improve the uniformity and consistency of the lithium battery negative electrode sheet, and at the same time meet the high dynamics and long cycle performance of the lithium battery.
为解决上述技术问题，本发明是通过如下的技术方案实现的。To solve the above technical problems, the present invention is implemented through the following technical solutions.
本发明提出一种锂电池负极极片，至少包括：The present invention provides a lithium battery negative electrode plate, comprising at least:
集流体；以及a current collector; and
负极活性物质层，至少设置在所述集流体的一侧；A negative electrode active material layer, disposed at least on one side of the current collector;
其中，所述负极活性物质层包括第一负极活性物质层和第二负极活性物质层，所述第一负极活性物质层设置在所述集流体上，所述第二负极活性物质层设置在所述第一负极活性物质层远离所述集流体的一侧，所述第一负极活性物质层和所述第二负极活性物质层包括第一粘结剂，所述第一粘结剂包括聚丙烯酸，且所述第一粘结剂在所述第一负极活性物质层或所述第二负极活性物质层中的含量为1.2wt％-1.3wt％。Among them, the negative electrode active material layer includes 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 current collector, and the second negative electrode active material layer is arranged on the side of the first negative electrode active material layer away from the current collector, the first negative electrode active material layer and the second negative electrode active material layer include a first binder, the first binder includes polyacrylic acid, and the content of the first binder in the first negative electrode active material layer or the second negative electrode active material layer is 1.2wt%-1.3wt%.
在本发明一实施例中，所述第一负极活性物质层包括第一负极活性材料，所述第一负极活性材料的Dv50为13μm-17μm；In one embodiment of the present invention, the first negative electrode active material layer includes a first negative electrode active material, and the Dv50 of the first negative electrode active material is 13 μm-17 μm;
其中，Dv50表示所述第一负极活性材料在体积基准的粒度分布中，50％的颗粒粒径小于该值。Herein, Dv50 indicates that in the volume-based particle size distribution of the first negative electrode active material, 50% of the particles have a particle size smaller than this value.
在本发明一实施例中，所述第二负极活性物质层包括第二负极活性物质层，且所述第一负极活性材料和所述第二负极活性材料的Dv50的差值为0-7μm。In one embodiment of the present invention, the second negative electrode active material layer includes a second negative electrode active material layer, and the difference in Dv50 between the first negative electrode active material and the second negative electrode active material is 0-7 μm.
在本发明一实施例中，所述第一负极活性材料的克容量小于所述第二负极活性材料的克容量。In one embodiment of the present invention, the gram capacity of the first negative electrode active material is less than the gram capacity of the second negative electrode active material.
在本发明一实施例中，所述负极活性物质层的总厚度为140μm-280μm。In one embodiment of the present invention, the total thickness of the negative electrode active material layer is 140 μm-280 μm.
在本发明一实施例中，所述第一负极活性物质层的厚度和所述第二负极活性物质层的厚度之比为ε，且满足0.62≤ε≤1.32。In one embodiment of the present invention, a ratio of a thickness of the first negative electrode active material layer to a thickness of the second negative electrode active material layer is ε, and satisfies 0.62≤ε≤1.32.
在本发明一实施例中，所述第一负极活性物质层和所述第二负极活性物质层包括第二粘结剂，所述第二粘结剂包括甲基纤维素类粘结剂，所述第二粘结剂在所述第一负极活性物质层或所述第二负极活性物质层中的含量为0.4wt％-0.5wt％。In one embodiment of the present invention, the first negative electrode active material layer and the second negative electrode active material layer include a second binder, the second binder includes a methyl cellulose binder, and the content of the second binder in the first negative electrode active material layer or the second negative electrode active material layer is 0.4wt%-0.5wt%.
在本发明一实施例中，所述第一负极活性物质层和所述第二负极活性物质层包括第三粘结剂，所述第三粘结剂包括丁苯橡胶粘结剂，所述第三粘结剂在所述第一负极活性物质层或所述第二负极活性物质层中的含量为0.4wt％-0.5wt％。In one embodiment of the present invention, the first negative electrode active material layer and the second negative electrode active material layer include a third binder, the third binder includes styrene-butadiene rubber binder, and the content of the third binder in the first negative electrode active material layer or the second negative electrode active material layer is 0.4wt%-0.5wt%.
本发明还提供一种锂电池负极极片的制备方法，至少包括以下步骤：The present invention also provides a method for preparing a negative electrode sheet of a lithium battery, which comprises at least the following steps:
提供一集流体；providing a fluid collector;
配制第一浆料和第二浆料；Prepare a first slurry and a second slurry;
在所述集流体至少一侧涂覆所述第一浆料，形成第一浆料层，并进行干燥；Coating the first slurry on at least one side of the current collector to form a first slurry layer, and drying the first slurry layer;
在干燥后的所述第一浆料层上涂覆所述第二浆料，形成第二浆料层；coating the second slurry on the dried first slurry layer to form a second slurry layer;
对所述第一浆料层和第二浆料层进行烘干、辊压和剪切，形成锂电池负极极片。The first slurry layer and the second slurry layer are dried, rolled and sheared to form a negative electrode sheet for a lithium battery.
在本发明一实施例中，所述第一浆料的粘度为4800-7000mPa·s，固含量为54wt％-57wt％。In one embodiment of the present invention, the viscosity of the first slurry is 4800-7000 mPa·s, and the solid content is 54 wt%-57 wt%.
在本发明一实施例中，所述第二浆料的粘度为5000-8000mPa·s，固含量为54wt％-57wt％。In one embodiment of the present invention, the viscosity of the second slurry is 5000-8000 mPa·s, and the solid content is 54 wt%-57 wt%.
本发明还提供一种电化学装置，包括上述所述的锂电池负极极片。The present invention also provides an electrochemical device, comprising the above-mentioned negative electrode plate of the lithium battery.
综上所述，本发明提出的锂电池负极极片及其制备方法与应用，不同负极活性材料形成的负极活性物质层，能够保证锂电池的容量和循环性能，同时保证锂电池的快充/快放和高低温性能，从而确保锂电池具备良好的高低温性能和循环稳定性。提高负极活性物质的含量，进一步保证了锂电池负极极片的容量性能。能够提高锂电池负极极片的均匀性和一致性，提高锂电池的性能。提高负极活性物质层的厚度，以提高锂电池的容量。多层负极活性物质层选择不同性能的负极活性材料，锂电池能同时满足高动力学和长循环性能。In summary, the negative electrode sheet of a lithium battery proposed in the present invention, its preparation method and application, and the negative electrode active material layer formed by different negative electrode active materials can ensure the capacity and cycle performance of the lithium battery, while ensuring the fast charge/fast discharge and high and low temperature performance of the lithium battery, thereby ensuring that the lithium battery has good high and low temperature performance and cycle stability. Increasing the content of the negative electrode active material further ensures the capacity performance of the negative electrode sheet of the lithium battery. It is possible to improve the uniformity and consistency of the negative electrode sheet of the lithium battery and improve the performance of the lithium battery. Increase the thickness of the negative electrode active material layer to increase the capacity of the lithium battery. The multi-layer negative electrode active material layer selects negative electrode active materials with different properties, and the lithium battery can simultaneously meet high dynamics and long cycle performance.
当然，实施本发明的任一方式并不一定需要同时达到以上所述的所有优点。Of course, any method of implementing the present invention does not necessarily need to achieve all of the advantages mentioned above at the same time.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
为了更清楚地说明本发明实施例的技术方案，下面将对实施例描述所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.
图1为本发明一实施例锂电池负极极片的结构示意图。FIG. 1 is a schematic structural diagram of a negative electrode plate of a lithium battery according to an embodiment of the present invention.
图2为本发明另一实施例锂电池负极极片的结构示意图。FIG. 2 is a schematic diagram of the structure of a negative electrode plate of a lithium battery according to another embodiment of the present invention.
图3为本发明一实施例锂电池的结构示意图。FIG. 3 is a schematic structural diagram of a lithium battery according to an embodiment of the present invention.
具体实施方式DETAILED DESCRIPTION
以下通过特定的具体实例说明本发明的实施方式，本领域技术人员可由本说明书所揭露的内容轻易地了解本发明的其他优点与功效。本发明还可以通过另外不同的具体实施方式加以实施或应用，本说明书中的各项细节也可以基于不同观点与应用，在没有背离本发明的精神下进行各种修饰或改变。The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
应当理解的是，本发明能够以不同形式实施，而不应当解释为局限于这里提出的实施例。相反地，提供这些实施例将使公开彻底和完全，并且将本发明的范围完全地传递给本领域技术人员。此外，如出现术语“第一”、“第二”仅用于描述和区分目的，而不能理解为指示或暗示相对重要性。It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In addition, the terms "first" and "second" are used only for description and distinction purposes, and should not be understood as indicating or suggesting relative importance.
下面结合若干实施例及附图对本发明的技术方案做进一步详细说明，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。The technical solution of the present invention is further described in detail below in conjunction with several embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
锂电池具有高比能量、无记忆效应和循环寿命长等优点，已经逐渐应用于多个领域。锂电池包括正极、负极、电解液和隔膜，其中，负极是电池在充电过程中，是锂离子和电子的载体，起着能量的储存与释放的作用，主要影响锂电池的首次效率、循环性能和倍率(快充)等。本发明提供的锂电池负极极片及其制备方法与应用，能够兼具高动力学和长循环性能，提高锂电池的性能。Lithium batteries have the advantages of high specific energy, no memory effect and long cycle life, and have been gradually applied in many fields. Lithium batteries include positive electrodes, negative electrodes, electrolytes and separators. Among them, the negative electrode is the carrier of lithium ions and electrons during the charging process of the battery, plays the role of energy storage and release, and mainly affects the initial efficiency, cycle performance and rate (fast charging) of lithium batteries. The lithium battery negative electrode plate provided by the present invention and its preparation method and application can have both high dynamics and long cycle performance, and improve the performance of lithium batteries.
请参阅图1至图2所示，在本发明一实施例中，提供一种锂电池负极极片，负极极片包括集流体10和负极活性物质层20，负极活性物质层20至少设置在集流体10的一侧。其中，负极活性物质层20包括第一负极活性物质层21和第二负极活性物质层22，第一负极活性物质层21设置在集流体10上，第二负极活性物质层22设置在第一负极活性物质层21远离集流体10的一侧。其中，第一负极活性物质层21包括第一负极活性材料，第二负极活性物质层22包括第二负极活性材料，第一负极活性材料和第二负极活性材料的粒径、比表面积以及克容量等不同。且第一负极活性物质层21和第二负极活性物质层22中包括多种粘结剂，降低粘结剂的总含量，提高负极极片的容量性能，并提高负极活性物质层的界面性能，同时满足高动力学和长循环性能。Referring to FIG. 1 and FIG. 2, in one embodiment of the present invention, a negative electrode plate of a lithium battery is provided, the negative electrode plate comprises a current collector 10 and a negative electrode active material layer 20, and the negative electrode active material layer 20 is arranged on at least one side of the current collector 10. The negative electrode active material layer 20 comprises a first negative electrode active material layer 21 and a second negative electrode active material layer 22, the first negative electrode active material layer 21 is arranged on the current collector 10, and the second negative electrode active material layer 22 is arranged on the side of the first negative electrode active material layer 21 away from the current collector 10. The first negative electrode active material layer 21 comprises a first negative electrode active material, and the second negative electrode active material layer 22 comprises a second negative electrode active material, and the first negative electrode active material and the second negative electrode active material have different particle sizes, specific surface areas, and gram capacities. The first negative electrode active material layer 21 and the second negative electrode active material layer 22 comprise a plurality of binders, which reduces the total content of the binder, improves the capacity performance of the negative electrode plate, and improves the interface performance of the negative electrode active material layer, while meeting high kinetics and long cycle performance.
请参阅图1至图2所示，在本发明一实施例中负极活性物质层20的总厚度例如为140μm-280μm，第一负极活性物质层21的厚度和第二负极活性物质层22的厚度之比记为ε，且满足0.62≤ε≤1.32。在本实施例中，负极活性物质层20例如设置在集流体10的两侧，且第一负极活性物质层21在集流体10两侧的厚度相同，第二负极活性物质层22在集流体10两侧的厚度相同。在其他实施例中，根据制作要求，第一负极活性物质层21和/或第二负极活性物质层22在集流体10两侧的厚度也可以不相同。Please refer to FIG. 1 and FIG. 2 . In one embodiment of the present invention, the total thickness of the negative electrode active material layer 20 is, for example, 140 μm-280 μm, and the ratio of the thickness of the first negative electrode active material layer 21 to the thickness of the second negative electrode active material layer 22 is denoted as ε, and satisfies 0.62≤ε≤1.32. In this embodiment, the negative electrode active material layer 20 is, for example, disposed on both sides of the current collector 10, and the thickness of the first negative electrode active material layer 21 on both sides of the current collector 10 is the same, and the thickness of the second negative electrode active material layer 22 on both sides of the current collector 10 is the same. In other embodiments, according to manufacturing requirements, the thickness of the first negative electrode active material layer 21 and/or the second negative electrode active material layer 22 on both sides of the current collector 10 may also be different.
请参阅图1至图2所示，在本发明一实施例中，集流体10例如为铜箔集流体、复合铜箔集流体、碳集流体、泡沫铜集流体或不锈钢集流体等，且集流体10的厚度例如为8μm-12μm。在集流体10的表面上设置负极活性物质层20，且负极活性物质层20至少设置在集流体10的一侧，即可以在集流体10的两面设置负极活性物质层20，也可以在集流体10的一侧设置负极活性物质层20，具体可根据制作要求进行选择。Referring to FIG. 1 and FIG. 2 , in one embodiment of the present invention, the current collector 10 is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector or a stainless steel current collector, and the thickness of the current collector 10 is, for example, 8 μm-12 μm. A negative electrode active material layer 20 is disposed on the surface of the current collector 10, and the negative electrode active material layer 20 is disposed on at least one side of the current collector 10, that is, the negative electrode active material layer 20 can be disposed on both sides of the current collector 10, or on one side of the current collector 10, and the specific selection can be made according to the production requirements.
请参阅图1至图2所示，在本发明一实施例中，第一负极活性物质层21包括第一负极活性材料，第二负极活性物质层22包括第二负极活性材料。其中，负极活性材料是可使锂嵌入、脱嵌的材料，包括但不限于结晶碳(天然石墨及人造石墨等)、无定形碳、碳涂层石墨及树脂涂层石墨等碳材料，也可以为氧化铟、氧化硅、氧化锡、钛酸锂、氧化锌、氧化锂等氧化物材料，也可以为锂金属或者可与锂形成合金的金属材料。其中，可以为与锂形成合金的金属材料，例如为Cu、Sn、Si、Co、Mn、Fe、Sb及Ag等，也可以使用含有这些金属与锂的二元或三元的合金作为负极活性物质。这些负极活性物质可以单独使用，也可以两种及以上组合使用。从高能量密度化的角度出发，也可将石墨等碳材料与Si、Si合金或Si氧化物等Si系材料组合使用。Please refer to FIG. 1 to FIG. 2 . In one embodiment of the present invention, the first negative electrode active material layer 21 includes a first negative electrode active material, and the second negative electrode active material layer 22 includes a second negative electrode active material. Among them, the negative electrode active material is a material that can embed and de-embed lithium, including but not limited to carbon materials such as crystalline carbon (natural graphite and artificial graphite, etc.), amorphous carbon, carbon-coated graphite and resin-coated graphite, and can also be an oxide material such as indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide, lithium oxide, etc., and can also be lithium metal or a metal material that can form an alloy with lithium. Among them, it can be a metal material that forms an alloy with lithium, such as Cu, Sn, Si, Co, Mn, Fe, Sb and Ag, etc., and a binary or ternary alloy containing these metals and lithium can also be used as a negative electrode active material. These negative electrode active materials can be used alone or in combination of two or more. From the perspective of high energy density, carbon materials such as graphite can also be used in combination with Si, Si alloys or Si oxides and other Si-based materials.
请参阅图1至图2所示，在本发明一实施例中，第一负极活性材料例如包括第一石墨，第二负极活性材料例如包括第二石墨，第一石墨和第二石墨的性能参数如表1所示。在本实施例中，第一石墨例如由石油焦制备的人工石墨，且第一石墨的Dv50例如为13μm-17μm，第一石墨的比表面积(Special Surface Area，SSA)例如为1.38m2/g，堆密度(TapDensity，TD)例如为1.08g/cc，克容量例如为348mAh/g，首次效率例如为93.1％，即第一石墨为高能比石墨，其中，Dv50表示负极活性材料在体积基准的粒度分布中，50％的颗粒粒径小于该值。第二石墨例如由针状焦制备的人工石墨，且第二石墨的Dv50例如为10μm-13μm，第二石墨的比表面积(Special Surface Area，SSA)例如为1.02m2/g，堆密度(TapDensity，TD)例如为1.08g/cc，克容量例如为355mAh/g，首次效率例如为93.4％，即第二石墨为高动力学石墨。第一负极活性材料的Dv50与第二负极活性材料的Dv50的差值例如为0-7μm，即第二负极活性材料的粒度小于或等于第一负极活性材料的粒度，且第一负极活性材料的克容量小于第二负极活性材料的克容量。通过在集流体上设置包括不同负极活性材料的负极活性物质层，靠近集流体的第一负极活性材料能够保证锂电池的容量和循环性能，远离集流体的第二负极活性材料能够保证锂电池的快充/快放和高低温性能，从而确保锂电池具备良好的低温性能和循环稳定性。Please refer to FIG. 1 and FIG. 2 . In one embodiment of the present invention, the first negative electrode active material includes, for example, a first graphite, and the second negative electrode active material includes, for example, a second graphite. The performance parameters of the first graphite and the second graphite are shown in Table 1. In this embodiment, the first graphite is, for example, artificial graphite prepared from petroleum coke, and the Dv50 of the first graphite is, for example, 13 μm-17 μm, the specific surface area (Special Surface Area, SSA) of the first graphite is, for example, 1.38 m 2 /g, the tap density (Tap Density, TD) is, for example, 1.08 g/cc, the gram capacity is, for example, 348 mAh/g, and the first efficiency is, for example, 93.1%, that is, the first graphite is a high energy specific graphite, wherein Dv50 indicates that in the volume-based particle size distribution of the negative electrode active material, 50% of the particle sizes are smaller than this value. The second graphite is, for example, artificial graphite prepared from needle coke, and the Dv50 of the second graphite is, for example, 10 μm-13 μm, the specific surface area (Special Surface Area, SSA) of the second graphite is, for example, 1.02 m 2 /g, the tap density (TapDensity, TD) is, for example, 1.08 g/cc, the gram capacity is, for example, 355 mAh/g, and the first efficiency is, for example, 93.4%, that is, the second graphite is high-kinetic graphite. The difference between the Dv50 of the first negative electrode active material and the Dv50 of the second negative electrode active material is, for example, 0-7 μm, that is, the particle size of the second negative electrode active material is less than or equal to the particle size of the first negative electrode active material, and the gram capacity of the first negative electrode active material is less than the gram capacity of the second negative electrode active material. By arranging a negative electrode active material layer including different negative electrode active materials on the current collector, the first negative electrode active material close to the current collector can ensure the capacity and cycle performance of the lithium battery, and the second negative electrode active material far away from the current collector can ensure the fast charge/fast discharge and high and low temperature performance of the lithium battery, thereby ensuring that the lithium battery has good low temperature performance and cycle stability.
表1、第一石墨和第二石墨的性能参数Table 1. Performance parameters of the first graphite and the second graphite
请参阅图1至图2所示，在本发明一实施例中，第一负极活性物质层21和第二负极活性物质层22包括多种粘结剂，具体例如包括第一粘结剂、第二粘结剂和第三粘结剂等。其中，第一粘结剂例如包括聚丙烯酸(Polyacrylic Acid，PAA)粘结剂，且第一粘结在第一负极活性物质层21或第二负极活性物质层22的含量例如为1.2wt％-1.3wt％。第二粘结剂例如包括羧甲基纤维素(Carboxymethyl Cellulose，CMC)类粘结剂，具体例如为羧甲基纤维素钠或其他羧甲基纤维素盐等，且第二粘结在第一负极活性物质层21或第二负极活性物质层22中的含量例如为0.4wt％-0.5wt％。第三粘结剂例如包括丁苯橡胶(PolymerizedStyrene Butadiene Rubbe，SBR)粘结剂，且第三粘结在第一负极活性物质层21和第二负极活性物质层22中的含量例如为0.4wt％-0.5wt％。通过粘结剂的混用，且第一粘结剂是面类结构粘结剂，粘结性能好，在水系溶剂润湿性好且膨胀系数小，第一粘结剂可以降低浆料中第二粘结剂的用量，提高负极活性材料的含量，进一步保证了负极极片的容量性能。Referring to FIG. 1 and FIG. 2 , in one embodiment of the present invention, the first negative electrode active material layer 21 and the second negative electrode active material layer 22 include a plurality of binders, specifically, for example, a first binder, a second binder, and a third binder. The first binder, for example, includes a polyacrylic acid (PAA) binder, and the content of the first binder in the first negative electrode active material layer 21 or the second negative electrode active material layer 22 is, for example, 1.2wt%-1.3wt%. The second binder, for example, includes a carboxymethyl cellulose (CMC) binder, specifically, for example, sodium carboxymethyl cellulose or other carboxymethyl cellulose salts, and the content of the second binder in the first negative electrode active material layer 21 or the second negative electrode active material layer 22 is, for example, 0.4wt%-0.5wt%. The third binder, for example, includes a styrene butadiene rubber (SBR) binder, and the content of the third binder in the first negative electrode active material layer 21 and the second negative electrode active material layer 22 is, for example, 0.4wt%-0.5wt%. By mixing the binders, and the first binder being a surface structure binder with good bonding properties, good wettability in aqueous solvents and a small expansion coefficient, the first binder can reduce the amount of the second binder in the slurry, increase the content of the negative electrode active material, and further ensure the capacity performance of the negative electrode sheet.
本发明还提供一种锂电池负极极片的制备方法，制备方法至少包括步骤S11-S15。The present invention also provides a method for preparing a negative electrode plate of a lithium battery, and the preparation method at least includes steps S11-S15.
步骤S11、提供一集流体，并对集流体进行清洗和烘干。Step S11, providing a current collector, and cleaning and drying the current collector.
步骤S12、配制第一浆料和第二浆料。Step S12, preparing a first slurry and a second slurry.
步骤S13、在集流体上涂覆第一浆料，形成第一浆料层，并进行干燥。Step S13: coating the first slurry on the current collector to form a first slurry layer, and drying the layer.
步骤S14、在干燥后的第一浆料层上涂覆第二浆料，形成第二浆料层。Step S14: coating the second slurry on the dried first slurry layer to form a second slurry layer.
步骤S15、对第一浆料层和第二浆料层进行烘干、辊压和剪切，形成负极极片。Step S15: drying, rolling and shearing the first slurry layer and the second slurry layer to form a negative electrode sheet.
在本发明一实施例中，在步骤S11中，依据制作要求选择集流体的种类，并对集流体进行处理。在本实施例中，先将集流体依次使用无水乙醇、丙酮及去离子水在超声清洗仪里进行清洗，以去除集流体上的油污，再例如在真空干燥箱中进行干燥，且干燥温度例如为60℃-80℃，干燥时间例如为20min-30min。通过对集流体的处理，以减少集流体上的污染物对电池性能的影响。In one embodiment of the present invention, in step S11, the type of current collector is selected according to the manufacturing requirements, and the current collector is processed. In this embodiment, the current collector is first cleaned in an ultrasonic cleaner using anhydrous ethanol, acetone and deionized water in sequence to remove oil stains on the current collector, and then dried in a vacuum drying oven, for example, and the drying temperature is, for example, 60°C-80°C, and the drying time is, for example, 20min-30min. By processing the current collector, the influence of pollutants on the current collector on the battery performance is reduced.
在本发明一实施例中，在步骤S12中，在配制第一浆料时，将制备所需的第一粘结剂、第一负极活性材料和导电剂进行预拌干混。混合均匀后，例如加入第一浆料中总溶剂量的30wt％-50wt％的溶剂，高速分散例如25min-35min后，加入第二粘结剂，继续高速分散例如80min-100min。继续加入第一浆料中总溶剂量的50wt％-70wt％的溶剂，调节第一浆料中的固含量例如为54wt％-57wt％时，加入第三粘结剂，低速分散例如25min-35min后，进行消泡处理，获得第一浆料。In one embodiment of the present invention, in step S12, when preparing the first slurry, the first binder, the first negative electrode active material and the conductive agent required for preparation are pre-mixed and dry-mixed. After uniform mixing, for example, 30wt%-50wt% of the total solvent amount in the first slurry is added, and after high-speed dispersion for example 25min-35min, the second binder is added, and high-speed dispersion for example 80min-100min is continued. 50wt%-70wt% of the total solvent amount in the first slurry is continued to be added. When the solid content in the first slurry is adjusted to, for example, 54wt%-57wt%, the third binder is added, and after low-speed dispersion for example 25min-35min, a defoaming treatment is performed to obtain the first slurry.
在本发明一实施例中，在步骤S12中，在配制第二浆料时，将制备所需的第一粘结剂、第二负极活性材料和导电剂进行预拌干混。混合均匀后，例如加入第二浆料中总溶剂量的30wt％-50wt％的溶剂，高速分散例如25min-35min后，加入第二粘结剂，继续高速分散例如80min-100min。继续加入第二浆料中总溶剂量的50wt％-70wt％的溶剂，调节第二浆料中的固含量例如为54wt％-57wt％时，加入第三粘结剂，低速分散例如25min-35min后，进行消泡处理，获得第二浆料。In one embodiment of the present invention, in step S12, when preparing the second slurry, the first binder, the second negative electrode active material and the conductive agent required for preparation are pre-mixed and dry-mixed. After uniform mixing, for example, 30wt%-50wt% of the total solvent amount in the second slurry is added, and after high-speed dispersion for example 25min-35min, the second binder is added, and high-speed dispersion for example 80min-100min is continued. 50wt%-70wt% of the total solvent amount in the second slurry is continued to be added. When the solid content in the second slurry is adjusted to, for example, 54wt%-57wt%, the third binder is added, and after low-speed dispersion for example 25min-35min, a defoaming treatment is performed to obtain the second slurry.
在本发明一实施例中，在步骤S12中，导电剂例如为导电炭黑(Super P，SP)、乙炔黑、碳纳米管(Carbon Nanotube，CNT)和石墨烯等中任意一种或多种，在本实施例中，导电剂例如为导电炭黑。在第一浆料或第二浆料中，除溶剂外的物质，以100％计，导电剂的含量例如为0.42wt％-0.60wt％，第一粘结的含量例如为1.2wt％-1.3wt％，第二粘结剂的含量例如为0.4wt％-0.5wt％，第三粘结剂的含量例如为0.4wt％-0.5wt％。In one embodiment of the present invention, in step S12, the conductive agent is, for example, any one or more of conductive carbon black (Super P, SP), acetylene black, carbon nanotube (Carbon Nanotube, CNT) and graphene, etc. In this embodiment, the conductive agent is, for example, conductive carbon black. In the first slurry or the second slurry, the content of the substance other than the solvent is 100%, and the content of the conductive agent is, for example, 0.42wt%-0.60wt%, the content of the first binder is, for example, 1.2wt%-1.3wt%, the content of the second binder is, for example, 0.4wt%-0.5wt%, and the content of the third binder is, for example, 0.4wt%-0.5wt%.
在本发明一实施例中，在步骤S12中，第一负极活性材料例如为第一石墨，在第一浆料中，除溶剂外的物质，以100％计，第一负极活性材料的含量例如97.2wt％-97.5wt％。第二负极活性材料例如为第二石墨，在第二浆料中，除溶剂外的物质，以100％计，第二负极活性材料的含量例如97.2wt％-97.5wt％。In one embodiment of the present invention, in step S12, the first negative electrode active material is, for example, a first graphite, and in the first slurry, the content of the first negative electrode active material is, for example, 97.2wt%-97.5wt%, based on 100% of the substances other than the solvent. The second negative electrode active material is, for example, a second graphite, and in the second slurry, the content of the second negative electrode active material is, for example, 97.2wt%-97.5wt%, based on 100% of the substances other than the solvent.
在本发明一实施例中，在步骤S12中，第一浆料和第二浆料中的溶剂例如为去离子水，第一浆料和第二浆料例如在磁力搅拌器或真空搅拌机上进行分散。在其他实施例中，溶剂可根据制作要求进行选择，分散方式和分散速度可根据生产进行调整。在第一浆料和第二浆料中，除负极活性材料外，浆料的配方相同，能够提高第一负极活性物质层和第二负极活性物质的层接触面处石墨颗粒排列一致性，以避免上下层由于粘结力不同造成的石墨滑移现象，保证负极极片中石墨有序排列。即第一浆料和第二浆料通过采用相同配方制备负极极片，能够提高负极极片的均匀性和一致性，能够提高锂电池的性能。In one embodiment of the present invention, in step S12, the solvent in the first slurry and the second slurry is, for example, deionized water, and the first slurry and the second slurry are dispersed, for example, on a magnetic stirrer or a vacuum stirrer. In other embodiments, the solvent can be selected according to the production requirements, and the dispersion method and dispersion speed can be adjusted according to production. In the first slurry and the second slurry, except for the negative electrode active material, the slurry formula is the same, which can improve the consistency of the arrangement of graphite particles at the contact surface of the first negative electrode active material layer and the second negative electrode active material layer, so as to avoid the graphite slip phenomenon caused by the different bonding forces between the upper and lower layers, and ensure the orderly arrangement of graphite in the negative electrode sheet. That is, the first slurry and the second slurry can improve the uniformity and consistency of the negative electrode sheet by using the same formula to prepare the negative electrode sheet, and can improve the performance of the lithium battery.
在本发明一实施例中，在步骤S13中，在涂覆第一浆料和第二浆料之前，可以在步骤S11处理好的集流体上涂覆其他涂层，也可以直接涂覆第一浆料，具体根据锂电池的制作要求进行选择，本发明不做具体限制。其中，第一浆料例如通过刮刀涂布、辊涂或狭缝挤压涂布等方式进行单层涂布，具体例如通过涂布磨头进行单层涂布。其中，第一浆料中的固含量例如为54wt％-57wt％，第一浆料的出货粘度例如为4800mPa·s-7000mPa·s，第一浆料出货的最大细度小于或等于35μm。在集流的一侧或两侧形成第一浆料层，对第一浆料层进行干燥处理，例如在真空干燥机或加热箱等设备中进行干燥处理。In one embodiment of the present invention, in step S13, before applying the first slurry and the second slurry, other coatings may be applied on the current collector treated in step S11, or the first slurry may be directly applied. The specific selection is based on the production requirements of the lithium battery, and the present invention does not impose specific restrictions. Among them, the first slurry is applied in a single layer by, for example, blade coating, roller coating, or slit extrusion coating, and specifically, for example, by a coating grinding head. Among them, the solid content in the first slurry is, for example, 54wt%-57wt%, the delivery viscosity of the first slurry is, for example, 4800mPa·s-7000mPa·s, and the maximum fineness of the first slurry delivery is less than or equal to 35μm. A first slurry layer is formed on one or both sides of the current collector, and the first slurry layer is dried, for example, in a vacuum dryer or a heating box.
在本发明一实施例中，在步骤S14中，在第一浆料层干燥后，在第一浆料层上涂覆第二浆料，且第二浆料例如通过刮刀涂布、辊涂或狭缝挤压涂布等方式进行单层涂布，具体例如通过涂布磨头进行单层涂布，即在集流体上进行单模头双层涂布。其中，第二浆料中的固含量例如为54wt％-57wt％，第二浆料的出货粘度例如为5000mPa·s-8000mPa·s，第二浆料出货的最大细度小于或等于35μm。在一侧或两侧的第一浆料层上形成第二浆料层。In one embodiment of the present invention, in step S14, after the first slurry layer is dried, the second slurry is coated on the first slurry layer, and the second slurry is coated in a single layer by, for example, blade coating, roller coating or slit extrusion coating, specifically, by a coating grinding head, that is, a single-die double-layer coating is performed on the current collector. The solid content in the second slurry is, for example, 54wt%-57wt%, the delivery viscosity of the second slurry is, for example, 5000mPa·s-8000mPa·s, and the maximum fineness of the second slurry delivery is less than or equal to 35μm. The second slurry layer is formed on one or both sides of the first slurry layer.
在本发明一实施例中，在步骤S15中，在涂覆第二浆料后，对第一浆料层和第二浆料层进行烘干，例如在真空干燥机或加热箱等设备中进行烘干。在浆料层烘干后，对集流体进行辊压和剪切等，以形成负极极片，在辊压过程中，要考虑第一负极活性材料和/或第二负极活性材料的最高压实密度，避免压力过大造成的负极活性材料层出现裂纹或断裂等缺陷。在本实施例中，第一浆料层在经过干燥和辊压后，形成第一负极活性物质层，第二浆料层在经过干燥和辊压后，形成第二负极活性物质层。在本实施例中，例如在集流体的两侧均设置第一负极活性物质层和第二负极活性物质层，第一负极活性物质层和第二负极活性物质层的总厚度例如为140μm-280μm。通过双层涂布，提高负极活性物质层的厚度，以提高锂电池的容量。In one embodiment of the present invention, in step S15, after the second slurry is applied, the first slurry layer and the second slurry layer are dried, for example, in a vacuum dryer or a heating box. After the slurry layer is dried, the current collector is rolled and sheared to form a negative electrode sheet. During the rolling process, the highest compaction density of the first negative electrode active material and/or the second negative electrode active material should be considered to avoid defects such as cracks or fractures in the negative electrode active material layer caused by excessive pressure. In this embodiment, the first slurry layer forms a first negative electrode active material layer after drying and rolling, and the second slurry layer forms a second negative electrode active material layer after drying and rolling. In this embodiment, for example, the first negative electrode active material layer and the second negative electrode active material layer are arranged on both sides of the current collector, and the total thickness of the first negative electrode active material layer and the second negative electrode active material layer is, for example, 140μm-280μm. Through double-layer coating, the thickness of the negative electrode active material layer is increased to increase the capacity of the lithium battery.
请参阅图3所示，本发明还提供本发明还提出一种锂电池，包括负极极片100、正极极片200、隔膜300和电解液400，隔膜300位于负极极片100和正极极片200之间，负极极片100、正极极片200和隔膜300之间填充电解液400，且负极极片100为上述方法获得的负极极片。其中，锂电池例如为一次电池或二次电池，又例如为二次电池。且锂离子二次电池例如为软包电池、硬壳电池和圆柱电池等。Please refer to FIG3 , the present invention also provides a lithium battery, including a negative electrode sheet 100, a positive electrode sheet 200, a separator 300 and an electrolyte 400, wherein the separator 300 is located between the negative electrode sheet 100 and the positive electrode sheet 200, and the electrolyte 400 is filled between the negative electrode sheet 100, the positive electrode sheet 200 and the separator 300, and the negative electrode sheet 100 is the negative electrode sheet obtained by the above method. Among them, the lithium battery is, for example, a primary battery or a secondary battery, and for example, a secondary battery. And the lithium-ion secondary battery is, for example, a soft-pack battery, a hard-shell battery, a cylindrical battery, etc.
请参阅图3所示，在本发明一实施例中，正极极片200例如包括正极集流体、和设置在正极集流体上正极活性物质层。正极集流体例如为镍、钛、铝、镍、银、不锈钢或碳等进行表面处理后形成的箔材即可，正极集流体的表面光滑，也可在正极集流体表面形成细小的纹路等从而提高正极活性材料与正极集流体之间的粘附力。除了箔材以外，正极集流体还可以采用膜状、网状、多孔状、泡沫或无纺布等多种形式中的任意一种或多种组合使用。Please refer to FIG. 3 . In one embodiment of the present invention, the positive electrode plate 200 includes, for example, a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector. The positive electrode current collector may be, for example, a foil formed by surface treatment of nickel, titanium, aluminum, nickel, silver, stainless steel or carbon. The surface of the positive electrode current collector is smooth, and fine lines may be formed on the surface of the positive electrode current collector to improve the adhesion between the positive electrode active material and the positive electrode current collector. In addition to the foil, the positive electrode current collector may also be in the form of a film, a mesh, a porous form, a foam or a non-woven fabric, and any one or more combinations thereof.
在本发明一实施例中，正极活性物质层中包括正极活性材料，正极活性材料例如选择LiMnO2、LiFeO2、LiMn2O4、Li2FeSiO4、LiNi1/3Co1/3Mn1/3O2、LiNi5CO2Mn3O2、LiFePO4、LizNi(1-x-y)CoxMyO2、LiNiaCobMncMepO2及LimCo(1-n)MxO2等中的一种或几种混合。其中，在LizNi(1-x-y)CoxMyO2中，0.01≤x≤0.20、0≤y≤0.20、0.97≤z≤1.20，M选自Mn、V、Mg、Mo、Nb及Al中的至少一种元素。在LiNiaCobMncMepO2中，a+b+c＝1，0≤p≤0.1，Me选自Zr、Zn、Cu、Cr、Mg、Fe、V、Ti、Sr、Sb、Y、W、Nb或Al中的一种或多种的组合。在LimCo(1-n)MnO2中，0≤n≤0.1、0.97≤m≤1.20，M选自Mn、Ni、V、Mg、Mo、Nb及Al中的一种或多种的组合。In one embodiment of the present invention, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is selected from one or a mixture of LiMnO2, LiFeO2 , LiMn2O4 , Li2FeSiO4 , LiNi1 /3Co1 / 3Mn1 / 3O2 , LiNi5CO2Mn3O2, LiFePO4, LizNi(1-xy) CoxMyO2 , LiNiaCobMncMepO2 and LimCo (1-n) MxO2 . In LizNi ( 1 - xy ) CoxMyO2 , 0.01≤x≤0.20 , 0≤y≤0.20 , 0.97≤z≤1.20 , and M is selected from at least one element of Mn, V , Mg, Mo , Nb and Al. In LiNi a Co b Mn c Me p O 2 , a+b+c=1, 0≤p≤0.1, Me is selected from a combination of one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb or Al. In Li m Co (1-n) M n O 2 , 0≤n≤0.1, 0.97≤m≤1.20, M is selected from a combination of one or more of Mn, Ni, V, Mg, Mo, Nb and Al.
在本发明一实施例中，正极活性物质层中还包括粘接剂和导电剂等物质，添加量依照不同需求，可以在正极活性材料总量的1-50wt％中调整。导电剂例如选自天然石墨或人造石墨等石墨类材料，也可以选自炭黑、乙炔黑、科琴黑、槽法炭黑、炉黑、灯黑或热裂法炭黑等炭黑类材料，也可以选自碳纤维或金属纤维等导电纤维，也可以选自金属粉末如氟化碳粉末、铝粉末或镍粉末等金属粉末，也可以选自氧化锌或钛酸钾等导电晶须，也可以选自二氧化钛等导电金属氧化物或聚亚苯基衍生物，以用于保证电极具有良好的充放电性能的试剂。粘接剂例如选自聚偏二氟乙烯、聚乙烯醇、羧甲基纤维素、淀粉、羟丙基纤维素、再生纤维素、聚乙烯基吡咯烷酮、四氟乙烯、聚乙烯、聚丙烯、乙烯-丙烯-双烯三元共聚物(EPDM)、磺化的EPDM、丁苯橡胶或氟橡胶和各种共聚物等，以助于正极活性材料与导电剂之间的结合，并有助于正极活性材料与正极集流体结合。In one embodiment of the present invention, the positive electrode active material layer also includes materials such as a binder and a conductive agent, and the added amount can be adjusted within 1-50wt% of the total amount of the positive electrode active material according to different needs. The conductive agent is selected from, for example, graphite materials such as natural graphite or artificial graphite, or carbon black materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black, or conductive fibers such as carbon fibers or metal fibers, or metal powders such as carbon fluoride powder, aluminum powder or nickel powder, or conductive whiskers such as zinc oxide or potassium titanate, or conductive metal oxides such as titanium dioxide or polyphenylene derivatives, to ensure that the electrode has good charge and discharge performance. The binder is selected from, for example, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber or fluororubber and various copolymers, etc., to help the bonding between the positive electrode active material and the conductive agent, and to help the bonding between the positive electrode active material and the positive electrode current collector.
请参阅图3所示，在本发明一实施例中，正极活性材料例如选自LiNi0.8Co0.1Mn0.1O2，粘接剂例如选自聚偏二氟乙烯，导电剂例如选自乙炔黑，正极活性材料、粘结剂和导电剂例如按照质量比98:1:1混合，并加入适量的溶剂N-甲基吡咯烷酮(N-Methylpyrrolidone，NMP)，利用真空搅拌机搅拌至正极浆料呈均一透明状，获得正极浆料。将正极浆料均匀涂覆于例如16μm的铝箔集流体上，在室温下晾干后转移至烘箱，以例如80℃-120℃烘干例如6h，然后经过冷压、分切得到正极极片200。Please refer to FIG. 3 . In one embodiment of the present invention, the positive electrode active material is selected from LiNi 0.8 Co 0.1 Mn 0.1 O 2 , the binder is selected from polyvinylidene fluoride, the conductive agent is selected from acetylene black, the positive electrode active material, the binder and the conductive agent are mixed at a mass ratio of 98:1:1, and an appropriate amount of solvent N-methylpyrrolidone (NMP) is added, and the positive electrode slurry is stirred by a vacuum mixer until the positive electrode slurry is uniform and transparent to obtain the positive electrode slurry. The positive electrode slurry is evenly coated on a 16 μm aluminum foil current collector, dried at room temperature, and then transferred to an oven, dried at 80° C.-120° C. for 6 hours, and then cold pressed and cut to obtain the positive electrode sheet 200.
请参阅图3所示，在本发明一实施例中，隔膜300例如为聚乙烯膜(Polyethylene，PE)、聚丙烯膜(Polypropylene，PP)、玻璃纤维膜或聚乙烯膜等。其中，隔膜300的厚度例如为9μm-18μm，孔隙率例如为30％-50％，孔径为5μm-300μm，透气率为180s/100mL-380s/100mL。隔膜300具有高离子渗透率、高机械强度、耐化学性和疏水性，以确保负极极片100和正极极片200的之间绝缘。Please refer to FIG. 3 . In one embodiment of the present invention, the diaphragm 300 is, for example, a polyethylene film (PE), a polypropylene film (PP), a glass fiber film or a polyethylene film. The thickness of the diaphragm 300 is, for example, 9 μm-18 μm, the porosity is, for example, 30%-50%, the pore size is 5 μm-300 μm, and the air permeability is 180 s/100 mL-380 s/100 mL. The diaphragm 300 has high ion permeability, high mechanical strength, chemical resistance and hydrophobicity to ensure insulation between the negative electrode plate 100 and the positive electrode plate 200.
请参阅图3所示，在本发明一实施例中，电解液400例如包括有机溶剂、锂盐和添加剂等。有机溶剂例如选自碳酸二甲酯(Dimethyl Carbonate，DMC)、碳酸二乙酯(DiethylCarbonate，DEC)、碳酸二丙酯(Dipropyl Carbonate，DPC)、碳酸甲基丙酯(Methyl PropylCarbonate，MPC)、碳酸乙基丙酯(Ethylpropyl Carbonate，EPC)、碳酸甲基乙酯(MEC)、碳酸甲乙酯(Ethyl Methyl Carbonate，EMC)、碳酸亚乙酯(Ethylene Carbonate，EC)、碳酸亚丙酯(Propylene Carbonate，PC)和碳酸亚丁酯(Butylene Carbonate，BC)中的一种或多种。锂盐例如选自LiPF6、LiBF4、LiN(SO2F)2(简写为LiFSI)、LiClO4、LiAsF6、LiB(C2O4)2(简写为LiBOB)、LiBF2(C2O4)(简写为LiDFOB)、LiN(SO2RF)2或LiN(SO2F)(简写为SO2RF)等中的至少一种。添加剂例如选自碳酸亚乙烯酯(Vinylene Carbonate，VC)、氟代碳酸乙烯酯(Fluoroethylene Carbonate，FEC)、碳酸乙烯亚乙酯(4-Vinyl-1,3-dioxolan-2-one，VEC)、硫酸乙烯酯(DTD)、硫酸亚乙烯酯、1,3-丙烷磺内酯(1,3-Propanesultone，PS)、丙烯基磺酸内酯或1,4-丁烷磺酸内酯(1,4-Butanesultone)等中的一种或多种。且电解液400中添加剂的用量例如为电解液的1wt％-4wt％，又例如为2wt％。在本实施例中，有机溶剂例如为碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)的混合液，其中，EC、EMC和DEC的体积比例如为20:20:60，在含水量小于10ppm的氩气气氛手套箱中，将充分干燥的LiPF6溶解于上述混合的有机溶剂中，混合均匀后获得电解液，其中，LiPF6的浓度为1mol/L。3 , in one embodiment of the present invention, the electrolyte 400 includes, for example, an organic solvent, a lithium salt, and an additive, etc. The organic solvent is, for example, selected from one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). The lithium salt is , for example, at least one selected from LiPF6 , LiBF4 , LiN( SO2F ) 2 (abbreviated as LiFSI), LiClO4 , LiAsF6 , LiB( C2O4 ) 2 (abbreviated as LiBOB), LiBF2 ( C2O4 ) (abbreviated as LiDFOB), LiN ( SO2RF ) 2 or LiN ( SO2F ) (abbreviated as SO2RF ). The additive is selected from one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), 4-vinyl-1,3-dioxolan-2-one (VEC), dithiothreitol (DTD), vinyl sulfate, 1,3-propane sultone (PS), propene sultone or 1,4-butane sultone, etc. The amount of the additive in the electrolyte 400 is, for example, 1wt%-4wt% of the electrolyte, and another example is 2wt%. In this embodiment, the organic solvent is, for example, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), wherein the volume ratio of EC, EMC and DEC is, for example, 20:20:60. In an argon atmosphere glove box with a water content of less than 10 ppm, fully dried LiPF 6 is dissolved in the above-mentioned mixed organic solvent, and the electrolyte is obtained after uniform mixing, wherein the concentration of LiPF 6 is 1 mol/L.
为进一步理解本发明，引用具体的实施方式将更具体地解释本发明，这些实施例不应被理解为是限制性的。在与本发明主旨相一致的范围内，可以进行适当修改，其均落入本发明的技术范围内。For further understanding of the present invention, the present invention will be explained more specifically by citing specific embodiments, which should not be construed as limiting. In the scope consistent with the gist of the present invention, appropriate modifications can be made, which all fall within the technical scope of the present invention.
实施例1Example 1
正极极片的制备：将正极活性材料LiNi0.8Co0.1Mn0.1O2、粘接剂聚偏二氟乙烯以及导电剂乙炔黑按照质量比98:1:1混合，并加入溶剂N-甲基吡咯烷酮，在真空搅拌机中搅拌至均一透明状，获得正极浆料。将正极浆料均匀涂覆于16μm的铝箔集流体上，再将集流体在室温晾干后转移至烘箱，以100℃烘干6h，然后经过冷压、分切得到正极极片。Preparation of positive electrode sheet: positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 , binder polyvinylidene fluoride and conductive agent acetylene black were mixed in a mass ratio of 98:1:1, and solvent N-methylpyrrolidone was added, and stirred in a vacuum mixer until it was uniform and transparent to obtain positive electrode slurry. The positive electrode slurry was evenly coated on a 16μm aluminum foil current collector, and then the current collector was dried at room temperature and transferred to an oven, dried at 100°C for 6h, and then cold pressed and cut to obtain positive electrode sheets.
负极极片的制备：集流体选择铜箔，且将集流体依次通过无水乙醇、丙酮及去离子水在超声清洗仪里进行清洗，在真空干燥箱中以70℃干燥30min。将1.3wt％的第一粘结剂、97.3wt％的第一石墨和0.4wt％的导电剂进行干混，混合混匀后，加水搅拌30min，再加入0.5wt％第二粘结剂，继续高速分散90min，在加水调节浆料的固含量为55wt％时，加入0.5wt％第三粘结剂慢速搅拌30min，消泡处理，获得第一浆料。将1.3wt％的第一粘结剂、97.3wt％的第二石墨和0.4wt％的导电剂进行干混，混合混匀后，加水搅拌30min，再加入0.5wt％第二粘结剂，继续高速分散90min，在加水调节浆料的固含量为55wt％时，加入0.5wt％第三粘结剂慢速搅拌30min，消泡处理，获得第二浆料。其中，第一粘结剂为PAA粘结剂，导电剂为导电炭黑，第二粘结剂为CMC粘结剂，第三粘结剂为SBR粘结剂。在集流体的两侧上通过涂布磨头单层涂布第一浆料形成第一浆料层，对第一浆料层进行干燥处理。其中，第一浆料出料的D50为10.4μm。在第一浆料层干燥后，在集流体的两侧的第一浆料层上通过涂布磨头单层涂布第二浆料形成第二浆料层。其中，第二浆料出料的D50为24.8μm。将第一浆料层和第二浆料层进行烘干，形成第一负极活性物质层和第二负极活性物质层，第一负极活性物质层和第二负极活性物质层的总厚度为180μm，第一负极活性物质层的总厚度和第二负极活性物质层的总厚度之比ε为0.64。然后对集流体进行辊压和剪切等，以形成负极极片。Preparation of negative electrode sheet: Copper foil is selected as the current collector, and the current collector is cleaned in an ultrasonic cleaner with anhydrous ethanol, acetone and deionized water in turn, and dried in a vacuum drying oven at 70°C for 30 minutes. 1.3wt% of the first binder, 97.3wt% of the first graphite and 0.4wt% of the conductive agent are dry mixed, mixed and stirred for 30 minutes, and then 0.5wt% of the second binder is added, and high-speed dispersion is continued for 90 minutes. When the solid content of the slurry is adjusted to 55wt% by adding water, 0.5wt% of the third binder is added and stirred slowly for 30 minutes, and defoaming treatment is performed to obtain the first slurry. 1.3wt% of the first binder, 97.3wt% of the second graphite and 0.4wt% of the conductive agent were dry mixed, mixed and stirred for 30 minutes, and then 0.5wt% of the second binder was added, and the high-speed dispersion was continued for 90 minutes. When the solid content of the slurry was adjusted to 55wt% by adding water, 0.5wt% of the third binder was added and stirred slowly for 30 minutes, and the second slurry was obtained by defoaming. Among them, the first binder is PAA binder, the conductive agent is conductive carbon black, the second binder is CMC binder, and the third binder is SBR binder. The first slurry layer is formed by coating a single layer of the first slurry on both sides of the current collector, and the first slurry layer is dried. Among them, the D50 of the first slurry discharge is 10.4μm. After the first slurry layer is dried, the second slurry layer is formed by coating a single layer of the second slurry on the first slurry layer on both sides of the current collector. Among them, the D50 of the second slurry discharge is 24.8μm. The first slurry layer and the second slurry layer are dried to form a first negative electrode active material layer and a second negative electrode active material layer, the total thickness of the first negative electrode active material layer and the second negative electrode active material layer is 180 μm, and the ratio ε of the total thickness of the first negative electrode active material layer to the total thickness of the second negative electrode active material layer is 0.64. Then, the current collector is rolled and sheared to form a negative electrode sheet.
电解液的制备：将碳酸亚乙酯、碳酸甲乙酯和碳酸二乙酯按体积比为20:20:60混合。在含水量小于10ppm的氩气气氛手套箱中，将充分干燥的LiPF6溶解于混合有机溶剂中，混合均匀后获得电解液，其中，LiPF6的浓度为1mol/L。Preparation of electrolyte: Ethylene carbonate, ethyl methyl carbonate and diethyl carbonate were mixed in a volume ratio of 20:20:60. In an argon atmosphere glove box with a water content of less than 10 ppm, fully dried LiPF 6 was dissolved in a mixed organic solvent and mixed evenly to obtain an electrolyte, wherein the concentration of LiPF 6 was 1 mol/L.
隔膜的选择：选用12μm厚的聚丙烯隔膜。Selection of diaphragm: Use 12μm thick polypropylene diaphragm.
电池的制备：将制得的正极极片、隔膜、负极极片依次进行叠片，使隔膜处于正极极片和负极极片中间起到隔离的作用。然后外包铝塑膜，转移至真空烘箱中，120℃干燥，注入电解液3.0g/Ah后进行封口，经静置、热冷压、化成、夹具和分容等工序后，制备得容量为1Ah的软包电池。其中，化成步骤是将电解液进行注液后，在压力例如为0.1MPa且温度例如为45℃的热压环境，在静置状态下，以0.02C将电池充电17min。然后静置5min后，再以0.02C充到0.3Ah，之后割去气袋并真空封装，常温静置48h，从而使电解液完成化成。Preparation of the battery: The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role. Then wrap the aluminum plastic film, transfer to a vacuum oven, dry at 120°C, inject 3.0g/Ah of electrolyte and seal it. After standing, hot and cold pressing, formation, clamping and capacity division, a soft pack battery with a capacity of 1Ah is prepared. Among them, the formation step is to inject the electrolyte, and then charge the battery at 0.02C for 17min in a hot pressing environment with a pressure of, for example, 0.1MPa and a temperature of, for example, 45°C, in a static state. Then, after standing for 5min, charge it to 0.3Ah at 0.02C, then cut off the air bag and vacuum package it, and stand it at room temperature for 48h, so that the electrolyte is formed.
实施例2Example 2
第一负极活性物质层的总厚度为90μm，第二负极活性物质层的总厚度为90μm，即第一负极活性物质层的总厚度和第二负极活性物质层的总厚度之比ε为1，其它操作内容与实施例1相同。The total thickness of the first negative electrode active material layer is 90 μm, and the total thickness of the second negative electrode active material layer is 90 μm, that is, the ratio ε of the total thickness of the first negative electrode active material layer to the total thickness of the second negative electrode active material layer is 1, and other operations are the same as those in Example 1.
实施例3Example 3
第一负极活性物质层的总厚度为104μm，第二负极活性物质层的总厚度为76μm，即第一负极活性物质层的总厚度和第二负极活性物质层的总厚度之比ε为1.36，其它操作内容与实施例1相同。The total thickness of the first negative electrode active material layer is 104 μm, and the total thickness of the second negative electrode active material layer is 76 μm, that is, the ratio ε of the total thickness of the first negative electrode active material layer to the total thickness of the second negative electrode active material layer is 1.36. Other operations are the same as those in Example 1.
对比例1Comparative Example 1
在集流体上只设置第一负极活性物质层，且第一负极活性物质层的总厚度为180μm，其它操作内容与实施例1相同。Only the first negative electrode active material layer is disposed on the current collector, and the total thickness of the first negative electrode active material layer is 180 μm. Other operations are the same as those in Example 1.
对比例2Comparative Example 2
在集流体上只设置第二负极活性物质层，且第二负极活性物质层的总厚度为180μm，其它操作内容与实施例1相同。Only the second negative electrode active material layer is disposed on the current collector, and the total thickness of the second negative electrode active material layer is 180 μm. Other operations are the same as those in Example 1.
为验证实施例1-3和对比例1-2获得的负极极片的性能，在例如25℃的条件下，测试不同负极极片组成的电池的初始直流电阻(Directive Current Resistance，DCR)、初始容量和1C电流密度下循环500圈的容量保持率。To verify the performance of the negative electrode sheets obtained in Examples 1-3 and Comparative Examples 1-2, the initial direct current resistance (DCR), initial capacity and capacity retention rate after 500 cycles at a current density of 1C of batteries with different negative electrode sheet compositions were tested under conditions such as 25°C.
对实施例1-3和对比例1-2中负极极片制备的锂电池的性能进行测试，测试结果如表2所示。The performance of the lithium batteries prepared using the negative electrode sheets in Examples 1-3 and Comparative Examples 1-2 was tested, and the test results are shown in Table 2.
表2、实施例1-3和对比例1-2中制备的锂电池的性能Table 2. Performance of lithium batteries prepared in Examples 1-3 and Comparative Examples 1-2
请参阅表2所示，结合实施例1-3和对比例1，在集流体上只设置第一负极活性物质层时，锂电池的循环性能较好，但锂电池的初始DCR的数值较高，无法保证锂电池的快充性能。结合实施例1-3和对比例2，在集流体上只设置第二负极活性物质层时，锂电池的初始DCR的数值较低，锂电池的快充性能较好，但锂电池的容量和循环性能较差。结合实施例1-3和对比例1-2，在集流体上同时设置第一负极活性物质层和第二负极活性物质层时，锂电池的初始DCR的数值、容量以及循环性能能够同时兼顾，即能够保证锂电池的容量和循环性能，同时能够保证锂电池的快充/快放和高低温性能，获得具有良好的容量和循环稳定性的锂电池。Please refer to Table 2. In combination with Examples 1-3 and Comparative Example 1, when only the first negative electrode active material layer is set on the current collector, the cycle performance of the lithium battery is better, but the initial DCR value of the lithium battery is high, and the fast charging performance of the lithium battery cannot be guaranteed. In combination with Examples 1-3 and Comparative Example 2, when only the second negative electrode active material layer is set on the current collector, the initial DCR value of the lithium battery is low, and the fast charging performance of the lithium battery is good, but the capacity and cycle performance of the lithium battery are poor. In combination with Examples 1-3 and Comparative Example 1-2, when the first negative electrode active material layer and the second negative electrode active material layer are simultaneously set on the current collector, the initial DCR value, capacity and cycle performance of the lithium battery can be taken into account at the same time, that is, the capacity and cycle performance of the lithium battery can be guaranteed, and the fast charging/fast discharging and high and low temperature performance of the lithium battery can be guaranteed at the same time, so as to obtain a lithium battery with good capacity and cycle stability.
综上所述，本发明提出的锂电池负极极片及其制备方法与应用，通过在集流体上设置包括不同负极活性材料的负极活性物质层，靠近集流体的第一负极活性材料能够保证锂电池的容量和循环性能，远离集流体的第二负极活性材料能够保证锂电池的快充/快放和高低温性能，从而确保锂电池具备良好的低温性能和循环稳定性。通过粘结剂的混用，提高负极活性物质的含量，保证了负极极片的容量性能。第一浆料和第二浆料通过采用相同配方制备负极极片，能够提高负极极片的均匀性和一致性，能够提高锂电池的性能。通过双层涂布，提高负极活性物质层的厚度，以提高锂电池的容量。通过在集流体上设置多层负极活性物质层，且多层负极活性物质层选择不同性能的负极活性材料，以同时满足高动力学和长循环性能。In summary, the negative electrode sheet of a lithium battery proposed in the present invention and its preparation method and application, by arranging a negative electrode active material layer including different negative electrode active materials on the current collector, the first negative electrode active material close to the current collector can ensure the capacity and cycle performance of the lithium battery, and the second negative electrode active material far away from the current collector can ensure the fast charge/fast discharge and high and low temperature performance of the lithium battery, thereby ensuring that the lithium battery has good low temperature performance and cycle stability. By mixing the binder, the content of the negative electrode active material is increased, and the capacity performance of the negative electrode sheet is guaranteed. The first slurry and the second slurry are prepared by adopting the same formula to prepare the negative electrode sheet, which can improve the uniformity and consistency of the negative electrode sheet and improve the performance of the lithium battery. By double-layer coating, the thickness of the negative electrode active material layer is increased to increase the capacity of the lithium battery. By arranging multiple layers of negative electrode active material layers on the current collector, and selecting negative electrode active materials with different performances for the multiple layers of negative electrode active material layers, high dynamics and long cycle performance can be simultaneously met.
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明，本领域技术人员应当理解，本申请中所涉及的发明范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖在不脱离所述发明构思的情况下，由上述技术特征或其等同特征进行任意组合而形成的其它技术方案，例如上述特征与本申请中公开的(但不限于)具有类似功能的技术特征进行互相替换而形成的技术方案。除说明书所述的技术特征外，其余技术特征为本领域技术人员的已知技术，为突出本发明的创新特点，其余技术特征在此不再赘述。The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as the technical solution formed by replacing the above-mentioned features with the technical features with similar functions disclosed in this application (but not limited to). In addition to the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described in detail here.
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