CN112186273B - Winding core capable of reducing internal temperature rise for winding type lithium ion battery - Google Patents
Winding core capable of reducing internal temperature rise for winding type lithium ion battery Download PDFInfo
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- CN112186273B CN112186273B CN202011187030.XA CN202011187030A CN112186273B CN 112186273 B CN112186273 B CN 112186273B CN 202011187030 A CN202011187030 A CN 202011187030A CN 112186273 B CN112186273 B CN 112186273B
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- 238000004804 winding Methods 0.000 title claims abstract description 109
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 51
- 239000011248 coating agent Substances 0.000 claims abstract description 92
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 5
- 238000005096 rolling process Methods 0.000 description 5
- 238000010280 constant potential charging Methods 0.000 description 4
- 238000010277 constant-current charging Methods 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
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- 238000004519 manufacturing process Methods 0.000 description 2
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- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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- 239000007924 injection Substances 0.000 description 1
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- 239000004816 latex Substances 0.000 description 1
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000009517 secondary packaging Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- H01M10/058—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
-
- 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
- H01M10/60—Heating or cooling; Temperature control
- H01M10/61—Types of temperature control
- H01M10/613—Cooling or keeping cold
-
- 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
- H01M4/624—Electric conductive fillers
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a winding core for a winding type lithium ion battery, which can reduce the internal temperature rise, wherein a positive plate is used in the winding core, the impedance value of the initial area of the positive plate is reduced by coating different positive active material layers on the initial area and other areas along the length direction of a positive current collector in the positive plate, and the heat generation quantity of a high-temperature hot area which is difficult to radiate in the battery is reduced under the condition of high-rate charging, so that the temperature rise of the battery under the condition of high-rate charging is reduced. In addition, when the impedance is reduced by increasing the content of the conductive agent in the initial region of the positive plate and the like, other regions can still be coated with higher content of active substances, and the technical effect of reducing the temperature rise of the battery and reducing the energy density loss is achieved.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a winding core for a winding type lithium ion battery and the winding type lithium ion battery with the winding core, wherein the winding core can reduce internal temperature rise.
Background
With the arrival of the 5G era, the demand of users for cruising ability of electronic products such as mobile phones and notebook computers is continuously increasing. Therefore, while pursuing the energy density of the battery, it is urgent to configure a high-efficiency quick-charging capability for the lithium ion battery, and it is a key point in the development of the lithium ion battery to continuously improve the charging rate of the battery. However, the heat generated by the battery is remarkably increased by rapid charging under a large multiplying power, a high-temperature hot area in a certain range is formed in the battery, and the heat in the battery is not easily transferred to the outside of the battery, so that the overall temperature rise of the battery is overhigh in the charging process. And too high temperature of the battery can affect the stability of the anode and cathode, electrolyte and the like in the battery, some side reactions are formed in the battery, the performance of the battery is deteriorated, and heat can be out of control under severe conditions.
In the prior art, different pole piece structures, such as a tab middle-arranged structure, a multi-tab structure and the like, are adopted, and compared with a conventional winding type battery, the improvement obviously reduces the overall impedance of the battery, can realize the effect of reducing the charging temperature rise of the battery to a certain extent, but has no obvious improvement effect on improving a high-temperature hot area which is difficult to dissipate heat in the battery.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a winding core for a winding type lithium ion battery, which can reduce the internal temperature rise, and can solve the problem that the high-temperature hot area which is difficult to radiate heat inside the winding core for the winding type lithium ion battery generates much heat and the overall temperature rise of the battery is overhigh under the condition of high-rate charging.
In the present invention, the term "winding core" refers to a winding type lithium ion battery cell.
The purpose of the invention is realized by the following technical scheme:
a winding core for a winding type lithium ion battery comprises a negative plate, a diaphragm and a positive plate, wherein the positive plate, the negative plate and the diaphragm form the winding core for the winding type lithium ion battery in a winding mode; the positive plate comprises a positive current collector, and a first coating area and a second coating area which are arranged on at least one surface (such as a first surface and a second surface) of the positive current collector along the length direction of the positive current collector, wherein the impedance of the first coating area is smaller than that of the second coating area; and the first coating area forms the inner ring of the winding core for the winding type lithium ion battery, and the second coating area forms the outer ring of the winding core for the winding type lithium ion battery.
In the present invention, the "winding method" is a winding core for a wound lithium ion battery, which is formed by stacking a separator, a positive electrode sheet, a separator, a negative electrode sheet, and a separator in this order, and then winding the stack in the winding direction in which the longitudinal direction of the positive electrode current collector is the winding core.
In the invention, the outer ring of the winding core for the winding type lithium ion battery and the inner ring of the winding core for the winding type lithium ion battery are opposite, the outer side close to the winding core is the outer ring, the inner side close to the winding core is the inner ring, the first coating area forms the inner ring of the winding core for the winding type lithium ion battery, and the second coating area forms the outer ring of the winding core for the winding type lithium ion battery.
According to the invention, the impedance R of said first coating zone1Is 50-500 Ω cm, and the impedance R of the second coating region2Is 100-1000 Ω cm, and the impedance of the first coated region is less than the impedance of the second coated region.
According to the invention, the impedance R of said first coating zone1And the impedance R of the second coated region2Satisfies the following conditions: r1/R2Less than or equal to 90 percent, such as 80 percent, 70 percent, 60 percent and 50 percent.
According to the invention, n/m is 1: 9-9: 1, n is the number of folds formed by the first coating area, and m is the number of folds formed by the second coating area. Illustratively, n/m is 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9: 1. In the invention, the fold number n formed by the first coating area refers to the fold number formed when the first coating area is wound along the length direction of the positive electrode current collector; the number of folds m formed in the second coating region means the number of folds formed when the second coating region is wound in the longitudinal direction of the positive electrode current collector. The number of folds formed by the first coating region and the number of folds formed by the second coating region can be adjusted according to different types of batteries, and illustratively, for 386283 types of batteries, n is an integer between 2 and 18, and m is an integer between 2 and 18.
According to the invention, d is 0.08 ≦ d1/d2Less than or equal to 0.75; wherein d is1Thickness of inner ring of winding core for wound lithium ion battery formed for first coating region, d2The thickness of the whole winding core. The thickness of the winding core can be adjusted according to batteries of different models, illustratively, d is more than or equal to 0.16mm and more than or equal to 386283 models for the battery of 386283 models1≤15mm，2mm≤d2≤20mm。
According to the invention, the first coating area takes the positive current collector as a symmetry axis, and the coating pastes are symmetrically arranged on the two side surfaces of the positive current collector, namely the coating lengths of the coating pastes on the two side surfaces of the positive current collector are the same. The second coating area takes the positive current collector as an axis, the coating paste is arranged on the surfaces of two sides of the positive current collector, and the coating length of the coating paste on one side is greater than that of the coating paste on the other side.
In the conventional coiling type lithium ion battery is with rolling up the core, work as coiling type lithium ion battery be used for the big multiplying power charging process with rolling up the core in, the heat of rolling up the core inner ring is more difficult for effluvium, and the heat yield that lasts increases and slow heat dissipation can lead to the inner ring to form the high temperature hot area gradually, makes the holistic temperature rise of battery great. In the invention, the positive plates coated with different impedances are used, and the impedance of the first coating area in the positive plate is smaller than that of the second coating area, so that the heat generation quantity of the inner ring high-temperature hot area in the prepared winding core is reduced, and the temperature rise of the whole battery is reduced.
In one embodiment, the first coating region includes a first positive electrode active material layer disposed on first and second surfaces of a positive electrode current collector, the first positive electrode active material layer including a first positive electrode active material, a first conductive agent, and a first binder.
In one embodiment, the second coating region includes a second positive electrode active material layer disposed on the first surface and the second surface of the positive electrode current collector, the second positive electrode active material layer including a second positive electrode active material, a second conductive agent, and a second binder.
Illustratively, the lengths of the second positive electrode active material layers disposed on the first and second surfaces of the positive electrode current collector are different, i.e., a one-side coated region is formed on the surface of the positive electrode current collector, the length of the one-side coated region is not particularly limited, and the specific structure is as shown in fig. 1.
In one embodiment, the content x of the first conductive agent1Greater than the content x of the second conductive agent2Excellence inSelecting 0 wt%<x2<x112% by weight or less, preferably 1% by weight or less and x2<x1Less than or equal to 12 weight percent. The content of the first conductive agent is the mass percentage content of the first conductive agent in the total mass of the first positive electrode active material layer, and the content of the second conductive agent is the mass percentage content of the second conductive agent in the total mass of the second positive electrode active material layer.
The high mass percentage of the first conductive agent may lower the resistance of the first coated region, thereby reducing heat generation, while the low mass percentage of the second conductive agent may ensure an increased amount of the second active material in the second coated region, thereby reducing the loss of energy density of the battery as a whole.
In one embodiment, the particle diameter D of the first positive electrode active material50aD is not less than 3 mu m50aLess than or equal to 15 mu m, and the particle diameter D of the second positive electrode active material50bD is less than or equal to 6 mu m50bLess than or equal to 30 mu m, and the particle diameter D of the first positive electrode active material50aIs smaller than the particle diameter D of the second positive electrode active material50b。
In one embodiment, the negative electrode sheet has a structure and composition suitable for a winding core for a wound lithium ion battery, which is commonly used in the art.
In one embodiment, the first positive electrode active material and the second positive electrode active material forming the first positive electrode active material layer and the second positive electrode active material layer are the same or different, the first conductive agent and the second conductive agent are the same or different, and the first binder and the second binder are the same or different.
In one embodiment, the first positive electrode active material layer comprises the following components in percentage by mass:
78-98.9 wt% of first positive electrode active material, 0.1-12 wt% of first conductive agent and 1-10 wt% of first binder.
In one embodiment, the second positive electrode active material layer comprises the following components in percentage by mass:
78-98.9 wt% of second positive electrode active material, 0.1-12 wt% of second conductive agent and 1-10 wt% of second binder.
Wherein the first conductive agent and the second conductive agent are the same or different and are independently selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder and carbon fiber.
Wherein the first binder and the second binder are the same or different and are independently selected from at least one of sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene, polyvinylidene fluoride and polyethylene oxide.
The first positive electrode active material and the second positive electrode active material are the same or different and are independently selected from lithium cobaltate, lithium iron phosphate and ternary positive electrode materials.
In one embodiment, the positive electrode sheet further comprises tabs, the positions where the tabs are arranged are not particularly limited, and the number of the tabs arranged is not particularly limited; for example, the winding core can adopt a conventional winding structure, namely, the tab is located in an empty foil area of the winding start position of the positive plate; the winding core can also adopt a tab middle-arranged or multi-tab structure, namely the tab is positioned in the coating area of the positive plate.
In one embodiment, the positive electrode active material layer in the first and second coating regions may be coated in a single layer, or may be coated in two or more layers.
The invention also provides a preparation method of the winding core for the winding type lithium ion battery, which comprises the following steps:
(1) preparing a positive plate, a negative plate and a diaphragm, wherein the positive plate comprises a positive current collector, and a first coating area and a second coating area which are arranged on at least one surface (such as a first surface and a second surface) of the positive current collector along the length direction of the positive current collector, and the impedance of the first coating area is smaller than that of the second coating area;
(2) and forming a winding core by the anode plate, the cathode plate and the diaphragm in a winding mode, wherein the first coating area forms an inner ring of the winding core for the winding type lithium ion battery, and the second coating area forms an outer ring of the winding core for the winding type lithium ion battery.
The invention also provides a winding type lithium ion battery, and the winding core of the battery is the winding core for the winding type lithium ion battery.
The invention has the beneficial effects that:
the magnitude of charging temperature rise of a winding core for a conventional winding type lithium ion battery depends on the heat generation amount and the heat dissipation amount during charging, the heat dissipation amount is related to the heat conductivity of materials and the shape and the structure of a battery body, the heat dissipation speed in the battery is lower relative to the surface of the battery, and a high-temperature hot area is easily formed during charging under high multiplying power; the key factors influencing the heat production quantity are the impedance and the charging rate of the battery, and the lower the impedance or the charging rate is, the smaller the heat production quantity of the battery is, and the corresponding temperature rise is also smaller.
Based on the above, the invention provides a winding core for a winding type lithium ion battery, which can reduce the internal temperature rise, wherein a positive plate is used in the winding core, the impedance value of the initial region of the positive plate is reduced by coating different active material layers on the initial region and other regions of the positive plate along the length direction of a positive current collector, and the heat generation quantity of a high-temperature hot region which is difficult to radiate inside the battery is reduced under the condition of high-rate charging, so that the temperature rise of the battery under the condition of high-rate charging is reduced. In addition, when the impedance is reduced by increasing the content of the conductive agent in the initial region of the positive plate and the like, other regions can still be coated with higher content of active substances, and the technical effect of reducing the temperature rise of the battery and reducing the energy density loss is achieved.
Drawings
Fig. 1 is a schematic structural diagram of a positive plate of a winding core for a winding lithium ion battery according to the present invention.
Fig. 2 is a schematic structural diagram of a winding core for a winding lithium ion battery according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples. 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.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
In the description of the present invention, it should be noted that the terms "first", "second", etc. are used for descriptive purposes only and do not indicate or imply relative importance.
Example 1
The positive electrode active material lithium cobaltate (particle diameter D)5014 mu m), a binder PVDF and a conductive agent conductive carbon black are mixed according to the mass ratio of 90.5:4.5:5, and then N-methyl pyrrolidone is added to be stirred and dispersed to prepare positive electrode slurry 1 with proper solid content.
The positive electrode active material lithium cobaltate (particle diameter D)5014 mu m), a binder PVDF and a conductive agent conductive carbon black are mixed according to the mass ratio of 97.9:1:1.1, and then N-methyl pyrrolidone is added to be stirred and dispersed to prepare positive electrode slurry 2 with proper solid content.
Coating the positive electrode slurry 1 on the surfaces of two sides of a current collector at the head of the positive electrode current collector by using a coating machine to form a first coating area; coating the positive electrode slurry 2 on the surfaces of the two sides of the current collector at the other part of the positive electrode current collector to form a second coating area tightly connected with the first coating area, and performing the procedures of drying, rolling, slitting, sheet making and the like to obtain a positive electrode sheet, wherein the area ratio of the first coating area to the second coating area is 1: 1; the sheet resistance value of the positive plate in the first coating area is 50 omega cm and the sheet resistance value of the positive plate in the second coating area is 600 omega cm.
Adding 0.5 wt% of conductive carbon, 1.3 wt% of styrene butadiene rubber and 1.3 wt% of carboxymethyl cellulose into 96.9 wt% of negative active material graphite, then adjusting with water to prepare negative slurry, coating the negative slurry on a current collector, and carrying out the working procedures of drying, rolling, slitting, sheet making and the like to obtain a negative sheet.
And winding the obtained positive plate and negative plate together with the diaphragm into a winding core, wherein the first coating area forms the inner ring of the winding core for the winding type lithium ion battery, and the second coating area forms the outer ring of the winding core for the winding type lithium ion battery. And packaging the wound battery by using the aluminum plastic film after winding to form a winding core, and finally carrying out electrical property test on the battery through the processes of liquid injection, formation, secondary packaging, sorting, aging and the like.
Examples 2 to 7
Examples 2 to 7 were otherwise the same as example 1 except that the areas of the first coated region and the second coated region were different, i.e., the fold formed by the first coated region and the fold formed by the second coated region were different; the positive electrode slurry 1 and the positive electrode slurry 2 have different contents of the conductive agent, and the positive electrode active particles D of the positive electrode slurry 1 and the positive electrode slurry 2 are different50The differences are specifically shown in table 1.
Comparative example 1
The other portions are the same as example 1 except that both the first coated region and the second coated region of the positive electrode sheet are coated with the positive electrode slurry 2.
Comparative example 2
The other portions are the same as example 1 except that both the first coated region and the second coated region of the positive electrode sheet are coated with the positive electrode slurry 1.
Comparative example 3
The other portions are the same as example 1, except that the positions of the first coating region and the second coating region of the positive electrode sheet are switched, the first coating region is disposed on the outer side of the winding core, and the second coating region is disposed on the inner side.
The batteries prepared in the above examples and comparative examples were subjected to a temperature rise test and an energy density test, which were as follows:
(1) temperature rise Performance test
After being placed for 2 hours at the ambient temperature of 25 +/-2 ℃, the winding core is subjected to step charging: constant current charging to 4.25V at 3C rate, constant voltage charging to 2.5C at 4.25V voltage, constant current charging to 4.35V at 2.5C rate, constant voltage charging to 2C at 4.35V voltage, constant current charging to 4.4V at 2C rate, constant voltage charging to 1.5C at 4.4V voltage, constant current charging to 4.48V at 1.5C rate, constant voltage charging to 0.025C at 4.48V voltage, standing for 5min, then discharging at 0.7C, cutting off voltage 3.0V, standing for 4 h. The temperature change of the battery body in the charging process is monitored by circulating the steps for 3 times.
(2) Energy density
The energy density here is a volume energy density (wh/L) which is a table capacity (Ah) x a system plateau voltage (V)/a core volume (L) at room temperature.
The results of the temperature rise test and the results of the energy density test for each example and comparative example are shown in table 1.
TABLE 1 temperature rise test result and energy density test result of each example and comparative example
From the examples 1 to 3, it can be seen that increasing the fraction ratio of the first coating region in the positive plate can gradually decrease the temperature rise of the winding core body, and accordingly, the energy density loss is increased. As can be seen from example 1 and examples 4 to 6, as the content of the conductive agent in the first coated region in the positive electrode sheet increases, the temperature rise of the jelly roll body gradually decreases, and accordingly, the energy density loss increases. As can be seen from examples 1 and 7, D of the positive electrode active material according to the first coating region in the positive electrode sheet50The temperature rise of the roll core body is reduced, and correspondingly, the energy density is slightly reduced.
It can be seen from example 1 and comparative example 1 that, in example 1, the content of the conductive agent in the first coating region in the positive plate is increased, so that the temperature rise of the winding core body is remarkably reduced, and the energy density is lost to a certain extent. As can be seen from example 1 and comparative examples 1 to 2, when the content of the conductive agent in the positive electrode sheet as a whole is reduced, compared with the case where the content of the conductive agent in the middle-first coated region is merely increased, the temperature rise of the battery body is significantly reduced, but at the same time, the reduction in energy density is also large. As can be seen from example 1 and comparative example 3, the positions of the first coating region and the second coating region of the positive electrode sheet were switched, the first coating region was disposed on the outer side of the winding core, and the second coating region was disposed on the inner side. The energy density was unchanged, but the temperature rise increased significantly.
In conclusion, the positive plate with the first coating area and the second coating area with different impedances can reduce the temperature rise of the battery body and ensure the energy density.
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 (11)
1. A winding core for a winding type lithium ion battery,
the winding core comprises a negative plate, a diaphragm and a positive plate, and the positive plate, the negative plate and the diaphragm form the winding core for the winding type lithium ion battery in a winding mode; the positive plate comprises a positive current collector, and a first coating area and a second coating area which are arranged on at least one surface of the positive current collector along the length direction of the positive current collector, wherein the impedance of the first coating area is smaller than that of the second coating area; and the first coating area forms the inner ring of the winding core for the winding type lithium ion battery, and the second coating area forms the outer ring of the winding core for the winding type lithium ion battery.
2. The winding core for a wound lithium ion battery according to claim 1,
resistance R of the first coating region1Is 50-500 Ω cm, and the impedance R of the second coating region2Is 100-1000 Ω cm, and the impedance of the first coated region is less than the impedance of the second coated region.
3. The winding core for a wound lithium ion battery according to claim 1 or 2,
resistance R of the first coating region1And the impedance R of the second coated region2Satisfies the following conditions: r1/R2≤90％。
4. The winding core for a wound lithium ion battery according to claim 1,
n/m is 1:9 to 9:1, n is the number of folds formed by the first coating region, and m is the number of folds formed by the second coating region.
5. The winding core for a wound lithium ion battery according to claim 1,
0.08≤d1/d2≤0.75；d1thickness of inner ring of winding core for wound lithium ion battery formed for first coating region, d2The thickness of the whole winding core.
6. The winding core for a wound lithium ion battery according to claim 1,
the first coating area takes the positive current collector as a symmetry axis, and the coating pastes are symmetrically arranged on the two side surfaces of the positive current collector, namely the coating lengths of the coating pastes on the two side surfaces of the positive current collector are the same; and/or the presence of a gas in the gas,
the second coating area takes the positive current collector as an axis, the coating paste is arranged on the surfaces of two sides of the positive current collector, and the coating length of the coating paste on one side is greater than that of the coating paste on the other side.
7. The winding core for a wound lithium ion battery according to claim 1,
the first coating region includes a first positive electrode active material layer disposed on first and second surfaces of a positive electrode current collector, the first positive electrode active material layer including a first positive electrode active material, a first conductive agent, and a first binder; and/or the presence of a gas in the gas,
the second coating region includes a second positive electrode active material layer disposed on the first surface and the second surface of the positive electrode current collector, the second positive electrode active material layer including a second positive electrode active material, a second conductive agent, and a second binder.
8. The winding core for a wound lithium ion battery according to claim 7,
the content x of the first conductive agent1Greater than the content x of the second conductive agent2。
9. The winding core for a wound lithium ion battery according to claim 8,
0wt％<x2<x1≤12wt％。
10. the winding core for a wound lithium ion battery according to claim 7,
the particle diameter D of the first positive electrode active material50aD is not less than 3 mu m50aLess than or equal to 15 mu m, and the particle diameter D of the second positive electrode active material50bD is less than or equal to 6 mu m50bLess than or equal to 30 mu m, and the particle diameter D of the first positive electrode active material50aIs smaller than the particle diameter D of the second positive electrode active material50b。
11. A wound lithium ion battery, wherein the winding core of the battery is the winding core for a wound lithium ion battery according to any one of claims 1 to 10.
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| CN113270661A (en) * | 2021-05-13 | 2021-08-17 | 珠海冠宇电池股份有限公司 | Pole piece and battery |
| CN113314697A (en) * | 2021-05-27 | 2021-08-27 | 珠海冠宇电池股份有限公司 | Battery core and battery |
| CN114242935A (en) * | 2021-12-16 | 2022-03-25 | 珠海冠宇电池股份有限公司 | Electrode assembly and application thereof |
| CN114420941A (en) * | 2022-03-30 | 2022-04-29 | 宁德新能源科技有限公司 | Current collector, pole piece, electrochemical device and electronic device |
| CN116936720A (en) * | 2022-03-31 | 2023-10-24 | 宁德时代新能源科技股份有限公司 | Electrode assembly, battery cell, battery, electric equipment, winding equipment and method |
| CN115763692B (en) * | 2022-09-08 | 2024-05-10 | 江苏正力新能电池技术有限公司 | Positive plate and battery |
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| JP6349211B2 (en) * | 2014-09-17 | 2018-06-27 | 古河機械金属株式会社 | Positive electrode material, positive electrode, and lithium ion battery |
| JP2016081605A (en) * | 2014-10-10 | 2016-05-16 | トヨタ自動車株式会社 | Lithium ion secondary battery |
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| CN106684458B (en) * | 2017-01-22 | 2019-09-17 | 湖南立方新能源科技有限责任公司 | A kind of lithium ion battery and preparation method thereof improving low temperature charge-discharge performance |
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| CN209822791U (en) * | 2019-06-03 | 2019-12-20 | Oppo广东移动通信有限公司 | Winding battery core, battery and electronic equipment |
| CN111785925B (en) * | 2020-08-11 | 2023-06-02 | 天津市捷威动力工业有限公司 | Pole piece and application thereof, and low-temperature-rise high-safety lithium ion battery containing same |
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