CN113314697A - Battery core and battery - Google Patents
Battery core and battery Download PDFInfo
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- CN113314697A CN113314697A CN202110585395.6A CN202110585395A CN113314697A CN 113314697 A CN113314697 A CN 113314697A CN 202110585395 A CN202110585395 A CN 202110585395A CN 113314697 A CN113314697 A CN 113314697A
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- 239000002184 metal Substances 0.000 claims abstract description 30
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000011777 magnesium Substances 0.000 claims abstract description 25
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 23
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 16
- 239000004411 aluminium Substances 0.000 claims abstract description 4
- 239000011247 coating layer Substances 0.000 claims description 28
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 238000007600 charging Methods 0.000 abstract description 14
- 238000007599 discharging Methods 0.000 abstract description 14
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- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 239000006258 conductive agent Substances 0.000 description 4
- 238000010280 constant potential charging Methods 0.000 description 4
- 238000010277 constant-current charging Methods 0.000 description 4
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
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- 239000011572 manganese Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat 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
- H01M10/058—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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
The invention provides a battery cell and a battery, wherein the battery cell comprises: positive plate, negative pole piece and diaphragm, the diaphragm is located positive plate with between the negative pole piece, positive plate includes first pole piece portion and second pole piece portion, first pole piece portion is located the intermediate position of electric core, second pole piece portion is located the outside of first pole piece portion, the metallic element's of the coating that first pole piece portion includes content is greater than the metallic element's of the coating that second pole piece portion includes content, metallic element includes aluminium element and magnesium element. In this way, the content of the metal element of the coating included in the first pole piece part is greater than that of the metal element of the coating included in the second pole piece part, that is, the content of the metal element of the coating included in the first pole piece part is higher, so that the stability of the positive pole piece during charging and discharging can be better, and the cycle performance of the whole battery cell can be improved.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a battery core and a battery.
Background
With the development of battery technology, batteries have been widely used in human life. Meanwhile, the kinds of batteries are increasing. In the process of implementing the invention, the inventor finds that the following problems exist in the prior art: the current battery is generally a rechargeable battery, but in the process of charging and discharging, a high-temperature hot area is easily formed inside a battery core of the battery, so that the battery core is easily subjected to an excessive lithium removal phenomenon, and the charging and discharging stability of the battery core is poor.
Disclosure of Invention
The embodiment of the invention aims to provide a battery cell and a battery, and solves the problem of poor charging and discharging stability of the battery cell.
In order to achieve the above object, an embodiment of the present invention provides a battery cell, including: positive plate, negative pole piece and diaphragm, the diaphragm is located positive plate with between the negative pole piece, positive plate includes first pole piece portion and second pole piece portion, first pole piece portion is located the intermediate position of electric core, second pole piece portion is located the outside of first pole piece portion, the metallic element's of the coating that first pole piece portion includes content is greater than the metallic element's of the coating that second pole piece portion includes content, metallic element includes aluminium element and magnesium element.
Optionally, the anode plate comprises a coating layer with the content of aluminum element of 4000-9000 ppm.
Optionally, the content of the magnesium element in the coating layer included in the positive electrode plate is 500-3000 ppm.
Optionally, the battery cell is a winding battery cell, the first pole piece portion constitutes a central region of the winding battery cell, and the second pole piece portion constitutes an outer region adjacent to the central region.
Optionally, a ratio of the number of folds of the first pole piece portion and the second pole piece portion ranges from 1/9 to 9/1.
Optionally, the battery cell is a laminated battery cell, the laminated battery cell includes a plurality of positive plates, and the plurality of positive plates include a first positive plate and a second positive plate, the first positive plate is a positive plate located at a plurality of middle positions of the positive plates, the second positive plate is a positive plate located at a plurality of outer positions of the positive plates, and a content of a metal element of a coating included in the first positive plate is greater than a content of a metal element of a coating included in the second positive plate.
Optionally, the laminated cell comprises positive plates including a coating layer having a gradually decreasing content of metal elements in a direction from the first positive plate to the second positive plate.
Optionally, the content of the aluminum element in the coating included in the first pole piece portion is 6000-9000ppm, and the content of the aluminum element in the coating included in the second pole piece portion is 5000-8000 ppm.
Optionally, the content of the magnesium element in the coating included in the first pole piece portion is 1000-3000ppm, and the content of the magnesium element in the coating included in the second pole piece portion is 500-2000 ppm.
The embodiment of the invention also provides a battery, which comprises the battery core.
One of the above technical solutions has the following advantages or beneficial effects:
in an embodiment of the present invention, a battery cell includes: positive plate, negative pole piece and diaphragm, the diaphragm is located positive plate with between the negative pole piece, positive plate includes first pole piece portion and second pole piece portion, first pole piece portion is located the intermediate position of electric core, second pole piece portion is located the outside of first pole piece portion, the metallic element's of the coating that first pole piece portion includes content is greater than the metallic element's of the coating that second pole piece portion includes content, metallic element includes aluminium element and magnesium element. In this way, the content of the metal element of the coating included in the first pole piece part is greater than that of the metal element of the coating included in the second pole piece part, that is, the content of the metal element of the coating included in the first pole piece part is higher, so that the stability of the positive pole piece during charging and discharging can be better, and the cycle performance of the whole battery cell can be improved.
Drawings
Fig. 1 is a schematic structural diagram of a positive plate of a battery cell according to an embodiment of the present invention;
fig. 2 is one of schematic structural diagrams of a battery cell according to an embodiment of the present invention;
fig. 3 is a second schematic structural diagram of a battery cell according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 3, fig. 2 and fig. 3 are schematic structural diagrams of a battery cell according to an embodiment of the present invention, respectively, as shown in fig. 1, the battery cell includes: the positive plate 10 comprises a first plate part 11 and a second plate part 12, the first plate part 11 is located in the middle of the battery core, the second plate part 12 is located on the outer side of the first plate part 11, the first plate part 11 comprises a coating with a metal element content larger than that of the second plate part 12, and the metal element comprises aluminum and magnesium.
The content of the metal element in the present invention is a mass content, and ppm means part per million (parts per million). In the battery product, the content of the metal element can be obtained by the ICP detection after the coating on the positive plate is scraped.
In which, the positive plate 10 includes a current collector (which may be an aluminum foil) and a coating layer on the surface of the current collector, and at the same time, the positive plate 10 includes a first plate portion 11 and a second plate portion 12, so it can be understood that the first plate portion 11 includes a first current collector portion and a first coating portion, the second plate portion 12 includes a second current collector portion and a second coating portion, and the first current collector portion and the second current collector portion constitute the current collector, and the first coating portion and the second coating portion constitute the coating layer, that is: the first pole piece portion 11 in the embodiment of the present invention may include a coating layer understood as a first coating portion, and the second pole piece portion 12 may include a coating layer understood as a second coating portion.
The working principle of the embodiment of the invention can be expressed as follows:
in the embodiment of the present invention, the first pole piece portion 11 is located at the middle position of the battery cell, and the content of the metal element in the coating layer included in the first pole piece portion 11 is greater than the content of the metal element in the coating layer included in the second pole piece portion 12, that is, the content of the metal element in the coating layer included in the first pole piece portion 11 is higher, so that the stability of the positive pole piece 10 during charging and discharging (particularly, high-temperature and high-voltage charging and discharging) is better, and the cycle performance of the entire battery cell is improved. Meanwhile, because the content of the metal element of the coating included in the first pole piece portion 11 is greater than the content of the metal element of the coating included in the second pole piece portion 12, which is equivalent to only increasing the content of the metal element of the coating included in the first pole piece portion 11, the phenomena of 10 g capacity loss of the positive pole piece and the like are reduced, and the energy density loss of the battery cell is reduced, that is, the embodiment of the invention can simultaneously give consideration to the good cycle performance and the good energy density of the battery cell.
Wherein, the first pole piece portion 11 and the second pole piece portion 12 may be adjacently disposed, that is, the first pole piece portion 11 and the second pole piece portion 12 may be connected to each other, for example: the first pole piece portion 11 and the second pole piece portion 12 may be located on the same horizontal plane (the horizontal plane may be regarded as a plane where the positive pole piece 10 is located), and the areas where the first pole piece portion 11 and the second pole piece portion 12 are located may be two different areas of the horizontal plane, respectively. It should be noted that, when the first pole piece portion 11 is located at the middle position of the battery cell, it may be understood that the positive pole piece 10 is located at the middle position of the battery cell, and the first pole piece portion 11 and the second pole piece portion 12 may be both located at the middle position of the battery cell, for example: the first pole piece portion 11 may be located at a position to the left of the middle of the cell, and the second pole piece portion 12 may be located at a position to the right of the middle of the cell.
The first pole piece 11 and the second pole piece 12 may be provided at an interval, for example: the first pole piece portion 11 and the second pole piece portion 12 may be connected by an intermediate pole piece portion. Thus, the first and second pole piece portions 11 and 12 may be located at opposite ends of the positive pole piece 10, respectively.
As an alternative embodiment, the metal element in the positive electrode material of the positive electrode sheet 10 may be obtained by doping or cladding.
It should be noted that the specific content of the aluminum element and the magnesium element in the coating layer included in the positive electrode sheet 10 is not limited herein, for example: as an alternative embodiment, the positive electrode sheet 10 includes a coating layer containing 4000-9000ppm of aluminum element. As another alternative embodiment, the positive electrode sheet 10 includes a coating layer containing magnesium in an amount of 500-3000 ppm. Therefore, by the mode, the stability of the battery cell in the charging process can be enhanced, and meanwhile, the diversity and the flexibility of the setting mode of the content of the aluminum element and the content of the magnesium element can be enhanced.
The ppm may refer to parts per million, and the content of the metal element may also be represented by a percentage, which is not described herein in detail.
In addition, as another optional embodiment, the positive electrode sheet 10 includes a coating layer containing 5500-7500ppm of aluminum element; as another alternative embodiment, the positive electrode sheet 10 includes a coating layer containing magnesium in an amount of 1000-2000 ppm. Thus, the diversity and flexibility of the setting mode of the content of the aluminum element and the magnesium element can be further enhanced.
Of course, the contents of the aluminum element and the magnesium element of the coating layer included in the first pole piece portion 11 and the coating layer included in the second pole piece portion 12 may also be different, for example: as an alternative embodiment, the first pole piece portion 11 includes a coating layer with an aluminum content of 6000-9000 ppm; as an alternative embodiment, the second pole piece portion 12 includes a coating having an aluminum content of 5000-.
As another alternative embodiment, the first pole piece portion 11 includes a coating layer with an aluminum content of 6500-; as another alternative, the second pole piece portion 12 includes a coating having an elemental aluminum content of 5500-7500 ppm.
As another alternative embodiment, the first pole piece portion 11 includes a coating layer with a magnesium element content of 1000-3000 ppm; as another alternative, the second pole piece portion 12 includes a coating having a magnesium content of 500-2000 ppm.
As another alternative embodiment, the first pole piece portion 11 includes a coating layer with a magnesium element content of 1500-; as another alternative, the second pole piece portion 12 includes a coating having a magnesium content of 700-1500 ppm.
Thus, the diversity and flexibility of the setting modes of the contents of the aluminum element and the magnesium element can be further enhanced through the mode.
It should be noted that, the specific structure of the battery cell is not limited herein, for example: the battery cell can be a winding battery cell or a laminated battery cell. The winding type cell may refer to a single positive electrode sheet 10, a single negative electrode sheet 20, and a single separator 30, which are bent multiple times to form a multilayer structure (each layer structure may include a portion of the positive electrode sheet 10, a portion of the negative electrode sheet 20, and a portion of the separator 30, and the portion of the positive electrode sheet 10, the portion of the negative electrode sheet 20, and the portion of the separator 30 may be referred to as a one-layer cell structure). While the laminated cell can be considered to be formed by stacking a plurality of positive electrode sheets 10, a plurality of negative electrode sheets 20 and a plurality of separators 30, each positive electrode sheet 10, the corresponding negative electrode sheet 20 and the corresponding separator 30 can be referred to as a set of laminated sheets.
As an alternative embodiment, referring to fig. 2, the cell is a winding cell, the first pole piece 11 forms a central region of the winding cell, and the second pole piece 12 forms an outer region adjacent to the central region. In this way, since the first pole piece portion 11 is located in the central region of the battery cell, the content of the metal element in the coating layer included in the central region is high, so that the stability of the positive pole piece 10 during charging and discharging (particularly, high-temperature and high-voltage charging and discharging) is high, and the cycle performance of the whole battery cell is improved.
Note that the center region differs from the intermediate position of the above embodiment: the middle position may refer to all positions on a horizontal plane located in the middle of the cell, and the central region may refer to a region where the central position of the horizontal plane is located.
Whereas the second pole piece portion 12 being located in an outer region may refer to other regions than the central region, for example: the second pole piece portion 12 may be disposed around the first pole piece portion 11.
In addition, the fold can be understood as: the number of folds of the first pole piece portion 11 and the second pole piece portion 12, the number of folds of the first pole piece portion 11 can be represented by m, and the number of folds of the second pole piece portion 12 can be represented by n, wherein the ratio of m to n is not limited herein, for example: as an alternative embodiment, n/m may range from 1/9 to 9/1, that is, the ratio of the number of folds of the first pole piece portion 11 and the second pole piece portion 12 ranges from 1/9 to 9/1. In this way, flexibility of the number of times of folding the first pole piece portion 11 and the second pole piece portion 12 is enhanced, and of course, the number of times of folding the first pole piece portion 11 and the second pole piece portion 12 may be determined according to design requirements.
As another alternative embodiment, referring to fig. 3, the battery cell is a laminated battery cell, the laminated battery cell includes a plurality of positive electrode plates 10, the plurality of positive electrode plates 10 includes a first positive electrode plate and a second positive electrode plate, the first positive electrode plate is a positive electrode plate located in a middle position of the plurality of positive electrode plates, the second positive electrode plate is a positive electrode plate located in an outer position of the plurality of positive electrode plates, and the first positive electrode plate includes a coating layer having a content of a metal element greater than a content of a metal element of a coating layer included in the second positive electrode plate.
In this way, because the metal element of the coating layer included by the first positive plate located in the middle of the positive plates 10 is greater than the metal element of the coating layer included by the second positive plate located in the outer position of the positive plates 10, the stability of the positive plates during charging and discharging can be better, and the cycle performance of the whole battery cell can be improved. Meanwhile, the diversity of the battery cell is also increased.
It should be noted that the external position may refer to a position other than the intermediate position.
As an alternative embodiment, the laminated cell comprises positive plates that include a coating that includes a decreasing content of metallic elements in a direction from the first positive plate to the second positive plate. That is, from the middle position of the battery cell to the external position of the battery cell, the content of the metal element of the coating included in the positive plate is reduced in a gradient manner, so that the stability of the battery cell during charging and discharging can be further enhanced. The specific value of the gradient is not limited herein.
In addition, as an optional embodiment, the battery cell is a laminated battery cell, the laminated battery cell includes a plurality of positive plates 10, the plurality of positive plates 10 include a first positive plate and a second positive plate, the first positive plate is a positive plate located at a middle position of the plurality of positive plates, the second positive plate is a positive plate located at an edge position of the plurality of positive plates, and a content of a metal element of a coating included in the first plate portion 11 of the first positive plate is greater than a content of a metal element of a coating included in the first plate portion 11 of the second positive plate. Therefore, the stability of the positive plate during charging and discharging can be further enhanced, and the cycle performance of the whole battery core is improved.
An embodiment of the present invention further provides a battery, including the battery cell in the foregoing embodiment, and because the battery provided in the embodiment of the present invention includes the battery cell in the foregoing embodiment, the battery has the same beneficial technical effects as the battery cell in the foregoing embodiment, and specific structures of the battery cell may refer to corresponding descriptions of the foregoing embodiment, which are not described herein again.
The invention is illustrated by the following specific examples.
The processing steps of the laminated battery core can be seen as the following steps:
step 401, mixing the positive electrode active material 1, the binder PVDF and the conductive agent according to a certain mass ratio (the specific value of the mass ratio is not limited herein, for example, the mass ratio can be 97.8: 1.1: 1.1), adding N-methyl pyrrolidone, stirring and dispersing to prepare positive electrode slurry 1 with appropriate solid content, coating the positive electrode slurry 1 on a current collector, and performing the procedures of drying, rolling, slitting, tabletting and the like to obtain a positive electrode sheet 1;
step 402, mixing the positive active material 2, the binder PVDF and the conductive agent according to a certain mass ratio (the specific value of the mass ratio is not limited herein, for example, the mass ratio can be 97.8: 1.1: 1.1), adding N-methylpyrrolidone, stirring and dispersing to prepare positive slurry 2 with a proper solid content, coating the positive slurry 2 on a current collector, and performing the procedures of drying, rolling, slitting, tabletting and the like to obtain a positive plate 2;
step 403, 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, and then preparing negative slurry by adjusting with water. And drying, rolling, slitting, sheet making and the like to obtain the negative plate.
And step 404, stacking the obtained positive plate and negative plate 20 together with the diaphragm 30, packaging the positive plate and negative plate into a battery core by using an aluminum plastic film, and finally testing the electrical property of the battery through the procedures of liquid injection, formation, secondary packaging, sorting, aging and the like.
The battery performance test may include two parameters of high temperature charge and discharge test and energy density, and the high temperature charge and discharge test may be referred to as the following expression: after being placed for 2 hours at the ambient temperature of 45 +/-2 ℃, the battery cell is charged and discharged: 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 5 min. The step is used for cycling, and the capacity retention rate of the battery in the charging and discharging cycle process is monitored.
The energy density may be a volume energy density, where (wh/L) is a table capacity (Ah) x a system plateau voltage (V)/a cell volume (L) at room temperature.
It should be noted that the performance of each example can be observed by adjusting the difference between the number of layers of the positive electrode sheet 1 and the positive electrode sheet 2, the content of aluminum, and the content of manganese. See table 1 for details.
TABLE 1
As can be seen from examples 1 to 3 in table 1, as the number of layers of the positive electrode sheet 1 increases, the retention rate at 300cls of the battery cycle gradually increases, and the corresponding energy density loss increases.
As can be seen from comparison of examples 1 to 3 and comparative example 1 in Table 1, the Al content in the positive electrode sheet 1 is increased, the cycle retention rate is improved, and the corresponding energy density is lost.
As can be seen from comparison between example 2 and example 4 in table 1, the Mg content in the positive electrode sheet 1 is increased, the cycle retention rate is improved, and the corresponding energy density is lost.
The processing steps of the winding type battery cell can be seen in the following steps:
step 501, mixing the positive electrode active substance 1, the binder PVDF and the conductive agent according to a certain mass ratio (the specific value of the mass ratio is not limited herein, for example, the mass ratio can be 97.8: 1.1: 1.1), adding N-methyl pyrrolidone, stirring and dispersing to prepare positive electrode slurry 1 with appropriate solid content, coating the positive electrode slurry 1 on a current collector, and performing the procedures of drying, rolling, slitting, tabletting and the like to obtain a positive electrode sheet 1;
502, mixing a positive electrode active substance 2, a binder PVDF and a conductive agent according to a certain mass ratio (the specific value of the mass ratio is not limited herein, for example, the mass ratio can be 97.8: 1.1: 1.1), adding N-methylpyrrolidone, stirring and dispersing to prepare a positive electrode slurry 2 with a proper solid content, coating the positive electrode slurry 2 on a current collector, and performing the procedures of drying, rolling, slitting, tabletting and the like to obtain a positive electrode sheet 2;
and 503, sequentially coating the slurry 1 and the slurry 2 on the positive electrode current collector, wherein the coating position of the slurry 1 is a region 1, and the coating position of the slurry 2 is a region 2. The area ratio of zone 1 to zone 2 was 1: 1. And drying, rolling, slitting, flaking and other processes to obtain the positive plate.
Step 504, 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 materials, and then adjusting with water to prepare negative slurry. And drying, rolling, slitting, sheet making and the like to obtain the negative plate.
And 505, winding the obtained positive plate and negative plate together with the diaphragm 30 into a winding core, packaging the winding core by using an aluminum plastic film, and finally carrying out electrical property test on the battery through the processes of liquid injection, formation, secondary packaging, sorting, aging and the like.
Also, the electrical property test can be referred to the corresponding expression of the laminated cell described above, and the number of folds, the content of aluminum element, and the content of magnesium element of the positive electrode plate region 1 (the region 1 of the present embodiment may refer to the first electrode plate portion 11) and the region 2 (the region 2 of the present embodiment may refer to the second electrode plate portion 12) can also be adjusted, and then the properties of each embodiment are observed. See table 1 for details.
TABLE 2
As can be seen from examples 5 to 7 in table 2, as the number of folds of the positive electrode sheet region 1 increases, the retention rate of 300cls of the battery cycle gradually increases, and the corresponding energy density loss increases.
As can be seen from comparison of examples 5 to 7 and comparative example 2 in Table 2, the Al content in the positive plate region 1 is increased, the cycle retention rate is improved, and the corresponding energy density is lost.
As can be seen from the comparison between example 6 and example 8 in table 2, the Mg content in the positive electrode sheet region 1 increases, the cycle retention rate is improved, and the corresponding energy density is lost.
Therefore, by combining tables 1 and 2, it can be seen that: in the embodiment of the invention, the content of the metal element in the positive plate (or the pole plate part) in the middle position of the battery is increased, so that the cycle performance of the lithium ion battery under high temperature and high voltage can be improved, and the energy density can be considered at the same time.
It should be noted that E1 in table 1 and E2 in table 2 may refer to the energy density in the corresponding comparative examples, and the specific values are not limited herein.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A battery cell, comprising: positive plate, negative pole piece and diaphragm, the diaphragm is located positive plate with between the negative pole piece, positive plate includes first pole piece portion and second pole piece portion, first pole piece portion is located the intermediate position of electric core, second pole piece portion is located the outside of first pole piece portion, the metallic element's of the coating that first pole piece portion includes content is greater than the metallic element's of the coating that second pole piece portion includes content, metallic element includes aluminium element and magnesium element.
2. The battery cell of claim 1, wherein the positive electrode sheet comprises a coating layer having an elemental aluminum content of 4000-9000 ppm.
3. The battery cell of claim 1, wherein the positive electrode sheet comprises a coating layer containing magnesium in an amount of 500-3000 ppm.
4. The cell of any of claims 1 to 3, wherein the cell is a wound cell, and the first pole piece portion comprises a central region of the wound cell and the second pole piece portion comprises an outer region adjacent to the central region.
5. The cell of claim 4, wherein a ratio of the number of folds of the first pole piece portion and the second pole piece portion ranges from 1/9 to 9/1.
6. The electric core according to any of claims 1 to 3, wherein the electric core is a laminated electric core comprising a plurality of positive plates, the plurality of positive plates comprises a first positive plate and a second positive plate, the first positive plate is a positive plate located at a middle position of the plurality of positive plates, the second positive plate is a positive plate located at an outer position of the plurality of positive plates, and the first positive plate comprises a coating with a metal element content greater than that of the coating comprising the second positive plate.
7. The cell of claim 6, wherein the laminated cell comprises positive plates that comprise a coating that comprises a decreasing content of metallic elements in a direction from the first positive plate to the second positive plate.
8. The battery cell of claim 1, wherein the first pole piece portion comprises a coating with an aluminum content of 6000-9000ppm, and the second pole piece portion comprises a coating with an aluminum content of 5000-8000 ppm.
9. The battery cell of claim 1, wherein the first pole piece portion comprises a coating with a magnesium content of 1000-3000ppm, and the second pole piece portion comprises a coating with a magnesium content of 500-2000 ppm.
10. A battery comprising the cell of any one of claims 1 to 9.
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| CN202110585395.6A CN113314697A (en) | 2021-05-27 | 2021-05-27 | Battery core and battery |
| PCT/CN2022/093279 WO2022247687A1 (en) | 2021-05-27 | 2022-05-17 | Cell and battery |
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| WO2022247687A1 (en) * | 2021-05-27 | 2022-12-01 | 珠海冠宇电池股份有限公司 | Cell and battery |
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