CN213340472U - Roll core, battery and electronic product - Google Patents

Roll core, battery and electronic product Download PDF

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Publication number
CN213340472U
CN213340472U CN202022616080.7U CN202022616080U CN213340472U CN 213340472 U CN213340472 U CN 213340472U CN 202022616080 U CN202022616080 U CN 202022616080U CN 213340472 U CN213340472 U CN 213340472U
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negative
region
coating
positive
fold
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余正发
彭冲
胡贤飞
宋博
李俊义
徐延铭
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

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Abstract

The embodiment of the utility model provides a winding core, a battery and an electronic product, wherein the winding core comprises a positive plate, a negative plate and a diaphragm; the negative plate, the diaphragm, the positive plate and the diaphragm are stacked together and wound from the head to the tail; the negative plate comprises a negative current collector and a negative coating, the negative current collector comprises a first surface and a second surface which are oppositely arranged, and the negative coating is coated on the first surface only at the head part of the negative current collector to form a single-sided coating area; the single-sided coated region is folded in half such that the second surface of the first fold of the single-sided coated region is in electrical contact with the second surface of the second fold of the single-sided coated region. The utility model also provides a battery, including shell and the aforesaid book core. The utility model also provides an electronic product, including above-mentioned battery. The utility model provides a roll up core, at quick charge's in-process, can alleviate the excessive lithium that leads to of single face coating zone current density of the inside negative plate of roll core, promote the quick charge performance of battery.

Description

Roll core, battery and electronic product
Technical Field
The embodiment of the utility model provides a relate to lithium ion battery technique, especially relate to a roll up core, battery and electronic product.
Background
With the development of science and technology, more and more electronic products enter people's lives, and a large part of electronic products are driven by batteries. Among them, lithium ion batteries are widely used in electronic products in various fields because of their advantages such as long service life and high energy density.
The positive plate comprises a positive current collector and a positive coating coated on the surface of the positive current collector, and the negative plate comprises a negative current collector and a negative coating coated on the surface of the negative current collector. At present, in the manufacturing of a winding type lithium ion battery, after pole pieces are stacked together according to the order of a diaphragm, a negative pole piece, a diaphragm and a positive pole piece, a winding core is formed by winding from the head to the tail of the negative pole piece by taking the head of the negative pole piece as the center. The winding core formed in this way may have bent sections of the negative electrode sheets facing each other at the middle portion thereof, resulting in a decrease in energy density of the winding core. In order to improve the energy density of the winding core, a single-surface area is arranged at the head of the negative plate, namely, a negative coating is coated on only one surface of the position, opposite to the negative plate, of the negative plate in the middle of the winding core, so that the negative coating in the middle of the winding core is arranged opposite to the head of the negative plate.
However, in the charging process of the winding core, the current density of the single surface area of the negative electrode sheet is greater than that of the double surface areas of the negative electrode sheet, so that lithium precipitation is more likely to occur in the single surface area of the negative electrode sheet during large-current charging, and the quick charging performance of the battery is affected.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a roll up core, battery and electronic product to solve current roll up core at the in-process that charges, negative pole piece single face area current density is greater than negative pole piece double-sided district current density, and negative pole piece single face takes place easily when heavy current charging and separates lithium, influences the quick charge performance of battery.
According to an aspect of an embodiment of the present invention, there is provided a winding core, including a positive plate, a negative plate and a diaphragm;
the negative plate, the diaphragm, the positive plate and the diaphragm are stacked together and wound from the head to the tail, and the head of the negative plate is positioned inside the winding core;
the negative plate comprises a negative current collector and a negative coating, the negative current collector comprises a first surface and a second surface which are oppositely arranged, and the negative coating is coated on the first surface only at the head part of the negative current collector to form a single-surface coating area; the single-sided coating region is folded in half so that a second surface of the single-sided coating region first fold is opposite to a second surface of the single-sided coating region second fold; the second surface of the single-sided coated region first fold is in electrical contact with the second surface of the single-sided coated region second fold.
In an alternative implementation mode, the head part of the negative plate is further provided with an uncoated region, and the length of the uncoated region is smaller than the first folding length of the single-sided coated region. As can be appreciated by those skilled in the art, single-sided coating of the negative current collector is prone to the phenomenon of negative current collector wrinkling, and the uncoated region can impart resistance to the negative current collector, thereby mitigating negative current collector wrinkling.
In an alternative implementation, the single-sided coated region includes a first single-sided coated region located opposite the uncoated region and a second single-sided coated region located opposite the uncoated region, the head of the separator being located between the first single-sided coated region of the single-sided coated region in the first fold and the first single-sided coated region of the single-sided coated region in the second fold. As will be appreciated by those skilled in the art, positioning the head of the diaphragm between the first single-coated region of the first fold of the single-coated region and the first single-coated region of the second fold of the single-coated region prevents the diaphragm from completely separating the first fold from the second fold of the single-coated region, ensuring that the first fold and the second fold of the single-coated region are in electrical contact.
In an alternative implementation, the ratio of the length of the uncoated region to the first folded length of the single-sided coated region is from 0.1 to 1; the ratio of the length of the diaphragm between the first fold and the second fold of the single-sided coating region to the first fold length of the single-sided coating region is 0.1-0.5. It will be appreciated by those skilled in the art that when the ratio of the length of the uncoated region to the first fold length of the single-coated region is less than 0.1, the uncoated region does not provide a good barrier to wrinkling of the single-coated region; when the ratio of the length of the uncoated region to the first folded length of the single-sided coated region is greater than 1, the energy density of the core is reduced.
In an alternative implementation, the negative coating at the head of the single-sided coating region exceeds the positive coating at the head of the positive plate; the negative coating at the tail part of the negative plate exceeds the positive coating at the tail part of the positive plate. As can be understood by those skilled in the art, through the above arrangement, the negative electrode coating completely covers the positive electrode coating, and lithium ions precipitated from the positive electrode coating can be inserted into the negative electrode coating during the charging process of the winding core, so that the phenomenon of lithium precipitation of the negative electrode sheet is avoided.
In an optional implementation manner, the positive plate is provided with a positive tab, the positive tab is arranged in a tab connection area of the positive plate, and the positive tab is electrically connected with a positive current collector of the positive plate; the negative pole piece is equipped with the negative pole ear, the negative pole ear sets up the utmost point ear joining region of negative pole piece, the negative pole ear with negative pole mass flow body electricity is connected. As will be appreciated by those skilled in the art, the tab is a metal conductor that leads from the tab and the tab is a metal conductor that leads from the tab, and the tabs and tabs can be used to connect an external circuit to enable the roll core to be charged.
In an optional implementation manner, the positive tab and the negative tab are respectively located on two sides of a vertical central line of the winding core, the positive tab is located at the first fold of the positive plate, and the negative tab is located at the second fold of the single-sided coating region. Through the arrangement, the contact short circuit between the positive electrode lug and the negative electrode lug can be effectively avoided.
In an alternative implementation, the positive electrode coating of the first surface of the tail portion of the positive electrode sheet exceeds the positive electrode coating of the second surface of the tail portion of the positive electrode sheet, and the first surface of the tail portion of the positive electrode sheet faces the inside of the winding core. It will be appreciated by those skilled in the art that the above arrangement facilitates increasing the energy density of the core.
According to another aspect of the embodiments of the present invention, there is provided a battery, including a case and the winding core as described above.
According to another aspect of the embodiments of the present invention, there is provided an electronic product including the battery as described above.
As can be understood by those skilled in the art, the winding core of the present invention comprises a positive plate, a negative plate and a diaphragm, wherein the negative plate, the diaphragm, the positive plate and the diaphragm are stacked together and wound from the head to the tail, and the head of the negative plate is located inside the winding core. The negative plate comprises a negative current collector and a negative coating, the negative current collector comprises a first surface and a second surface which are oppositely arranged, and the head of the negative current collector is coated with the negative coating only on the first surface so as to form a single-side coating area on the head of the negative current collector. The single-sided coating region is folded in half such that the second surface of the first fold of the single-sided coating region is opposite the second surface of the second fold of the single-sided coating region. The second surface of the first fold of the single-sided coating region is in electrical contact with the second surface of the second fold of the single-sided coating region. Therefore, in the charging process of the winding core, the first folding part and the second folding part of the single-side coating area are approximately double-side coating areas, so that lithium precipitation caused by overlarge current density of the single-side coating area of the negative plate in the winding core can be relieved, and the quick charging performance of the battery is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.
Fig. 1 is a schematic structural diagram of a winding core provided by an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a positive plate provided by an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present invention.
Description of reference numerals:
100-roll core;
110-positive plate;
111-positive current collector;
112-positive electrode coating;
113-positive tab;
120-negative pole piece;
121-negative current collector;
122-negative electrode coating;
123-single facecoat region;
124-a first single facer coating zone;
125-a second single-sided coating region;
126-uncoated region;
127-negative tab;
130-membrane.
Detailed Description
First of all, it should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention. And can be modified as needed by those skilled in the art to suit particular applications.
Next, it should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "inside", "outside", and the like are based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that a device or member must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present invention.
At present, in the manufacture of a winding type lithium ion battery, a separator, a negative electrode sheet, a separator, and a positive electrode sheet are stacked in this order, and then a winding core is formed by winding from a head portion to a tail portion of the negative electrode sheet, with the head portion of the negative electrode sheet as a center. In order to improve the energy density of the winding core, a single-surface area is arranged at the head of the negative plate, namely, a negative coating is coated on only one surface of the position, opposite to the negative plate, of the negative plate in the middle of the winding core, so that the negative coating in the middle of the winding core is arranged opposite to the head of the negative plate. However, in the charging process of the winding core, the current density of the single surface area of the negative electrode sheet is greater than that of the double surface areas of the negative electrode sheet, so that lithium precipitation is more likely to occur in the single surface area of the negative electrode sheet during large-current charging, and the quick charging performance of the battery is affected.
Through repeated thinking and verification, the inventor finds that if the stacking sequence of the pole pieces is changed, no diaphragm is arranged below the negative pole piece, so that after the winding core is wound, the head single-side area of the negative pole piece is in electric contact, and the single-side area is approximately a double-side area after being in electric contact with the single-side area, thereby relieving the problem that the lithium separation caused by overlarge current density of the single-side coating area of the negative pole piece in the winding core improves the quick charging performance of the battery.
In view of the above, the inventor designs a winding core including a positive plate, a negative plate and a separator. The negative electrode sheet, the separator, the positive electrode sheet and the separator are stacked together and wound from the head to the tail so that the head of the negative electrode sheet is positioned inside the winding core. The negative plate comprises a negative current collector and a negative coating, the negative current collector comprises a first surface and a second surface which are oppositely arranged, and the negative coating is coated on the first surface only at the head part of the negative current collector to form a single-sided coating area; the single-sided coating area is folded in half, so that the second surface of the first fold of the single-sided coating area is opposite to the second surface of the second fold of the single-sided coating area; the second surface of the first fold of the single-sided coating region is in electrical contact with the second surface of the second fold of the single-sided coating region. Therefore, the first folding part and the second folding part of the single-side coating area are equivalent to the double-side coating area, so that lithium precipitation caused by overlarge current density of the single-side coating area can be relieved during the quick charging process of the winding core, and the quick charging performance of the battery is improved.
Example one
Fig. 1 is a schematic structural diagram of a winding core provided in this embodiment. As can be understood by those skilled in the art, the winding core 100 is a component for storing and releasing electric energy in the battery, and lithium ions are extracted from the positive plate 110 and embedded into the negative plate 120 during the charging process, and lithium ions are extracted from the negative plate 120 and embedded into the positive plate 110 during the discharging process, so that the charging and discharging of the winding core 100 are realized by the extraction of the lithium ions, and further, the charging and discharging of the lithium ion battery are realized. As shown in fig. 1, the winding core 100 provided by this embodiment includes a positive electrode tab 110, a negative electrode tab 120, and two separators 130, where the number of the separators 130 is two. Fig. 1 shows that the pole pieces are wound after being stacked together in the order of the negative electrode sheet 120, the separator 130, the positive electrode sheet 110, and the separator 130, and the head of the negative electrode sheet 120 is located inside the winding core 100 after the winding core 100 is completed.
Fig. 2 is a schematic structural diagram of the positive electrode sheet provided in this embodiment. As shown in fig. 2, the positive electrode sheet 110 includes a positive electrode collector 111 and a positive electrode coating 112, wherein the positive electrode coating 112 is coated on both the upper surface and the lower surface of the positive electrode collector 111. It will be understood by those skilled in the art that the positive coating 112 serves to provide sites for lithium ion intercalation and deintercalation, and in particular, lithium ion deintercalation from the positive coating 112 during charging of the jellyroll 100; during discharge of the jellyroll 100, lithium ions are intercalated into the positive electrode coating 112. The positive electrode coating 112 includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent. In this embodiment, specific components of the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are not limited, and those skilled in the art can set the specific components according to actual needs. Illustratively, LiCoO2, LiNiCoMnO2, LiCoAlO2, LiMn2O4, and the like can be used as the positive electrode active material.
Fig. 2 shows that the positive electrode tab 110 further includes a positive electrode tab 113, the positive electrode tab 113 is disposed at a tab connection region of the positive electrode tab 110 and the positive electrode tab 113 is electrically connected to the positive electrode collector 111 of the positive electrode tab 110. Illustratively, the material of the positive electrode tab 113 is the same as the material of the positive electrode collector 111, so as to achieve the electrical connection between the positive electrode tab 113 and the positive electrode collector 111. For example, when the positive electrode collector 111 is an aluminum foil, the material of the positive electrode tab 113 may be aluminum. In this embodiment, the connection manner between the positive tab 113 and the positive current collector 111 is not limited, and for example, the positive tab 113 is disposed on the positive current collector 111 by die cutting or bonding, and those skilled in the art can also make the positive tab 113 and the positive current collector 111 into an integral piece by an integral molding process.
As shown in fig. 1-2, the positive electrode sheet 110 is wound from left to right during winding, that is, the left side of the positive electrode sheet 110 is the head of the positive electrode sheet 110, and the right side of the positive electrode sheet 110 is the tail of the positive electrode sheet 110. The positive electrode coating 112 on the right upper surface of the positive electrode sheet 110 exceeds the positive electrode coating 112 on the right lower surface of the positive electrode sheet 110. Here, the upper surface of the positive electrode sheet 110 is defined as a first surface of the positive electrode sheet 110, and the lower surface of the positive electrode sheet 110 is defined as a second surface of the positive electrode sheet 110. The first surface of the tail of the positive electrode tab 110 faces the inside of the winding core 100. As can be understood by those skilled in the art, the outermost side of the winding core 100 is the positive electrode sheet 110, and if the positive electrode coating 112 is disposed in front of and behind two surfaces of the positive electrode sheet 110, the positive electrode coating 112 on the outermost side of the winding core 100 does not have the negative electrode coating 122 corresponding thereto, in other words, the first surface length of the positive electrode coating 112 at the tail of the positive electrode sheet 110 exceeds the second surface length of the tail of the positive electrode sheet 110 and the first surface of the tail of the positive electrode sheet 110 faces the inside of the winding core 100, so that the positive electrode coatings 112 all have the negative electrode coating 122 opposite to the positions thereof, which is beneficial for increasing the energy density of the winding core 100. It is easily understood that the portion of the first surface of the tail portion of the positive electrode sheet 110 to which the positive electrode coating 112 is applied, which exceeds the second surface of the tail portion of the positive electrode sheet 110 to which the positive electrode coating 112 is applied, is equal to the length of the outermost two-fold of the winding core 100. The specific length of the positive electrode coating 112 on the first surface of the positive electrode sheet 110 exceeding the positive electrode coating 112 on the second surface of the positive electrode sheet 110 is not limited in this embodiment, and can be determined by the skilled person according to the number of winding turns of the winding core 100.
Fig. 3 is a schematic structural diagram of the negative electrode sheet provided in this embodiment. As shown in fig. 1 and fig. 3, the negative electrode tab 120 includes a negative electrode collector 121 and a negative electrode coating 122, the negative electrode collector 121 includes a first surface and a second surface that are oppositely disposed, and exemplarily, an upper surface of the negative electrode collector 121 is the first surface of the negative electrode collector 121, and a lower surface of the negative electrode collector 121 is the second surface of the negative electrode collector 121. The negative electrode coating 122 is coated on only the first surface of the head of the negative electrode collector 121 to form a single-sided coated region 123, and the right side of the single-sided coated region 123 of the negative electrode sheet 120 is a double-sided coated region of the negative electrode sheet 120. Fig. 1 shows that the single-sided coating area 123 of the negative electrode sheet 120 is folded in half so that the first folded second surface of the single-sided coating area 123 is opposite to the second folded second surface of the single-sided coating area 123. it is easy to understand that after the winding core 100 is wound, the first folded second surface of the single-sided coating area 123 of the negative electrode sheet 120 and the second folded second surface of the single-sided coating area 123 of the negative electrode sheet 120 are partially in contact with each other, that is, the first folded second surface of the single-sided coating area 123 of the negative electrode sheet 120 and the second folded second surface of the single-sided coating area 123 of the negative electrode sheet 120 are electrically contacted with each other when the winding core 100 is in an energized.
It will be readily appreciated that the negative electrode coating 122 also serves to provide sites for lithium ion intercalation and deintercalation, and in particular, lithium ions are intercalated into the negative electrode coating 122 during battery charging and lithium ions are deintercalated from the negative electrode coating 122 during battery discharging. The negative electrode coating 122 includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The present embodiment is not limited to specific components of the anode active material, the anode conductive agent, and the anode binder, and those skilled in the art can set the components according to actual needs, and for example, graphite, hard carbon, silicon, silica, or the like can be used as the anode active material.
As can be understood by those skilled in the art, by making the second folded surface of the single-sided coating region 123 of the negative electrode sheet 120 electrically contact the second folded surface of the single-sided coating region 123 of the negative electrode sheet 120, the first folded and second folded portions of the single-sided coating region 123 are approximately double-sided coating regions, so that the lithium precipitation caused by the excessive current density of the single-sided coating region 123 of the negative electrode sheet 120 inside the winding core 100 can be alleviated, and the quick charging performance of the battery can be improved.
As shown in fig. 3, the head of the negative electrode tab 120 is further provided with an uncoated region 126, i.e., a region where both the upper surface and the lower surface of the negative electrode collector 121 are free of the negative electrode coating 122. The length of the uncoated region 126 is less than the first fold length of the single-sided coated region 123. As can be appreciated by those skilled in the art, the single-sided coating of the negative electrode current collector 121 is prone to a phenomenon of wrinkling of the negative electrode current collector 121, and the uncoated region 126 can apply resistance to the negative electrode current collector 121, thereby alleviating the wrinkling of the single-sided coated region 123 of the negative electrode sheet 120. The length of the uncoated region 126 is set to be smaller than the first folding length of the single-sided coated region 123 of the negative electrode sheet 120, so that the uncoated region 126 is prevented from being folded inside the winding core 100, and the energy density of the winding core 100 is improved.
Illustratively, the ratio of the length of the uncoated region 126 to the first folding length of the single-sided coated region 123 of the negative electrode sheet 120 is 0.1-1. When the ratio of the length of the uncoated region 126 to the first folding length of the single-side coated region 123 of the negative electrode sheet 120 is less than 0.1, the uncoated region 126 has less effect of preventing the single-side coated region 123 of the negative electrode sheet 120 from wrinkling; when the ratio of the length of the uncoated region 126 to the first folding length of the single-sided coated region 123 of the negative electrode sheet 120 is greater than 1, the uncoated region 126 may increase the weight of the winding core 100 too much, reducing the energy density of the winding core 100. The specific ratio of the lengths of the uncoated region 126 and the single-sided coated region 123 of the negative electrode sheet 120 can be set by those skilled in the art according to actual needs.
Fig. 3 shows that the negative electrode tab 120 is provided with the negative electrode tab 127, the negative electrode tab 127 is disposed at a tab connection region of the negative electrode tab 120, illustratively, the tab connection region of the negative electrode tab 120 is located at the single-sided coated region 123 of the negative electrode tab 120 and the tab connection region of the negative electrode tab 120 is an uncoated region on the negative electrode tab 120. The negative electrode tab 127 is electrically connected to the negative electrode current collector 121, and generally, the materials of the negative electrode tab 127 and the negative electrode current collector 121 may be set according to actual needs. For example, if a copper foil is used as the negative electrode collector 121, the material of the negative electrode tab 127 is nickel, and the negative electrode tab 127 and the negative electrode collector 121 are electrically connected. Negative tab 127 and negative current collector 121 may be connected by various methods, for example, by welding.
As can be understood by those skilled in the art, positive tab 113 is a metal conductor led out from positive tab 110, and negative tab 127 is a metal conductor led out from negative tab 120, that is, positive tab 113 and negative tab 127 may be used as contact points of winding core 100 with an external circuit during charging and discharging, or winding core 100 may be connected to the external circuit through positive tab 113 and negative tab 127 to realize charging and discharging of winding core 100.
As shown in fig. 1, positive tab 113 and negative tab 127 are preferably located on two sides of a vertical center line L1 of winding core 100, wherein the vertical center line is a center line extending in the up-down direction in fig. 1 and passing through the middle of the winding core. For example, positive tab 113 is located to the right of vertical center line L1 of winding core 100, and negative tab 127 is located to the left of vertical center line L1. One possible implementation is that positive tab 113 is positioned on the first fold of positive tab 110 and negative tab 127 is positioned on the second fold of single-sided coated region 123. As will be understood by those skilled in the art, disposing positive tab 113 and negative tab 127 on two sides of the vertical center line of winding core 100 can effectively avoid short circuit between positive tab 113 and negative tab 127.
As shown in fig. 1, the number of the separators 130 is two, and the specific positions of the separators 130 with respect to the positive electrode tab 110 and the negative electrode tab 120 are changed compared to the related art. In the prior art, the two separators 130 sandwich the negative electrode sheet 120 to insulate the negative electrode sheet 120 and the positive electrode sheet 110 from each other, while in the present embodiment, the two separators 130 sandwich the positive electrode sheet 110 to insulate the positive electrode sheet 110 and the negative electrode sheet 120 from each other. Compared with the prior art, in the embodiment, the electrical contact between the first fold of the single-sided coating area 123 of the negative electrode sheet 120 and the second fold of the single-sided coating area 123 of the negative electrode sheet 120 can be realized, so that the lithium precipitation caused by the overlarge current density of the single-sided coating area 123 of the negative electrode sheet 120 in the winding core 100 can be relieved.
As can be appreciated by those skilled in the art, the separator 130 can insulate the positive electrode tab 110 and the negative electrode tab 120 from each other, and prevent the winding core 100 from short-circuiting during charging and discharging. The diaphragm 130 is provided with a hole for lithium ions to pass through, so that the lithium ion battery with the winding core 100 can work normally.
Illustratively, the separator 130 may include a substrate, which may be a Polyethylene (PE) monolayer film, a polypropylene (PP) monolayer film, or a polypropylene-polyethylene-polypropylene three-layer composite film, and a coating layer, which may be at least one of porous silicon dioxide, aluminum oxide, titanium dioxide, and zirconium dioxide.
One possible implementation is that the single-coated region 123 of the negative electrode sheet 120 includes a first single-coated region 124 opposite the uncoated region 126 and a second single-coated region 125 not opposite the uncoated region 126, and the head of the separator 130 is located between the first single-coated region 124 of the first fold of the single-coated region 123 and the first single-coated region 124 of the second fold of the single-coated region 123. Illustratively, the head of the separator 130 is approximately aligned with the head of the negative electrode tab 120, so that the winding core 100 is easily clamped during winding. As can be appreciated by those skilled in the art, disposing the head of the separator 130 between the first single-coated region 124 of the first fold of the single-coated region 123 of the negative electrode sheet 120 and the first single-coated region 124 of the second fold of the single-coated region 123 of the negative electrode sheet 120 prevents the separator 130 from completely separating the first fold and the second fold of the single-coated region 123, and ensures that the first fold and the second fold of the single-coated region 123 are in partial electrical contact.
Illustratively, the ratio of the length of the diaphragm 130 between the first and second folds of the single-facecoat region 123 to the first fold length of the single-facecoat region 123 is 0.1 to 0.5. When the ratio of the length of the separator 130 between the first fold and the second fold of the single-sided coating region 123 to the first fold length of the single-sided coating region 123 is less than 0.1, if an error occurs during the stacking process of the positive electrode sheet 110, the negative electrode sheet 120, and the separator 130, the separator 130 cannot completely insulate the positive electrode coating 112 of the positive electrode sheet 110 from the negative electrode coating 122 of the negative electrode sheet 120; when the ratio of the length of the separator 130 between the first fold and the second fold of the single-sided coating region 123 to the first fold length of the single-sided coating region 123 is greater than 0.5, the electrical contact position between the second surface of the first fold of the single-sided coating region 123 of the negative electrode sheet 120 and the second surface of the second fold of the single-sided coating region 123 of the negative electrode sheet 120 is less, i.e., the lithium precipitation effect caused by the excessive current density of the single-sided coating region 123 of the negative electrode sheet 120 inside the winding core 100 is alleviated to be less.
It should be noted that, as shown in fig. 1, the negative coating 122 at the head of the single-side coating region 123 exceeds the positive coating 112 at the head of the positive plate 110, i.e., the negative coating 122 at the head of the negative plate 120 exceeds the positive coating 112 at the head of the positive plate 110; the negative coating 122 at the tail of the negative plate 120 exceeds the positive coating 112 at the tail of the positive plate 110. As can be understood by those skilled in the art, with the above arrangement, it can be ensured that the negative electrode coating 122 of the negative electrode sheet 120 completely covers the positive electrode coating 112 of the positive electrode sheet 110, and lithium ions extracted from the positive electrode coating 112 can be inserted into the negative electrode coating 122 during the charging process of the winding core 100, so as to avoid the phenomenon of lithium extraction from the negative electrode sheet 120.
Example two
On the basis of the first embodiment, the present embodiment further provides a battery, which includes the outer casing and the winding core in the first embodiment.
The battery that this embodiment provided is provided with book core and electrolyte in the inside of shell, and it includes positive plate, negative pole piece and diaphragm to roll up the core, and the core communicates with external circuit through the positive tab of positive plate and the negative pole ear of negative pole piece. Specifically, in the process of charging the battery, lithium ions are extracted from the positive coating of the positive plate and are embedded into the negative coating of the negative plate after passing through the diaphragm; in the discharging process of the battery, lithium ions are extracted from the negative electrode coating of the negative electrode plate, pass through the diaphragm and are embedded into the positive electrode coating of the positive electrode plate.
In the battery provided by the embodiment, because the winding core in the first embodiment is adopted, the current density of the negative electrode coating is the same in the charging process, the lithium precipitation of the negative electrode sheet is difficult to occur, and the quick charging performance is improved.
EXAMPLE III
The embodiment provides an electronic product, which comprises a battery.
The battery in this embodiment has the same structure as the battery provided in the second embodiment, and can bring about the same or similar technical effects, and details are not repeated herein, and reference may be specifically made to the description of the above embodiments.
In the description of the present invention, it is to be understood that the terms "top," "bottom," "upper," "lower" (if present), and the like, are used in the orientation or positional relationship shown in the drawings for convenience in describing the present invention and to simplify the description, and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The terms "first" and "second" in the description and claims of the present application and the description of the above-described figures are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. A winding core is characterized by comprising a positive plate, a negative plate and a diaphragm;
the negative plate, the diaphragm, the positive plate and the diaphragm are stacked together and wound from the head to the tail, and the head of the negative plate is positioned inside the winding core;
the negative plate comprises a negative current collector and a negative coating, the negative current collector comprises a first surface and a second surface which are oppositely arranged, and the negative coating is coated on the first surface only at the head part of the negative current collector to form a single-surface coating area; the single-sided coating region is folded in half so that a second surface of the single-sided coating region first fold is opposite to a second surface of the single-sided coating region second fold; the second surface of the single-sided coated region first fold is in electrical contact with the second surface of the single-sided coated region second fold.
2. The winding core according to claim 1, wherein the head of the negative electrode sheet is further provided with an uncoated region having a length less than the first fold length of the single-sided coated region.
3. The winding core of claim 2 wherein the single facer region comprises a first single facer region opposite the uncoated region and a second single facer region opposite the uncoated region, the separator membrane head being positioned between the first single facer region of the single facer region in the first fold and the first single facer region of the single facer region in the second fold.
4. The winding core of claim 3 wherein the ratio of the length of the uncoated region to the first folded length of the single-sided coated region is from 0.1 to 1; the ratio of the length of the diaphragm between the first fold and the second fold of the single-sided coating region to the first fold length of the single-sided coating region is 0.1-0.5.
5. The winding core according to any of claims 1-4, characterized in that the negative coating at the head of the single-sided coating zone exceeds the positive coating at the head of the positive electrode sheet; the negative coating at the tail part of the negative plate exceeds the positive coating at the tail part of the positive plate.
6. The winding core according to any one of claims 1 to 4, characterized in that the positive plate is provided with a positive tab, the positive tab is arranged on a tab connection area of the positive plate, and the positive tab is electrically connected with a positive current collector of the positive plate; the negative pole piece is equipped with the negative pole ear, the negative pole ear sets up the utmost point ear joining region of negative pole piece, the negative pole ear with negative pole mass flow body electricity is connected.
7. The winding core according to claim 6, wherein the positive tab and the negative tab are respectively positioned on two sides of a vertical central line of the winding core, the positive tab is positioned on a first fold of the positive tab, and the negative tab is positioned on a second fold of the single-sided coating area.
8. The winding core according to any one of claims 1 to 4, characterized in that the positive electrode coating of the first surface of the tail portion of the positive electrode tab exceeds the positive electrode coating of the second surface of the tail portion of the positive electrode tab, the first surface of the tail portion of the positive electrode tab facing the inside of the winding core.
9. A battery comprising a can and a jellyroll of any of claims 1-8.
10. An electronic product comprising the battery according to claim 9.
CN202022616080.7U 2020-11-12 2020-11-12 Roll core, battery and electronic product Active CN213340472U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113421994A (en) * 2021-06-18 2021-09-21 东莞新能安科技有限公司 Electrochemical device and electronic device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113421994A (en) * 2021-06-18 2021-09-21 东莞新能安科技有限公司 Electrochemical device and electronic device
CN113421994B (en) * 2021-06-18 2022-11-29 东莞新能安科技有限公司 Electrochemical device and electronic device

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