CN112750974A - Lithium battery positive plate, winding type battery cell and lithium ion battery - Google Patents
Lithium battery positive plate, winding type battery cell and lithium ion battery Download PDFInfo
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
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- 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
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- 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
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- 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
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Abstract
The invention relates to a lithium battery positive plate, a winding type battery cell and a lithium battery, wherein the positive plate comprises a positive current collector and a functional layer coated on at least one surface of the positive current collector, a positive pole lug is arranged on a first surface of the positive current collector, the functional layer on a second surface opposite to the first surface comprises a double-layer coating area close to the positive pole lug, the double-layer coating area comprises a first positive active material layer and a second positive active material layer, the first positive active material layer is positioned between the surface of the positive current collector and the second positive active material layer, the solid phase diffusion coefficient of lithium in a first positive active material in the first positive active material layer is larger than that of lithium in a second positive active material in the second positive active material layer, and the lithium precipitation phenomenon of a lithium battery negative pole can be well inhibited.
Description
Technical Field
The invention relates to the field of lithium batteries, in particular to a lithium battery positive plate, a winding type battery cell and a lithium ion battery.
Background
The lithium ion battery has the advantages of high working voltage, high energy density, long cycle life, environmental friendliness and the like, and is widely applied to the fields of 3C digital products, electric automobiles, military aerospace and the like. With the popularization and application of intelligent digital products and the wide application of new energy automobiles, the requirements for shortening the charging time of the lithium ion battery and improving the energy density of the lithium ion battery become more urgent, and correspondingly higher requirements for the charging speed and the charging voltage of the lithium ion battery are provided.
Most of batteries used in the existing digital products adopt a winding structure, and the requirements of high energy density and high charging speed are often met. However, after the battery is charged and discharged for a certain number of times, the lithium separation phenomenon is easy to occur in the region of the negative plate adjacent to the tab, and the lithium separation is more serious when the charging current is larger. Lithium precipitated from the negative electrode forms dendrite, the dendrite is easy to pierce through a diaphragm to cause short circuit of the battery, the battery is caused to smoke, fire and even explode, and the potential safety hazard is serious, so that the lithium precipitation from the negative electrode is required to be inhibited, and the safety of the battery is ensured.
In the existing lithium ion battery manufacturing technology, slurry with the same formula is adopted for the whole coating of the pole piece, the types, the contents and the coating thicknesses of active substances in all regions in the length direction of the pole piece are kept consistent, and the lithium precipitation phenomenon is easily caused in the region of the cathode piece adjacent to the pole lug.
Therefore, optimizing the composition structure of the positive plate of the lithium battery can better inhibit the lithium precipitation of the negative electrode, thereby being capable of adapting to larger charging current, having higher charging speed and longer service life, and is an important problem to be solved by technical personnel in the field.
Disclosure of Invention
The invention aims to provide a lithium battery positive plate which can better inhibit the lithium precipitation phenomenon of a lithium battery negative electrode.
The invention also provides a winding type battery cell comprising the lithium battery positive plate and a lithium ion battery comprising the winding type battery cell, and the lithium ion battery assembled by the battery cell can better inhibit the lithium precipitation phenomenon of the lithium battery negative electrode and has better cycle performance.
In one aspect of the invention, a lithium battery positive plate is provided, which comprises a positive current collector and a functional layer coated on at least one surface of the positive current collector, wherein a positive electrode tab is arranged on a first surface of the positive current collector, the functional layer on a second surface opposite to the first surface comprises a double-layer coating area close to the positive electrode tab, the double-layer coating area comprises a first positive electrode active material layer and a second positive electrode active material layer, the first positive electrode active material layer is positioned between the surface of the positive current collector and the second positive electrode active material layer, and the solid-phase diffusion coefficient of lithium in a first positive electrode active material in the first positive electrode active material layer is greater than the solid-phase diffusion coefficient of lithium in the second positive electrode active material.
The invention provides the positive plate with continuous active material coating and segmented dynamic performance by controlling the solid-phase diffusion coefficient of lithium in the positive active materials in the first positive active material layer and the second positive active material layer and changing the structure of the positive plate, so as to inhibit the lithium removal performance of the negative plate, make lithium separation more difficult, and solve the problem of lithium separation of the negative plate in the rapid charge-discharge cycle process of the lithium ion battery at present.
According to the research of the invention, the ratio of the solid phase diffusion coefficient of the positive electrode active material in the first positive electrode active material layer to the solid phase diffusion coefficient of the positive electrode active material in the second positive electrode active material layer is generally not less than 1.2, and further can be 1.2-1000, which is beneficial to inhibiting the lithium removal performance of the negative electrode sheet.
In one embodiment of the present invention, the solid phase diffusion coefficient of lithium in the first positive electrode active material may be 10-16-10-9The solid phase diffusion coefficient of lithium in the second positive electrode active material may be 10-16-10-9。
According to the research of the invention, the first positive active material and the second positive active material can be at least one of lithium cobaltate, a nickel-cobalt-manganese ternary material, a nickel-cobalt-aluminum ternary material and lithium iron phosphate, and in specific implementation, the positive active material with the target lithium solid-phase diffusion coefficient can be selected by screening the lithium in the positive active material through testing the solid-phase diffusion coefficient of the lithium. For example, both the first positive electrode active material and the second positive electrode active material may be lithium cobaltate, but they are lithium cobaltate having different lithium solid phase diffusion coefficients.
In an embodiment of the present invention, the lengths of the first positive active material layer and the second positive active material layer in the positive electrode sheet of the lithium battery may be generally set according to the length of the region adjacent to the negative electrode tab where lithium deposition is easy, for example, when the positive electrode sheet is used for manufacturing a winding type battery cell, the lengths of the first positive active material layer and the second positive active material layer in the positive electrode sheet are L203, the length of the second positive active material layer is L204, the winding core width is W, and the lengths of the first positive active material layer and the second positive active material layer and the winding core width satisfy the following conditions: l203 is more than or equal to 0.5W and less than or equal to 3W, and L204 is more than or equal to 0.5W and less than or equal to 3W. According to the research of the invention, in the winding type battery cell, the lithium is easily separated from the negative plate in the 0.5W-3W area adjacent to the negative pole tab, so that the lithium separation phenomenon of the negative pole of the lithium battery in the rapid charging and discharging process can be better inhibited by adjusting the pole plate structure of the positive plate in the corresponding area.
In a preferred embodiment of the present invention, the length of the first positive electrode active material layer and the length of the second positive electrode active material layer may be equal.
In a preferred embodiment of the present invention, the distance between the first positive electrode active material layer and the current collector end point on the side close to the positive electrode tab is equal to the distance between the second positive electrode active material layer and the current collector end point on the side close to the positive electrode tab, that is, when the slurry forming the first positive electrode active material layer and the slurry forming the second positive electrode active material layer are both coated from the side close to the positive electrode tab at the time of preparing the positive electrode sheet, the coating starting points of the two layers are the same; when the slurry forming the first positive electrode active material layer and the slurry forming the second positive electrode active material layer are both coated from the side away from the positive electrode tab, the coating end points of the two layers are the same.
In one embodiment of the present invention, the raw material of the first cathode active material layer may include: 70-99 wt% of first positive electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder, and the raw material of the second positive electrode active material layer may include: 70-99 wt% of second positive electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder.
In a preferred embodiment of the present invention, the raw materials of the first positive electrode active material layer may generally include: 80-98 wt% of a first positive electrode active material, 1-10 wt% of a conductive agent and 1-10 wt% of a binder, and the raw material of the second negative electrode active material layer may generally include: 80-98 wt% of second positive electrode active material, 1-10 wt% of conductive agent and 1-10 wt% of binder.
The lithium battery positive plate can be prepared by the following steps: and sequentially coating first positive active material layer slurry and second positive active material layer slurry in an area, close to the positive electrode lug, of a second surface, opposite to the positive electrode lug, of the positive current collector to form a first positive active material layer and a second positive active material layer, wherein the first positive active material layer and the second positive active material layer form a functional layer of the positive plate of the lithium battery. Wherein solid contents of the slurry forming the first cathode active material layer and the slurry forming the second cathode active material layer may be 40 wt% to 45 wt%.
In an embodiment of the present invention, the functional layer of the positive electrode sheet of the lithium battery further includes a first normal coating region that is far away from the positive electrode tab and connected to the double-layer coating region, the first normal coating region is formed by a single layer of a third positive electrode active material layer, and a sum of a unit area capacity of the first positive electrode active material layer and a unit area capacity of the second positive electrode active material layer is not less than a unit area capacity of the third positive electrode active material layer, so that the positive electrode sheet has higher consistency and the lithium deposition phenomenon of the negative electrode sheet is better inhibited.
It can be understood that after the double-layer coating area is coated according to the research of the invention, the single-layer coating is adopted for the first normal coating area connected with the double-layer coating area, which is beneficial to reducing the processing procedures of the positive plate and saving the processing time.
In one embodiment of the present invention, the raw material of the third cathode active material layer may include: 70-99 wt% of third positive electrode active material, 0.5-15 wt% of conductive agent and 0.5-15 wt% of binder, preferably, 80-98 wt% of third positive electrode active material, 1-10 wt% of conductive agent and 1-10 wt% of binder.
The solid phase diffusion coefficient of lithium in the third positive electrode active material may be the same as or different from that of the first positive electrode active material and the second positive electrode active material, and the present invention is not particularly limited thereto.
The third positive electrode active material may include at least one of lithium cobaltate, a nickel-cobalt-manganese ternary material, a nickel-cobalt-aluminum ternary material, and lithium iron phosphate.
The conductive agent and the binder in the raw materials of the first positive electrode active material layer, the second positive electrode active material layer and the third positive electrode active material layer can be the same or different, and the conductive agent can comprise at least one of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nano tube, metal powder and carbon fiber; the binder may include at least one of sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.
The lithium battery positive plate can be prepared by the following steps: sequentially coating first positive active material layer slurry and second positive active material layer slurry on a second surface, opposite to the lug, of the positive current collector in a region close to the positive lug to form a first positive active material layer and a second positive active material layer, wherein the first positive active material layer and the second positive active material layer form a double-layer coating region; coating a third positive active material layer on the area which is far away from the positive electrode lug and is connected with the double-layer coating area to form a first normal coating area; the double-layer coating area and the first normal coating area form a functional layer of the positive plate of the lithium battery. Wherein solid contents of the slurry forming the first cathode active material layer, the slurry forming the second cathode active material layer, and the slurry forming the third cathode active material layer may be 40 wt% to 45 wt%.
According to the research of the invention, the thickness of the first positive active material layer in the positive plate is T203, the thickness of the second positive active material layer is T204, the thickness of the third positive active material layer is T205, T203 is more than or equal to 10 microns and less than or equal to 60 microns, T204 is more than or equal to 10 microns and less than or equal to 60 microns, T203-T204 is more than or equal to 50 microns, T203+ T204-T205 is more than or equal to 3 microns and less than or equal to 6 microns, so that the positive plate with more uniform thickness can be obtained, and the positive plate can be prevented from being broken in the rolling process.
Generally, there is also a non-functional layer coated area on the positive current collector (denoted as positive current collector empty area).
In an embodiment of the present invention, both surfaces of the positive electrode current collector are coated with a functional layer, and the functional layer on the first surface opposite to the second surface includes a second normal coating region mirror-symmetrical to the double-coated region and the first normal coating region, and the second normal coating region is formed by a single layer of the third positive electrode active material layer, which is beneficial to improving the energy density of the positive electrode sheet.
In another aspect of the invention, a winding type battery cell is provided, which comprises the above lithium battery positive plate.
In an embodiment of the invention, in the winding cell, the length of the first positive electrode active material layer in the positive electrode sheet is L203, the length of the second positive electrode active material layer is L204, the width of the winding core is W, 0.5W ≤ L203 ≤ 3W, and 0.5W ≤ L204 ≤ 3W.
In another aspect of the present invention, a lithium ion battery is provided, which includes the above-mentioned winding type battery cell.
The embodiment of the invention has at least the following beneficial effects:
the lithium battery positive plate provided by the invention has better performance of inhibiting the lithium removal of the negative plate, and can better inhibit the lithium precipitation phenomenon of the negative electrode of the lithium battery when being applied to the lithium battery, thereby improving the comprehensive performances of the battery, such as cycling stability, safety and the like; the capacity retention rate of the lithium battery obtained by assembling the lithium battery can reach 90 percent after the lithium battery is cycled for 500 times, and even is higher than 95 percent.
The winding type battery cell comprising the lithium battery positive plate and the lithium ion battery comprising the winding type battery cell have good capability of inhibiting lithium precipitation of the lithium battery negative electrode, and can improve the safety and the cycling stability of the battery.
Drawings
Fig. 1 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of a positive plate according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a wound battery cell according to an embodiment of the invention.
Description of reference numerals:
101. a negative electrode tab; 102. a negative current collector; 103. a negative electrode active material layer; 201. a positive electrode tab; 202. a positive current collector; 203. a first positive electrode active material layer; 204. a second positive electrode active material layer; 205. and a third positive electrode active material layer.
Detailed Description
In order that those skilled in the art will better understand the concept of the present invention, the following detailed description is given with reference to the accompanying drawings.
As shown in fig. 3, the present invention provides a winding type battery cell, which includes a negative electrode sheet and a positive electrode sheet, wherein the negative electrode sheet has a structure as shown in fig. 1, and includes a negative electrode current collector 102 and a functional layer coated on the negative electrode current collector 102, and the functional layer is formed by a positive electrode active material layer 103.
The structure of the positive plate is shown in fig. 2, and the positive plate comprises a positive current collector 202 and a functional layer coated on at least one surface of the positive current collector 202, wherein a positive tab 201 is arranged on a first surface of the positive current collector, the functional layer on a second surface opposite to the first surface comprises a double-layer coating area close to the positive tab 201, the double-layer coating area comprises a first positive active material layer 203 and a second positive active material layer 204, the first positive active material layer 203 is positioned between the surface of the positive current collector 202 and the second positive active material layer 204, the functional layer further comprises a first normal coating area which is far away from the positive tab 201 and connected with the double-layer coating area, and the first normal coating area is formed by a single-layer third positive active material layer 205; both surfaces of the positive current collector are coated with functional layers, and the functional layer of the first surface opposite to the second surface includes a second normal coating region mirror-symmetrical to the double-coated region and the first normal coating region, the second normal coating region being formed of a single layer of the third positive active material layer 205.
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the implementation of the present invention will be clearly and completely described below with reference to the examples and comparative examples of the present invention, and it is obvious that the described examples are a part of the examples of the present invention, but not all of the examples. 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.
Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, instruments and the like used in the following examples and comparative examples are all conventional reagents, conventional materials and conventional instruments.
Example 1
Preparing a negative plate: 97 wt% of graphite (solid phase diffusion coefficient is 10)-14) Preparing positive active material layer slurry (solid content is 40 wt% -45 wt%) by 1 wt% of conductive carbon black and 2 wt% of styrene butadiene rubber, coating the slurry on a negative current collector by using a coating machine, and drying and rolling to obtain a negative plate, wherein the structure of the negative plate is shown in figure 1.
Preparing a positive plate: respectively preparing slurry for forming a first positive electrode active material layer, slurry for forming a second positive electrode active material layer and slurry for forming a third positive electrode active material layer; wherein the slurry composition of the first positive electrode active material layer is: 96 wt% of lithium cobaltate, 2 wt% of conductive carbon black and 2 wt% of polyvinylidene fluoride, wherein the solid content of the lithium cobaltate, the conductive carbon black and the polyvinylidene fluoride is 40-45 wt%; the slurry composition of the second positive electrode active material layer was: 96 wt% of lithium cobaltate, 2 wt% of conductive carbon black and 2 wt% of polyvinylidene fluoride, wherein the solid content of the lithium cobaltate, the conductive carbon black and the polyvinylidene fluoride is 40-45 wt%; the slurry composition of the third positive electrode active material layer was: 96 wt% of lithium cobaltate, 2 wt% of conductive carbon black and 2 wt% of polyvinylidene fluoride, and the solid content is 40-45 wt%. The solid-phase diffusion coefficient of lithium in the first positive electrode active material in the slurry for forming the first positive electrode active material layer (denoted by D203), the solid-phase diffusion coefficient of lithium in the second positive electrode active material in the slurry for forming the second positive electrode active material layer (denoted by D204), and the solid-phase diffusion coefficient of lithium in the third positive electrode active material in the slurry for forming the third positive electrode active material layer (denoted by D205) are shown in table 1.
The slurry prepared in the above manner is sequentially coated on a positive electrode current collector to form a first positive electrode active material layer, a second positive electrode active material layer and a third positive electrode active material layer, and the positive electrode sheet is obtained by drying and rolling, and the structure of the positive electrode sheet is shown in fig. 2, wherein the length of the positive electrode current collector is 1018mm, the length of the vacant region of the positive electrode current collector along the length direction of the negative electrode current collector is 50mm, the length of the first positive electrode active material layer (L203) is equal to the length of the second positive electrode active material layer (L204), and the length of the double-layer coating region formed by the first positive electrode active material layer and the second positive electrode active material layer is denoted as L2034. The bi-layer coating region length (L2034), the length of the third positive active material layer (L205), the first positive active material layer thickness (T203), the second positive active material layer thickness (T204), and the third positive active material layer thickness (T205) are shown in table 1.
Assembling the battery cell: and (3) winding the prepared negative plate, the positive plate and the diaphragm together to form a winding core (the width is 62mm), packaging by using an aluminum plastic film, baking to remove moisture, injecting electrolyte, and performing hot pressing to obtain the battery core.
Examples 2 to 7 and comparative examples 1 to 4
Examples 2 to 7 and comparative examples 1 to 4 were the same as in the preparation step of example 1, except that the solid phase diffusion coefficient of lithium in the first cathode active material in the slurry for forming the first cathode active material layer (D203), the solid phase diffusion coefficient of lithium in the second cathode active material in the slurry for forming the second cathode active material layer (D204), and the solid phase diffusion coefficient of lithium in the third cathode active material in the slurry for forming the third cathode active material layer (D205) were as shown in table 1.
The bi-layer coating region length (L2034), the length of the third positive active material layer (L205), the first positive active material layer thickness (T203), the second positive active material layer thickness (T204), and the third positive active material layer thickness (T205) are shown in table 1.
TABLE 1
Test example
The cells obtained in examples 1 to 7 and comparative examples 1 to 4 were assembled into lithium ion batteries, and the battery capacity and the capacity retention rate after 500 cycles were tested and the phenomenon of lithium precipitation at the negative electrode was observed, wherein the test was performed under the conditions of 2C charging and 0.7C discharging, and the test results are shown in table 2.
TABLE 2
| Capacity of battery | Number of cycles | Capacity retention rate | Whether or not to separate out lithium | |
| Example 1 | 3920mAh | 500 | 91.8％ | No occurrence of lithium precipitation |
| Example 2 | 3560mAh | 500 | 95.2％ | No occurrence of lithium precipitation |
| Example 3 | 3800mAh | 500 | 91.7％ | No occurrence of lithium precipitation |
| Example 4 | 3750mAh | 500 | 94.2％ | No occurrence of lithium precipitation |
| Example 5 | 3940mAh | 500 | 91.6％ | No occurrence of lithium precipitation |
| Example 6 | 3940mAh | 500 | 94.8％ | No occurrence of lithium precipitation |
| Example 7 | 3940mAh | 500 | 90.3％ | No occurrence of lithium precipitation |
| Comparative example 1 | 3940mAh | 500 | 83.8％ | Separating lithium |
| Comparative example 2 | 3940mAh | 500 | 84.9％ | Separating lithium |
| Comparative example 3 | 3940mAh | 500 | 80.2％ | Severe lithium precipitation |
| Comparative example 4 | 3940mAh | 500 | 86.5％ | Slight precipitation of lithium |
As can be seen from the test results in table 2, the lithium ion batteries assembled in examples 1 to 7 can effectively inhibit the lithium precipitation phenomenon of the negative electrode of the lithium battery, compared with the lithium ion batteries assembled in comparative examples 1 to 4, and have a higher capacity retention rate, and the capacity retention rate of the lithium battery assembled in examples after 500 cycles can reach 90%, even higher than 95%.
Finally, it should be noted that: the above experimental examples are only used to illustrate the technical solution of the present invention, but not to limit the same; although the present invention has been described in detail with reference to the foregoing experimental examples, it will be understood by those skilled in the art that: the technical scheme recorded in each experimental example can be modified, or part or all of the technical features can be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical scheme depart from the scope of the technical scheme of each experimental example of the invention.
Claims (10)
1. The utility model provides a lithium battery positive plate, its characterized in that includes the anodal mass flow body and coats the functional layer on the anodal mass flow body at least one surface, be equipped with anodal utmost point ear on the first surface of the anodal mass flow body, with the functional layer on the relative second surface of first surface is including the double-deck coating district near anodal utmost point ear, double-deck coating district includes first anodal active material layer and second anodal active material layer, first anodal active material layer is located between anodal mass flow surface and the second anodal active material layer, the solid phase diffusion coefficient of lithium is greater than the solid phase diffusion coefficient of lithium in the second anodal active material in the first anodal active material layer.
2. The positive electrode sheet for a lithium battery as claimed in claim 1, wherein the ratio of the solid phase diffusion coefficient of lithium in the first positive electrode active material to the solid phase diffusion coefficient of lithium in the second positive electrode active material is not less than 1.2.
3. The positive electrode sheet for lithium batteries according to claim 1 or 2, wherein the solid phase diffusion coefficient of lithium in the first positive electrode active material is 10-16-10-9And the solid phase diffusion coefficient of lithium in the second positive electrode active material is 10-16-10-9。
4. The positive electrode sheet for a lithium battery as claimed in claim 1, wherein the raw material of the first positive active material layer comprises: the positive electrode comprises a first positive electrode active material layer, a conductive agent and a binder, wherein the second positive electrode active material layer comprises the following raw materials: a second positive electrode active material, a conductive agent, and a binder.
5. The positive electrode sheet for a lithium battery as claimed in claim 1, wherein the functional layer further comprises a first normal coating region remote from the positive electrode tab and connected to the double-layered coating region, the first normal coating region being formed of a single layer of a third positive active material layer, and the sum of the capacity per unit area of the first positive active material layer and the capacity per unit area of the second positive active material layer being not less than the capacity per unit area of the third positive active material layer.
6. The positive electrode sheet for a lithium battery as claimed in claim 5, wherein the thickness of the first positive electrode active material layer in the positive electrode sheet is T203, the thickness of the second positive electrode active material layer is T204, the thickness of the third positive electrode active material layer is T205, 10 μm T203 ≦ 60 μm, 10 μm T204 ≦ 60 μm, -50 μm T203-T204 ≦ 50 μm, -3 μm T203+ T204-T205 ≦ 6 μm.
7. The positive electrode sheet for a lithium battery according to claim 5, wherein both surfaces of the positive electrode current collector are coated with a functional layer, and the functional layer of the first surface opposite to the second surface includes a second normal coating region mirror-symmetrical to the double-layered coating region and the first normal coating region, the second normal coating region being formed of a single layer of a third positive electrode active material layer.
8. A wound cell comprising the positive electrode sheet of the lithium battery of claim 1.
9. The winding type battery cell of claim 8, wherein the length of the first positive electrode active material layer in the positive plate is L103, the length of the second positive electrode active material layer is L104, the winding core width is W, L203 is more than or equal to 0.5W and less than or equal to 3W, and L204 is more than or equal to 0.5W and less than or equal to 3W.
10. A lithium ion battery comprising the wound cell of claim 8.
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| CN111540879A (en) * | 2020-05-08 | 2020-08-14 | 珠海冠宇电池股份有限公司 | Positive plate, preparation method and lithium ion battery comprising positive plate |
| CN111554878A (en) * | 2020-05-08 | 2020-08-18 | 珠海冠宇电池股份有限公司 | Positive plate, preparation method and lithium ion battery comprising positive plate |
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| CN111916844A (en) * | 2020-08-13 | 2020-11-10 | 东莞新能安科技有限公司 | Electrochemical device and electronic device |
| CN111916845A (en) * | 2020-08-13 | 2020-11-10 | 东莞新能安科技有限公司 | Electrochemical device and electronic device |
| CN111969214A (en) * | 2020-08-19 | 2020-11-20 | 珠海冠宇电池股份有限公司 | Positive plate with special-shaped structure and lithium ion battery comprising same |
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| CN111446488A (en) * | 2020-04-30 | 2020-07-24 | 宁德时代新能源科技股份有限公司 | Secondary battery and device thereof |
| CN111540880A (en) * | 2020-05-08 | 2020-08-14 | 珠海冠宇电池股份有限公司 | Negative plate, preparation method and lithium ion battery comprising negative plate |
| CN111540879A (en) * | 2020-05-08 | 2020-08-14 | 珠海冠宇电池股份有限公司 | Positive plate, preparation method and lithium ion battery comprising positive plate |
| CN111554878A (en) * | 2020-05-08 | 2020-08-18 | 珠海冠宇电池股份有限公司 | Positive plate, preparation method and lithium ion battery comprising positive plate |
| CN111785923A (en) * | 2020-07-31 | 2020-10-16 | 蜂巢能源科技有限公司 | Lithium ion battery anode, preparation method and application thereof, and lithium ion battery |
| CN111916844A (en) * | 2020-08-13 | 2020-11-10 | 东莞新能安科技有限公司 | Electrochemical device and electronic device |
| CN111916845A (en) * | 2020-08-13 | 2020-11-10 | 东莞新能安科技有限公司 | Electrochemical device and electronic device |
| CN111969214A (en) * | 2020-08-19 | 2020-11-20 | 珠海冠宇电池股份有限公司 | Positive plate with special-shaped structure and lithium ion battery comprising same |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113594413A (en) * | 2021-08-10 | 2021-11-02 | 星恒电源股份有限公司 | Positive plate for balancing lithium ion diffusion and lithium ion battery |
| CN113594413B (en) * | 2021-08-10 | 2024-04-26 | 星恒电源股份有限公司 | Positive plate for balancing lithium ion diffusion and lithium ion battery |
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| CN112750974B (en) | 2022-08-09 |
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