Electrode, cell and battery
By designing the current collector, active material layer and separator structure in the lithium battery electrode sheet, the problem of battery cell deformation caused by volume expansion during charging and discharging of the anode electrode sheet is solved, and the normal use of the battery is achieved.
Patent Information
- Application Number
- CN202420886080.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-25
- Publication Date
- 2025-04-04
- Estimated Expiration
- 2034-04-25
AI Technical Summary
The anode plate of the lithium battery cell is prone to volume expansion during charging and discharging, causing the battery cell to become thicker and deform, affecting the normal use of the battery.
An electrode sheet is designed, including a current collector, a first active material layer, a second active material layer, a first separator and a second separator. By providing a first diaphragm on the side where the first active material layer is away from the current collector, the volume expansion is buffered; by providing a second diaphragm on the side where the second active material layer is away from the current collector, the electrode sheet is prevented from deforming due to volume expansion.
Effectively buffer and control the volume expansion of the electrode plate to prevent the battery from becoming thicker and deforming, and ensure the normal use of the battery during charging and discharging.
Smart Images
Figure CN222720439U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of lithium batteries, in particular to a pole piece, a battery core and a battery. Background Art
[0002] Lithium battery refers to a battery containing lithium (including metallic lithium, lithium alloys, lithium ions, and lithium polymers) in the electrochemical system. In recent years, lithium batteries have been widely used in digital products and other fields due to their many advantages such as long cycle life, good safety performance, and rapid charging and discharging.
[0003] Lithium batteries are usually manufactured by assembling positive electrode sheets, negative electrode sheets and separators into battery cells using winding or lamination equipment, and then encapsulating the battery cells in a casing.
[0004] At present, with the continuous development of battery technology, the demand for lithium battery ED (energy density) is increasing year by year, which in turn puts higher requirements on electrode materials and processes. Therefore, silicon-carbon materials have gradually been introduced into anode electrodes. However, due to the large volume expansion of silicon-carbon materials themselves, the battery cells are prone to thickening and deformation during the charging and discharging process, affecting the normal use of the battery. Utility Model Content
[0005] The main purpose of the utility model is to provide a pole piece, aiming to solve the technical problem that the anode pole piece of the current lithium battery cell is prone to volume expansion, resulting in the cell becoming thicker and deformed.
[0006] In order to achieve the above-mentioned purpose, the utility model provides a pole piece, which comprises:
[0007] A current collector, the current collector comprising an inner side surface facing the winding central axis and an outer side surface facing away from the winding central axis after the pole piece is wound;
[0008] A first active material layer is disposed on the inner side of the current collector;
[0009] A second active material layer is disposed on the outer side of the current collector;
[0010] A first diaphragm is provided on a side of the first active material layer away from the current collector, and the first diaphragm is used to buffer the volume expansion of the first active material layer;
[0011] The second diaphragm is arranged on a side of the second active material layer away from the current collector, and the second diaphragm is used to prevent the pole piece from being deformed due to the volume expansion of the first active material layer.
[0012] In some embodiments, the first separator comprises a porous membrane, and the porous membrane is attached to the first active material layer; and / or,
[0013] The second separator includes a high-viscosity oily film, and the high-viscosity oily film is bonded to the second active material layer.
[0014] In some embodiments, the first active material layer has first straight regions and first corner regions alternately arranged along a winding direction;
[0015] The first corner region is provided with a first concave hole, and the first concave hole is formed on a side of the first active material layer facing away from the current collector.
[0016] In some embodiments, the first concave hole is a linear hole, and the first concave hole is provided with one, and the first concave hole is extended along the height direction of the current collector; or
[0017] The first concave holes are dot-shaped holes, a plurality of the first concave holes are provided, and the plurality of the first concave holes are spaced apart along the height direction of the current collector.
[0018] In some embodiments, the second active material layer has second straight regions and second corner regions alternately arranged along the winding direction;
[0019] The second corner region is provided with a second concave hole, and the second concave hole is formed on a side of the second active material layer facing away from the current collector.
[0020] In some embodiments, the first active material layer is a mixed layer made of graphite and silicon carbon, and the second active material layer is a graphite layer made of graphite.
[0021] The utility model also proposes a pole piece, which includes an inner ring layer made of a mixture of graphite and silicon carbon and an outer ring layer made of graphite, wherein the inner ring layer is located on the side of the pole piece facing the winding center axis of the battery cell when the pole piece is wound to form a battery cell, and the outer ring layer is located on the side of the pole piece facing away from the winding center axis of the battery cell when the pole piece is wound to form a battery cell.
[0022] In some embodiments, the inner ring layer has a third straight area and a third corner area alternately arranged along the winding direction, and the third corner area is provided with a third concave hole; and / or,
[0023] The outer ring layer has fourth straight areas and fourth corner areas alternately arranged along the winding direction, and the fourth corner area is provided with a fourth concave hole.
[0024] The utility model also provides a battery core, which includes a winding core, wherein the winding core is formed by winding an anode pole piece and a cathode pole piece stacked in sequence, and the anode pole piece adopts the pole piece as described above.
[0025] The utility model also provides a battery, which comprises a shell and a battery core arranged in the shell, and the battery core is the battery core as described above.
[0026] In the pole piece of the technical solution of the utility model, the current collector includes an inner side surface facing the central axis of the winding of the pole piece and an outer side surface facing away from the central axis of the winding of the pole piece after the pole piece is wound, and the first active material layer and the second active material layer are respectively arranged on the inner side surface and the outer side surface of the current collector, and a first diaphragm is arranged on the side of the first active material layer away from the current collector so as to buffer the volume expansion of the first active material layer by the first diaphragm, and a second diaphragm is arranged on the side of the second active material layer away from the current collector so as to prevent the pole piece from being deformed due to the volume expansion of the first active material layer by the second diaphragm, thereby improving the phenomenon that the battery cell is prone to thickening and deformation during the charging and discharging process, so as to ensure the normal use of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is a schematic diagram of the structure of a pole piece in one embodiment of the utility model;
[0028] Figure 2 This is a schematic diagram of the structure of a pole piece in another embodiment of the utility model;
[0029] Figure 3 This is a structural schematic diagram of a portion of a pole piece in another embodiment of the utility model;
[0030] Description of Figure Numbers:
[0031] Label name Label name 100 current collector 212 First Corner Area 210 First active material layer 10 The first recessed hole 220 Second active material layer 221 The second straight area 310 First diaphragm 222 Second Corner Area 320 Second diaphragm 20 The second recessed hole 211 First straight area
[0032] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0033] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0034] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0035] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.
[0036] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.
[0037] The utility model embodiment provides a pole piece, referring to Figure 1 and Figure 2 The pole piece includes: a current collector 100, a first active material layer 210, a second active material layer 220, a first diaphragm 310 and a second diaphragm 320. The current collector 100 includes an inner side surface facing the winding center axis and an outer side surface facing away from the winding center axis after the pole piece is wound; the first active material layer 210 is arranged on the inner side surface of the current collector 100; the second active material layer 220 is arranged on the outer side surface of the current collector 100; the first diaphragm 310 is arranged on the side of the first active material layer 210 away from the current collector 100, and the first diaphragm 310 is used to buffer the volume expansion of the first active material layer 210; the second diaphragm 320 is arranged on the side of the second active material layer 220 away from the current collector 100, and the second diaphragm 320 is used to prevent the pole piece from deforming.
[0038] The pole piece involved in this embodiment can be an anode pole piece, which is applied to a wound battery cell, and can be stacked with the cathode pole piece of the wound battery cell and then wound with each other to form a wound battery cell. When the pole piece is an anode pole piece, the current collector 100 can be made of copper foil, and the first active material layer 210 and the second active material layer 220 can be made of anode active slurry. The specific anode active slurry used can be set according to actual conditions. For example, the anode active slurry used in the first active material layer 210 can be a mixed slurry formed by mixing graphite and silicon carbon, and the anode active slurry used in the second active material layer 220 can be pure graphite slurry, including but not limited to this. Optionally, the surface density of the second active material layer 220 is greater than the surface density of the first active material layer 210, and the difference between the surface density of the second active material layer 220 and the surface density of the first active material layer 210 is approximately 10g / 1540mm 2 ~15g / 1540mm2 Optionally, the compaction density of the second active material layer 220 is greater than the compaction density of the first active material layer 210, and the difference between the compaction density of the second active material layer 220 and the compaction density of the first active material layer 210 is approximately 0.05 g / cm 3 ~0.1g / cm 3 .
[0039] Among them, on the side of the first active material layer 210 away from the current collector 100, the first diaphragm 310 is combined with the first active material layer 210, and the main function of the first diaphragm 310 is to buffer the volume expansion of the first active material layer 210. Specifically, the first active material layer 210 uses silicon-carbon material, which is prone to volume expansion during use. When the volume of the first active material layer 210 expands, the first diaphragm 310 can buffer it, avoid excessive volume expansion of the first active material layer 210, and reduce the volume expansion effect of the first active material layer 210. The type of diaphragm used by the first diaphragm 310 can be set according to actual conditions, and can be selected as long as it can play the above-mentioned role, and this embodiment does not limit this.
[0040] On the side of the second active material layer 220 facing away from the current collector 100, the second diaphragm 320 is arranged in combination with the second active material layer 220. The main function of the second diaphragm 320 is to prevent the pole piece from being deformed due to the volume expansion of the first active material layer 210. Specifically, the first active material layer 210 uses silicon-carbon material, which is prone to volume expansion during use, thereby causing the pole piece to be deformed as a whole. When the volume of the first active material layer 210 expands, the second diaphragm 320 can form a supporting effect in the pole piece through its own close arrangement with the second active material layer 220, thereby preventing the pole piece from being deformed due to the volume expansion of the first active material layer 210. The type of diaphragm used by the second diaphragm 320 can be set according to actual conditions, and any type of diaphragm that can play the aforementioned role can be selected, and this embodiment does not limit this.
[0041] That is, the pole piece of the utility model is provided with a first diaphragm 310 on a side of the first active material layer 210 away from the current collector 100, so that the first diaphragm 310 buffers the volume expansion of the first active material layer 210, and a second diaphragm 320 is provided on a side of the second active material layer 220 away from the current collector 100, so that the second diaphragm 320 prevents the pole piece from being deformed due to the volume expansion of the first active material layer 210, thereby improving the phenomenon that the battery cell is prone to thickening and deformation during the charge and discharge process, so as to ensure the normal use of the battery.
[0042] In some embodiments, reference Figure 1 and Figure 2, the first separator 310 includes a porous film, and the porous film is attached to the first active material layer 210; and / or,
[0043] The second separator 320 includes a high-viscosity oily film, and the high-viscosity oily film is bonded to the second active material layer 220 .
[0044] The porous film used in the first separator 310 has uniform thickness and excellent mechanical properties (including tensile strength and puncture resistance), air permeability, and physical and chemical properties, and can buffer the volume expansion of the first active material layer 210. Micropores are formed on the porous film, and the micropores allow the electrolyte to pass through, thereby ensuring the flow of the electrolyte.
[0045] The high-viscosity oily film used in the second diaphragm 320 is bonded to the second active material layer 220 , and is tightly and firmly bonded to the second active material layer 220 , forming a stable support in the electrode to prevent the electrode from being deformed due to the volume expansion of the first active material layer 210 .
[0046] In some embodiments, reference Figure 3 , the first active material layer 210 has first straight regions 211 and first corner regions 212 alternately arranged along the winding direction;
[0047] The first corner region 212 is provided with a first concave hole 10 , and the first concave hole 10 is formed concavely on a side of the first active material layer 210 facing away from the current collector 100 .
[0048] Specifically, after the pole piece is wound, the first active material layer 210 is formed with a plurality of first straight areas 211 and a plurality of first corner areas 212. Taking the winding direction of the pole piece as a reference direction, the plurality of first straight areas 211 and the plurality of first corner areas 212 are alternately arranged one by one, that is, there is a first corner area 212 between any two adjacent first straight areas 211, and there is a first straight area 211 between any two adjacent first corner areas 212.
[0049] Among them, the first concave hole 10 set at the first corner area 212 can be one or more, which are set according to actual conditions. The first active material layer 210 can accommodate electrolyte to increase liquid retention through the first concave hole 10 set at the corner position, avoid the occurrence of lithium precipitation at the corner, and improve the abnormal thickness phenomenon of the battery cell in the later stage of the cycle. Optionally, the first concave hole 10 can be formed by laser drilling.
[0050] The first concave hole 10 can be arranged in various forms. In some embodiments, optionally, the first concave hole 10 is a linear hole, and one first concave hole 10 is provided, and one first concave hole 10 is extended along the height direction of the current collector 100; or, the first concave hole 10 is a point hole, and multiple first concave holes 10 are provided, and multiple first concave holes 10 are arranged at intervals along the height direction of the current collector 100.
[0051] In some embodiments, reference Figure 3 , the second active material layer 220 has second straight regions 221 and second corner regions 222 alternately arranged along the winding direction;
[0052] The second corner region 222 is provided with a second concave hole 20 , and the second concave hole 20 is formed concavely on a side of the second active material layer 220 facing away from the current collector 100 .
[0053] Specifically, after the pole piece is wound, the second active material layer 220 is formed with a plurality of second straight areas 221 and a plurality of second corner areas 222. Taking the winding direction of the pole piece as a reference direction, the plurality of second straight areas 221 and the plurality of second corner areas 222 are alternately arranged one by one, that is, there is a second corner area 222 between any two adjacent second straight areas 221, and there is a second straight area 221 between any two adjacent second corner areas 222.
[0054] Among them, the second concave hole 20 set at the second corner area 222 can be one or more, which are set according to actual conditions. The second active material layer 220 can accommodate electrolyte to increase liquid retention through the second concave hole 20 set at the corner position, avoid the occurrence of lithium precipitation at the corner, and improve the abnormal thickness phenomenon of the battery cell in the later stage of the cycle. Optionally, the second concave hole 20 can be formed by laser drilling.
[0055] The second recessed hole 20 may be arranged in various forms. In some embodiments, optionally, the second recessed hole 20 is a dot-shaped hole, and one second recessed hole 20 is provided, and one second recessed hole 20 is extended along the height direction of the current collector 100; or, the second recessed hole 20 is a dot-shaped hole, and multiple second recessed holes 20 are provided, and multiple second recessed holes 20 are arranged at intervals along the height direction of the current collector 100.
[0056] In some embodiments, the first active material layer 210 is a mixed layer made of graphite and silicon-carbon, and the second active material layer 220 is a graphite layer made of graphite. Specifically, in actual production, the first active material layer 210 is made by mixing a graphite material with a silicon-carbon material, and then applying the mixed material to the inner side of the current collector 100, and the second active material layer 220 is made by applying a graphite material to the outer side of the current collector 100. Among them, the volume expansion of the graphite layer used in the second active material layer 220 to the mixed layer of graphite and silicon-carbon used in the first active material layer 210 increases pressure and restraint force, so as to restrain the expansion of silicon-carbon in the first active material layer 210, thereby reducing the expansion of the first active material layer 210.
[0057] The utility model embodiment also proposes a pole piece, which includes an inner ring layer made of a mixture of graphite and silicon carbon and an outer ring layer made of graphite, wherein the inner ring layer is located on the side of the pole piece facing the winding center axis of the battery cell when the pole piece is wound to form a battery cell, and the outer ring layer is located on the side of the pole piece facing away from the winding center axis of the battery cell when the pole piece is wound to form a battery cell. Among them, the graphite in the outer ring layer increases the pressure and restraint force to the volume expansion of silicon carbon in the inner ring layer, so as to restrain the expansion of silicon carbon in the inner ring layer and reduce the volume expansion effect of the inner ring layer. Among them, the inner ring layer can be the first active material layer 210 mentioned in the above embodiment, and the outer ring layer can be the second active material layer 220 mentioned in the above embodiment.
[0058] In some embodiments, the inner ring layer has a third straight area and a third corner area alternately arranged along the winding direction, and the third corner area is provided with a third concave hole; and / or,
[0059] The outer ring layer has fourth straight areas and fourth corner areas which are alternately arranged along the winding direction, and the fourth corner area is provided with a fourth concave hole.
[0060] Specifically, after the pole piece is wound, the inner ring layer is formed with a plurality of third straight areas and a plurality of third corner areas. Taking the winding direction of the pole piece as the reference direction, the plurality of third straight areas and the plurality of third corner areas are arranged alternately one by one, that is, there is a third corner area between any two adjacent third straight areas, and there is a third straight area between any two adjacent third corner areas. The third concave hole arranged at the third corner area may be one or more, and is arranged according to actual conditions. The inner ring layer can accommodate electrolyte to increase liquid retention through the third concave hole arranged at the corner position, avoid the occurrence of lithium precipitation at the corner, and improve the abnormal thickness phenomenon of the battery cell in the later stage of the cycle. Optionally, the third concave hole can be formed by laser drilling.
[0061] Specifically, after the pole piece is wound, the outer ring layer is formed with a plurality of fourth straight areas and a plurality of fourth corner areas. Taking the winding direction of the pole piece as the reference direction, the plurality of fourth straight areas and the plurality of fourth corner areas are arranged alternately one by one, that is, there is a fourth corner area between any two adjacent fourth straight areas, and there is a fourth straight area between any two adjacent fourth corner areas. Among them, the fourth concave hole arranged at the fourth corner area can be one or more, which are arranged according to actual conditions. The outer ring layer can accommodate electrolyte to increase liquid retention through the fourth concave hole arranged at the corner position, avoid the occurrence of lithium precipitation at the corner, and improve the abnormal thickness phenomenon of the battery cell in the later stage of the cycle. Optionally, the fourth concave hole can be formed by laser drilling.
[0062] The utility model also provides a battery cell, which includes a winding core, which is formed by winding an anode pole piece and a cathode pole piece stacked in sequence, and the anode pole piece adopts the pole piece described in the above embodiment. The specific structure of the pole piece refers to the above embodiment. Since the battery cell adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, which will not be repeated here.
[0063] The utility model also provides a battery, which includes a housing and a battery cell disposed in the housing, and the battery cell is the battery cell described in the above embodiment. The specific structure of the battery cell refers to the above embodiment. Since the battery adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the battery can be a cylindrical battery.
[0064] The above description is only a partial or preferred embodiment of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.
Claims
1. A pole piece, characterized in that: include: A current collector, the current collector comprising an inner side surface facing the winding central axis and an outer side surface facing away from the winding central axis after the pole piece is wound; A first active material layer is disposed on the inner side of the current collector; A second active material layer is disposed on the outer side of the current collector; A first diaphragm is provided on a side of the first active material layer away from the current collector, and the first diaphragm is used to buffer the volume expansion of the first active material layer; The second diaphragm is arranged on a side of the second active material layer away from the current collector, and the second diaphragm is used to prevent the pole piece from being deformed due to the volume expansion of the first active material layer.
2. The pole piece according to claim 1, characterized in that: The first separator includes a porous membrane, and the porous membrane is attached to the first active material layer; and / or, The second separator includes a high-viscosity oily film, and the high-viscosity oily film is bonded to the second active material layer.
3. The pole piece according to claim 1, characterized in that: The first active material layer has first straight regions and first corner regions alternately arranged along a winding direction; The first corner region is provided with a first concave hole, and the first concave hole is formed on a side of the first active material layer facing away from the current collector.
4. The pole piece according to claim 3, characterized in that: The first concave hole is a linear hole, and one of the first concave holes is provided, and one of the first concave holes is extended along the height direction of the current collector; or The first concave holes are dot-shaped holes, a plurality of the first concave holes are provided, and the plurality of the first concave holes are spaced apart along the height direction of the current collector.
5. The pole piece according to claim 1, characterized in that: The second active material layer has second straight regions and second corner regions alternately arranged along a winding direction; The second corner region is provided with a second concave hole, and the second concave hole is formed on a side of the second active material layer facing away from the current collector.
6. The pole piece according to any one of claims 1 to 5, characterized in that: The first active material layer is a mixed layer made of graphite and silicon carbon, and the second active material layer is a graphite layer made of graphite.
7. A pole piece, characterized in that: It includes an inner ring layer made of a mixture of graphite and silicon carbon and an outer ring layer made of graphite. When the pole piece is wound to form a battery cell, the inner ring layer is located on the side of the pole piece facing the winding center axis of the battery cell, and when the pole piece is wound to form a battery cell, the outer ring layer is located on the side of the pole piece facing away from the winding center axis of the battery cell.
8. The pole piece according to claim 7, characterized in that: The inner ring layer has a third straight area and a third corner area alternately arranged along the winding direction, and the third corner area is provided with a third concave hole; and / or, The outer ring layer has fourth straight areas and fourth corner areas alternately arranged along the winding direction, and the fourth corner area is provided with a fourth concave hole.
9. A battery cell, characterized in that: The invention comprises a winding core, wherein the winding core is formed by winding an anode electrode sheet and a cathode electrode sheet which are stacked in sequence, and the anode electrode sheet is the electrode sheet as claimed in any one of claims 1 to 8.
10. A battery, characterized in that: The invention comprises a shell and a battery cell arranged in the shell, wherein the battery cell is the battery cell as claimed in claim 9.