Negative electrode sheet, battery cell and battery
By forming multiple pits at the corner bent portion of the graphite active material layer of the lithium-ion battery negative electrode sheet, the problem of lithium-ion liquid spots in the corner bent portion of the battery when charging at a large rate is solved, and effective retention of the electrolyte and extended battery life are achieved.
Patent Information
- Application Number
- CN202420130714.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-18
- Publication Date
- 2025-04-01
- Estimated Expiration
- 2034-01-18
AI Technical Summary
When charging mobile phone batteries at high-speed charging, there is a problem of purple spot lithium excretion at the corner bend of the lithium-ion battery negative electrode, which is difficult to effectively solve the problem of existing technology.
A plurality of pits are formed at the corner bent portion of the graphite active material layer of the negative electrode sheet to form the negative electrode sheet, and the electrolyte accumulates in the pit, and the electrolyte is retained after it is transformed to slow down the drying.
By setting pits in the corner bent portion of the negative electrode sheet, the electrolyte can be effectively retained, the electrolyte can be slowed down and the problem of purple spot lithium-ion analysis in the negative electrode sheet can be improved.
Smart Images
Figure CN222705533U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of new energy batteries, and in particular to a negative electrode sheet, a battery core and a battery. Background Art
[0002] When charging the mobile phone battery at a high rate, the negative electrode of the lithium-ion battery will have purple spots and lithium deposition at the corners. This is because the electrolyte at the corners of the negative electrode is squeezed out under the formation pressure. During use, due to the consumption of charge and discharge, the electrolyte is easy to dry up, resulting in the inability to embed lithium, thus forming purple spots, and finally developing into lithium deposition.
[0003] In order to improve the fast charging performance of the battery and increase the liquid retention capacity of the battery, the prior art uses a graphite material with higher charging performance to cover the surface of the negative electrode current collector. However, when this method is used to increase the liquid retention capacity, the electrolyte will still be squeezed out under the formation pressure, and the effect of improving the purple spot lithium precipitation at the corner bend of the negative electrode plate is not obvious.
[0004] In view of this, it is indeed necessary to provide a technical solution to the above problems. Utility Model Content
[0005] The main purpose of the utility model is to provide a negative electrode plate, aiming to effectively solve the problem of purple spots and lithium precipitation at the corner bending part of the negative electrode plate.
[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0007] The utility model provides a negative electrode sheet, comprising:
[0008] A negative electrode current collector, wherein at least one surface of the negative electrode current collector is provided with a graphite active material layer, and a plurality of pits are formed on the surface of at least one graphite active material layer located at a corner bending portion of the negative electrode current collector.
[0009] Preferably, the negative electrode current collector has a graphite active material layer on only one surface, and the pit is formed on the graphite active material layer and is located on the outer arc surface of the corner bending portion.
[0010] Preferably, the graphite active material layer is distributed on the upper and lower surfaces of the negative electrode current collector.
[0011] Preferably, the distribution density of the pits is 1-10 / cm 2 .
[0012] Preferably, the width of the pit distribution area is greater than the width of the corner bend, and the pits are distributed across the width direction of the negative electrode sheet.
[0013] Preferably, the width of the distribution area of the pits is 5mm-20mm.
[0014] Preferably, the bottom of the pit is arc-shaped, the hole diameter is 0.2-5 mm, and the depth is 2-20 μm.
[0015] Preferably, the pit is a conical hole.
[0016] The utility model also provides a battery core, comprising a positive electrode sheet and a negative electrode sheet, wherein the negative electrode sheet is the negative electrode sheet described above.
[0017] The utility model further provides a battery, comprising the battery core as described above.
[0018] Compared with the prior art, the beneficial effects of the utility model are: the negative electrode plate is formed with pits due to the corner bending part of the graphite active material layer. The electrolyte will gather in the pits after liquid injection. After formation, the electrolyte is squeezed out by the formation fixture due to the flat surface of other places in the winding core; due to the presence of pits in the corner bending part, a large amount of electrolyte can be retained. During the subsequent use of the battery or cycle testing, the electrolyte in the pits can supplement the electrolyte consumed due to charging and discharging, slowing down the drying of the electrolyte and improving the problem of purple spots and lithium precipitation in the negative electrode plate. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a schematic diagram of the structure of a negative electrode sheet in one embodiment of the utility model;
[0020] Figure 2 This is a schematic structural diagram of a negative electrode sheet in another embodiment of the utility model;
[0021] Figure 3 This is a schematic structural diagram of a negative electrode sheet in another embodiment of the utility model;
[0022] Figure 4 This is a schematic diagram of the structure of the negative electrode sheet after winding in one embodiment of the utility model;
[0023] Figure 5 This is a schematic diagram of the structure of a negative electrode sheet after winding in another embodiment of the utility model;
[0024] Figure 6 This is a schematic structural diagram of a stamping device for forming pits on the surface of a negative electrode sheet in one embodiment of the utility model;
[0025] Figure 7 This is a schematic structural diagram of a stamping device for forming pits on the surface of a negative electrode sheet in another embodiment of the utility model;
[0026] Figure 8 It is a schematic structural diagram of a stamping device for forming pits on the surface of a negative electrode plate in another embodiment of the utility model.
[0027] 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
[0028] Embodiments of the present invention are described below with reference to the accompanying drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that for the purpose of clarity, the representation and description of components or processes that are not related to the present invention and are known to those of ordinary skill in the art are omitted in the drawings and descriptions.
[0029] The utility model is further described below in conjunction with the accompanying drawings.
[0030] The utility model provides a negative electrode plate, see Figure 1 , Figure 2 and Figure 3 , Figure 1 It is a schematic structural diagram of a negative electrode plate in one embodiment of the utility model. Figure 2 It is a schematic structural diagram of a negative electrode plate in another embodiment of the utility model. Figure 3 This is a schematic diagram of the structure of a negative electrode plate in another embodiment of the utility model. The negative electrode plate of the utility model includes: a negative electrode collector 11, at least one surface of the negative electrode collector 11 is provided with a graphite active material layer 12, and a plurality of pits 14 are formed on the surface of at least one graphite active material layer 12 located at a corner bend 13 of the negative electrode collector 11. In this embodiment, the material of the negative electrode collector 11 can be copper foil, which includes two surfaces arranged opposite to each other, at least one surface of which is provided with a graphite active material layer 12. The corner bend 13 refers to the part that the negative electrode collector 11 will bend when it is wound. The pits 14 can be formed on the surface of the graphite active material layer 12 by a mold, and they can be distributed in a regular array, or of course, in an irregular array. The embodiment of the utility model provides a pit 14 at the corner bend 13 of the graphite active material layer 12 of the negative electrode plate. After the battery cell made of the negative electrode plate is filled with electrolyte, the electrolyte will gather in the pit 14. After formation, the electrolyte in other parts of the battery cell is squeezed out by the formation fixture due to the flat surface. The corner bend 13 can retain a large amount of electrolyte due to the presence of the pit 14. When the battery is used subsequently or cycle tested, the electrolyte in the pit 14 can supplement the electrolyte consumed by charging and discharging, slow down the drying of the electrolyte, and improve the problem of purple spot lithium precipitation in the negative electrode plate.
[0031] The negative electrode sheet provided in the embodiment of the utility model, the graphite active material layer 12 can be distributed on the upper and lower surfaces of the negative electrode current collector 11, or can be distributed on one surface, such as Figure 1 , Figure 2 and Figure 3When the two surfaces are provided with the graphite active material layer 12, the corner bending parts 13 of the graphite active material layer 12 on the two surfaces can be formed with a plurality of pits, see Figure 2 and Figure 4 , Figure 4 This is a schematic diagram of the structure of the negative electrode sheet after winding in another embodiment of the utility model. That is, multiple pits are formed on the inner arc surface B and the outer arc surface A of the corner bending part 13. Since pits are formed on both surfaces, more electrolyte can be retained and the electrolyte can be dried better.
[0032] See also Figure 1 , Figure 3 and Figure 5 In a preferred embodiment of the present invention, a plurality of pits 14 can also be formed at the corner bending portion 13 of the graphite active material layer 12 on one surface. Figure 1 When only one surface of the negative electrode current collector 11 is covered with the graphite active material layer 12, a plurality of pits 14 are formed on the graphite active material layer 12 and located on the outer arc surface A of the corner bending portion 13. Figure 3 and Figure 5 When both the upper and lower surfaces of the negative electrode current collector 11 are covered with the graphite active material layer 12, a plurality of pits may be formed at the corner bend 13 of a graphite active material layer 12, but the plurality of pits 14 should be formed at the corner bend 13 corresponding to the outer arc surface A. Compared with the corner bend 13 corresponding to the inner arc surface B, the corner bend 13 corresponding to the outer arc surface A has a plurality of pits 14 formed therein, which can store more electrolyte and has a better effect.
[0033] In the embodiment of the utility model, the pits 14 are evenly distributed on the corresponding corner bending parts 13, and the distribution density of the pits 14 can be 1-10 / cm 2 Preferably, the distribution density of the pits 14 is 4-6 / cm 2 In this embodiment, the distribution density of the pits 14 can be determined according to the area and size of the negative electrode current collector. When the area of the negative electrode current collector 11 is large, the distribution density of the pits 14 can be selected to be relatively large. When the area of the negative electrode current collector 11 is small, the distribution density of the pits 14 can be selected to be relatively small.
[0034] The width of the distribution area of the pits 14 can be greater than the width of the corner bend 13, and the pits 14 are distributed in the width direction of the negative electrode sheet. Since the negative electrode sheet will be bent in multiple layers, the corner bends 13 of each layer are of different sizes. In order to retain more electrolyte, it can be selected to set the corner bends 13 of each layer to be covered by the pits 14, that is, the width of the pits 14 distributed on each layer of the graphite active material layer 12 is greater than the width of the corner bend 13.
[0035] In the embodiment of the utility model, the width of the distribution area of the pits 14 can be selected according to the width of the negative electrode plate, preferably 5mm-20mm. In a preferred embodiment, the width of the distribution area of the pits 14 is 10mm-15mm.
[0036] It can be understood that in the above-mentioned embodiment, there are many choices for the shape and size of the pit 14, and the bottom can be selected to be an arc shape, the hole diameter can be 0.2-5mm, and the depth can be 2-20μm. In a preferred embodiment, the hole diameter can be selected to be 2-4mm, and the preferred depth is 10-15μm. The depth of the pit 14 should not be too deep, and is generally controlled within the range of 2-20μm. If the imprint is too deep, the graphite active material layer 12 is easily damaged.
[0037] In another preferred embodiment, the pit 14 can be selected as a conical hole, the bottom of the conical hole is arc-shaped, the hole diameter is 0.2-5mm, and the depth is 2-20μm. The preferred hole diameter is 2-4mm, and the preferred depth is 10-15μm. Since the conical hole is used and the bottom of the conical hole is set to be arc-shaped, the graphite structure of the graphite active material layer will not be destroyed, and the amount of graphite in the graphite active material layer will not be lost, thereby ensuring the negative electrode capacity of the battery.
[0038] The utility model also provides a battery cell, which includes a positive electrode sheet and a negative electrode sheet, and the negative electrode sheet is the above negative electrode sheet. In addition to the positive electrode sheet and the negative electrode sheet, it also includes an electrolyte filled therein. Since the above negative electrode sheet is included, the battery cell of the utility model can retain more electrolyte due to the presence of a pit at the corner bend of the negative electrode sheet. Even if the electrolyte at the plane is squeezed out during the formation process, the corner bend can still retain a large amount of electrolyte. During the subsequent use of the battery or cycle testing, the electrolyte in the depression can supplement the electrolyte consumed due to charging and discharging, slowing down the drying of the electrolyte and improving the problem of purple spot lithium precipitation.
[0039] The utility model also provides a battery, which includes the above battery core. Due to the above battery core, the battery of the utility model can replenish the electrolyte consumed by charging and discharging, effectively improve the purple spot lithium precipitation phenomenon, and extend the battery life.
[0040] The beneficial effects of the utility model are as follows: the negative electrode plate is embossed with a pit 14 on the corner bend 13 of the graphite active material layer 12, and the electrolyte will gather in the pit 14 after injection. After formation, the electrolyte is squeezed out by the formation fixture due to the flat surface of other places in the winding core; the corner bend 13 can retain a large amount of electrolyte due to the presence of the pit 14. When the battery is subsequently used or cycle tested, the electrolyte in the pit 14 can supplement the electrolyte consumed due to charging and discharging, slowing down the drying of the electrolyte and improving the problem of purple spot lithium precipitation on the negative electrode plate.
[0041] The negative electrode sheet provided by the utility model has a concave pit 14 at the corner bending portion 13 of the graphite active material layer 12 which is formed by stamping with a dedicated stamping device. The utility model also provides a concave pit stamping device, see Figure 6 , Figure 7 , Figure 8 , Figure 6 This is a schematic structural diagram of a stamping device for forming pits on the surface of a negative electrode sheet in one embodiment of the utility model; Figure 7 This is a schematic structural diagram of a stamping device for forming pits on the surface of a negative electrode sheet in another embodiment of the utility model; Figure 8 Schematic diagram of the structure of a stamping device for forming a pit on the surface of a negative electrode sheet in another embodiment of the utility model. In one embodiment of the utility model, the pit stamping device comprises: a stamping plate body 20, a surface of which is provided with a plurality of cones 21, and the plurality of cones 21 are evenly distributed with a distribution density of 1-10 / cm 2 The tip of the cone 21 is rounded, the bottom diameter of the cone 21 is 0.2-5mm, the tip diameter of the cone 21 is 0.05-0.5m, and the height of the cone 21 is 2-20μm. Since the tip of the cone on the adopted pit stamping device is rounded, when stamping the pit on the corner bending part of the negative electrode plate, the bottom of the pit is arc-shaped, which will not destroy the graphite structure of the graphite active material layer and will not lose the amount of graphite in the graphite active material layer, thereby ensuring the negative electrode capacity of the battery.
[0042] In the pit stamping device provided by the present invention, the stamping plate body 20 is a cylinder or a cuboid. Figure 6 If the platen body 20 is a rectangular parallelepiped, the plurality of cones 21 are disposed on a surface formed by the length and width of the rectangular parallelepiped. Figure 8 If the stamping plate body 20 is a cylinder, multiple cones 21 are arranged on the side of the cylinder. The width of the distribution area of the cones 21 is slightly larger than the width of the corner bending portion 13, generally set to 5mm-20mm; the length of the distribution area of the cones 21 is slightly larger than the width of the corresponding negative electrode sheet.
[0043] The concave embossing device provided by the utility model needs to be made of hard insulating materials, such as hard plastic, hard resin and other polymer insulating materials. The negative electrode plate is embossed by the concave embossing device provided by the utility model after the rolling process is completed. The specific embossing process is as follows: the negative electrode plate to be embossed is placed on a force-bearing base, and then one side of the concave embossing device provided with multiple cones 21 is placed on the corner bend corresponding to the graphite active material layer to be embossed, so that the cone distribution area covers the corresponding corner bend, and then a pressure of 0.1-0.5mPa is applied to the embossing plate body 20, so that the cone 21 is embossed and recessed into the surface of the graphite active material layer by 2-20μm, and then the concave embossing device is taken out to complete the embossing of the corner bend 13 of the corresponding negative electrode plate. Among them, the force-bearing base is a soft base, which can be made of soft materials such as silicone, acrylic, soft resin, nylon, etc.
[0044] In the negative electrode sheet provided by the utility model, during the stamping process of the corner bending portion 13, the depth of the pit 14 needs to be controlled within the range of 2-20 μm. If the stamping is too deep, the graphite active material layer 12 is easily damaged.
[0045] The negative electrode sheet provided by the utility model can be stamped on the corner bends 13 corresponding to the upper and lower graphite active material layers 12, or on the corner bends 13 corresponding to one of the graphite active material layers 12. If stamping is performed on one of the layers, when the negative electrode sheet is subsequently wound, the stamped corner bends 13 should correspond to the outer arc surface A. Compared with the corner bends 13 corresponding to the inner arc surface B, the corner bends 13 corresponding to the outer arc surface A can store more electrolyte.
[0046] The negative electrode printing technology of the utility model can create a depression for containing electrolyte at the corner bend of graphite without destroying the graphite structure or losing the amount of graphite, and the cost is significantly lower than other technologies, which can effectively improve the problem of purple spot lithium precipitation at the corner bend.
[0047] Those skilled in the art may combine and associate different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.
[0048] The above are only partial or preferred embodiments 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 negative electrode plate, characterized in that: include: A negative electrode current collector, wherein at least one surface of the negative electrode current collector is provided with a graphite active material layer, and a plurality of pits are formed on the surface of at least one graphite active material layer located at a corner bending portion of the negative electrode current collector.
2. The negative electrode sheet according to claim 1, characterized in that: The negative electrode current collector has a graphite active material layer on only one surface, and the pit is formed on the graphite active material layer and is located on the outer arc surface of the corner bending portion.
3. The negative electrode sheet according to claim 1, characterized in that: The graphite active material layer is distributed on the upper and lower surfaces of the negative electrode current collector.
4. The negative electrode sheet according to any one of claims 1 to 3, characterized in that: The distribution density of the pits is 1-10 / cm 2 .
5. The negative electrode sheet according to claim 4, characterized in that: The width of the pit distribution area is greater than the width of the corner bending portion, and the pits are distributed across the width direction of the negative electrode sheet.
6. The negative electrode sheet according to claim 5, characterized in that: The width of the distribution area of the pits is 5mm-20mm.
7. The negative electrode sheet according to claim 4, characterized in that: The bottom of the pit is in an arc shape, the hole diameter is 0.2-5 mm, and the depth is 2-20 μm.
8. The negative electrode sheet according to claim 7, characterized in that: The pit is a conical hole.
9. A battery cell, comprising a positive electrode sheet and a negative electrode sheet, characterized in that: The negative electrode plate is the negative electrode plate according to any one of claims 1 to 8.
10. A battery, characterized in that: Comprising the battery cell as claimed in claim 9.