Roll core structure and double-insulation pole cell

Abstract

The utility model provides a roll core structure and a double-insulation pole cell, and belongs to the technical field of new energy batteries. The roll core structure comprises a positive pole piece, a negative pole piece, a diaphragm and an outer ring pole piece, the positive pole piece, the diaphragm and the negative pole piece are sequentially stacked and wound to form a roll core body, the outer ring pole piece is arranged on the outer ring of the roll core body in a surrounding mode, and the inner side face of the outer ring pole piece is coated with positive pole slurry. By adopting the roll core structure and the double-insulation pole column battery core, the problems of insufficient cruising ability and potential safety hazards caused by arrangement defects of the internal roll core in the prior art can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy batteries, in particular to a core structure and a double-insulated pole-column battery cell. Background Art

[0002] As one of the current mainstream energy storage devices, lithium-ion batteries are widely used in new energy vehicles, various portable electronic devices and communication equipment. As a single battery cell that makes up a lithium-ion battery, it usually includes an external aluminum shell and a core structure arranged inside the shell. The pole ear is led out from the core, and the pole ear is conductively connected to the pole column on the shell by an overcurrent sheet.

[0003] In the related art, when the existing core structure is wound, the negative electrode usually covers the positive electrode, and the outermost layer after winding is the negative electrode sheet. Metal particles or electrode shedding powders generated in each process during the production process of the battery cell often remain inside the battery. After the electrolyte is injected into the shell, the metal particles or electrode powders flow to the sides and bottom inside the shell along with the electrode liquid. After the single battery cell is charged, these metal particles and electrode powders will form an electronic channel to connect the negative electrode on the outermost layer of the core and the aluminum shell, causing the potential of the aluminum shell to drop to the lithium-insertion potential of aluminum metal, resulting in electrochemical corrosion of the aluminum shell, increasing the risk of internal short circuit of the battery, and also causing leakage of the electrolyte. To avoid electrochemical corrosion of the aluminum shell, the existing design usually uses a non-insulating plastic on the positive electrode post to make the aluminum shell positively charged to ensure that the potential of the aluminum shell will not drop to the lithium-insertion potential, thus avoiding electrochemical corrosion of the aluminum shell. However, when the aluminum shell is positively charged, it will cause slow discharge of the battery cell, resulting in a decrease in the capacity of the battery cell and insufficient endurance, and also causing potential safety hazards in a specific environment. Summary of the Utility Model

[0004] The embodiment of the utility model provides a core structure and a double-insulated pole-column battery cell, which can solve the problems of insufficient endurance and potential safety hazards caused by defects in the internal core setting in the related art. The technical solution is as follows:

[0005] In the first aspect, the embodiment of the utility model provides a core structure, including:

[0006] a positive electrode sheet, a negative electrode sheet, a separator and an outer-ring electrode sheet,

[0007] the positive electrode sheet, the separator and the negative electrode sheet are sequentially stacked and wound to form a core body, the outer-ring electrode sheet is arranged around the core body, and the inner side surface of the outer-ring electrode sheet is coated with a positive electrode paste.

[0008] Optionally, a plurality of coating areas are evenly arranged on the outer-ring electrode sheet at intervals along the winding direction, and the positive electrode paste is coated on the coating areas.

[0009] Optionally, the outer ring electrode tab is in the shape of a cuboid, the coating area is strip-shaped and arranged along the width direction of the outer ring electrode tab, and the plurality of coating areas are arranged in parallel at intervals along the length direction of the outer ring electrode tab.

[0010] Optionally, the spacing range of the coating areas is from 3 mm to 5 cm.

[0011] Optionally, the outer side surface of the outer ring electrode tab is also surrounded by the separator.

[0012] Optionally, in the winding direction, the positive electrode tab, the negative electrode tab, and the separator are provided with multiple segments.

[0013] In a second aspect, an embodiment of the present invention further provides a double-insulated pole column battery cell, including the core structure described in the first aspect above, further including a cover plate and a lower housing. The core structure is disposed in the lower housing, the cover plate is covered on the lower housing, a pole column is provided on the cover plate, the pole column is connected to the ear end of the core body of the core, and an insulating plastic part is provided between the pole column and the cover plate.

[0014] Optionally, the insulating plastic part is in a cylindrical shape and sleeved on the outside of the pole column, and the cover plate is provided with a mounting hole matching the outer contour of the insulating plastic part.

[0015] The beneficial effects brought by the technical solution provided by the embodiment of the present invention at least include:

[0016] By additionally surrounding an outer layer of an outer ring electrode tab around the core body of the core formed by winding a positive electrode tab, a negative electrode tab, and a separator in conventional production, and the outer ring electrode tab adopts a single-sided coating process, and only on the inner side surface, that is, on the side surface surrounding and facing the core body of the core, the same positive electrode paste as that on the positive electrode tab is coated, so as to realize that the outermost layer of the final core is the positive electrode tab. For the core structure made by this process, when it is put into the shell to complete the over-current connection to form a single battery cell and works. The outer wrapping of the positive electrode tab of the core body of the core ensures that after the aluminum shell and the core body of the core form an electronic path through metal particles and dropped electrode tab metal powder, it is the positive electrode that is connected to the aluminum shell instead of the negative electrode, and the positive electrode tab is connected to the aluminum shell, avoiding the electrochemical corrosion caused by the connection of the aluminum shell to the negative electrode tab, resulting in the potential dropping below the lithium intercalation potential. Thus, the problems of insufficient battery life and safety hazards caused by defects in the internal core setting in the related art are solved. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 is a schematic structural diagram of the core structure provided by the embodiment of the present invention;

[0019] Figure 2 is a schematic structural diagram of the outer pole piece provided by the embodiment of the present invention;

[0020] Figure 3 is a schematic structural diagram of the outer pole piece after winding provided by the embodiment of the present invention;

[0021] Figure 4 is a structural sectional view of the cover plate and the lower housing provided by the present invention;

[0022] Figure 5 is a partial structural sectional view of the cover plate provided by the present invention.

[0023] In the figure: 1 - positive electrode sheet; 2 - negative electrode sheet; 3 - separator; 4 - outer pole piece; 5 - cover plate; 6 - lower housing; 41 - coating area; 51 - pole column; 52 - insulating plastic part; 53 - mounting hole; a - core body of the core. Specific embodiments

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail in conjunction with the drawings.

[0025] Figure 1 is a schematic structural diagram of the core structure provided by the embodiment of the present invention; Figure 2 is a schematic structural diagram of the outer pole piece provided by the embodiment of the present invention; Figure 3 is a schematic structural diagram of the outer pole piece after winding provided by the embodiment of the present invention; Figure 4 is a structural sectional view of the cover plate and the lower housing provided by the present invention; Figure 5 is a partial structural sectional view of the cover plate provided by the present invention. As Figures 1 to 5 shown, the embodiment of the present invention provides a core structure, including a positive electrode sheet 1, a negative electrode sheet 2, a separator 3, and an outer pole piece 4.

[0026] Among them, the positive electrode sheet 1, the separator 3, and the negative electrode sheet 2 are sequentially stacked and wound to form a core body a of the core, the outer pole piece 4 is disposed around the outer circle of the core body a of the core, and the inner side surface of the outer pole piece 4 is coated with positive electrode paste.

[0027] In the embodiment of the present utility model, the positive electrode sheet 1, the negative electrode sheet 2, the separator 3, and the outer ring electrode sheet 4 are all strip-shaped structures with the same length and width. Before winding, they are stacked in the order of one layer of positive electrode sheet 1, one layer of separator 3, and one layer of negative electrode sheet 2, and then wound according to the conventional production process to form a winding core body a structure with the negative electrode sheet 2 wrapping the positive electrode sheet 1 on the outermost layer. On this basis, by additionally arranging an outer ring electrode sheet 4 around the outer layer of the winding core body a, the outer ring electrode sheet 4 adopts a single-sided coating process, and the same positive electrode paste as that on the positive electrode sheet 1 is coated only on the inner side surface, that is, the side surface surrounding and facing the winding core body a, so as to make the outermost layer of the final winding core be the positive electrode sheet. The winding core structure made by this process forms a monomer battery cell after being put into the shell and completing the over-current connection and starts to work. The outer wrapping of the positive electrode sheet 1 of the winding core body a ensures that after the aluminum shell and the winding core body a form an electronic path through metal particles and dropped electrode sheet metal powder, it is the positive electrode that is connected to the aluminum shell instead of the negative electrode, and the positive electrode sheet 1 is connected to the aluminum shell, avoiding the electrochemical corrosion caused by the connection between the aluminum shell and the negative electrode sheet 2, which results in the potential dropping below the lithium insertion potential. Thus, the problems of insufficient battery life and potential safety hazards caused by defects in the internal winding core setting in the related art are solved.

[0028] Optionally, a plurality of coating areas 41 are evenly spaced along the winding direction on the outer ring electrode sheet 4, and the positive electrode paste is coated on the coating areas 41. Exemplarily, in the embodiment of the present utility model, the outer ring electrode sheet 4 is a strip-shaped structure in the shape of a cuboid, the coating areas 41 are strip-shaped and arranged along the width direction of the outer ring electrode sheet 4, and the plurality of coating areas 41 are arranged in parallel at intervals along the length direction of the outer ring electrode sheet 4. During production, the width direction of the outer ring electrode sheet 4 can be used as the coating direction of the coating areas 41, that is, multiple polar pastes are simultaneously coated on the current collector substrate to form the coating areas 41, and then cut at one time according to actual use requirements to form strip-shaped electrode sheets, with high production efficiency. Further, when the outer ring electrode sheet 4 is used, to ensure that the outermost layer is the positive electrode and no lithium precipitation occurs during the operation of the battery cell, the outermost layer of the outer ring electrode sheet 4 adopts single-layer intermittent coating, and the gap width between the coating areas 41 is jointly determined by the discharge capacities of the positive and negative electrodes, the proportion of the main materials of the positive and negative electrodes, and the rolling densities of the positive and negative electrodes. It should be ensured that the discharge N / P ratio is greater than 1.13 (discharge N / P ratio = negative electrode discharge gram capacity (mAh / g) * proportion of negative electrode main material * negative electrode rolling surface density (g / m2) / positive electrode discharge gram capacity (mAh / g) * proportion of positive electrode main material * positive electrode rolling surface density (g / m2)), so as to achieve the purpose of reducing lithium precipitation.

[0029] Optionally, the spacing range of the coating areas 41 is from 3 mm to 5 cm. Exemplarily, in the embodiments of the present invention, the applicant has obtained the above spacing range of the coating areas 41 through a large number of usage tests, and the number of gaps on the outer ring electrode tab 4 is at least one, which is applicable to the square shell lithium battery cells with conventional sizes in a new energy vehicle battery pack. While ensuring the production cost, the risk of electrochemical corrosion of the cell housing is minimized to the greatest extent.

[0030] Optionally, a separator 3 is also disposed around the outer side of the outer ring electrode tab 4. Exemplarily, in the embodiments of the present invention, by also disposing a separator 3 around the outer side of the outer ring electrode tab 4, the integrity of the core body a of the wound core is improved, and it can also prevent the area where the outer ring electrode tab 4 may be coated with the slurry from directly contacting the cell housing or the pole post to cause a short circuit, further improving the working safety.

[0031] Optionally, in the winding direction, the positive electrode sheet 1, the negative electrode sheet 2, and the separator 3 are provided with multiple segments. Exemplarily, in the embodiments of the present invention, based on the number of winding turns and the thickness of the core body a of the wound core, the positive electrode sheet 1, the negative electrode sheet 2, and the separator 3 can be stacked in multiple independent segments in an alternating manner for winding to form the final wound core body a that meets the specification dimensions. Referring to Figure X, the wound core body a in the embodiments of the present invention is wound from two-section structures. It can effectively reduce the lengths of the electrode tabs and the separator, facilitate preparation and cutting, reduce the production cost, and improve the production efficiency.

[0032] The embodiments of the present invention also provide a battery cell, including as Figures 1 to 5The shown core structure further includes a cover plate 5 and a lower housing 6. The core structure is disposed within the lower housing 6, and the cover plate 5 is covered on the lower housing 6. A pole column 51 is provided on the cover plate 5, and the pole column 51 is connected to the tab end of the core body a of the core. An insulating plastic part 52 is provided between the pole column 51 and the cover plate 5. By using the core structure provided by the embodiment of the present utility model, in cooperation with the cover plate 5 and the lower housing 6 to form a single cell, by additionally surrounding an outer ring electrode sheet 4 around the outer layer of the core body wound by the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 in conventional production. The outer ring electrode sheet 4 adopts a single-sided coating process, and only the same positive electrode paste as that on the positive electrode sheet 1 is coated on the inner side surface, that is, the side surface surrounding and facing the core body a of the core, so as to realize that the outermost layer of the final core is the positive electrode sheet. The core structure made by this process forms a single cell through overcurrent connection after being put into the shell and works. The outer wrapping of the positive electrode sheet 1 of the core body a of the core ensures that after the aluminum shell and the core body a of the core form an electronic path through metal particles and dropped electrode sheet metal powder, it is the positive electrode that is connected to the aluminum shell instead of the negative electrode. The positive electrode sheet 1 is connected to the aluminum shell, avoiding the connection between the aluminum shell and the negative electrode sheet 2, which may cause electrochemical corrosion due to the potential dropping below the lithium insertion potential. Thus, the problems of insufficient battery life and potential safety hazards caused by defects in the internal core setting in the related art are solved.

[0033] Further, by providing an insulating plastic part 52 at the installation position of the pole column 51 on the cover plate 5 to insulate the pole column 51, the aluminum shell structure composed of the cover plate 5 and the lower housing 6 can be made to have a non-charged surface before forming an electronic path with the core body a during normal operation, thereby reducing the self-decay of the capacity of the single cell, avoiding the influence on other electronic devices due to charging, improving the overall battery life, and also reducing the possibility of safety risks in special environments such as humidity.

[0034] Optionally, the insulating plastic part 52 is in a cylindrical shape and sleeved outside the pole column 51, and the cover plate 5 is provided with an installation hole 53 that matches the outer contour of the insulating plastic part 52. Exemplarily, in the embodiment of the present utility model, the insulating plastic part 52 can be tightly sleeved outside the independent pole column 51 through its flexible characteristics, and then installed into the special-shaped installation hole 53 on the cover plate 5 by pressing and embedding. The insulating plastic part 52 is used to fill the gap between the pole column 51 and the installation hole 53 to achieve insulation isolation and firm installation. Each component can be produced and prepared separately, and the combination method is simple, which can effectively improve the production and assembly efficiency.

[0035] Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present utility model pertains. The terms "first", "second" and similar terms used in the description and claims of the patent application for the present utility model do not denote any order, quantity or importance, but are merely used to distinguish different components. Similarly, terms such as "a" or "an" do not denote a limitation of quantity, but rather denote the presence of at least one. The terms "comprising" or "including" and similar terms mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalents, and do not exclude other elements or items. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationships may also change accordingly.

[0036] The above are only optional embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A core structure, characterized in that, Comprising: a positive electrode sheet (1), a negative electrode sheet (2), a separator (3), and an outer ring electrode sheet (4), the positive electrode sheet (1), the separator (3), and the negative electrode sheet (2) are sequentially stacked and wound to form a core body (a), the outer ring electrode sheet (4) is disposed around the outer periphery of the core body (a), and a positive electrode paste is coated on the inner side surface of the outer ring electrode sheet (4).

2. The core structure according to claim 1, characterized in that, A plurality of coating areas (41) are uniformly spaced along the winding direction on the outer ring electrode sheet (4), and the positive electrode paste is coated on the coating areas (41).

3. A core structure according to claim 2, characterized in that, The outer ring electrode sheet (4) is in a cuboid shape, the coating areas (41) are in a strip shape and are arranged along the width direction of the outer ring electrode sheet (4), and the plurality of coating areas (41) are arranged in parallel and spaced along the length direction of the outer ring electrode sheet (4).

4. A core structure according to claim 3, characterized in that, The spacing range of the coating areas (41) is from 3 mm to 5 cm.

5. A core structure according to any one of claims 1 to 4, characterized in that, The separator (3) is also disposed around the outer side surface of the outer ring electrode sheet (4).

6. A core structure according to any one of claims 1 to 4, characterized in that, In the winding direction, the positive electrode sheet (1), the negative electrode sheet (2), and the separator (3) are provided with a plurality of segments.

7. A double-insulated pole column (51) battery cell, comprising the wound core structure according to any one of claims 1 to 6, characterized in that, It further includes a cover plate (5) and a lower housing (6), the core structure is disposed in the lower housing (6), the cover plate (5) is covered on the lower housing (6), a pole column (51) is provided on the cover plate (5), the pole column (51) is connected to the tab end of the core body (a), and an insulating plastic part (52) is disposed between the pole column (51) and the cover plate (5).

8. The double-insulated pole column (51) battery cell according to claim 7, characterized in that, The insulating plastic part (52) is in a cylindrical shape and is sleeved on the outer side of the pole column (51), and a mounting hole (53) matching the outer contour of the insulating plastic part (52) is provided on the cover plate (5).

Images