C-shaped roll core, square lithium ion battery and electric equipment

Abstract

The utility model discloses a C-shaped roll core, a square lithium ion battery and electric equipment, and belongs to the technical field of lithium ion battery, the C-shaped roll core comprises diaphragms and pole pieces, the diaphragms and the pole pieces are alternately stacked in one direction, and the diaphragms and the pole pieces are alternately stacked in time sequence. The length of the diaphragms or pole pieces stacked later is gradually decreased or increased relative to the length of the diaphragms or pole pieces stacked later, the diaphragms and the pole pieces are sequentially stacked to form a stacked structure, the stacked structure is rolled or bent along the center of the shortest pole piece in the length direction to form a C-shaped roll-shaped structure, and at least one side of the C-shaped roll-shaped structure is of a flush structure. The square lithium ion battery comprises a square shell and the C-shaped roll core, the C-shaped roll core is placed in the square shell, and the square shell is filled with electrolyte. Compared with a battery core with a traditional roll core structure, the battery core disclosed by the utility model can reduce the assembly clearance between the stacked roll core and the square shell, is more matched with the square shell, and improves the energy density of the battery.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium - ion batteries, and specifically to a C - shaped laminated winding core, a square lithium - ion battery and an electrical equipment. Background Art

[0002] As an important energy - carrier tool, lithium - ion batteries have been widely used in various industries. The existing core production technologies are divided into two categories. One is the winding core produced by the winding method. The biggest advantage of the winding core production method is that it can be continuously wound and produced, with a high production speed. The other is the laminated structure, whose square structure better occupies the space of the square shell, and its energy density has a significant increase compared with the winding structure. However, the laminated core is limited by the reciprocating stacking of the separator and the electrode structure, and its production efficiency is relatively slow.

[0003] For example, the Chinese patent document with the publication number CN205543092U discloses a lithium - ion battery, including a negative electrode tab and a positive electrode tab. The negative electrode tab is connected with a negative copper foil, and the positive electrode tab is connected with a positive aluminum foil. A separator is arranged between the negative copper and the positive aluminum foil. One side of the separator is wound along the surface of the negative copper foil to form a negative - electrode wrapping layer, and the other side of the separator is wound along the surface of the positive aluminum foil to form a positive - electrode wrapping layer. The negative - electrode wrapping layer and the positive - electrode wrapping layer are superposed to form a winding core. Although this lithium - ion battery can ensure the accuracy of the tab center distance, improve the quality of the winding core, and has a high production efficiency; however, both sides of the winding core of this lithium - ion battery are semi - circular arc edges, and there will be a large gap with the space of the square shell during assembly, and the energy density is relatively low. How to achieve the balance between the production efficiency and the energy density of the battery is an urgent problem to be solved for the further development of lithium - ion batteries. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a C - shaped laminated winding core, a square lithium - ion battery and an electrical equipment, so as to solve the problem that there is a large gap between the winding core and the square shell during assembly in the prior art, resulting in a relatively low energy density.

[0005] To achieve the above purpose, the utility model provides a C - shaped laminated winding core, including a separator and electrode sheets. The separator and the electrode sheets are alternately stacked in one direction. In the chronological order, the length of the later - stacked separator or electrode sheet is decreased or increased relative to the separator or electrode sheet stacked earlier. The separator and the electrode sheets are stacked successively to form a stacked structure, and the stacked structure is rolled or bent along the center of the shortest length direction of the electrode sheet to form a C - shaped rolled structure, and at least one side of the C - shaped rolled structure is a flat structure.

[0006] Through the above technical solution, the stacked structure is rolled or bent along the center in the length direction of the electrode sheet to form a C-shaped rolled structure. If at least one side of the rolled structure is a flat structure, it can fit well with the square battery case, effectively occupy the space inside the square case, and contribute to improving the battery energy density. The rolled core structure is formed by the process of stacking first and then rolling, which improves the production efficiency compared with the traditional core stacking process.

[0007] Further, the electrode sheet includes a negative electrode sheet and a positive electrode sheet. The stacked structure is sequentially stacked in the order of separator, negative electrode sheet, separator, and positive electrode sheet. The outermost side of the C-shaped rolled structure is a separator.

[0008] Sequential stacking makes the outermost side of the C-shaped rolled structure a separator. After rolling, the negative electrode sheet can cover the outside of the positive electrode sheet, enabling the lithium ions of the positive electrode sheet to migrate to the negative electrode sheet and preventing the precipitation of lithium ions.

[0009] Further, the area of the negative electrode sheet is larger than that of the positive electrode sheet. In the C-shaped rolled structure, the negative electrode sheet covers the positive electrode sheet.

[0010] The larger area of the negative electrode sheet than that of the positive electrode sheet allows the negative electrode sheet to have sufficient space to accommodate the migrated lithium ions, further preventing the phenomenon of lithium precipitation.

[0011] Further, the separator is a porous membrane structure, and the separator is a continuous structure or a single-piece structure.

[0012] The porous membrane structure facilitates the migration of lithium ions, and the continuous or single-piece structure of the separator can adapt to different production and processing scenarios.

[0013] Further, the C-shaped rolled structure includes two opening segments, one bending segment, and two transition segments. The two opening segments are symmetric about the midline in the length direction of the electrode sheet. The opening segments are connected to the bending segment through the transition segments. The bending segment appears straight when observed from one side, and the transition segment appears arc-shaped when observed from the same side.

[0014] Through the above structural design, the end faces of the two opening segments are aligned up and down to form a flat surface, and the end face of the bending segment also forms a flat surface. That is, the two sides of the C-shaped rolled structure are flat structures, which can better fit the lithium-ion battery with a square case and are beneficial to improving the energy density of the lithium-ion battery.

[0015] Further, the C-shaped rolled structure includes two opening segments and one bending segment. The two opening segments are symmetric about the midline in the length direction of the electrode sheet. The two opening segments are connected by the bending segment. The bending segment appears arc-shaped when observed from one side.

[0016] Similarly, the end faces of the two open segments are aligned up and down to form a flat surface. That is to say, compared with the traditional core structure, one side of the C-shaped rolled structure is a flat structure, which can also fit well with the internal structure of the square shell battery, reduce the cavity and thus improve the energy density of the lithium-ion battery.

[0017] Further, a negative electrode tab and a positive electrode tab are respectively arranged on the negative electrode sheet and the positive electrode sheet, and the negative electrode tab and the positive electrode tab are located on the same rolling side or bending side of the C-shaped rolled structure.

[0018] The negative electrode tab and the positive electrode tab are located on the same side of the C-shaped rolled structure, which can ensure good alignment of the electrode tabs during the production of the battery cell.

[0019] Further, the negative electrode tab and the positive electrode tab are located on different rolling sides or bending sides of the C-shaped rolled structure.

[0020] The negative electrode tab and the positive electrode tab are located on different sides of the C-shaped rolled structure, which can increase the adaptability of the battery cell assembly, be suitable for different assembly scenarios, and improve the adaptability of the battery cell.

[0021] The present utility model also provides a square lithium-ion battery, which includes a square shell and the above-mentioned C-shaped stacked core. The C-shaped stacked core is placed in the square shell, and the square shell is filled with electrolyte.

[0022] The present utility model also provides an electrical equipment, which includes the above-mentioned square lithium-ion battery.

[0023] Adopting the technical solution provided by the present utility model, compared with the existing well-known technology, it has the following beneficial effects:

[0024] (1) For a C-shaped stacked core of the present utility model, the length of the diaphragm and the electrode sheet stacked later is decreasing or increasing relative to the diaphragm and the electrode sheet stacked earlier, so that the stacked structure formed by stacking the diaphragm and the electrode sheet successively is trapezoidal when observed from one side. The stacked structure is rolled or bent along the center of the length direction of the electrode sheet to form a C-shaped rolled structure. If at least one side of the rolled structure is a flat structure, it can fit well with the square battery shell, effectively occupy the space inside the square shell, and contribute to improving the battery energy density. By forming the core structure through the process of stacking first and then rolling, the production efficiency is improved compared with the traditional stacking core process.

[0025] (2) For a C-shaped stacked core of the present utility model, the diaphragm, the negative electrode sheet, the diaphragm, and the positive electrode sheet are stacked in sequence. The outermost side of the C-shaped rolled structure is the diaphragm, so that the rolled negative electrode sheet can cover the outside of the positive electrode sheet, enabling the lithium ions of the positive electrode sheet to migrate to the negative electrode sheet and preventing the precipitation of lithium ions. The area of the negative electrode sheet is larger than that of the positive electrode sheet, so that the negative electrode sheet has enough space to accommodate the migrated lithium ions, further preventing the phenomenon of lithium precipitation.

[0026] Obviously, the elements or features described in the above single embodiment can be used alone or in combination in other embodiments. Description of the Drawings

[0027] In the drawings, the dimensions and proportions do not represent the dimensions and proportions of the actual product. The drawings are merely illustrative, and for clarity, some non-essential elements or features are omitted.

[0028] Figure 1 is a schematic structural view (one) of the C-shaped stacked winding core according to an embodiment of the present invention;

[0029] Figure 2 is a schematic structural view (two) of the C-shaped stacked winding core according to an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram (one) of the C-shaped stacked winding core according to an embodiment of the present invention;

[0031] Figure 4 is a schematic structural diagram (two) of the C-shaped stacked winding core according to an embodiment of the present invention.

[0032] Description of the Reference Numerals

[0033] 11. Opening section; 12. Bending and pressing section; 13. Transition section; 100. Diaphragm; 200. Negative electrode sheet; 210. Negative electrode tab; 300. Positive electrode sheet; 310. Positive electrode tab. Detailed Embodiments

[0034] Next, the present invention will be described in detail with reference to the drawings. What is described here is only the preferred embodiment according to the present invention, and those skilled in the art can think of other ways to implement the present invention on the basis of the preferred embodiment, and other ways also fall within the scope of the present invention.

[0035] Embodiment

[0036] Refer to Figures 1 - 4, this embodiment provides a C-shaped laminated core, which includes a separator 100 and electrode sheets. The separator 100 and the electrode sheets are alternately stacked in one direction. In chronological order, the length of the later-stacked separator 100 or electrode sheet is decreased or increased relative to the length of the prior separator 100 or electrode sheet, so that the stacked structure formed by the sequential stacking of the separator 100 and the electrode sheets presents a trapezoidal shape when viewed from one side. Taking the stacking from bottom to top as an example, when the length of the later-stacked separator 100 or electrode sheet is decreased relative to the length of the prior separator 100 or electrode sheet, the trapezoidal shape is smaller at the top and larger at the bottom; when the length of the later-stacked separator 100 or electrode sheet is increased relative to the length of the prior separator 100 or electrode sheet, the trapezoidal shape is larger at the top and smaller at the bottom. The separator 100 and the electrode sheets are sequentially stacked to form a stacked structure, and the stacked structure is rolled or bent along the center of the shortest length direction of the electrode sheet to form a C-shaped rolled structure, and at least one side of the C-shaped rolled structure is a flush structure. As Figure 1 and Figure 2 shown, the opening side of the C-shaped rolled structure after rolling or bending presents a flush structure up and down. This flush structure can well fit the square battery case, effectively occupy the space inside the square case, and help improve the battery energy density. Moreover, by forming the core structure through the process of stacking first and then rolling, the production efficiency is improved compared with the traditional laminated core process.

[0037] Specifically, in this embodiment, please refer to Figure 1 and Figure 2 , the electrode sheets include a negative electrode sheet 200 and a positive electrode sheet 300. The stacked structure is sequentially stacked in the order of separator 100, negative electrode sheet 200, separator 100, and positive electrode sheet 300, and the outermost side of the C-shaped rolled structure is the separator 100. In the C-shaped rolled structure formed by bending or rolling the stacked structure formed in the above order, the negative electrode sheet 200 can cover the outside of the positive electrode sheet 300, so that the lithium ions of the positive electrode sheet 300 can migrate to the negative electrode sheet 200 to prevent the precipitation of lithium ions.

[0038] Furthermore, the area of the negative electrode sheet 200 is larger than the area of the positive electrode sheet 300, and in the C-shaped rolled structure, the negative electrode sheet 200 covers the positive electrode sheet 300. The relatively larger area of the negative electrode sheet 200 can provide sufficient accommodation space for the lithium ions migrating from the positive electrode sheet 300, further avoiding the phenomenon of lithium precipitation. It should be noted that the separator 100 is a porous membrane structure, and the separator 100 is designed as a continuous structure and a single-piece structure. When the separator 100 is a continuous structure, it is cross-stacked with the positive electrode sheet 300 and the negative electrode sheet 200 through the "Z"-type laminating technology. Since the components of the electrolyte include organic solvents, the separator 100 needs to be made of a material resistant to organic solvents, and generally a high-strength thin-film polyolefin porous membrane is used.

[0039] To facilitate the understanding of the C-shaped rolled structure after rolling or bending, in this embodiment, the C-shaped rolled structure is simplified. One of the simplified structures is asFigure 3 As shown, the C-shaped coiled structure includes two open segments 11, one bending and pressing segment 12, and two transition segments 13. The two open segments 11 are symmetric about the midline in the length direction of the electrode tab. The open segments 11 are connected to the bending and pressing segment 12 through the transition segments 13. The bending and pressing segment 12 is linear when observed from one side, and the transition segments 13 are arc-shaped when observed from the same side. The end faces of the two open segments 11 are aligned vertically to form a flat surface. The bending and pressing segment 12 is also linear when observed from one side, that is, the end face of the bending and pressing segment 12 also forms a flat surface. The two side faces of the C-shaped coiled structure in this embodiment are flat structures, which can better fit the lithium-ion battery with a square case, and is beneficial to improving the energy density of the lithium-ion battery.

[0040] In this embodiment, another simplified structure of the C-shaped coiled structure is as Figure 4 shown. The C-shaped coiled structure includes two open segments 11 and one bending and pressing segment 12. The two open segments 11 are symmetric about the midline in the length direction of the electrode tab. The two open segments 11 are connected by the bending and pressing segment 12. The bending and pressing segment 12 is arc-shaped when observed from one side. Similarly, the end faces of the two open segments 11 are aligned vertically to form a flat surface. That is to say, compared with the traditional coiled core structure, at least one side face of the C-shaped coiled structure in this embodiment is a flat structure, which can also well fit the internal structure of the square case battery, reduce the cavity, and thus improve the energy density of the lithium-ion battery.

[0041] The electrode tab is usually provided on the electrode. The electrode tab is a metal conductor that leads out the positive and negative electrodes from the battery cell. In this embodiment, a negative electrode tab 210 and a positive electrode tab 310 are respectively provided on the negative electrode sheet 200 and the positive electrode sheet 300. As Figure 1 shown, the negative electrode tab 210 and the positive electrode tab 310 are located on the same coiling or bending side of the C-shaped coiled structure, that is, both the negative electrode tab 210 and the positive electrode tab 310 are located on the upper side of the C-shaped coiled structure. When the negative electrode tab 210 and the positive electrode tab 310 are located on the same coiling or bending side of the C-shaped coiled structure, good alignment of the electrode tabs can be achieved during production. Of course, both the negative electrode tab 210 and the positive electrode tab 310 can also be located on the lower side of the C-shaped coiled structure. The positions where the electrode tabs are provided are not unique and can also be set at other positions. In this embodiment, as Figure 2 shown, the negative electrode tab 210 and the positive electrode tab 310 are located on different coiling or bending sides of the C-shaped coiled structure, that is, the negative electrode tab 210 is located on the lower side of the C-shaped coiled structure, and the positive electrode tab 310 is located on the upper side of the C-shaped coiled structure. Similarly, the negative electrode tab 210 can also be located on the upper side of the C-shaped coiled structure, and the positive electrode tab 310 is located on the lower side of the C-shaped coiled structure.

[0042] This application also provides a square lithium-ion battery, including a square case and the above-mentioned C-shaped stacked coiled core. The C-shaped stacked coiled core is placed in the square case, and the square case is filled with electrolyte.

[0043] The present application also provides an electrical device, including the above-mentioned square lithium-ion battery.

[0044] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", "upper", "lower", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0045] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0046] The protection scope of the present utility model is only defined by the claims. Benefiting from the teachings of the present utility model, those skilled in the art can easily recognize that alternative structures of the structures disclosed in the present utility model can be used as feasible alternative embodiments, and the embodiments disclosed in the present utility model can be combined to produce new embodiments, which also fall within the scope of the appended claims.

Claims

1. A C-shaped stacked core, comprising a diaphragm (100) and a pole piece, wherein the diaphragm (100) and the pole piece are alternately stacked in one direction, characterized in that: In time sequence, the length of the later stacked diaphragm (100) or pole piece decreases or increases relative to the earlier diaphragm (100) or pole piece, and the diaphragm (100) and pole piece are stacked in sequence to form a stacked structure, and the stacked structure is rolled or bent along the center of the shortest pole piece length direction to form a C-shaped rolled structure, and at least one side of the C-shaped rolled structure is a flush structure.

2. A C-shaped stacking core according to claim 1, characterized in that: The electrode sheets include a negative electrode sheet (200) and a positive electrode sheet (300), and the stacked structure is stacked in the order of a separator (100), a negative electrode sheet (200), a separator (100), and a positive electrode sheet (300), and the outermost side of the C-shaped rolled structure is the separator (100).

3. A C-shaped stacking core according to claim 2, characterized in that: The area of ​​the negative electrode sheet (200) is greater than that of the positive electrode sheet (300), and in the C-shaped rolled structure, the negative electrode sheet (200) covers the positive electrode sheet (300).

4. The C-shaped stacking core according to claim 1, characterized in that: The diaphragm (100) is a porous membrane structure, and the diaphragm (100) is a continuous structure or a single-piece structure.

5. The C-shaped stacking core according to claim 1, characterized in that: The C-shaped rolled structure comprises two opening sections (11), a bending section (12) and two transition sections (13); the two opening sections (11) are symmetrical about the midline of the pole piece length direction; the opening section (11) is connected to the bending section (12) via the transition section (13); the bending section (12) is straight-lined when viewed from one side, and the transition section (13) is arc-shaped when viewed from the same side.

6. The C-shaped stacking core according to claim 1, characterized in that: The C-shaped rolled structure comprises two opening sections (11) and a bending section (12); the two opening sections (11) are symmetrical about the midline of the pole piece length direction; the two opening sections (11) are connected via the bending section (12); and the bending section (12) is arc-shaped when viewed from one side.

7. The C-shaped stacking core according to claim 2, characterized in that: The negative electrode sheet (200) and the positive electrode sheet (300) are respectively provided with a negative electrode tab (210) and a positive electrode tab (310), and the negative electrode tab (210) and the positive electrode tab (310) are located on the same rolled side or bent side of the C-shaped rolled structure.

8. The C-shaped stacking core according to claim 7, characterized in that: The negative electrode tab (210) and the positive electrode tab (310) are located on different rolled sides or bent sides of the C-shaped rolled structure.

9. A square lithium-ion battery, characterized in that: It comprises a square shell and the C-shaped stacked core according to any one of claims 1 to 8, wherein the C-shaped stacked core is placed in the square shell, and the square shell is filled with electrolyte.

10. An electrical device, characterized in that: Including the square lithium-ion battery as described in claim 9.

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