Roll core for improving head lithium precipitation, lithium ion battery and electric equipment

Abstract

The utility model discloses a roll core for improving head lithium precipitation, a lithium ion battery and electric equipment. The roll core comprises a cathode pole piece, a diaphragm and an anode pole piece which are sequentially stacked and formed by winding. The part of the anode pole piece on the innermost ring is bent towards the direction far away from the roll core to form an inflection part; and the inflection part abuts against the anode pole piece and / or the diaphragm around the inflection part. The design can effectively reduce and even avoid lithium separation of the anode plate in the inner ring, so that the cycle life performance of the lithium ion battery is ensured.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a winding core, a lithium-ion battery, and an electrical device for improving lithium deposition on the head. Background Art

[0002] Lithium-ion batteries are widely used in various digital products and mobile devices due to their advantages such as high energy density, low self-discharge, wide operating temperature range and no environmental pollution.

[0003] A wound lithium-ion battery is a common structure. The core of a wound lithium-ion battery includes a cathode electrode sheet, a separator and an anode electrode sheet, and the cathode electrode sheet, the separator and the anode electrode sheet are wound to form a core.

[0004] However, due to the structural limitations of the winding core of the wound lithium-ion battery in the related art, with the continuous increase in charging rate and the continuous consumption of electrolyte, the cathode and anode electrodes in the inner circle of the winding core are not sufficiently fitted together, resulting in abnormal conditions such as lithium deposition on the electrodes in the inner circle of the winding core, which affects the life of the wound lithium-ion battery. Utility Model Content

[0005] The embodiments of the present application provide a winding core, a lithium-ion battery, and an electrical device for improving lithium deposition on the head, which can solve the problem in the related art that the cathode and anode electrodes in the inner circle of the winding core are not sufficiently fitted together due to factors such as the continuous increase in charging rate and the continuous consumption of electrolyte, resulting in abnormal conditions such as lithium deposition on the electrodes in the inner circle of the winding core.

[0006] In the first aspect, an embodiment of the present application provides a winding core for improving lithium deposition on the head; the winding core includes a cathode electrode, a diaphragm and an anode electrode stacked and wound in sequence, and a portion of the innermost anode electrode is bent away from the winding core to form a folded portion, and the folded portion abuts against the anode electrode and / or diaphragm around it.

[0007] Based on the winding core with improved head lithium deposition in the embodiment of the present application, a folded portion is formed by bending part of the innermost circle of the anode electrode sheet in a direction away from the winding axis of the winding core. The folded portion can provide outward tension and squeeze the anode electrode sheet and / or diaphragm in contact with it, so that the anode electrode sheet and the cathode electrode sheet located in the inner circle are more closely fitted, which can effectively reduce or even avoid the possibility of lithium deposition in the anode electrode sheet located in the inner circle.

[0008] In a second aspect, an embodiment of the present application provides a lithium-ion battery; the lithium-ion battery includes a shell, an electrolyte and the above-mentioned winding core, the shell has a receiving cavity, the electrolyte is poured into the receiving cavity of the shell, and the above-mentioned winding core is arranged in the receiving cavity of the shell.

[0009] The lithium-ion battery according to the embodiment of the present application has the above-mentioned winding core, which can effectively reduce or even avoid lithium plating of the anode electrode located in the inner circle, so as to ensure the cycle life performance of the lithium-ion battery.

[0010] In a third aspect, an embodiment of the present application provides an electrical device; the electrical device includes a housing and the above-mentioned lithium-ion battery, the housing has a battery mounting slot, and the lithium-ion battery is mounted on the housing corresponding to the battery mounting slot.

[0011] The electrical equipment according to the embodiment of the present application is equipped with the above-mentioned lithium-ion battery, which can effectively reduce or even avoid lithium plating of the anode electrode located in the inner circle, ensure the cycle life performance of the lithium-ion battery, and thus improve the service life of the electrical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 This is a schematic structural diagram of a winding core in one embodiment of the present application;

[0014] Figure 2 This is a schematic structural diagram of an anode electrode in one embodiment of the present application;

[0015] Figure 3 This is a schematic structural diagram of a cathode electrode in one embodiment of the present application;

[0016] Figure 4 This is a schematic structural diagram of an anode electrode in another embodiment of the present application.

[0017] Reference numerals: 1, winding core; 10, cathode electrode; 20, anode electrode; 21, folded portion; 211, first folded portion; 212, second folded portion; 22, non-folded portion. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0019] Lithium-ion batteries are widely used in various digital products and mobile devices due to their advantages such as high energy density, low self-discharge, wide operating temperature range and no environmental pollution.

[0020] A wound lithium-ion battery is a common structure. The core of a wound lithium-ion battery includes a cathode electrode sheet, a separator and an anode electrode sheet, and the cathode electrode sheet, the separator and the anode electrode sheet are wound to form a core.

[0021] However, due to the structural limitations of the winding core of the wound lithium-ion battery in the related art, with the continuous increase in charging rate and the continuous consumption of electrolyte, the cathode and anode electrodes in the inner circle of the winding core are not sufficiently fitted together, resulting in abnormal conditions such as lithium deposition on the electrodes in the inner circle of the winding core, which affects the life of the wound lithium-ion battery.

[0022] To solve the above problems, please refer to Figure 1-Figure 3 As shown, in the first aspect, the present application proposes a winding core 1 for improving lithium deposition at the head, which can reduce or even avoid lithium deposition at the anode electrode 20 located at the inner circle, so as to ensure the cycle life performance of the lithium-ion battery.

[0023] The winding core 1 includes a cathode electrode 10, a separator (not shown), and an anode electrode 20 stacked and wound in sequence. The innermost anode electrode 20 is bent away from the winding core 1 to form a fold 21, which abuts against the surrounding anode electrode 20 and / or separator.

[0024] The following combination Figures 1-4 The specific structure of the winding core 1 is introduced in detail; the winding core 1 includes a cathode electrode 10, a separator and an anode electrode 20.

[0025] like Figure 1-Figure 3 As shown, the cathode electrode sheet 10 serves as one electrode of the winding core 1 ; the cathode electrode sheet 10 includes another current collector and another active material layer applied on its surface.

[0026] Another current collector serves as a component for collecting current in the cathode electrode 10. Its main function is to carry another active material layer, collect the current generated by the chemical reaction of the other active material layer to form a larger current and output it to the outside, thereby completing the conversion process of chemical energy into electrical energy.

[0027] The other active material layer serves as a component in the cathode electrode 10 for chemically reacting with the electrolyte in the lithium-ion battery to generate current; the component of the other active material layer is graphene.

[0028] The diaphragm serves as an insulating part of the winding core 1 and is used to separate the cathode electrode 10 and the anode electrode 20 to prevent the cathode electrode 10 from contacting the anode electrode 20 and causing a short circuit. There is no limitation on the specific material of the diaphragm, and designers can make a reasonable choice based on actual needs. For example, the material of the diaphragm can be, but is not limited to, polyethylene (PE), polypropylene (PP), etc.

[0029] The anode plate 20 serves as another electrode of the winding core 1 ; the anode plate 20 includes a current collector and an active material layer applied on its surface.

[0030] The current collector is a component that collects current in the anode electrode 20. Its main function is to carry the active material layer, collect the current generated by the chemical reaction of the active material layer to form a larger current and output it to the outside, thereby completing the conversion process of chemical energy into electrical energy.

[0031] The active material layer is a component in the anode electrode 20 that is used to chemically react with the electrolyte in the lithium-ion battery to generate current; the component of the active material layer is NCM material, which includes at least one of NCM7205, NCM811 and NCM9005; and the mass fraction of each component of the active material layer can be but is not limited to: 92%-97% of the ternary positive electrode material, 1%-4% of the conductive agent, and 1%-4% of the binder.

[0032] like Figure 1-Figure 3 As shown, the anode electrode sheet 20 is in the innermost layer, and the anode electrode sheet 20, the separator and the cathode electrode sheet 10 are stacked in sequence and wound into a winding core 1.

[0033] The innermost portion of the anode plate 20 is bent away from the winding core 1 (specifically, away from the winding axis of the winding core 1) to form a folded portion 21. Specifically, the folded portion 21 is formed by bending the innermost portion of the anode plate 20 away from the winding axis of the winding core 1. The specific shape of the folded portion 21 is not limited here; designers can design it appropriately based on actual needs. For example, the cross-section of the folded portion 21 in a plane perpendicular to the winding axis of the winding core 1 can be, but is not limited to, a C-shape or an L-shape.

[0034] The folded portion 21 abuts against the anode pole piece 20 and / or diaphragm around it. For example, the folded portion 21 may only abut against the anode pole piece 20 around it; for another example, the folded portion 21 may only abut against the diaphragm; for another example, the folded portion 21 may also partially abut against the anode pole piece 20 around it and the remaining part abut against the diaphragm. It should be noted that different contact forms such as point contact, line contact or surface contact can be formed between the folded portion 21 and the anode pole piece 20 and / or diaphragm around it; and it can be understood that for folded portions 21 of different shapes, the specific contact forms between the folded portions 21 of different shapes and the anode pole piece 20 and / or diaphragm around them are also different.

[0035] Based on the winding core 1 in the embodiment of the present application, a folded portion 21 is formed by bending a portion of the innermost circle of the anode electrode 20 in a direction away from the winding axis of the winding core. The folded portion 21 can provide outward tension and squeeze the anode electrode 20 and / or diaphragm in contact therewith, so that the anode electrode 20 located in the inner circle is more closely fitted to the cathode electrode 10, which can effectively reduce or even avoid the possibility of lithium deposition in the anode electrode 20 located in the inner circle.

[0036] like Figure 1-Figure 2 As shown, the innermost anode plate 20 is bent from its starting end away from the winding core 1 to form a folded portion 21. By bending the starting end of the innermost anode plate 20 away from the winding axis of the winding core 1 to form the folded portion 21, the difficulty of processing the folded portion 21 can be effectively reduced. Figure 4 As shown, in other embodiments, the folded portion 21 may be formed by bending from other positions of the innermost anode electrode sheet 20 except the starting end in a direction away from the winding core 1 .

[0037] like Figure 1-Figure 2 As shown, the remaining portion of the innermost anode plate 20 is used to form the non-return portion 22. The return portion 21 includes a first return portion 211 and a second return portion 212. The first return portion 211 is bent and connected to the non-return portion 22. The second return portion 212 is bent and connected to the end of the first return portion 211 away from the non-return portion 22. The second return portion 212 and the non-return portion 22 are located on the same side of the first return portion 211. The second return portion 212 abuts against the surrounding anode plate 20 and / or separator. By designing the first fold portion 211, the first fold portion 211 is used to connect the second fold portion 212 and the non-fold portion 22, so that the second fold portion 212 is arranged in a cantilever shape; by designing the second fold portion 212, the second fold portion 212 provides outward tension and squeezes the anode electrode 20 and / or diaphragm in contact with it, so that the anode electrode 20 located in the inner circle is more fitted with the cathode electrode 10, which can effectively reduce or even avoid the possibility of lithium plating in the anode electrode 20 located in the inner circle.

[0038] like Figure 1-Figure 2As shown, the second folded portion 212 has a curvature that matches the non-folded portion 22. By designing the second folded portion 212 to have a curvature that matches the non-folded portion 22, the contact area between the second folded portion 212 and the anode electrode sheet 20 and / or separator it abuts can be increased. At this time, the second folded portion 212 provides outward tension to further fit the anode electrode sheet 20 and the cathode electrode sheet 10 located in the inner circle, which can further effectively reduce or even avoid the possibility of lithium deposition in the anode electrode sheet 20 located in the inner circle. Of course, in other embodiments, the second folded portion 212 can also have any curvature that is not compatible with the non-folded portion 22. In this case, it is sufficient as long as the second folded portion 212 forms effective contact with the surrounding anode electrode sheet 20 and / or separator.

[0039] It is understood that the fold 21 is formed by bending the innermost portion of the anode electrode 20 in a direction away from the winding axis of the winding core 1. As part of the anode electrode 20, the fold 21 includes a current collector and an active material layer applied to the surface of the current collector. This increases the thickness of the fold 21, providing greater outward tension and squeezing the anode electrode 20 and / or separator in contact with it, further confining the inner anode electrode 20 and cathode electrode 10, further effectively reducing or even preventing the possibility of lithium deposition in the inner anode electrode 20.

[0040] The thickness of the folded portion 21 is D, and D satisfies the conditional formula: 0.05 mm ≤ D ≤ 0.15 mm. For example, the specific value of the thickness D can be, but is not limited to, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or 0.15 mm, etc. By reasonably designing the value of the thickness D of the folded portion 21 and satisfying the above conditional formula, on the one hand, the thickness of the folded portion 21 is larger, which can provide greater outward tension and squeeze the anode electrode 20 and / or diaphragm in contact with it, so that the anode electrode 20 located in the inner circle is further fitted with the cathode electrode 10, which can further effectively reduce or even avoid the possibility of lithium deposition in the anode electrode 20 located in the inner circle, and on the other hand, it is convenient for the processing of the folded portion 21. It should be noted that the thickness of the non-folded portion 22 of the innermost anode electrode 20 may be the same as or different from the thickness of the folded portion 21 , and the thickness of other layers of the non-innermost anode electrode 20 may be the same as or different from the thickness of the folded portion 21 .

[0041] The length of the folded portion 21 is L, and L satisfies the conditional formula: 0.5 mm ≤ L ≤ 5 mm. For example, the specific value of the length L can be, but is not limited to, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm or 5.0 mm. By reasonably designing the value of the length L of the folded portion 21 and satisfying the above conditional formula, the folded portion 21 can provide sufficient outward tension and squeeze the anode electrode 20 and / or diaphragm in contact therewith, so that the anode electrode 20 located in the inner circle fits with the cathode electrode 10, thereby effectively reducing or even avoiding the possibility of lithium deposition in the anode electrode 20 located in the inner circle.

[0042] The radial cross-section of the innermost anode plate 20 (i.e., the cross-section perpendicular to the winding axis of the winding core 1) has a circumference C, and L and C satisfy the conditional expression: L / C ≥ 1 / 3. By rationally designing the ratio of the length L of the folded portion 21 to the radial cross-section circumference C of the innermost anode plate 20, and ensuring that the ratio satisfies the above conditional expression, the folded portion 21 can provide sufficient outward tension and compress the anode plate 20 and / or separator in contact therewith, so that the anode plate 20 located in the inner circle is in contact with the cathode plate 10, thereby effectively reducing or even preventing the possibility of lithium deposition in the inner anode plate 20.

[0043] like Figure 1-Figure 3 As shown, the winding core 1 also includes an anode tab (not shown) and a cathode tab (not shown); the anode tab is arranged in the anode empty foil area of ​​the anode and the cathode tab is arranged in the cathode empty foil area of ​​the cathode plate 10; and both the anode tab and the cathode tab are provided with tab protective glue (not shown). The tab protective glue can be made of, but is not limited to, polyethylene glycol terephthalate (PET) and acrylic acid.

[0044] In the second aspect, the present application proposes a lithium-ion battery (not shown in the figure), which includes a shell, an electrolyte and the above-mentioned core 1; the shell has a receiving cavity; the electrolyte is poured into the receiving cavity of the shell; the above-mentioned core 1 is arranged in the receiving cavity of the shell.

[0045] The lithium-ion battery in the embodiment of the present application has the above-mentioned winding core 1, which can effectively reduce or even avoid lithium plating of the anode electrode 20 located in the inner circle, thereby ensuring the cycle life performance of the lithium-ion battery.

[0046] On the third aspect, the present application proposes an electrical device (not shown in the figure), which includes a shell and the above-mentioned lithium-ion battery; the shell has a battery mounting slot; the lithium-ion battery is installed in the shell corresponding to the battery mounting slot.

[0047] It should be noted that the electrical equipment is a device that can convert the electrical energy of the above-mentioned battery into other forms of energy; for example, the electrical equipment can be but is not limited to lighting equipment such as flashlights and voice-controlled lights; for another example, the electrical equipment can also be but is not limited to timing devices such as electronic watches and electronic clocks.

[0048] Based on the electrical equipment in the embodiment of the present application, the above-mentioned lithium-ion battery can effectively reduce or even avoid lithium plating of the anode electrode 20 located in the inner circle, ensure the cycle life performance of the lithium-ion battery, and thus improve the service life of the electrical equipment.

[0049] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A winding core for improving head lithium deposition, comprising a cathode electrode, a diaphragm, and an anode electrode stacked and wound in sequence; characterized in that: The innermost circle of the anode electrode sheet is bent away from the winding core to form a folded portion, and the folded portion is in contact with the surrounding anode electrode sheet and / or the separator.

2. The winding core for improving lithium deposition on the head according to claim 1, characterized in that: The innermost circle of the anode electrode is bent from the starting end toward the direction away from the winding core to form the folded portion.

3. The winding core for improving lithium deposition on the head according to claim 2, characterized in that: The remaining portion of the innermost circle of the anode electrode is used to form a non-folded portion; the folded portion includes: A first folded portion, connected to the non-folded portion by a fold; The second folded portion is connected to the first folded portion at one end thereof which is bent away from the non-folded portion. The second folded portion and the non-folded portion are located on the same side of the first folded portion. The second folded portion abuts against the anode plate and / or diaphragm around it.

4. The winding core for improving lithium deposition on the head according to claim 3, characterized in that: The second folded portion has a curvature matched with the non-folded portion.

5. The winding core for improving lithium deposition on the head according to any one of claims 1 to 4, characterized in that: The folded portion includes a current collector and an active material layer disposed on a surface of the current collector.

6. The winding core for improving lithium deposition on the head according to any one of claims 1 to 4, characterized in that: The thickness of the folded portion is D, and D satisfies the condition: 0.05 mm ≤ D ≤ 0.15 mm.

7. The winding core for improving lithium deposition on the head according to any one of claims 1 to 4, characterized in that: The length of the folded portion is L, and L satisfies the condition: 0.5 mm ≤ L ≤ 5 mm.

8. The winding core for improving lithium deposition on the head according to any one of claims 1 to 4, characterized in that: The length of the folded portion is L, the radial cross-sectional circumference of the innermost circle of the anode pole piece is C, and L and C satisfy the conditional formula: L / C ≥ 1 / 3.

9. A lithium-ion battery, characterized in that: include: a housing having a receiving cavity; The winding core for improving lithium deposition on the head according to any one of claims 1 to 8, wherein the winding core is arranged in the accommodating cavity; and The electrolyte is poured into the accommodating cavity.

10. An electrical device, characterized in that: include: A housing having a battery mounting slot; and The lithium-ion battery according to claim 9, wherein the lithium-ion battery is mounted on the housing corresponding to the battery mounting slot.

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