Lithium ion battery, battery pack and electric device

Abstract

The utility model relates to a lithium ion battery, a battery pack and an electric device. The lithium ion battery comprises a shell, a battery cell and a supplementary lithium source, the shell is a conductive shell, and the battery cell is accommodated in the shell; the inner wall of the shell is at least divided into a first area and a second area, the supplementary lithium source covers the first area, and the shell is electrically connected with the negative pole piece of the battery cell in the second area; and the thickness of the supplemented lithium source is 2-6 [mu] m. A supplementary lithium source in the lithium ion battery is covered in a first area, a shell is electrically connected with a negative pole piece of a battery cell in a second area, the shell serves as a negative pole to be electrified, after liquid is injected into the battery cell, the supplementary lithium source and the inner wall of the shell form an electronic path, electrolyte provides an ion path, and in the formation process, the supplementary lithium source can compensate active lithium consumed due to SEI generation, so that the lithium ion battery is formed. Therefore, the first-circle coulombic efficiency is improved, and the cycle performance of the battery cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to a lithium-ion battery, a battery pack and an electrical device. Background Art

[0002] With the continuous increase in energy demand, the search for new energy storage devices has become a hot topic in the field of new energy. Lithium-ion batteries (LIBs) are currently the battery system with the best comprehensive performance, with high specific energy, high cycle life, small size, light weight, no memory effect, no pollution, etc., and have rapidly developed into a new generation of energy storage power sources, used for power support in information technology, electric and hybrid vehicles, aerospace and other fields. During the formation process of lithium-ion batteries, due to certain side reactions between lithium salts and electrolytes, a solid electrolyte interface (SEI) film will be generated on the negative electrode side of the lithium battery, which will consume a large amount of active lithium, resulting in low first-cycle coulomb efficiency and reduced capacity.

[0003] In the current lithium-ion battery system design, lithium replenishment technology for lithium-ion batteries is an important means to improve battery energy density. However, traditional lithium replenishment technology has more or less certain technical defects, and the actual lithium replenishment effect is not good. The lithium replenishment technology of lithium-ion batteries still needs to be improved.

[0004] For example, a secondary battery is provided in the patent with announcement number CN215008337U, including a battery cell, a lithium supplement source and a battery shell; wherein the lithium supplement source is arranged at at least one end of the battery cell. The lithium supplement source is any one of a metal lithium sheet, a metal sheet containing a metal lithium coating, and an insulating sheet containing a metal lithium coating. When the lithium supplement source is packaged together with the battery cell, an electronic insulator is used to disconnect the lithium supplement source from the battery cell to avoid direct electrical connection between the two, and then the lithium supplement source is led out by an external conductor, and the lithium supplement source is connected to the negative terminal of the battery cell through the external conductor. In this way, when the external source is turned on, the lithium supplement source loses electrons, and the electrons are transferred to the negative terminal via the external conductor, and the lithium in the lithium supplement source becomes lithium ions due to the loss of electrons, and enters the battery cell through the electronic insulator to achieve the effect of lithium supplement, thereby improving the first-cycle coulomb efficiency. However, the lithium replenishing source arranged on the end face of the battery cell in the above scheme is in sheet form and has a large thickness, which increases the internal space of the battery cell and increases the volume of the battery cell, which is not conducive to assembly. In addition, lithium is active, and the thicker the lithium sheet, the more severe the oxidation, which easily makes the surface of the lithium sheet lose its activity, resulting in poor lithium replenishment effect. Utility Model Content

[0005] Based on this, the present application provides a lithium-ion battery, a battery pack and an electrical device that have little impact on battery assembly and can improve the lithium replenishment effect.

[0006] In a first aspect, the present application provides a lithium-ion battery, comprising a housing, a battery cell and a supplementary lithium source, wherein the housing is a conductive housing, and the battery cell is accommodated inside the housing;

[0007] The inner wall of the shell is divided into at least a first area and a second area, the supplementary lithium source is covered in the first area, and the shell is electrically connected to the negative electrode sheet of the battery cell in the second area;

[0008] The thickness of the supplementary lithium source is 2 μm to 6 μm.

[0009] In some of these embodiments, the supplemental lithium source is a layer of lithium powder.

[0010] In some embodiments, the housing is a steel shell.

[0011] In some embodiments, the shell is a square shell or a cylindrical shell.

[0012] In some embodiments, the shell is a cylindrical shell, the inner wall of the cylindrical shell includes an inner side wall and an inner bottom wall arranged at the bottom of the inner side wall, the inner side wall is the first area of ​​the shell, the inner bottom wall is the second area of ​​the shell, the supplementary lithium source is covered on the inner side wall, and the inner bottom wall of the shell is electrically connected to the negative electrode sheet of the battery cell;

[0013] The top of the inner side wall is provided with an opening, and the lithium-ion battery further comprises a cover cap, which covers the opening.

[0014] In some embodiments, the battery cell further includes a positive electrode sheet and a separator, and the positive electrode sheet and the negative electrode sheet are separated by the separator.

[0015] In some embodiments, the positive electrode plate includes a positive electrode current collector covered with a positive electrode powder coating, and the positive electrode current collector is electrically connected to the cap through a positive electrode tab;

[0016] The negative electrode plate includes a negative electrode current collector covered with a negative electrode powder coating, and the negative electrode current collector is connected to the inner bottom wall of the shell through a negative electrode tab.

[0017] In some embodiments, the battery cell is a wound battery cell or a stacked battery cell.

[0018] In a second aspect, the present application provides a battery pack, comprising a lithium-ion battery as described in any embodiment of the first aspect above.

[0019] In a third aspect, the present application provides an electrical device, comprising a battery pack as described in any embodiment of the second aspect above.

[0020] The present application provides a lithium-ion battery, which divides the inner wall of the conductive shell into at least a first area and a second area, wherein the supplementary lithium source is covered in the first area, and the shell is electrically connected to the negative electrode of the battery cell in the second area, and the shell acts as a negative electrode with charge. After the battery cell is filled with liquid, the supplementary lithium source forms an electron path with the inner wall of the shell, and the electrolyte provides an ion path. During the formation process, the supplementary lithium source will compensate for the active lithium consumed by SEI generation, thereby improving the first-cycle coulomb efficiency and improving the cycle performance of the battery cell. Moreover, the supplementary lithium source is located on the inner wall of the shell, and the thickness is thin, which will not increase the internal space of the battery cell, has little effect on the assembly of the lithium-ion battery, and can effectively overcome the problem of easy deactivation of thick and heavy lithium sheets, ensuring the lithium supplement effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a lithium-ion battery in some embodiments.

[0022] Figure 2 Schematic diagram of the cross-sectional structure of lithium ions in some embodiments.

[0023] Description of reference numerals:

[0024] 1: lithium-ion battery; 10: shell; 20: battery cell; 210: negative electrode plate; 220: positive electrode plate; 230: diaphragm; 30: replenishing lithium source. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0026] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0028] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0030] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] In addition, the drawings are not drawn in a 1:1 ratio, and the relative sizes of the elements are drawn in the drawings only as examples to facilitate understanding of the present application, but are not necessarily drawn in true proportion. The proportions in the drawings do not constitute a limitation to the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] First, as Figure 1and Figure 2 As shown, the present application provides a lithium-ion battery 1, comprising a housing 10, a battery cell 20 and a supplementary lithium source 30, wherein the housing 10 is a conductive housing, and the battery cell 20 is accommodated inside the housing 10;

[0034] The inner wall of the shell 10 is divided into at least a first area and a second area. The supplementary lithium source 30 is covered in the first area, and the shell 10 is electrically connected to the negative electrode sheet 210 of the battery cell 20 in the second area.

[0035] The present application provides a lithium-ion battery 1, which divides the inner wall of the conductive shell 10 into at least a first area and a second area, wherein the supplementary lithium source 30 is covered in the first area, and the shell 10 is electrically connected to the negative electrode plate 210 of the battery cell 20 in the second area, and the shell 10 acts as a negative electrode with charge. After the battery cell 20 is injected with liquid, the supplementary lithium source 30 forms an electron path with the inner wall of the shell 10, and the electrolyte provides an ion path. During the formation process, the supplementary lithium source 30 will compensate for the active lithium consumed by SEI generation, thereby improving the first-cycle coulomb efficiency and improving the cycle performance of the battery cell 20. The supplementary lithium source 30 is located on the inner wall of the shell 10, and has a thin thickness, which will not increase the internal space of the battery cell 20, and has little effect on the overall volume of the lithium-ion battery 1, is easy to assemble and produce, and can effectively overcome the problem of easy deactivation of thick and heavy lithium sheets, ensuring the lithium supplement effect. The design method of the supplementary lithium source 30 used in the lithium-ion battery 1 provided in the present application is simple and stable, and can effectively compensate for the active lithium consumed by SEI generation.

[0036] In some embodiments, the thickness of the supplementary lithium source 30 is 2μm~6μm. If the thickness of the supplementary lithium source 30 is too small, it may lead to insufficient lithium source and weak lithium supplementation effect. If the thickness of the supplementary lithium source 30 is too large, it will affect the expansion space of the battery cell 20, which will have an adverse effect on the electrical performance and safety of the battery, and even cause the bare battery cell 20 to be unable to enter the shell. Moreover, if the thickness of the supplementary lithium source 30 is too large, the more intense the surface oxidation, the easier it is to deactivate and affect the lithium supplementation effect. Therefore, within the above-mentioned suitable thickness range, the supplementary lithium source 30 can provide a better lithium supplementation effect, and has little effect on the electrical performance, safety, etc. of the battery. It can be understood that the thickness of the supplementary lithium source 30 can be, for example, but not limited to, 2μm, 3μm, 4μm, 5μm, 6μm, etc.

[0037] In some embodiments, the supplementary lithium source 30 is a lithium powder layer. Lithium powder has a high specific surface area. Using a lithium powder layer as the supplementary lithium source 30 can have better electrochemical activity. Moreover, the raw material mixing uniformity of the lithium powder layer is better, and a more uniform supplementary lithium source 30 can be formed on the first area inside the shell 10. Furthermore, compared with a sheet-like lithium source, a lithium powder layer is easier to cover on the second area of ​​the inner wall of the shell 10 through processes such as spraying and plating, and the combination of the supplementary lithium source 30 and the inner wall of the shell 10 is more stable and firm.

[0038] In some embodiments, the housing 10 is a steel housing, which has good electrical conductivity and can be used as the negative electrode of the battery for electrical conduction.

[0039] In the present application, the housing 10 may be in various shapes and sizes, such as square, cylindrical, hexagonal, etc. Specifically, the shape and size of the housing 10 may be adapted according to the specific shape and size of the battery cell 20. In some embodiments, the housing 10 is a square housing or a cylindrical housing.

[0040] In some embodiments, the shell 10 is a cylindrical shell, the inner wall of the cylindrical shell includes an inner side wall and an inner bottom wall arranged at the bottom of the inner side wall, the inner side wall is the first area of ​​the shell 10, the inner bottom wall is the second area of ​​the shell 10, the supplementary lithium source 30 is covered on the inner side wall, and the inner bottom wall of the shell 10 is electrically connected to the negative electrode sheet 210 of the battery cell 20; the top of the inner side wall is provided with an opening, and the lithium ion battery 1 also includes a cap, and the cap covers the opening. An opening is provided at the top of the shell 10, and a cap matching the shell 10 is provided on the opening to isolate the internal environment of the lithium ion battery 1 from the external environment.

[0041] In some embodiments, the battery cell 20 further includes a positive electrode sheet 220 and a separator 230, and the positive electrode sheet 220 and the negative electrode sheet 210 are separated by the separator 230. The separator 230 can isolate the positive electrode and the negative electrode, and prevent the electrons in the battery from passing freely to avoid a short circuit of the battery, but can allow the ions in the electrolyte to pass freely between the positive and negative electrodes to ensure the normal operation of the battery. The material of the separator 230 can be, for example, but not limited to, a polyethylene (PE) separator, a polypropylene (PP) separator, or a composite separator composed of polyethylene and polypropylene.

[0042] In some embodiments, the positive electrode plate 220 includes a positive electrode current collector covered with a positive electrode powder coating, and the positive electrode current collector is electrically connected to the cap through the positive electrode tab; the negative electrode plate 210 includes a negative electrode current collector covered with a negative electrode powder coating, and the negative electrode current collector is connected to the inner bottom wall of the shell 10 through the negative electrode tab. The cap can act as a positive electrode and be electrically connected to the positive electrode tab of the battery, the shell 10 acts as a negative electrode of the battery, the negative electrode tab is electrically connected to the inner bottom wall of the shell 10, and the cap and the shell 10 are connected to the external circuit to form a loop. The negative electrode tab is connected to the inner bottom wall of the shell 10, and the positive electrode tab is connected to the cap located at the top of the shell 10. The battery structure design is more scientific, avoids the short circuit problem caused by the contact between the positive and negative electrodes, and is safer.

[0043] It can be understood that the material of the positive electrode current collector may be, for example, but not limited to, copper foil.

[0044] It can be understood that the material of the positive electrode powder coating includes positive electrode active material, conductive agent, adhesive, etc. Among them, the positive electrode active material can include, but is not limited to, lithium cobalt oxide, lithium iron phosphate, ternary material, etc.

[0045] It can be understood that the material of the negative electrode current collector may be, for example but not limited to, aluminum foil.

[0046] It can be understood that the material of the negative electrode powder coating includes negative electrode active material, conductive agent, binder, etc. Among them, the negative electrode active material can include, but is not limited to, graphite, silicon oxide, silicon carbon, etc.

[0047] It can be understood that the battery cell 20 can be, for example but not limited to, a wound battery cell 20 or a laminated battery cell 20 .

[0048] It is understandable that the lithium-ion battery 1 may also include a gasket, a safety valve and other conventional structures of a battery.

[0049] In a second aspect, the present application provides a battery pack, comprising a lithium-ion battery 1 as in any embodiment of the first aspect described above.

[0050] In a third aspect, the present application provides an electric device, including a battery pack as in any embodiment of the second aspect. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0051] The following are specific embodiments.

[0052] Example 1

[0053] A lithium-ion battery 1 comprises a cylindrical steel shell 10, a winding core and a lithium powder layer, wherein the winding core is accommodated inside the shell 10.

[0054] The inner wall of the shell includes an inner side wall and an inner bottom wall arranged at the bottom of the inner side wall. The inner side wall is the first area of ​​the shell, and the inner bottom wall is the second area of ​​the shell. The lithium powder layer covers the inner side wall, and the thickness of the lithium powder layer is 5μm.

[0055] The top of the inner wall is provided with an opening, and the lithium-ion battery 1 further comprises a cover cap, which covers the opening.

[0056] The winding core includes a positive electrode sheet 220 , a negative electrode sheet 210 and a separator 230 . The positive electrode sheet 220 and the negative electrode sheet 210 are separated by the separator 230 . The separator 230 is made of polypropylene.

[0057] The positive electrode sheet 220 includes a positive electrode current collector covered with a positive electrode powder coating, and the positive electrode current collector is electrically connected to the cap through the positive electrode tab. The material of the positive electrode current collector is copper foil. The material of the positive electrode powder coating includes a positive electrode active material, a conductive agent, and an adhesive, wherein the positive electrode active material is lithium cobalt oxide.

[0058] The negative electrode sheet 210 includes a negative electrode current collector covered with a negative electrode powder coating, and the negative electrode current collector is connected to the inner bottom wall of the shell 10 through a negative electrode tab. The material of the negative electrode current collector is aluminum foil. The material of the negative electrode powder coating includes a negative electrode active material, a conductive agent, and a binder. Among them, the negative electrode active material is graphite.

[0059] The core is shelled, spot welded, baked, injected, capped, and formed to test the cycle performance of the battery. The test shows that the lithium-ion battery 1 effectively improves the first-cycle coulomb efficiency and the cycle performance of the battery cell.

[0060] Comparative Example 1

[0061] It is substantially the same as Example 1, except that the inner wall of the steel shell is not covered with a lithium powder layer.

[0062] After testing, the above lithium-ion battery 1 failed to effectively improve the first-cycle coulomb efficiency and the cycle performance of the battery cell.

[0063] Comparative Example 2

[0064] It is substantially the same as Example 1, except that the thickness of the lithium powder layer covering the inner wall is 20 μm.

[0065] Since the lithium powder layer is too thick, the internal space of the shell becomes significantly smaller, and the internal space is not enough to put the bare battery cell into the shell.

[0066] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the utility model patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the attached claims described in the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A lithium ion battery, characterized in that: It includes a shell, a battery cell and a supplementary lithium source, wherein the shell is a conductive shell, and the battery cell is accommodated inside the shell; The inner wall of the shell is divided into at least a first area and a second area, the supplementary lithium source is covered in the first area, and the shell is electrically connected to the negative electrode sheet of the battery cell in the second area; The thickness of the supplementary lithium source is 2 μm to 6 μm.

2. The lithium-ion battery according to claim 1, characterized in that The supplementary lithium source is a lithium powder layer.

3. The lithium-ion battery according to claim 1, characterized in that The shell is a steel shell.

4. The lithium ion battery according to any one of claims 1 to 3, characterized in that The shell is a square shell or a cylindrical shell.

5. The lithium-ion battery according to claim 4, characterized in that: The shell is a cylindrical shell, the inner wall of the cylindrical shell includes an inner side wall and an inner bottom wall arranged at the bottom of the inner side wall, the inner side wall is the first area of ​​the shell, the inner bottom wall is the second area of ​​the shell, the supplementary lithium source is covered on the inner side wall, and the inner bottom wall of the shell is electrically connected to the negative electrode sheet of the battery cell; The top of the inner wall is provided with an opening, and the lithium-ion battery further comprises a cover cap, which covers the opening.

6. The lithium-ion battery according to claim 5, characterized in that: The battery cell further comprises a positive electrode sheet and a separator, wherein the positive electrode sheet and the negative electrode sheet are separated by the separator.

7. The lithium-ion battery according to claim 6, characterized in that: The positive electrode plate comprises a positive electrode current collector covered with a positive electrode powder coating, and the positive electrode current collector is electrically connected to the cap through a positive electrode tab; The negative electrode plate includes a negative electrode current collector covered with a negative electrode powder coating, and the negative electrode current collector is connected to the inner bottom wall of the shell through a negative electrode tab.

8. The lithium ion battery according to any one of claims 1 to 3 and 5 to 7, characterized in that: The battery core is a wound battery core or a laminated battery core.

9. A battery pack, characterized in that: Comprising a lithium ion battery as described in any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising the battery pack as claimed in claim 9.

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