Cover plate assembly and secondary battery

Abstract

The utility model relates to lithium battery technical field especially, more particularly to a cover plate subassembly and secondary battery, the cover plate subassembly provided by the utility model embodiment includes cover plate, third electrode, active lithium supplement substance and protective layer, third electrode sets up in the cover plate, including the lead-out part of cover plate outer surface and the connecting part of cover plate inner surface, active lithium supplement substance sets up in the inner surface of cover plate and with the connecting part electric nature connection of third electrode, the protective layer sets up in active lithium supplement substance surface for sealing active lithium supplement substance, the cover plate subassembly provided by the utility model embodiment can realize the protection and use of active lithium supplement substance under relatively simple production environment, guarantees lithium supplement effect simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a cover plate assembly and a secondary battery. Background Technology

[0002] Lithium-ion batteries inevitably experience irreversible capacity loss during the first charge-discharge cycle. This capacity loss mainly stems from the formation of the SEI film on the negative electrode surface and the irreversible capacity loss of the positive electrode material. To compensate for this capacity loss, a pre-lithiation process is typically employed, which involves introducing an additional lithium source into the battery to compensate for the irreversible capacity loss.

[0003] Existing pre-lithiation processes mainly include the following methods: one is to directly incorporate lithium source materials into the negative electrode slurry during the preparation of the negative electrode sheet; another is to add sacrificial lithium salts to the positive electrode; and yet another is to place metallic lithium sheets in the cell for use during the first charge and discharge process. However, these technical solutions all share a common problem: because metallic lithium and its alloy-based lithium replenishment materials are highly reactive with moisture and oxygen in the air, it is difficult to maintain their activity during battery assembly. To solve this problem, existing technologies typically require battery assembly operations to be carried out in a harsh inert atmosphere environment (such as a dry chamber with a dew point below -40°C), which greatly increases production costs and reduces production efficiency. Utility Model Content

[0004] This invention provides a cover plate assembly and a secondary battery. The cover plate assembly can protect and use active lithium-replenishing materials in a relatively simple production environment, while ensuring the lithium replenishment effect.

[0005] In a first aspect, the present invention provides a cover plate assembly, comprising: a cover plate; a third electrode disposed on the cover plate, including an outlet portion located on the outer surface of the cover plate and a connecting portion located on the inner surface of the cover plate; an active lithium replenishing material disposed on the inner surface of the cover plate and electrically connected to the connecting portion of the third electrode; and a protective layer disposed on the surface of the active lithium replenishing material for sealing the active lithium replenishing material.

[0006] In one possible implementation, the protective layer is a thin film made of a heat-sensitive material.

[0007] In one possible implementation, the heat-sensitive material melts or shrinks within a temperature range of 80-90°C.

[0008] In one possible implementation, the heat-sensitive material is EVA.

[0009] In one possible implementation, an insulating layer is also included, disposed between the cover plate and the active lithium replenishing material, for isolating the cover plate and the active lithium replenishing material.

[0010] In one possible implementation, the inner surface of the cover plate is provided with a receiving groove, and the active lithium replenishing material is disposed in the receiving groove.

[0011] In one possible implementation, the depth of the containment tank is greater than the thickness of the active lithium-replenishing material.

[0012] Secondly, this utility model embodiment also provides a secondary battery, including: a casing; a battery cell disposed within the casing, including a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode; the aforementioned cover plate assembly, the cover plate being sealed to the casing; and an electrolyte medium filling the casing.

[0013] In one possible implementation, the battery cell further includes: a first terminal block electrically connected to the positive electrode; a second terminal block electrically connected to the negative electrode; and a conductive component for selectively connecting the lead-out portion of the third electrode to either the first or the second terminal block.

[0014] In one possible implementation, the protective layer of the cover plate assembly melts or shrinks within a temperature range of 80°C to 90°C, so that the active lithium-replenishing material of the cover plate assembly comes into contact with the electrolyte medium.

[0015] This invention provides a cover plate assembly and a secondary battery. The cover plate assembly forms a modular lithium replenishment unit by placing an active lithium replenishing material on the inner surface of the cover plate and electrically connecting it to a third electrode. This design integrates the lithium replenishment function into the cover plate assembly, allowing the preparation of the lithium replenishment unit to be separated from cell manufacturing, facilitating production management. A protective layer is applied to the surface of the active lithium replenishing material for sealing, completely isolating it from the external environment. The active lithium replenishing material will not come into contact with moisture or oxygen in the air before battery assembly, thus maintaining its activity. This overcomes the stringent requirements of traditional processes for the production environment, allowing battery assembly to be carried out in ordinary cleanrooms (e.g., dew point above -20°C) instead of in dry rooms with dew points below -40°C. This significantly reduces the requirements for the production environment while ensuring the lithium replenishment effect. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a cross-sectional structural diagram of a cover plate assembly provided by this utility model.

[0018] Figure 2yes Figure 1 A magnified schematic diagram of the structure at point A.

[0019] Figure 3 This is a schematic diagram of the structure of a secondary battery provided by this utility model.

[0020] Figure 4 This is a top-down view of a secondary battery lithium replenishment operation provided by this utility model.

[0021] Figure label: 1. Cover plate; 11. Receiving tank; 2. Third electrode; 21. Lead-out part; 22. Connecting part; 3. Active lithium replenishing material; 4. Protective layer; 5. Insulating layer; 6. Housing; 7. Battery cell; 8. First terminal; 9. Second terminal; 10. Conductive component. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0023] The following is combined Figure 1-4 A cover plate assembly provided in this embodiment of the present invention includes a cover plate 1, a third electrode 2, an active lithium-replenishing material 3, and a protective layer 4, wherein: The cover plate 1 is used to seal the top opening of the battery casing 6.

[0024] The third electrode 2 is disposed on the cover plate 1, including an outlet portion 21 located on the outer surface of the cover plate 1 and a connecting portion 22 located on the inner surface of the cover plate 1.

[0025] The active lithium replenishing material 3 is disposed on the inner surface of the cover plate 1 and electrically connected to the connection part 22 of the third electrode 2.

[0026] The protective layer 4 is disposed on the surface of the active lithium replenishing substance 3 and is used to seal the active lithium replenishing substance 3.

[0027] In this embodiment of the invention, a modular lithium replenishment unit is formed by placing the active lithium replenishing material 3 on the inner surface of the cover plate 1 and electrically connecting it to the cover plate via the third electrode 2. This design integrates the lithium replenishment function onto the cover plate assembly, allowing the preparation of the lithium replenishment unit to be separated from the manufacturing of the battery cell 7, facilitating production management. A protective layer 4 is provided on the surface of the active lithium replenishing material 3 for sealing, completely isolating the active lithium replenishing material 3 from the external environment. The active lithium replenishing material 3 will not come into contact with moisture or oxygen in the air before battery assembly, thus maintaining its activity. This overcomes the stringent requirements of the production environment in traditional processes, allowing battery assembly to be carried out in ordinary cleanrooms (such as those with a dew point above -20°C) instead of operating in a dry room with a dew point below -40°C. This greatly reduces the requirements for the production environment while ensuring the lithium replenishment effect.

[0028] Specifically, since the active lithium-replenishing material 3 is disposed on the inner surface of the cover plate 1, it can directly contact the electrolyte during battery assembly without altering the internal structure of the traditional battery. Simultaneously, the protective layer 4 effectively isolates the active lithium-replenishing material 3 from the external environment before battery assembly, preventing it from reacting with moisture and oxygen in the air and becoming ineffective. Compared to the traditional method of adding lithium-replenishing agents during electrode fabrication, this design significantly reduces the humidity and dew point requirements of the production environment, thus reducing dependence on the production environment. For example, in traditional processes, the addition of lithium-replenishing agents needs to be carried out in a dry room with a dew point below -40°C. However, with this solution, because the active lithium-replenishing material 3 is sealed by the protective layer 4, assembly operations can be performed in a standard cleanroom (dew point above -20°C).

[0029] In some embodiments, the protective layer 4 is a thin film made of a heat-sensitive material.

[0030] In this embodiment of the invention, the protective layer 4 is designed as a thin film made of a thermosensitive material, enabling intelligent control of its removal. This design utilizes the baking process in battery manufacturing, eliminating the need for additional steps to remove the protective layer 4. Compared to mechanical removal or chemical dissolution, this thermosensitive film design is simpler and more reliable, and does not introduce additional contaminants. In practical applications, such as in the production of 18650 cylindrical batteries, a 20μm thick thermosensitive film can be selected. This film possesses good mechanical strength and sealing properties at room temperature, maintaining its integrity during battery assembly and handling. Simultaneously, the protective layer 4 can be automatically removed during the baking stage, allowing the active lithium-replenishing material 3 to fully immerse in the electrolyte during subsequent electrolyte injection. This enables the third electrode 2 and the positive or negative electrode post of the cell 7 to undergo electrochemical pre-lithiation via a controlled circuit current, thereby achieving lithium replenishment.

[0031] Furthermore, heat-sensitive materials melt or shrink within a temperature range of 80℃-90℃.

[0032] In this embodiment of the invention, the thermosensitive material is specifically defined to melt or shrink within a temperature range of 80℃-90℃. This temperature range is highly compatible with the battery manufacturing process. In actual production, the baking temperature of the battery is usually controlled at 85±5℃. This temperature is sufficient to remove moisture from the battery without adversely affecting other materials inside the battery. Setting the melting or shrinkage temperature of the protective layer 4 within this range ensures that the protective layer 4 naturally detaches during the baking process. For example, in the production of square aluminum-cased batteries, when the oven temperature rises to 85℃, the thermosensitive material will melt or shrink within 3-5 minutes. The entire process is automatic and requires no manual intervention.

[0033] In some embodiments, the heat-sensitive material is EVA.

[0034] In this embodiment of the invention, the selection of EVA material as the heat-sensitive material offers several advantages. First, EVA material possesses excellent sealing properties, effectively blocking moisture and oxygen at room temperature. Second, EVA material exhibits good compatibility with the active lithium-replenishing substance 3, preventing chemical reactions. Third, after melting, EVA material does not form particulate residues but rather a uniform thin layer, ensuring unimpeded electrolyte wetting. In practical applications, such as during the production of pouch batteries, the protective layer 4 of EVA material, after melting, forms a transparent thin layer less than 1 μm thick. This thin layer does not affect the contact between the electrolyte and the active lithium-replenishing substance 3, nor does it interfere with the normal operation of the battery.

[0035] In some embodiments, an insulating layer 5 is also included, which is disposed between the cover plate 1 and the active lithium replenishing substance 3 to isolate the cover plate 1 and the active lithium replenishing substance 3.

[0036] In this embodiment of the invention, by providing an insulating layer 5 between the cover plate 1 and the active lithium-replenishing material 3, a short circuit between the active lithium-replenishing material 3 and the cover plate 1 is effectively prevented. This design is particularly suitable for cases where the cover plate 1 is metal, because the metal cover plate 1 is conductive, and if the active lithium-replenishing material 3 is in direct contact with the cover plate 1, an unintended current path may be formed. In practical applications, various forms such as ceramic coatings, alumina coatings, or polymer films can be selected as the insulating layer 5. For example, using a 0.2mm thick polypropylene film as the insulating layer 5 can withstand a breakdown voltage of over 200V and also has good electrolyte resistance. This insulating layer 5 not only improves battery safety but also increases design flexibility, allowing for more free placement of the active lithium-replenishing material 3.

[0037] In some embodiments, the inner surface of the cover plate 1 is provided with a receiving groove 11, and the active lithium replenishing material 3 is disposed in the receiving groove 11.

[0038] In this embodiment of the invention, an accommodating groove 11 is provided on the inner surface of the cover plate 1 to accommodate the active lithium-replenishing material 3. This structural design has several advantages. First, the accommodating groove 11 can accurately position the active lithium-replenishing material 3, ensuring reliable contact between it and the connection portion 22 of the third electrode 2. Second, the accommodating groove 11 forms a relatively enclosed space, which is beneficial for the protective layer 4 to seal the active lithium-replenishing material 3. Third, the edge of the accommodating groove 11 can provide support and adhesive surface for the protective layer 4, improving the reliability of the seal. In practical applications, different shapes of accommodating grooves 11 can be selected according to the battery type. For example, an annular accommodating groove 11 can be used for cylindrical batteries; a rectangular accommodating groove 11 can be used for prismatic batteries. This flexible design can adapt to the needs of different types of batteries.

[0039] In some embodiments, the depth of the receiving groove 11 is greater than the thickness of the active lithium replenishing material 3.

[0040] In this embodiment of the invention, by limiting the depth of the receiving groove 11 to be greater than the thickness of the active lithium-replenishing material 3, this design ensures that the active lithium-replenishing material 3 is completely contained within the receiving groove 11 and will not accidentally come into contact with other battery components. For example, when the thickness of the active lithium-replenishing material 3 is 0.5 mm, the depth of the receiving groove 11 can be designed to be 0.8 mm, leaving a 0.3 mm space on the surface of the active lithium-replenishing material 3. This extra space can accommodate the protective layer 4 and provide a channel for electrolyte wetting after the protective layer 4 melts. In addition, this depth design can also prevent the active lithium-replenishing material 3 from being squeezed and deformed during battery assembly.

[0041] The cover plate assembly forms a modular lithium replenishment unit by placing the active lithium replenishing material 3 on the inner surface of the cover plate 1 and electrically connecting it to the cover plate 1 via a third electrode 2. This design integrates the lithium replenishment function onto the cover plate assembly, allowing the preparation of the lithium replenishment unit to be separated from the manufacturing of the battery cell 7, facilitating production management. A protective layer 4 is applied to the surface of the active lithium replenishing material 3 for sealing, completely isolating it from the external environment. The active lithium replenishing material 3 will not come into contact with moisture or oxygen in the air before battery assembly, thus maintaining its activity. This overcomes the stringent requirements of traditional processes for the production environment, allowing battery assembly to be carried out in ordinary cleanrooms (such as those with a dew point above -20°C) instead of operating in dry rooms with a dew point below -40°C. This significantly reduces the requirements for the production environment while ensuring the effectiveness of lithium replenishment.

[0042] This utility model embodiment also provides a secondary battery, including: a housing 6; a battery cell 7 disposed within the housing 6, including a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode; the aforementioned cover plate assembly, wherein the cover plate 1 is sealed to the housing 6; and an electrolyte medium filled within the housing 6.

[0043] In this embodiment of the invention, by applying the cover plate assembly to the secondary battery, a complete lithium-ion battery system is formed. The cover plate assembly can be inspected as an independent unit, improving product reliability. Secondly, the sealing connection between the cover plate 1 and the casing 6 is the same as that of a conventional battery, requiring no changes to the existing sealing process. Thirdly, the filling of the electrolyte medium can simultaneously achieve the wetting of the cell 7 and the activation of the active lithium-ion material 3. In practical applications, this design can be widely used in various types of secondary batteries. For example, in the production of power batteries, the appropriate amount of active lithium-ion material 3 can be configured according to the capacity of different battery models, achieving precise control of the lithium-ion replenishment amount.

[0044] In some embodiments, the battery cell 7 further includes: a first terminal 8 electrically connected to the positive electrode; a second terminal 9 electrically connected to the negative electrode; and a conductive component 10 for selectively connecting the lead-out portion 21 of the third electrode 2 to the first terminal 8 or the second terminal 9.

[0045] In this embodiment of the invention, the selectively connectable conductive component 10 enables flexible control of the lithium replenishment process. This design allows the lead-out portion 21 of the third electrode 2 to be connected to either the positive or negative electrode post as needed, thereby implementing different lithium replenishment strategies. For example, when pre-lithiation of the negative electrode is required, the third electrode 2 can be connected to the negative electrode post; when activation of the positive electrode is required, the third electrode 2 can be connected to the positive electrode post. This flexible connection method allows the lithium replenishment process to be optimized according to the specific state of the battery. In practical applications, the conductive component 10 can be a detachable metal clamp, which facilitates removal after lithium replenishment without affecting the subsequent use of the battery.

[0046] Specifically, the first electrode 8 is the positive electrode and the second electrode 9 is the negative electrode. When replenishing lithium, the third electrode 2 is electrically connected to the first electrode 8 or the second electrode 9 through the conductive component 10. Then, the lithium is replenished to the first electrode 8 or the second electrode 9 by controlling the current of the control circuit. After the lithium replenishment is completed, the conductive component 10 is removed, and the first electrode 8 and the second electrode 9 are fully replenished by the current flow of the secondary battery during use.

[0047] In some embodiments, the protective layer 4 of the cover plate assembly melts or shrinks within a temperature range of 80-90°C to allow the active lithium-replenishing material 3 of the cover plate assembly to come into contact with the electrolyte medium.

[0048] This embodiment of the invention specifically describes the working state of the active lithium-replenishing material 3 in contact with the electrolyte medium. This process is automatically achieved after the protective layer 4 melts or shrinks. The temperature range of 80-90℃ not only ensures the reliable detachment of the protective layer 4 but also promotes the wetting of the active lithium-replenishing material 3 by the electrolyte. In practical applications, this temperature range is highly compatible with the battery baking process, allowing the two processes of protective layer 4 detachment and electrolyte wetting to be completed automatically during baking. For example, in the production of pouch batteries, when the baking temperature reaches 85℃, the protective layer 4 will melt within minutes, and the subsequently injected electrolyte can quickly wet the exposed surface of the active lithium-replenishing material 3. The entire process is automatic, simple, and reliable.

[0049] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A cover plate assembly, characterized in that, include: Cover plate (1); The third electrode (2) is disposed on the cover plate (1) and includes an outlet (21) located on the outer surface of the cover plate (1) and a connecting part (22) located on the inner surface of the cover plate (1). An active lithium-replenishing material (3) is disposed on the inner surface of the cover plate (1) and electrically connected to the connection part (22) of the third electrode (2); A protective layer (4) is disposed on the surface of the active lithium-replenishing material (3) for sealing the active lithium-replenishing material (3).

2. The cover plate assembly as claimed in claim 1, characterized in that, The protective layer (4) is a thin film made of a thermosensitive material.

3. The cover plate assembly as claimed in claim 2, characterized in that, The heat-sensitive material melts or shrinks within a temperature range of 80-90°C.

4. The cover plate assembly as claimed in claim 2, characterized in that, The heat-sensitive material is EVA.

5. The cover plate assembly as claimed in claim 1, characterized in that, It also includes an insulating layer (5) disposed between the cover plate (1) and the active lithium replenishing substance (3) for isolating the cover plate (1) and the active lithium replenishing substance (3).

6. The cover plate assembly as described in any one of claims 1-5, characterized in that, The inner surface of the cover plate (1) is provided with a receiving groove (11), and the active lithium supplement material (3) is disposed in the receiving groove (11).

7. The cover plate assembly as claimed in claim 6, characterized in that, The depth of the receiving groove (11) is greater than the thickness of the active lithium supplement material (3).

8. A secondary battery, characterized in that, include: Casing (6); The battery cell (7) is disposed in the housing (6) and includes a positive electrode plate, a negative electrode plate and a separator disposed between the positive electrode plate and the negative electrode plate; The cover plate assembly as claimed in any one of claims 1-7, wherein the cover plate (1) of the cover plate assembly is sealingly connected to the housing (6); and An electrolyte medium is filled inside the shell (6).

9. The secondary battery as described in claim 8, characterized in that, The battery cell (7) also includes: The first electrode post (8) is electrically connected to the positive electrode plate; The second electrode post (9) is electrically connected to the negative electrode plate; and A conductive component (10) is used to selectively connect the lead-out portion (21) of the third electrode (2) to the first electrode post (8) or the second electrode post (9).

10. The secondary battery as described in claim 8, characterized in that, The protective layer (4) of the cover plate assembly melts or shrinks within a temperature range of 80°C-90°C, so that the active lithium-supplementing material (3) of the cover plate assembly comes into contact with the electrolyte medium.

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