New cover plate and lithium-ion battery
By machining spiral guide grooves on the inner wall of the electrolyte injection hole in the lithium-ion battery cover and setting elastic sheets under the injection molded parts, combined with a transparent battery casing, the problem of electrolyte overflow was solved, achieving precise electrolyte injection and preventing overflow, thus improving battery production yield and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 中汽新能(天津)电池科技有限公司
- Filing Date
- 2025-06-30
- Publication Date
- 2026-07-17
AI Technical Summary
In existing lithium-ion batteries, electrolyte is prone to overflow during the electrolyte filling process, resulting in cost waste and cell contamination. Furthermore, existing methods for measuring electrolyte filling volume are inaccurate, making it difficult to guarantee that the cell performance meets requirements.
A novel cover plate is designed, with spiral guide grooves machined on the inner wall of the injection hole and an elastic sheet with cross-shaped slits set below the injection molded part. Combined with a transparent battery shell, this achieves precise injection of electrolyte and prevents overflow.
By using spiral guide channels and elastic sheets, electrolyte overflow is limited, ensuring accurate electrolyte injection, avoiding waste and contamination, and improving battery production yield and reliability.
Smart Images
Figure CN224520160U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of lithium-ion battery technology, specifically relating to a novel cover plate and a lithium-ion battery. Background Technology
[0002] As the energy density of lithium-ion prismatic batteries increases, the compaction density of the positive and negative electrode sheets continues to rise, and users are demanding higher battery cycle life. Since the main function of the electrolyte inside a lithium-ion battery is to facilitate ion conduction between the positive and negative electrodes, the electrolyte injection volume needs to be increased simultaneously to ensure that the cell performance meets requirements.
[0003] Currently, the design of the liquid injection volume mainly relies on theoretical calculations, that is, calculating the liquid capacity based on the theoretical free space inside the casing. However, the porosity variations between the positive electrode, separator, and negative electrode often deviate from the calculations. From a design perspective, it is necessary to consider not only the cell's cycle performance but also the maximum liquid capacity of the casing.
[0004] Because the internal structure of aluminum-cased battery cells cannot be directly observed, current technologies typically rely on indirect measurements or destructive testing to accurately determine the injection volume. This can easily lead to excessive electrolyte, causing leakage after injection. This not only wastes resources but also contaminates the cells, resulting in defective products.
[0005] In addition, the edges of existing injection holes are smooth, making it easy for electrolyte to climb up and overflow through the hole walls; injection molded parts are generally leaky and cannot effectively prevent electrolyte from overflowing. Utility Model Content
[0006] The purpose of this invention is to provide a novel cover plate and lithium-ion battery to solve the problem of electrolyte overflow in the prior art.
[0007] To achieve the above objectives, the present invention provides the following technical solution: a novel cover plate, comprising a cover plate body, wherein the cover plate body is provided with an injection hole, and a spiral guide groove is machined on the inner wall of the protruding part of the injection hole extending beyond the lower plane of the cover plate body.
[0008] Preferably, the spiral guide groove has a groove width of 0.3-0.5 mm and a groove depth of 0.2-0.5 mm.
[0009] Preferably, a thin sheet is laminated on the injection molded part below the injection hole, and the thin sheet is provided with a cross-shaped slit. The cross-shaped slit opens automatically under the action of gravity during injection, and the thin sheet automatically springs back to close the hole when no electrolyte is injected.
[0010] Preferably, the protruding portion of the injection hole extends 2 mm beyond the plane of the cover plate.
[0011] Preferably, the elastic sheet is made of plastic material and is disposed at the bottom of the injection molded part, near one end of the core.
[0012] Preferably, the cover plate body is composed of an aluminum part and an injection-molded part. The injection hole includes an injection hole in the aluminum part of the cover plate and an injection hole in the injection-molded part. The injection hole in the aluminum part of the cover plate and the injection hole in the injection-molded part are aligned. The spiral guide groove is disposed inside the injection hole in the aluminum part of the cover plate. This utility model also discloses a lithium-ion battery including the novel cover plate. The battery casing is made of polyphenylene sulfide (PPS) material, and a transparent dye is added to the PPS material to make the battery casing transparent.
[0013] Preferably, the battery housing includes a housing opening, and the aluminum component is fixed to the housing opening of the battery housing by laser welding.
[0014] Preferably, the battery housing includes a housing opening, the liquid injection hole of the novel cover plate is aligned with the liquid injection channel of the housing, and the spiral guide groove on the inner wall of the liquid injection hole is connected to the liquid injection path inside the housing.
[0015] Preferably, the battery casing includes a casing opening, and a battery cell body is installed inside the battery casing. The electrode tabs of the battery cell body are welded and fixed to the electrode posts of the novel cover plate.
[0016] Preferably, the injection-molded part of the novel cover plate is fitted with the internal structure of the housing to form a sealed channel to prevent electrolyte leakage.
[0017] The beneficial effects of this utility model are:
[0018] The novel cover plate structure provided by this utility model has a spiral guide groove (groove width 0.3-0.5mm, groove depth 0.2-0.5mm) processed on the inner wall of the protruding part of the injection hole. The surface tension is used to limit the overflow of electrolyte and avoid the problem of electrolyte climbing and overflowing due to the smooth edge of the injection hole.
[0019] The novel cover plate provided by this utility model has an elastic sheet with a cross-shaped slit on the injection molded part below the injection hole. Under the action of gravity, the slit opens to inject liquid, and when there is no liquid, it rebounds to close the hole, effectively blocking the electrolyte overflow channel.
[0020] The novel cover plate provided by this utility model has a transparent structure made of polyphenylene sulfide (PPS) material with added transparent dyes for the battery casing. This allows for direct observation of the electrolyte level inside the cell, enabling precise determination of the electrolyte injection volume in the first and second injection processes. Combined with the sealing structure of the cover plate and the casing, the injection coefficient can be determined. This ensures that the electrolyte injection volume meets the cell performance requirements during mass production, while avoiding cost waste, cell contamination, and safety issues caused by electrolyte overflow, thereby improving battery production yield and reliability. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the cover plate in this utility model;
[0022] Figure 2 This is a front view of the battery cell in this utility model;
[0023] Figure 3 This is a schematic diagram of the unfolded battery cell and cover plate in this utility model;
[0024] Figure 4 This is a schematic diagram of the structure of the folding battery cell and cover plate in this utility model;
[0025] Figure 5 This is a schematic diagram of the housing after the battery cell is installed in the housing in this utility model;
[0026] Figure 6 This is a schematic diagram of the assembled lithium battery according to this utility model;
[0027] Figure 7 This is a side view of the cover plate in this utility model;
[0028] Figure 8 This is an enlarged view of the cover plate in this utility model;
[0029] Figure 9 This is an enlarged view of the spiral guide groove in this utility model;
[0030] Explanation of reference numerals in the attached drawings: 1. Cell cover plate; 2. Cell; 3. Unfolded cell; 4. Folded cell; 5. Aluminum shell; 5-1. Aluminum shell opening; 6. Overall cell; 7. Cover plate body; 7-1. Cover plate aluminum part; 7-2. Cover plate injection molded part; 7-3. Injection hole of injection molded part; 7-3-1. Elastic sheet; 7-4. Injection hole of cover plate aluminum part; 8. Spiral guide groove. Detailed Implementation
[0031] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings and preferred embodiments.
[0032] like Figure 1 and Figure 2 As shown, a novel cover plate is composed of an aluminum cover plate part 7-1 and an injection-molded cover plate part 7-2. The aluminum cover plate part 7-1 is provided with an aluminum cover plate part injection hole 7-4, and the injection-molded cover plate part 7-2 is provided with a corresponding injection-molded part injection hole 7-3, and the two are aligned to form a through injection channel.
[0033] Traditional aluminum cover plates have smooth internal injection holes, while injection-molded parts have leakage holes. Their primary function is to inject electrolyte into the battery cell. Simultaneously, the injection hole also serves to secure the sealing nails, causing it to protrude 2mm beyond the cover plate's surface. When the electrolyte level reaches the bottom of the protruding injection hole, battery cell movement can cause electrolyte overflow. To address this, this device incorporates a spiral guide groove 8 machined into the inner wall of the protruding portion of the aluminum cover plate's injection hole 7-4 beyond the cover plate body 7. The groove is 0.3-0.5mm wide and 0.2-0.5mm deep. This spiral guide groove 8 utilizes surface tension to limit electrolyte overflow.
[0034] The cover plate below the injection hole 7-3 of the injection molded part 7-2 is laminated with an elastic sheet 7-3-1. The elastic sheet 7-3-1 has a cross-shaped slit, preferably 2mm*2mm in size. Under the action of gravity during injection, the cross-shaped slit automatically opens, allowing electrolyte to enter the battery cell; when no electrolyte is injected, the elastic sheet 7-3-1 automatically rebounds to close the hole, preventing electrolyte from overflowing.
[0035] The elastic sheet 7-3-1 is made of plastic material and fits tightly against the inner wall of the injection hole 7-3 in the injection molded part. Because an opening with automatically rebounding plastic material is added to the injection molded part below the injection hole, the opening allows electrolyte to be injected into the battery cell under gravity. When gravity is absent, the plastic rebounds, sealing the injection port and preventing electrolyte from overflowing. This design of the injection hole ensures that the channel for electrolyte overflow is blocked while still having a fixed sealing nail, thus achieving the purpose of preventing leakage.
[0036] This utility model also discloses a lithium-ion battery. The battery casing 5 is made of polyphenylene sulfide (PPS) material, to which a transparent dye is added, making the casing 5 a transparent structure so as to observe the internal electrolyte level. The plastic material of the casing is only used for observing the electrolyte level and wetting effect, and is not used for welding to the casing to manufacture the battery. The casing 5 meets the performance requirements of high temperature resistance and corrosion resistance.
[0037] like Figure 1-6 As shown, the lithium-ion battery manufacturing process is as follows: winding or stacking - welding - core assembly - encapsulation - casing - sealing - baking - first injection - standing - negative pressure formation - second injection.
[0038] like Figure 1 As shown, the cell cover plate 1 includes a positive terminal 1-1 and a negative terminal 1-2. Figure 2 As shown, cell 2 includes a positive electrode tab 2-1 and a negative electrode tab 2-2. Cell cover plate 1 and cell 2 are welded together by the positive electrode tab 2-1 and the positive electrode post 1-1 of the cover plate, and by the negative electrode tab 2-2 and the negative electrode post 1-2 of the cover plate, forming positive electrode solder mark 3-1 and negative electrode solder mark 3-2 respectively. Figure 3As shown, this forms the unfolded battery cell 3, which is then combined and flipped together, as shown. Figure 4 As shown, a folded battery cell 4 is formed and secured using tape 4-1. The folded battery cell 4 is then inserted into the aluminum casing 5, as shown. Figure 5 As shown, the cover plate 1 and the aluminum shell opening 5-1 are then laser welded to form the overall battery cell 6, as shown. Figure 6 As shown.
[0039] like Figure 7 As shown: During use, the electrolyte is injected into the battery cell through the injection hole 7-4 in the aluminum cover plate and the injection hole 7-3 in the injection molded part. 85% electrolyte is injected initially, followed by a 24-hour rest period, or a second 15% electrolyte injection after negative pressure formation.
[0040] An elastic sheet 7-3-1 is attached to the electrolyte injection hole 7-3 of the filling component. The elastic sheet 7-3-1 has a cross-shaped slit. This slit automatically opens under the weight of the electrolyte injection, allowing electrolyte to enter the cell. When no electrolyte is injected, the elastic sheet 7-3-1 slowly and automatically springs back and closes. This prevents electrolyte from overflowing from the cell, saving electrolyte costs and ensuring the consistency of electrolyte volume within the battery.
[0041] Test observation and test locations: Injection process 1 and injection process 2;
[0042] In a single injection process, electrolyte is injected and the injection effect and electrolyte level in the casing are observed to determine the maximum amount of electrolyte that can be injected at one time to ensure that the cell does not overflow, thus determining the most suitable amount of electrolyte to be injected at one time.
[0043] The electrolyte is injected in the second injection process, and the injection effect and electrolyte level in the shell are observed to determine the appropriate amount of electrolyte to ensure that the cell does not overflow.
[0044] It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.
Claims
1. A novel cover plate characterized in that, Includes a cover plate body, on which a liquid injection hole is provided, and a spiral guide groove is machined on the inner wall of the protruding part of the liquid injection hole that extends beyond the lower plane of the cover plate body; The spiral guide groove has a groove width of 0.3-0.5 mm and a groove depth of 0.2-0.5 mm.
2. The novel cover sheet according to claim 1, characterized in that: The protruding part of the injection hole extends 2mm beyond the plane of the cover plate.
3. The novel cover sheet according to claim 1, characterized in that: An elastic sheet is provided on the injection molded part below the injection hole. The elastic sheet has a cross-shaped slit. The cross-shaped slit opens automatically under the gravity of the injection. When no electrolyte is injected, the elastic sheet automatically rebounds and closes the hole.
4. The novel cover sheet according to claim 3, characterized in that: The elastic sheet is made of plastic material and is located at the bottom of the injection molded part, near one end of the core.
5. The novel cover sheet according to claim 1, characterized by: The cover plate body is composed of an aluminum part and an injection molded part. The injection hole includes an injection hole in the aluminum part of the cover plate and an injection hole in the injection molded part. The injection hole in the aluminum part of the cover plate and the injection hole in the injection molded part are aligned. The spiral guide groove is located inside the injection hole in the aluminum part of the cover plate.
6. A lithium-ion battery comprising the novel cover plate according to any one of claims 1 to 5, characterized in that The battery casing is a transparent polyphenylene sulfide casing.
7. The lithium-ion battery of claim 6, wherein: The battery housing includes a housing opening, and the aluminum component is fixed to the housing opening by laser welding.
8. The lithium-ion battery of claim 6, wherein: The battery housing includes a housing opening, the liquid injection hole of the novel cover plate is aligned with the liquid injection channel of the housing, and the spiral guide groove on the inner wall of the liquid injection hole is connected to the liquid injection path inside the housing.
9. The lithium-ion battery of claim 6, wherein: The battery casing includes a casing opening, and a battery cell body is installed inside the battery casing. The electrode tabs of the battery cell body are welded and fixed to the electrode posts of the novel cover plate. The injection-molded part of the novel cover plate fits into the internal structure of the housing to form a sealed channel that prevents electrolyte leakage.