Hollow elastic core rod and battery cell comprising same
By using a hollow elastic core and built-in electrolyte design, the deformation problem caused by electrode expansion and contraction during lithium battery cycling is solved, achieving battery stability and extended lifespan, and providing flame retardant and heat-resistant properties.
Patent Information
- Application Number
- CN202422224366.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-09-11
AI Technical Summary
Existing lithium batteries suffer from electrode embrittlement, material loss, and breakage due to deformation and increased internal pressure caused by electrode expansion and contraction during cycling. This is especially true for cylindrical wound batteries, where the internal compression deformation of the electrode assembly is severe, affecting battery life and safety.
It adopts a hollow elastic core rod, and utilizes elastic materials and built-in bagged electrolyte to relieve pressure through elastic deformation and release electrolyte when necessary to replenish the consumed electrolyte and improve battery cycle life.
It effectively supports the cell structure, alleviates pressure deformation, prevents collapse, extends battery cycle life, and improves the battery's flame retardancy and heat resistance.
Smart Images
Figure CN223625023U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to a hollow elastic core rod and a battery cell containing the hollow elastic core rod. Background Technology
[0002] A cylindrical battery consists of a cell formed by winding positive and negative electrode separators, positive and negative electrode covers, a casing, and electrolyte. The overall shape is cylindrical, and the casing can be made of aluminum or steel. The core rod is a central pin used to start winding the positive and negative electrodes and separators. The separator is usually attached to the surface of the core rod by tape or hot melt adhesive to begin winding. The core rod is used to support the cell. Currently, cells are usually wound using core rods or central pins, but winding without core rods is also possible.
[0003] As lithium-ion batteries cycle through charge and discharge, the positive and negative electrode sheets are constantly in a state of expansion and contraction (mainly due to changes in the thickness of the negative electrode sheet during lithium insertion / depletion during charge and discharge). Furthermore, with the increase in the number of lithium battery cycles, factors such as electrolyte consumption, intensified side reactions, and increased internal pressure cause the electrode sheets to become brittle, shed material, or even break. This is especially true for cylindrical wound batteries, where the presence of a central hole in the electrode assembly causes the electrode sheets to be squeezed inwards during battery cycles. As the cycles intensify, the internal compression and deformation of the electrode assembly leads to the breakage of the internal lithium-plated electrode sheets. In severe cases, this can result in a significant drop in battery cycle life and even safety hazards.
[0004] To address the issue of reduced cycle life in cylindrical batteries due to deformation during later cycles, battery manufacturers typically insert a core rod into the center hole. Inserting the core rod reduces deformation caused by expansion and inward compression, thereby minimizing internal side reactions such as lithium plating, gas generation, and cell breakage, ultimately extending battery life.
[0005] In the manufacturing process of battery cells, the core rod needs to be pre-wound with several turns of separator before inserting the positive and negative electrode plates. After winding, the winding needle is pulled out. After the center hole loses the support of the winding needle, the separator will shrink inward, causing the center hole to become smaller. Moreover, the separator is very thin and made of PP or PE material, so it will still produce a slight rebound. As a result, in the later stages of cycling, due to the expansion of the electrode plates, even if the cell is inserted, there is still space for the battery to expand inward. The cell cannot fully play its role in supporting the stability of the battery. With the increase of the number of cycles, the electrode plates are squeezed inward and deformed, resulting in side reactions such as lithium plating and gas production. As the chain reaction intensifies, it causes a significant decrease in battery performance, such as capacity loss. In the later stages of cycling, the inner cell layer of the battery will collapse and the cell will deform because there is no core rod support. Utility Model Content
[0006] The purpose of this invention is to provide a hollow elastic core rod and a battery cell containing the hollow elastic core rod; the hollow elastic core rod can, on the one hand, slowly release pressure to prevent collapse; on the other hand, it can improve cycle life by releasing the electrolyte stored in the hollow part.
[0007] Technical solution
[0008] Firstly, this application provides a hollow elastic core rod:
[0009] A hollow elastic core rod includes a hollow rod, sealing tape, and bagged electrolyte, wherein the bagged electrolyte is disposed inside the hollow rod; and the sealing tape is disposed at both ends of the hollow rod containing the bagged electrolyte.
[0010] Compared to ordinary alloy core rods and coreless designs, this application uses hollow elastic materials. Hollow elastic materials have better strength, elasticity, and toughness, which can effectively support the cells and batteries, and can also slowly absorb and release pressure to prevent the cells and batteries from collapsing. The hollow elastic materials are squeezed during battery expansion. After the packaging bag of the bagged electrolyte breaks, the electrolyte stored in the hollow part can be released for secondary injection to replenish the consumed electrolyte components, improve the cycle life of the battery, and inhibit cell failure.
[0011] Furthermore, the electrolyte in the bagged electrolyte is a high-concentration lithium salt electrolyte.
[0012] Furthermore, the hollow rod is made of an elastic material.
[0013] Furthermore, the elastic material is elastic hard rubber or fluororubber.
[0014] Made of elastic hard rubber, fluororubber and other materials, it is resistant to electrolyte corrosion, has a certain degree of support, and can deform under high pressure while maintaining good support.
[0015] Furthermore, the inner wall of the hollow rod is provided with protrusions that are used to break the packaging bag of the bagged electrolyte when the hollow rod is squeezed and deformed.
[0016] Furthermore, the diameter of the bagged electrolyte is smaller than the difference between the inner diameter of the hollow rod and the height of the protrusion.
[0017] Furthermore, the difference between the maximum length between the inner wall of the hollow rod and the protrusion and the diameter of the bagged electrolyte is in the range of 0-10 mm.
[0018] In this application, the difference between the maximum distance between the inner wall of the hollow rod and the protrusion and the diameter of the bagged electrolyte can be set according to the degree of deformation of the elastic rod and the estimated time point for secondary electrolyte replenishment.
[0019] Furthermore, the sealing tape is made of plastic; the packaging bag for the electrolyte is also made of plastic.
[0020] Furthermore, the packaging bag for the electrolyte is made of PE or PP; the sealing tape is made of PE or PP.
[0021] Furthermore, the bagged electrolyte can be the same electrolyte as the battery or a specially designed electrolyte.
[0022] Furthermore, the specially designed electrolyte is an electrolyte containing flame retardants or heat resistant agents.
[0023] The sealing tape at both ends of the hollow rod can be made of ordinary PE, PP or other materials. It serves to seal both ends of the hollow rod. The diameter of the sealing tape must be large enough to completely cover the hollow holes at both ends of the hollow rod.
[0024] For bagged electrolyte, the packaging bag can be made of electrolyte-resistant plastics such as PE or PP. The diameter of the bagged electrolyte should be slightly smaller than the difference between the inner diameter of the hollow rod and the height of the protrusion to facilitate the placement of the bagged electrolyte inside the hollow rod. The packaging bag should be thin enough to be punctured by the protrusion inside the core rod when the hollow rod deforms. The internal electrolyte can be the same type as that used in the battery, with specially designed electrolytes or other functional liquids such as flame retardants used to replenish the consumed electrolyte in the later stages of the cycle to improve cycle performance.
[0025] Secondly, this application provides a method for constructing a battery cell including the elastic core rod of this application:
[0026] A method for preparing an electric cell comprising the elastic core rod of this application may be selected from either method one or method two:
[0027] Method 1:
[0028] The bagged electrolyte is placed in the internal cavity of the hollow rod, and then the two ends of the hollow rod are sealed with sealing tape to obtain a hollow elastic core rod.
[0029] The diaphragm is then wound onto the surface of the hollow elastic core rod, followed by the positive and negative electrode sheets. Once the winding is complete, the battery cell is obtained.
[0030] Method 2:
[0031] A diaphragm is wound around a hollow rod, and then positive and negative electrode plates are rolled in.
[0032] After winding, sealant tape is attached to one side, and bagged electrolyte is placed in the internal cavity of the hollow rod. Then, sealant tape is attached to the other side to obtain the battery cell.
[0033] Compared with the prior art, this application has the following beneficial effects:
[0034] 1) This patent uses a hollow elastic core rod to replace the alloy material used in the original core rod. It plays a supporting role during the cycle and can gradually compress the elastic core as the internal pressure of the core increases during the cycle, slowly releasing space to reduce the pressure on the inner ring and ensure that the electrode roll does not deform. A high-concentration lithium salt electrolyte is filled in the center of the elastic material core rod. When the pressure increases in the later stage of the cycle, the electrolyte is squeezed out of the core rod, making up for the loss of lithium salt electrolyte in the original cell.
[0035] 2) Furthermore, the inner wall of the hollow rod is provided with protrusions that deform under external pressure, which are used to break the bagged electrolyte. The protrusions facilitate the electrolyte to be squeezed out of the core rod, and the optimal time for replenishing the bagged electrolyte can be better controlled according to the degree of deformation of the hollow elastic core rod.
[0036] 3) Furthermore, the electrolyte in the bagged electrolyte contains flame retardants or heat resistant agents, which enables the cell and battery to maintain good flame retardant or heat resistant properties during use. Attached Figure Description
[0037] Figure 1 This is a component diagram of the hollow elastic mandrel of Embodiment 1 of this utility model;
[0038] Figure 2 This is a schematic diagram of the internal structure of the hollow rod in Embodiment 1 of this utility model;
[0039] Figure 3 This is an overall schematic diagram of the hollow elastic core rod of Embodiment 1 of this utility model;
[0040] Figure 4 This is a schematic diagram of a battery cell including an elastic core rod according to Embodiment 1 of this utility model;
[0041] Figure 5 This is a schematic diagram illustrating the working principle of the battery cell containing an elastic core rod under compression in Embodiment 1 of this utility model.
[0042] Figure label:
[0043] 1. Hollow rod; 2. Sealing tape; 3. Bagged electrolyte; 4. Protrusion; 5. Diaphragm; 6. Internal pressure. Detailed Implementation
[0044] To make the present technical solution clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example
[0045] A hollow elastic mandrel, the component diagram of which is shown below. Figure 1 A schematic diagram of the internal structure of hollow rod 1 is shown below. Figure 2 A schematic diagram of the hollow elastic core rod is shown below. Figure 3 .
[0046] A hollow elastic core rod includes a hollow rod 1, a sealing tape 2, and a bagged electrolyte 3, wherein the bagged electrolyte 3 is disposed inside the hollow rod 1; and the sealing tape 2 is disposed at both ends of the hollow rod 1 containing the bagged electrolyte 3.
[0047] The hollow rod 1 is made of an elastic material, such as elastic hard rubber or fluororubber, which is resistant to electrolyte corrosion, has a certain degree of support, and can be slightly deformed under high pressure. The inner wall of the hollow rod 1 is provided with protrusions 4 that are squeezed and deformed under external pressure to break the bagged electrolyte 3. In this embodiment, the elastic material is fluororubber.
[0048] The dimensions of the hollow rod 1, including length and diameter, can vary depending on the battery cell design to accommodate cells of various heights. The hollow rod 1 is hollowed out internally, ensuring it can withstand the winding tension of the winding machine. The hollow rod 1 has protrusions 4 such as... Figure 2 As shown, it is integrally formed with the hollow rod 1 and is made of the same material. Under external pressure, the hollow rod 1 is squeezed and deformed, breaking the packaging bag of the bagged electrolyte 3.
[0049] The electrolyte in the bagged electrolyte 3 is a high-concentration lithium salt electrolyte. The packaging bag for the bagged electrolyte 3 can be made of electrolyte-resistant plastics such as PE or PP (PP is used in this embodiment). The diameter of the bagged electrolyte needs to be slightly smaller than the difference between the inner diameter of the hollow rod 1 and the height of the protrusion 4, so as to facilitate the placement of the bagged electrolyte 3 inside the hollow rod 1. The thickness of the packaging bag is sufficient to be punctured by the protrusion 4 inside the core rod when the hollow rod 1 deforms. The internal electrolyte can be the same electrolyte as that of the battery. In this application, a specially designed electrolyte is used, and a flame retardant is added to the electrolyte to replenish the consumed electrolyte in the later stages of the cycle and improve the cycle performance.
[0050] The sealing tape 2 at both ends of the hollow rod 1 can be made of ordinary PE, PP or other materials (PP is used in this embodiment) to seal both ends of the hollow rod 1. The diameter of the sealing tape 2 must be large enough to completely cover the hollow holes at both ends of the hollow rod 1.
[0051] A battery cell comprising a hollow elastic core rod can be prepared using either method one or method two:
[0052] Method 1:
[0053] The bagged electrolyte is placed in the hollow rod 1, and then the two ends of the hollow rod 1 are sealed with sealing tape 2 to obtain a hollow elastic core rod.
[0054] Install the hollow elastic mandrel onto the winding machine, clamping both ends tightly, ensuring the sealing tape at both ends is not damaged.
[0055] The process begins with applying tape to the diaphragm 5 and then winding it up. The positive and negative electrode sheets are then wound in. Once winding is complete, the sealing tape 2 is checked for damage. If damaged, it is reapplied to obtain the battery cell. This embodiment uses Method 1 to prepare the battery cell.
[0056] Method 2:
[0057] Take the hollow rod 1 and install it on the winding machine; start winding by applying tape to the diaphragm 5 as usual, and then wind in the positive and negative electrode sheets; after winding is completed, apply sealing tape 2 to one side, put in the bagged electrolyte 3, and then apply sealing tape 2 to the other side.
[0058] A schematic diagram of a battery cell including a flexible core rod, as shown below. Figure 4 As shown in the diagram, this illustrates the working principle under compression. Figure 5 As shown, specifically, the increased internal pressure 6 of the battery cell during the later stages of the cycle compresses the elastic core rod, causing the protrusion 4 inside the elastic core rod to puncture the packaging bag of the electrolyte 3. The electrolyte is then released into the battery cell through both ends to replenish the electrolyte consumed during the cycle and improve the cycle life.
[0059] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.
Claims
1. A hollow elastic mandrel, characterized in that, It includes a hollow rod, sealing tape, and bagged electrolyte, wherein the bagged electrolyte is disposed inside the hollow rod; and the sealing tape is disposed at both ends of the hollow rod containing the bagged electrolyte.
2. The hollow elastic mandrel according to claim 1, characterized in that, The hollow rod is made of an elastic material.
3. A hollow elastic mandrel according to claim 2, characterized in that, The elastic material is elastic hard rubber or fluororubber.
4. A hollow elastic mandrel according to claim 1, characterized in that, The inner wall of the hollow rod is provided with protrusions that are used to break the packaging bag of the electrolyte when the hollow rod is squeezed and deformed.
5. A hollow elastic mandrel according to claim 4, characterized in that, The diameter of the bagged electrolyte is smaller than the difference between the inner diameter of the hollow rod and the height of the protrusion.
6. A hollow elastic mandrel according to claim 1, characterized in that, The sealing tape is made of plastic; the packaging bag for the electrolyte is also made of plastic.
7. A hollow elastic mandrel according to claim 6, characterized in that, The packaging bag for the electrolyte is made of PE or PP; the sealing tape is made of PE or PP.
8. A hollow elastic mandrel according to claim 1, characterized in that, The electrolyte in the bagged electrolyte can be the same electrolyte as that used in the battery or an electrolyte containing flame retardants or heat resistant agents.