Description:FIELD OF THE INVENTION
The subject matter of the present disclosure broadly relates to the field of battery. Particularly, the present disclosure relates to the support structure for a cylindrical secondary battery.
BACKGROUND OF THE INVENTION
Electric vehicles (EVs) have revolutionized the automotive industry, offering substantial environmental benefits through zero carbon emissions and reduced operating costs. A key component that contributes to the performance and efficiency of EVs is the battery. Different types of batteries are utilized in EVs, each selected based on specific vehicle requirements. Among the various battery formats, cylindrical batteries have gained increasing preference due to their excellent heat dissipation capabilities and overall performance advantages. In particular, large-format cylindrical batteries, such as the 4680 format, have attracted significant attention for their potential in EV applications.
Cylindrical batteries are typically constructed by winding the cathode, anode, and separator with a hollow core at the center, which serves as the reservoir for the electrolyte. However, a critical issue that can arise in these batteries is core collapse or deformation. This occurs when structural misalignment happens within the jelly-roll configuration, causing the hollow core to collapse and fill the empty space. The primary cause of core collapse is the expansion of the active materials' lattice structure during the battery’s charging and discharging cycles. This collapse can lead to the peeling of the active material, a sudden loss of battery capacity, damage to the separator, and even result in catastrophic thermal runaway.

Currently, several solutions have been proposed to prevent core collapse. One approach involves using heat to bond the separator to the core to maintain stability. However, this method is complicated by the potential for damage to the separator, especially when applying heat after core formation. Additionally, separators with ceramic coatings cannot be thermally fused, which further complicates the process.
Therefore, there is a need for a more effective and straightforward solution to provide structural support within cylindrical batteries, one that can suppress core collapse, enhance core stability, and offer long-term durability, without risking damage to sensitive components such as the separator. A flexible core support system that addresses these issues is essential for improving the performance and longevity of cylindrical batteries.
BRIEF DESCRIPTION OF FIGURES
Fig. 1 depicts the exploded view of the jelly-roll with the core-tube for a cylindrical battery cell, according to embodiments as disclosed herein;
Fig. 2 depicts a perspective view of the core tube, according to embodiments as disclosed herein;
Fig. 3 depicts a cross-sectional view of the core tube, according to embodiments as disclosed herein.
DETAILED DESCRIPTION OF THE INVENTION
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The term “support structure” represents the core-tube of the present invention. The term “secondary battery” refers to any rechargeable battery (i.e.) for example Li ion batteries, Na ion batteries, metal hydride batteries, metal air batteries, Li-S batteries and the like.
The present subject matter relates to the structure of the core tube for the cylindrical cells. As discussed in the background there is a dire need for a core tube design that provides adequate support to the core thus suppressing the core collapse and improving the cycle life of the battery.
Fig. 1 illustrates an exploded view of the jelly roll 10 with the core tube assembly, as per one embodiment of the present invention. The jelly roll 10 includes an anode, a cathode, and a separator placed between them. The anode, cathode, and separator are stacked together and wound to form a core, which extends along the axial direction, with the core tube 100 positioned at the center of the jelly roll.
Fig. 2 provides a perspective view of the core tube 100. The core tube 100 of the present invention consists of a head portion (100), a body portion (110), and a tail portion (130). The head portion (100) is divided into a first portion 100A and a second portion 100B. The first portion has a larger diameter than the second portion. The larger-diameter portion (9 to 11 mm) serves as the fixing component, securing the core tube within the jelly roll at the top. The second portion, with a diameter between 6.5 mm and 6.7 mm, provides additional structural support to the jelly roll.
The body portion 110 of the core tube features slitted arms 110A, each having a diameter between 6.5 mm and 6.7 mm. These slitted arms allow for easy insertion of the core tube into the jelly roll core. The gap width between the slitted arms ranges from 2.3 mm to 2.7 mm, allowing the core tube to flex during the battery's charge and discharge cycles, while providing structural support to the jelly roll.
The slitted arms also include holes 120 distributed along the axial direction. These holes are arranged in a way that ensures the structural integrity of the core tube, providing the necessary radial pressure while also enhancing electrolyte infiltration. No holes are present in the head portion to maintain the core tube's rigidity. The holes are evenly spaced across both arms.
The tail portion 130 of the core tube 100 is shaped with a pointer-like inward curvature. This curvature facilitates easy insertion of the core tube into the jelly roll core without damaging the separator. The inward curvature angle ranges from 30° to 60°. Angles below 30° result in insufficient space for proper electrolyte filling, while angles above 60° could cause misalignment or damage to the separator during insertion.
The invention is primarily focused on the use of the core tube in 4680 cylindrical cells. However, it should be understood that the invention is also applicable to other form factors, designs, shapes, chemistries, cap assemblies, and similar configurations, provided they incorporate the core tube.
The support structure of the present invention provides structural support to the jelly roll thus suppressing the core deformation/collapse. Also the slitted arms in the tail portion provides flexibility during the charging and discharging without compromising the structural strength. The holes in the arms as well as the width of the slitted arms enables the proper wettability of the electrolyte throughout the jelly roll. The support structure can be inserted after the formation of the jelly-roll without disrupting the core structure.
Although examples for the present disclosure have been described in language specific to structural features and/or methods, it is to be understood that these examples are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present description.

, Claims:We Claim:
1. A secondary battery comprising:
a cylindrical casing;
a jelly-roll disposed within the cylindrical casing;
a support structure located within the hollow core of the jelly-roll, wherein the support structure comprising;
a head portion (100) having a solid hollow cylindrical tube;
a body portion (110); and
a tail portion (130) that includes slitted arms (110).
2. The secondary battery of claim 1, wherein the head portion (100) has a top portion (100A) with a diameter larger than the bottom portion (100B).
3. The secondary battery of claim 1, wherein the body portion (110) includes two slitted arms (110).
4. The secondary battery of claim 1, wherein the tail portion (130) has a smaller diameter than the head portion (100) and the body portion (110).
5. The secondary battery of claim 1, wherein the tail portion (130) is curved inward at an angle ranging from 30° to 60°.
6. The secondary battery of claim 1, wherein the slitted arms (110) include holes (120).
7. The secondary battery of claim 1, wherein the holes (120) are evenly distributed in both the arms (110A).
8. The secondary battery of claim 1, wherein the diameter of the holes (120) in the slitted arms (110A) ranges between 2 mm and 3 mm.