Bottom lid of a cylindrical battery

Abstract

An electrochemical cell (100) comprises a cylindrical can (122) with a closed end (122a) and an open end (122b). Inside the can (122), a jelly roll (114) is positioned, comprising a positive electrode, a negative electrode, and a separator wound together. The bottom lid (116) is placed at the open end (122b) of the can (122), and an upper terminal (102) is located at the closed end (122a). The bottom lid (116) has a stepped edge portion (124) that exerts an upward force on the jelly roll (114), pushing it towards the upper terminal (102). This configuration enhances the secure electrical contact between the jelly roll (114) and the upper terminal (102), ensuring stable performance by maintaining component alignment within the cylindrical can (122) (See FIGs. 3 and 4).

Description

[0001] BOTTOM LID OF A CYLINDRICAL BATTERY

[0002] FIELD OF INVENTION

[0003] Embodiments of the present application relates to electrochemical cells, specifically focusing on cylindrical lithium-ion battery designs. It involves optimizing internal component alignment and electrical connectivity to enhance performance and reliability. This technology addresses challenges in maintaining stable mechanical integrity and ensuring robust electrical connections in high-performance battery applications.

[0004] BACKGROUND OF THE INVENTION

[0005] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently disclosed invention, or that any publication specifically or implicitly referenced is prior art.

[0006] In the manufacturing of cylindrical battery cells, it is critical to ensure proper assembly and secure connections between internal components, such as the jelly roll, upper rivet / terminal, and the outer can. Proper alignment and contact between these elements directly impact the cell's electrical performance, mechanical integrity, and overall reliability. However, certain assembly issues can arise due to variations in component dimensions and tolerances, leading to misalignments, gaps, and unstable connections within the cell.

[0007] One common issue observed during assembly is the presence of a gap between the jelly roll and the upper rivet / terminal. This misalignment occurs when the height of the jelly roll varies relative to the outer can. Such height variations can be attributed to differences in the thickness of the electrode materials, irregular winding of the jelly roll, or discrepancies in the dimensions of the outer can. Consequently, when the cell is assembled, the upper rivet / terminal does not establish a consistent and secure contact with the jelly roll, resulting in unreliable electrical performance and potentially impacting the overall quality and safety of the cell.

[0008] Attempts to address the height discrepancy by modifying the bottom lid have been made, such as altering its circumference or adding compensatory structures. While these modifications may help align the jelly roll and the upper rivet / terminal, they often introduce a secondary issue: a gap forms between the modified bottom lid and the outer can, creating unwanted play or movement during assembly. This looseness can cause misalignment of the internal components, leading to structural instability and potential damage to the jelly roll or other parts during the assembly process.

[0009] Thus, there is a need for an improved design that addresses both the height variation of the jelly roll and the resultant gap between the bottom lid and the outer can, ensuring proper alignment, stable connections, and secure assembly of the cell components. Overcoming these challenges would enhance the mechanical stability and electrical performance of the assembled battery cell, providing a more reliable solution for high-performance applications.

[0010] SUMMARY OF THE INVENTION

[0011] The following presents a simplified summary of the subject matter in order to provide a basic understanding of some of the aspects of subject matter embodiments. This summary is not an extensive overview of the subject matter. It is not intended to identify key / critical elements of the embodiments or to delineate the scope of the subject matter. Its sole purpose to present some concepts of the subject matter in a simplified form as a prelude to the more detailed description that is presented later.

[0012] An electrochemical cell described in this disclosure provides a solution to the need for an enhanced design that effectively manages the height variation of the jelly roll within the cell and eliminates the gap between the bottom lid and the outer can. By addressing these issues, the cell ensures precise alignment of the internal components, stable electrical connections, and a secure assembly structure. Resolving these challenges contributes to improved mechanical integrity and optimized electrical performance, making the cell assembly more robust and reliable for high-performance applications. This design refinement not only prevents misalignment and potential electrical failures but also supports consistent performance in demanding operational environments.

[0013] The electrochemical cell (100) includes a cylindrical can (122) with a closed end (122a) and an open end (122b). Inside the cylindrical can (122) is a jelly roll (114) composed of a positive electrode, a negative electrode, and a separator, all wound together. A bottom lid (116) is located at the open end (122b) of the can, and an upper terminal (102) is situated at the closed end (122a). The bottom lid (116) features a stepped edge portion (124) that pushes the jelly roll (114) upwards to ensure secure electrical contact between the jelly roll (114) and the upper terminal (102). In an embodiment, the stepped edge portion (124) of the bottom lid (116) has a height that adjusts to variations in the jelly roll’s (114) height, allowing alignment and secure electrical contact between the jelly roll (114) and an upper current collector (126), which in turn connects with the upper terminal (102).

[0014] In an embodiment, the stepped edge portion (124) is approximately 1 mm in height, which compensates for height variations in the jelly roll (114) to ensure firm contact between the upper current collector (126) and the upper terminal (102). In an embodiment, the stepped edge portion (124) also prevents gaps from forming between the jelly roll (114) and the upper terminal (102), reducing electrical resistance and promoting consistent current flow within the electrochemical cell (100). In an embodiment, the stepped edge portion (124) of the bottom lid (116) has a slightly larger outer diameter (124a) than the inner diameter (122c) of the cylindrical can (122), allowing it to be press-fitted into the open end (122b) of the can (122) for a secure fit that provides structural stability and alignment.

[0015] In an embodiment, the outer diameter (124a) of the stepped edge portion (124) of the bottom lid (116) is sized to create an interference fit with the cylindrical can (122), ensuring a stable mechanical connection that prevents lateral and axial movement during assembly and operation. In an embodiment, the press-fit design of the bottom lid (116) also reduces assembly-related defects by keeping the jelly roll (114) precisely aligned with the upper terminal (102), which enhances the mechanical integrity and reliability of the electrochemical cell (100). In an embodiment, the stepped edge portion’s (124) outer diameter (124a) is carefully measured to create a press-fit with the cylindrical can (122) without causing distortion to the can (122), preserving the can’s structural integrity. Together, the stepped edge portion (124) on the bottom lid (116) and the press-fit configuration ensure that the jelly roll (114) is securely positioned, preventing displacement during both cell assembly and operation.

[0016] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0017] The following drawings are illustrative of particular examples for enabling systems and methods of the present disclosure, are descriptive of some of the methods and mechanism, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.

[0018] FIGURE 1 shows exploded view of a cylindrical battery.

[0019] FIGURE 2 shows a cylindrical battery having flat edged bottom lid, showing current collector not touching with terminal and without having a step in the bottom lid.

[0020] FIGURE 3 shows partial exploded view of an electrochemical cell or cylindrical battery of the present disclosure, showing current collector touching with terminal and with a step arrangement in the bottom lid, as an example embodiment of the present disclosure.

[0021] FIGURE 4 shows partial exploded view of an electrochemical cell or cylindrical battery of the present disclosure with step in the bottom lid showing the seating or mating surface, as an example embodiment of the present disclosure.

[0022] FIGURES 5A-5D show perspective views of the electrochemical cell with step in the bottom lid, wherein FIGURE 5D shows detailed view of the step, as an example embodiment of the present disclosure.

[0023] FIGURES 6A-1 and 6A-2 show a top perspective view and a sectional perspective view of the bottom lid outside the cell, showing vent profile at outer surface of the cell, as an example embodiment of the present disclosure.

[0024] FIGURES 6B-1 and 6B-2 show a top perspective view and a sectional perspective view of the bottom lid inside the cell, showing jelly roll seating area and laser welded, as an example embodiment of the present disclosure.

[0025] FIGURES 7A and 7B show perspective views of the electrochemical cell with step in the bottom lid, where FIGURE 7B shows gap ranging from 0.10mm to 1mm causing play in bottom Lid due to the step arrangement, as an example embodiment of the present disclosure. FIGURES 8A and 8B show perspective views of the electrochemical cell with step in the bottom lid, where FIGURE 8B shows the bottom lid’ s outer diameter that is designed to create an interference fit with the cylindrical can, as an example embodiment of the present disclosure.

[0026] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may represent hardware components of the system. Further, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0028] Exemplary embodiments now will be described. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. The terminology used in the detailed description of the particular exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting. In the drawings, like numbers refer to like elements.

[0029] It is to be noted, however, that the reference numerals used herein illustrate only typical embodiments of the present subject matter, and are therefore, not to be considered for limiting of its scope, for the subject matter may admit to other equally effective embodiments.

[0030] The specification may refer to “an”, “one” or “some” embodiment s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0031] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and / or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include operatively connected or coupled. As used herein, the term “and / or” includes any and all combinations and arrangements of one or more of the associated listed items.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0033] Referring to FIGURE 1, the definition of each component is listed below:

[0034] 1. Rivet (Positive Terminal) (102): The terminal that connects to the positive side of the battery, allowing current to flow out of the battery when it is in use.

[0035] 2. Rivet Gasket (104): Provides insulation around the rivet, ensuring a secure and stable position within the battery structure to prevent short circuits.

[0036] 3. Cathode Disc (106): Acts as the positive electrode, typically made of a material that facilitates ion movement, contributing to the battery's electrochemical reactions.

[0037] 4. Cathode Insulator (108): An insulating layer that separates the cathode disc from other components, maintaining battery stability and preventing electrical shorts.

[0038] 5. Retention Tape (Top) (110): Secures the upper part of the internal components, helping to keep them in place during battery operation and handling.

[0039] 6. Retention Tape (Bottom) (112): Similar to the top retention tape (110), the bottom retention tape (112) secures the lower part of the battery’s internal structure.

[0040] 7. Jelly Roll (114): A spiral-wound assembly of anode, cathode, and separator layers, maximizing contact surface area to enhance the battery’s energy storage capacity.

[0041] 8. Bottom Lid / Anode Lid (116): The cover on the negative side of the battery, acting as a point of contact for the anode and contributing to the battery's overall enclosure. 9. Sealing Plug (118): A component that seals the battery, preventing leaks of electrolytes and maintaining internal pressure for safety.

[0042] 10. Closing Pin (120): Secures the battery casing, holding all internal components firmly in place to ensure the battery remains intact under various conditions.

[0043] 11. Can (122): Refers to the outer casing or enclosure of the battery. It is typically a cylindrical or rectangular metal container that houses all internal components, such as the jelly roll (or electrode assembly), electrolyte, and other structural parts

[0044] Referring to FIGURES 1 (described above) and 2, a cylindrical battery (100) with a flat-edged bottom lid (116) is shown, illustrating an example where the current collector (126) does not make contact with the upper terminal (102) and lacks a stepped edge (124) in the bottom lid (116). The battery (100) is constructed using a cylindrical can (122) that houses the complete internal assembly, including the jelly roll (114) structure, which consists of a positive electrode, a negative electrode, and a separator wound together along the central axis to form a stable core. Retention tapes (110 and 112) are applied at both the top and bottom of the jelly roll (114) to prevent the separator from unwinding, ensuring the layers remain in place. At the top of the jelly roll (114), an upper current collector (126) is positioned to establish the positive connection from the electrode tabs, which is directed upward for terminal connectivity. To avoid short circuits, a cathode insulator is added around the upper current collector (126), preventing it from contacting the inner surface of the can (122), which is connected to the bottom lid (116) and serves as the battery’s negative terminal.

[0045] The positive terminal (102) is formed using a rivet at the top of the assembly, which is insulated from the can (122) using a rivet gasket. The gasket, compressed to 30-40% of its original size, prevents leakage and ensures that the rivet (positive terminal) does not electrically connect to the can body (negative terminal), thus maintaining the separation between the two. The rivet also helps secure the upper current collector (126) and other components in place, ensuring a firm and reliable structure for the positive connection.

[0046] The battery’s bottom lid (116), also referred to as the anode lid or negative lid, is welded directly to the negative electrode tabs and to the circumference of the can (122), forming the battery's negative terminal. This lid incorporates a venting feature to release internal pressure in case of thermal runaway, ensuring safety during overheating. After electrolyte filling, a sealing plug is used to make the electrochemical cell (100) airtight, with a closing pin welded to the lower side of the bottom lid (116) to seal the entire structure, providing a stable and secure design for reliable operation.

[0047] Referring to FIGURES 3, 4, and 5A-5D, FIGURE 3 shows a partial exploded view of an electrochemical cell (100) with the current collector (126) making contact with the upper terminal (102) and with a stepped edge (124) in the bottom lid (116). FIGURE 4 shows a partial exploded view with the stepped edge (124) indicating the seating or mating surface, and FIGURES 5A-5D show perspective views of the electrochemical cell (100) with a stepped bottom lid (116), with FIGURE 5D showing a detailed view of the step as an example embodiment.

[0048] As shown in FIGURES 3-5D, the electrochemical cell (100) comprises a cylindrical can (122) with a closed end (122a) and an open end (122b). Inside the cylindrical can (122) is a jelly roll (114) composed of a positive electrode, a negative electrode, and a separator, all wound together. A bottom lid (116) is located at the open end (122b) of the can (122), and an upper terminal (102) is situated at the closed end (122a). The bottom lid (116) features a stepped edge portion (124) that pushes the jelly roll (114) upwards to ensure secure electrical contact between the jelly roll (114) and the upper terminal (102). In an embodiment, the stepped edge portion (124) of the bottom lid (116) has a height that adjusts to variations in the jelly roll’s (114) height, allowing alignment and secure electrical contact between the jelly roll (114) and an upper current collector (126), which in turn connects with the upper terminal (102).

[0049] To address the issue of inconsistent contact between the jelly roll (114) and the upper terminal (102) due to height variations in the assembly, a specially designed bottom lid (116) with the stepped edge portion (124) is introduced. This solution aims to eliminate the gap between the jelly roll (114) and the upper terminal (102), thereby ensuring reliable electrical connectivity and structural stability within the electrochemical cell (100). The bottom lid (116) is designed with a precisely dimensioned stepped edge portion (124) that compensates for the height variations observed in the jelly roll (114). The stepped edge portion (124) has a height of approximately ranging from 0.2 mm to 2 mm, calculated based on the cumulative height of the jelly roll (114), which ranges 70 to 80 mm, and the thickness of the upper current collector (126), which measures in a range of 0.1 mm to 0.5 mm. By incorporating a stepped edge portion (124) with a range of 0.5 mm to 1.5 mm height, the bottom lid (116) effectively pushes the jelly roll (114) upwards during assembly, ensuring that it makes firm contact with the upper terminal (102).

[0050] Key Features of the Stepped Edge Portion (124):

[0051] 1. Height Compensation and Proper Alignment: The stepped edge portion (124) on the bottom lid (116) compensates for height variations in the jelly roll (114) by pushing it upward, ensuring secure electrical contact between the jelly roll (114) and the upper terminal (102). The step height is calculated to range from approximately 1 mm to ensure the jelly roll (114) maintains alignment and reliable connectivity with the upper terminal (102). This adjustment prevents any gaps, minimizes electrical resistance, and ensures a consistent current flow.

[0052] 2. Gap Prevention: The stepped edge portion (124) also prevents gaps from forming between the jelly roll (114) and the upper terminal (102), reducing electrical resistance and promoting consistent current flow within the electrochemical cell (100).

[0053] 3. Secure Connection and Consistent Contact Pressure: The stepped edge portion (124) on the bottom lid (116) provides consistent contact pressure between the jelly roll (114) and the upper terminal (102), essential for reducing resistance and ensuring connection reliability during operation. By securely holding the jelly roll (114) in place, the stepped edge (124) prevents displacement, enhancing the structural stability of the battery (100).

[0054] Overall, the bottom lid (116) with a stepped edge (124) is a simple yet effective solution that resolves the problem of improper contact between the jelly roll (114) and the upper terminal (102). By eliminating the gap and ensuring proper alignment, the stepped bottom lid (116) design contributes to improved electrical performance, reduced internal resistance, and enhanced mechanical stability of the electrochemical cell (100), thereby increasing its overall reliability and lifespan.

[0055] FIGURES 6A-1 and 6A-2 show a top perspective view and a sectional perspective view of the bottom lid (116) outside the electrochemical cell (100), showing vent profile at outer surface of the electrochemical cell (100), as an example embodiment of the present disclosure. FIGURES 6B-1 and 6B-2 show a top perspective view and a sectional perspective view of the bottom lid (116) inside the electrochemical cell (100), showing jelly roll (114) seating area which is laser welded, as an example embodiment of the present disclosure.

[0056] Referring to FIGURES 7A-8B, FIGURES 7 A and 7B show the electrochemical cell (100) with the stepped bottom lid (116) highlighting a gap ranging from 0.10 mm to 1 mm due to the step arrangement, and FIGURES 8 A and 8B demonstrate the outer diameter (124a) of the stepped edge portion (124) of the bottom lid (116), designed to create an interference fit with the cylindrical can (122). To address unwanted movement between the bottom lid (116) and the cylindrical can (122), the outer diameter (124a) of stepped edge portion (124) of the bottom lid (116) is engineered to be slightly greater than the inner diameter (122c) of the can (122), enabling a secure press-fit connection. This design eliminates any play between the bottom lid (116) and the cylindrical can (122), ensuring stability during both assembly and operation.

[0057] The outer diameter (124a) of the stepped edge portion (124) is carefully measured to create a press-fit with the cylindrical can (122) without causing distortion to the can (122), preserving the can’s structural integrity. Together, the stepped edge portion (124) of the bottom lid (116) and the press-fit configuration ensure that the jelly roll (114) is securely positioned, preventing displacement during both cell assembly and operation. By doing so, the bottom lid (116) can be firmly positioned within the can (122), preventing any relative movement or instability that could arise during the assembly or operation of the electrochemical cell (100), thereby providing structural stability and alignment.

[0058] Key Aspects of the Improved Bottom Lid (116) Design:

[0059] 1. Precision Fit to Arrest Play: The outer diameter (124a) of the stepped edge portion (124) of the bottom lid (116) is sized to create an interference fit with the cylindrical can (122), ensuring a stable mechanical connection that prevents lateral and axial movement during assembly and operation. The slight difference in diameter allows a press-fit that effectively eliminates lateral or axial play, ensuring the bottom lid (116) remains firmly in place without distorting the can (122). If the outer diameter (124a) deviates from the calculated value, it may lead to deformation of the can’s lower region during press-fitting. In other words, since the outer diameter (124a) of the stepped edge portion (124) is marginally greater than the inner diameter (122c) of the can (122), this allows for a press-fit assembly, where the bottom lid (116) is securely inserted into the can (122), creating a tight interference fit.

[0060] 2. Avoiding damage during assembly: the slight increase in the outer diameter (124a) is carefully calculated to provide just enough pressure to eliminate any lateral or axial play, without causing excessive force that might damage the components or distort the can’s (122) shape. Additionally, if the stepped edge portion’s (124) diameter deviates from the specified calculated values or exceeds the required diameter for achieving a proper press-fit, it may result in damage to the lower circumferential region of the can (122) when pressure is applied during the press-fit process.

[0061] 3. Enhanced Structural Stability and Improved Assembly Efficiency: The press-fit configuration ensures that the bottom lid (116) is securely positioned, enhancing structural stability and simplifying the assembly process. This reduces the need for additional securing mechanisms or adhesives, contributing to higher assembly efficiency and production consistency. The press-fit mechanism enhances the structural stability of the assembled electrochemical cell (100) by ensuring that the bottom lid (116) remains firmly in place. This eliminates any gaps that could result from dimensional variations in the lid (116) or can (122), preventing shifting or misalignment during assembly or in-service conditions, such as vibration or thermal expansion. By achieving a rigid fit, the bottom lid (116) supports the overall integrity of the electrochemical cell (100), minimizing the risk of internal component displacement or electrical discontinuities.

[0062] 4. Improved Assembly Efficiency and Consistency: The slight increase in stepped edge portion (124) diameter simplifies the assembly process by providing a clear and consistent point of contact for press-fitting. This ensures that each assembly is uniform, reducing variability and improving overall production efficiency. The controlled press-fit design also reduces the need for additional securing mechanisms or adhesives, thereby streamlining the manufacturing process.

[0063] 5. Mitigation of Vibrational and Thermal Impact: During operation, battery cells are often subjected to vibrations and thermal cycling, which can exacerbate any looseness between the components. The tight press-fit of the bottom lid effectively mitigates these issues by maintaining a stable configuration, even under dynamic conditions. This stability is crucial in preventing wear, fretting, or deformation of the lid and can, which could otherwise compromise the cell's reliability and safety. 6. Ease in Welding: The press-fit design facilitates ease in welding, as the bottom lid (116) holds the jelly roll (114) in position throughout the welding process, maintaining proper alignment and producing a high-quality weld joint, thereby preventing any movement or misalignment. This ensures ease of welding and results in a high-quality weld joint. This improved bottom lid (116) design with the outer diameter slightly larger than the cylindrical can (122) offers a robust solution, securing stability and enhancing the electrochemical cell’s (100) reliability, durability, and overall performance.

[0064] 7. Reduction in possible defects during manufacturing: The press-fit design of the bottom lid (116) also reduces assembly-related defects by keeping the jelly roll (114) precisely aligned with the upper terminal (102), which enhances the mechanical integrity and reliability of the electrochemical cell (100). The press-fit configuration ensures a secure and stable connection, eliminating unwanted movement and enhancing the mechanical integrity of the assembled electrochemical cell (100). This improved design results in better alignment of internal components, enhanced durability, and reduced risks of assembly-related defects, thereby contributing to the overall reliability and performance of the electrochemical cell (100).

[0065] Current invention has been discussed specifically with full disclosure. However, numerous changes can be made in the detail of structures, combinations, and part arrangement along with technical advancements that will be implemented in near future without changing the spirit and scope of the invention.

[0066] Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore, contemplated that such modifications can be made without departing from the scope of the present invention as defined.

Claims

We Claim:

1. An electrochemical cell (100), comprising: a cylindrical can (122) comprising a closed end (122a) and an open end (122b); a jelly roll (114) disposed within the cylindrical can (122), the jelly roll (114) comprising a positive electrode, a negative electrode, and a separator wound together; a bottom lid (116) positioned at the open end (122b) of the cylindrical can (122); an upper terminal (102) disposed at the closed end (122a) of the cylindrical can (122); and a stepped edge portion (124) formed on the bottom lid (116), wherein the stepped edge portion (124) pushes the jelly roll (114) upwards to facilitate a secure electrical contact between the jelly roll (114) and the upper terminal (102).

2. The electrochemical cell (100) as claimed in claim 1, wherein the stepped edge portion (124) has a height that compensates for the variation in the height of the jelly roll (114), enabling contact with an upper current collector (126), which provides alignment and reliable electrical connectivity between the jelly roll (114) and the upper terminal (102).

3. The electrochemical cell (100) as claimed in claim 2, wherein the height of the stepped edge portion (124) is approximately 1 mm to compensate for variations in the jelly roll (114) height and to ensure that the upper current collector (126) is in firm contact with the upper terminal (102).

4. The electrochemical cell (100) as claimed in claim 1, wherein the stepped edge portion (124) prevents the formation of a gap between the jelly roll (114) and the upper terminal (102), which minimizes electrical resistance and ensures consistent current flow within the electrochemical cell (100).

5. The electrochemical cell (100) as claimed in claim 1, wherein the stepped edge portion (124) of the bottom lid (116) has an outer diameter (124a) slightly greater than an inner diameter (122c) of the cylindrical can (122), wherein the bottom lid (116) is press-fitted into the open end (122b) of the cylindrical can (122) to eliminate play between the bottom lid (116) and the cylindrical can (122), ensuring structural stability and alignment during assembly.

6. The electrochemical cell (100) as claimed in claim 5, wherein the outer diameter (124a) of the stepped edge portion (124) of the bottom lid (116) is designed to create an interference fit with the cylindrical can (122), to provide a secure and stable mechanical connection to prevent lateral and axial movement during assembly and operation.

7. The electrochemical cell (100) as claimed in claim 5, wherein the press-fit configuration of the bottom lid (116) reduces assembly-related defects by maintaining precise alignment between the jelly roll (114) and the upper terminal (102), which enhances the electrochemical cell’s (100) mechanical integrity and reliability.

8. The electrochemical cell (100) as claimed in claim 5, wherein the outer diameter (124a) of the stepped edge portion (124) of the bottom lid (116) is dimensioned to provide the press- fit configuration without causing distortion of the cylindrical can (122), which preserves the structural integrity of the outer cylindrical can (122).

9. The electrochemical cell (100) as claimed in claim 1, wherein the stepped edge portion (124) of the bottom lid (116), in conjunction with the press-fit configuration, ensures that the jelly roll (114) is held securely in position and prevents displacement during cell assembly and operation.

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