Stepped Cylindrical Cell Lid for Venting and Electrolyte Filling

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Solution Overview

Problem

Existing rechargeable battery designs face challenges in production speed, cost, and structural integrity, particularly in cylindrical secondary cells, which affect manufacturing efficiency and energy performance.

Innovation Solution

A cylindrical secondary cell design featuring a lid with distinct regions, including a central electrolyte filling hole, venting regions, and a stepped profile to enhance structural rigidity and simplify assembly, while ensuring reliable gas venting and electrolyte filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional flat lid design is used, then the manufacturing process is simple, but the structural rigidity is insufficient and assembly alignment is difficult

Engineering Contradiction:

Improvestructural rigidityVSAvoidlid structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The lid is divided into multiple functional regions (first region for electrolyte filling, second region for venting, third region for sealing) arranged in a stepped configuration. This segmentation provides both structural rigidity through the stepped profile and defines clear functional zones, resolving the contradiction between strength and complexity by making the complexity purposeful rather than arbitrary.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The lid transitions from a traditional flat two-dimensional structure to a three-dimensional stepped structure with multiple levels. The first, second, and third regions are arranged at different heights, creating a stepped profile that enhances structural rigidity while providing distinct functional zones for electrolyte filling, venting, and sealing operations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the electrolyte filling hole is not centrally positioned, then manufacturing flexibility is higher, but assembly alignment becomes difficult and filling consistency varies

Engineering Contradiction:

Improveelectrolyte filling consistencyVSAvoidassembly alignment requirements

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The first region is positioned asymmetrically on the lid surface, breaking the traditional symmetric design. This asymmetric positioning of the electrolyte filling hole ensures consistent alignment during assembly while the stepped configuration maintains manufacturing precision. The asymmetry is deliberate and functional, resolving the contradiction by providing both alignment consistency and manufacturing flexibility.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If multiple vents are added to improve gas venting reliability, then safety is enhanced, but the lid structure becomes more complex and material usage increases

Engineering Contradiction:

Improvegas venting reliabilityVSAvoidmaterial usage

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

Multiple venting functions are merged into the second region of the lid, which is specifically designed for gas venting. The stepped configuration allows this region to accommodate multiple vent holes or a complex venting structure efficiently, achieving reliable gas venting while minimizing material usage through the integrated design.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The second region is designed with local quality enhancement, concentrating venting functionality in a specific area of the lid. This localized approach allows multiple vents to be arranged efficiently in the second region without increasing overall lid complexity or material usage significantly, resolving the contradiction between reliability and material consumption.

Inventive Principle:

Principle #3Local quality

4Strength

If the lid regions are joined with varying material thickness, then manufacturing is easier, but structural weakness occurs at seam locations

Engineering Contradiction:

Improveseam strengthVSAvoidlid fabrication difficulty

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The material thickness parameter is controlled to remain substantially constant across the transitions between first, second, and third regions. This parameter control ensures that seams between regions have uniform strength and do not create weak points, while the stepped configuration is achieved through controlled geometry rather than variable thickness, maintaining ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4679579A1Lid closure for a secondary cell

Publication Date: 2026.01.14 NORTHVOLT AB

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Figure 2A~3B
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AI summary

There is disclosed herein a cylindrical secondary cell (2000), comprising a cylindrical casing (234) housing an electrode assembly (232), and a lid (200) for closing an open end (234b) of the cylindrical casing (234). The lid (200) comprises a first region (201) extending in a first plane (204), a second region (202) surrounding the first region (201) and extending in a second plane (205) displaced in a first direction from the first plane (201), and a third region (203) surrounding the second region (202) and extending in a third plane (206) displaced in the first direction from the second plane (202). The first region (201) comprises an electrolyte filling hole (207), and the second region comprises a vent (208) configured to vent gases from the cylindrical casing (234). There is also disclosed herein a battery pack including such a cell, and a vehicle including such a battery pack.