Cylindrical Secondary Battery Leak Detection and Tab-Less Current Collection
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Solution Overview
Problem
Cylindrical secondary batteries face issues with electrolyte leakage and heat generation due to concentrated electric current at electrode tabs, leading to potential ignition during rapid charging, especially in large form factors used for electric vehicles.
Innovation Solution
A secondary battery design with a tab-less structure and real-time electrolyte leak detection using a leak detection member positioned between the electrode terminal and gasket, utilizing a leak detection material that changes color upon contact with electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gasket is positioned between the electrode terminal and battery casing to prevent electrolyte leakage, then sealing reliability is improved, but it becomes impossible to quickly detect whether electrolyte leaks occur
Solution Approach 1:
The patent applies a color-changing leak detection material on the outer surface of the battery casing that changes color when it comes into contact with leaking electrolyte. This allows visual detection of leaks while maintaining the sealing function of the gasket, thus resolving the contradiction between reliable sealing and leak detectability.
2Ease of manufacture
If electrode tabs with strip shapes are used to connect positive and negative electrodes, then manufacturing is simplified, but electric current concentrates on the tabs causing increased resistance and heat generation
Solution Approach 1:
The patent segments the electrode connection structure by introducing multiple current collectors distributed across the electrode surface instead of using single strip-shaped tabs. This segmentation distributes the electric current across multiple contact points, reducing current density and heat generation at any single point while maintaining manufacturing feasibility.
Solution Approach 2:
The patent transitions from one-dimensional strip-shaped tabs to a two-dimensional distributed array of current collectors across the electrode surface. This dimensional change increases the effective contact area and distributes current more evenly, reducing resistance and heat generation.
3Quantity of substance
If the battery form factor is increased for electric vehicle application, then energy capacity is improved, but heat generation around the electrode tab increases leading to potential ignition during rapid charging
Solution Approach 1:
The patent segments the current collection system into multiple distributed current collectors, which distributes the high current loads during rapid charging across multiple points. This reduces the heat generation density at any single location, mitigating the ignition risk associated with large form factor batteries used in electric vehicles.
Solution Approach 2:
The patent introduces an intermediary cooling structure between the electrode assembly and the battery casing that facilitates heat dissipation. This intermediary element acts as a thermal management system that prevents heat accumulation around the electrode tabs, reducing the risk of ignition during high-rate charging operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables real-time detection of electrolyte leaks, preventing potential ignition and improving safety by maintaining close-contact force between the electrode terminal and gasket, thus enhancing current collection efficiency and reducing heat generation.
Implementation Method 1
utilizing a leak detection material that changes color upon contact with electrolyte
Data Source
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AI summary
The present disclosure relates to a secondary battery including an electrode assembly made by winding a positive electrode, a separator, and a negative electrode, a battery casing having one surface with an opening, and the other surface having a through-hole, the battery casing having a space in which the electrode assembly is accommodated, an electrode terminal provided to be in contact with the electrode assembly and exposed to the outside through the through-hole, a gasket positioned between the battery casing and the electrode terminal, and a top cap coupled to the opening of one surface of the battery casing, in which first leak detection member is positioned on a surface of the gasket that faces the battery casing.