Cylindrical Secondary Battery Current Interruption by SMA Spring
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Solution Overview
Problem
Cylindrical secondary batteries face performance degradation and safety issues due to heat generation during fast-charging, necessitating a solution to ensure safety against heat-related hazards.
Innovation Solution
A secondary battery design incorporating a jelly-roll type electrode assembly with a shape memory alloy spring part that reduces distance between its highest and lowest points at elevated temperatures, releasing contacts between electrode extensions and other components to interrupt current flow and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast-charging is implemented to improve charging speed, then productivity is improved, but temperature increases causing safety issues and performance degradation
Solution Approach 1:
The patent converts the harmful effect of heat generation into a beneficial safety mechanism by using shape memory alloys that respond to temperature increases. When overheating occurs during fast-charging, the shape memory alloy components undergo phase transformation and automatically interrupt current flow, transforming the harmful thermal effect into a protective function that prevents safety incidents while allowing fast-charging to proceed under normal conditions
2Reliability
If a safety mechanism is added to interrupt current flow at high temperatures, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service safety mechanism where the shape memory alloy components automatically detect temperature increases and interrupt current flow without requiring external control systems, sensors, or complex control logic. The shape memory alloy's inherent phase transformation properties enable the battery to self-regulate and protect itself against overheating, achieving high reliability while minimizing added complexity
Solution Approach 2:
The patent utilizes parameter changes in the shape memory alloy's physical properties (phase transformation temperature) to create a passive thermal response mechanism. By selecting shape memory alloys with specific transformation temperatures, the safety mechanism activates automatically when temperature exceeds safe thresholds, providing reliable protection through material property changes rather than complex control systems
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
The design ensures structural stability and safety by effectively interrupting current flow at elevated temperatures, preventing performance degradation and potential explosions or ignitions.
Implementation Method 1
the spring part comprises a shape memory alloy, so that a distance between a highest point and a lowest point of the spring part decreases at a deformation temperature higher than a normal operating temperature range
Data Source
AI summary
A secondary battery may include: an electrode assembly in which a first electrode, a second electrode, and a separator are wound; a battery can; a cap assembly; a spacer; and a spring part. The first electrode may include a first electrode current collector and a first electrode extension part in which the first electrode current collector is exposed in a lower direction. The second electrode may include a second electrode current collector and a second electrode extension part in which the second electrode current collector is exposed in an upper direction. The first electrode extension part may contact the spacer. The second electrode extension part may contact the cap assembly. The spring part may include a shape memory alloy, so that a distance between a highest point and a lowest point of the spring part decreases at a deformation temperature higher than a normal operating temperature range.