Snap-through Deformation for Stable Battery Actuation Pressure
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Solution Overview
Problem
Current-blocking systems in sealed secondary batteries, particularly those used in vehicles, experience a significant change in actuation pressure over time due to the decrease in fracture strength of current collector plates caused by long-term use and internal pressure fluctuations, leading to inconsistent performance.
Innovation Solution
The implementation of a current-blocking system that utilizes a pressure-sensitive member with a deformable portion undergoing snap-through deformation to disconnect the conduction path, maintaining a consistent actuation pressure by adjusting the shape and thickness of the pressure-sensitive member to ensure proper snap-through deformation at a prescribed pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a current collector plate with a groove is used to control actuation pressure, then the actuation pressure can be set within a prescribed range, but the actuation pressure changes significantly over long-term use due to decrease in fracture strength
Solution Approach 1:
The patent changes the control parameter from fracture strength (groove depth) to elastic deformation characteristics (thickness and elastic modulus). By making the invertible plate thinner and using materials with appropriate elastic modulus, the actuation pressure is controlled by elastic bending rather than fracture, preventing the pressure drift that occurs with long-term use.
Solution Approach 2:
The invertible plate is designed as a disposable component that undergoes permanent deformation (snap-through) at the prescribed actuation pressure. Once activated, it permanently blocks the current path, sacrificing the plate itself to protect the battery. This eliminates the need for the plate to maintain precise mechanical properties over long periods.
2Stress or pressure
If the current collector plate is made thinner to reduce actuation pressure, then the actuation pressure decreases, but the plate becomes more susceptible to long-term degradation and fracture
Solution Approach 1:
The patent changes the failure mode from fracture to elastic snap-through deformation. By controlling the thickness and elastic modulus, the plate can be made thin enough to achieve low actuation pressure while maintaining sufficient strength to withstand long-term use through reversible elastic deformation cycles.
Solution Approach 2:
The invertible plate is designed to dynamically respond to pressure changes through reversible elastic deformation during normal operation, then undergo an irreversible snap-through transition at the critical actuation pressure. This dynamic behavior allows the plate to be thin and flexible without compromising long-term reliability.
3Duration of action of stationary object
If internal pressure increases over long-term use, then the battery operates normally, but the fracture strength of the current collector decreases leading to premature activation
Solution Approach 1:
The patent changes the activation mechanism from fracture-based to elastic-deformation-based. The actuation pressure is determined by the elastic snap-through transition pressure, which remains stable over time, rather than by fracture strength which degrades with prolonged exposure to internal pressure.
Solution Approach 2:
The groove structure serves as a predetermined weak point that guides the snap-through deformation. This pre-designed feature ensures that the plate activates at the correct pressure through controlled elastic instability, preventing premature activation due to manufacturing variations or long-term degradation.
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
This configuration effectively maintains a stable actuation pressure over the long term, preventing premature activation and ensuring reliable performance in sealed secondary batteries, especially in vehicle applications.
Implementation Method 1
the pressure-sensitive deformable portion deforms from a first state via snap-through deformation to a second state
Data Source
AI summary
There is provided a sealed secondary battery whose current-blocking system yields little change in the actuation pressure even on long-term use. The sealed secondary battery comprises a current-blocking system 80 that is actuated by a pressure rise inside a battery case 12 to disconnect conduction path between an electrode and an electrode terminal. Current-blocking system 80 comprises a pressure-sensitive member having a pressure-sensitive deformable portion 32 that deforms from a first state via snap-through deformation to a second state upon a pressure rise inside battery case 12, and is configured to disconnect the conduction path by snap-through deformation of pressure-sensitive deformable portion 30.