Secondary Battery Current Interruption via Pressure-Actuated Displacement
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Solution Overview
Problem
Conventional secondary batteries experience electrical disconnection due to deformation of the inversion plate during welding, leading to unreliable current interruption at high temperatures, as the working pressure is compromised by heat-induced deformation.
Innovation Solution
A secondary battery design featuring an external terminal board with a first displacement portion that projects inward and a second displacement portion that interrupts the electrical path, utilizing a load transmission portion and a vulnerable breaking portion to ensure current interruption at a predetermined pressure, without the need for welding the inversion plate, and incorporating an insulating load transmission portion to prevent current flow to the battery case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inversion plate is welded to the collector terminal to secure electric conductivity, then electrical connection is improved, but the inversion plate deforms due to welding heat causing working pressure to deviate from predetermined values
Solution Approach 1:
The patent removes the inversion plate from the electrical conduction path entirely. Instead of welding the inversion plate to the collector terminal, the external terminal board directly contacts the collector terminal through a press-fit mechanism, eliminating the inversion plate's role in electrical conduction and preventing welding-induced deformation.
Solution Approach 2:
The patent separates the mechanical support function and electrical conduction function into distinct components. The inversion plate is removed from the electrical path, and the external terminal board serves both as a mechanical support structure and an electrical conductor, eliminating the conflict between welding requirements and pressure precision.
2Reliability
If the second displacement portion is designed to be easily breakable to interrupt current, then current interruption reliability is improved, but the structure becomes more complex
Solution Approach 1:
The patent uses a thin, flexible second displacement portion with a vulnerable breaking portion that can easily deform and break under pressure. This thin-film structure provides reliable current interruption while maintaining simplicity, as the breaking action is achieved through the inherent flexibility and thinness of the displacement portion rather than complex mechanical mechanisms.
Solution Approach 2:
The second displacement portion is designed to transition from a rigid, conductive state to a broken, insulating state dynamically in response to pressure changes. This dynamic behavior provides reliable current interruption without requiring complex control mechanisms, as the breaking action occurs automatically when the vulnerable portion reaches its breaking point.
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 solution ensures reliable current interruption at the designed working pressure, preventing electrical disconnection and allowing for easy restart of electric conduction, while maintaining the structural integrity of the battery and facilitating downsizing of the current interruption mechanism.
Implementation Method 1
When a temperature inside the secondary battery becomes high and a gas pressure inside the battery case increases, the first displacement portion is pressed due to the gas pressure so as to project toward the external terminal board
Implementation Method 2
The second displacement portion breaks due to a pushing-up force of the load transmission portion. The breakage interrupts the electrical path of the external terminal board, so that no current flows into the external terminal board
Data Source
AI summary
When a temperature inside a secondary battery becomes high and a gas pressure inside a battery case increases, an inversion plate is pressed due to the gas pressure so as to project and curve in a projecting manner toward an external terminal board. Due to such a deformation, a load is transmitted to a current interruption piece via a load transmission portion. At this time, due to a pushing-up force of the load transmission portion, a vulnerable breaking portion forming part of a peripheral edge of the current interruption piece breaks, so that the current interruption piece is displaced to bend in a V-shape via a folding portion. As a result, the secondary battery is brought into an unusable state. Such a configuration can attain simplification of a structure to interrupt a current.