Battery Module Short-Circuit Structure for Preemptive Overcharge Protection
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Solution Overview
Problem
Existing overcharge prevention mechanisms in secondary batteries, such as PTC and TCO, operate after heat generation, leading to delayed current blocking and potential early activation in high current environments like vehicle battery packs, necessitating a solution that can preemptively prevent overvoltage by generating a short circuit before temperature rise.
Innovation Solution
A battery module with a short circuit inducing member, comprising an electroactive polymer (EAP) layer and metal layers, that deforms to create a short circuit between battery cells when a potential difference exceeds a reference value, consuming current and preventing overvoltage, and optionally includes PTC elements to manage short circuit current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal fuse, PTC, or TCO is used for overcharge prevention, then current blocking function is provided, but the resistance increases after repeated operation and the operation is delayed until heat generation occurs
Solution Approach 1:
The electroactive polymer layer is positioned to make contact with the electrode lead in advance before overcharge occurs. When overvoltage is detected, the polymer layer immediately deforms to create a short circuit, eliminating the time delay associated with thermal response mechanisms.
Solution Approach 2:
The patent replaces thermal-based mechanical systems (PTC, TCO, thermal fuse) with an electroactive polymer system that responds to voltage changes through electrochemical deformation, enabling faster response without heat generation delay.
2Duration of action of stationary object
If PTC or TCO is used for repeated overcharge prevention, then reusable current blocking is achieved, but the resistance increases with repeated operation
Solution Approach 1:
The electroactive polymer layer can be restored to its original state after deformation by reversing the voltage polarity or removing the voltage stimulus, allowing it to be reused without accumulating resistance, unlike PTC or TCO materials.
3Reliability
If thermal-based overcharge prevention elements are used in high current battery packs, then overcharge protection is provided, but the elements activate too early due to high temperature environment
Solution Approach 1:
The patent changes the triggering parameter from temperature-based (thermal elements) to voltage-based (electroactive polymer). This allows the protection mechanism to operate independently of the ambient temperature, making it suitable for high current battery packs where early thermal activation would be problematic.
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 effectively prevents overvoltage by reversibly generating a short circuit before temperature increase, ensuring safety in secondary batteries by consuming current proactively, and the PTC elements further prevent overheating risks.
Implementation Method 1
A battery module with a short circuit inducing member, comprising an electroactive polymer (EAP) layer and metal layers, that deforms to create a short circuit between battery cells when a potential difference exceeds a reference value
Data Source
AI summary
A battery module includes a first battery cell and a second battery cell respectively having a positive electrode lead and a negative electrode lead and connected to each other in series; and a short circuit inducing member having one longitudinal side interposed between the negative electrode lead of the first battery cell and the positive electrode lead of the second battery cell and the other longitudinal side located between the positive electrode lead of the first battery cell and the negative electrode lead of the second battery cell. When a potential difference between the negative electrode lead of the first battery cell and the positive electrode lead of the second battery cell increases over a reference value, the other longitudinal side of the short circuit inducing member makes flexural deformation toward the negative electrode lead of the second battery cell to come into contact with the negative electrode lead.