Pouch Battery Separator Structure for Overcharge Short-Circuit Protection
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Solution Overview
Problem
Secondary batteries are at risk of ignition and explosion due to overcharging, and existing solutions do not effectively prevent overcharging.
Innovation Solution
The secondary battery design includes a separator system where the positive and negative electrodes are short-circuited when the pouch swells due to gas generation during overcharging, causing an internal short circuit and interrupting power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is used to prevent short circuit between electrodes, then battery safety is improved, but the separator may prevent effective overcharge interruption when pouch swells
Solution Approach 1:
The separator is designed with a through-hole that dynamically changes its blocking function based on pouch expansion. When the pouch is in normal state, the through-hole is blocked by the second separator maintaining electrical insulation. When the pouch swells due to overcharging, the second separator moves and the through-hole opens, creating a short circuit to interrupt overcharge. This dynamic behavior allows the separator to adapt its function based on battery condition.
Solution Approach 2:
The second separator acts as an intermediary element that mediates between the pouch expansion and the through-hole opening. It is disposed to cover the through-hole and is connected to the pouch, so it translates pouch swelling into mechanical movement that opens or closes the electrical pathway. This intermediary mechanism enables indirect control of the short circuit condition through pouch expansion.
2Difficulty of detecting and measuring
If the pouch is made swellable to detect overcharge, then overcharge detection capability is improved, but gas generation and pouch swelling create safety hazards
Solution Approach 1:
The invention converts the harmful effect of gas generation and pouch swelling into a beneficial detection mechanism. Instead of preventing pouch swelling, the design utilizes it as the triggering condition for overcharge protection. When gas generates and the pouch swells during overcharge, this movement opens the through-hole to create a short circuit, transforming the harmful swelling into a useful safety signal.
Solution Approach 2:
The battery system uses its own overcharge condition (gas generation and pouch swelling) to automatically trigger the protection mechanism without external sensors or control systems. The pouch expansion itself serves as the detection and activation mechanism, making the system self-diagnosing and self-protecting.
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 design effectively interrupts overcharging by creating an internal short circuit when the battery is overcharged, preventing potential ignition and explosion while ensuring safety within an allowable range.
Implementation Method 1
when the pouch is swelled by the generation of the gas
Data Source
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AI summary
The present invention relates to a secondary battery. The secondary battery according to the present invention comprises an electrode assembly in which a positive electrode, a separator, and a negative electrode are alternately combined to be laminated; and a pouch accommodating the electrode assembly therein, wherein the separator comprises a first separator disposed between the positive electrode and the negative electrode and having a through-hole penetrated in a direction facing the positive electrode and the negative electrode and a second separator covering the through-hole of the first separator and having an end connected to the pouch, wherein, when an internal gas is generated due to overcharging, the pouch is expanded to allow the second separator to move so as to open the through-hole of the first separator so that the positive electrode and the negative electrode contact each other through the through-hole.