Pouch Battery Electrode Lead Venting Through Thermal Expansion
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Solution Overview
Problem
Lithium ion secondary batteries face issues with thermal runaway and thermal propagation due to increased cell pressure from electrolyte vaporization and chemical reactions, posing safety concerns.
Innovation Solution
A secondary battery design featuring a polymer compound layer on the electrode lead that expands or contracts with temperature changes, creating a vent to release gas and electrolyte before rapid temperature increases occur, thereby preventing thermal runaway and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the battery structure is sealed to maintain integrity, then structural strength is improved, but gas accumulation and thermal runaway risk increase
Solution Approach 1:
The polymer compound layer is pre-applied to the electrode lead before battery assembly. When thermal runaway occurs, this layer automatically expands to create a vent channel, preventing gas accumulation while maintaining structural integrity. The venting action occurs automatically at the appropriate temperature without requiring external intervention.
2Reliability
If the sealing portion is made robust to prevent leakage, then reliability is improved, but gas venting capability deteriorates
Solution Approach 1:
The polymer compound layer acts as an intermediary element between the robust sealing portion and the electrode lead. Under normal conditions, it maintains sealing integrity. When temperature rises, it expands to create a vent channel through the sealing portion, allowing gas to escape without compromising the overall sealing structure.
3Object-affected harmful factors
If the electrode lead is covered completely to prevent exposure, then safety is improved, but thermal response and venting speed decrease
Solution Approach 1:
The polymer compound layer is applied specifically to the sealing portion of the electrode lead rather than covering the entire lead. This localized application provides protection where needed while maintaining thermal responsiveness at the critical sealing interface, enabling rapid venting when temperature rises without excessive coverage slowing the response.
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 polymer compound layer effectively stabilizes the battery by releasing pressure and preventing thermal propagation, maintaining performance and ensuring safety by suppressing thermal runaway and explosions.
Implementation Method 1
A polymer compound layer including a thermally expandable polymer compound or a heat-shrinkable polymer compound may be attached on at least one of an upper surface and a lower surface of an electrode lead
Implementation Method 2
at least one heat-shrinkable polymer compound selected from the group consisting of polyphenylene ether (PPE), polycarbonate (PC), polyoxymethylene (POM) and polyamide (PA)
Data Source
AI summary
A secondary battery includes an electrode assembly to which an electrode lead is bonded, a pouch case including a case body portion accommodating the electrode assembly in such a manner that a portion of the electrode lead protrudes externally, and a cover portion covering the case body portion, and a sealing portion in which the body portion and an outer circumferential portion of the cover portion of the pouch case contact each other and are sealed by thermal fusion. A polymer compound layer is attached on at least one of an upper surface and a lower surface of the electrode lead protruding externally. The polymer compound layer includes a thermally expandable polymer compound of a composite of a hydroxy group-containing compound and silica, or at least one heat-shrinkable polymer compound selected from the group consisting of polyphenylene ether (PPE), polycarbonate (PC), polyoxymethylene (POM) and polyamide (PA) .