Multilayer Sealing Member for Battery Case
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face degradation in sealing performance due to moisture ingress and impact forces, with butadiene rubber (BR) degrading under chemical reactions and ethylene propylene diene rubber (EPDM) lacking sufficient rebound resilience.
Innovation Solution
A multilayer sealing member structure is introduced, comprising a first layer of butadiene rubber, urethane rubber, silicone rubber, chloroprene rubber, or isoprene rubber for high rebound resilience, and a second layer of ethylene propylene rubber, ethylene propylene diene rubber, or fluoro rubber for high electrolyte-solution resistance, enhancing vibration, dropping, and electrolyte-solution resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member containing EPDM is used to suppress degradation due to contact with electrolyte solution, then chemical resistance is improved, but rebound resilience decreases leading to degraded impact-force resistance
Solution Approach 1:
The sealing member is divided into multiple layers with different material compositions. The first layer contains EPDM (5-50 mass%) to provide chemical resistance against electrolyte solution, while the second layer contains BR (5-50 mass%) to provide high rebound resilience for impact-force resistance. This segmentation allows each layer to specialize in one function without compromising the other.
Solution Approach 2:
The sealing member uses a composite structure combining EPDM and BR in a multilayer configuration. This composite material approach leverages the strengths of both materials: EPDM's chemical inertness and BR's elastic recovery properties, achieving both chemical resistance and impact-force resistance simultaneously.
2Strength
If BR is used as the sealing member main constituent, then rebound resilience and impact-force resistance are improved, but chemical reaction with electrolyte solution causes deterioration
Solution Approach 1:
The sealing member is divided into multiple layers with different material compositions. The first layer contains EPDM (5-50 mass%) to provide chemical resistance against electrolyte solution, while the second layer contains BR (5-50 mass%) to provide high rebound resilience for impact-force resistance. This segmentation allows each layer to specialize in one function without compromising the other.
Solution Approach 2:
The sealing member uses a composite structure combining EPDM and BR in a multilayer configuration. This composite material approach leverages the strengths of both materials: EPDM's chemical inertness and BR's elastic recovery properties, achieving both chemical resistance and impact-force resistance simultaneously.
3Device complexity
If a single-layer sealing member is used, then device complexity is reduced, but it cannot simultaneously provide both high rebound resilience and high chemical resistance
Solution Approach 1:
The sealing member is divided into multiple layers with different material compositions. The first layer contains EPDM (5-50 mass%) to provide chemical resistance against electrolyte solution, while the second layer contains BR (5-50 mass%) to provide high rebound resilience for impact-force resistance. This segmentation allows each layer to specialize in one function without compromising the other.
Solution Approach 2:
The sealing member uses a composite structure combining EPDM and BR in a multilayer configuration. This composite material approach leverages the strengths of both materials: EPDM's chemical inertness and BR's elastic recovery properties, achieving both chemical resistance and impact-force resistance simultaneously.
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 multilayer sealing member structure maintains sealing performance under high temperatures and impact forces, preventing moisture ingress and prolonging battery life by combining high rebound resilience with chemical resistance.
Implementation Method 1
EPDM has lower rebound resilience than BR, and thus, when an impact force applied to a battery due to, for example, vibration or dropping deforms a gasket and the sealing member, sealing performance may be degraded
Implementation Method 2
EPDM has lower rebound resilience than BR, and thus, when an impact force applied to a battery due to, for example, vibration or dropping deforms a gasket and the sealing member, sealing performance may be degraded. In other words, there is room for improvement in impact-force resistance of a battery including a sealing member containing EPDM
Data Source
AI summary
An object of the present disclosure is to provide a high-endurance and long-life nonaqueous electrolyte secondary battery including a battery case having sealing performance unlikely to be degraded. A nonaqueous electrolyte secondary battery according to an aspect of the present disclosure includes a closed-end cylindrical outer can, a sealing body that closes an opening of the outer can, a resin gasket disposed between the outer can and the sealing body, a sealing member interposed between the outer can and the gasket, and a nonaqueous electrolyte. The sealing member has a multilayer structure including a first sealing member layer, the main constituent of which is one selected from butadiene rubber, urethane rubber, silicone rubber, chloroprene rubber, and isoprene rubber, and a second sealing member layer, the main constituent of which is one selected from ethylene propylene rubber, ethylene propylene diene rubber, and fluoro rubber.