Secondary Battery Terminal Resin Layer Peeling Strength
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Solution Overview
Problem
Existing secondary batteries with laminated film exterior bodies face challenges in achieving high reliability due to low peeling strength between the terminal and the exterior body, which can lead to premature failure under internal pressure.
Innovation Solution
The battery design incorporates a resin layer with an internal extension portion that extends from the held portion to the inside of the exterior body, forming a cohesive seal that enhances peeling strength and prevents corrosion of the nickel plane by using an anticorrosive layer only on the internal surfaces, reducing exposure to the electrolyte solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heat-seal resin layer is formed on the terminal surface to seal the held portion, then the sealing function is improved, but the peeling strength between terminal and exterior body is insufficient under internal pressure
Solution Approach 1:
The patent applies composite materials by forming a multi-layer structure on the terminal surface consisting of a nickel layer, an anticorrosive layer, and a heat-seal resin layer. This composite structure combines the corrosion resistance of nickel, the protective function of the anticorrosive layer, and the sealing capability of the heat-seal resin layer, thereby improving both sealing function and peeling strength simultaneously
Solution Approach 2:
The patent applies preliminary action by pre-forming the anticorrosive layer on the nickel layer surface before applying the heat-seal resin layer. This preliminary protective layer prevents corrosion of the nickel layer during subsequent manufacturing processes and ensures the nickel layer maintains its integrity and bonding strength when the heat-seal resin is applied and cured
2Reliability
If an anticorrosive layer is formed to cover the nickel layer surface, then corrosion prevention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies self-service by utilizing the terminal's own nickel layer as the base for forming the anticorrosive layer. The nickel layer serves dual purposes: as the conductive terminal material and as the substrate for the anticorrosive coating, eliminating the need for separate corrosion-resistant substrate preparation and reducing manufacturing complexity
Solution Approach 2:
The patent applies local quality by forming the anticorrosive layer selectively on portions of the nickel layer that require corrosion protection, such as the held portion and exposed surfaces, while maintaining the nickel layer's electrical conductivity in other areas. This localized approach optimizes corrosion resistance without unnecessarily increasing manufacturing complexity across the entire terminal structure
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 significantly improves the peeling strength and reduces nickel plane deterioration, ensuring higher reliability and longer battery life by shifting the failure point from interface peeling to cohesive failure, while maintaining volume efficiency.
Implementation Method 1
a heat-seal resin layer is formed in advance in the portion where the terminal surface (nickel layer surface) is held. Through the resin layer, the terminal is held by the exterior body. The held portion is then heat-sealed.
Implementation Method 2
an anticorrosive layer is formed to cover the surface of the nickel layer in the terminal, which will be in contact with the electrolyte solution in the exterior body, for preventing the corrosion, the elusion, and the like due to the contact with the electrolyte solution.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A secondary battery (1) has a flat shape and houses a power generation element (4) together with an electrolyte solution inside an exterior body (5). A terminal (2, 3) includes: a terminal main body (30) including a nickel plane (31) containing nickel on at least a surface thereof; an anticorrosive layer (32) covering at least a part of the nickel plane (31) that is more on the inside of the exterior body (5) than a held portion (33c); and a resin layer (33) covering at least the held portion (33c) of a surface of the anticorrosive layer (32) and having an internal extension portion (33a) extending from the held portion (33c) to the inside of the exterior body (5).