Laminated Steel Battery Case Sealing With Welded and Melt-Bonded Joints
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Solution Overview
Problem
Existing battery containers face issues with insufficient sealability leading to degradation due to water vapor penetration, increased production costs and workloads, and reduced service life, especially in laminated type lithium ion batteries, where heat sealing and welding processes are separate and often result in resin deformation and corrosion.
Innovation Solution
A battery case design using a laminated steel sheet with a welded part, a melt bonded part, and a controlled gap part, where the length of the gap part is limited relative to the steel sheet thickness, allowing for integrated welding and heat sealing processes, enhancing sealability and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the length of the heat sealed part is increased to extend service life, then the service life is improved, but the cell volume per unit space decreases
Solution Approach 1:
The patent merges the heat sealing process and welding process into a single integrated operation. The heat sealing unit simultaneously performs heat sealing and welding by coordinating the heating mechanism and pressing mechanism, eliminating the need for separate processing steps. This reduces the total length required for sealing while maintaining both the service life benefits of extended sealing and the space efficiency of compact design.
Solution Approach 2:
The battery case employs a composite structure combining a resin layer and a metal foil layer. The resin layer provides heat sealing capability while the metal foil layer provides welding capability and enhanced barrier properties. This composite material approach allows the sealing structure to achieve both long service life through robust sealing and reduced volume through efficient material utilization.
2Reliability
If heat sealing and welding are performed as separate processes, then the sealability is improved, but the production workload and cost increase
Solution Approach 1:
The patent integrates heat sealing and welding into a single simultaneous process performed by one heat sealing unit. The unit coordinates the heating mechanism and pressing mechanism to execute both functions in one operation, thereby maintaining high sealability while significantly reducing production workload and eliminating the need for separate welding equipment and processes.
Solution Approach 2:
The heat sealing unit is designed with multi-functionality, capable of performing both heat sealing and welding operations. The heating mechanism can adjust its temperature and duration to achieve either heat sealing of the resin layer or welding of the metal foil layer, while the pressing mechanism provides the necessary force for both operations. This universal unit reduces equipment complexity and production costs.
3Reliability
If separate heat sealing and welding processes are used, then the sealability is improved, but the production cost increases
Solution Approach 1:
The patent combines heat sealing and welding into a single integrated process within one heat sealing unit, eliminating the need for separate equipment, tooling, and process control systems. This consolidation maintains the high sealability required for battery reliability while significantly reducing capital equipment costs, operational costs, and manufacturing complexity.
Solution Approach 2:
The heat sealing unit incorporates multi-functional capabilities to perform both heat sealing and welding operations using a single device. The heating mechanism can be controlled to achieve different temperature profiles for resin heat sealing or metal foil welding, and the pressing mechanism adapts to provide appropriate force for each operation type, thereby reducing overall production cost while maintaining seal quality.
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 design achieves improved sealability, longer service life, smaller size, and higher mountability while reducing production costs by integrating welding and heat sealing processes, and mitigating resin deformation and corrosion.
Implementation Method 1
a welded part of the plated steel sheet
Implementation Method 2
a melt bonded part of the film
Data Source
AI summary
A battery case and method of production of the same realizing smaller size, higher mountability, longer service life, and lower cost than in the past, that is, a battery case comprising a container body and a container cover, in which battery case, one or both of the container body and the container cover are made from a laminated steel sheet comprised of a plated steel sheet on which a film having a polyolefin-based resin as a main constituent is laminated, a joined part of the container body and the container cover has a welded part of the plated steel sheet, a melt bonded part of the film, and a gap part between the welded part and the melt bonded part, where a length of gap part/thickness of plated steel sheet ≤10.0 and a length of gap part/length of joined part <0.50, and at least part of the inside surface of the battery case is covered by the film, and a method of production of the same.