Thin Metal Foil Cell Packaging With Narrow Hermetic Laser Welds
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Solution Overview
Problem
Conventional pouch battery packaging for small electrochemical cells is inefficient due to thickness, wide seals, and limited hermeticity, which restricts energy density and performance.
Innovation Solution
Employ thin metal foil packaging that serves as both a hermetic seal and current collector, using laser welding to create narrow, hermetic metal-to-metal seals close to the electrochemical stack, eliminating thermoplastic sealants and optimizing seal width and proximity to the cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pouch packaging with thermoplastic sealants is used, then ease of manufacture is improved, but hermeticity deteriorates
Solution Approach 1:
The patent changes the sealing method from thermoplastic bonding to metal-to-metal welding, fundamentally altering the sealing mechanism to achieve superior hermeticity while maintaining manufacturability through established welding processes
Solution Approach 2:
The patent employs a composite structure combining metal foil layers with electrode materials, where the metal foil serves dual functions as both packaging and hermetic seal, eliminating the need for separate thermoplastic sealant layers
2Reliability
If wide seals are used in pouch packaging, then reliability of seal is improved, but volume efficiency deteriorates
Solution Approach 1:
The patent changes the seal width parameter from conventional wide seals (typically several millimeters) to narrow metal-to-metal welds (less than 1 millimeter), achieving sufficient reliability through the inherent strength and hermeticity of metal welding
Solution Approach 2:
The patent uses thin metal foil packaging that can be efficiently sealed with narrow welds, leveraging the properties of thin metal films to achieve both reliability and volume efficiency
3Strength
If thick pouch packaging is used, then mechanical strength is improved, but energy density deteriorates
Solution Approach 1:
The patent employs thin metal foil packaging that provides sufficient mechanical strength and hermetic protection while minimizing thickness, thereby maximizing the volume available for active materials and improving energy density
Solution Approach 2:
The metal foil packaging serves multiple functions simultaneously: structural support, hermetic seal, and current collector, eliminating the need for separate thick protective layers and sealant layers
4Ease of manufacture
If seals are placed far from electrochemical stack, then manufacturing ease is improved, but hermeticity deteriorates
Solution Approach 1:
The patent changes the seal proximity parameter, placing the metal-to-metal welds in close proximity to the electrochemical stack, which improves hermeticity by minimizing the distance over which contaminants could penetrate while remaining compatible with manufacturing processes
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
Achieves high energy capacity and efficiency with cell thickness less than 1 millimeter, improving hermeticity and reducing volume occupied by seals, thereby enhancing energy storage performance.
Implementation Method 1
The laser welds the edges of the metal foil to one another
Data Source
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AI summary
An electrochemical cell is provided comprising a thin metal foil packaging made from at least one sheet of metal foil and having a perimeter extending around at least a portion of the electrochemical cell, as well as an electrochemical cell stack contained within the thin metal foil packaging, and a metal-to-metal welded seal around at least a portion of the perimeter of the thin metal foil packaging. The metal-to-metal welded seal is hermetic or nearly hermetic. Furthermore, the metal-to-metal welded seal is narrow, having a width of less than about 1 mm, and is less than about 5 mm away from the electrochemical cell stack. In some embodiments, the thin metal foil packaging functions not only as a hermetically or near hermetically sealed packaging, but also as either the negative or positive current collector, with one electrode of the cell bonded to the foil packaging. A method for making the foregoing electrochemical cell is also provided and involves using laser energy the metal-to-metal welded seal, wherein the laser energy is applied to the foil at high speed using a scanning laser.