Microporous Metal Foil Pore Formation via Pattern Roll Pressing
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Solution Overview
Problem
Existing methods for producing microporous metal foils, such as those used in lithium-ion batteries and capacitors, face challenges in achieving high energy density due to small pore diameters and low productivity, leading to high costs and inadequate mechanical strength.
Innovation Solution
A method involving passing a metal foil through a gap between a pattern roll with high-hardness fine particles and a hard roll, with a thin hard plastic film between the foil and the pattern roll and a thick soft plastic film between the foil and the hard roll, to form fine penetrating pores without breaking the foil, and adjusting tensions to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If DC electrolytic etching is used to form penetrating pores, then pores are formed in the metal foil, but the pore diameter is small (0.2-5 μm) and productivity is low
Solution Approach 1:
The patent replaces the electrochemical etching process with a mechanical punching method. A punching roll with protrusions presses against the metal foil to physically punch through and create pores, substituting chemical/electrochemical processes with a mechanical system that achieves both larger pore diameters and higher productivity
Solution Approach 2:
The patent changes the pore formation mechanism from electrochemical dissolution to mechanical displacement. By controlling the punching roll parameters (protrusion shape, size, arrangement) and pressing force, the pore diameter can be adjusted to 5-50 μm, significantly larger than etching pores, while the mechanical process enables continuous high-speed production
2Productivity
If punching is performed without plastic films, then pores are formed efficiently, but the metal foil breaks due to direct contact with high-hardness particles
Solution Approach 1:
The patent introduces plastic films as intermediary layers between the punching roll and metal foil. The first plastic film (with protrusions) transfers the punching force, while the second plastic film (without protrusions) provides cushioning and prevents direct contact between high-hardness particles and the foil, avoiding breakage while maintaining pore formation efficiency
Solution Approach 2:
The patent applies cushioning in advance by placing the second plastic film between the punching roll and metal foil before the punching process. This cushioning layer absorbs excessive force and prevents direct impact of high-hardness particles on the foil, ensuring foil integrity during efficient pore formation
3Quantity of substance
If pore diameter is increased to hold more active material, then energy density increases, but mechanical strength of the foil decreases
Solution Approach 1:
The patent uses plastic films as flexible intermediaries that allow large pore formation without compromising foil strength. The films deform during punching and recover, enabling the creation of large pores (5-50 μm) that can hold sufficient active material while the surrounding metal matrix maintains structural integrity
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 approach efficiently produces microporous metal foils with high opening ratios and mechanical strength, suitable for holding active materials in energy storage devices, while reducing production costs.
Implementation Method 1
passing a metal foil through a gap between a pattern roll having large numbers of high-hardness, fine particles on the surface and a hard roll while pressing
Implementation Method 2
pressing, to provide said metal foil with large numbers of fine penetrating pores
Data Source
Figure 1
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AI summary
A method and an apparatus for producing a microporous metal foil comprising (a) passing a metal foil through a gap between a pattern roll having large numbers of high-hardness, fine particles on the surface and a hard roll while pressing, to provide the metal foil with large numbers of fine penetrating pores, with a thin hard plastic film interposed between the metal foil and the pattern roll, and a thick soft plastic film interposed between the metal foil and the hard roll; and (b) adjusting tension applied to each of the metal foil, the hard plastic film and the soft plastic film to such an equal level that the metal foil is not broken during forming the fine penetrating pores.