Metal-Air Cathode Assembly with Sealed Margins
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Solution Overview
Problem
Existing metal/air electrochemical cells face challenges in achieving efficient current collection and minimizing electrolyte leakage, leading to reduced performance and lifespan due to high resistance and electrolyte seepage issues.
Innovation Solution
A process for manufacturing a cathode assembly with a perforated current collector and a conductive metal frame, where the central region is loaded with active electrode particles and a hydrophobic porous film is applied, allowing for reduced resistance and enhanced current extraction, and a sealant is used to minimize electrolyte leakage by forming a cohesive barrier around the catalytically active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electrode material is loaded onto the entire surface of the metallic support including edges, then the current collection area is maximized, but the electrode cannot be electronically welded to enhance current collection
Solution Approach 1:
The patent applies different properties to different regions of the electrode: the central region contains active electrode material for electrochemical reactions, while the peripheral region is kept free of active material to enable electronic welding. This local differentiation allows the electrode to simultaneously achieve effective current collection from the active region and electrical connection through welding at the peripheral region.
2Ease of manufacture
If the peripheral region of the current collector is left free of active material, then electronic welding is enabled for enhanced current collection, but the active electrode material area is reduced
Solution Approach 1:
The electrode is segmented into distinct functional zones: a central active region containing electrode material for electrochemical reactions and a peripheral inactive region for electrical connections. This segmentation allows each zone to optimize its specific function without compromising the other, enabling both effective current collection and welding capability.
3Reliability
If the hydrophobic porous film is applied over the entire electrode surface, then electrolyte impermeability is achieved, but electrolyte leakage occurs at the edges
Solution Approach 1:
The hydrophobic porous film is applied selectively to specific regions of the electrode surface rather than uniformly across the entire surface. This local application strategy ensures electrolyte containment at critical areas while avoiding interference with edge regions where electrolyte leakage was previously problematic, allowing the film to perform its function without creating new leakage paths.
4Power
If the active electrode material extends to the edges of the metallic support, then the electrochemically active area is maximized, but the electrode can only be welded on two sides
Solution Approach 1:
The electrode structure is divided into an active central region and an inactive peripheral region. This segmentation confines the active electrode material to the central area, keeping the edges free for welding connections. The result is an electrode that maintains substantial electrochemically active area while enabling versatile electrical connections at multiple sides through the inactive peripheral region.
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 solution results in improved current collection efficiency with reduced voltage drop and minimized electrolyte leakage, leading to stable and prolonged performance of metal/air electrochemical cells.
Implementation Method 1
hydrophobic porous film (PTFE, Teflon®) supported on one face of said screen or foil. The two opposing faces of the air cathode are exposed to the atmosphere and the alkaline electrolyte, respectively. The air cathode is permeable to air, while its external face is hydrophobic and impermeable to the aqueous electrolyte.
Implementation Method 2
a sealant is used to minimize electrolyte leakage by forming a cohesive barrier around the catalytically active layer
Implementation Method 3
a sealant is used to minimize electrolyte leakage by forming a cohesive barrier around the catalytically active layer
Implementation Method 4
active electrode particles provided within the current collector (including a catalyst for promoting the reduction of oxygen)
Implementation Method 5
sintering the resultant electrode assembly
Data Source
AI summary
The invention provides electrodes suitable for use as air electrodes, processes for their preparation and metal/air cells utilizing such electrodes as air cathodes. The invention relates to an electrode comprising a catalytically active layer applied on one face of a hydrophobic porous film and a conductive current collector pressed onto said catalytically active face, wherein at least a portion of the marginal area of said face is free from catalyst, and wherein a sealant is provided around at least part of the perimeter of said catalytically active layer, said sealant forming a coating onto the catalyst-free marginal area of said hydrophobic film.