Fuel Cell Separator with Hexagonal Metal Lath Collector
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Solution Overview
Problem
Conventional separators for polymer electrolyte fuel cells face inefficiencies in gas supply to electrode layers while being effective in electricity collection, leading to imbalanced gas supply and electricity generation efficiency, and are costly due to the use of porous metals.
Innovation Solution
A separator comprising a flat-sheet-like separator body and a collector formed from a metal lath with hexagonal or pentagonal through holes in a meshy, step-like arrangement, allowing efficient gas supply and electricity collection by optimizing contact areas and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional separators with streaky recesses and projections are used, then electricity collection efficiency is improved, but gas supply efficiency deteriorates
Solution Approach 1:
The separator surface is segmented into numerous small contact portions (protrusions) rather than large continuous areas. This segmentation allows gas to access electrode layers through multiple pathways while maintaining sufficient contact points for electricity collection, resolving the contradiction between gas supply and electricity collection efficiency.
Solution Approach 2:
Different regions of the separator have different functions: protrusion portions provide gas supply pathways with small contact areas to electrode layers, while ridge portions provide structural support and electricity collection. This local differentiation allows simultaneous optimization of gas supply and electricity collection in different areas.
2Quantity of substance
If porous metals are used for separators, then gas supply efficiency is improved, but manufacturing cost increases
Solution Approach 1:
The invention uses a metal sheet with controlled surface topology (ridges and valleys) instead of porous metals. The non-porous metal sheet with engineered surface features provides gas flow pathways while avoiding the high manufacturing costs and potential reliability issues associated with porous metal materials.
Solution Approach 2:
The invention replaces the porous structure mechanism with a surface topology mechanism. Instead of relying on porous pathways for gas flow, the design uses raised ridges and valleys created by mechanical forming processes, which are more cost-effective and manufacturable.
3Productivity
If protruding pieces are used to form gas passageway, then gas diffusion efficiency is improved, but contact area with electrode layer is reduced
Solution Approach 1:
The separator contact surface is divided into numerous small protrusion portions distributed across the surface. Each protrusion provides a localized gas supply pathway and contact point, collectively providing both efficient gas diffusion and sufficient total contact area for electricity collection.
Solution Approach 2:
The gas passageway is formed by creating three-dimensional surface topology (ridges and valleys) on the separator surface rather than relying solely on two-dimensional contact area reduction. This dimensional approach allows gas flow pathways to be established without proportionally reducing the functional contact area.
Data Source
AI summary
A separator includes a separator body 11 and a collector 12. The separator body 11 prevents a mixed flow of fuel gas and oxidizer gas. The collector 12 is formed from a metal lath RM in which through holes each having an opening shape assuming the form of a hexagon are formed in a meshy, step-like arrangement. This establishes a substantially linear contact mode between the collector 12 and each of the separator body 11 and a carbon cloth CC superposed on an MEA 30. This contact mode increases a contact area between the carbon cloth CC and gas and allows a necessary and sufficient contact area between the carbon cloth CC and the separator body 11. Thus, gas can be supplied efficiently, and generated electricity can be collected efficiently to thereby improve electricity generation efficiency of a fuel cell.