- Structural Features
- Gradient Porosity Design: Dense surface (reduces contact resistance) with porous interior (enhances gas diffusion).
- Bio-Inspired Microporous Structures: Mimics alveoli or vascular branching to improve mass transfer efficiency.
- Performance Advantages
- High Conductivity: Combines bulk titanium conductivity with porous structures to lower internal resistance.
- Corrosion Resistance: Stable in pH 2–12 environments, compatible with various electrolytes (PEMFC, AFC, etc.).
- Lightweight: Replaces graphite/stainless steel components, reducing fuel cell system weight by 20%–30%.
- Thermal Management: High thermal conductivity (21.9 W/m·K) aids heat dissipation, preventing localized overheating.
- Functional Expansion Potential
- Surface Modification: Nitriding, carbon coatings, or noble metal deposition further enhance conductivity and catalytic activity.
- Integrated Design: 3D-printed porous titanium can combine GDLs, flow fields, and cooling channels, simplifying stack architecture.
III. Performance Comparison with Traditional Materials
| Material | Porous Titanium | Graphite | Stainless Steel |
| Density (g/cm³) | 2.5–4.5 | 1.8–2.2 | 7.9 |
| Conductivity (S/cm) | 1000–6000 (post-modification) | 100–200 | 1.4×10⁴ (depends on passivation) |
| Corrosion Resistance | Excellent (TiO₂ passivation) | Strong but brittle | Requires coatings; prone to corrosion |
| Processing Cost | High (3D printing), reducible at scale | Low (complex channel machining) | Moderate (needs corrosion coatings) |
IV. Challenges and Future Directions
- Technical Challenges
- Cost: High raw material and 3D printing expenses; requires low-cost powder metallurgy solutions.
- Interface Optimization: Further reduction of contact resistance between porous titanium and catalysts/membranes.
- Water Management: High hydrophobicity may hinder liquid water removal; surface hydrophilicity/hydrophobicity tuning needed.
- Research Focus
- Nanostructured Porous Titanium: Enhances surface area and catalytic activity via nanoscale designs.
- Hybridization: Composites with carbon materials (e.g., graphene) balance conductivity, cost, and corrosion resistance.
- Smart Structures: Develop porosity-tunable titanium for dynamic adaptation to varying operating conditions.