Perforation-driven micropore engineering for high-rate and stable SiOx anodes

As demand rises for fast-charging and high-energy lithium-ion batteries, thick SiO_x-based anodes still face slow ion transport and mechanical degradation. Researchers led by Prof. Hongkyung Lee and Prof. Yong Min Lee now report a scalable solution based on a perforated Cu (pCu) current collector, which induces a regularly arranged micropore (RAM) structure. This simple yet powerful design enhances ion diffusion, mechanical stability, and overall electrochemical performance in SiO_x/artificial graphite (AG) electrodes.

Why Micropore Regulation Matters

• Transport bottleneck: Thick SiO_x/AG electrodes suffer from tortuous Li-ion pathways and concentration polarization, which limit rate capability.
• Mechanical degradation: SiO_x experiences large volume change, causing cracking, delamination, and rapid capacity loss.
• Scalability gap: Existing pore-engineering approaches (laser patterning, additives) add complexity; a simple, compatible method is needed for industrial use.

Design Concept: Perforated Cu Induces RAM

• Perforation mechanism: Chemical etching produces microscale holes in Cu foil. When slurry is cast and calendered, holes fill with active material, producing alternating high-porosity domains (HPds) above perforations and low-porosity domains (LPds) elsewhere.
• Interface chemistry and mechanics: Etching creates hydroxyl-rich Cu surfaces that enhance wetting and hydrogen-bonding with PAA binder, while the filled holes form an interlocking interface that resists delamination.

Transport Dynamics & Electrochemical Advantages

• Faster, more uniform ion flux: Microstructure-resolved segmentation and pore-network analysis show larger equivalent pore radii, higher coordination numbers, and lower tortuosity in HPds—facilitating rapid Li-ion access and more homogeneous ion distribution.
• Reduced polarization at high rates: Pseudo-4D electrochemical simulations show lower overpotential and deeper utilization during fast discharge (e.g., 3C), consistent with experiments.
• HPd–LPd synergy: HPds act as local ion reservoirs, improving ion supply to adjacent LPds and mitigating localized depletion.

Performance Highlights

• Rate capability: RAM electrodes deliver higher capacities across 0.2C–5C and recover well when returned to low C-rates.
• Durability: Slower growth of interfacial resistance, smaller irreversible thickness changes, and minimal delamination yield markedly improved cycle life.
• Scalability: Double-sided pCu electrodes and 60-mAh pouch cells confirm manufacturing viability.

Practical Benefits & Outlook

• Energy-density gain: Perforation reduces Cu mass (~32%), raising gravimetric energy density to ~258 Wh kg^-1 and volumetric to ~694 Wh L^-1.
• Manufacturing-ready: pCu retains sufficient tensile strength for roll-to-roll processing. Future work should optimize perforation geometry and extend the RAM concept to higher-Si formulations.

This simple, low-cost modification of the current collector provides a practical route to fast-charging, long-life SiO_x anodes and advances scalable battery electrode engineering.