Chemical Etching of Nanoporous Al Foil for Enhancing the Stability of LiFeMnPO ₄ Cathodes

This work addresses critical interfacial instability in lithium manganese iron phosphate (LMFP) cathodes by developing a nanoporous aluminum current collector (NP-Al) via controlled chemical etching. Characterization reveals a uniform 50-nm pore architecture (SEM/AFM) that enhances surface roughness by 210% and forms a protective Al₂O₃ layer (XPS), while preserving bulk conductivity (XRD). Electrochemical validation demonstrates that NP-Al significantly outperforms conventional Al foil: LMFP/NP-Al achieves 84% capacity retention after 300 cycles at 1C (vs. 66% for LMFP/Al) and triples peel strength (1.28 vs. 0.42 kN/m). These performance improvements are correlated with three synergistic effects: (1) mechanical interlocking potentially mitigating active material delamination, (2) 35% lower charge transfer resistance (EIS: 206.6 Ω vs. 318.1 Ω) supporting 415% higher capacity at 10 C, and (3) electrolyte-wetting optimization (contact angle: 31.9° vs. 46.4° in NMP). These innovations mitigate the interplay between adhesion and degradation in high-energy cathodes, positioning nanoporous collectors as promising enablers for durable lithium-ion batteries.