Lithium deposition-guided pore stabilization in bioprotein separators: Insights from synchrotron radiation ultra-small angle X-ray scattering evidence

Bioproteins have been demonstrated as effective modifiers for lithium anode interfaces due to their abundant functional group structures and porous architectures with high specific surface areas. However, the relationship between the evolution of pore structure and lithium ions (Li + ) transport during battery cycling remains unclear. In this study, we propose that the abundant functional group sites on the protein surface can interact with the pores to homogenize the deposition of Li + ， while the uniform deposition of Li + is synergistically coupled with the stabilization of the porous structure through this reorganization process. To investigate the structural evolution of the separator's pore architecture during cycling, we integrated a silk fibroin (SF) network with commercial PP separators and performed ex situ characterization using synchrotron radiation ultra small angle X-ray scattering (SR-USAXS) at different cycling intervals. The results indicate that the integrity of the pore structure remains uncompromised, correlating with effective suppression of lithium dendrite growth. SR-USAXS analysis further reveals the underlying mechanism: the SF-modified layer undergoes a subtle, electrochemically induced structural reorganization. This process leads to a stabilization of the nanoporous framework, which is essential for maintaining uniform ion transport. This work highlights the critical role of protein-modified porous architectures in electrolyte modification and cycling stability for lithium metal batteries, while providing insights for developing bioprotein-based electrolyte separators. • Bioprotein's functional groups and pores homogenize Li + flow, inhibiting dendrites. • Homogeneous Li deposition contributes to separator pore structure stability. • SR-USAXS reveals the intrinsic structural evolution of SF separators.