Fabrication of ultrathin Fe-metal organic framework-derived Fe3O4 all solid state battery: Developing test platform for probing the solid electrolyte/electrode interface

The integration of iron-based metal–organic frameworks (Fe-MOFs) with Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) as a solid electrolyte offers a promising pathway toward high-performance, all-solid-state batteries (ASSBs) with enhanced safety and stability. In this study, we report on the fabrication and characterization of an ultrathin Fe-MOF anode interfaced with LATP, leveraging the benefits of electrophoretic deposition (EPD) to create an additive-free and well-controlled thin layer. This architecture allows for direct analysis of the solid electrolyte/electrode interface, eliminating bulk electrode effects and enabling focused investigations of interfacial phenomena critical to ASSB performance. The dominance of diffusion-controlled behavior with a b value of 0.5 with a diffusion coefficient of 3.9 × 10⁻¹³ cm²/s arises from the intrinsic bulk redox activity of Fe₃O₄, the porous nature of the deposited film enabling effective ionic diffusion, and the strong interface with the LATP electrolyte, which facilitates ion transport into the bulk. This work not only highlights the potential of Fe-MOF and LATP in ASSB applications but also establishes an experimental platform for exploring and optimizing solid-state battery interfaces.