Probing Solid-State Interface Kinetics via Alternating Current Electrophoretic Deposition: LiFePO4 Li-Metal Batteries

초록

This work presents a comprehensive investigation into the interfacial charge storage mechanisms and lithium-ion transport behavior of Li-metal all-solid-state batteries (ASSBs) employing LiFePO4 (LFP) cathodes fabricated via alternating current electrophoretic deposition (AC-EPD) and Li1.3Al0.3Ti1.7(PO4)(3) (LATP) as the solid-state electrolyte. We demonstrate that optimal sintering improves the LATP-LFP interfacial contact, leading to higher lithium diffusivity (similar to 10(-9) cm(2)center dot s(-1)) and diffusion-controlled kinetics (b approximate to 0.5), which directly translate to better rate capability. Structural and electrochemical analyses-including X-ray diffraction, scanning electron microscopy, cyclic voltammetry, and rate capability tests-demonstrate that the cell with LATP sintered at 900 degrees C delivers the highest Li-ion diffusivity (similar to 10(-9) cm(2)center dot s(-1)), near-ideal diffusion-controlled behavior (b-values similar to 0.5), and superior rate capability. In contrast, excessive sintering at 1000 degrees C led to reduced diffusivity (similar to 10(-10) cm(2)center dot s(-1)). The liquid electrolyte system showed higher b-values (similar to 0.58), indicating the inclusion of surface capacitive behavior. The correlation between b-values, diffusivity, and morphology underscores the critical role of interface engineering and electrolyte processing in determining the performance of solid-state batteries. This study establishes AC-EPD as a viable and scalable method for fabricating additive-free LFP cathodes and offers new insights into the structure-property relationships governing the interfacial transport in ASSBs.

키워드