Ac-Electrophoretic deposition fabricated LiFePO4 composite cathodes with enhanced diffusion-controlled charge storage for solid-state lithium metal batteries

Abstract

In this study, we report the fabrication and electrochemical analysis of an all-solid-state lithium (Li) metal battery comprising a Li metal anode, a Li₁.₃Al₀.₃Ti₁.₇(PO₄)₃ (LATP) solid electrolyte, and a LiFePO₄ (LFP) cathode deposited via alternating current electrophoretic deposition (AC-EPD) with conductive and structural additives. The use of AC-EPD enables the formation of a uniform, compositionally controlled LFP composite cathode with intimate contact to the solid electrolyte layer. Through a combination of cyclic voltammetry, galvanostatic charge/discharge, we confirm that the charge storage mechanism is predominantly diffusion-controlled with b values of 0.53 (oxidation) and 0.52 (reduction) with a diffusion coefficient of 4.68 × 10⁻¹⁰ cm²/Vs, highlighting the exceptional rate capability and cycle stability. The inclusion of additives facilitates improved electronic conductivity and mechanical integrity of the cathode, enabling stable cycling within the all-solid-state configuration. This work demonstrates the viability of using AC-EPD as a scalable route for fabricating high-quality composite cathodes and provides valuable insight into interfacial transport processes critical for the development of high-performance, solid-state lithium metal batteries.