Utilizing Li Metal Anode with High Ionic Conductivity for Enhancing Interfacial Stability in LATP-Based Solid-State Batteries

All-solid-state lithium metal batteries attract attentions because of their high energy density and enhanced stability. However, the practical application of lithium metal remains challenging due to dendrite growth and limited coulombic efficiency. In this study, we designed a composite anode by incorporating a Li₃N-LiF composite electrolyte into a lithium metal electrode to secure a pathway for lithium-ion transport and extend localized interfacial reduction reactions. Li₃N-LiF incorporated lithium metal foil was prepared via dry ball-milling of Li₃N-LiF powders with Li metal granules, followed by melting the mixture and roll-pressing it into a foil form. The symmetric and full cells were prepared by coating protective layers (PL) on both sides of the LATP(Li1.3Al0.3Ti1.7(PO4)3) electrolyte to prevent the side reaction between solid electrolyte and electrodes. The symmetric cells comprised Li (or Li+Li₃N-LiF) /PL/LATP/PL/Li (or Li+Li₃N-LiF), and the full cells comprised Li (or Li+Li₃N-LiF)/PL/LATP/PL/LFP(LiFePO4). The symmetric cell utilizing Li+Li₃N-LiF foil exhibited a reduced overvoltage of 800 mV at 0.8mA/cm², compared to the Li foil symmetric cell, over 100 hours. Moreover, the Li+Li₃N-LiF foil symmetric cell was stably discharged-charged for 1000 hours without voltage noise (short circuit formation signal). The full cell exhibited a higher capacity retention (~90% for 200 cycles) than Li metal full cells (~73% for 160 cycles) at 0.2mA/cm². Therefore, the modification of the Li₃N-LiF composite anode was effective for enhancing cycling performance in all-solid-state Li metal batteries.