Stabilizing Li1.3Al0.3Ti1.7(PO4)3|Li Metal Anode Interface in Solid-State Batteries by Kevlar Aramid Nanofiber-Based Protective Coating

Abstract

Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid-state electrolyte has garnered considerable interest owing to its competitive room-temperature Li-ion conductivity, air stability, and economic nature. Nevertheless, the successful implementation of LATP in next-generation Li-metal solid-state batteries (SSBs) is impeded by its high incompatibility with Li metal. Herein, combining the Kevlar aramid nanofiber (KANF) membrane with a solidified electrolyte (SE) formed via in situ polymerization, the SE@KANF protective layer for LATP can be constructed. Such a protective layer not only effectively prevents Li metal from reducing LATP but also provides intimate interface contact and limits unnecessary electron transport. Consequently, Li symmetric battery incorporating SE@KANF layer enables an ultrahigh critical current density of 1.4 mA cm−2 and stably cycles for over 2000 h at 0.2 mA cm−2. Moreover, the full SSB coupling with LiFePO4 cathode delivers a capacity retention of 95% after 180 cycles at 0.1 C at 30 °C. The present study underscores the importance of the protective interface layer in stabilizing the LATP|Li interface.