Stabilization the interface of NASICON-type solid electrolyte and Li metal by Al interlayer

Solid-state lithium-ion batteries with intrinsic safety and stable performance have emerged as alternative to liquid electrolyte-based systems. NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) with high ionic conductivity is a promising solid electrolyte to be commercialized. However, the incompatibility of LATP with Li metal hinders its application in high energy density solid-state systems. Herein, we apply a 60 nm thick protective Al layer by PVD to construct a stable interface with metallic Li. The Al-coated LATP enables better electrochemical performance in a symmetric cell than bare LATP. Al-coated LATP is stable at 0.1 mA cm−2 for 100 cycles without building up polarization. The overpotential and the interfacial resistance are significantly reduced as direct contact between Li and LATP is avoided. The Al coating inhibits the reduction of Ti4+ to Ti3+ of LATP pellet during cycling. This work resolves the prominent limitations of LATP and strengthens the interfacial connectivity in solid-state system, pointing an environmental friendly and low cost modification strategy to improve the solid-state lithium-ion batteries.