Engineering and regulating the interfacial stability between LiAlTi(PO)-based solid electrolytes and lithium metal anodes for solid-state lithium batteries.

InCl@LiAlTi(PO)-F (InCl@LATP-F) solid electrolyte powders are designed and fabricated by coating a uniform InCl layer on the surface of F-doped LiAlTi(PO) (LATP-F) solid powders via a feasible wet-chemical technique. The assembled Li/InCl@LATP-F/Li cell can undergo longer cycles of 2500 h at 0.4 mA cm without obvious increases in the overvoltage compared to 1837 h for the Li/LATP-F/Li cell, and the interfacial resistance demonstrates a sharp decrease from 3428 to 436 Ω for the Li/InCl@LATP-F/Li cell during the first 500 h. Importantly, the assembled LiCoO/InCl@LATP-F/Li cell delivers a high discharge specific capacity of 126.4 mAh g with a 95.42% capacity retention ratio after 100 cycles at 0.5 C, and the value easily returns to 112.9 mAh g when the current density is abruptly set back to 0.1 C after different rate cycles. These improved results can be mainly attributed to the fact that the InCl layer with a lithiophilic nature can react with lithium metal to form a Li-In alloy, which can guarantee homogeneous lithium ion flux to avoid the accumulation of ions/electrons across the interface and suppress the growth of lithium dendrites. Moreover, the InCl layer can prevent direct contact of the LATP-F solid electrolyte and lithium metal to effectively alleviate the reduction reaction of Ti and preserve the structural stability of the composite electrolyte. Therefore, this work may provide an effective strategy to engineer and regulate the interfacial stability between LATP solid electrolytes and lithium metal anodes for LATP-type solid-state lithium batteries.