Stabilizing the Li<sub>1.3</sub>Al<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub>|Li Interface for High Efficiency and Long Lifespan Quasi‐Solid‐State Lithium Metal Batteries
Zhen Chen, Dominik Stępień, Fanglin Wu, Maider Zarrabeitia, Hai‐Peng Liang, Jae‐Kwang Kim, Guk‐Tae Kim, Stefano Passerini
Abstract
Abstract To tackle the poor chemical/electrochemical stability of Li 1+ x Al x Ti 2‐ x (PO 4 ) 3 (LATP) against Li and poor electrode|electrolyte interfacial contact, a thin poly[2,3‐bis(2,2,6,6‐tetramethylpiperidine‐ N ‐oxycarbonyl)norbornene] (PTNB) protection layer is applied with a small amount of ionic liquid electrolyte (ILE). This enables study of the impact of ILEs with modulated composition, such as 0.3 lithium bis(fluoromethanesulfonyl)imide (LiFSI)‐0.7 N ‐butyl‐ N ‐methylpyrrolidinium bis(fluoromethanesulfonyl)imide (Pyr 14 FSI) and 0.3 LiFSI‐0.35 Pyr 14 FSI‐0.35 N ‐butyl‐ N ‐methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr 14 TFSI), on the interfacial stability of PTNB@Li||PTNB@Li and PTNB@Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells. The addition of Pyr 14 TFSI leads to better thermal and electrochemical stability. Furthermore, Pyr 14 TFSI facilitates the formation of a more stable Li|hybrid electrolyte interface, as verified by the absence of lithium “pitting corrosion islands” and fibrous dendrites, leading to a substantially extended lithium stripping‐plating cycling lifetime (>900 h). Even after 500 cycles (0.5C), PTNB@Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells achieve an impressive capacity retention of 89.1 % and an average Coulombic efficiency of 98.6 %. These findings reveal a feasible strategy to enhance the interfacial stability between Li and LATP by selectively mixing different ionic liquids.