High-performance garnet-type solid-state lithium metal batteries enabled by scalable elastic and Li${}^{+}$-conducting interlayer

Promoting the interfacial Li${}^{+}$ transport and suppressing detrimental lithium dendrites are the main challenges for developing practical solid-state lithium metal batteries. In this respect, interface rationalizing to synergize the enhancement of ion transport and suppression of lithium dendrites is of paramount significance. Herein, a novel strategy is demonstrated to address those issues by a designed multifunctional composite interlayer. The photocrosslinkable polymer is introduced in a scalable elastic skeleton, which promotes the migration and diffusion of Li${}^{+}$. Moreover, adding perfluoropolyether in the interlayer benefits to regulating the formation of LiF-rich interface, sufficiently suppress the growth of lithium dendrites. Benefitting from the elasticity, high Li${}^{+}$ conductivity and the lithium dendrites suppression capability, the interlayer can significantly improve the interfacial performance of the solid electrolyte/lithium interface, thus leading to the greatly enhanced electrochemical performance of solid-state lithium metal batteries. A high critical current density of 3.6 mA cm${}^{-2}$ and a long cycling life at 1.0 mA cm${}^{-2}$ for >400 h are achieved for the symmetric cells. Besides, when used in a pouch-type full cell coupled with LiNi${}_{0.6}$Co${}_{0.2}$Mn${}_{0.2}$O${}_2$ cathode, a high charged capacity of 3.25 mAh cm${}^{-2}$ can be maintained through 20 cycles, demonstrating its great potentials for practical application. (© 2023 Wiley-VCH GmbH)