Magnetic Actuation Enables Programmable Lithium Metal Engineering

Abstract Lithium metal anodes may allow the energy density limit of rechargeable lithium batteries to be pushed higher. However, simple and efficient processing technologies for thin Li metal are lacking, which has significantly limited its applications. Herein, the feasibility of engineering Li metal by compositing it with ferromagnetic particles (termed magnetic Li, abbr. M‐Li) is reported. Due to its magnetic response, straightforward processing of M‐Li on diverse substrates with customized patterns and desired thickness is realized. Moreover, when a garnet‐type solid‐state electrolyte Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO) is the substrate, intimate contact between M‐Li and LLZTO is obtained, with a low interfacial resistance of ≈11 Ω cm 2 . In addition to facilitating movement and wetting on various substrates, magnetic transfer of M‐Li sheets to designated locations is also enabled. The intriguing and brand‐new method for Li metal engineering via magnetic actuation may be adopted by the industrial system for the fabrication of Li metal batteries, extended to other alkali metals and promises further progress.