Synergistic rigid-flexible hybrid interface based on PAA and FeF3 towards dendrite-free lithium-oxygen batteries

Lithium metal is regarded as the most promising anode material for high energy density secondary batteries because of its high theoretical specific capacity and low redox potential. Nevertheless, its practical application is severely hindered by poor interfacial stability and uncontrollable dendrite growth. An inorganic/organic composite SEI by coating applied to the surface of Li metal (named FeF 3 -PAA@Li) is created through a chemical in-situ treatment method for the Li metal with a solution including PAA and FeF 3 , which is made of a flexible LiPAA organic matrix in which rigid LiF, FeF 2 , and Li Fe alloy inorganic nanoparticles are embedded. The soft LiPAA matrix acts as a chemically inert and stretchable skin, effectively accommodating volume changes and avoiding additional parasitic reactions. Meanwhile, the inorganic nanoparticles provide enhanced structural robustness to impede proliferation of Li dendrites and enable uniform Li + distribution for even Li electroplating. Thus, both Li O 2 cells and Li||Li symmetric cells incorporating FeF 3 -PAA@Li show a low overpotential and consistent cycling stability. This SEI design offers a viable pathway for enabling stable and high-efficiency Li O 2 batteries in practical settings.