Regulating Li‐ion Flux through a Dense yet Highly Ionic Conductive Interlayer for Stable Li Deposition

Abstract The practical use of Li metal anode is severely hindered by the uncontrollable dendrite growth, and the main cause is the uneven deposition of Li metal. In the liquid electrolyte, the Li‐ion distribution on the electrode surface is difficult to be regulated, which largely affects the Li deposition behavior. The authors design a dense Li‐ion flux regulating layer on the separator to well guide the Li‐ion transport that is composed of metal/lithium oxide (Li₂O). Such a layer is generated from the in situ lithiation of transition metal oxide nanoparticle (TMO NP) coating, in which the lithiation‐induced volume expansion of TMO NPs makes the coating very dense yet highly ionic conductive due to the rich boundaries between the formed metal/Li₂O. Such a layer enables the redistribution of Li ions on the surface of the electrode to effectively suppress the dendrite growth. The symmetric cells with such layers maintain stable cycling over 400 h under 3 mA cm^–2, and the full cell coupled with LiFePO₄ presents a highly stable cycling performance with high‐capacity retention of 85.2% after 350 cycles at 0.5 C with a low N/P ratio, promising a potential application in next‐generation Li metal batteries.