Mixed Ionic and Electronic Conductor for Li-Metal Anode Protection.

Li-metal is the optimal choice as an anode due to its highest energy density. However, Li-anodes suffer safety problems from dendritic Li-growth and continuous corrosion by liquid electrolytes. Here, an effective strategy of using ultrathin and conformal mixed ionic and electronic ceramic conductor (MIEC) is proposed to stabilize Li-anodes. An ultrathin Li0.35 La0.52 [V]0.13 TiO3 (LLTO) ceramic film with superior ionic conductivity is first obtained by sintering single-crystal LLTO nanoparticles, which have controlled surface facets and particle sizes. Then the MIEC property is developed in the LLTO film by introducing toluene as catalyst, which triggers the chemical reactions between LLTO and Li-metal, leading to high electronic conductivity in the LLTO film. After evaporating toluene, a hybrid LLTO/Li anode with a conformal and stable interface is formed. When applying the hybrid anodes in Li-metal batteries, the MIEC ceramic film blocks Li-corrosion from electrolyte and the formation of Li-dendrites by buffering the Li-ion concentration gradient and leveling secondary current distribution on Li-metal surface. At the same time, the Coulombic efficiency of batteries reaches to 98%. This finding will impact the general approach for tailoring the properties of Li-metal anodes for achieving better Li-metal battery performance.