Protective shielding films for atomic-level evaluation of lithium lanthanum zirconium oxide at room temperature

Cubic lithium lanthanum zirconium oxide (c-LLZO) compositions are promising electrolytes for solid-state lithium metal batteries. However, the extremely low tolerance to electron beam irradiation of c-LLZO has hindered direct evaluation and analysis at the atomic scale, for example by scanning transmission electron microscopy (STEM). Herein, we propose a variant of the "nano-shield" method to protect the structures from serious damage due to the energetic electron beam. Using this method, we obtain atomic-resolution STEM images and chemical compositions of c-LLZO along different zone axes at room temperature. Briefly, the nano-shield consists of two amorphous layers, aluminum oxide (AlOx) and carbon, where the insulating AlOx acts as a barrier layer to reduce lithium diffusion rate and the conducting carbon eliminates the charging effect by compensating for the positive charge induced by the incident electrons. The results of the present study facilitate the characterization of the local structures of various beam-sensitive materials.