A Vision for LLZO Carbonate Formation: Perspectives on Surface Treatment Approaches and Characterization Techniques
Pedram Ghorbanzade, Pedro López‐Aranguren, Juan Miguel López del Amo
Abstract
Abstract Li 7 La 3 Zr 2 O 12 garnets are among the most promising materials for solid‐state electrolytes thanks to their high electrochemical stability and ionic conductivity. However, they are unstable in air and easily undergo a Li + /H + exchange reaction, forming a lithiophobic and poorly Li‐conducting surface layer composed of LiOH and Li 2 CO 3 upon further reaction with CO 2 . Despite a simple reaction mechanism, protonation of LLZO is a complex phenomenon. The thickness and composition of the secondary phases on the surface depend on many parameters both in the LLZO properties and in the storage atmosphere. Due to this complexity, proposing a universal procedure for removing the secondary phases is not simple. However, understanding the role of different parameters and rational selection of characterization techniques makes it possible to find the optimal conditions for removing the LiOH/Li 2 CO 3 layer and further processing each material. This work compares some of the main approaches for cleaning the LLZO surface and describes their advantages and shortcomings. Additionally, the strengths and limitations of the most common characterization techniques for analyzing the (de)protonation of LLZO (XRD, XPS, Raman, NMR, TGA) are explained to help researchers design their experiments more accurately.