Stable Separator Identified for High-Energy Batteries

State-of-the-art scanning transmission electron microscopy (STEM) unveiled the structural stability of lithium lanthanum zirconium oxide (LLZO) garnet in aqueous media. The solid electrolyte material has excellent stability across a wide pH range, making it promising for long-operating novel batteries with both a Li metal anode and an aqueous catholyte (portion of the electrolyte close to the cathode). Solid electrolytes for aqueous media are crucial for lithium-air batteries that have an energy density about 10 times higher than conventional Li-ion batteries. The present study benefits the development of multiple novel battery technologies beyond state-of-the-art Li-ion batteries.

Although observed in experiments, the structural stability of LLZO in neutral and strong basic aqueous environments has not been confirmed at the atomic level. In this study, microscopic interactions between LLZO and aqueous solutions were elucidated through atomic-level imaging. Reversible Li /H exchange was  confirmed at particular crystallographic positions without affecting the cubic structure of LLZO. Thus the cubic LLZO is free from the severe protonation-induced conductivity degradation that occurs in other garnets. 

 

Cheng Ma, Ezhiylmurugan Rangasamy, Chengdu Liang, Jeffrey Sakamoto, Karren L. More, and Miaofang Chi,  “Excellent Stability of a Li-Ion-Conducting Solid Electrolyte upon Reversible Li /H Exchange in Aqueous Solutions,” Angewandte Chemie International Edition (2014).  DOI: 10.1002/anie.201408124

 

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