Lithium Ion Pathway within Li7La3Zr2O12-Polyethylene Oxide Composite Electrolytes

• Published in: Angewandte Chemie (International ed.) Vol. 55; no. 40; pp. 12538 - 12542
• Main Authors: Zheng, Jin, Tang, Mingxue, Hu, Yan-Yan
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 26.09.2016; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: 6,7Li NMR; 7Li NMR; Batteries; Battery cycles; Ceramics; Composite materials; Conductivity; Conductors; diffusion pathways; Electrodes; Electrolytes; Electrolytic cells; Energy harvesting; Energy storage; High resolution; Ion currents; Ions; isotope labeling; Labels; Lithium; Lithium batteries; lithium ion batteries; Lithium isotopes; Marking; Mechanical properties; Metals; Monitoring; NMR; Nuclear magnetic resonance; Optimization; Polyethylene; Polyethylene oxide; Polyethylenes; Rechargeable batteries; Safety; solid-state electrolytes; Symmetry
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201607539

Polymer–ceramic composite electrolytes are emerging as a promising solution to deliver high ionic conductivity, optimal mechanical properties, and good safety for developing high‐performance all‐solid‐state rechargeable batteries. Composite electrolytes have been prepared with cubic‐phase Li7La3Zr2O12 (LLZO) garnet and polyethylene oxide (PEO) and employed in symmetric lithium battery cells. By combining selective isotope labeling and high‐resolution solid‐state Li NMR, we are able to track Li ion pathways within LLZO‐PEO composite electrolytes by monitoring the replacement of 7Li in the composite electrolyte by 6Li from the 6Li metal electrodes during battery cycling. We have provided the first experimental evidence to show that Li ions favor the pathway through the LLZO ceramic phase instead of the PEO‐LLZO interface or PEO. This approach can be widely applied to study ion pathways in ionic conductors and to provide useful insights for developing composite materials for energy storage and harvesting. Where do they go? The first experimental evidence was obtained for lithium ions diffusing through composite ceramic electrolytes (LLZO and PEO) in an all‐solid‐state battery. Lithium ion diffusion was determined using 6,7Li NMR and isotope exchange, and indicated that Li ions mainly pass through the LLZO ceramic phase instead of the LLZO‐PEO interface or the PEO phase.