A Perovskite Electrolyte That Is Stable in Moist Air for Lithium‐Ion Batteries

• Published in: Angewandte Chemie (International ed.) Vol. 57; no. 28; pp. 8587 - 8591
• Main Authors: Li, Yutao, Xu, Henghui, Chien, Po‐Hsiu, Wu, Nan, Xin, Sen, Xue, Leigang, Park, Kyusung, Hu, Yan‐Yan, Goodenough, John B.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 09.07.2018; Wiley Blackwell (John Wiley & Sons)
• Edition: International ed. in English
• Subjects: all-solid-state batteries; Batteries; Cathodes; Composite materials; Conducting polymers; Dendritic structure; Electrolytes; Grain boundaries; hybrid Li-S batteries; Interfaces; interfacial resistance; Lithium; Lithium-ion batteries; Molten salt electrolytes; Perovskites; Polymers; Rechargeable batteries; Solid electrolytes; interfacial resistance; perovskites; all-solid-state batteries; hybrid Li-S batteries; electrolytes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201804114

Solid‐oxide Li+ electrolytes of a rechargeable cell are generally sensitive to moisture in the air as H+ exchanges for the mobile Li+ of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell with a solid–electrolyte separator. We report a new perovskite Li+ solid electrolyte, Li0.38Sr0.44Ta0.7Hf0.3O2.95F0.05, with a lithium‐ion conductivity of σLi=4.8×10−4 S cm−1 at 25 °C that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li+‐conducting polymer on its surface to prevent reduction of Ta5+ is wet by metallic lithium and provides low‐impedance dendrite‐free plating/stripping of a lithium anode. It is also stable upon contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all‐solid‐state Li/LiFePO4 cell, a Li‐S cell with a polymer‐gel cathode, and a supercapacitor. A perovskite that is stable in water with 3≤pH≤14 shows small interfacial resistance and excellent cycling performance in an all‐solid‐state Li/LiFePO4 cell, a Li‐S cell, and a supercapacitor.