Intrinsic Lithiophilicity of Li–Garnet Electrolytes Enabling High‐Rate Lithium Cycling

• Published in: Advanced functional materials 2020-02, Vol.30 (6), p.n/a
• Main Authors: Zheng, Hongpeng, Wu, Shaoping, Tian, Ran, Xu, Zhenming, Zhu, Hong, Duan, Huanan, Liu, Hezhou
• Format: Article
• Language: English
• Subjects: critical current density; Dendritic structure; Electrolytes; Electrolytic cells; Flux density; Impedance; Impurities; interface; Interfacial properties; Ion currents; Lithium; Lithium batteries; Lithium-ion batteries; lithium–garnet; Materials science; Organic chemistry; Product safety; Room temperature; solid electrolyte; Solid electrolytes; solid‐state lithium batteries; Wettability
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201906189

Solid‐state lithium batteries are widely considered as next‐generation lithium‐ion battery technology due to the potential advantages in safety and performance. Among the various solid electrolyte materials, Li–garnet electrolytes are promising due to their high ionic conductivity and good chemical and electrochemical stabilities. However, the high electrode/electrolyte interfacial impedance is one of the major challenges. Moreover, short circuiting caused by lithium dendrite formation is reported when using Li–garnet electrolytes. Here, it is demonstrated that Li–garnet electrolytes wet well with lithium metal by removing the intrinsic impurity layer on the surface of the lithium metal. The Li/garnet interfacial impedance is determined to be 6.95 Ω cm2 at room temperature. Lithium symmetric cells based on the Li–garnet electrolytes are cycled at room temperature for 950 h and current density as high as 13.3 mA cm−2 without showing signs of short circuiting. Experimental and computational results reveal that it is the surface oxide layer on the lithium metal together with the garnet surface that majorly determines the Li/garnet interfacial property. These findings suggest that removing the superficial impurity layer on the lithium metal can enhance the wettability, which may impact the manufacturing process of future high energy density garnet‐based solid‐state lithium batteries. By removing the impurity layer on the surface of the lithium metal, Li–garnet electrolytes are demonstrated to well wet the lithium metal, rendering a Li/garnet interfacial impedance of 6.95 Ω cm2, stable galvanostatic cycling for 950 h, and a current density as high as 13.3 mA cm−2 without showing any sign of short circuiting at room temperature.