Cyclic electrochemical reactions on a Li-metal negative electrode having a low-resistance interface with a solid-state electrolyte

• Published in: Applied physics letters 2024-04, Vol.124 (18)
• Main Authors: Kuwajima, Hideaki, Watanabe, Yuki, Ikezawa, Keita, Yasuda, Toshikazu, Shimizu, Ryota, Masuyama, Tomoki, Nakayama, Yuri, Hitosugi, Taro
• Format: Article
• Language: English
• Subjects: Chemical reactions; Contamination; Electrode materials; Electrodes; Electrolytes; Interface stability; Low resistance; Oxidation; Performance degradation; Plating; Solid electrolytes; Solid state
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0201538

Li metal is a promising negative-electrode material for high-energy-density all-solid-state batteries. However, the surface of Li metal is prone to oxidation, which results in the formation of a contamination layer at the Li metal–solid electrolyte interface. This interfacial contamination layer is the root cause of short-circuiting and poor cycle stability, thus hindering the development of all-solid-state batteries. Prior studies have not quantitatively assessed the effect of the above layer on battery performance. Herein, the degradation mechanisms affecting the interface are investigated using alternating-current impedance measurements and Li plating–stripping cycle tests for a symmetric cell. A thin contamination layer results in a Li–electrolyte interface with a low resistance of 0.20 kΩ cm2 and stable Li plating–stripping behavior at a current density of 3 mA cm−2, whereas a thick contamination layer results in a high interfacial resistance of 2.0 kΩ cm2. The thinning of the contamination layer on Li metal enhances the stability of the Li–electrolyte interface and Li plating–stripping kinetics.