(Invited) Interfacial Resistance at Atomically-Engineered Interfaces in Solid-State Batteries

Solid-state Li batteries are promising energy-storage devices owing to their high-energy densities with improved safety. However, the large interfacial resistance at the interface of solid-electrolytes and electrodes hinders the development of the solid-state Li batteries. Our group has been investigating surfaces and interfaces of transition-metal oxides, such as SrTiO3, LaAlO3/SrTiO3, SrVO3, La0.7Ca0.3MnO3, and LiTi2O4, using epitaxial thin-film deposition technology and scanning tunneling microscopy [1-7]. Accordingly, we introduced the above knowledge of the atomic-scale investigation of oxide surfaces into battery research. We succeeded in fabricating the interface resistance below 5 Ωcm2(Li3PO4/LiCoO2interface [8,9],Li3PO4/LiNi0.5Mn1.5O4interface [10]); the value is smaller than that of liquid-electrolyte-based Li-ion batteries. These studies strongly encourage solid-state Li battery research, by demonstrating a very low interface resistance leading to fast charging and discharging. References [1] R. Shimizu, K. Iwaya, T. Ohsawa, S. Shiraki, T. Hasegawa, T. Hashizume, and T. Hitosugi, ACS Nano 5, 7967 (2011). [2] K. Iwaya, T. Ogawa, T. Minato, K. Miyoshi, J. Takeuchi, A. Kuwabara, H. Moriwake, Y. Kim, and T. Hitosugi, Phys. Rev. Lett. 111, 126104 (2013). [3] T. Ohsawa, R. Shimizu, K. Iwaya, and T. Hitosugi, ACS Nano 8, 2223 (2014). [4] I. Hamada, R. Shimizu, T. Ohsawa, K. Iwaya, T. Hashizume, M. Tsukada, K. Akagi, and T. Hitosugi, J. Am. Chem. Soc. 136, 17201 (2014). [5] T. Ohsawa, M. Saito, I. Hamada, R. Shimizu, K. Iwaya, S. Shiraki, Z. Wang, Y. Ikuhara, and T. Hitosugi, ACS Nano 9, 8766 (2015). [6] Y. Okada, S.-Y. Shiau, T.-R. Chang, G. Chang, M. Kobayashi, R. Shimizu, H.-T. Jeng, S. Shiraki, H. Kumigashira, A. Bansil, H. Lin, and T. Hitosugi, Phys. Rev. Lett. 119, 086801 (2017). [7] Y. Okada, Y. Ando, R. Shimizu, E. Minamitani, S. Shiraki, S. Watanabe, and T. Hitosugi, Nature Commun. 8, 15975 (2017). [8] M. Haruta, S. Shiraki, T. Suzuki, A. Kumatani, T. Ohsawa, Y. Takagi, R. Shimizu, and T. Hitosugi, Nano Lett. 15, 1498–1502 (2015). [9] S. Shiraki, T. Shirasawa, T. Suzuki, H. Kawasoko, R. Shimizu, and T. Hitosugi, ACS Appl. Mater. Interfaces 10, 41732–41737 (2018). [10]H. Kawasoko, S. Shiraki, T. Suzuki, R. Shimizu, and T. Hitosugi, ACS Appl. Mater. Interfaces 10, 27498 (2018).