By Prof. Masataka Nagaoka, Nagoya University, Japan.
Recently, we have developed a new efficient hybrid Monte Carlo (MC)/molecular dynamics (MD) reaction method with a rare event-driving mechanism, i.e., Red Moon method  as a practical ‘atomistic’ molecular simulation method of large-scale chemically reaction systems (Fig. 1). So far, Red Moon method  has been successfully applied to several complex materials . In this talk, our recent applications of Red Moon method to secondary batteries are shown from the practical viewpoint of molecular controlling of solid electrolyte interphase (SEI) film formation [3a-f].
In investigating SEI films in lithium-ion batteries (LIB) [4a] and sodium-ion batteries (NIB) [4b], it is well-known that the SEI film formation is strongly sensitive to the small structural difference of electrolyte molecules [4a] and the additive molecules [4a-c]. In particular, fluoroethylene carbonate (FEC) additive is known to in-crease considerably the NIB performance [4b, 4c], while difluoroethylene carbonate (DFEC) is inefficient in spite of its being a similar molecule substituted by only one fluorine atom [3b, 3c]. Such fine behavior of electrolyte additives in the NIBs is not thoroughly understood microscopically, e.g., the FEC-DFEC mystery.
Hence, in this talk, considering important theoretical findings in the DFEC reduction reactions [3c], we will discuss the SEI film formation on the anode surface in the DFEC-added PC electrolyte system and, further, will show the FEC concentration effect on SEI formation in the FEC-added PC electrolyte systems, comparing with our previous theoretical studies [3a-c]. Finally, it will be reconfirmed theoretically that the appropriate adjustment of the amount of FEC additive is essential to develop the high-performance of NIB [3e].
LIB, NIB, Additive effect, Red Moon methodology, Computational molecular technology.
 (a) M. Nagaoka, Y. Suzuki, T. Okamoto and N. Takenaka, Chem. Phys. Letters 583, 80-86 (2013); (b) Y. Suzuki and M. Nagaoka, J. Chem. Phys., 146, 204102 (2017); (c) http://www.mt.jst.go.jp/en/researchers/masataka_nagaoka. html.
 (a) Y. Suzuki, Y. Koyano and M. Nagaoka, J. Phys. Chem. B, 119, 6776-6785 (2015).
 (a) N. Takenaka, Y. Suzuki, H. Sakai and M. Nagaoka. J. Phys. Chem. C, 118, 10874-10882 (2014); (b) N. Takenaka, H. Sakai, Y. Suzuki, P. Uppula and M. Nagaoka. Ibid., 119, 18046-18055 (2015); (c) P. Uppula, N. Takenaka and M. Nagaoka. RSC Advances, 6, 65232-65242 (2016); (d) N. Takenaka, T. Fujie, A. Bouibes, Y. Yamada, A. Yamada, M. Nagaoka, J. Phys. Chem. C, 122, 2564-2571 (2018); (e) A. Bouibes, N. Takenaka, T. Fu-jie, K. Kubota, S. Komaba, M. Nagaoka, ACS Applied Materials & Interfaces, 10, 28525-28532 (2018); (f) T. Fujie, N.Takenaka, Y.Suzuki, M. Nagaoka, The Journal of Chemical Physics, 149, 044113 (2018).
 (a) K. Xu, Chem. Rev., 114, 11503−11618 (2014); (b) N. Yabuuchi, K. Kubota, M. Dahbi and S. Komaba, Chem. Rev., 114, 11636-11682 (2014); (c) M. Dahbi, T. Nakano, N. Yabuuchi, S. Fujimura, K. Chihara, K. Kubota, J.-Y. Son, Y.-T. Cui, H. Oji and S. Komaba, ChemElectroChem, 3, 1856-1867 (2016).
(Will be updated soon)
Prof. Masataka Nagaoka
1) Graduate School of Informatics, Nagoya University, Nagoya, Japan,
2) Core Research for Evolutional Science and Technology (CREST), JST, Kawaguchi, Japan,
3) Element Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, Kyoto, Japan