title: Superconcentrated electrolytes for a high-voltage lithium-ion battery.
abstract: Finding a viable electrolyte for next-generation 5 V-class lithium-ion batteries is of primary importance. A long-standing obstacle has been metal-ion dissolution at high voltages. The LiPF6 salt in conventional electrolytes is chemically unstable, which accelerates transition metal dissolution of the electrode material, yet beneficially suppresses oxidative dissolution of the aluminium current collector; replacing LiPF6 with more stable lithium salts may diminish transition metal dissolution but unfortunately encounters severe aluminium oxidation. Here we report an electrolyte design that can solve this dilemma. By mixing a stable lithium salt LiN(SO2F)2 with dimethyl carbonate solvent at extremely high concentrations, we obtain an unusual liquid showing a three-dimensional network of anions and solvent molecules that coordinate strongly to Li(+) ions. This simple formulation of superconcentrated LiN(SO2F)2/dimethyl carbonate electrolyte inhibits the dissolution of both aluminium and transition metal at around 5 V, and realizes a high-voltage LiNi0.5Mn1.5O4/graphite battery that exhibits excellent cycling durability, high rate capability and enhanced safety.
authors.affiliation: Department of Chemical System Engineering, University of Tokyo, 7-3-1, Hongo, Tokyo 113-8656, Japan.
authors.forename: Jianhui
authors.identifier: 0000-0002-4170-1132
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemical System Engineering, University of Tokyo, 7-3-1, Hongo, Tokyo 113-8656, Japan.|Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30, Goryo-Ohara, Kyoto 615-8245, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30, Goryo-Ohara, Kyoto 615-8245, Japan.|JST PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan.|International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1, Namiki, Tsukuba 305-0044, Japan.
authors.forename: Keitaro
authors.initials: K
authors.lastname: Sodeyama
authors.affiliation: Department of Chemical System Engineering, University of Tokyo, 7-3-1, Hongo, Tokyo 113-8656, Japan.
authors.forename: Ching Hua
authors.initials: CH
authors.lastname: Chiang
authors.affiliation: Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30, Goryo-Ohara, Kyoto 615-8245, Japan.|International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1, Namiki, Tsukuba 305-0044, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tateyama
authors.affiliation: Department of Chemical System Engineering, University of Tokyo, 7-3-1, Hongo, Tokyo 113-8656, Japan.|Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30, Goryo-Ohara, Kyoto 615-8245, Japan.
authors.forename: Atsuo
authors.initials: A
authors.lastname: Yamada