title: Unusual Li-Ion Transfer Mechanism in Liquid Electrolytes: A First-Principles Study.
abstract: Liquid electrolytes play an important role in commercial lithium-ion (Li-ion) batteries as a conduit for Li-ion transfer between anodes and cathodes. It is generally believed that the Li-ions move along with the salt ions; thus, Li-ion diffusion is only affected by the viscosity and salt concentration in the liquid electrolytes based on the Stokes-Einstein equation. In this study, a novel and faster Li-ion diffusion mechanism in electrolytes containing a cyanogen group is identified from first-principles molecular dynamics (FPMD) simulations. In this mechanism, the Li-ions are first detached from the Li-salt and then diffuse along with the solvent molecules, and the Li-ion diffusion does not obey the traditional Stokes-Einstein equation. The ionic conductivity of the electrolyte systems with this "solvent-assisted Li-ion diffusion" mechanism is further enhanced through Li-ion hopping. This novel Li-ion diffusion process explains recent findings of high Li-ion conductivity in electrolytes with cyanogen groups and furnishes a new paradigm for the design of fast-charging liquid electrolyte for Li-ion batteries.
authors.affiliation: Beijing Computational Science Research Center , Beijing 100084, China.|College of Physics and Electronics Engineering, Hengyang Normal University , Hengyang 421008, China.
authors.forename: Zhen-Kun
authors.initials: ZK
authors.lastname: Tang
authors.affiliation: Beijing Computational Science Research Center , Beijing 100084, China.|Department of Physics and Engineering Physics, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5E2.
authors.forename: John S
authors.initials: JS
authors.lastname: Tse
authors.affiliation: Beijing Computational Science Research Center , Beijing 100084, China.
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Liu