title: Homogeneous lithium electrodeposition with pyrrolidinium-based ionic liquid electrolytes.
abstract: In this study, we report on the electroplating and stripping of lithium in two ionic liquid (IL) based electrolytes, namely N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyr14FSI) and N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI), and mixtures thereof, both on nickel and lithium electrodes. An improved method to evaluate the Li cycling efficiency confirmed that homogeneous electroplating (and stripping) of Li is possible with TFSI-based ILs. Moreover, the presence of native surface features on lithium, directly observable via scanning electron microscope imaging, was used to demonstrate the enhanced electrolyte interphase (SEI)-forming ability, that is, fast cathodic reactivity of this class of electrolytes and the suppressed dendrite growth. Finally, the induced inhomogeneous deposition enabled us to witness the SEI cracking and revealed previously unreported bundled Li fibers below the pre-existing SEI and nonrod-shaped protuberances resulting from Li extrusion.
authors.affiliation: †Helmholtz-Institut Ulm (HIU) Electrochemistry I, Albert-Einstein-Allee 11, 89081 Ulm, Germany.|‡Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.|§Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Grande
authors.affiliation: †Helmholtz-Institut Ulm (HIU) Electrochemistry I, Albert-Einstein-Allee 11, 89081 Ulm, Germany.|‡Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.|§Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: von Zamory
authors.affiliation: †Helmholtz-Institut Ulm (HIU) Electrochemistry I, Albert-Einstein-Allee 11, 89081 Ulm, Germany.|‡Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.|§Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Stephan L
authors.initials: SL
authors.lastname: Koch
authors.affiliation: §Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Kalhoff
authors.affiliation: †Helmholtz-Institut Ulm (HIU) Electrochemistry I, Albert-Einstein-Allee 11, 89081 Ulm, Germany.|‡Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.|§Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Elie
authors.initials: E
authors.lastname: Paillard
authors.affiliation: †Helmholtz-Institut Ulm (HIU) Electrochemistry I, Albert-Einstein-Allee 11, 89081 Ulm, Germany.|‡Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.|§Institute of Physical Chemistry, University of Münster, Corrensstraße 28-30, 48149 Münster, Germany.
authors.forename: Stefano
authors.initials: S
authors.lastname: Passerini
keywords: SEI; dendrites; energy storage; ionic liquids; lithium metal; nickel