Insights into the Lithium Nucleation and Plating/Stripping Behavior in Ionic Liquid-Based Electrolytes

ACS Applied Materials & Interfaces, vol. 15, pp. 25462–25472

Abstract

Rechargeable lithium–metal batteries (LMBs) are anticipated to enable enhanced energy densities, which can be maximized when minimizing the amount of excess lithium in the cell down to zero, also referred to as “zero excess” LMBs. In this case, the only source of lithium is the positive electrode active material─just like in lithium-ion batteries. However, this requires the fully reversible deposition of metallic lithium, i.e., the Coulombic efficiency (CE) approaching 100%. Herein, the lithium plating from ionic liquid-based electrolytes, composed of N -butyl- N -methyl pyrrolidinium bis(fluorosulfonyl)imide (PYR 14 FSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the conducting salt, on nickel current collectors is investigated via a comprehensive set of electrochemical techniques coupled with operando and in situ atomic force microscopy and ex situ X-ray photoelectron spectroscopy. The investigation involves the use of fluoroethylene carbonate (FEC) as an electrolyte additive. The results show that an elevated LiTFSI concentration leads to a lower overpotential for the lithium nucleation and a more homogeneous deposition. The incorporation of FEC results in a further lowered overpotential and a stabilized solid electrolyte interphase, enabling a substantially enhanced CE.

Authors 7

1. Dominik Stępień

   Karlsruhe Institute of Technology · Helmholtz-Institute Ulm

   Affiliation as printed

   Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany

   Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany

2. Beatrice Wolff Aachen Institute of Physical Chemistry

   RWTH Aachen University · Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy and Climate Research IEK-9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany

3. Thomas Diemant

   Karlsruhe Institute of Technology · Helmholtz-Institute Ulm

   Affiliation as printed

   Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany

   Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany

4. Guk‐Tae Kim

   Karlsruhe Institute of Technology · Helmholtz-Institute Ulm

   Affiliation as printed

   Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany

   Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany

5. Florian Hausen corresponding Aachen Institute of Physical Chemistry

   RWTH Aachen University · Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy and Climate Research IEK-9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany

6. Dominic Bresser corresponding

   Karlsruhe Institute of Technology · Helmholtz-Institute Ulm

   Affiliation as printed

   Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany

   Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany

7. Stefano Passerini corresponding

   Sapienza University of Rome · Karlsruhe Institute of Technology · Helmholtz-Institute Ulm

   Affiliation as printed

   Chemistry Department, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy

   Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany

   Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany