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

Tuesday, 11 October 2022: 09:20
Room 223 (The Hilton Atlanta)
D. Stepien (Karlsruher Institute of Technology (KIT), Helmholtz Insitute Ulm (HIU)), B. Wolff (IEK-9 Forschungszentrum Jülich, RWTH Aachen University), T. Diemant (Karlsruher Institute of Technology (KIT), Helmholtz Institute Ulm (HIU)), G. T. Kim (Karlsruhe Institute of Technology (KIT), Helmholtz Institute Ulm (HIU)), F. Hausen (IEK-9 Forschungszentrum Jülich, RWTH Aachen University), D. Bresser (Karlsruhe Institute of Technology, Helmholtz Institute Ulm), and S. Passerini (Helmholtz Institute Ulm (HIU), Karlsruhe Institute of Technology (KIT))
Lithium-metal batteries are anticipated to become the next-generation battery technology, allowing for substantially higher energy densities. To maximize the energy density, however, a “zero excess” of lithium in the cell is a must, e.g., by initially storing all electrochemically active lithium in the positive electrode.1 Nevertheless, this requires the fully reversible deposition of metallic lithium, i.e., a Coulombic efficiency of essentially 100%.2

Herein, the investigation of the lithium nucleation and plating/stripping from ionic liquid-based electrolytes composed of N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) on nickel current collectors is reported, involving a comprehensive set of electrochemical techniques coupled with operando and in situ atomic force microscopy and ex situ X-ray photoelectron spectroscopy. It was found that the morphology of the deposited lithium, the chemical composition of the interphase formed on the nickel current collector, and the reversibility of the lithium plating and stripping is highly dependent on the ratio of the ionic liquid and the lithium salt. Moreover, the addition of suitable film-forming additives allows for lower overpotentials and greater reversibility by tuning the interphase composition. The results are anticipated to contribute to the development of advanced electrolyte systems for “zero excess” lithium-metal batteries.

(1) Nanda, S., Gupta, A., and Manthiram, A. Anode-Free Full Cells: A Pathway to High-Energy Density Lithium-Metal Batteries. Adv. Energy Mater. 2021, 11, 2000804. DOI: 10.1002/aenm.202000804

(2) Hobold, G.M., Lopez, J., Guo, R. et al. Moving beyond 99.9% Coulombic efficiency for lithium anodes in liquid electrolytes. Nat. Energy 2021, 6, 951–960. DOI: 10.1038/s41560-021-00910-w

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