Open AccessOn the Relative Importance of Li Bulk Diffusivity and Interface Morphology in Determining the Stripped Capacity of Metallic Anodes in Solid-State Batteries
Author(s) -
Marco Siniscalchi,
Junliang Liu,
Joshua S. Gibson,
Stephen J. Turrell,
Jack Aspinall,
Robert S. Weatherup,
Mauro Pasta,
Susannah Speller,
C.R.M. Grovenor
Publication year - 2022
Publication title -
acs energy letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.632
H-Index - 105
ISSN - 2380-8195
DOI - 10.1021/acsenergylett.2c01793
Subject(s) - lithium (medication) , thermal diffusivity , diffusion , electrolyte , materials science , anode , electrode , alloy , limiting current , atomic diffusion , chemical engineering , electrochemistry , chemistry , metallurgy , thermodynamics , crystallography , medicine , endocrinology , physics , engineering
Lithium metal self-diffusion is too slow to sustain large current densities at the interface with a solid electrolyte, and the resulting formation of voids on stripping is a major limiting factor for the power density of solid-state cells. The enhanced morphological stability of some lithium alloy electrodes has prompted questions on the role of lithium diffusivity in these materials. Here, the lithium diffusivity in Li-Mg alloys is investigated by an isotope tracer method, revealing that the presence of magnesium slows down the diffusion of lithium. For large stripping currents the delithiation process is diffusion-limited, hence a lithium metal electrode yields a larger capacity than a Li-Mg electrode. However, at lower currents we explain the apparent contradiction that more lithium can be extracted from Li-Mg electrodes by showing that the alloy can maintain a more geometrically stable diffusion path to the solid electrolyte surface so that the effective lithium diffusivity is improved.