Li⁺ concentration and morphological changes at the anode and cathode interphases inside solid-state lithium metal batteries
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Author(s)
Type
Journal Article
Abstract
Irregular Li heterostructure growth at the interphase between the solid electrolyte and anode
reduces solid-state Li metal battery (SSLMB) performance, but the fundamental cause is still
elusive. Measuring and imaging Li+ ion diffusion in operando inside an SSLMB using a
commercially standard cell configuration are extremely challenging because the ultra-light Li
element exhibits a minute signal-to-noise ratio using most x-ray-related characterization methods,
and the weak x-ray signals of Li+ are buried by strong signals of other heavy transition metal
elements in the cathode and battery enclosure. Here, we pioneer novel operando correlative
imaging of coupling x-ray Compton scattering with computed tomography (XCS-CT), which is
able to quantify the interplay between spatially resolved Li+ ion diffusion kinetics and Li0 metal
structure growth at the interphases of both the anode and cathode sides inside a full-cell SSLMB
using a solid polymer electrolyte (SPE) and commercially standard cell configuration during
(dis)charging. We show a 61% increase in the efficiency of extracting Li+ ions from the cathode
LiNi0.6Mn0.2Co0.2O2 to the anode during charging at 0.1 C compared with at 1 C due to restricted
Li+ ion diffusion at the higher rate inside SSLMB. However, this led to the formation of a more
irregular interfacial morphology, consisting not only of Li0 dendrites, but also sub-surface pore
formation at the anode/SPE interphase. We find that surprisingly, the irregular Li0
structure
initiation and growth are accelerated during the first Li stripping step, not the Li plating step, and
the root cause is the onset imbalance of Li+ ion diffusion and redox reactions between the anode
and cathode. These insights highlight the benefits of asymmetric charging and discharging rates as
a promising solution to improving SSLMB performance with SPEs. The operando correlative
XCS-CT imaging technique has the potential to study the relationship between active ion
concentrations and buried morphological changes for a variety of battery chemistries.
reduces solid-state Li metal battery (SSLMB) performance, but the fundamental cause is still
elusive. Measuring and imaging Li+ ion diffusion in operando inside an SSLMB using a
commercially standard cell configuration are extremely challenging because the ultra-light Li
element exhibits a minute signal-to-noise ratio using most x-ray-related characterization methods,
and the weak x-ray signals of Li+ are buried by strong signals of other heavy transition metal
elements in the cathode and battery enclosure. Here, we pioneer novel operando correlative
imaging of coupling x-ray Compton scattering with computed tomography (XCS-CT), which is
able to quantify the interplay between spatially resolved Li+ ion diffusion kinetics and Li0 metal
structure growth at the interphases of both the anode and cathode sides inside a full-cell SSLMB
using a solid polymer electrolyte (SPE) and commercially standard cell configuration during
(dis)charging. We show a 61% increase in the efficiency of extracting Li+ ions from the cathode
LiNi0.6Mn0.2Co0.2O2 to the anode during charging at 0.1 C compared with at 1 C due to restricted
Li+ ion diffusion at the higher rate inside SSLMB. However, this led to the formation of a more
irregular interfacial morphology, consisting not only of Li0 dendrites, but also sub-surface pore
formation at the anode/SPE interphase. We find that surprisingly, the irregular Li0
structure
initiation and growth are accelerated during the first Li stripping step, not the Li plating step, and
the root cause is the onset imbalance of Li+ ion diffusion and redox reactions between the anode
and cathode. These insights highlight the benefits of asymmetric charging and discharging rates as
a promising solution to improving SSLMB performance with SPEs. The operando correlative
XCS-CT imaging technique has the potential to study the relationship between active ion
concentrations and buried morphological changes for a variety of battery chemistries.
Date Issued
2025-04-01
Date Acceptance
2025-01-29
Citation
Journal of Physics: Energy, 2025, 7 (2)
ISSN
2515-7655
Publisher
IOP Publishing
Journal / Book Title
Journal of Physics: Energy
Volume
7
Issue
2
Copyright Statement
© 2025 The Author(s). Published by IOP Publishing Ltd Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
License URL
Identifier
10.1088/2515-7655/adafda
Subjects
solid-state batteries
correlative imaging
lithium ion concentration
microstructure
x-ray Compton scattering
mass transport
Publication Status
Published
Article Number
025009
Date Publish Online
2025-02-12