Revealing Li dynamics in mixed ionic-electronic conducting interlayer of all-solid-state batteries

27 September 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Lithium-metal (Li0) anode is considered the holy grail of all-solid-state batteries owing to their exceedingly high energy density; in practice, their stability remains unsatisfactory because of the incompatibility between Li0 and solid-state electrolytes (SEs). One strategy is introducing an interlayer, which often consists of the mixed ionic-electronic conductor (MIEC), to stabilize the Li0. However, how Li ions (Li+) transport within MIEC remains unknown. Herein, we investigate the Li, including Li0 and Li+, dynamics in a graphite interlayer, a typical MIEC, using operando neutron imaging and Raman spectroscopy. Our study reveals the Li evolution during mechano-chemistry and mechano-electrochemistry reactions. During cell assembly, intercalation–extrusion-dominated mechano-chemical reactions transform the graphite into a Li-graphite interlayer consisting of SE, Li0, and diluted graphite-intercalation compounds. During battery operation, dictated by the lowest nucleation energy, Li0 plating preferentially occurred at the Li-graphite|SE interface and then transferred into the Li-graphite interlayer without intercalation. Upon further plating, Li0-dendrites formed, inducing short circuits and reverse immigration of Li0 from the anode to the cathode during charging. Continuum modeling was conducted to explain the Li dynamics. We concluded that with the MIEC interlayer, a lowest nucleation barrier at the Li0 side is necessary to drive the Li+ to transport across MIEC and preferentially deposit onto the Li0.

Keywords

Solid-state batteries
Lithium metal
Neutron imgaing
Raman spectroscopy
Operando investigation
Mixed ionic-electronic conductor

Supplementary materials

Title
Description
Actions
Title
Supporting information
Description
The supporting information includes Note S1-S11, Fig. S1-S22, and Supplemental Tables.
Actions
Title
Video S1
Description
Video S1 shows the battery's dynamic normalized neutron radiograph images during charging.
Actions
Title
Video S2
Description
Video S2 illustrates the dynamic of Li with MIEC in the processes including mechanochemical and mechano-electrochemical reactions.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.