Mechanical Milling – Induced Microstructure Changes in Argyrodite LPSCl Solid-State Electrolyte Critically Affect Electrochemical Stability

Yixian Wang, Hongchang Hao, Kaustubh G. Naik, Bairav S. Vishnugopi, Cole D. Fincher, Qianqian Yan, Vikalp Raj, Hugo Celio, Guang Yang, Hong Fang, Yet Ming Chiang, Frédéric A. Perras, Puru Jena, John Watt, Partha P. Mukherjee, David Mitlin

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Microstructure of argyrodite solid-state electrolyte (SSE) critically affects lithium metal electrodeposition/dissolution. While the stability of unmodified SSE is mediocre, once optimized state-of-the-art electrochemical performance is achieved (symmetric cells, full cells with NMC811) without secondary interlayers or functionalized current collectors. Planetary mechanical milling in wet media (m-xylene) is employed to alter commercial Li6PS5Cl (LPSCl) powder. Quantitative stereology demonstrates how milling progressively refines grain and pore size/distribution in the SSE compact, increases its density, and geometrically smoothens the SSE-Li interface. Mechanical indentation demonstrates that these changes lead to reduced site-to-site variation in the compact's hardness. Milled microstructures promote uniform early-stage electrodeposition on foil collectors and stabilize solid electrolyte interphase (SEI) reactivity. Analysis of half-cells with bilayer electrolytes demonstrates the importance of microstructure directly contacting current collector, with interface roughness due to pore and grain size distribution being key. For the first time, short-circuiting Li metal dendrite is directly identified, employing 1.5 mm diameter “mini” symmetrical cell and cryogenic focused ion beam (cryo-FIB) electron microscopy. The branching sheet-like dendrite traverses intergranularly, filling the interparticle voids and forming an SEI around it. Mesoscale modeling reveals the relationship between Li-SSE interface morphology and the onset of electrochemical instability, based on underlying reaction current distribution.

Original languageEnglish
Article number2304530
JournalAdvanced Energy Materials
Volume14
Issue number23
DOIs
StatePublished - Jun 19 2024

Keywords

  • argyrodite
  • chemo-mechanical
  • dendrite
  • inorganic solid electrolytes
  • solid-state battery

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