Cross-section ✂️ 2017...
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2 min read
🔍 Overview
To investigate in depth morphology and chemical distribution of composite materials and electrodes, I developed cross-sectioning methods using Ar+ ions beam coupled to Auger analysis. It allows analyzing morphological and chemical informations of a micro-scale region of interest with a nano-scale resolution (~30 nm lateral, ~3 nm depth). This approach was applied to:
- Composite electrodes based on conversion materials for batteries: conversion materials such as MSnSb (M=Ti or Nb) overcome huge volume expansion (>200%) and very fast amorphization so that conventional XRD/SAXS as well as TEM (focusing individual particles) are unsuitable tecnhiques to study their reversibility. This was performed in collaboration with L. Monconduit (ICGM).
- Nano-composite powders for supercaps: MnO2-CoOOH performance being governed by their assembly, morphology and porosity at both the nano- and micro-scales, standard XRD (coherent domain size), SEM (surface) and TEM (individual particles) are unsuitable tecnhiques to fully asses their properties at once. It started as a preliminary collaboration with D. Giaume (Chimie ParisTech) and L. Guerlou-Demourgues (ICMCB) through the RS2E network. As the result were conclusive, this method was pursued in a larger project funded by the REGION Nouvelle-Aquitaine and led by D. Flahaut (IPREM).
🎯 Key Findings
- Composite electrodes: The cross-section/Auger approach demonstrated for the first time that conversion of MSnSb (M=Ti or Nb) still occurs after 400 cycles. It occurs through a shell to core expansion/break up of the particles upon cycling. This leads to a micron scale spreading that fills the initially large and highly porous structure of the electrodes together with a large electrode volume expansion.
- Composite powders: The cross-section/Auger approach revealed for the first the Mn-Co scale organization together with the morphology and porosity at both the micro-particles and nano scales.
👤 My Contributions
- Development of both the electrodes / powders cross-sectioning and Auger analysis protocols with the support of J.-B. Ledeuil (CNRS Research Engineer, IPREM).
- Co-supervision of 🎓 A. Lemoine’s PhD thesis (20%).
📢 Communication
📄 6 publications
🎤 2 international conferences
🚀 Next Steps
Cross-section were then applied to solid-state battery stacks in the RAISE Project
