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SUMMARY:Exploring the Surface of Vanadium Phosphate Cathode Materials
DTSTART;VALUE=DATE-TIME:20211125T073100Z
DTEND;VALUE=DATE-TIME:20211125T073200Z
DTSTAMP;VALUE=DATE-TIME:20260306T082803Z
UID:indico-contribution-4193@events01.synchrotron.org.au
DESCRIPTION:Speakers: Tristram Jenkins (Queensland University of Technolog
 y)\nIn this study\, we used a combination of synchrotron soft X-ray absorp
 tion spectroscopy (XAS)\, lab-scale experimental techniques and first prin
 ciples computation to critically examine and validate the surface and bulk
  electronic structure of prototypical vanadium (III) phosphate intercalati
 on cathode materials\, Na3V2(PO4)3\, Li3V2(PO4)3 and K3V3(PO4)4• H2O.  U
 sing a combination of XPS\, Raman UV-Vis -NIR\, UPS and DFT calculations\,
  a full picture of each AVPs electronic structure was developed and valida
 ted using both experimental and calculated electronic structure and densit
 y of states data. From our synchrotron data\, XAS fluorescence yield and e
 lectron yield measurements reveal substantial variation in surface-to-bulk
  atomic structure\, vanadium oxidation states and density of oxygen hole s
 tates across all AVP samples. We attribute this variation to an intrinsic 
 alkali metal surface depletion layer identified across these alkali metal 
 vanadium (III) phosphates. We propose that an alkali-depleted surface prov
 ides a beneficial interface with the bulk structure(s) that raises the Fer
 mi level and improves surface charge transfer kinetics at the surface of t
 his family of materials. This surface depletion phenomenon has been previo
 usly reported in other prominent transition metal phosphate intercalation 
 cathodes\, such as LiFePO4 and its general presence here suggests wider ub
 iquity amongst alkali transition metal phosphate materials.\n\nhttps://eve
 nts01.synchrotron.org.au/event/146/contributions/4193/
LOCATION:Online
URL:https://events01.synchrotron.org.au/event/146/contributions/4193/
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