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  • Aktekin, BurakUppsala universitet,Strukturkemi (författare)

Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO) : In Situ Neutron Diffraction and Performance in Li Ion Full Cells

  • Artikel/kapitelEngelska2019

Förlag, utgivningsår, omfång ...

  • 2019-05-03
  • AMER CHEMICAL SOC,2019
  • printrdacarrier

Nummerbeteckningar

  • LIBRIS-ID:oai:DiVA.org:uu-387975
  • https://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387975URI
  • https://doi.org/10.1021/acsaem.8b02217DOI

Kompletterande språkuppgifter

  • Språk:engelska
  • Sammanfattning på:engelska

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Klassifikation

  • Ämneskategori:ref swepub-contenttype
  • Ämneskategori:art swepub-publicationtype

Anmärkningar

  • Lithium ion cells utilizing LiNi0.5Mn1.5O4 (LNMO) as the positive electrode are prone to fast capacity fading, especially when operated in full cells and at elevated temperatures. The crystal structure of LNMO can adopt a P4(3)32 (cation-ordered) or Fd (3) over barm (disordered) arrangement, and the fading rate of cells is usually mitigated when samples possess the latter structure. However, synthesis conditions leading to disordering also lead to oxygen deficiencies and rock-salt impurities and as a result generate Mn3+. In this study, in situ neutron diffraction was performed on disordered and slightly Mn-rich LNMO samples to follow cation ordering-disordering transformations during heating and cooling. The study shows for the first time that there is not a direct connection between oxygen release and cation disordering, as cation disordering is observed to start prior to oxygen release when the samples are heated in a pure oxygen atmosphere. This result demonstrates that it is possible to tune disordering in LNMO without inducing oxygen deficiencies or forming the rock-salt impurity phase. In the second part of the study, electrochemical testing of samples with different degrees of ordering and oxygen content has been performed in LNMO vertical bar vertical bar LTO (Li4Ti5O12) full cells. The disordered sample exhibits better performance, as has been reported in other studies; however, we observe that all cells behave similarly during the initial period of cycling even when discharged at a 10 C rate, while differences arise only after a period of cycling. Additionally, the differences in fading rate were observed to be time-dependent rather than dependent on the number of cycles. This performance degradation is believed to be related to instabilities in LNMO at higher voltages, that is, in its lower lithiation states. Therefore, it is suggested that future studies should target the individual effects of ordering and oxygen content. It is also suggested that more emphasis during electrochemical testing should be placed on the stability of samples in their delithiated state.

Ämnesord och genrebeteckningar

Biuppslag (personer, institutioner, konferenser, titlar ...)

  • Valvo, MarioUppsala universitet,Strukturkemi(Swepub:uu)marva692 (författare)
  • Smith, Ronald I.Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Source, Harwell Campus, Didcot OX11 0QX, Oxon, England (författare)
  • Sörby, Magnus H.Inst Energy Technol, Dept Neutron Mat Characterizat, POB 40, NO-2027 Kjeller, Norway (författare)
  • Marzano, Fernanda LodiScania CV AB, SE-15187 Sodertalje, Sweden (författare)
  • Zipprich, WolfgangVolkswagen AG, D-38436 Wolfsburg, Germany (författare)
  • Brandell, Daniel,1975-Uppsala universitet,Strukturkemi(Swepub:uu)dbr10334 (författare)
  • Edström, Kristina,Professor,1958-Uppsala universitet,Strukturkemi(Swepub:uu)ked02526 (författare)
  • Brant, WilliamUppsala universitet,Strukturkemi(Swepub:uu)wilbr976 (författare)
  • Uppsala universitetStrukturkemi (creator_code:org_t)

Sammanhörande titlar

  • Ingår i:ACS Applied Energy Materials: AMER CHEMICAL SOC2:5, s. 3323-33352574-0962

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