A Co- and Ni-Free P2/O3 Biphasic Lithium Stabilized Layered Oxide for Sodium-Ion Batteries and its Cycling Behavior

Liangtao Yang, Juan Miguel López del Amo, Zulipiya Shadike, Seong Min Bak, Francisco Bonilla, Montserrat Galceran, Prasant Kumar Nayak, Johannes Rolf Buchheim, Xiao Qing Yang, Teófilo Rojo, Philipp Adelhelm

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86 Scopus citations

Abstract

Cobalt- and nickel-free cathode materials are desirable for developing low-cost sodium-ion batteries (SIBs). Compared to the single P-type and O-type structures, biphasic P/O structures become a topic of interest thanks to improved performance. However, the added complexity complicates the understanding of the storage mechanism and the phase behavior is still unclear, especially over consecutive cycling. Here, the properties of biphasic P2(34%)/O3(60%) Na0.8Li0.2Fe0.2Mn0.6O2 and its behavior at different states of charge/discharge are reported on. The material is composed of single phase O3 and P2/O3 biphasic particles. Sodium occupies the alkali layers, whereas lithium predominantly (95%) is located in the transition metal layer. An initial reversible capacity of 174 mAh g-1 is delivered with a retention of 82% dominated by Fe3+/Fe4+ along with contributions from oxygen and partial Mn3+/4+ redox. Cycling leads to complex phase transitions and ion migration. The biphasic nature is nevertheless preserved, with lithium acting as the structure stabilizer.

Original languageEnglish
Article number2003364
JournalAdvanced Functional Materials
Volume30
Issue number42
DOIs
StatePublished - 1 Oct 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 The Authors. Published by Wiley-VCH GmbH

Keywords

  • energy storage
  • layered oxides
  • positive electrode materials
  • sodium ion batteries

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