High-Entropy Co-Free O3-Type Layered Oxyfluoride: A Promising Air-Stable Cathode for Sodium-Ion Batteries

Akanksha Joshi, Sankalpita Chakrabarty, Sri Harsha Akella, Arka Saha, Ayan Mukherjee, Bruria Schmerling, Michal Ejgenberg, Rosy Sharma, Malachi Noked

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Sodium-ion batteries have recently emerged as a promising alternative to lithium-based batteries, driven by an ever-growing demand for electricity storage systems. The present workproposes a cobalt-free high-capacity cathode for sodium-ion batteries, synthesized using a high-entropy approach. The high-entropy approach entails mixing more than five elements in a single phase; hence, obtaining the desired properties is a challenge since this involves the interplay between different elements. Here, instead of oxide, oxyfluoride is chosen to suppress oxygen loss during long-term cycling. Supplement to this, lithium is introduced in the composition to obtain high configurational entropy and sodium vacant sites, thus stabilizing the crystal structure, accelerating the kinetics of intercalation/deintercalation, and improving the air stability of the material. With the optimization of the cathode composition, a reversible capacity of 109 mAh g−1 (2–4 V) and 144 mAh g−1 (2–4.3 V) is observed in the first few cycles, along with a significant improvement in stability during prolonged cycling. Furthermore, in situ and ex situ diffraction studies during charging/discharging reveal that the high-entropy strategy successfully suppresses the complex phase transition. The impressive outcomes of the present work strongly motivate the pursuit of the high-entropy approach to develop efficient cathodes for sodium-ion batteries.

Original languageEnglish
Article number2304440
JournalAdvanced Materials
Volume35
Issue number51
DOIs
StatePublished - 21 Dec 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.

Keywords

  • O3-layered structure
  • air stability
  • cobalt-free cathodes
  • cocktail effect
  • high configuration entropy
  • sodium-ion batteries

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