Synergistic PF6− and FSI intercalation enables stable graphite cathode for potassium-based dual ion battery

Hong Tan, Dengyun Zhai, Feiyu Kang, Biao Zhang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)

Abstract

Potassium-based dual ion batteries have emerged as promising alternatives to the prevailing lithium-ion batteries due to the advantages in cost and sustainability. Single-anion intercalation into graphite takes place on the cathode side, but it usually delivers a low capacity with poor Coulombic efficiency in potassium-based systems. We demonstrate the performance could be significantly boosted through synergistic dual-anion intercalation of FSI and PF6. The presence of PF6 helps the formation of an effective cathode electrolyte interface to allow high anionic stability up to 5.5 V, while FSI intercalation brings about superior rate capability and long-term cyclic stability. Concurrent intercalation of FSI and PF6 is tracked by in-situ Raman spectroscopy and ex-situ XRD. It reveals the formation of stage I graphite intercalation compounds (GICs) upon charging, leading to a reversible capacity of over 100 mAh g−1 with an average potential of 4.65 V (vs. K+/K). Furthermore, the graphite-potassium cell delivers an exceptional capacity of 94 mAh g−1 at 0.3 A g−1 and shows capacity retention of 96% after 250 cycles. The strategy provides a novel avenue toward stable dual-ion battery via intercalation chemistry regulation.

Original languageEnglish
Pages (from-to)363-370
Number of pages8
JournalCarbon
Volume178
DOIs
Publication statusPublished - 30 Jun 2021

Keywords

  • Anion intercalation
  • Dual ion batteries
  • Graphite cathode
  • In-situ Raman

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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