Investigations of the capacity fading mechanism of Na(0.44)MnO(2)via ex situ XAS and magnetization measurements

ALTIN S., OZ E., ALTIN E., DEMIREL S., BAYRİ A., AVCI S.

DALTON TRANSACTIONS, cilt.47, sa.47, ss.17102-17108, 2018 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 47 Sayı: 47
  • Basım Tarihi: 2018
  • Doi Numarası: 10.1039/c8dt03508c
  • Dergi Adı: DALTON TRANSACTIONS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.17102-17108
  • İnönü Üniversitesi Adresli: Evet

Özet

Na-ion batteries represent a promising complementary alternative to Li-ion batteries due to their high energy density and natural abundancy of Na. However, these batteries have short cycle life and extensive research activities on these batteries are required to understand the mechanism of such drawbacks. In this report, we investigate the capacity fading mechanism of Na(0.44)MnO(2)via ex situ X-ray diffraction, X-ray absorption spectroscopy, Fourier transform infrared spectroscopy and magnetization measurements. Our results show that the unit cell volume, the effective mass of Mn-O bonds, the number of Mn4+ ions and the effective magnetic moment decrease upon repeated cycling. We propose that some Mn4+ ions in the octahedral environment become Mn3+ ions in a square pyramidal environment, causing oxygen release upon cycling. Any free oxygen in the battery is expected to react with the electrolyte and cause capacity fade.