Structural and electrochemical evolution of O3-type NaCu0.2Mn0.2Fe0.2Ni0.2M0.2O2 (M = Ti, V, Cr, Zn, and Co) cathodes

Topal A., Naveed A., Maiga A. H., Gouttebaron R., Haider A., ŞAHİNBAY S., ...Daha Fazla

Electrochimica Acta, cilt.573, 2026 (SCI-Expanded, Scopus)

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 573
  • Basım Tarihi: 2026
  • Doi Numarası: 10.1016/j.electacta.2026.149437
  • Dergi Adı: Electrochimica Acta
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
  • Anahtar Kelimeler: High entropy oxide, Layered structure, Na-ion, O3-type cathode
  • İnönü Üniversitesi Adresli: Evet

Özet

We produced NaCu0.2Mn0.2Fe0.2Ni0.2M0.2O2 cathodes, where M = Ti, V, Cr, Zn, or Co, using a solid-state synthesis technique. We choose NaCu0.2Mn0.2Fe0.2Ni0.2M0.2O2 as the base composition due to synergistic properties of the elements originates from their differences in ionic radii and valance states. According to the structural analysis, V, Cr, and Zn in the samples induce O3/P2 phase competition and the formation of inactive impurities such as ZnO and Na2TMO4. On the other hand, Ti doping shows a single phase O3 structure with R-3 m symmetry. Co-doping yields O3 + minor orthorhombic phase competition without other impurity phases. Rietveld refinements show the V, Cr, Zn doped samples have 30.1, 34.6 and 30.6% O3-phase but Co and Ti doping cause substantial increase in the phase fraction of the\ O3 structure as 78.8 and 100%, respectively. The electrochemical properties of the cathodes in half-cell configuration, investigated using EIS, CV, and galvanostatic measurements, indicate a clear correlation with the secondary phases depending on the last doping element. The single O3 phase (Ti-doped) has worse capacity than O3/P2 mixed phase (Co-doped) cells as 95.1 mAh/g with capacity retention of 50.5% and 103.7 mAh/g with capacity retention of 77.4%, respectively. We calculated the lattice Na content by using the 003 and 104 peaks in the XRD patterns. A correlation between the Na content and the capacity of the O3-type structure depending on the phase ratio of the O3-phase was determined using phase ratios obtained from Rietveld-refinement.