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Combustion-synthesized sodium manganese (cobalt) oxides as cathodes for sodium ion batteries

Research output: Contribution to journalJournal article

Published
  • Nicolas Bucher
  • Steffen Hartung
  • Irina Gocheva
  • Yan L. Cheah
  • Madhavi Srinivasan
  • Harry E. Hoster
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<mark>Journal publication date</mark>07/2013
<mark>Journal</mark>Journal of Solid State Electrochemistry
Issue number7
Volume17
Number of pages7
Pages (from-to)1923-1929
Publication statusPublished
Original languageEnglish

Abstract

We report on the electrochemical properties of layered manganese oxides, with and without cobalt substituents, as cathodes in sodium ion batteries. We fabricated sub-micrometre-sized particles of Na0.7MnO2 + z and Na0.7Co0.11Mn0.89O2 + z via combustion synthesis. X-ray diffraction revealed the same layered hexagonal P2-type bronze structure with high crystallinity for both materials. Potentiostatic and galvanostatic charge/discharge cycles in the range 1.5-3.8 V vs. Na | Na+ were performed to identify potential-dependent phase transitions, capacity, and capacity retention. After charging to 3.8 V, both materials had an initial discharge capacity of 138 mA h g(-1) at a rate of 0.3 C. For the 20th cycle, those values reduced to 75 and 92 mA h g(-1) for Co-free and Co-doped samples, respectively. Our findings indicate that earlier works probably underestimated the potential of (doped) P2-type Na0.7MnO2 + z as cathode material for sodium ion batteries in terms of capacity and cycle stability. Apart from doping, a simple optimization parameter seems to be the particle size of the active material.