Sodium Peroxide Dihydrate or Sodium Superoxide: The Importance of the Cell Configuration for Sodium–Oxygen Batteries

Abstract

In sodium–oxygen (Na–O2) batteries, multiple discharge products have been observed by different research groups. Given the fact that different materials, gas supplies, and cell configurations are used by different groups, it is a great challenge to draw a clear conclusion on the formation of the different products. Here, two different cell setups are used to investigate the cell chemistries of Na–O2 batteries. With the same materials and gas supplies, a peroxide‐based product is observed in a glass chamber cell and a superoxide‐based product is observed in a stainless‐steel cell. Ex situ high‐energy X‐ray diffraction (HEXRD) and Raman spectroscopy are performed to investigate the structure and composition of the product. In addition, in situ XRD is used to investigate the structure evolution of the peroxide‐based product. The findings highlight the importance of the cell design and emphasize the critical environment of the formation of the discharge products of Na–O2 batteries.

Controlling the Three‐Phase Boundary in Na–Oxygen Batteries: The Synergy of Carbon Nanofibers and Ionic Liquid

“…[33] The second area where the sodium superoxide (NaO 2 )b and should appear is around 1156 cm À1 ,a nd this is not clearly detected.T herefore, the Ramans pectra corresponding to the discharge products for CNF-140a nd CNF-240 cannotc orroborate the generation of NaO 2 . However,t he peak is more prominent in the case of CNF-240, whereas only as mall peak can be seen in CNF-140.…”

“…However,t he peak is more prominent in the case of CNF-240, whereas only as mall peak can be seen in CNF-140. [33] The second area where the sodium superoxide (NaO 2 )b and should appear is around 1156 cm À1 ,a nd this is not clearly detected.T herefore, the Ramans pectra corresponding to the discharge products for CNF-140a nd CNF-240 cannotc orroborate the generation of NaO 2 .…”

Alkali‐Oxygen Batteries Based on Reversible Superoxide Chemistry

“…Therefore, results tend to vary from lab to lab. For example, a case study of two different cells revealed consistently different discharge products . In the assembly, all materials and electrolytes were identical between the two cells and exhibited the same water content.…”

“…In the assembly, all materials and electrolytes were identical between the two cells and exhibited the same water content. In spite of this, one cell produced exclusively NaO 2 and the other produced Na 2 O 2 ⋅ 2 H 2 O . In order to improve reproducibility of results within the field we recommend a full cell design be included in the supporting information of the manuscript, along with the part numbers of any commercial parts used in fabrication.…”

“…For example, ac ase study of two different cells revealed consistently different discharge products. [30] In the assembly,a ll materials and electrolytes were identical between the two cells and exhibited the same water content. In spite of this, one cell produced exclusively NaO 2 and the other produced Na 2 O 2 ·2H 2 O.…”