Solid state synthesis of layered sodium manganese oxide for sodium-ion battery by in-situ high energy X-ray diffraction and X-ray absorption near edge spectroscopy

Abstract

In situ high energy X-ray diffraction (HEXRD) and in situ X-ray absorption near edge spectroscopy (XANES) were carried out to understand the soild state synthesis of Na x MnO 2 , with particular interest on the synthesis of P2 type Na 2/3 MnO 2. It was found that there were multi intermediate phases formed before NaMnO 2 appeared at about 600 o C. And the final product after cooling process is a combination of O'3 NaMnO 2 with P2 Na 2/3 MnO 2. A P2 type Na 2/3 MnO 2 was synthesized at reduced temperature (600 o C). The influence of Na 2 CO 3 impurity on the electrochemical performance of P2 Na 2/3 MnO 2 was thoroughly investigated in our work. It was found that the content of Na 2 CO 3 can be reduced by optimizing Na 2 CO 3 /MnCO 3 ratio during the solid state reaction or other post treatment such as washing with water. We expected our results could provide a good guide for future development of high performance cathode materials for sodium-ion batteries.

P2-Na0.67Mn0.85Al0.15O2 and NaMn2O4 Blend as Cathode Materials for Sodium-Ion Batteries Using a Natural β-MnO2 Precursor

“…During this stage, the total weight loss was 1.2% compared to the literature (∼1 to 1.5%). 23 If Na 0.67 MnO 2 further reacts with Na 2 CO 3 , in theory, the weight loss should be ≥8.6 wt % (i.e., to attain NaMnO 2 ), whereas for the synthesized blend, the recorded weight loss was ∼0.7 wt %, which further confirms the mixed state of the synthesized powder (i.e., Na 0.67 Mn 0.85 Al 0.15 O 2 and NaMn 2 O 4 ). This weight loss can be attributed to the carbon combustion unmasked by other reactions.…”

“…A CV with a scan rate of ±0.025 mV/s projected into well-denoted voltammograms allowed the study of the behavior of electrodes/electrolyte interfaces and charge-transfer reactions. 23 In the GCPL tests, the cells were cycled between 2.0 and 4.0 V versus Na/Na + using various charge/discharge currents. Taking into consideration that each phase has a different theoretical capacity and operating voltages, the currents used were fixed based on the theoretical capacity of the more stable phases, that is, NaMn 2 O 4 .…”

Thermally Activated P2‐O3 Mixed Layered Cathodes toward Synergistic Electrochemical Enhancement for Na Ion Batteries

“…[5][6][7][8][9] Among them, layer-structured oxides exhibit higher capacity and energy density than polyanionic compounds. [10][11][12][13][14][15][16][17][18][19] Layered oxides cathode materials have ≈250 mAh g −1 of theoretical capacity based on a single electron redox of transition metals. The complexity of layered oxides arises from their structural and compositional variation which can diversify their structural arrangement such as O3, P2, and etc.…”

Metal‐Organic‐Framework‐Based Cathodes for Enhancing the Electrochemical Performances of Batteries: A Review

“…Although LIBs are still dominant in many applications, sodium ion batteries (SIBs) are emerging due to their availability in nature source and lower compared to LIBs. SIBs have been regarded as an alternative promising solution for electrical power system . Lithium‐sulfur (Li‐S) batteries, lithium‐air (Li‐O 2 ) batteries and lithium‐selenium (Li‐Se) batteries have been widely exploited to enhance the electrochemical performances of energy storage systems.…”