In Situ-Formed Cr₂O₃ Coating on NaCrO₂ with Improved Sodium Storage Performance

Abstract

Cr 2 O 3 is generally considered as an impurity phase with negative effects on the electrochemical performance of NaCrO 2 because it may cause a certain degree of capacity loss. In this study, however, we have found the bright side of Cr 2 O 3 as a protective coating material, which greatly improves the Na + storage capability, especially the cycling stability, of NaCrO 2 . After 1000 cycles at 10C, a capacity of 100.4 mAh g −1 with a high capacity retention of 84.8% can be achieved for a Cr 2 O 3coated NaCrO 2 sample. The optimal sample exhibits a rate performance with 108.0 mAh g −1 at a high rate of 60C. Cyclic voltammetry analysis indicates that such an in situ-formed inactive Cr 2 O 3 layer has little influence on Na + diffusion in NaCrO 2 electrodes, but it prevents the direct contact between the active material and the electrolyte, suppressing the side reactions effectively.

Sodium ion intercalation and multi redox behavior of a Keggin type polyoxometalate during [PMo10V2O40]5−to [PMo10V2O40]27−as a cathode material for Na-ion rechargeable batteries

“…Due to the larger ionic radius of Na + , rather than 22 Na + ions, only 12 sodium ions are intercalated in the intercluster cavities. 18 During the discharge process the Na-POM experiences huge volume expansion as a result of sodium ion intercalation in the intercluster cavities. In the DFT studies, the geometry of the Na-POM and its intercluster interaction in charged and super reduced states ( i.e.…”

“…[14][15][16][17] In the line of replicating the commercial LiCoO 2 , NaCoO 2 paves the way in the NIB cathode chemistry with an increased specic capacity of 121 mA h g À1 at 0.1C rate. 18 However, the latter undergoes numerous phase transitions during cycling, which leads to poor reversibility. Polyanionic frameworks comprise Na 3 M 2 (XO 4 ) 3 (where M ¼ V, Fe, Mn, Ti, etc.…”

Self-Template Synthesis of NaCrO2 Submicrospheres for Stable Sodium Storage

“…The structures of NaCrO 2 samples were characterized by employing the strategies that had been described in our previous work . The X-ray diffraction (XRD) patterns for Rietveld refinements were conducted at 2° min –1 .…”

“…The electrochemical properties of NaCrO 2 samples were tested in coin-type cells (CR2032). The assembling process was the same as our last work . The mass loading of the active material was 1.0–2.0 mg cm –2 .…”

“…The mass loading of the active material was 1.0–2.0 mg cm –2 . For the full cell, Sb/C was employed as the anode, which was prepared according to our previous work , with a mass loading of around 1.0 mg cm –2 . Before assembling the full cell, the anode was presodiated in a half-cell at 0.1 A g –1 for several cycles to form a stable SEI film and reduce the irreversible capacity in full cells, with the presodiated process end at the half-discharge state.…”