Sodium storage in hard carbon with curved graphene platelets as the basic structural units

Abstract

The mechanism of sodium storage in hard carbon has been revealed by in situ transmission electron microscopy.

Self-supported binder-free hard carbon electrodes for sodium-ion batteries: insights into their sodium storage mechanisms

“…It is known that stage I to IV Na-GICs are not stable 51 and have never been observed, but higher stage compounds, such as NaC64 (stage VIII), have been proposed 52 . Moreover, a very recent study published by Wang et al 53 To further highlight this process, we plotted the compilation of the diffractograms in Figure 8b, where a shoulder is clearly visible. Furthermore, it is clear that once the sodiation starts, the intensity of the (002) peak decreases progressively (Figure 8c (0.4 V), Na plating cannot thermodynamically occur, as reported is several papers 28,54,55 , deposition being possible only bellow 0V.…”

Electrolyte‐Dependent Sodium Ion Transport Behaviors in Hard Carbon Anode

“…Considering the higher working voltage, the defective surfaces are regarded as mono‐vacancies, divacancies, stone‐wales defects, and extreme curvatures in poly‐hexagonal carbon sheets because the localized defect sites can effectively store extra electrons in a more energetically favorable state with binding of a sodium ion. [ 48 ] In the Raman spectra results, L a values of the HC series samples were gradually decreased with reduction of heating temperature from 6.3 to 2.0 nm, supporting the relationship between defective surface and sloping capacity. A relationship between I D / I G values and sloping capacities was confirmed in the HC series samples as shown in Figure S5 (Supporting Information).…”

Template‐free synthesis of novel hollow carbon nanospheres with dual active sites as catalyst for fuel cell cathode to improve oxygen reduction reaction performances

“…39 No other peaks are observed for the HCN-FNFCG-450, besides the broad peak of graphitic structure, the peaks of (002) and (220) from FeC 3 and the peak of (110) from FeN 4 , which indicate that thermal decomposition temperature of precursors has played a very important role for the formation To further investigate the defect sites of carbon structure, Raman spectroscopy was carried out for the synthesized samples. 42 Values of I D /I G for all HCN-FNFCG samples are larger than that of GO. 40,41 The G band is appointed to the vibration of graphitic carbon, and the D band is corresponding to the disordered carbon structure.…”

“…A higher value of I D /I G ratio is usually ascribed to a lower degree of graphitization. 42 Values of I D /I G for all HCN-FNFCG samples are larger than that of GO. The larger value for I D /I G ratio reveals that degree of disordered structures for carbon are higher in the HCN-FNFCG samples.…”