The wide range of applications for graphite, including energy storage, catalysis and sensor technology, makes it an important area of research. However, transferring these results from fundamental research to application still requires significant efforts. Production issues can be a barrier to translating fundamental findings. Some of these include the synthesizing of pure, uniform and macroporous Graphite as well the characterization or the electrode surface. SEM or EDX advanced microscopy can overcome them. In this article, a SEM (Zeiss) microscope with an integrated EDX system was used at the Uppsala Fab Lab to analyze graphite electrodes and to detect polymer.
The cyclic voltammograms CV of bare graphite GE in 0.5 M NaOH showed that the cathodic peak CI does not appear in the potential range up to and including E = 0.7 V. This observation is due to the fact that this region does not favour the sluggish diffusion controlled oxygen reduction reaction, ORR. The peak observed in the forward span can be attributed to water molecule reduction.
To improve the electrode response of graphite, we prepared electrodes with different binder types. The samples were cast from a mixture of 90 w/w graphite powder (MTI Corp.) and 10 w/w of PVDF or CMC binder. The CMC binding resulted a lower oxygen permeability than PVDF. The lower permeability may be attributed the formation of a surface layer of carbonate due to desodiation.
In addition, EN was added to the mixture and resulted a significant decrease in electrode breathing when intercalating solvated ions of sodium. The effect was analyzed by EIS. The EIS data show that the addition of EN reduces the expansion of the graphite during cycling by more than half.
It is also shown how kinetics can explain the asymmetrical behaviors of the electrode graphite when cycling. As shown by the voltage-hysteresis plots in Fig. S9. The 15% GDE PE shows a capacitive and mixed behavior, with the Warburg line. 0.9).
The EIS data also reveal that the electrodes can be divided into two distinct regions according to the presence of intrinsic (inherent) oxygen and adsorbed oxygen. In highly anodic conditions, sufficient amounts of inner (inner) oxygen are generated on the GE's surface and captured into its pores. OxSFG is the name of this oxide. At low anodic potentials, graphite is oxidized to produce external oxygen by dissolved oxygen. This oxygen diffuses from the graphite's outer pores into the carbon lattice matrix where it is reduced to a water.
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