Chapter 4
Cathodic Exfoliation of Graphite
in Molten Salt Electrolytes
Abstract Scalable green production of carbon nanomaterials with enhanced physical, chemical and mechanical properties has been an interesting, yet challenging
topic. Cathodic exfoliation of graphite in molten salt electrolytes has provided an
efficient approach for economic and environmentally sustainable production of highquality carbon nanostructures, including carbon nanotubes, carbon nanoparticles,
graphene and nanoparticles encapsulated in graphitic shells. The structure and morphology of these carbon nanostructures depend on a variety of parameters including
the reactor design, the chemical composition of the molten salt, the atmosphere and
the characteristics of the carbon raw material as well as the electrochemical parameters such as the voltage and the current density applied. This chapter provides an
overview of the key parameters that influence the cathodic exfoliation behavior of
graphite in molten salts.
Keywords Graphite · Molten salts · Cathodic exfoliation · Graphene · Carbon
nanotubes · Nanoparticles · Encapsulation
Over the last 20 years or so, a recent family of molten salt technologies has been
advanced for the large-scale preparation of high-quality carbon nanostructures for
diverse applications. The fundamental features of these molten salt methods are
briefed in Figs. 4.1 and 4.2, showing that varying nanostructured carbons are able
to be fabricated by the treatment of nearly indistinguishable graphite raw materials,
yet under dissimilar conditions, i.e., the lack or presence of an electric potential,
and additionally the chemical composition of the surrounding atmosphere above the
melt. Graphite is able to be exfoliated into differing carbon nanostructures in the LiCl
melt. Figure 4.1 presents the SEM/TEM morphologies of the graphite feed material
used as the carbon source and those of carbon products that can be manufactured
under different processing conditions. Figure 4.2 displays the electrochemical cell
developed for the molten salt preparation of varying nanostructured carbon materials
at a scale of several hundreds of grams producible on a single run.
It was discussed in Chap. 3 that the corrosion of polycrystalline synthetic graphite
in LiCl melt underneath an air atmosphere can lead to the formation of carbon
nanostructures which include exfoliated carbon flakes, graphene nanosheets, pitted
© Springer Nature Singapore Pte Ltd. 2020
A. R. Kamali, Green Production of Carbon Nanomaterials in Molten Salts
and Applications, https://doi.org/10.1007/978-981-15-2373-1_4
37
Cathodic Exfoliation of Graphite
in Molten Salt Electrolytes
Abstract Scalable green production of carbon nanomaterials with enhanced physical, chemical and mechanical properties has been an interesting, yet challenging
topic. Cathodic exfoliation of graphite in molten salt electrolytes has provided an
efficient approach for economic and environmentally sustainable production of highquality carbon nanostructures, including carbon nanotubes, carbon nanoparticles,
graphene and nanoparticles encapsulated in graphitic shells. The structure and morphology of these carbon nanostructures depend on a variety of parameters including
the reactor design, the chemical composition of the molten salt, the atmosphere and
the characteristics of the carbon raw material as well as the electrochemical parameters such as the voltage and the current density applied. This chapter provides an
overview of the key parameters that influence the cathodic exfoliation behavior of
graphite in molten salts.
Keywords Graphite · Molten salts · Cathodic exfoliation · Graphene · Carbon
nanotubes · Nanoparticles · Encapsulation
Over the last 20 years or so, a recent family of molten salt technologies has been
advanced for the large-scale preparation of high-quality carbon nanostructures for
diverse applications. The fundamental features of these molten salt methods are
briefed in Figs. 4.1 and 4.2, showing that varying nanostructured carbons are able
to be fabricated by the treatment of nearly indistinguishable graphite raw materials,
yet under dissimilar conditions, i.e., the lack or presence of an electric potential,
and additionally the chemical composition of the surrounding atmosphere above the
melt. Graphite is able to be exfoliated into differing carbon nanostructures in the LiCl
melt. Figure 4.1 presents the SEM/TEM morphologies of the graphite feed material
used as the carbon source and those of carbon products that can be manufactured
under different processing conditions. Figure 4.2 displays the electrochemical cell
developed for the molten salt preparation of varying nanostructured carbon materials
at a scale of several hundreds of grams producible on a single run.
It was discussed in Chap. 3 that the corrosion of polycrystalline synthetic graphite
in LiCl melt underneath an air atmosphere can lead to the formation of carbon
nanostructures which include exfoliated carbon flakes, graphene nanosheets, pitted
© Springer Nature Singapore Pte Ltd. 2020
A. R. Kamali, Green Production of Carbon Nanomaterials in Molten Salts
and Applications, https://doi.org/10.1007/978-981-15-2373-1_4
37