4.7 Encapsulation of Li 2 CO 3 Nanocrystals in Carbon Layers
57
As a conclusion, the mechanism involved in this process can be explained as
follows: The occurrence of the reaction (4.1) at 800 °C leads to the formation of
Li 2 CO 3 dissolved in the LiCl melt. As the temperature decreased, the solubility
of Li 2 CO 3 in melt reduces, causing the nucleation of Li 2 CO 3 crystallites. These
crystallites can grow in size with further temperature reduction. The nanosingle
crystals of Li 2 CO 3 formed are capable of being encapsulated into carbon cages to
fabricate the hybrid nanostructure material observed in Fig. 4.15e. Such a hybrid
material can be used for the fabrication of nanodiamonds at an ambient external
pressure.
It is worth mentioning that various techniques have been used in the literature in
order to encapsulate nanoparticles such as Fe 2 O 3 [54], LiFePO 4 [55], Si [56], MgO
[57], W 2 C [58], GdC 2 [59] and Cu [60] in carbon layers for use in Li-ion batteries
[54–57] and other functional applications. These methods often employ carboncontaining precursors and involve energy-intensive high-temperature steps including
spray drying–carbonization–oxidation [54], aerosol processing using graphene oxide
[56], combustion synthesis [57], reduction of graphite intercalation compounds [60]
or arc discharge processing [59]. The molten salt method discussed in this chapter
can be considered as an efficient approach for one-pot encapsulation of nanoparticles.
References
1. A. Rezaei, A.R. Kamali, Green production of carbon nanomaterials in molten salts, mechanisms
and applications. Diam. Relat. Mater. 83, 146–161 (2018)
2. A.R. Kamali, D.J. Fray, Molten salt corrosion of graphite as a possible way to make carbon
nanostructures. Carbon 56, 121–131 (2013)
3. A.R. Kamali, D.J. Fray, Towards large scale preparation of carbon nanostructures in molten
LiCl. Carbon 77, 835–845 (2014)
4. A.R. Kamali, D.J. Fray, Large-scale preparation of graphene by high temperature diffusion of
hydrogen in graphite. Nanoscale 7, 11310–11320 (2015)
5. A.R. Kamali, Eco-friendly production of high quality low cost graphene and its application in
lithium ion batteries. Green Chem. 18, 1952–1964 (2016)
6. A.R. Kamali C. Schwandt, D. J. Fray, Effect of the graphite electrode material on the
characteristics, Mater. Charact. 62, 987–994 (2011)
7. A.R. Kamali, D.J. Fray, Electrochemical interaction between graphite and molten salts to
produce nanotubes, nanoparticles, graphene and nanodiamonds. J. Mater. Sci. 51, 569–576
(2016)
8. A.R. Kamali, G. Divitini, C. Schwandt, D.J. Fray, Correlation between microstructure and
thermokinetic characteristics of electrolytic carbon nanomaterials. Corr. Sci. 64, 90–97 (2012)
9. D.J. Fray, A.R. Kamali, Method of producing Graphene, UK Patent GB 2523154
10. I.A. Novoselova, S.V. Kuleshov, S.V. Volkov, V.N. Bykov, Electrochemical synthesis, morphological and structural characteristics of carbon nanomaterials produced in molten salts.
Electrochim. Acta 211, 343–355 (2016)
11. J.B. Bai, A. Lhamon, A. Marraud, B. Juffrey, V. Zymla, Synthesis of SWNTs and MWNTs by
a molten salt (NaCl) method. Chem. Phys. Lett. 365, 184–188 (2002)
12. A.R. Kamali, H.K. Kim, K. Kim, R.V. Kumar, D.J. Fray, Large scale green production of
ultra-high capacity anode consisting of graphene encapsulated silicon nanoparticles. J. Mater.
Chem. A 5, 19126–19135 (2017)
57
As a conclusion, the mechanism involved in this process can be explained as
follows: The occurrence of the reaction (4.1) at 800 °C leads to the formation of
Li 2 CO 3 dissolved in the LiCl melt. As the temperature decreased, the solubility
of Li 2 CO 3 in melt reduces, causing the nucleation of Li 2 CO 3 crystallites. These
crystallites can grow in size with further temperature reduction. The nanosingle
crystals of Li 2 CO 3 formed are capable of being encapsulated into carbon cages to
fabricate the hybrid nanostructure material observed in Fig. 4.15e. Such a hybrid
material can be used for the fabrication of nanodiamonds at an ambient external
pressure.
It is worth mentioning that various techniques have been used in the literature in
order to encapsulate nanoparticles such as Fe 2 O 3 [54], LiFePO 4 [55], Si [56], MgO
[57], W 2 C [58], GdC 2 [59] and Cu [60] in carbon layers for use in Li-ion batteries
[54–57] and other functional applications. These methods often employ carboncontaining precursors and involve energy-intensive high-temperature steps including
spray drying–carbonization–oxidation [54], aerosol processing using graphene oxide
[56], combustion synthesis [57], reduction of graphite intercalation compounds [60]
or arc discharge processing [59]. The molten salt method discussed in this chapter
can be considered as an efficient approach for one-pot encapsulation of nanoparticles.
References
1. A. Rezaei, A.R. Kamali, Green production of carbon nanomaterials in molten salts, mechanisms
and applications. Diam. Relat. Mater. 83, 146–161 (2018)
2. A.R. Kamali, D.J. Fray, Molten salt corrosion of graphite as a possible way to make carbon
nanostructures. Carbon 56, 121–131 (2013)
3. A.R. Kamali, D.J. Fray, Towards large scale preparation of carbon nanostructures in molten
LiCl. Carbon 77, 835–845 (2014)
4. A.R. Kamali, D.J. Fray, Large-scale preparation of graphene by high temperature diffusion of
hydrogen in graphite. Nanoscale 7, 11310–11320 (2015)
5. A.R. Kamali, Eco-friendly production of high quality low cost graphene and its application in
lithium ion batteries. Green Chem. 18, 1952–1964 (2016)
6. A.R. Kamali C. Schwandt, D. J. Fray, Effect of the graphite electrode material on the
characteristics, Mater. Charact. 62, 987–994 (2011)
7. A.R. Kamali, D.J. Fray, Electrochemical interaction between graphite and molten salts to
produce nanotubes, nanoparticles, graphene and nanodiamonds. J. Mater. Sci. 51, 569–576
(2016)
8. A.R. Kamali, G. Divitini, C. Schwandt, D.J. Fray, Correlation between microstructure and
thermokinetic characteristics of electrolytic carbon nanomaterials. Corr. Sci. 64, 90–97 (2012)
9. D.J. Fray, A.R. Kamali, Method of producing Graphene, UK Patent GB 2523154
10. I.A. Novoselova, S.V. Kuleshov, S.V. Volkov, V.N. Bykov, Electrochemical synthesis, morphological and structural characteristics of carbon nanomaterials produced in molten salts.
Electrochim. Acta 211, 343–355 (2016)
11. J.B. Bai, A. Lhamon, A. Marraud, B. Juffrey, V. Zymla, Synthesis of SWNTs and MWNTs by
a molten salt (NaCl) method. Chem. Phys. Lett. 365, 184–188 (2002)
12. A.R. Kamali, H.K. Kim, K. Kim, R.V. Kumar, D.J. Fray, Large scale green production of
ultra-high capacity anode consisting of graphene encapsulated silicon nanoparticles. J. Mater.
Chem. A 5, 19126–19135 (2017)