The role of carbon incorporation in SnO2 nanoparticles for Li rechargeable batteries

Since carbothermal reduction of SnO2 occurs above 600 °C, carbon-coating experiments using various polymer precursors have been carried out at relatively low temperatures (∼500 °C). It is not likely, however, that the carbon synthesized at ∼500 °C much enhances the conductivity of SnO2 anodes, because polymer precursors have undergone insufficient carbonization. This article confirms that the main role of carbon coating is sustaining the domain of each Sn nanoparticle by preventing its aggregation, and thereby improving the cycling performance of SnO2 nanoparticles. The transmission electron microscopy after cycling showing well dispersed Sn nanoparticles and electrochemical impedance spectroscopy revealing larger charge-transfer resistances with increasing carbon contents are in line with these interpretations.

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► Carbon coating synthesized at ∼500 °C does not undergo sufficient carbonization.
► More carbon contents result in higher charge-transfer resistance of C-coated SnO2.
► The main role of carbon in SnO2 is the sustaining of the domain of each Sn nanoparticle.