Does carbon coating really improves the electrochemical performance of electrospun SnO₂ anodes?

In this paper, we report the influence of carbon coating on the electrochemical performance of hollow structured SnO₂ electrospun nanofibers. The electrospun nanofibers are subjected to plasma enhanced chemical vapour deposition for a conformal carbon coating of ∼6 nm thickness without destroying the one dimensional morphological features of the fiber mats. Li-storage properties are evaluated in half-cell configuration between two different potential windows i.e. 0.005-0.8 V and 0.005-2.5 V vs. Li. The potential regions tested corresponds to the alloying/de-alloying and alloying/de-alloying & conversion reactions for former and latter cases, respectively. Very high reversibility over 3.6 moles of Li is feasible for both bare and carbon coated SnO₂, without an obvious difference between the electrochemical profiles noted during cycling. In contrary, huge differences in the electrochemical performances are observed for bare and carbon coated SnO2 when the test cell is cycled for conversion reaction. This result clearly shows the importance of carbon coating for conversion reaction compared to alloying/de-alloying reaction.