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.