Amorphous carbon layer contributing Li storage capacity to Nb2O5@C nanosheetsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra05935f

In this work, amorphous carbon very thin layers coated on a Nb 2 O 5 nanosheet flexible composite have been successfully synthesized. The composite delivers a discharge capacity of 396 mA h g −1 after 100 cycles at a current density of 100 mA g −1 , which is very much higher than for bare Nb 2 O 5 nanosheets. The high-capacity of Nb 2 O 5 nanosheets has been successfully realized through introducing amorphous carbon layers, which have been demonstrated to have a large capacity owing to the existence of defects on amorphous carbon layers.