Intermetallic SnSb nanodots embedded in carbon nanotubes reinforced nanofabric electrodes with high reversibility and rate capability for flexible Li-ion batteries.

Tin (Sn) based anode materials have been regarded as promising alternatives for graphite in lithium ion batteries (LIBs) due to their high theoretical specific capacity and conductivity. However, their practical application is severely restrained by the drastic volume variation during cycling processes. Here we report the preparation of intermetallic SnSb nanodots embedded in carbon nanotube reinforced N-doped carbon nanofibers (SnSb-CNTs@NCNFs) as a free-standing and flexible anode for LIBs. In this unique structure, the SnSb nanodots are well protected by the NCNFs and exhibit greatly reduced volume change. The mechanical strength and conductivity of the nanofabric electrode are further improved by the embedded CNTs. Benefiting from these advantages, the SnSb-CNTs@NCNFs anode delivers a high reversible capacity of 815 mA h g-1 at 100 mA g-1, a high rate capability (370 mA h g-1 at 5000 mA g-1) and a long cycle life (451 mA h g-1 after 1000 cycles at 2000 mA g-1). When assembled into flexible pouch cells, the full cells based on SnSb-CNTs@NCNFs anodes also exhibit high flexibility and good lithium storage performances.