Complementary stabilization by core/sheath carbon nanofibers/spongy carbon on submicron tin oxide particles as anode for lithium-ion batteries

To limit the pulverization of tin-based anode materials during lithiation/delithiation, submicron tin oxide/tin particles are fixed on core/sheath carbon nanofiber/spongy carbon via hydrothermal and carbothermal reduction treatment in this work. During carbothermal reduction, SnO2 nanosheets are converted to spherical Sn submicron particles and simultaneously the hollow spongy carbon is produced and still enwrap on carbon nanofiber. The as-produced flexible film is used for a binder-free anode for lithium ion batteries, without the polymer binder and conductive carbon. At 0.1, 0.5, 1 and 2 A g-1, the composite electrode respectively displays a discharging capacity of 1393.0, 738.2, 583.6 and 382.6 mAh g-1. Moreover, it delivers specific capacity of 726.9 mAh g-1 and coulombic efficiency of 99.45 % after 300 cycles at 0.1 A g-1. The comparison sample of carbon nanofiber/SnOx film without the presence of spongy carbon displays much lower rate performance and worse cyclic performance. The integrated structure of carbon nanofiber/SnOx/spongy carbon results in the remarkable Li-storage performance, in which the carbon nanofiber and spongy carbon synergistically provide conductive channel and buffer zone to hinder the pulverization and peeling of SnOx particles during charging-discharging processes.