Amorphous Cu-added/SnOx/CNFs composite webs as anode materials with superior lithium-ion storage capability

Abstract

Amorphous Cu-added tin oxides/carbon nanofiber (Cu-added SnO_x/CNFs) composite webs used for lithium-ion battery anode materials are prepared by an electrospinning technique and subsequent thermal treatment. The Cu-doped SnO_x particles are uniformly distributed in the CNFs and maintain the original morphology after long-term cycling. In a controlled experiment, SnO_x-20%Cu/CNFs with an atomic ratio of Cu : Sn = 0.2 shows the highest electrochemical performance with a high reversible capacity of 743 mA h g⁻¹ at a current density of 200 mA g⁻¹ and an excellent rate capacity of 347 mA h g⁻¹ at 5 A g⁻¹. Moreover, the composite electrode exhibits an outstanding long-term cycling performance at 2 A g⁻¹ even after 1000 cycles. The superior reversible lithium-ion storage capability is attributed to the uniform dispersion of the Cu₂O and ultrafine SnO_x particles in CNFs as well as the Cu-addition effects such as promoting electron transport and Li⁺ diffusion, preventing Sn from aggregation during cycling, and improving the reversibility of Sn back to SnO_x in the recharge process.