Hierarchical bead chain ZnFe2O4-PEDOT composites with enhanced Li-ion storage properties as anode materials for lithium-ion batteries

Abstract

In this study, we synthesized hierarchical bead chain ZnFe2O4-PEDOT composites with network of macroporous channels. For the first time, a ZnFe2(C2O4)3 precursor was prepared by co-precipitation using steel waste pickling liquor as a raw material, which was then sintered in air at 800 °C to yield monolithic ZnFe2O4. PEDOT was coated on the surface of ZnFe2O4 via in-situ polymerization of 3,4-ethylenedioxythiophene (EDOT). Electrochemical measurements showed that the 15 wt% PEDOT coated ZnFe2O4 composites (ZFPE-15) delivered a discharge capacity of 1510.5 mAh g−1 at 100 mA g−1 after 200 cycles, which was much larger than that of pure ZnFe2O4 (1055.9 mAh g−1), 10 wt% PEDOT coated ZnFe2O4 composites (ZFPE-10, 1264.2 mAh g−1), and 20 wt% coated ZnFe2O4 composites (ZFPE-20, 900.1 mAh g−1). Additionally, the ZFPE-15 composite exhibited a reversible capacity of 1004.7 mAh g−1, even at a large current density of 1 A g−1 after 200 cycles. These more desirable electrochemical properties can be attributed to the interconnected macroporous channels in the hierarchical bead chain skeleton, which can buffer volume expansion during circulation and inhibit particle agglomeration. Furthermore, the PEDOT nanoparticle coating produces a composite with greater mechanical strength and higher electrical conductivity, which provides higher electron transfer during the charge/discharge processes.