The spinel MnFe2O4 grown in biomass-derived porous carbons materials for high-performance cathode materials of aqueous zinc-ion batteries

Abstract

Here a novel composite material that is described by the MnFe2O4 with spinel structure in-situ grown on the biomass-derived amorphous porous carbon (PC@MFO) is proposed as a cathode material for aqueous zinc-ion batteries (AZIBs). This electrode has an excellent initial discharge capacity of 168 mA h g−1 at 0.3 A g−1 and superior cycle stability with capacity retention rate of 92% over 900 cycles even at a high rate of 1 A g−1. The excellent charge/discharge performance of PC@MFO electrode is attributed to some beneficial synergistic effects including increasing good electrode conductivity and high ion transmission speed and more reactive points and avoiding the rapid collapse of the structure of the MnFe2O4 electrode produced by the introduction of mesoporous carbon, which promotes and stabilizes charge/discharge reaction of multivalent redox (Mn2+/Mn4+, Fe2+/Fe3+). The rapid electrochemical kinetic behavior of the PC@MFO electrode is also analyzed by cyclic voltammetry, where the kinetic process of electrochemical reaction involving the diffusion control faraday process and capacitance control behavior is revealed and the capacitance contribution rate of about 88.19% is attained. Moreover, the galvanostatic intermittent titration technique (GITT) also explains that this PC@MFO electrode has a high Zn2+ ion diffusion capacity and the diffusion coefficient can reach 10−14~10−10 cm2 s−1. In addition, the reaction mechanism and structural evolution of this electrode is also studied by ex-situ X-ray photoelectron spectroscopy (XPS) and X-ray diffraction test (XRD) from different cycle stages. XPS and XRD reveal the strong deintercalation ability of Zn2+ ions in the highly stable MFO which grows in biomass-derived porous carbon. The present result implies that such a PC@MFO composite material could be a promising cathode material for AZIBs.