Controlled synthesis of graphitic carbon-encapsulated α-Fe₂O₃ nanocomposite via low-temperature catalytic graphitization of biomass and its lithium storage property

A delicate structure of graphitic carbon-encapsulated α-Fe₂O₃ nanocomposite is in situ constructed via "Absorption-Catalytic graphitization-Oxidation" strategy, taking use of biomass matter of degreasing cotton as carbon precursor and solution reservoir. With the assistance of the catalytic graphitization effect of iron core, onion-like graphitic carbon (GC) shell is made directly from the biomass at low temperature (650 °C). The nanosized α-Fe₂O₃ particles would effectively mitigate volumetric strain and shorten Li⁺ transport path during charge/discharge process. The graphitic carbon shells may promote charge transfer and protect active particles from directly exposing to electrolyte to maintain interfacial stability. As a result, the as-prepared α-Fe₂O₃@GC composite displays an outstanding cycle performance with a reversible capacity of 1070 mA h g^-1 after 430 cycles at 0.2C, as well as a good rate capability of ∼ 950 mA h g^-1 after 100 cycles at 1C and ∼ 850 mA h g^-1 even up to 200 cycles at a 2C rate.