New synthesis of a foamlike Fe₃O₄/C composite via a self-expanding process and its electrochemical performance as anode material for lithium-ion batteries

A novel foamlike Fe₃O₄/C composite is prepared via a sol-gel type method with gelatin as the carbon source and ferric nitrate as the iron source, following a postannealing treatment. Its lithium storage properties as anode material for a lithium-ion battery are thoroughly investigated in this work. With the interaction between ferric nitrate and gelatin, the foamlike architecture is attained through a unique self-expanding process. The Fe₃O₄/C composite possesses abundant porous structure along with highly dispersed Fe₃O₄ nanocrystal embedment in the carbon matrix. In the constructed architecture, the 3D porous network property ensures electrolyte accessibility; meanwhile, nanosized Fe₃O₄ promotes lithiation/delithiation, owing to numerous active sites, large electrolyte contact area, and a short lithium ion diffusion path. As a result, this Fe₃O₄/C composite electrode demonstrates an excellent cycling stability with a reversible capacity of 1008 mA h g^-1 over 400 cycles at 0.2C (1C = 1000 mA g^-1), as well as a superior rate performance with reversible capacity of 660 and 580 mA h g^-1 at 3C and 5C, respectively.