Transition metal oxides are attractive as anode materials for lithium-ion batteries (LIBs) due to their high lithium intercalation capacity and generally high natural abundances and their use on the nanoscale is being actively pursued. However, there are still challenges associated with the use of these metal oxides, including the pulverization problem and limited electrical conductivity of many metal oxides. It has been shown that these problems may be alleviated by creating metal oxide-carbon composites, which improve upon the mechanical flexibility and the electrical conductivity of the material.
There are different approaches for creating the carbon composites such as carbon nanopainting and attaching the metal oxide nanoparticles to carbon substrates. The current work describes an alternative method of creating metal oxide-carbon nanocomposites, in which the metal oxide nanoparticles are created in situ and embedded in a porous carbon matrix, which is made through calcination of a polyacrylonitrile-based polymer. Fe3O4 is used as a model compound.
Characterization techniques such as X-Ray diffraction, transmission electron microscopy and Raman spectroscopy were used to investigate the physical and chemical properties of the composite. Cyclic voltammetry of the composite shows lithium intercalation at 1.2V and 0.8V, which may be attributed to the reduction of Fe3+ to Fe2+ and Fe2+ to Fe0, respectively. Very stable capacity is observed over >110 cycles at charging rate of 1C. Performance at other charging rates up to 5C is also shown and is seen to be stable. The contribution of factors including electrical conductivity, mechanical properties and porous nature of the carbon matrix in enhancing the electrochemical performance is investigated. The application of the method to other related materials such as MnO, Sn and Si is discussed.