High performance of mesoporous γ-Fe2O3 nanoparticle/Ketjen Black composite as anode material for lithium ion batteries

• A mesoporous γ-Fe2O3/KB composite was synthesized via solvothermal method.
• KB was used as a carbon template to improve electrochemical performance of γ-Fe2O3.
• 3D network structure can relieve volume change and improve the ionic transport.
• The composite exhibited an ultrahigh capacity and high rate performance.

A type of γ-Fe2O3 nanoparticle/Ketjen Black (KB) composite material is synthesized by a solvothermal method combined with precursor thermal transformation. The structure and morphology are characterized by XRD, raman spectra, TG, nitrogen sorption, SEM, TEM and EDS. The results show that the composite has a uniform nanoporous network and well-dispersed γ-Fe2O3 particles with a size of ca. 5 nm are embedded in the mesopores of KB. The γ-Fe2O3/KB exhibits superior eletrochemical performances to the bare γ-Fe2O3, especially at high current rate. The discharge capacity of the composite is 1100 mAh·g−1 at the first cycle and remains 988.8 mAh·g−1 after 100 cycles at 0.2 C. Moreover, it also maintains a high discharge capacity of 697.8 mAh·g−1 at 2 C and 410.1 mAh·g−1 at 5 C after 100 cycles, respectively. Such improved electrochemical performances could be attributed to the superior conductivity and favorable structure of KB, which contributes to the improvement in electronic conductivity and structure stability of γ-Fe2O3 during the lithium ion insertion/desertion process.