Nitrogen-doped graphene supported NiFe2O4 nanoparticles as high-performance anode material for lithium-ion batteries

Nitrogen-doped graphene supported NiFe2O4 nanoparticles (NiFe2O4-NG) composite was successfully synthesized by a simple hydrothermal method. In the NiFe2O4-NG nanocomposite, the surface of nitrogen-doped graphene sheets was loaded by a large number of uniform NiFe2O4 nanoparticles with the mean size of 8 nm. Meanwhile, the nitrogen-doped graphene sheets were exfoliated. As anode materials for lithium ion batteries, the initial discharge and charging capacities of NiFe2O4-NG electrode are 1888 and 1242 mAh g−1, respectively, and the coulomb efficiency is 65.8%. Furthermore, the capacity of NiFe2O4-NG is 1100 mAh g−1 after 50 cycles. Compared with pure NiFe2O4, the superior electrochemical performance of the NiFe2O4-NG nanocomposite is mainly attributed to the unique architecture of smaller NiFe2O4 nanoparticles loaded on the high conductivity of nitrogen-doped graphene sheets, as well as the synergy effect between the nitrogen-doped graphene and nanoparticles. The high specific surface area of NiFe2O4-NG can increase the interface area between electrode and electrolyte, ensuring the full contact between electrode surface and electrolyte. The strong interaction between nitrogen-doped graphene and nanoparticle is beneficial to effectively suppress the volume expansion and the rapid ion/electron transport during the charge–discharge process. Profiting from structure and composition characteristics, the above-mentioned NiFe2O4-NG electrode delivers an excellent capacity, cycle performance and rate capability.