Low-cost 3D porous sea-hedgehog-like NiCo₂O₄/C as anode for Li-ion battery

Carbon is effective additive to improve cyclic performances of transition metal oxides for lithium ion battery, while common graphene or carbon nanotube is expensive. In this study, waste of rice husk is used to prepare low cost carbon. A composite of NiCo₂O₄/carbon is synthesized via hydrothermal method plus calcination. At hydrothermal time of 6 h, the material displays 3-D sea hedgehog-like structure with radial corn cob-shaped nanorod. The NiCo₂O₄/carbon presents better rate performances, coulombic efficiency and cyclic stability than pristine NiCo₂O₄, showing stable capacity of 1018 mAhg^-1 (52.6% higher than NiCo₂O₄) after 100 cycles at 0.1 Ag^-1. For long-term cycling during 500 cycles at 0.5 Ag^-1, the composite anode exhibits a reversible capacity of ∼880 mAhg^-1, with high retention of 92.2%. The capacity is still retained ∼715 mAhg^-1 even after 1000 cycles at 1 Ag^-1.