Co/Ni-MOF-74-derived CoNi2S4 nanoparticles embedded in porous carbon as a high performance anode material for sodium ion batteries

In this study, Co/Ni-MOF-74-derived CoNi(2)S(4)nanoparticles embedded in porous carbon (CoNi2S4@C) were successfully prepared using Co/Ni-MOF-74 as precursor. According to the SEM and TEM images, the CoNi(2)S(4)nanoparticles with a diameter of about 8 nm were uniformly distributed in the composite. Compared to the pure CoNi2S4, CoNi2S4@C exhibits excellent electrochemical performance as an anode material for sodium ion batteries (SIBs). After 50 cycles (at 100 mA g(-1)), the specific capacity of CoNi2S4@C could be maintained at 438 mA h g(-1). After the CoNi2S4@C electrode was charged/discharged at different current densities of 50, 100, 200, 500, 800, 1000, and 2000 mA g(-1), the specific capacity returned to the original level when the current density was restored to 50 mA g(-1). This is due to the fact that the composite material can reduce the effect of volume expansion.