Revealing the unique process of alloying reaction in Ni-Co-Sb/C nanosphere anode for high-performance lithium storage

The strategy of "template sacrifice method" was proposed to synthesize well-defined NiSb/CoSb nanoparticles embedded in carbon nanosphere (Ni-Co-Sb/C, ~560 nm) by calcination treatment of the Ni-Co-MOF (metal-organic framework) precursor. Due to the structural controllability of MOF precursor and Ni/Co bimetallic synergy, the fabricated Ni-Co-Sb/C demonstrates a high surface area (88 m² g^-1) and superior ion conductivity, thus an excellent electrochemical performance as has been achieved as lithium ion battery (LIB) anode. A reversible discharge specific capacity as high as 495.1 mAh g^-1 has been stably delivered after 1000 cycles at a high current density of 1.0 A g^-1. In addition, the charge transfer impedance of Ni-Co-Sb/C electrode is as low as 67.6 Ω in the 30th cycle at 0.1 A g^-1 and the pseudocapacitive contribution is as high as 73.8% at 0.5 mV s^-1. The alloying mechanism of Ni-Co-Sb/C has been verified by in-situ X-ray diffraction (XRD), which enables a high lithium storage capacity. Moreover, the full-cell assembled with LiCoO₂ as cathode exhibits a steady discharge specific capacity of 354.0 mAh g^-1 at 0.1 A g^-1 even after 100 cycles. Our work provides an effective method for the application and high-capacity Sb-based material in energy storage fields, and this material is expected as a promising candidate for a novel anode material in LIBs.