Preparation And Electrochemical Properties Of Novel Antimony-based Anode Materials For Li-ion And Na-ion Batteries

In recent years, the requirement of the energy storage systems with high voltage operation, high reversible specific capacity and more safety have required us to research new battery materials as the development rapidly of the 3C electric devices and peoples' rising stranded of living. The metal antimony?Sb?,located in group V and the five period in The Elements and The Periodic Table, display the same chemical property as the metal Sn and Si and have been reported as another class of well materials for LIBs and SIBs anodes. The first, our China is the largest Sb producing nation and the resource of the Sb is abundant and low cost. The second, the theory capacity of Sb is up to 660 mA h g^-1, with a safe potential plateau range of 0.6-0.8 V, which could avoid the dendritic crystal occurred and enhance the safety performance; the Sb anode could also provide a flat potential plateau and stable output voltage during the Li+/Na+ insertion/extraction process. However, the biggest disadvantage of the Sb material is the substantial volume change ?175% vs. Li, 293%vs. Na? during the Li+/Na+ insertion/extraction processes. In this thesis, a in-suit synthesis method was utilized to synthesized the Sb coated by carbon composites and Sb-based alloy with different morphology, which could remitted effectively the drastic volume change in the reaction process and display excellent cycle stability and rate capability. As follows:First, in this paper, the Ni-MOFs which synthesized by hydrothermal reaction as the precursor were restored to Ni???C composites by reductive roasting, and then NiSb???CHSs alloy was synthesized by in-suit synthesis method with Ni???C and Sb3+.The final product NiSb???CHSs alloy inherited the metal-organic framework advantages of high surface area(116.9 m2 g^-1),stability structure and higher porosity,the diameter of the hollow microspheres is about 1 ?m and dispersed uniformly, the NiSb nanoparticles were embedded in hollow microspheres and the formed carbon coated on the surface of the NiSb alloy which as the protective layer. As the battery anode material, the NiSb???CHSs alleviated the volume change in one hand, increase the contact area with the Li+/Na+ and improve the electric conductivity, exhibited remarkable electrochemical performance. As the Li-ion battery anode, the discharge capacity still revealed 497.3 mA h g^-1 after 100 cycles at a current density of 100 mA g^-1. And as the Na-ion battery anode and the full cells assembled with the LiMn2O4 cathode all present excellent electrochemical performance.Second, we chose the SnO₂ nanoparticles as the precursor and synthesized Sb@C hollow sphere nanoparticles by carbon coated use the hydrothermal method,high-temperture reaction and nanoconfined replacement. The SEM and TEM analysis results shown the Sb@C nanoparticles uniformLy distributed and a diameter of about 250 nm, inside of the sphere was hollow duo to the Kirkendall Effect and the specific surface area was up to 204.9 m2 g^-1. The Sb@C core-shell hollow sphere could provide extreme pathway for the volume change and prevent the structure from collapsing, improved the higher contact area of Sb and Li+/Na+, preserved stable SEI film and presented higher specific capacity. As Li-ion batteries anode, a reversible capacity still revealed 525 mA h g^-1 after 100 cycles at a current density of 50 mA g^-1,and the products delivered a stable capacity of 398 mA h g'1 after 300 cycles at a high current density of 1000 mA g^-1. As Na-ion batteries anode, the Sb@C hollow sphere also delivered a capacity of about 400 mA h g^-1 after 100 cycles at a current density of 50 mAg^-1.