Preparation Of Antimony Sulfide Anode Based On Conversion Reaction And Its Sodium-Storage Properties

Sb₂S₃ has been investigated as a typical anode for sodium ion batteries based on conversion reaction, with theoretical capacity of 946 mAh/g, stable charge-discharge platforms, favorable reversible processes. Besides, Sb₂S₃ possesses the merits of thermstability, easy preparation and the competive price. It is promising to be used as anode materials for high capacity sodium-ion batteries. However, Sb₂S₃ is great inhibited by large volume changes upon sodiation and desodiation. DFT computational studies indicated that the elastic moduli of materials are decreased by 65%, which result in poor cycling of structural stability. In order to modify the electrochemical properties of Sb₂S₃, we adopt strategies as following: designed Sb₂S₃ nanosheets self-assembled flowerlike structutre, synthesized one-dimensional Sb₂S₃ nanowires templated graphene scrolls（Sb₂S₃GSs）, built supporting framework by substituted Sb with Cu.（1）Flower-like Sb₂S₃ has been prepared through a simple and facile polyol refluxing process. Nanosheets self-assembled micro-flowers structures not only mitigate volume expansion, but also provide effective diffusion pathways for electrons and sodium ions. When tested as an anode for sodium-ion batteries, the material delivers high reversible capacity of 835.3 mAh/g at 50 mA/g after 50 cycles, and maintains a capacity of 641.7 mAh/g at 200 mA/g after 100 cycles. Even up to 2000 mA/g, a capacity of 553.1 mAh/g can be obtained, indicating excellent cycle performance and superior rate capability.（2）One-dimensional Sb₂S₃ nanowires templated graphene scrolls（Sb₂S₃GSs） have been synthesized though two-step wet chemical processes. The Sb₂S₃ GSs could accommodate volume expansion by means of bending and wrapping within graphene sheets. Repeated volume change may lead to pulverizing of Sb₂S₃ nanowires after several times of cycling, but graphene scrolls limited the particles within it. Sb₂S₃ GSs have been applied as anode materials for lithium-ion and sodium-ion batteries（LIB, NIB）, it delivered high reversible capacity of 690 mAh/g and 680 mAh/g at current densities of 50 mA/g without any capacity fading over 50 cycles both in LIB and NIB. Further research on optimizing electrolyte manifested that 1 M NaClO4 in EC/DMC promoted the electrochemical performance of NIB. After 100 cycles charge and discharge at current density of 50 mA/g, no capacity fading was observed.（3）To obtain CuSbS₂ nanoparticle decorated graphene composite by means of solvothermal method. Here we applied it as the anode material for sodium-ion batteries for the first time. CuSbS₂ framework supporting lattice was established by partially replace Sb with Cu to produce CuSbS₂. Copper is electrochemical nonactive in Na cells, so it can relieve lattice distortion and improve mechanical property of the resultant material. Both graphene and coppor is good conductor of electricity which can promote electrical conductivity of composite. Their electrochemical properties were studied by constant current charge-discharge test, CuSbS₂ nanoparticle decorated graphene composite shows capacity retention of 85.8% after 200 cycles, indicating good cycle performance.