Synthesis And Electrochemical Properties Of Sb-based And Bi-based Nanostructures Electrode Materials

This dissertation aims to improve the electrochemical performance of antimony?Sb?and bismuth?Bi?based anode materials in the application of advanced energy storage devices,including lithium ion batteries?LIBs?and sodium ion batteries?SIBs?.Herein we systematically investigated the novel design and controllable synthesis of Sb and Bi-based nanomaterials,employed advanced characterizations,and disclosed their energy storage mechanisms.The main significant achievements are briefly summarized as follows:?1?In order to address the fast capacity decay caused by severe volulme expansion and low conductivity of Sb anode,a novel composite with Sb nanoparticles anchored in three-dimensional carbon network?SbNPs@3D-C?was successfully synthesized via a NaCl template-assisted self-assembly strategy,followed by freeze-drying and one-step in-situ carbonization.The three-dimensional interconnected macroporous carbon framework can not only stabilize the architecture and buffer the volume expansion for Sb nanoparticles,but also provide high electrical conductivity for the whole electrode.Consequently,as a sodium-ion battery anode,the SbNPs@3D-C delivers a high reversible capacity(456 mAh g^-1 at 100 mA g^-1),stable cycling performance(85.5%capacity retention after 500 cycles at 2000 mA g^-1)as well as superior rate capability.When compared with commercial Sb particles,the SbNPs@3D-C exhibits dramatically enhanced electrochemical performance.Besides,the employment of NaCl template is facile and environmentally friendly,which would shed some light on the synthesis of low-cost and high-performance electrode materials.?2?We designed and fabricated a novel peapod-like N-doped hollow carbon tube encapsulated Sb nanorod composite?Sb@N-C?and the thermal-reduction process was monitored by in-situ high-temperature X-ray diffraction?HT-XRD?characterization.Due to its advanced structural merits,such as sufficient N-doping,one-dimensional conductive carbon coating,and substantial inner void space,the Sb@N-C demonstrated superior lithium/sodium storage performances.For lithium storage,the Sb@N-C exhibited a high reversible capacity(650.8 mAh g^-1 at 0.2 A g^-1),excellent long-term cycling stability(a capacity decay of only 0.022%per cycle for 3000 cycles at 2 A g^-1),and ultra-high rate capability(343.3 mAh g^-1 at 20 A g^-1).For sodium storage,the Sb@N-C nanocomposite displayed the best long-term cycle performance among the reported Sb-based anode materials(a capacity of 345.6 mAh g^-1 after 3000cycles at 2 A g^-1).The results demonstrate that the Sb@N-C nanocomposite is a promising anode material for high-performance LIBs and SIBs.?3?Metal chalcogenides have emerged as promising anode materials for LIBs and SIBs.Herein,a free-standing membrane based on ultralong Sb₂Se₃ nanowires has been successfully fabricated via a hydrothermal synthesis combined with a subsequent vacuum filtration treatment.The as-achieved freestanding membrane constructed by pure Sb₂Se₃ nanowires exhibits good flexibility and integrity.When applied as an anode for LIBs or SIBs,the Sb2Se3 membrane demonstrates good electrochemical performance.Futhuermore,a fast?0.5 h?,green microwave-assisted synthesis of single crystalline Sb₂Se₃ nanowires was developed.For the first time we demonstrated a facile solvent-mediated process,whereby intriguing nanostructures including Sb2Se3nanowires and Se microrods can be achieved by merely varying the volume ratio of solvent.When evaluated as an anode for LIBs,single crystalline Sb₂Se₃ nanowires can deliver a high reversible capacity of 650.2 mAh g^-1 at 100 mA g^-1 and a capacity retention of 63.8%after long-term 1000 cycles at 1000 mA g^-1,as well as superior rate capability.?4?Constructing novel heterostructures has great potential in tuning the physical/chemical properties of functional materials energy conversion and storage.Herein heterostructured Bi₂S₃-Bi₂O₃ nanosheets?BS-BO?have been prepared through an easy water-bath approach.The formation of such unique BS-BO heterostructures was achieved through a controllable thioacetamide-directed surfactant-assisted reaction process.When employed as the SIBs anode material,the resultant BS-BO displays a reversible capacity of?630 mAh g^-1 at 100 mA g^-1.In addition,the BS-BO demonstrates improved rate capability and enhanced cycle stability compared to its Bi₂O₃ sheets and Bi₂S₃ sheets counterparts.The improved electrochemical performance can be ascribed to the built-in electric field in the BS-BO heterostructure,which effectively facilitates the charge transport.This work can shed light on the construction of novel heterostructures for high-performance SIBs and other energy related devices.