Synchronous Synthesis Of Carbonous Tin-Based And Antimony-based Composites And Their Electrochemical Performances

This paper developed a C2H2synchronous reduction and carbon deposition process to prepare tin-based and antimony-based composites. The reduction of the Sn4+or Sb3+and the decomposition reaction of C2H2are conducted at the same time during the sintering process. It is controllable to synthesis of carbonous tin-based and antimony-based composites by regulating the composition, morphology, and structure of precursors. Meanwhile, the carbon content in the composite can be controlled by regulating the calcining temperature and time. The C2H2adopted in the preparing process is not only as the carbon precursor, but also as the reductive agent which promotes the reduction of Sn4+or Sb3+. The main contents are summarized as follows:1. Uniformly dispersed carbon coated Sn-MnO nanocomposite (Sn-MnO@C) has been fabricated by thermal annealing of MnSn(OH)6nanoparticles precursor in acetylene/argon gas. Benefiting from this unique method, the synchronously formed Sn@C and MnO@C nanocrystals both with size about12nm were uniformly dispersed in the amorphous carbon matrix. Meanwhile, a porous structure appeared which could be attributed to the dehydration of MnSn(OH)6in the calcination process. As the anode for lithium-ion batteries, the Sn-MnO@C nanocomposite demonstrates a reversible capacity of684mA h g-1after280cycles at a current of100mA g-1. The fine electrochemical performance mainly attributes to uniformly dispersed nanoparticles, porous structure as well as amorphous carbon matrix coating.2. SnSb-C and Sn-C composites have been fabricated by thermal annealing of the SnO2-Sb2O3and SnO2nanocomposite precursors under C2H2-pyrolysis reducing atmosphere, respectively. Both of the as-formed SnSb intermetallic compounds and Sn particles are uniformly dispersed in the synchronously formed continuous amorphous carbon matrix. As the anode for lithium-ion batteries, the SnSb-C composite shows a high reversible capacity of672.2mA h g-1after120cycles at a current density of100mA g-1, which is much better than that of the corresponding Sn-C composite (with similar carbon content as SnSb-C composite;432.1mA h g-1after120cycles at100mA g-1). The better reversible capacity and cyclic performance of SnSb-C composite can be attributed to the synergistic effect and strong affinity between electrochemical Sn and Sb phases as well as the synchronously formed continuous amorphous carbon matrix.3. Rod-like Sb-C composite has been synthesized by thermal annealing of the porous Sb2O3microrod precursors under C2H2-pyrolysis reducing atmosphere. The as-formed Sb particles are coated by the synchronously formed continuous amorphous carbon matrix. The rod-like Sb-C composite anode exhibits a reversible capacity of478.8mA h g-1at100mA g-1after100cycles for Li-ion batteries and exhibits a reversible capacity of430.9mA h g-1at50mA g-1after100cycles for Na-ion batteries. The fine electrochemical performance mainly attributes to special porous microrod structure as well as the amorphous carbon matrix coating.4. Microflower-like ZnSb@C composite has been synthesized by thermal annealing of the microflower-like Zn(OH)2-Sb2O3precursors under C2H2-pyrolysis reducing atmosphere. While the ZnSb-C composite has been synthesized via the similar approach except the mixed Sb2O3octahedrons and ZnO nanorods precursors. The Zn and Sb phase are more uniform distribution in the flower-like Zn(OH)2-Sh2O3precursors than that of mixed precursors, which is beneficial to promote the generation of microflower-like ZnSb@C composite. As the anode for lithium-ion batteries, the microflower-like ZnSb@C composite shows a high reversible capacity of513.1mA h g-1after100cycles at a current density of100mA g-1, which is much better than that of the corresponding ZnSb-C composite (331.6mA h g-1after100cycles at100mA g-1). The better reversible capacity and cyclic performance of microflower-like ZnSb@C composite can be attributed to special microflower-like structure as well as the amorphous carbon matrix coating.