Preparation Of Three-dimensional Nanoporous Tin-based Alloy By Cyanide Liquid Phase Reduction Method And Its Lithium Storage Performance

Owing to their high specific capacities and safety, tin-based alloys have been considered to be one of the most promising anodic candidates to replace commercial carbon anodes in Li-ion batteries. However, state-of-the-art anodic performances of tin-based alloys are not satisfactory because of their poor cycling stability and rate capability, which hinder their practical application in Li-ion power batteries for transportation and stationary energy storage. To overcome these difficulties, in this thesis we propose to fabricate three-dimensional (3D) nanoporous tin-based alloys as anodes,using tin-based cyanogel systems as precursors. The 3D nanoporous structure is beneficial for enhancing the cycling stability and improving the rate capability of alloy systems.Furthermore, their lithium storage capabilities will be modified and optimized through the compositional design and carbon coating approaches, with the purpose of obtaining advanced tin-based alloy anodes for Li-ion power batteries, as well as revealing the physicochemical mechanism.(1) By using Sn(IV)-Ni(II) cyanogel as a precursor, 3D nanoporous Sn-Ni alloy has been fabricated via a facile wet-chemical reduction process. Compared with Sn-Ni alloy particle, 3D nanoporous Sn-Ni alloy manifests enhanced lithium storage performance. For example, the 3D nanoporous Sn-Ni alloy is able to deliver a high reversible capacity of 219.4 mA h g-1 in the 100th cycle at a current density of 100 mA g-1.which is much higher than that of Sn-Ni alloy particle (10.8 mA h g-1).(2) By using Sn(IV)-In(III)-Ni(II)-Co(III) cyanogel as a precursor, 3D nanoporous Sn-In-Ni alloy has been prepared via a facile wet-chemical reduction process. The as-prepared Sn-In-Ni ternary alloy network manifests much higher reversible capacities,marekly improved cycling stability and rate capability in comparison with Sn-Ni binary alloy and metallic In networks. For example, the 3D nanoporous Sn-In-Ni alloy is able to deliver a high reversible capacity of 617.7 mAh g-1 in the 200th cycle at a current density of 100 mA g-1, which is much higher than those of separate Sn-Ni (160.0 mA h g-1) and In(25.8 mAh g-1) and the theoretical capacity of commercial graphite (372 mAh g-1).(3) By using CB@Sn(IV)-Ni(II) cyanogel as a precursor, 3D nanoporous CB@Sn-Ni alloy has been prepared via a facile wet-chemical reduction process. Compared with bare Sn-Ni alloy, the 3D nanoporous CB@Sn—Ni alloy reveals significantly improved Li-storage performance. For example, even at a high current density of 1 A g-1, the average capacity of 3D nanoporous CB@Sn-Ni alloy is 260.8 mA h g-1, which is much higher than that of bare Sn-Ni alloy (37.7 mA h g-1).