Designed Synthesis Of Metal Oxides And Oxysalts Nanomaterials And Their Applications In Lithium-ion Battery

Metal oxides and oxysalts materials have received considerable attention because of their widespread potential applications in areas of energy, photocatalysis, biomedical and so on. As anode materials, its disadvantages, such as significant structural changes and volume changes during discharge/charge process make it difficult to achieve high rate capabilities and a long cycling life. So, to overcome these problems, some efforts have been made to synthesize assembly, porous, or hollow metal oxides and oxysalts materials. In addition, as photocatalytic materials, their photocatalytic properties also have been studied. The main parts of the results are summarized as follows:1. In this work, nanocrystalline-assembled CuO bundle-like structures were successfully synthesized in large-quantity by a friendly, facile two-step process. The bundle-like CuO particles are produced by thermolysis of bundle-like Cu(OH)2precursors, which exhibit excellent high specific capacity, high stability, especially high rate performance for anode materials in lithium-ion batteries, superior to that of most reported CuO-based anodes. The assembled structure of CuO endue it with high rate capacities of666,609,499mA h g-1at a current rate of0.3C,1C and2C after50cycles, respectively. Even at high rate of6C, the bundle-like CuO can still deliver a capacity of361mA h g’. It is observed that the electrochemical perfonnance of the nanocrystalline-assembled bundle-like CuO is much better than that of CuO nanoparticles obtained by destroying the assembled bundle-like CuO through grinding. XRD analysis of the both electrodes after ending discharge/charge, proved that during discharge/charge process, the conversion reaction occurring in the assembled structures have better reversibility, leading to the high rate capacity and cycling performances. The better reversibility originates from the better contact area for CuO/electrolyte, enhancing lots of sites to access of Li+in the electrolyte Li+. In addition, the assembled bundle-like CuO architectures can also relieve the volume variations during Li+uptake-release process, which also contributes to the excellent electrochemical performance.2. Various CuO nanostructures have been well studied as anode materials for lithium ion batteries (LIBs); However, there are few reports on the synthesis of porous CuO nanostructures used for anode materials, especially one-dimensional (1D) porous CuO. In this work, novel1D highly porous CuO nanorods with tunable porous size were synthesized in large-quantities by a new, friendly, but very simple approach. We found that the pore size could be controlled by adjusting the sintering temperature in the calcination process. With the rising of calcination temperature, the pore size of CuO has been tuned in the range of～0.4nm to22nm. The porous CuO materials have been applied for anode materials in LIBs and the effects of porous size on the electrochemical properties were observed. The highly porous CuO nanorods with porous size in the range of～6nm to22nm yielded excellent high specific capacity, good cycling stability, and high rate performance, superior to that of most reported CuO nanocomposites. The CuO material delivers a high reversible capacity of654mA h g-1. It also exhibits excellent high rate capacity of410mA h g-1even at6C. These results suggest that the facile synthetic method of producing tunable highly porous CuO nanostructure can realize a long cycle life with high reversible capacity, which is suitable for next-generation high-performance LIBs.3. CdSnO3materials have been extensively studied as gas-sensing materials substances. However, there are few reports on the synthesis of porous CdSnO3nanostructures used for energy storage. Here, we report the preparation of highly porous CdSnO3nanoparticles with the size in the range of～7.8nm to28.7nm and the application of anode materials for rechargeable Li-ion batteries (LIBs). Electrochemical measurements showed that the highly porous CdSnO3nanoparticles prepared with citric acid deliver the higher reversible capacity (515mA h g-1,40cycle) after the second cycle and high rate capacity(506mA h g-1,150mA g-1) than these (370mA h g-1,40cycle;364mA h g-1,150mA g-1) of counterpart obtained without citric acid, which also exhibits the capacity enhancement compared with some previous reported in the literature.4. The synthesis of single-crystalline hollow particles with well-defined non-spherical shapes, especially hollow complex compounds, remains a significant challenge. In this paper, single-crystalline ZnSn(OH)6(ZHS) hollow cubes were first synthesized by a facile self-templating method at room temperature. On the basis of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy, it was found that hollow ZHS cubes were formed by a two-step process, in which solid cubes of ZHS were formed in first step due to the co-precipitation of Zn(II) and Sn(IV) under basic condition and then the solid cubes as the self-templates were converted to hollow ones through an alkali-assisted dissolution process. During the process, NaOH solution added in the second step is critical to the formation of ZHS hollow structures. The photocatalytic activity of ZHS hollow cubes for phenol degradation was tested, which showed much higher catalytic activity than that of the solid ZHS cubes. The photocatalytic activity of the ZHS hollow cubes is rather stable since it just decreased less after four trials.