| Energy and environment are two major issues currently facing the world. With the rapid development of gold industry, the easily treated golden ore resources are facing crisis. It is an urgent task to develop and utilize the numerous refractory gold ore resources. Biological oxidation technology for extracting gold is an effective one. However, in the process of biological oxidation technology, a large amount of acidic waste liquid containing valuable elements such as arsenic, iron and sulfur will be produced. So it is significant to explore a comprehensive treatment technology of biological oxidation, and to raise the level of utilizing the valuable elements in waste liquid.Rechargeable lithium ion batteries exhibiting high energy and high power density have rapidly conquered the consumer market of advanced portable electronics in recent years and are now considered as the next generation of power sources for future electric vehicles (EVs), hybrid EVs, and plug-in hybrid EVs. To meet the dramatically increased demand for the emerging large-scale applications of these EV, HEV and PHEV, electrode materials for LIBs with high safety, high power density and long cycle life are urgently required. Among the known cathode materials, olivine lithium iron phosphate (LiFePO4, LFP) is considered as an appealing candidate. LiFePO4 possesses advantages of potentially low cost, rich resources, and environmental friendliness. It also has a high lithium intercalation voltage of 3.4V compared with lithium metal and a high theoretical capacity of 170mAh·g-1. Although it displays plenty of attractive characters, the low electronic/ionic conductivity becomes a major drawback which is unfavorable to high rate capability. In order to further improve the power performance of LiFePO4, much effort has been made to improve the electrochemical properties of LiFePO4 by decreasing the particle size and coating LiFePO4 particles with conductive carbon.In order to realize the high value utilization of liquid iron, this thesis used FePO·xH2O which prepared by the liquid iron of Acidic metallurgical waste as raw materials, studied the preparation of lithium iron phosphate lithium-ion battery anode materials research, the main contents were as follows:(1) we synthesize LiFePO4/C composite materials by mechanical active--wwo-step solid method with FePO·xH2O and Li2CO3 as raw reaction materials. Synthesize LiFePO4/C composite by firstly annealing under 400℃ for 4h, followed by 650℃ for 14h. The LiFePO4/C composite has a first discharge capacity of 145.4mAh·g-1 under 0.1C, and with less than 3% loss rates with 10 cycles, which has a better electrochemical performance than the one made by traditional methods.(2) we make a research on the influence of structure, morphologies and performance by doping Mg2+、Co2+. We get the conclusion that appropriate amount elements doping can regulate the morphologies, refine the crystal size, enhance the Li ion diffusion rate and increase the capacity and rate performance. The material LiFeo.99Mgo.oiP04 has a first discharge capacity of 154.7mAh·g-1 under 0.1C, the material LiFe0.99Co0.01PO4 has a first discharge capacity of 154.0mAh·g-1 under 0.1C, which has a better performance than purity LiFePO4.(3) We synthesize xLiFePO4·yLi3V2(PO4)3 composite by the same method and research performance change with different x/y rate. And 5LiFePO·Li3V2(PO4)3 composite has a first discharge capacity of 153mAh·g-1 under 0.1C, and with less than 1% loss rates with 10 cycles, which has a better performance than purity LiFePO4. |
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