| One of the greatest challenges of modern society is to stabilize a consistent energy supply that will meet our growing energy demands. Battery technology is the crucial problem of the development of electric vehicles (EVs). Developing large capacity density, high power density, safe and reliable lithium-ion batteries (LIBs) is an urgent target of scientists. The key to improve the performance of lithium ion batteries is to develop a suitable electrode material. Considerable efforts have been devoted to the development of advanced electrode materials. Moreover, owing to the low cost and earth abundance of material, sodium-ion batteries (NIBs) has become a research highlight to be applied in large scale energy device. The thesis focuses on the research of iron sulfide (FeS) applying as cathode material for LIBs and NIBs.In Chapter 1, the author briefly introduces the working mechanism of LIBs and NIBs, mainly introduce some cathode and anode materials of LIBs and NIBs. At the end of Chapter 1, the research innovation and method are present.In Chapter 2, the author lists the reagent used in this article, and introduces some synthetic methods involved. In the third and fourth part of Chapter 2, the author presents the instruments of materials characterization and batteries test.In Chapter 3, the author introduces a method using Prussian blue as template to synthesis FeS composite with carbon, and adding nanotubes (CNTs) to structure conductive matrix, improving the capacity and rate capability of electrode materials. In order to further improve the cycle stability of the material, carbon interlayer which is produced by electrospinning method is set between the diaphragm and electrode slice. This method shows positive effects on the cycle performance of electrode materials, after 50 cycles, the battery still possess 325 mA h g"1 at a current of 0.1 C (1C=609 mA g-1), which is larger than the battery without carbon interlayer (200 mA h g-1).In Chapter 4, flexible and self supported carbon coated FeS on carbon cloth films (denoted as FeS@C/carbon cloth) is prepared by a facial hydrothermal method combined with a carbonization treatment. The FeS@C/carbon cloth could be directly used as electrodes for Li-ion batteries (LIBs) and sodium-ion batteries (NIBs). The synthetic effects of the structure, highly electron conductive of carbon cloth, porous structure for electrolyte access, and uniform carbon shell on FeS surface to accommodate the volume change lead to improved cyclability and rate capability. For lithium storage, the FeS@C/carbon cloth electrode delivers a high discharge capacity of 420 mAh g-1 even after 100 cycles at a current density of 0.15C and370mAh g-lat a high current density of 7.5C(1C=6O9 mA g-1. When used for sodium storage, it keeps a reversible capacity of 365mAh g"1 after 100 cycles at 0.15C.Similar process can be utilized for the formation of various cathode and anode composites on carbon cloth for flexible energy storage devices.In Chatper 5, the author introduces the other research at the graduate level. By compared the electrochemical performance of three composites (GeO2 dispersing in mesoporous carbon microspheres, carbon nanotube, and reduced graphene oxide), the GeO2 embedded in 0D mesoporous carbon microspheres (denoted as GeO2@MCS) shows a rather better electrochemical performance including cyclability (852 mA h g-1 at a rate of 0.5 A g-1 after 100 cycles) and rate capability (269 mA h g-1 at 10 A g-1 after 50 cycles).In Chapter 6, the author gives a summary of the series research, including the innovation and defects. The further R&D can be carried out on the basis of this article is pointed out at the end of Chapter 6. |
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