| Energy crisis is the main serious problem which has received considerable attention due to the increasing interest of depletion of fossil fuels. At present, electric vehicles and high energy/power density of storage devices use the electrochemical energy storage based on demand of industry. Among the secondary electrochemical energy storage device, rechargeable lithium-ion batteries have become the most promising energy storage device due to the high energy density, long cycle life and low cost. To improve the electrochemical performance of lithium-ion batteries, develop the novel electrode materials is the one of the effective method. So lots of research groups study on how to develop novel electrode materials with low-cost, good electrochemical performance and environment-friendly. Supercapacitor is the other high performance of energy storage device, depanding on the charge adsorption/desorption on the surface of electrode materials when charging/discharging. Supercapacitor has a wide range of application in the novel energy storage, electric vehicles, power weapons and other fields due to its high rate, high power density, long cycle life and wide working temperature range. Research of nanoscale materials has promoted flourish of advanced energy storage technology. However, common problems involved with nanomaterials such as bad structural continuity, conglomeration and structural instability have restricted their application in supercapacitors. In this work, we introduce four strategies based on desigh of electrode materials with high surface area aiming to improve the performace of lithium-ion batteries ans supercapacitor. We have conducted the design, synthesis and electrochemical test of the electrode materials containing:the composite of porous metal materials with multi-compound anode, two dimensional structural composite and mesoporous metal sulfide anode. We demonstrate the above composite materials have wide prospect for application in the supercapacitors as well as lithium-ion batteries.In the second charpter, we present a hybrid structure involving a small quantity of Co element uniformly deposited on porous SnO2 spheres as stable and high capacity anode materials for lithium-ion batteries. Specifically, Co element deposited on SnO2 nanomaterials exhibited an exceptional reversible capacity of 810 mA h g-1 after 50 cycles which is higher than the pure SnO2 electrode. Based on the experiments results, a possible mechanism for the change of this structure during lithium ion insertion/extraction was proposed. The minute quantity of Co element uniformly deposited on SnO2 spherical structure could prevent Sn aggregation during charging/discharging and high porosity of the spherical structure allowed the volume expansion during lithium ion alloying/dealloying. The SnO2 deposited with small quantities of Co element as electrode facilitated improved performance of lithium ion batteries with higher energy densities.In the third charpter, a hybrid structure involving efficient plentiful ultrasmall SnS2 nanocrystals decorated on flexible reduced graphene oxide (rGO) has been successfully realized via a refluxing method. The ultrasmall SnS2 nanocrystals can compactly and orderly cover the rGO nanosheets, increasing the loading number of SnS2 per unit area of the rGO substrates. The ultrasmall SnS2 nanocrystals@rGO nanocomposites were investigated as electrode materials for lithium-ion batteries. In this hybrid structure, rGO was not only used as a solid support to uniformly distribute the SnS2 nanocrystals, but also as a carrier to accelerate electron transport. In addition, the uniform size and homogeneous SnS2 nanocrystals on the rGO nanosheets reduced electrode polarization, resulting in excellent electrochemical performance for lithium-ion batteries. The cost-effective synthesis of SnS2 nanocrystals@rGO and excellent electrochemical performance indicates the great potential for this type of nanocomposites asan a ctive electrode for lithium-ion batteries.In the fourth charpter, high-selectivity, uniform three-dimensional flower-like CoMoS3.13 nanostructure consisting of few-layer nanosheets were synthesized for the first time by a facile, one-step hydrothermal route with ethanol as the structure-director. The samples were systematically investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The SEM clearly showed that the products were 3D nanostructures consisted of well-defined nanosheets. The average diameter of the bottom flower was 50±5 nm. As a proof-of-concept demonstration of the functional properties of the unique structure, the 3D CoMoS3.13 nanostructure was investigated as an electrode material for electrochemical energy storage. Electrochemical performances demonstrated that the obtained CoMoS3.13 showed three-dimensional architecture and excellent cycling stability and high-rate capability for supercapacitors and lithium-ion batteries.In the final charpter, a novel hierarchical CoNi2S4 arrays consisting of uniformly coverage of thin sheets and numerous nanobranches on Ni foam has been successfully prepared via a simple one-step hydrothermal route without any surfactant and template. The CoNi2S4 arrays were investigated as electrode material for supercapacitors. The ordered CoNi2S4 arrays self-grown on Ni foam provided an excellent conducting connection with electrode substrates. Meanwhile, the thin sheets on top of the arrays are interconnected, forming a highly specific surface area. The unique architecture has constructed many independent nanospaces to participate in electrochemical reaction. Detailed electrochemical characterization showed the novel structure has an excellent electrochemical capacitance, high rate performance and high areal capacitance. The cost-effective synthesis of CoNi2S4 arrays and remarkable electrochemical performance provided great potential for this type of hybrid hierarchical nanostructures in supercapacitors. |
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