| High-energy-density and high-specific-capacity rechargeable lithium-sulfur batteries have attracted increasing attention for the next-generation rechargeable batteries.However, in its research and application, there are still a number of obstacles to overcome, such as the highly insulating of sulfur, the solubility of lithium polysulfides(Li2Sx, x>4) and large volume expansion of sulfur cathode.Spherical carbon aerogel, carbon aerogel with vanadium and V2O3 modified carbon microsphere as cathode matrix were prepared by using catalyst of organic acids, in-situ method and wet impregnation method, respectively. The surface morphology and structure of composites, the adsorption abilities of samples on lithium polysulfides and the electrochemical performance of these composites based sulfur cathodes were investigated systematically.The results show the surface areas of CAs were controlled by the structure and length of catalyst chains. The samples by organic acid catalyzing present hierarchical porous structure. And this feature is beneficial to store sulfur, restrain soluble polysulfides and disperse sulfur. The CA with a higher surface area presents good electrochemical performance. Moreover, the spherical CA with VN displays high electrochemical performance due to its hierarchical pore and uniform dispersion of vanadium nitride. And it also has a catalytic effect on the electrode reaction. It presents excellent cycling performance and rate capability. S/VCA-3 exhibits a higher initial discharge capacity of 1279 mAh g"1 at 0.2 C, and retains 1001 mAh g-1 after 100 cycles.Even at a higher rate of 1 C, the capacity still delivers 802 mAh g-1 after 100 cycles.Furthermore, an ultrafine V2O3 modified carbon microsphere traps polysulfides and mitigates loss of active materials by chemical adsorption. S/VCM shows a high initial discharge capacity of 1177 mAh g"1 at 0.5 C and a high cycling performance with 921 mAh g-1 after 100 cycles. |
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