氮掺杂石墨烯海绵的可控合成及其在锂硫电池中的应用

Controllable Synthesis of N-Doped Reduced Graphene Oxide Sponge and Its Application in Li-S Batteries

摘要: 本研究采用水热法与热解法相结合的方法，以三聚氰胺海绵为模板对氧化石墨烯进行辅助组装，成功制备了形貌与尺寸可调的三维氮掺杂石墨烯海绵，并通过负载单质硫合成了氮掺杂石墨烯海绵@硫复合材料(N-RGOS@S)。采用XRD，TG，SEM，XPS对样品进行了表征。将N-RGOS@S作为锂硫电池正极材料进行电化学性能测试，测试结果表明，所制备的复合材料具有优异的循环稳定性，在0.1 C的电流密度下，经过100次循环后，放电比容量仍具有549.8 mAh∙g⁻¹。同时还具有优异的倍率性能，在电流密度为2 C时，可逆比容量可达到495.5 mAh∙g⁻¹。这种优异的电化学性能主要归功于三维石墨烯的网络结构和氮掺杂提高了电极材料的导电性，并且可以抑制多硫化物在充放电过程中的扩散，减少了穿梭效应的发生。

Abstract: In this study, N-doped reduced graphene oxide sponges (N-RGOS) with adjustable sizes and various morphologies were successfully fabricated by hydrothermal and pyrolysis methods, using melamine sponge as template for assisted assemble of GO. The N-RGOS@S composites were pre-pared by loading elemental sulfur on N-RGOS. The samples were characterized by XRD, TG, SEM and XPS. The electrochemical performance of N-RGOS@S as a cathode material for lithium-sulfur batteries was tested. The composites delivered a stable cyclic stability with a specific capacity of 549.8 mAh∙g⁻¹ maintained after 100 cycles at 0.1 C. And they also showed an excellent rate capa-bility that can reach 495.5 mAh∙g⁻¹ at 2 C. The excellent electrochemical performance is mainly at-tributed to the three-dimensional graphene network structure and nitrogen doping, which im-proves the conductivity of the electrode materials and hinders the diffusion of polysulfides during charging and discharging and reduces the shuttle effect.