一步硫/磷热处理制备空心Co9S8/CoP/C纳米复合材料及其储钠性能研究

低成本、高性能的钠离子电池有望成为代替锂离子电池的下一代核心器件.但是开发出高比容量、高倍率的钠离子电池负极材料依然是瓶颈.本文通过水热/溶剂热法制备了Co基前驱体,然后将其一步硫/磷热处理制得具有空心多孔结构的h-Co₉S₈/CoP/C纳米复合材料.通过X-射线粉末衍射(XRD)、拉曼光谱(Raman)、扫描电镜(SEM)、透射电镜(TEM)和X-射线光电子能谱(XPS)等表征以确定纳米复合物的物相以及形貌特征.当h-Co₉S₈/CoP/C作为钠离子电池负极材料时,该电极材料展示了高的比容量(561 mAh g^-1@0.1 Ag^-1)、较好的循环性能(可逆比容量200 mAh g^-1@2 Ag^-1)和倍率性能.h-Co₉S₈/CoP/C之所以显示出良好的储钠性能,主要得益于其空心多孔结构不仅提供更多的空间缓解钠在反复嵌入和脱出过程造成的体积膨胀效应,而且可以缩短离子/电荷扩散途径以加快反应动力学,此外,Co₉S₈、CoP和C独特的电子结构优势得以共同发挥.

Synthesis of hollow CoS/CoP/C microspheres by one-step sulfur/phosphorus heat treatment with high-performance sodium-ion batteries

Low-cost and high-performance sodium-ion batteries(SIBs)are expected to represent a promising alternative to the lithium-ion battery.However,the lack of high-performance anode materials of SIBs is still one of the bottlenecks.In this paper,the h-Co9S8/CoP/C nanocomposite with a hollow porous structure was prepared by two steps,which includes that a Co-based precursor was synthesized via a simple hydrothermal method,followed by simultaneous sulfurization and phosphorization reaction.X-ray diffraction(XRD),Raman spectrum,scanning electron microscopy(FESEM),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS)were used to characterize and analyze the phase and morphology of the nanocomposite.When h-Co9S8/CoP/C was used as the anode material of SIBs,it exhibited high specific capacity(561 mAh g^-1 at 0.1 A g^-1),good cycle performance(the reversible specific capacity is 200 m Ah g^-1 at 2 A g^-1)and rate performance.The excellent Na storage performances of h-Co9S8/CoP/C can be mainly attributed to the hollow porous structure,which can not only provide more space to alleviate the volume expansion effect during cycling,but also shorten the ion/charge and accelerate the reaction kinetics.Moreover,it is also attributed to the unique electronic structures of Co9S8,CoP and C that play their advantages together.