聚吡咯包覆MoS_(2)/生物质碳复合材料的制备及电化学储钠性能研究

Preparation and sodium storage performances of PPy-coated biomass-derived carbon/MoS_(2) composites

为了解决二硫化钼(MoS_(2))作为钠离子电池负极材料容量衰减快、倍率性能差的问题,通过简单的一步水热法在木棉花瓣生物质碳(PC)骨架上原位生长MoS_(2),并在材料表面包覆一层聚吡咯(PPy),制备形成了PC/MoS_(2)@PPy复合材料。利用SEM、XRD、Raman与TG等表征技术分析了材料的形貌、结构以及成分,并通过组装半电池测试了其作为钠离子电池负极时的电化学性能。结果表明,层间距扩展至0.98 nm的MoS_(2)纳米片均匀地负载在层状网络结构的生物质碳骨架上,并采用PPy作为包覆层构建了PC/MoS_(2)@PPy三元夹心结构复合材料,这种层状夹心结构不仅提供了大量电化学反应活性位点,而且有效缓解了MoS_(2)在长循环过程中的体积变化,生物质碳骨架联合PPy构成的三维导电网络有效提升了电极材料的导电性,促进电化学反应动力学。因此,PC/MoS_(2)@PPy电极在0.1 A/g的电流密度下,首次放电容量高达652.9 mAh/g,循环100圈后比容量仍然保持在394 mAh/g,可逆容量保持率维持在91%。

To solve the problems of fast capacity decay and poor rate performance of MoS_(2) as anode material of sodium-ion batteries(SIBs),herein,a simple one-step hydrothermal method was used to grow MoS_(2) in situ on the petals biomass carbon(PC)skeleton of kapok,and a layer of polypyrrole(PPy)was coated on the material surface to prepare PC/MoS_(2)@PPy composite.A series of characterization tests,such as SEM,XRD and Raman,were used to analyze the morphology,structure and composition,and the electrochemical performances of the material as the anode material of SIBs were tested by assembling the half-cells.The results show that the MoS_(2) nanosheets with extended layer-spacing of 0.98 nm are uniformly loaded on the layered-network skeleton of PC,together with the PPy coating layer forming the PC/MoS_(2)@PPy composite.This layered sandwiched structure provides a large number of reactive sites for electrochemical sodium storage and effectively alleviates the volume variation of MoS_(2) in the long cycling process.The three-dimensional conductive network composed of biomass carbon skeleton and PPy also effectively improves the electrical conductivity of the electrodes and accelerates the reaction kinetics of the electrode material.Therefore,the initial discharge capacity of the electrode is up to 652.9 mAh/g at 0.1 A/g,the specific capacity still remains at 394 mAh/g after 100 cycles and the capacity retention rate is maintained at 91%.