亚5纳米二氧化钼/石墨烯复合材料的一步法制备及储锂性能研究

One-Step Synthesis and Lithium Storage Performance of Sub-5-nm MoO₂-Graphene Nanocomposites

摘要: 便携式电子设备和新能源汽车的快速发展对锂离子电池提出了更高的要求。MoO₂拥有高理论容量和低电阻率，有望取代商业化的石墨负极材料。本工作采用一步水热法制备了亚5纳米MoO₂/石墨烯复合材料。采用XRD、TEM和EDS对其物相和结构进行了表征。结果表明，抗坏血酸可将钼酸根还原为MoO₂，石墨烯可有效阻止晶粒团聚。采用恒流充放电、CV和EIS对其电化学性能进行了测试。首周可逆容量达1072.8 mAh∙g⁻¹，库仑效率为65.4%，循环100周后容量保持在579.6 mAh∙g⁻¹。MoO2颗粒的超小尺寸和石墨烯明显改善了电极的电子/离子传输并有效缓冲了体积膨胀。

Abstract: With rapid development of portable electronic devices and new energy vehicles, advanced lithium-ion batteries are required. MoO₂ has high theoretical capacity and low resistivity, and is expected to replace commercialized graphite anodes. Herein sub-5 nm MoO₂/graphene composites were prepared by one-step hydrothermal method. The phase and structure were characterized by X-ray diffraction, transmission electron microscopy and energy dispersive spectrometer, showing that ascorbic acid could reduce molybdate ions to MoO₂, while graphene could prevent the agglomeration of nanocrystals. The electrochemical performance was tested by galvanostatic charge-discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The initial reversible specific capacity was 1072.8 mAh∙g⁻¹ with coulombic efficiency of 65.4% and remained 579.6 mAh∙g⁻¹ after 100 cycles. The combination of sub-5 nm MoO₂ particles and graphene effectively improved the electron/ion transport and bufferd the volume expansion of electrodes.