以高锰酸钾和抗坏血酸合成的MnC2O4·2H2O为前驱体,通过固相烧结制备了纳米MnO材料.分别采用X射线衍射(XRD)、扫描电子显微镜(SEM)和恒电流充放电技术考察了其晶相结构、颗粒形貌和电化学性能.分析结果表明,该纳米MnO具有面心立方的岩盐结构,结晶度良好.其颗粒是由粒径为50-100 nm的一次颗粒结合而成的二次颗粒,大小约为400-600 nm.当充放电电流密度为46.3 mA·g-1时,纳米 MnO 的首次库仑效率可达68.9%,可逆比容量为679.7 mAh·g-1.在141.1 mA·g-1的电流密度下循环50圈后,比容量由584.5 mAh·g-1降至581.5 mAh·g-1,容量保持率高达99.5%,表现出优异的循环性能.此外,当电流密度增加到494.7 mA·g-1(~2C)时,其比容量依然可达290 mAh·g-1,表现出较好的倍率性能和快速充放电能力.因此,纳米MnO具有比容量高、循环稳定、倍率性能好和安全环保等优点,是一种非常有前景的锂离子电池负极材料.%Transition metal oxides, especial y manganese monoxide (MnO), are being intensively studied as candidate anode materials for next generation lithium-ion batteries in high efficiency energy storage applications such as portable electronics, electric vehicles, and stationary electricity storage. In this paper, the MnC2O4·2H2O precursor, prepared from KMnO4 and ascorbic acid, was heat-treated to synthesize nano MnO by a solid-state reaction approach. X-ray diffraction (XRD) showed that the so-obtained MnO had a rock-salt structure with good crystal inity, and scanning electron microscopy (SEM) indicated that the primary particle size was about 50-100 nm, while the secondary particle size was about 400-600 nm. As an active material for lithium-ion batteries, the nano MnO material delivered a reversible capacity of 679.7 mAh·g-1 with an initial columbic efficiency of 68.9% at a current density of 46.3 mA·g-1. The specific discharge capacity slightly decreased from 584.5 to 581.5 mAh·g-1 with a retention of 99.5% after 50 cycles at a current density of 141.1 mA·g-1. Moreover, the material was able to release a capacity of 290 mAh·g-1 at current densities as high as 494.7 mA·g-1 (corresponding to ~2C), which demonstrates reasonable rate performance and moderately fast charge/discharge capabilities. Al of the above characteristics make nano MnO promising anode materials for developing high-capacity, long-life, low-cost, and environmental y-friendly lithium-ion batteries.
展开▼
