MnO/石墨烯复合材料的制备及其作为锂离子电池负极的研究

Preparation and Electrochemical Performance of MnO/graphene Composite as Anode Materials for Lithium Ion Batteries

通过原位复合方法合成碳包覆MnO/石墨烯（C@MnO/GN）复合材料并探究其作为锂离子电池负极材料的电化学性能.扫描电子显微镜（SEM）以及透射电子显微镜（TEM）表征结果表明,MnO纳米颗粒（直径约为30~50nm）均匀分散在石墨烯片层上,且颗粒外面包裹一层厚度约为5nm的碳层.电化学测试结果表明该材料作为锂离子电池负极具有优异的倍率和循环性能.0.2和0.5A/g电流密度下,比容量分别为800和700mAh/g;10A/g电流密度下比容量仍能保持在372mAh/g;当电流密度调回0.5A/g时,其比容量仍能恢复到730mAh/g.该材料也表现出优异的循环性能,在5和10A/g电流密度下依次循环100圈,容量保持率几乎100%.

An in-situ synthetic strategy was developed to prepare carbon-wrapped MnO nanoparticles/graphene composite （C@ MnO/GN） and the composite was employed as an anode of lithium ion batteries. The results of scanning electron microscopy （SEM） and transition electron microscopy （TEM） displayed the uniform disperse of MnO nanoparticles on the graphene surface. The diameter of MnO nanoparticles is around 30-50 nm,and they are encapsulated by a carbon layer with a thickness of ~5 nm. The C@MnO/ GN composite showed excellent discharge capacity and cyclic stability. At the current density of 0.2 A/g and 0.5 A/g,the composite could deliver reversible capacities of 800 mAh/g and 700 mAh/g, respectively. Remarkably,it could still deliver a large capacity of ~372 mAh/g at a high current density of 10 A/g and then recover to ~730 mAh/g when the current density was switched back to 0.5 A/g after 35 cycles with different current densities imposed. The composite also exhibited superior cyclic stability at successively high current densities of 5 A/g and 10 A/g.