原料配比对合成一氧化锰/碳微球结构和性能的影响

Effects of the mix ratio of raw materials on structure and performance of porous MnO/C microspheres

以氯化胆碱-乙二醇低共熔溶剂为反应介质,采用沉淀法制备了锂离子电池负极材料一氧化锰/碳多孔微球,并用X射线衍射(XRD)、扫描电镜(SEM)、比表面积及孔径分析、恒电流充放电技术、电化学阻抗谱和循环伏安等手段,研究了碳酸氢铵与氯化锰物质的量比对一氧化锰/碳材料的形貌、结构及电化学性能的影响。结果表明,一氧化锰/碳材料的比表面积、孔径、孔体积、比容量、循环性能和倍率性能均随着碳酸氢铵与氯化锰物质的量比的增加而先增大后减小,碳酸氢铵与氯化锰物质的量比为2.0∶1时制备的一氧化锰/碳材料为多孔球体颗粒,粒径为0.5~2.5μm、平均孔径为11.5 nm、比表面积高达127.7 m2/g。一氧化锰/碳多孔微球材料在1C测试条件下的放电比容量为830 m A·h/g,循环50次后容量保持率接近100%,具有较高的比容量和较好的循环性能。

Porous Mn O/C microspheres,used as anode materials for lithium ion batteries were synthesized by precipitation method with chloride/ethylene glycol-based deep eutectic solvent(DES) as the reaction medium.The effects of the amountof-substance ratio of NH4 HCO3 and Mn Cl2·4 H2 O on the structure,morphology and electrochemical properties of the Mn O/C composites were investigated by X-ray diffraction,scanning electron microscopy,specific surface and pore size tests,galvanostatic charge-discharge tests,electrochemical impedance spectra and cyclic voltammetry(CV).The results showed that the BET surface area,pore size,pore volume,special capacity,cycle-stability and rate performance of the prepared Mn O/C first increased and then decreased with the increase of the amount-of-substance ratio of NH4 HCO3 and Mn Cl2·4 H2 O.The Mn O/C composites prepared with the amount-of-substance ratio of 2 ∶1 were porous microspheres with a diameter at 0.5 ~2.5 μm,which had an average pore size of 11.5 nm and a BET surface area of 127.7 m2/g.The prepared porous Mn O/C microspheres delivered a discharge capacity of 830 m A·h/g with a capacity retention ratio of approximately 100% after 50 cycles at 1 C,thus exhibiting a good rate performance and cycle stability.