Preparation of three-dimensional hierarchical porous carbon microspheres for use as a cathode material in lithium-air batteries
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摘要: 以尿素与甲醛为原料，在酸性条件下沉淀聚合制备脲醛树脂微球。随后进行预氧化、高温热处理制备炭微球。探究了脲醛比、固化剂浓度对炭微球形貌、结构和比表面积的影响。采用扫描电镜、透射电镜、N2吸附等手段对所得产品的形貌与孔结构进行了表征。结果表明：当脲醛比为1∶0.8，固化剂浓度为0.5 M时，制备得到粒径分布均一、分散性好、球形度高的炭微球。其比表面积为498 m2·g-1。通过活化处理，比表面积提高为827 m2·g-1。用于锂空气电池的正极材料，在电流密度为100 mA·g-1时，首次充放电比容量达到2 017 mAh·g-1和2 075 mAh·g-1。Abstract: Urea-formaldehyde resin microspheres were prepared by a polymerization method using urea and formaldehyde as the raw materials and hydrochloric acid as the catalyst. The microspheres were pre-oxidized and carbonized to obtain carbon microspheres, then activated with KOH. The morphology and pore structure of products were characterized by SEM, TEM and N2 adsorption. Results indicate that the microstructure of the microspheres is highly dependent on the mass ratio of urea to formaldehyde and the concentration of hydrochloric acid. The specific surface area of the carbon microspheres is 498 m2·g-1, which is increased to 827 m2·g-1 after KOH activation. When used as the electrode materials of lithium-air batteries, the initial charge and discharge capacities are 2 017 and 2 075 mAh·g-1, respectively, at a current density of 100 mA·g-1.
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Key words:
- Urea-formaldehyde resin /
- Carbon microspheres /
- Activation /
- Li-air battery
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