二氧化钛(Ti O2)作为有前景的钠离子电池负极材料,具有良好的循环稳定性,但由于其导电率较低,而导致容量和倍率性能不佳限制了其实际应用.本文采用喷雾干燥技术制备了氧化石墨烯/纳米Ti O2复合材料(GO/Ti O2),通过热处理获得还原氧化石墨烯/Ti O2复合材料(RGO/Ti O2).电化学测试结果表明,还原氧化石墨烯改性的RGO/Ti O2复合材料的电化学性能得到显著提升,RGO含量为4.0%(w)的RGO/Ti O2复合材料在各种电流密度下的可逆容量分别为183.7 m Ah?g-1(20 m A?g-1),153.7 m Ah?g-1(100 m A?g-1)和114.4 m Ah?g-1(600m A?g-1),而纯Ti O2的比容量仅为93.6 m Ah?g-1(20 m A?g-1),69.6 m Ah?g-1(100 m A?g-1)和26.5 m Ah?g-1(600m A?g-1).4.0%(w)RGO/Ti O2复合材料体现了良好的循环稳定性,在100 m A?g-1电流密度下充放电循环350个周期后,比容量仍然保持146.7 m Ah?g-1.同等条件下,纯Ti O2电极比容量只有68.8 m Ah?g-1.RGO包覆改性极大提高了Ti O2在钠离子电池中的电化学嵌钠/脱钠性能.RGO包覆改性技术在改进钠离子电池材料性能中将有很好的应用前景.
A novel Co(phen)2/C catalyst was prepared by coating cobalt(II) phenanthroline (phen) chelate on BP2000 carbon black and then heat treating in an inert atmosphere. The obtained Co(phen)2/C product with 1.0 wt% cobalt loading exhibits similar morphology and porosity characteristics to those of the bare BP2000. X-ray diffraction measurements demonstrate a face-centered cubic (fcc) α-Co phase embedded in the carbon support after pyrolysis. Charge/discharge tests of the lithium-oxygen cells using the prepared Co(phen)2/C catalyst show high discharge capacities of 4870 mAh g-1 (0.05 mA cm-2 ), 3353 mAh g-1 (0.1 mA cm-2 ) and 3220 mAh g 1 (0.15 mA cm-2 ), respectively. The Co(phen) 2 /C cathode exhibits reasonable reversibility with capacity retention of 1401 mAh g-1 ( 0.1 mA cm-2 ) after 10 cycles. The superior electrochemical performance of the prepared Co(phen)2/C catalyst and low cost of the phenanthroline chelating agent indicate that Co(phen)2/C is a promising cheap catalyst for lithium-air batteries.
WANG HongLIAO XiaoZhenJIANG QiZhongYANG XiaoWeiHE YuShiMa ZiFeng
