还原氧化石墨烯/TiO2复合材料在钠离子电池中的电化学性能

二氧化钛(TiO₂)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TiO₂复合材料(GO/TiO₂), 通过热处理获得还原氧化石墨烯/TiO₂复合材料(RGO/TiO₂). 电化学测试结果表明, 还原氧化石墨烯改性的RGO/TiO₂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/TiO₂复合材料在各种电流密度下的可逆容量分别为183.7 mAh·g^-1 (20 mA·g^-1), 153.7 mAh·g^-1 (100 mA·g^-1)和114.4 mAh·g^-1 (600mA·g^-1), 而纯TiO₂的比容量仅为93.6 mAh·g^-1 (20 mA·g^-1), 69.6 mAh·g^-1 (100 mA·g^-1)和26.5 mAh·g^-1 (600mA·g^-1). 4.0%(w) RGO/TiO₂复合材料体现了良好的循环稳定性, 在100 mA·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 mAh·g^-1. 同等条件下, 纯TiO₂电极比容量只有68.8 mAh·g^-1. RGO包覆改性极大提高了TiO₂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.

Electrochemical Performances of Reduced Graphene Oxide/Titanium Dioxide Composites for Sodium-Ion Batteries

Anatase TiO₂ shows excellent long-term cycling stability as an anode for sodium-ion batteries. However, the low specific capacity and poor rate capability resulting from its intrinsic low electrical conductivity limit its applications. In this work, TiO₂ nanoparticles were coated with reduced graphene oxide (RGO) using a combination of spray-drying and heat treatment. Electrochemical tests showed that the obtained RGO/TiO₂ composites had improved electrochemical performances. The reversible capacities of the RGO/TiO₂ 4.0% (w)] composites were 183.7 mAh·g^-1 (20 mA·g^-1), 153.7 mAh·g^-1 (100 mA·g^-1), and 114.4 mAh·g^-1 (600 mA·g^-1). Bare TiO₂ showed low capacities of 93.6mAh·g^-1 (20mA·g^-1), 69.6mAh·g^-1 (100mA·g^-1), and 26.5mAh·g^-1 (600 mA·g^-1). The 4.0%(w) TiO₂/RGO composites exhibited good cycling stability with a charge capacity of 146.7 mAh·g^-1 at a current density of 100 mA·g^-1 after 350 cycles, compared with 68.8 mAh·g^-1 for bare TiO₂. RGO modification is a promising method for improving the electrochemical performances of the sodium energystorage materials.