CaTi2O4(OH)2片状结构向CaTiO3片状结构转化及其性能研究

Studies on CaTi_2O_4(OH)_2 Nanosheets Transformation into CaTiO_3 Nansheets and Its Properties

通过控制水含量,用水热法制备了CaTi2O4(OH)2片状结构。通过对水含量为50 mol条件下所制备的CaTi2O4(OH)2片状结构煅烧来制备CaTiO3片状结构。当热处理温度≤400℃,CaTi2O4(OH)2纳米片状结构稳定存在。当热处理温度为650℃和750℃,制备了CaTiO3片状结构。采用XRD、SEM和TEM等测试方法对片状结构进行表征,并对CaTi2O4(OH)2片状结构向CaTiO3片状结构转化的反应过程和形成机理进行分析。在热处理温度400℃时,样品的首次放电比容量最大,可达到168.5 mAh/g。当热处理温度继续升高到650℃和750℃,样品的首次充放电容量分别为18.9 mAh/g和5 mAh/g。这说明发育完善的CaTi2O4(OH)2片状结构有利于电化学过程中离子的嵌入和脱出。

By controlling water content,pure CaTi2O4（OH）2nanosheets were prepared by a hydrothermal method. CaTi2O4（OH）2nanosheets synthesized at 50 of water molar were heated at different temperature. When the temperature is lower than 400 ℃,CaTi2O4（OH）2structure keep unchanged,indicating it may keep steady at room temperature. Further increasing the temperature to 650 ℃ and 700℃,CaTiO3 nansheets are obtained. The microstructure of the samples were investigated by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,and transmission electron microscopy（TEM）. The formation mechanism of CaTiO3 changed from CaTi2O4（OH）2is proposed.When the heat temperature is 400 ℃,the initial discharge capacity of the sample is 168. 5 mAh /g.Further increasing the temperature to 650 ℃ and 700 ℃,the discharge capacity of the sample is 18. 9and 5 mAh /g,respectively. It indicates that CaTi2O4（OH）2nanosheets are available for lithium ions insertion and dis-insertion.