超细Sn和SnO_2与碳复合的锂离子电池负极材料的制备及其电化学性能

采用溶液法以SnCl4.5H2O和葡萄糖为原料合成了颗粒尺寸为几个纳米的超细Sn及SnO2颗粒分布于无定形碳基体的复合材料,并在溶液过程中引入少量石墨。采用XRD、SEM和TEM等材料结构分析方法和恒电流充放电等电化学测试方法分析研究了前驱体的煅烧温度和石墨的引入对获得产物的结构及其作为锂离子电池负极材料的电化学性能的影响。研究结果表明,在500～700℃的煅烧温度下获得的Sn/C及含少量SnO2的Sn/SnO2/C复合材料,由于其中的Sn及SnO2的超细纳米尺寸及碳基体的缓冲有效减小了Sn在脱嵌锂过程中的应变和粉化,使材料具有良好的循环性能。石墨的引入有效提高了复合材料的容量和循环稳定性。经500℃煅烧的复合电极材料相对于其它材料具有更高的容量,其首次可逆容量达520mAh/g,经初始几个循环后,容量趋于稳定,经100次循环后,容量保持在350mAh/g。

Synthesis and Electrochemical Properties of Ultrafine Sn and SnO2 Dispersed Carbon Matrix Composite Anode Materials for Li-ion Batteries

Ultrafine Sn and SnO2 dispersed carbon matrix composites have been synthesized by a simple solution method using SnCl4·5H2O and glucose as starting materials.Minor graphite is introduced in the composites during the solution process.The size of the Sn and SnO2 particles is of several nanometers.Effects of calcination temperature and the addition of graphite on the structure and the electrochemical properties of the composites as the anode material for lithium batteries have been studied by using X-ray diffractometry(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and electrochemical testing of galvanostatic charge-discharge,etc.The results show that the Sn/C and Sn/SnO2/C composites calcined in the temperature range of 500~700℃ show favorable cycle stability due to the reduced stress of Sn and SnO2 during lithiation and delithiation which is attributed to the ultrafine size of Sn as well as SnO2 and the buffer from the carbon matrix.The introduction of graphite effectively improves the capacity and the cycle stability due to that it can reduce the particle size of the composites.The composite obtained at calcination temperature of 500℃ provides an initial reversible capacity of 520mAh/g and maintains a capacity of 350mAh/g after 100 cycles,which is higher than others.