一步水热法制备纳米SnO2@C复合材料及其储锂性能研究

One Step Hydrothermal Preparation of SnO2@C Composite and Its Lithium Storage Performance

以两种糖类化合物(葡萄糖与水溶性淀粉)为碳源,以SnCl4.5H2O为锡源用一步水热法制备了SnO2@C复合物。使用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、N2吸脱附法和透射电镜(TEM)表征其组成和微观结构,并采用恒电流充放电测试、循环伏安法(CV)和电化学阻抗谱(EIS)表征其作为锂离子电池负极材料的电化学性能。结果表明,糖类前驱体衍生的热解炭和直径为4~5 nm的SnO2纳米点生成了稳定的复合结构,炭基体的缓冲作用和材料纳米化缓解了SnO2的体积膨胀效应,使材料的结构稳定性和电化学性能提高。由于葡萄糖热解炭的有序度比淀粉热解炭更高,这组试样具有更好的循环性能和倍率性能,在2 A/g大电流密度下其比容量高于400 mAh/g。

Two kinds of SnO2@C composite were successfully prepared by a facile and cost-effective method through one-pot hydrothermal treatment of a mixture of Sn4+,and different carbohydrates(glucose and starch).The composition and microstructure of resultants were characterized by X-ray Diffraction(XRD),Fourier Transform Infrared Spectroscopy(FTIR),N2 Adsorption-desorption method and Transmission Electron Microscope(TEM).The electrochemical performance as anode material for lithium-ion batteries was confirmed by galvanostatic charge-discharge test and Cyclic Voltammetry(CV)method.Results show that the pyrolytic carbon derived from carbohydrate precursors forms a stable composite structure with 4~5 nm SnO2 nanocrystals.The large volume variation of SnO2 during the Li+insertion-extraction process is effectively alleviated by the buffering effect of carbon matrix.Whatsmore,small SnO2 nanoparticles can also effectively reduce this volume change,improving the electrode structural stability and electrochemical properties.Because the degree of order of glucose pyrolytic carbon is higher than that of starch pyrolytic carbon,correspondingly its composite shows better cycle and rate performance,which can stably release>400 mAh/g specific capacity at high current density of 2 A/g.