【摘要】 采用磁控溅射法在铜箔集流体上沉积了具有"三明治"结构的Si/Al/Si三层薄膜.高分辨率透射电镜(HRTEM)和选区电子衍射(SAED)分析结果表明,该薄膜为非晶态.扫描电镜(SEM)和能量散射X射线能谱(EDS)结果表明,该薄膜总厚度约为4.0μm,循环100周后体积膨胀率为225%.在1.5～0.005V(vs.Li+/Li)和0.1mA/cm2条件下,该薄膜电极前5周衰减较快,而后趋于平缓.首次放锂量为0.88mA.h/cm2,循环5周后,放锂量为0.71mA.h/cm2,100周后的放锂量仍能保持在0.61mA.h/cm2.研究结果表明,Al的加入有效地抑制了Si膜的体积膨胀,使之具有良好的循环寿命.交流阻抗结果表明,随着循环次数的增加,极化电阻首先从46.9Ω.cm2(第1周)降低到36.2Ω.cm2(第50周),而后又升高到47.3Ω.cm2(第100周).Al的加入提高了Si膜的导电性,有效地降低了其极化电阻,改善了Si膜的电压滞后现象.更多还原

【Abstract】 A sandwich-type Si/Al/Si film was prepared on copper substrate by magnetron sputtering.High-resolution transmission electron microscopy(HRTEM) and selected area electron diffraction(SAED) results indicat that the sputtered film had an amorphous structure.Cross-sectional scanning electron microscope(SEM) images and energy dispersive X-ray spectrometry(EDS) spectra show that the thickness of the film was about 4.0 μm,and its expansion ratio was up to 225% after 100 cycles.In the potential range 1.5—0.005 V(vs.Li+/Li) at the current density of 0.1 mA/cm2,this film anode exhibited an initial capacity around 0.88 mA·h/cm2,0.71 mA·h/cm2 after 5 cycles,and still retained over than 0.61 mA·h/cm2 after 100 cycles.The addition of Al to Si effectively suppressed the volume expansion,which led to a prolonged cycle life.Electrochemical impedance spectroscope(EIS) results indicat that the polarization resistance first decreased to 36.2 Ω·cm2(50th cycle) from 46.9 Ω·cm2(1st cycle) and later increased to 47.3 Ω·cm2(100th cycle) during cycling.The introduction of Al to Si improved the conductivity of the Si film and reduced the polarization resistance,which suppressed the voltage hysteresis effect.更多还原