单纯的炭气凝胶(CA)与SiO球磨后可以制得性能优异的复合材料CA-SiO, 实验研究了球磨时间和球磨转速等工艺条件对CA-SiO的结构和电化学性能的影响. 结果表明, 无定形态的SiO与CA球磨后, 逐渐有晶粒细小的Si晶体析出, Si的晶粒随球磨时间的延长或球磨转速的提高先减小然后增大, Si的结晶度随球磨时间的延长或球磨转速的提高而增强, 但过长的球磨时间或过快的球磨转速均会导致材料中的晶体Si向非晶态转变; 球磨使材料中C的晶粒有所增大, 但球磨时间和球磨转速对C的晶粒大小没有明显的影响; CA-SiO中Si的结晶度越高、晶粒越小, 材料的嵌脱锂容量越高、充放电循环稳定性越好, 非晶态Si的存在不仅不利于锂离子在CA-SiO中的嵌入和脱出, 而且会导致材料的循环稳定性变差. 将CA-SiO用作锂离子电池负极材料时, 其最佳的制备工艺为: 以400r/min的速度球磨10h.
Carbon aerogel (CA)-SiO with excellent lithium insertion-extraction property could be prepared through ball-milling of carbon aerogel (CA) with SiO. Effects of ball-milling process including ball-milling time and ball-milling speed on structure and electrochemical property of CA-SiO composite were investigated. The results show that ball-milling of amorphous SiO with CA can crystallize Si with small particle size, the crystal size of Si increases with the extension of ball-milling time and the increase of ball-milling speed, and then decreases. The crystallization of Si can be improved by the extension of ball-milling time and the increase of ball-milling speed. However, ball-milling for too long time or at too high speed will result in transformation of crystal Si to amorphous. Little influence of ball-milling time and ball-milling speed is found on crystal size of C in the prepared CA-SiO, though ball-milling leads to some increase of C crystal size. CA-SiO has higher capacity and better cycling stability when the silicon within this material shows higher crystallization and smaller crystal size. In contrast, amorphous Si is disadvantageous for lithium insertion-extraction in CA-SiO which will lead to poorer cycling stability. The ball-milling speed of 400r/min and the ball-milling time of 10h are the best preparation parameters for CA-SiO used as anode material of lithium-ion battery.
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