高容量硅基负极材料及其厚膜成型技术和性能

Thick electrode forming technology and properties of high capacity silicon-based anode materials

摘要:

为了缓解硅基负极材料的体积膨胀并改善其电化学性能，以Mg、SiO和石墨为原料，成功制备出一种多相Si-MgO-G复合材料。探讨了不同高能球磨工艺对Mg和SiO反应程度的影响及厚膜成型技术的应用。结果表明，当高能球磨（1+5）h后，Mg和SiO原位反应生成Si-MgO产物，将反应产物与石墨混磨制备成多相Si-MgO-G复合材料。用XRD、SEM 和TEM等手段对制得材料的结构、形貌和成分进行分析，证实了复合材料是由Si、MgO和石墨组成，其中Si(220)//MgO(200)之间存在晶面共格关系。用CV和EIS等对捏合开炼厚膜技术制得负极极片进行电化学性能分析，结果表明，捏合开炼工艺制备的厚膜极片的厚度、载量和面积比容量分别约为薄膜极片的7.4倍、6.0倍和6.2倍。采用简单、绿色和可规模化生产的厚电极制备技术，可提高锂离子电池的面积比容量。

Abstract:

In order to alleviate Si volume expansion and achieve the improvement electrochemical properties , we have successfully prepared a multiphase Si-MgO-G composite material using Mg, SiO and graphite as raw materials. The effects of different high energy ball milling processes on the reaction degree of Mg and SiO were studied, and application of thick electrode forming technology was discussed in this paper. Researches showed that after high-energy ball milling for (1+5) h the in-situ redox reaction of Mg and SiO was fully completed to generate (Si+MgO) product. The reaction product was then mixed with Graphite to prepare multiphase Si-MgO-G composite materials. A combination of XRD, SEM, TEM, CV, and EIS was employed to study phase constitution, morphology and nanostructure, as well as electrochemical properties of the prepared silicon-based anode composite materials. It has been confirmed that the prepared SMG anode composite material was mainly composed of Si, MgO, graphite, and there existed an interface coherent relationship of Si(220)//MgO(200). The results show that the SMG-6h thick electrode was fabricated by kneading and open milling process, and the thickness and load of thick electrode were about 7.4 times and 6.0 times as compared to thin electrode. The corresponding area specific capacity of thick electrode was 6.2 times. This process demonstrates that thick electrode technique can be used to increase area specific capacity for Li-ion batteries through a simple, green and scalable route.