Zuo Xiuxia, Yang Qinghua, He Yaolong, Cheng Ya-Jun, Yin Shanshan, Zhu Jin, Müller-Buschbaum Peter, Xia Yonggao
Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, 1219 Zhongguan West Rd., Ningbo 315201, China.
Shanghai Institute of Applied Mathematics and Mechanics, School of Mechanics and Engineering Science, Shanghai University, Shanghai 200444, China.
Molecules. 2022 Nov 2;27(21):7486. doi: 10.3390/molecules27217486.
Porous silicon-based anode materials have gained much interest because the porous structure can effectively accommodate volume changes and release mechanical stress, leading to improved cycling performance. Magnesiothermic reduction has emerged as an effective way to convert silica into porous silicon with a good electrochemical performance. However, corrosive HF etching is normally a mandatory step to improve the electrochemical performance of the as-synthesized silicon, which significantly increases the safety risk. This has become one of the major issues that impedes practical application of the magnesiothermic reduction synthesis of the porous silicon anode. Here, a facile HF-free method is reported to synthesize macro-/mesoporous silicon with good cyclic and rate performance by simply increasing the reduction temperature from 700 °C to 800 °C and 900 °C. The mechanism for the structure change resulting from the increased temperature is elaborated. A finite element simulation indicated that the 3D continuous structure formed by the magnesiothermic reduction at 800 °C and 900 °C could undertake the mechanical stress effectively and was responsible for an improved cyclic stability compared to the silicon synthesized at 700 °C.
多孔硅基负极材料备受关注，因为其多孔结构能够有效缓冲体积变化并释放机械应力，从而提升循环性能。镁热还原法已成为一种将二氧化硅转化为具有良好电化学性能的多孔硅的有效方法。然而，腐蚀性的氢氟酸蚀刻通常是提高合成硅电化学性能的必要步骤，这显著增加了安全风险。这已成为阻碍镁热还原合成多孔硅负极实际应用的主要问题之一。在此，报道了一种简便的无氢氟酸方法，通过将还原温度从700℃简单提高到800℃和900℃来合成具有良好循环和倍率性能的大孔/介孔硅。阐述了温度升高导致结构变化的机理。有限元模拟表明，800℃和900℃下镁热还原形成的三维连续结构能够有效承受机械应力，与700℃合成的硅相比，其循环稳定性得到了提高。
