【作者】 陈顺鹏； 刘志亮； 郑捷； 李星国；

【Author】 Shunpeng Chen;Zhiliang Liu;Jie Zheng;Xingguo Li;College of Chemistry and Molecular Engineering, Peking University;

【机构】 北京大学化学与分子工程学院；

【摘要】 随着在便携式电子器件,光电子学,储能和传感等领域对锂离子电池性能的需求不断增加,1-3纳米硅以其卓越的理论比容量（3579 mAh×^g（-1）） ⁴而备受瞩目。纳米硅可以通过镁还原SiO₂制得。然而,传统的镁还原法通常需要600℃以上的高温,导致能耗高、副产物多。本文利用室温球磨法实现了金属镁对SiO₂的高效还原,以纳米镁和纳米SiO2为原料,10分钟内即可以化学计量比完全反应,有效避免了高温和长时间球磨造成的颗粒团聚。球磨得到的纳米硅表面具有高反应活性,可直接与正戊醇反应形成疏水的纳米溶胶,极大提高了分离效率,以超过85%的收率获得了平均粒径仅为40 nm的高品质纳米硅。经过简单的碳包覆后,这种硅基材料在2.1A·g^-1的电流下循环500圈后仍有1756 mAh·g^-1的比容量。进一步研究表明,添加少量的Mg₂Si可进一步提升室温球磨还原效率,以普通的商用镁粉为原料同样可以实现上述过程。粒径小于100 nm的纳米硅已在部分商用高能量密度的锂电池产品中得到应用,但目前小尺寸的纳米硅成本仍十分高昂。上述室温球磨法原料和设备成本低、能量效率高、易放大,是一种极具产业化前景的高品质纳米硅低成本制备技术。更多还原

【Abstract】 With the increasing demand for lithium-ion batteries（LIB） in the field of portable electronic devices photovoltaics, optoelectronics, energy storage and sensing, 1-3 Silicon nanostructures（nano-Si） are highly attractive due to their high theoretical lithium storage capacity(ca. 3579 mAh×g^-1).⁴Nano-Si can be prepared from silica through magnesium reduction. However, the reaction temperature of traditional magnesium reduction is always above 600℃, which results in the high consumption of energy and series of side products. In this study, the efficient reduction of silica by magnesium at ambient temperature is realized through ball milling. Using nanoparticles of Mg and silica as the reducing agent, the reaction is completed stoichiometrically within 10 min, which effectively avoids the aggregation of particles causing by long-time ball milling at high temperature. The obtained nano-Si with high surface reactivity can directly react with 1-pentanol to form hydrophobic colloid, which significantly improves the efficiency of separation. Nano-Si with an average diameter of 40 nm can be obtained with yield above 85%.⁵ After simple carbon coating, the nano-Si exhibit a high reversible capacity of 1756 mAh·g^-1 after 500 cycles at a current density of 2.1 A·g^-1. Recent study demonstrates that adding a small amount of Mg₂Si could increase the efficiency further. Besides, using commercial Mg can also complete the above process. Nano-Si within 100 nm has been applied in a portion of commercial high energy density lithium ion batteries production. However, the cost of small-size nano-Si is still prohibitively high. This promising method provide us an important progress towards cheap, high-energy-efficiency and scalable preparation of nano-Si.更多还原