Huang Hsin-Che, Huang Bo-Chen, Hsu Hsiao-Ping, Lan Chung-Wen
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
ACS Omega. 2023 Jan 19;8(4):4165-4175. doi: 10.1021/acsomega.2c07242. eCollection 2023 Jan 31.
Silicon is an important anode material for lithium-ion batteries because of its high theoretical capacity. However, the large volume expansion of silicon anodes hinders its commercial utilization. As an alternative, silicon oxycarbides (SiOCs) mitigate the expansion of anodes during lithiation, and the synthesis of SiOC beads from silanes is rather simple and at a low cost. In this study, we compared three different reactor setups for making the SiOC beads from methyltrimethoxysilane (MTMS) and found that the control of residence time was crucial. Thereby, the batch reactor turned out to be the easiest one for making monodispersed beads. We also reduced the O/Si ratio of the SiOC beads by adding dimethyldimethoxysilane (DMDMS) for better battery performance. The first-cycle delithiation capacity of the most stable material was over 1796 mA h/g, with an initial Coulombic efficiency of 82%, while the capacity retention after 170 cycles was 67% (992 mA h/g) at a charging rate of 2 A/g in the potential range of 0.01-3 V. This was among the best of the reported data so far for the SiOC beads from MTMS.
硅因其高理论容量而成为锂离子电池的重要负极材料。然而，硅负极的大幅体积膨胀阻碍了其商业应用。作为一种替代材料，碳氧化硅（SiOCs）可减轻锂化过程中负极的膨胀，并且由硅烷合成SiOC珠相当简单且成本低廉。在本研究中，我们比较了三种由甲基三甲氧基硅烷（MTMS）制备SiOC珠的不同反应器设置，发现控制停留时间至关重要。因此，间歇式反应器被证明是制备单分散珠最简单的一种。我们还通过添加二甲基二甲氧基硅烷（DMDMS）降低了SiOC珠的O/Si比，以获得更好的电池性能。最稳定材料的首次循环脱锂容量超过1796 mA h/g，初始库仑效率为82%，而在0.01 - 3 V的电位范围内以2 A/g的充电速率进行170次循环后的容量保持率为67%（992 mA h/g）。这是迄今为止报道的由MTMS制备的SiOC珠的最佳数据之一。
