鋰電池碳矽氧負極材料的高壓製備方法之研究

Pressure‐Induced Vapor Synthesis of SiOC Material for Lithium Ion Battery Anode

余皓庭(Hao-Ting Yu)

指導教授 ： 藍崇文

國立臺灣大學/工學院/化學工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202104215

摘要

氧化矽作為新一代的負極材料，可滿足傳統石墨材料所無法達成的電動交通工具與大型儲能設備對電池的高能量密度需求，工業上氧化矽需經過加工磨碎至微米等級以下才可進一步進行鍍碳等程序來作為負極材料使用，磨碎的過程易受汙染且耗費能源。有一種方法是以聚二甲基矽氧烷(PDMS)作為原料於密閉容器內進行高溫熱處理，PDMS在密閉容器內升溫裂解所產生的高壓可使轉化的SiOC材料以球形的結構生成，可直接製備出數微米大小的球形SiOC材料無須額外加工。
在本論文中將該實驗的規模從5 ml反應器放大至300 ml的高壓釜，大幅提升產量，並且透過添加催化劑NiCl2將其反應溫度從文獻的800度降低至650度，降低高壓釜材料的耐溫需求使其可用一般的不鏽鋼材，並且觀察反應過程中溫壓變化，確認了催化劑加速了前驅物在升溫過程中的裂解，於持溫4小時達到最高壓力170 kg/cm2。40 g純PDMS在催化劑20% NiCl2以10⁰C/min升溫至650⁰C持溫4小時後可得到平均6.63 um分散性佳的球形SiOC產物；產率66.1%，產物經1100⁰C 6小時燒結後的SiOx/C材料首圈放電電容為1529 mAh/g，首圈庫倫效率64.5%，無須研磨加工可直接作為負極材料使用。

關鍵字

高壓合成 ； 球形SiOx/C ； 游離碳 ； 負極材料 ； 鋰電池

並列摘要

Compared with tradition graphite anode with lower capacity, silicon oxide can meet higher energy density requirements such as electric vehicles and energy storage equipment. In industry, silicon oxide needs to be grinded into smaller pieces in several microns before carbon coating as anode material. However, grinding process may contamitate material and consume energy. There is a method of synthesizing subnanoscopical SiOx/C spheres by heating polydimethylsiloxane (PDMS) in a sealed container. The high pressure generated by heating and cracking of PDMS in the sealed container induced the formation of spherical morphology. Spherical SiOx/C materials in several microns can be used as anode material without additional grinding process.
In this paper, we scale up the synthesis process from a 5 ml reactor to a 300 ml autoclave, which greatly increases the total product. By adding the catalyst nickel chloride, the reaction temperature was reduced from 800 degrees in the literature to 650 degrees, and the material requirement for autoclave was reduced. Lower temperature makes it possible to use ordinary stainless steel for autoclave. The temperature and pressure changes during the reaction are observed, confirming that the catalyst accelerates the cracking rate of the precursor during the heating process with the maximun pressure 170 kg/cm2. 40 g of pure PDMS with catalyst 20% NiCl2 are heated at 10⁰C/min to 650⁰C for 4 hours and homogeneously dispersed SiOC spheres are synthesized which are 6.63 um in average and the yield is 66.1%. The SiOx/C material exhibits first discharge capacity 1529 mAh/g and ICE 64.5%, which can be used directly as anode material without grinding process.

並列關鍵字

high pressure synthesis ； SiOx/C sphere ； free carbon ； anode ； lithium-ion battery

參考文獻

Armand, M., Tarascon, JM. Building better batteries. Nature 451, 652–657 (2008).

Michael M. Thackeray, Christopher Wolverton, Eric D. Isaacs, Electrical energy storage for transportation—approaching the limits of, and going beyond, lithium-ion batteries, Energy Environ. Sci. 5, 7854 (2012)

Chan, C., Peng, H., Liu, G. et al. High-performance lithium battery anodes using silicon nanowires. Nature Nanotech 3, 31–35 (2008)

Ke Pan, Feng Zou, Marcello Canova, Yu Zhu, Jung-Hyun Kim, Systematic electrochemical characterizations of Si and SiO anodes for high-capacity Li-Ion batteries, Journal of Power Sources, Volume 413, (2019) Pages 20-28

Liurong Shi, Chunlei Pang, Shulin Chen, Mingzhan Wang, Kexin Wang, Zhenjun Tan, Peng Gao, Jianguo Ren, Youyuan Huang, Hailin Peng, and Zhongfan Liu, Vertical Graphene Growth on SiO Microparticles for Stable Lithium Ion Battery Anodes, Nano Lett. (2017) 17, 6, 3681–3687