Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect  

作　　者：Jianxin Tu Shuo Yu Kui Hao Le Sun Ruicheng Bai Fangzhou Zhang Aijun Li Hong Liu 

机构地区：[1]Institute of Materials,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China [2]Department of Applied Physics,The Hong Kong Polytechnic University,Kowloon 999077,Hong Kong,China [3]Shaoxing institute of technology,Shanghai University,Shanghai 200444,China

出　　处：《Nano Research》2024年第9期7814-7823,共10页纳米研究（英文版）

基　　金：support by the financial support from the National Nature Science Foundation of China(No.12002196);Natural Science Foundation of China(No.12102140).

摘　　要：In this study,we successfully synthesized silicon nanotubes(Si-NTs)and silicon nanowires(Si-NWs)in a controllable manner using a catalyst-and template-free method through the direct electrolysis of SiO_(2)in a molten CaCl_(2)-CaO system,while also proposing a novel formation mechanism for Si-NTs.Si-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO_(2)decomposition voltage.By subsequently adjusting the voltage to a value between the decomposition potentials of CaCl_(2)and CaO,in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs,leading to the formation of a Ca layer.The formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs,as the outward diffusion rate of Si exceeds the inward diffusion rate of Ca.These differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall effect.These vacancies gradually accumulate and merge,forming large voids,which ultimately result in the formation of hollow SiCa-NTs.Through a subsequent dealloying process,the removal of the embedded calcium leads to the formation of Si-NTs.Following the application of a carbon coating,the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g^(-1)at 1.5 A·g^(-1)and exhibits exceptional long-term cycling stability,maintaining a capacity of 977 mAh·g^(-1)after 2000 cycles at 3.0 A·g^(-1).

关 键 词：silicon nanotubes silicon nanowires lithium-ion battery Kirkendall effect 

分 类 号：TB383[一般工业技术—材料科学与工程]