Zhu Jiakun, Guo Mohan, Liu Yuemei, Shi Xiaobo, Fan Feifei, Gu Meng, Yang Hui
Department of Mechanics , Huazhong University of Science and Technology , Wuhan , Hubei 430074 , China.
Department of Material Science and Engineering , Southern University of Science and Technology, & Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices , No. 1088 Xueyuan Blvd , Shenzhen , Guangdong 518055 , China.
ACS Appl Mater Interfaces. 2019 May 15;11(19):17313-17320. doi: 10.1021/acsami.8b20436. Epub 2019 May 1.
Through in situ transmission electron microscopy (TEM) observation, we report the behaviors of phosphorus (P)-doped silicon nanowires (SiNWs) during electrochemical lithiation/delithiation cycling. Upon lithiation, lithium (Li) insertion causes volume expansion and formation of the crystalline LiSi phase in the P-doped SiNWs. During delithiation, vacancies induced by Li extraction aggregate gradually, leading to the generation of nanopores. The as-formed nanopores can get annihilated with Li reinsertion during the following electrochemical cycle. As demonstrated by our phase-field simulations, such first-time-observed reversible nanopore formation can be attributed to the promoted lithiation/delithiation rate by the P dopant in the SiNWs. Our phase-field simulations further reveal that the delithiation-induced nanoporous structures can be controlled by tuning the electrochemical reaction rate in the SiNWs. The findings of this study shed light on the rational design of high-power performance Si-based anodes.
通过原位透射电子显微镜（TEM）观察，我们报道了磷（P）掺杂硅纳米线（SiNWs）在电化学锂化/脱锂循环过程中的行为。锂化时，锂（Li）的插入会导致体积膨胀，并在P掺杂的SiNWs中形成结晶LiSi相。在脱锂过程中，锂提取诱导的空位逐渐聚集，导致纳米孔的产生。在随后的电化学循环中，新形成的纳米孔会随着锂的重新插入而消失。正如我们的相场模拟所表明的，这种首次观察到的可逆纳米孔形成可归因于SiNWs中P掺杂剂促进的锂化/脱锂速率。我们的相场模拟进一步表明，通过调节SiNWs中的电化学反应速率，可以控制脱锂诱导的纳米多孔结构。本研究的结果为高功率性能硅基负极的合理设计提供了启示。
