Shen Chengxu, Fu Rusheng, Xia Yonggao, Liu Zhaoping
Advanced Li-ion Battery Engineering Laboratory, Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences Ningbo 315201 P. R. China
University of Science and Technology of China, Nanoscience and Technology Institution Suzhou 215123 P. R. China.
RSC Adv. 2018 Apr 18;8(26):14473-14478. doi: 10.1039/c8ra01917g. eCollection 2018 Apr 17.
Electrochemical prelithiation is a facile, effective and extensively used method to improve the initial coulombic efficiency of SiO. However, much less research attention has been devoted to prelithiation effect on initial several cycles. Here, we introduce a new perspective to evaluate the prelithiation behaviors, which could understand in depth the electrochemical prelithiation behaviors and their effects on the following two cycles. Then X-ray photoelectron spectroscopy was further performed to pinpoint the reaction products. It has been found that the quantity of irreversible LiSiO, LiO and SEI (LiCO and LiF) and reversible Li Si are increasing as the prelithiation time extending. When the prelithiation time extending over 20 min, only alloy reaction of Si has been revealed. The regeneration of SEI discloses at least 7% capacity loss in the first cycle which depends on the prelithiated time. However, the reformation of SEI in the second cycles reveals 3% capacity loss. Because the coulombic efficiencies are independent on prelithiated time in the second cycle which indicates only one discharge/charge cycle is enough to form integrated SEI and adequate irreversible LiSiO and LiO except part of unreactive SiO .
电化学预锂化是一种简便、有效且广泛应用的提高SiO初始库仑效率的方法。然而，对预锂化对最初几个循环的影响的研究关注较少。在此，我们引入了一种新的视角来评估预锂化行为，这能够深入理解电化学预锂化行为及其对随后两个循环的影响。然后进一步进行X射线光电子能谱分析以确定反应产物。研究发现，随着预锂化时间的延长，不可逆的LiSiO、LiO和SEI（LiCO和LiF）以及可逆的Li₂Si的量在增加。当预锂化时间延长超过20分钟时，仅观察到Si的合金反应。SEI的再生在第一个循环中揭示了至少7%的容量损失，这取决于预锂化时间。然而，在第二个循环中SEI的重整揭示了3%的容量损失。因为在第二个循环中库仑效率与预锂化时间无关，这表明仅一个充放电循环就足以形成完整的SEI以及足够量的不可逆LiSiO和LiO，除了部分未反应的SiO₂ 。
