title: Thick solid electrolyte interphases grown on silicon nanocone anodes during slow cycling and their negative effects on the performance of Li-ion batteries.
abstract: Thickness, homogeneity and coverage of the surface passivation layer on Si anodes for Li-ion batteries have decisive influences on their cyclic performance and coulombic efficiency, but related information is difficult to obtain, especially during cycling. In this work, a well-defined silicon nanocone (SNC) on silicon wafer sample has been fabricated as a model electrode in lithium ion batteries to investigate the growth of surface species on the SNC electrode during cycling using ex situ scanning electronic microscopy. It is observed that an extra 5 μm thick layer covers the top of the SNCs after 25 cycles at 0.1 C. This top layer has been proven to be a solid electrolyte interphase (SEI) layer by designing a solid lithium battery. It is noticed that the SEI layer is much thinner at a high rate of 1 C. The cyclic performance of the SNCs at 1 C looks much better than that of the same electrode at 0.1 C in the half cell. Our findings clearly demonstrate that the formation of the thick SEI on the naked nanostructured Si anode during low rate cycling is a serious problem for practical applications. An in depth understanding of this problem may provide valuable guidance in designing Si-based anode materials.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Science, Beijing, 100190, China. jjli@iphy.ac.cn hli@iphy.ac.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: Luo
authors.forename: Geng
authors.initials: G
authors.lastname: Chu
authors.forename: Xiaoxiang
authors.initials: X
authors.lastname: Xia
authors.forename: Bonan
authors.initials: B
authors.lastname: Liu
authors.forename: Jieyun
authors.initials: J
authors.lastname: Zheng
authors.forename: Junjie
authors.initials: J
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Changzhi
authors.initials: C
authors.lastname: Gu
authors.forename: Liquan
authors.initials: L
authors.lastname: Chen