Lithium Trapping in Silicon Nanowire Anodes for Lithium-Ion Batteries

Abstract

Silicon has long been considered a prospective anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity and natural abundance. However, silicon is known to suffer from significant volumetric expansion (~ 400%) during lithiation and de-lithiation. The induced mechanical stress leads to pulverization of silicon as well as electrolyte consumption, which results in poor coulombic efficiency, high irreversible capacity loss and cell failure(1-3). Nanostructured silicon in the form of nanoparticles, nanowires, nanotubes, and nanoporous silicon has demonstrated high capacities, greatly improved coulomb efficiencies, and capacity compared to bulk silicon(4-6). Silicon nanowires (Si NWs) have also shown improved charge transport and capacity retention over nanoparticles. Related to this, silicon-graphite composite anodes featuring 30% Si NWs have demonstrated a capacity of almost 3x graphite(7). However, nanostructured silicon is still prone to capacity fade, primarily caused by the formation of the solid-electrolyte interphase (SEI) and lithium trapping(5, 8-11). Though SEI formation has been widely studied, there has been far less study regarding lithium trapping, despite it contributing to ~30% of the initial capacity loss and accelerating further capacity loss(11, 12). There is a noticeable gap in the literature dedicated to understanding the effect of lithium trapping in Si NWs. In this study, we aim to address this by investigating the effect of lithium trapping in Si NWs anodes for LIBs. Using electrochemical techniques such as constant current (CC), constant current constant voltage (CCCV), electrochemical impedance spectroscopy (EIS), at different rates, we have compared the effects of lithium trapping in Si NWs and the role it plays in determining the end performance of Si NW electrodes. We have also compared the morphological changes induced in Si NWs from lithium trapping. The findings of this study serve to highlight the importance of electrochemical optimisation and form a basis for the future design and testing of LIBs involving Si NWs. REFERENCE LIST D. McNulty, A. Hennessy, M. Li, E. Armstrong and K. M. Ryan, Journal of Power Sources, 545, 231943 (2022).T. Kennedy, E. Mullane, H. Geaney, M. Osiak, C. O’Dwyer and K. M. Ryan, Nano Letters, 14, 716 (2014).T. Kennedy, M. Bezuidenhout, K. Palaniappan, K. Stokes, M. Brandon and K. M. Ryan, ACS Nano, 9, 7456 (2015).M. A. Rahman, G. Song, A. I. Bhatt, Y. C. Wong and C. Wen, Advanced Functional Materials, 26, 647 (2016).X. Zhao and V.-P. Lehto, Nanotechnology, 32, 042002 (2021).T. Kennedy, M. Brandon and K. M. Ryan, Advanced Materials, 28, 5696 (2016).S. Karuppiah, C. Keller, P. Kumar, P.-H. Jouneau, D. Aldakov, J.-B. Ducros, G. Lapertot, P. Chenevier and C. Haon, ACS Nano, 14, 12006 (2020).C. Erk, T. Brezesinski, H. Sommer, R. Schneider and J. Janek, ACS Applied Materials & Interfaces, 5, 7299 (2013).M. N. Obrovac and L. J. Krause, Journal of The Electrochemical Society, 154, A103 (2007).D. Rehnlund, F. Lindgren, S. Böhme, T. Nordh, Y. Zou, J. Pettersson, U. Bexell, M. Boman, K. Edström and L. Nyholm, Energy & Environmental Science, 10, 1350 (2017).T. Kennedy, M. Brandon, F. Laffir and K. M. Ryan, Journal of Power Sources, 359, 601 (2017).B. Zhu, G. Liu, G. Lv, Y. Mu, Y. Zhao, Y. Wang, X. Li, P. Yao, Y. Deng, Y. Cui and J. Zhu, Science Advances, 5, eaax0651 (2019).