REVIEW 1702737 (1 of 33) © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.small-journal.com small NANO MICRO Silicon-Based Anodes for Lithium-Ion Batteries: From Fundamentals to Practical Applications Kun Feng, Matthew Li, Wenwen Liu, Ali Ghorbani Kashkooli, Xingcheng Xiao,* Mei Cai, and Zhongwei Chen* K. Feng, M. Li, Dr. W. Liu, A. G. Kashkooli, Prof. Z. Chen Department of Chemical Engineering Waterloo Institute for Nanotechnology Waterloo Institute of Sustainable Energy University of Waterloo 200 University Ave. W, Waterloo, ON N2L 3G1, Canada E-mail: zhwchen@uwaterloo.ca Dr. X. Xiao, Dr. M. Cai General Motors Global Research and Development Center 30500 Mound Road, Warren, MI 48090, USA E-mail: xingcheng.xiao@gm.com The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.201702737. DOI: 10.1002/smll.201702737 1. Introduction 1.1. Energy Situation, and Energy Storage Target Mankind’s high dependence on nonrenewable energy has led to increasing concerns on environment, climate, and human health. Meanwhile, the research and development on clean Silicon has been intensively studied as an anode material for lithium-ion batteries (LIB) because of its exceptionally high specific capacity. However, silicon-based anode materials usually suffer from large volume change during the charge and discharge process, leading to subsequent pulverization of silicon, loss of electric contact, and continuous side reactions. These trans- formations cause poor cycle life and hinder the wide commercialization of silicon for LIBs. The lithiation and delithiation behaviors, and the interphase reaction mechanisms, are progressively studied and understood. Various nanostructured silicon anodes are reported to exhibit both superior specific capacity and cycle life compared to commercial carbon-based anodes. How- ever, some practical issues with nanostructured silicon cannot be ignored, and must be addressed if it is to be widely used in commercial LIBs. This Review outlines major impactful work on silicon-based anodes, and the most recent research directions in this field, specifically, the engineering of silicon architectures, the construction of silicon-based composites, and other performance-enhancement studies including electrolytes and binders. The burgeoning research efforts in the development of practical silicon electrodes, and full-cell silicon-based LIBs are specially stressed, which are key to the successful commercialization of silicon anodes, and large-scale deployment of next-generation high energy density LIBs. Silicon Anodes energy is becoming one of the prime topics of interest around the globe. On the one hand, clean energy from solar and wind has seen growing market size worldwide, leading to a strong demand for highly efficient energy conversion and storage devices for the wide utilization of clean energies. On the other hand, sig- nificant efforts have been devoted to the electrification of vehicles to reduce our reli- ance on petroleum, while correspondingly suitable energy storages devices are still under probe. Lithium-ion batteries (LIBs) have been adopted as the major energy storage technology for portable electronic devices and are also being considered for vastly different markets such as grid scale energy storage. Owing to their environ- mental benignity, relatively high energy density and stable performance, LIBs have found application across multiple indus- tries. In the case of electric vehicles, the market size of LIBs can even surpass that of portable electronics. However, most EVs are not yet competent enough to replace traditional vehicles simply because of impractical driving ranges. The range from a single charge is dependent on the size/energy density of the battery. Increasing the size of the integrated battery not only increases the cost of the EV but also increases the mass of the whole electric vehicle, lowering the range. This depend- ence loop between cost, driving range, battery size, and total vehicle mass introduces an optimization problem and strongly depends on the system design of the EV. EVs with near prac- tical ranges do exist in the market but the high cost from the large battery pack typically renders these too expensive. In this regard, batteries with higher energy and power density, lower cost, and improved safety are in great demand. According to the long-term goal set by the U.S. Advanced Battery Consortium LLC (USABC) to address the issue, energy density of a LIB pack system has to reach 235 Wh kg −1 or 500 Wh L −1 at a discharge rate of 1/3 C (1/3 C discharge rate indicates that a battery can be fully discharged in 3 hours), [1] in addition to the requirement of 15 years’ calendar life and up to 1000 cycles. These require- ments and practical needs in real applications have limited the chemistry selection of current commercially available LIBs to the marginally sufficient graphite versus lithium transition metal oxides cells. Therefore, new electrode materials and Small 2018, 1702737