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ZIF-8-Templated Hollow Cube-like Si/SiO2@C Nanocomposites for Superior Lithium Storage Performance Hao Wang, Hongbin Xu, Kun Jia, and Renbing Wu ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b01553 • Publication Date (Web): 26 Dec 2018 Downloaded from http://pubs.acs.org on January 2, 2019
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ACS Applied Energy Materials
ZIF-8-Templated Hollow Cube-like Si/SiO2@C Nanocomposites for Superior Lithium Storage Performance Hao Wang,† Hongbin Xu,† Kun Jia,† and Renbing Wu*,†,‡ †Department
‡Shanghai
of Materials Science, Fudan University, Shanghai 200433, China
Innovation Institute for Materials, Shanghai 200444, P. R. China.
KEYWORDS: Lithium-ion batteries, Silicon-based anode, Magnesiothermic reduction, Nanocomposites, Metal-organic framework
ABSTRACT: Silicon-based anodes are of particular interests for the application of next generation large-capacity lithium-ion batteries (LIBs) because of their natural abundance and ultrahigh theoretical lithium storage ability. However, the huge volume expansion and inferior cyclic stability severely limit their practical applications. To address this challenge, herein, a hollow cube-like hybrid composites consisting of Si/SiO2 cross-link covered by a carbon layer (Si/SiO2@C) have been rationally synthesized through a facile zeolitic imidazolate frameworks (ZIFs) template method. Within hybrid composites, the porous Si/SiO2 cross-link with internal void can effectively mitigate volume changes and facilitate fast channels for Li+ during charge-
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discharge process while the coated carbon layer can not only improve the electrical conductivity of the composites but also guarantees the structural integrity. As expected, hollow Si/SiO2@C composite electrode performs outstanding electrochemical properties including the excellent reversible capacity (1280 mAh g–1 at 500 mA g–1 after cycled for 200 times) and superior rate performance (782 and 660 mAh g–1 at current densities of 3.2 and 6.4 A g–1, respectively). Considering the convenient preparation and naturally abundant of composites as well as their excellent electrochemical performance, the hollow Si/SiO2@C may hold great promise as advanced electrodes for next-generation LIBs.
INTRODUCTION Important energy storage equipment such as nickel-metal hydride batteries and lithium-ion batteries (LIBs) have been employed in many aspects, such as portable electronics, electric vehicles and grid-scale systems due to their high energy density, long lifespan, low self-discharge rate and good environmental compatibility.1-9 Nevertheless, with the rapidly growing demand for high energy/power density, the performance of these currently commercialized batteries have to be further enhanced. Therefore, developing novel electrode materials with higher energy density has become an urgent task.10-16 Among the available materials for anode of LIBs, silicon (Si) has been considered as a hopeful candidate since it has advantages of the highest theoretical capacity (~ 4200 mAh g–1), rather low discharge potential (~0.4 V vs. Li/Li+) and abundance in nature.17,18 Unfortunately, Si anodes suffer from a drastic volume variation (about 300%) and severe pulverization during cycling, which not only weaken the electrical contact between electrodes and current collectors but also result in the formation of unstable solid electrolyte interphase (SEI) film, and thus rapid capacity
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fading during the cycling process. Additionally, the low intrinsic conductivity of Si also limits its applications.19-24 To track the aforementioned obstacles, nanostructure design and hybridization with various conductive materials such as carbon are considered as effect ways to enhance the electrochemical properties of Si-based anodes.25 In particular, well-defined hybrid nanostructures constructed by nano Si/SiOx (0
