Research Article Cite This: ACS Appl. Mater. Interfaces 2017, 9, 40386-40393
www.acsami.org
Room-Temperature Solution Synthesis of Mesoporous Silicon for Lithium Ion Battery Anodes Lin Sun,†,‡ Fei Wang,† Tingting Su,† and Hongbin Du*,† †
State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, China ‡ School of Chemistry and Chemical Engineering, Yancheng Institute of Technology, Yancheng, 224051, China S Supporting Information *
ABSTRACT: As an important optoelectronic and energy-storage material, porous silicon (PSi) has attracted great interest in various fields. The preparation of PSi, however, usually suffers from low yields and/or complicated syntheses. Herein, we report a facile solution method to prepare PSi with controllable high specific surface area. Commercial Zintl compound Mg2Si readily reacts with HSiCl3 in the presence of amines at room temperature to produce amorphous PSi in high yields, where in situ formed salt byproducts serve as templates to generate uniform mesopores of ca. 3.8 nm in diameter. After crystallization treatment at 700 °C in flow Ar gas for 40 min, the obtained crystalline PSi coated with carbon layers shows excellent electrochemical performance when served as lithium ion battery anodes. The reversible specific capacity is about 2250 mA h g−1 at 0.1 A g−1 and the capacity retention is maintained at 90% after cycling at high current density of 2 A g−1 for 320 times. This simple, facile preparation method is very promising and paves the way for massive production of porous Si as high-performance anodes in Li-ion battery industry or for other applications, such as drug delivery systems and catalysis. KEYWORDS: porous silicon, lithium ion battery, anode material, solution method, mesoporous structure, synthesis design
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INTRODUCTION
expensive silicon precursors, which limit the practical applications of Si anodes. Porous Si (PSi) with large intrapartilce voids is an attractive alternative to access high-performance LIBs with long cycle lifetimes.18−23 The conventional methods for obtaining PSi usually include chemical/electrochemical etching of bulk Si in HF solution,20,21 chemical vapor deposition of silicon procursors into porous templates,23,24 as well as magnesiothermic reduction of SiO2 precursors.18,19,22,25,26 The former often suffers from corrosive acids and the vast loss of Si materials, while the latter two require high-energy consumption, relatively high-cost well-defined templates and delicate control of reaction conditions. The low yields and complicated syntheses of PSi in these preparations hinder its practical applications as LIB anodes. Recently, F. Dai et al.27 demonstrated a bottom-up synthesis of mesoporous silicon materials with high surface area by reacting NaK alloy with SiCl4. The highly reactive nature of Na−K alloy makes it difficult to produce PSi in a large scale. L. Lin et al.28 produced mesoporous amorphous Si powders by a solvothermal reaction between SiCl4 and Mg in glyme followed by a high-temperature annealing. The obtained porous Si particles exhibited excellent electrochemical performances.
Nanostructured silicon has long drawn great interest in a variety of research areas such as solar cells, biocompatible materials, optoelectronics and sensors in past decades, because of the abundance in nature and unique properties of Si.1−4 Recently, the application of Si as anode materials in the field of lithium ion batteries (LIBs) has been regarded as one of promising alternatives to commercial graphite because of its high theoretical specific capacity (∼4200 mAh g−1, Li22Si5) and low operation potential (
