Monodisperse Porous Silicon Spheres as Anode Materials for Lithium Ion Batteries

Abstract

Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g−1. In particular, reversible Li storage capacities above 1500 mAh g−1 were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

Silicon and Carbon Nanocomposite Spheres with Enhanced Electrochemical Performance for Full Cell Lithium Ion Batteries

“…The MPSSs show a nearly 20 times enlargement in surface area (Langmuir: 353.22, Brunauer-Emmett-Teller (BET): 214.65 m 2 g −1 ) compare with SSs (Langmuir: 20.07, BET:11.89 m 2 g −1 ) after Mg reduction as suggested by our former study (Fig. 2c)21. It is interesting to note that the Langmuir and BET surface areas of MSNSs are reduced to34.64 m 2 g −1 and 20.94 m 2 g −1 , respectively after CVD carbon coating process which suggests the final product has limited pores.…”

Si@SiOx/Graphene Nanosheets Composite: Ball Milling Synthesis and Enhanced Lithium Storage Performance

“…In recent years, lots of efforts have been put in exploring anode materials with higher specific capacities over graphite. Silicon-based materials have attracted considerable research attentions as one of the most promising anode materials for lithium-ion batteries because of its highest theoretical capacity (4,200 mAh g −1 ) during the formation of Li4.4Si alloys (Netz and Huggins, 2004;Chan et al, 2008;Teki et al, 2009;Winter et al, 2010;Ji et al, 2011;Yue et al, 2013;Wang et al, 2015). However, the huge volume changes during lithiation and de-lithiation process always leads to poor cycle performance and electrical contact, which severely hinders the industrial applications of silicon-based anode materials (Candace et al, 2009;Hertzberg et al, 2010;Bo et al, 2016;Li et al, 2016Li et al, , 2017.…”

Enhanced Electrochemical Performance of Heterogeneous Si/MoSi2 Anodes Prepared by a Magnesiothermic Reduction

“…[19][20] Comparatively, magnesiothermic reduction is the most effective method due to its cost-effective, environmental friendly and facile synthesis process. [21][22][23][24][25] Rice husks have been used as silica sources to produce nanostructured silicon, and silicon nanoparticles have been successfully synthesized from purified beach sands. 23,26 However, during the magnesiothermic reduction process, large amount of heat would be released, leading to the fusion of silicon and occurrence of side reaction, especially the formation of silicon carbide due to the carbon coating.…”