Nano-Si/C Composite Via Carbothermal Shock for Lithium Ion Battery Anode

Abstract

Nowadays, Li-ion batteries are ubiquitous and dominate the portable storage market. However, their utilizations for high-energy applications are limited and they present huge social challenges for the future, especially for the applications to electric and hybrid electric vehicles (EVs and HEVs respectively). One strategy, praised by both academics and industry, the high capacity electrode materials, notably silicon, as it is considered an attractive graphite substitute in Li-ion battery anode. Silicon (Si) is recognized as a representative anode material for next-generation lithium-ion batteries due to properties, such as a high theoretical capacity, suitable working voltage, and high natural abundance. However, inherently, a large volume expansion (~ 400%) during lithiation/delithiation introduces poor electrical conductivity and unstable solid electrolyte interfaces (SEI) films, the Si-based anodes possess serious stability problems hindering practical applications. To overcome the issue, Si-nanoparticles(Si-NPs) has been proposed as a promising solution to overcome the volume expansion and the flowing fracturing problems of the micron-size particles. Thus, various nanoparticles and nano-objects (0D, 1D, 2D and 3D) have been tried for the Li battery anode in the last decade.1, 2 It has been demonstrated that Si-NPs smaller than 150 nm can be avoided the further fracturing upon the repeating lithiation.We propose a technology for preparations of novel Si-NPs/carbon(Si/C) composites on the basis of thermal shock of the carbon materials such as natural and artificial graphites. We developed a facile, one-step carbothermal shock method for transformations from micro-Si to Si-NPs less than 150 nm size and well dispersed on carbon matrix (Figure 1.). The particle size distribution of the Si-NPs was narrow and the dispersion was uniform. The Si/C composite anode exhibited a high specific capacity (>1,000 mAh/g) and predominant fast charging behavior. Reference [1] R. Chen, T. Zhao, X. Zhang, L. Li and F. Wu, Advanced cathode materials for lithium-ion batteries using nanoarchitectonics, Nanoscale Horiz., 2016, 1, 423-444[2] D. Ma, Z. Cao and A. Hu, Si-Based Anode Materials for Li-Ion Batteries: A Mini Review, Nanomicro Lett., 2014, 6(4), 347-358Figure 1. SEM images of Si-NPs/carbon (Si/C) composites Figure 1