Silicon Nanowire Fabric as a Lithium Ion Battery Electrode Material

Abstract

A nonwoven fabric with paperlike qualities composed of silicon nanowires is reported. The nanowires, made by the supercritical-fluid-liquid-solid process, are crystalline, range in diameter from 10 to 50 nm with an average length of >100 μm, and are coated with a thin chemisorbed polyphenylsilane shell. About 90% of the nanowire fabric volume is void space. Thermal annealing of the nanowire fabric in a reducing environment converts the polyphenylsilane coating to a carbonaceous layer that significantly increases the electrical conductivity of the material. This makes the nanowire fabric useful as a self-supporting, mechanically flexible, high-energy-storage anode material in a lithium ion battery. Anode capacities of more than 800 mA h g(-1) were achieved without the addition of conductive carbon or binder.

A Green and Facile Way to Prepare Granadilla‐Like Silicon‐Based Anode Materials for Li‐Ion Batteries

“…(≈4200 mAh g −1 ), relatively low discharge potential (≈0.5V vs Li/Li + ), abundance, and environmental benignity. [1][2][3][4][5][6] However, the dramatic volume change (>300%) during lithiation and delithiation processes leads to severe pulverization and continual formation of solid electrolyte interphase (SEI) on the newly formed silicon surfaces, resulting in a large capacity loss. [7][8][9][10][11] Therefore, the cycling performance of silicon-based anodes is still far from satisfactory from a commercial point of view.…”

“…[ 12 ] Silicon nanoparticles (Si NPs) have been found to tolerate extreme changes in volume with cycling. [ 13 ] Hence, great efforts have been made to improve the cycling stability and electrical conductivity by using various Si-based nanostructures, including Si nanowires, [ 3,14,15 ] porous Si, [16][17][18][19] and conductive agent coated Si such as carbon, [ 18,20,21 ] Ag, [ 22,23 ] and conducting polymer. [ 24 ] Among them, a yolkshell-structured carbon@void@silicon (CVS) composite [ 25,26 ] is quite promising for practical applications, because the void space between the outer carbon shell and the inside Si NP allows the room for volume changes of Si NP without deforming the carbon shell and SEI fi lm, which in turn allows for the growth of a stable SEI on the surface of the outer carbon shell.…”

Facile synthesis of freestanding Si nanowire arrays by one-step template-free electro-deoxidation of SiO2 in a molten salt

“…The reliance on the substrate of Si NWAs not only limits the variety of preparation, but also hampers the performance in applications. For example, both well-designed Si substrate films 5,6 and freestanding nanostructured Si 7,8 produce better anode performance than Si NWAs in Li-ion batteries because of the features of a lightweight substrate or freestanding structure. The dense substrate could also hinder the mass transfer in the fluid phase when the Si NWAs serve as antibacterial materials or sensors.…”

Recent Progress in Synthesis and Application of Low-Dimensional Silicon Based Anode Material for Lithium Ion Battery

“…The saturation process is controlled by the applied heat and pressure. Due to the participation of supercritical of liquid, the fabricated silicon nanowires are coated with a thin chemisorbed polyphenylsilane shell [51,[97][98][99]. A large yield of detect-free microscale silicon nanowires was obtained with uniform diameter distribution [96].…”