Silicon nanorod formation from powder feedstock through co-condensation in plasma flash evaporation and its feasibility for lithium-ion batteries

Akihiro Tanaka,Kenichi Fukuda,Masashi Dougakiuchi,Ryoshi Ohta,Akira Takeuchi,Makoto Kambara,Toshimi Tanaka

doi:10.1038/s41598-021-01984-y

Akihiro Tanaka, Kenichi Fukuda + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-01984-y

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Abstract

Si nanowires/nanorods are known to enhance the cycle performance of the lithium-ion batteries. However, viable high throughput production of Si nanomaterials has not yet attained as it requires in general expensive gas source and low-rate and multiple-step approach. As one of the potential approaches, in this work, we report the fast-rate Si nanorod synthesis from low-cost powder source by the modified plasma flash evaporation and the fundamental principle of structural formation during gas co-condensation. In this process, while Si vapors are formed in high temperature plasma jet, molten copper droplets are produced separately at the low temperature region as catalysts for growth of silicon nanorods. Si rods with several micrometers long and a few hundred of nanometers in diameter were produced in a single process at rates up to 40 µm s−1. The growth of the Si nanorods from powder source is primarily characterized by the vapor–liquid–solid growth which is accelerated by the heat extraction at the growth point. The battery cells with the Si nanorods as the anode have shown that a higher capacity and better cyclability is achieved for the nanorods with higher aspect ratios.

Highlights

Si nanowires/nanorods are known to enhance the cycle performance of the lithium-ion batteries
SEM images for other conditions are shown in Supplementary Fig. S1
It is noted that Cu and Si nanoparticles are attached to the sides of the rods, which is evidence of continuous supply of Si and Cu during the growth of Si nanorods

Summary

Introduction

Si nanowires/nanorods are known to enhance the cycle performance of the lithium-ion batteries. As one of the potential approaches, in this work, we report the fast-rate Si nanorod synthesis from low-cost powder source by the modified plasma flash evaporation and the fundamental principle of structural formation during gas co-condensation In this process, while Si vapors are formed in high temperature plasma jet, molten copper droplets are produced separately at the low temperature region as catalysts for growth of silicon nanorods. From the materials point of view, silicon is a promising candidate for anode of LiBs owing to its high theoretical capacity, which is 10 times higher than that of the conventional g raphite[1] It experiences a large volume change (up to 400%), associated with the formation of various Li–Si phases during repeated charge/discharge cycles. Si nanowires are to be produced continuously from inexpensive raw materials

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