One-Step Formation of Silicon-Graphene Composites from Silicon Sludge Waste and Graphene Oxide via Aerosol Process for Lithium Ion Batteries.

Hee Dong Jang,Jiaxing Huang,Hankwon Chang,Hyekyoung Kim,Hansu Kim,Sun Kyung Kim,Bong-Gyoo Cho,Hyundong Yoo

doi:10.1038/srep33688

Abstract

Over 40% of high-purity silicon (Si) is consumed as sludge waste consisting of Si, silicon carbide (SiC) particles and metal impurities from the fragments of cutting wire mixed in ethylene glycol based cutting fluid during Si wafer slicing in semiconductor fabrication. Recovery of Si from the waste Si sludge has been a great concern because Si particles are promising high-capacity anode materials for Li ion batteries. In this study, we report a novel one-step aerosol process that not only extracts Si particles but also generates Si-graphene (GR) composites from the colloidal mixture of waste Si sludge and graphene oxide (GO) at the same time by ultrasonic atomization-assisted spray pyrolysis. This process supports many advantages such as eco-friendly, low-energy, rapid, and simple method for forming Si-GR composite. The morphology of the as-formed Si-GR composites looked like a crumpled paper ball and the average size of the composites varied from 0.6 to 0.8 μm with variation of the process variables. The electrochemical performance was then conducted with the Si-GR composites for Lithium Ion Batteries (LIBs). The Si-GR composites exhibited very high performance as Li ion battery anodes in terms of capacity, cycling stability, and Coulombic efficiency.

Highlights

One of the very promising applications of recovered Si particles for value added materials is as anode materials in lithium ion batteries (LIBs) because Si exhibits the highest theoretical energy density of 3579 mAh/g
The field emission scanning electron microscopy (FE-SEM) analysis indicated that the as-prepared Si-GR composites had a crumpled paper ball-like morphology and the Si particles were completely encapsulated by GR sheets (Fig. 1a, Supplementary materials Figure S1)
A little silicon carbide (SiC) still remained in the extracted particles, the Si particles were effectively extracted by the one-step aerosol process

Summary

Introduction

One of the very promising applications of recovered Si particles for value added materials is as anode materials in lithium ion batteries (LIBs) because Si exhibits the highest theoretical energy density of 3579 mAh/g The GR encapsulated Si fabricated from the extracted Si particles had a high reversible capacity of about 1750 mAh/g with superior capacity retention of the pure Si nanoparticles[10] This process was quite successful, it required two steps in order to extract Si particles from Si sludge waste and synthesize the GR-encapsulated Si composite. We first introduce a novel one-step process which extracts Si particles and generates Si-GR composites from a colloidal mixture of waste Si sludge and graphene oxide (GO) at the same time by ultrasonic atomization-assisted spray pyrolysis This aerosol process supports lower energy consumption, a shorter operating time and an improved recovery rate compared to previous results for forming GR encapsulated Si composites from a colloidal mixture of Si, SiC and GO. The electrochemical performance of the as-prepared Si-GR composites was investigated as anode materials for LIBs in terms of capacity, cycling stability, and Coulombic efficiency

Methods

Results

Conclusion