Characteristics and electrochemical performances of silicon/carbon nanofiber/graphene composite films as anode materials for binder-free lithium-ion batteries

Ruye Cong,Hochun Lee,Chang-Seop Lee,Minsang Jo,Ju-Beom Song,Jin-Yeong Choi

doi:10.1038/s41598-020-79205-1

Abstract

We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs). Silicon nanoparticle (Si)/carbon nanofiber (CNF)/reduced graphene oxide (rGO) composite films were prepared by simple physical filtration and an environmentally-friendly thermal reduction treatment. The films were used as high-performance anode materials for self-supporting, binder-free LIBs. Reducing graphene oxide improves the electron conductivity and adjusts to the volume change during repeated charge/discharge processes. CNFs can help maintain the structural stability and prevent the peeling off of silicon nanoparticles from the electrodes. When the fabricated Si/CNF/rGO composites were used as anodes of LIBs, the initial specific capacity was measured to be 1894.54 mAh/g at a current density of 0.1 A/g. After 100 cycles, the reversible specific capacity was maintained at 964.68 mAh/g, and the coulombic efficiency could reach 93.8% at the same current density. The Si/CNF/rGO composite electrode exhibited a higher specific capacity and cycle stability than an Si/rGO composite electrode. The Si/CNF/rGO composite films can effectively accommodate and buffer changes in the volume of silicon nanoparticles, form a stable solid–electrolyte interface, improve the conductivity of the electrode, and provide a fast and efficient channel for electron and ion transport.

Highlights

We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs)
This is significantly different from the previously reported SEM image results of silicon-based materials as anode materials for lithium-ion batteries[49]. These results indicate that the combination of graphene and carbon nanofibers creates a certain flexible space that can accommodate the volume change of silicon particles during repeated lithiation/delithiation processes, and inhibits the cracking of the active material, thereby preventing the electrode from breakage
Through the characterization of the samples, it was confirmed that reduced graphene oxide (rGO) was uniformly encapsulated on the surface of the silicon nanoparticles, and that the carbon nanofibers were wound around the Silicon nanoparticle (Si)/rGO to form a three-dimensional structure of the Si/CNF/rGO composite

Summary

Introduction

We report the interfacial study of a silicon/carbon nanofiber/graphene composite as a potentially high-performance anode for rechargeable lithium-ion batteries (LIBs). Two-dimensional carbon nano-material with excellent electron and ion transport characteristics, high thermal stability, high mechanical flexibility, high lithium storage capacity, and high specific surface a rea[22,23] These properties provide great advantages for improving the reversible capacities of composite materials. Because of the difference in the volume expansion rate between silicon and graphene, the Si nanoparticles are extremely likely to be peeled off from graphene after several charge/discharge cycles, thereby resulting in a decrease in the capacity of LIB and a rapid decline in the electrode life characteristics in several c ycles[26,27,28] To solve this problem, the manufacturing of a composite material with a stable structure is the main research direction at present

Methods

Results

Conclusion