Excellent Cyclic and Rate Performances of SiO/C/Graphite Composites as Li-Ion Battery Anode.

Long Hu,Liuzhang Ouyang,Hui Wang,Renheng Tang,Wenming Xia,Tai Sun,Renzong Hu

doi:10.3389/fchem.2020.00388

Long Hu, Liuzhang Ouyang + Show 5 more

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https://doi.org/10.3389/fchem.2020.00388

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Abstract

The SiO-based composites containing different carbon structures were prepared from asphalt and graphite by the milling, spray drying, and pyrolysis. In the obtained near-spherical composite particles, the refined amorphous SiO plates, which are coated with an amorphous carbon layer, are aggregated with the binding of graphite sheets. The SiO/C/Graphite composites present a maximum initial charge capacity of 963 mAh g−1 at 100 mA g−1, excellent cyclic stability (~950 mAh g−1 over 100 cycles), and rate capability with the charge capacity of 670 mAh g−1 at 1,000 mA g−1. This significant improvement of electrochemical performances in comparison with pristine SiO or SiO/C composite is attributed to the unique microstructure, in which both the graphite sheets and amorphous carbon coating could enhance the conductivity of SiO and buffer the volume change of SiO. The higher pyrolysis temperature causes the denser spherical microstructure and better cycle life. Our work demonstrates the potential of this SiO/C/Graphite composite for high capacity anode of LIBs.

Highlights

For the pristine Silicon monoxide (SiO), the broad scattering peak ranging 15–35◦ is assigned to amorphous SiO, and the weak Si (111) diffraction indicates that a small amount of crystalline Si retained in the amorphous SiO
The XRD pattern of SiO/C-700 composite does not show any diffraction peaks, suggesting that the asphalt transformed to amorphous carbon at the pyrolysis temperature of 700◦C
For the SiO/C/G-900 composite, the appearance of Si diffractions implies the partial thermal reduction reaction of SiO with carbon at 900◦C, which could not occur at 700◦C for the SiO/C/G-700 composite

Summary

INTRODUCTION

With the rapid development of portable electronic devices and plug-in hybrid electric vehicles, high-capacity anode materials are urgently essential to satisfy the ever-increasing energy storage density requirements of LIBs (Krywko-Cendrowska et al, 2013; Song et al, 2013; Yamamura et al, 2013; Yu et al, 2014), since the theoretical specific capacity of commercial graphite anode is limited to 372 mAh g−1 (Wu et al, 2014; Li et al, 2015; Wang et al, 2015; Fu et al, 2018). Wang et al (2011) prepared the SiO/C composite by the modified Stöber method, which exhibited a capacity of 800 mAh g−1 after 50 cycles. Yuan et al (2015) prepared the SiO/C composite by a hydrothermal process, which exhibited a capacity of 744 mAh g−1 at 0.1 C after 50 cycles. A spherical composite of amorphous SiO, amorphous carbon, and graphite was obtained by the preparation process of mechanical milling, spray drying, and heat-treatment. The obtained SiO-based composites exhibited excellent cyclic capacity. The SiO/C composite without the addition of graphite was prepared by the same preparing process from SiO and asphalt with the mass ratio of 3:1 at the pyrolysis temperature of 700◦C, the obtained composite was termed as SiO/C-700. The galvanostatic cycling test is carried out with Land CTR 2001A Tester at different current densities in the voltage range of 0.01–1.5 V vs. Li/Li+ to measure the specific capacity, rate capability and Coulombic efficiency

RESULTS AND DISCUSSION

CONCLUSIONS

DATA AVAILABILITY STATEMENT