Si Nanocrystal-Embedded SiOx nanofoils: Two-Dimensional Nanotechnology-Enabled High Performance Li Storage Materials

Hyundong Yoo,Hansu Kim,Shi Xue Dou,Dong Jae Chung,Yong Nam Jo,Jung Ho Kim,Eunjun Park,Min-Sik Park,Jaewoo Lee,Young-Jun Kim,Juhye Bae

doi:10.1038/s41598-018-25159-4

Abstract

Silicon (Si) based materials are highly desirable to replace currently used graphite anode for lithium ion batteries. Nevertheless, its usage is still a big challenge due to poor battery performance and scale-up issue. In addition, two-dimensional (2D) architectures, which remain unresolved so far, would give them more interesting and unexpected properties. Herein, we report a facile, cost-effective, and scalable approach to synthesize Si nanocrystals embedded 2D SiOx nanofoils for next-generation lithium ion batteries through a solution-evaporation-induced interfacial sol-gel reaction of hydrogen silsesquioxane (HSiO1.5, HSQ). The unique nature of the thus-prepared centimeter scale 2D nanofoil with a large surface area enables ultrafast Li+ insertion and extraction, with a reversible capacity of more than 650 mAh g−1, even at a high current density of 50 C (50 A g−1). Moreover, the 2D nanostructured Si/SiOx nanofoils show excellent cycling performance up to 200 cycles and maintain their initial dimensional stability. This superior performance stems from the peculiar nanoarchitecture of 2D Si/SiOx nanofoils, which provides short diffusion paths for lithium ions and abundant free space to effectively accommodate the huge volume changes of Si during cycling.

Highlights

Despite these outstanding advantages of 2D morphology, the synthesis of 2D nanostructured materials has been very limited and applied to only a few materials via chemical vapor deposition (CVD) or self-assembly[21,22,23,24,25,26,27,28,29,30]
We expect that unique 2D Si/SiOx nanofoils can effectively minimize the inevitable mechanical strain induced by Li+ insertion, thereby promoting strong enhancement in Li+ storage capability
The process was deliberately designed after careful consideration of various synthetic parameters, such as the vapor pressure of precursor and the reaction temperature

Summary

Introduction

Despite these outstanding advantages of 2D morphology, the synthesis of 2D nanostructured materials has been very limited and applied to only a few materials via chemical vapor deposition (CVD) or self-assembly[21,22,23,24,25,26,27,28,29,30]. We have developed a highly reliable Si/SiOx nanocomposite via a sol-gel reaction, which exhibited a high reversible capacity In a continuing effort to exploit advanced Si/SiOx nanocomposite using this synthetic approach, we here propose a facile and scalable synthesis of large-area Si/SiOx 2D nanofoils with a thickness of about 8 nm as a potential Li+ storage material for lithium ion batteries (LIBs) via a solution evaporation induced interfacial sol-gel reaction. We expect that unique 2D Si/SiOx nanofoils can effectively minimize the inevitable mechanical strain induced by Li+ insertion, thereby promoting strong enhancement in Li+ storage capability. Our newly developed approach presented here allows the synthesis of facile, cost-effective, and scalable 2D Si/SiOx nanofoils in an aqueous solution by promoting lateral growth of hydrogen silsesquioxane (HSiO1.5, HSQ) nanofoils at the interface between water and air

Methods

Results

Conclusion