Material Design and Optimisation of Electrochemical Li-Ion Storage Properties of Ternary Silicon Oxycarbide/Graphite/Tin Nanocomposites.

Dominik Knozowski,Pradeep Vallachira Warriam Sasikumar,Gurdial Blugan,Maria Gazda,Natalia Kovalska,Piotr Madajski,Monika Wilamowska-Zawłocka

doi:10.3390/nano12030410

Abstract

In this work, we present the characterization and electrochemical performance of various ternary silicon oxycarbide/graphite/tin (SiOC/C/Sn) nanocomposites as anodes for lithium-ion batteries. In binary SiOC/Sn composites, tin nanoparticles may be produced in situ via carbothermal reduction of SnO2 to metallic Sn, which consumes free carbon from the SiOC ceramic phase, thereby limiting the carbon content in the final ceramic nanocomposite. Therefore, to avoid drawbacks with carbon depletion, we used graphite as a substitute during the synthesis of precursors. The ternary composites were synthesized from liquid precursors and flake graphite using the ultrasound-assisted hydrosilylation method and pyrolysis at 1000 °C in an Ar atmosphere. The role of the graphitic component is to ensure good electric conductivity and the softness of the material, which are crucial for long term stability during alloying–dealloying processes. The presented approach allows us to increase the content of the tin precursor from 40 wt.% to 60 wt.% without losing the electrochemical stability of the final material. The charge/discharge capacity (at 372 mA g−1 current rate) of the tailored SiOC/C/Sn composite is about 100 mAh g−1 higher compared with that of the binary SiOC/Sn composite. The ternary composites, however, are more sensitive to high current rates (above 372 mA g−1) compared to the binary one because of the presence of graphitic carbon.

Highlights

Introduction published maps and institutional affilThe exceptional storage capabilities of tin, such as the high gravimetric capacity of 994 mAh g−1 and the relatively low lithiation potential of 0.6 V [1,2,3], make it an appealing anodic material for lithium-ion batteries
We reported a novel silicon oxycarbide–graphite–tin nanoparticle composite for lithium-ion batteries
Final ternary composites were obtained through pyrolysis, which transformed the preceramic polymer into carbon-rich silicon oxycarbide and tin precursor into the tin nanoparticles via carbothermal reduction

Summary

Introduction

The exceptional storage capabilities of tin, such as the high gravimetric capacity of 994 mAh g−1 and the relatively low lithiation potential of 0.6 V [1,2,3], make it an appealing anodic material for lithium-ion batteries. The number one obstacle to overcome is their high-volume expansion of around 260% during the lithium insertion process. This leads to pulverization of electrodes, i.e., material rupture and disintegration upon cyclic volume changes, resulting in poor electrochemical stability over continuous charge/discharge cycles [4]. The matrix has to be able to withstand the strain created upon volume expansion during cycling. Multiple materials have been tested as a potential matrix for Sn nanoparticles (NPs), including metal-based [7,8], carbon-based [9,10], and iations

Methods

Results

Conclusion