Void-shell silicon/carbon/SiCN nanostructures: toward stable silicon-based electrodes
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We present a systematic work to design a void-shell nanostructures for improving the stability of silicon electrodes while alloying with lithium. To enhance the electrical conductivity, silicon is coated with carbon by using a simple and non-hazard route prior to embedding the Si particles in silicon carbonitride (SiCN). An inactive matrix, namely a polymer-derived SiCN ceramic is used to stabilize the composite. Additionally, cavities around silicon to accommodate volume changes are introduced by partial carbon burning. Significant increase in porosity of more than one order of magnitude is found by means of BET measurements for the samples obtained after additional heat treatment in air. TGA coupled with FTIR spectrometry shows that the ceramic matrix is stable upon heating, while burned carbon originates from pyrolyzed fructose. TEM micrographs confirm the presence of carbon/void around silicon particles embedded in the ceramic matrix. Electrochemical investigations reveal an improved conductivity due to the presence of carbon coating. Contribution of silicon in lithium storage is identified, whereas voids introduced around the silicon particles are found to improve cycling stability of silicon.
KeywordsMoS2 Carbon Coating Cycling Stability Silicon Particle Ceramic Matrix
We gratefully acknowledge the financial support of the German Research Foundation (DFG) SPP1473/JP8. We thank Christina Schitco for fruitful discussions and attentive manuscript proof reading. Furthermore, we also thank Ulrike Kunz, Claudia Fasel, and Cristina Schitco for their help with material characterization.
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