Development of novel anodes based on engineered silicon nanocomposites for Li-ion batteries

Student thesis: Master's Thesis

Abstract

Commercially used graphite anodes in Lithium-ion batteries (LIBs) have low theoretical specific capacity of 372mAh g−1 . In this regard, silicon (Si) can be considered as an effective anode material due to its high theoretical specific capacity of 4200 mAh g−1 and a suitable working potential of about ∼0.4 V vs. Li/Li+. However, Si-based anode exhibits a serious problem of capacity decay due to volume expansion during charging cycles (about 400%). In the current work, it is aimed to solve this issue by encapsulating Si nanoparticles by carbon based polydopamine coating. Carbon in different nanostructure forms is incorporated as a conducting material to provide pathway for Li+ ion transport and as buffer for Si volume expansion without breakage during electrochemical cycling. Firstly, various binders and their mixtures were investigated for desirable electrochemical performance of Si/C hybrid composite anode. Following that, Si nanoparticles are engineered using polydopamine as the carbon-based source to form coated Si nanocomposites. The structural and morphological properties of Si/C composites were investigated using comprehensive characterization techniques. The fabricated Si/C composite anode demonstrated a high initial discharge capacity of ~3500 mA h g-1 reflecting its promising nature for LIBs. Electrochemical characterization for electrode performance and material characterization (XRD, SEM) are utilized to study the composition, crystal quality and morphology of the composites.
Date of AwardMay 2022
Original languageAmerican English

Keywords

  • Lithium-ion batteries
  • silicon nanocomposites
  • anodes
  • carbon nanotubes.

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