The thermal stability of nano-silicon electrodes before and after lithiation was studied by means of differential scanning calorimetry (DSC). It was found that pristine Si electrodes heated in presence of EC/DEC 1M LiPF 6 electrolyte show exothermic reactions between sodium carboxymethylcellulose (Na CMC binder) and LiPF 6 . The products of thermal decomposition of a lithiated nano-Si electrode with electrolyte at different temperatures were identified using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). SEI layer was found to be responsible for the thermal reactions in the range between 77 and 107 • C. Exothermic events between 107 and 140 • C were caused by partial decomposition of LiPF 6 salt, which products initiated further transformations of SEI layer compounds and esterification of Na CMC. Interaction between nano-Li x Si and EC/DEC 1M LiPF 6 was the reason for the main exothermic peaks at temperatures between 150 and 300 • C. Nano-Li x Si heated with EC/DEC solvent mixture without LiPF 6 resulted in electrolyte decomposition at much lower temperatures (>105 • C). Therefore, the important role of LiPF 6 in the thermal stabilization of nano-Li x Si with electrolyte at temperatures <140 • C was confirmed while LiTFSI salt added to EC/DEC was ineffective in the prevention of the main exothermic reaction starting at 105 • C.
A robust and electrochemically stable 3D nanoheterostructure consisting of Si nanoparticles (NPs), carbon nanotubes (CNTs) and reduced graphene oxide (rGO) is developed as an anode material (Si–CNT/rGO) for lithium‐ion batteries (LIBs). It integrates the benefits from its three building blocks of Si NPs, CNTs, and rGO; Si NPs offer high capacity, CNTs act as a mechanical, electrically conductive support to connect Si NPs, and highly electrically conductive and flexible rGO provides a robust matrix with enough void space to accommodate the volume changes of Si NPs upon lithiation/delithiation and to simultaneously assure good electric contact. The composite material shows a high reversible capacity of 1665 mAh g−1 with good capacity retention of 88.6 % over 500 cycles when cycled at 0.5 C, that is, a 0.02 % capacity decay per cycle. The high‐power capability is demonstrated at 10 C (16.2 A g−1) where 755 mAh g−1 are delivered, thus indicating promising characteristics of this material for high‐performance LIBs.
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