Post-annealing effects on the electrochemical performance of a Si/TiSi2 heteronanostructured anode material prepared by mechanical alloying

초록

A change in the microstructure of Ti-Si alloys synthesized by high-energy mechanical milling through post-annealing significantly enhances their electrochemical performances as anode materials for lithium-ion batteries (LIBs). The microstructures of ball-milled and post-annealed powders are investigated using high-resolution transmission electron microscopy (HR-TEM). The Si phase is uniformly distributed on the silicide (TiSi2) matrix. The individual Si domains of the mechanical alloying (MA) sample consist of amorphous and crystalline regions with a diffuse interface between the two phases. When MA powder is annealed at 600 degrees C, the Si phase has a well-developed nanocrystalline microstructure: a multi-grain structure with random orientation of nanometric crystal domains. Annealing at 600 degrees C causes a significant improvement in electrochemical performance parameters like cycling stability and rate capability. However, when annealed at 800 degrees C, the electrochemical performances deteriorate due to an increase in the size of Si domains. (C) 2017 Elsevier B.V. All rights reserved.

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