Brittle to Ductile Transition for Amorphous Silicon Electrodes
Chao Chen (Harvard University), Weili Wang (Harvard University), Efthimios Kaxiras (Harvard University), Zhigang Suo (Harvard University)
Lithium ion batteries: When Chemistry meets Mechanics
Tue 10:45 - 12:15
Salomon 003
Silicon is one of the most promising anode material for lithium-ion batteries, and the mechanical property of amorphous phase of silicon during lithiation is rarely investigated. The “em-ductile” role of lithium in silicon is significant different from other impurities’ embrittle property in ductile material. In the current research, two key factors are taken into consideration: surface energy s and unstable stacking fault energy us, which correspond to energy barriers for fracture and plastic flow correspondingly correspondingly. The ratio of s and us serves as one criteria to justify a material ductile or brittle. The first principle modellings show an abrupt rising of the ratio from 1.2 to 7.8 when x in LixSi reaches 0.5, which indicates the brittle material changes to a ductile material. This approach provides a qualitative prediction for ductile to brittle transition for amorphous material.