Li(Al_(1-z)Zn_z) alloys as anode materials for rechargeable Li-ion batteries

摘要

The cycling behavior of anode materials based on alloys from the Li(Al_(1-z)Zn_z) continuous solid solution has been studied. The performance of the most promising composition Li(Al_(0.8)Zn_(0.2)) was tested in half-cells against metallic Li with three different electrolytes and in full Li-ion cells against a V_2O_5 cathode. The underlying structure evolution during cycling and the most relevant fatigue mechanisms are elucidated by x-ray diffraction, nuclear magnetic resonance, and x-ray photoelectron spectroscopy, and reveal a loss of mobile Li due to the ongoing formation of solid electrolyte interfaces. An enhanced stability for Li(Al_(1-z)Zn_z) electrodes with z～0.2 results from a peculiar microstructure due to the demixing of Al and Zn in the Li-poor state and their intermixing in the Li-rich state.