In-situ nanomechanical characterization of electrochemical cycles in lithium ion batteries

This paper presents a bilayer cantilever for sensitive and quantitative measurements of mechanical stress during electrochemical cycling in lithium ion batteries. The fabricated MEMS cantilever with anode material was tested in a customized liquid cell and its deformation associated with stress during charge/discharge was monitored by a white light interferometer. During lithiation (Li ion insertion), the maximum compressive stress was -0.35GPa at the cell voltage 165mV. During delithiation, the maximum tensile stress was 0.5GPa at 370mV. Both occurred in the first cycle. When the cell voltage was below 100mV during lithiation, major film cracking occurred, which lead to relieving compressive stress. The overall stress showed gradual reduction over the rest of cycles.