Structural and morphological modifications of a nanosized 62 atom percent Sn-Ni thin film anode during reaction with lithium

Nanosized electrodeposited 62 atom % Sn-Ni alloy was tested to highlight the effects of volume changes on the cycling life of the electrode during lithiation and delithiation. X-ray diffraction showed that the Ni ₃Sn₄ was the main phase of the as-deposited alloy. A unique feature of the 62 atom % Sn-Ni is that it exhibited a capacity recovery upon cycling. When cycled galvanostatically, the Sn₆₂Ni₃₈ offers low capacity fade while reversibly incorporating lithium up to 600 mAh/g. At the first charge LiSn alloy phases are formed. This led to volume expansion of the electrode causing the formation of cracks. At the following cycles the Ni₃Sn₄, phase was restored and preserved over extensive cycling revealing the reversibility of the reaction between Ni ₃Sn₄, and Li⁺. As to the reasons of the capacity recovery noticed with this alloy, scanning electron microscopy images provided evidence of modifications of the surface condition accompanying a volume change during cycling. The chemical diffusion coefficient (D _Li) value determined from electrochemical impedence spectroscopy measurements during lithium insertion was within 10^-9 to 10 ^-10 cm² s^-1.