Investigation of immiscible Sn-Zn coatings with two-layer microstructure as anode material for Li-ion battery

The exfoliation of Sn as a result of volume expansion led to the drastic capacity decay in lithium-ion batteries. In this article, the immiscible Sn-Zn coating was successfully prepared by electrodeposition and applied as the anode material in Li-ion batteries. The physical structure and electrochemical properties were characterized by X-ray diffraction, scanning electron microscope, electron probe microanalysis and charge-discharge test, respectively. The Sn-Zn deposit displayed unique two-layer morphology composed of a Zn flat bottom layer and a Sn dendritic upper layer. The novel Sn-Zn electrodes showed noticeable improvement in cyclability compared to pure Sn film. This improvement was assigned to the characteristic of the two-layer microstructure: the Zn interlayer enhanced the binding strength between Sn dendrites and copper foil; the abundant space among these individual Sn dendrites accommodated the volume expansion during lithiation process. The two-layer Sn-Zn coatings were anticipated as potential anode materials for Li-ion batteries.