Agglomeration and the surface passivating film of Ag nano-brush electrode in lithium batteries

In order to study athe gglomeration phenomena of nano-sized alloy particles as anode material in lithium ion batteries, a silver nano-brush material has been prepared by alumina template and used directly as a working electrode in a Li/Ag nano-brush cell. The morphology variation of the Ag nano-brush electrode during discharge and charge processes has been investigated by scanning electron microscopy (SEM). It is found that a semi-translucent film appears and covers on the surface of each Ag nanowire when the cell discharges to 0.2 V. The film stick separated Ag nanowires together into many bundles. In each bundle, Ag nanowires were merged together. When the voltage of the cell drops to 0.0 V gradually, the aggregation of Ag nanowires becomes more serious. When the cell is recharged to 2.0 V, some Ag wires within a bundle separate from the aggregation and the translucent film still exists on the surface of the separated Ag nanowires and the rest of aggregation. It is supposed that the film is well-known solid electrolyte interphase (SEI). The thickness of the SEI film ranges from 40 nm to several nanometers.