The lithiation mechanism of ultrathin 2D ZnO systems working as anode materials for lithium-ion batteries: From Wurtzite to graphene-like structures

Several ZnO nanostructures such as nanosheets, nanotubes and quantum dots with Wurtzite structure have been prepared and studied as lithium-ion anode materials revealing that the increasing interface is a key aspect to improve their performance. To the best of our knowledge, up to now, there are no reports in the literature that deal directly with lithium-ion transport and charge transfer on ultrathin 2D ZnO exhibiting graphene-like and Wurtzite structures working as anode materials for lithium-ion batteries. Here, we present a DFT study on the lithiation of ultrathin 2D ZnO nanostructures including graphene-like (monolayer and bilayer) and Wurtzite (trilayer) structures. We focus on the ionic-electronic transport properties addressing the ionic transport through the different surfaces as well as charge transfer, equilibrium voltages, and work function variations due to lithiation for all systems. We reveal interesting features regarding how deep the reduction of Zn ions is still observed allowing more efficient charge transfer for graphene-like and Wurtzite systems working as anode material for a lithium-ion battery.