Influence of the ZnO nanoarchitecture on the electrochemical performances of binder-free anodes for Li storage

Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg−1 after 100 cycles at 1 Ag−1. This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specific surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes.