Performance Improvement of Nano-Sized Zinc Oxide Electrode by Embedding in Carbon Matrix for Lithium-Ion Batteries

Two different nano-sized zinc oxide (ZnO) composite electrodes are prepared and their electrode performances are compared, in which conductive carbon is added as either a physical mixture (electrode A ) or a matrix (electrode B ). The ZnO composite electrode prepared according to the commonly used method (electrode A ) swells upon lithiation but does not contract in the forthcoming de-lithiation period. Due to this irrevocable electrode expansion, the electrically conductive network comprising the ZnO and carbon particles is destroyed to give rapid capacity decay. The other electrode that is prepared as a countermeasure for the volume-change problem (electrode B ), however, shows a reversible swelling/contraction behavior to give a stable cycle performance (reversible capacity of 700 mA h g −1 up to 200 cycles) with the electrode integrity being retained. In the latter electrode, the carbon matrix that surrounds the embedded ZnO particles seems to accommodate the volume change of ZnO component with a strong resilient force.