Voltage-controlled synthesis of Cu-Li2O@Si core-shell nanorod arrays as high-performance anodes for lithium-ion batteries

We report here the synthesis of Cu-Li2O@Si core-shell nanorod arrays (CNAs) via the lithiation of pre-synthesized CuO@Si CNAs during the first cycle. When the voltage was set in the usual range for an Si anode (about 0.01-2 V), the reaction between CuO and Li was irreversible. Therefore Cu-Li2O@Si CNAs are the actual anode materials of Li-ion batteries after the first lithiation process. They show a high reversible capacity of 2254 mA h g(-1) after 100 cycles and a good cycling performance at 0.2 C. The core-shell structures enhance the conductivity and accommodate the volume change during the lithiation/delithiation process, which may be responsible for the good performance. The synthetic process was integrated into the electrochemical testing process via voltage control and this process may be extended to other core-shell structures as high-performance anodes in Li-ion batteries.