Cu‐Si Nanocable Arrays as High‐Rate Anode Materials for Lithium‐Ion Batteries

There is a surge in developing rechargeable lithium-ion batteries (LIBs) with higher energy densities and higher rate performance for application in powering future advanced communications equipment and electric vehicles (EVs). [ 1–6 ] The development of the electrode materials is essential for the improvement of the electrochemical properties of LIBs. [ 7–10 ] Among various anode materials tested for LIBs, Si has triggered signifi cant research effort because of its low Li-uptake potential and the high theoretical capacity (4200 mA h g − 1 ). [ 6 , 11–19 ] However, the main disadvantage that restricts the application of Si is the large volume changes of Si during Li + insertion and extraction, which results in a pulverization of the Si particles, a peeling off the current connection network, and, consequently, a rapid capacity decline upon cycling. [ 11–17 ] To overcome this issue, Si nanostructures, such as Si nanowires and nanotubes, have been fabricated. [ 6 , 11 , 18–23 ] The procedures for the fabrication of the Si nanostructures have also been well developed. [ 24–26 ] These nanostructures can provide spaces to accommodate the large volume variation during charge and discharge processes and thus allow for facile strain relaxation, which prevents pulverization upon lithium insertion. [ 11–19 , 27 ] The cycle stability of the Si anode has been signifi cantly improved by using these nanostructures. [ 11–17 , 27 ] Nevertheless, the rate capability of these materials highly needed for EVs is still not satisfying. This is possibly due to the lack of favorable electronic conductivity and the continuous growth of the unstable solid electrolyte interphase (SEI) at the Si/electrolyte interface upon cycling. Therefore, a new design for the structure of the Si anode is in high demand to achieve both longer cycling life and higher rate capability. Our previous work suggested that the application of nanocable structures in LIBs electrodes can signifi cantly improve the batteries’ electrochemical performance, especially the high