Composites of Piezoelectric Materials and Silicon as Anodes for Lithium‐Ion Batteries

Abstract Group IVA elements (Si, Ge, and Sn) are promising candidates for the anode materials of lithium‐ion batteries (LIBs), owing to their large theoretical specific capacities. However, serious problems of pulverization and capacity degradation resulting from the huge volume changes during charge/discharge operations have hindered their successful applications as anode materials in LIBs. In this work, the diffusion behaviors of Li ions in Si(100) and Si(111) slabs with a piezoelectric field applied perpendicularly to the surfaces were investigated by using density functional theory. The results show that the diffusivity of Li in Si can be significantly enhanced by applying the electric field generated from the piezoelectric material. This finding can explain the recent experimental observations, in which an improved electrochemical performance was obtained by using Si/carbon nanotube/BaTiO3 as the anode of a LIB. A new generation of anode composite materials can be designed based on this idea and the piezoelectric material is used not only to accommodate the volume variation of active materials of Si, but also to enhance the charging rate of the LIBs.