Foldable uniform GeOx/ZnO/C composite nanofibers as a high-capacity anode material for flexible lithium ion batteries

Abstract Although certain advantages of high-capacity Ge-based anode materials make them well suited for use in high-performance flexible Li-ion batteries, the lithiation/delithiation–induced volume changes and poor flexibility of these materials limit their application scope. To address this challenge, we herein employ a combination of electrospinning and carbonization to prepare a highly foldable GeOx/ZnO/C (FGCZ) nanofiber composite featuring GeOx and ZnO ultra-uniformly dispersed in mesoporous carbon nanofibers. Specially, we employed carbon nanotubes in the carbon nanofibers to improve the electric conductivity. The abovementioned architecture not only effectively suppresses the volume expansion of GeOx, but also accelerates electron and ion transport, and the as-prepared FGCZ therefore exhibits good cycling performance as a self-supported anode for half-cells, maintaining a discharge capacity of 464 mAh g−1 at a current density of 1 A g−1 after 500 cycles. More importantly, the FGCZ membrane shows excellent foldability and elastic resilience, as exemplified by the fact that a binder-free foldable full cell comprising a commercial flexible LiCoO2/carbon nanotube cathode and an FGCZ anode was able to light a light-emitting diode (i) when folded twice and (ii) during the process of dynamic folding. Thus, our work paves the way to the facile fabrication of foldable materials for use in high-energy flexible devices.