Flexible free-standing sulfurized polyacrylonitrile electrode for stable Li/Na storage
2019 Elsevier Ltd Flexible lithium sulfur batteries are promising power sources for the next generation wearable electronics, due to their high energy density and low cost. Here, we demonstrate a metal current collector-free, binder-free, flexible sulfurized polyacrylonitrile film electrode with hollow tubular nanofibers (H-SPAN), which is fabricated via coaxial electrospinning and a simple heat treatment. The all-fibrous films H-SPAN not only provides three-dimensional continuous electron and ion transport paths, but also suppresses the shuttle effect, contributing to better redox kinetics, cycling performance, and flexibility. The H-SPAN film electrode delivers a high specific lithium storage capacity of 1250 mAh g−1sulfur or 514.75 mAh g−1electrode at 0.1C with stable cycling over 300 cycles. Additionally, when H-SPAN is applied as a cathode for room temperature Na-S batteries, it also exhibits superb capacity and cycling stability (717 mAh g−1sulfur or 295.2 mAh g−1electrode at 0.1C after 200 cycles). The working mechanism of H-SPAN is well elucidated by ex situ Raman spectroscopy and ex situ X-ray Photoelectron Spectroscopy (XPS). The excellent flexibility of the H-SPAN film electrode lends itself well to potential applications in wearable electronic devices.