Scalable production of self-supported WS2/CNFs by electrospinning as the anode for high-performance lithium-ion batteries

WS2/carbon nanofibers (WS2/CNFs) are obtained by a simple electrospinning method in which few-/single-layer WS2 is uniformly embedded in carbon fibers. When used as the active anode material for Li-ion cells, these nanofibers exhibit a first-cycle discharge/charge capacity of 941/756 mAh/g at 100 mA/g and maintain a capacity of 458 mAh/g after 100 cycles at 1 A/g. The evolution of size and crystallinity of WS2 with heating treatment are systematically studied, which are found to strongly influence the final electrochemical performance. Interestingly, the WS2 samples of lowest crystallinity show the highest performance among all studied samples, which could result from the large interfacial capacity for Li ions due to their large specific surface area. More interestingly, the inherent flexible attribute of electrospun nanofibers renders them a great potential in the utilization of binder-free anodes. Similar high discharge/charge capacity of 761/604 mAh/g with a first coulombic efficiency of 79.4% has been achieved in these binder-free anodes. Considering the universal of such simple and scalable preparation strategy, it is very likely to extend this method to other similar two-dimensional layered materials besides WS2 and provides a promising candidate electrode for developing flexible battery devices.