Synergistically Assembled Li 2 S/FWNTs@Reduced Graphene Oxide Nanobundle Forest for Free‐Standing High‐Performance Li 2 S Cathodes

Lithium sulfide (Li 2 S) has attracted increasing attention as a promising cathode because of its compatibility with more practical lithium‐free anode materials and its high specific capacity. However, it is still a challenge to develop Li 2 S cathodes with low electrochemical overpotential, high capacity and reversibility, and good rate performance. This work designs and fabricates a practical Li 2 S cathode composed of Li 2 S/few‐walled carbon nanotubes@reduced graphene oxide nanobundle forest (Li 2 S/FWNTs@rGO NBF). Hierarchical nanostructures are obtained by annealing the Li 2 SO 4 /FWNTs@GO NBF, which is prepared by a facile and scalable solution‐based self‐assembly method. Systematic characterizations reveal that in this unique NBF nanostructure, FWNTs act as axial shafts to direct the structure, Li 2 S serves as the internal active material, and GO sheets provide an external coating to minimize the direct contact of Li 2 S with the electrolyte. When used as a cathode, the Li 2 S/FWNTs@rGO NBF achieve a high capacity of 868 mAh g −1 Li2S at 0.2C after 300 cycles and an outstanding rate performance of 433 mAh g −1 Li2S even at 10C, suggesting that this Li 2 S cathode is a promising candidate for ultrafast charge/discharge applications. The design and synthetic strategies outlined here can be readily applied to the processing of other novel functional materials to obtain a much wider range of applications.