title: High-rate, ultralong cycle-life lithium/sulfur batteries enabled by nitrogen-doped graphene.
abstract: Nitrogen-doped graphene (NG) is a promising conductive matrix material for fabricating high-performance Li/S batteries. Here we report a simple, low-cost, and scalable method to prepare an additive-free nanocomposite cathode in which sulfur nanoparticles are wrapped inside the NG sheets (S@NG). We show that the Li/S@NG can deliver high specific discharge capacities at high rates, that is, ∼ 1167 mAh g(-1) at 0.2 C, ∼ 1058 mAh g(-1) at 0.5 C, ∼ 971 mAh g(-1) at 1 C, ∼ 802 mAh g(-1) at 2 C, and ∼ 606 mAh g(-1) at 5 C. The cells also demonstrate an ultralong cycle life exceeding 2000 cycles and an extremely low capacity-decay rate (0.028% per cycle), which is among the best performance demonstrated so far for Li/S cells. Furthermore, the S@NG cathode can be cycled with an excellent Coulombic efficiency of above 97% after 2000 cycles. With a high active S content (60%) in the total electrode weight, the S@NG cathode could provide a specific energy that is competitive to the state-of-the-art Li-ion cells even after 2000 cycles. The X-ray spectroscopic analysis and ab initio calculation results indicate that the excellent performance can be attributed to the well-restored C-C lattice and the unique lithium polysulfide binding capability of the N functional groups in the NG sheets. The results indicate that the S@NG nanocomposite based Li/S cells have a great potential to replace the current Li-ion batteries.
authors: i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences , Suzhou, Jiangsu 215123, China.
authors: Yongcai
authors: Y
authors: Qiu
authors: Wanfei
authors: W
authors: Li
authors: Wen
authors: W
authors: Zhao
authors: Guizhu
authors: G
authors: Li
authors: Yuan
authors: Y
authors: Hou
authors: Meinan
authors: M
authors: Liu
authors: Lisha
authors: L
authors: Zhou
authors: Fangmin
authors: F
authors: Ye
authors: Hongfei
authors: H
authors: Li
authors: Zhanhua
authors: Z
authors: Wei
authors: Shihe
authors: S
authors: Yang
authors: Wenhui
authors: W
authors: Duan
authors: Yifan
authors: Y
authors: Ye
authors: Jinghua
authors: J
authors: Guo
authors: Yuegang
authors: Y
authors: Zhang