Nitrogen-doped hollow porous carbon nanotubes for high-sulfur loading LieS batteries Jiaona Shi a , Qi Kang b , Yan Mi c , Qingquan Xiao a, * a Department of Electronic Science, College of Big Data and Information Engineering, Guizhou University, Guiyang, 550025, China b Department of Polymer Science and Engineering, Shanghai Key Laboratory of Electrical Insulation and Thermal Ageing, Shanghai Jiao Tong University, Shanghai, 200240, China c Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Guangxi University for Nationalities, Nanning, 530006, China article info Article history: Received 11 June 2019 Received in revised form 3 August 2019 Accepted 8 September 2019 Available online 11 September 2019 Keywords: Lithium-sulfur batteries N-doped hollow porous carbon nanotubes (N-HPCNT) Self-supporting High-sulfur loading Long-term cycling abstract Lithium-sulfur (LieS) batteries have attracted extensive attention in the past decades owing to their high theoretical energy density, low-cost and eco-friendliness. However, poorly cycling stability and rapidly decay caused by shuttle effects at high-sulfur loading condition restrain their practical applications. Focusing on these issues, N-doped hollow porous carbon nanotubes (N-HPCNT) as a self-supporting sulfur cathode is developed. The inherent conductivity and abundant pores of 3D continuous frame- work not only allow a high-sulfur content (67 wt%) and block the polysulfides via physical confinement, but also trap the polysulfides by the nitrogen heteroatoms (4.60 wt%) via strong chemisorption. Benefiting from the above-mentioned merits, the self-supporting S/N-HPCNT cathode with 3 mg cm 2 sulfur delivers high reversible capacity, super rate capability (1152 and 852.8mAh g 1 at 0.2 and 3 C, respectively) and long cycling stability (717.9mAh g 1 after 500 cycles at 1 C). Even under a higher sulfur loading (8 mg cm 2 ), it still exhibits a stable areal capacity of 7.72 mAh cm 2 (corresponding to 965.1 mAh g 1 ) after 60 cycles. This work provides a pathway for developing high performance LieS batteries. © 2019 Elsevier Ltd. All rights reserved. 1. Introduction To meet the ever-growing demands for portable electronic de- vices and electrical vehicles, low cost and eco-friendly lithium- sulfur (LieS) batteries as one of promising candidate have attracted considerable attention owing to their high theoretical energy density (2600 Wh Kg 1 )[1e3]. Moreover, LieS batteries also own a high theoretical specific capacity (1675 mA g 1 ), which is one order of magnitude higher than that of traditional lithium-ion batteries (LIBs) [2,4]. However, several critical challenges including the lower electrical conductivity of sulfur and its discharged products (Li 2 S/ Li 2 S 2 ), the low cycling stability induced by dissolution of interme- diate polysulfides (Li 2 S n , 4  n  8), and the large volumetric expansion (~80%) of sulfur during lithiation/delithiation processes also restrict their practical applications [2,5,6]. To overcome these drawbacks, strenuous efforts have been made to optimize the structure and composition of sulfur cathode, and mitigate the “shuttling effect” through the sulfur-host materials over the past decade. Numerous multi-structured sulfur host materials, such as carbon materials, metal oxides/sulfides/nitrides, metal/covalent organic frameworks and polymer composite frameworks have been designed to alleviate the shuttle effect [7e21]. However, most of the reported hosts/sulfur composites possessed low sulfur content (<60 wt%) and low sulfur-loading (1e3 mg cm 2 ) or even lower, which make them fail to meet the requirements for practical application [4,22]. Thus, it is crucial to construct a high-areal ca- pacity LieS battery (>4 mAh cm 2 ) that can be comparable to the state-of-the-art commercial LIBs, and its cathode not only has high sulfur loading (>3 mg cm 2 ) but also has a high content (>60 wt%). Recently, a few carbon-based/sulfur hybrids could reach both a high sulfur content and loading, but are limited by poor rate capability and short cycle life [23e26]. To address above-mentioned issues, many multi-architecture host materials have been developed to reduce the shuttle effect and enhance the electrochemical kinetics of sulfur. Among them, non-polar carbon materials with good conductivity, structures and morphologies diversity, thus are main option to explore the advanced LieS batteries host materials for sulfur-based cathodes * Corresponding author. E-mail address: qqxiao@gzu.edu.cn (Q. Xiao). Contents lists available at ScienceDirect Electrochimica Acta journal homepage: www.elsevier.com/locate/electacta https://doi.org/10.1016/j.electacta.2019.134849 0013-4686/© 2019 Elsevier Ltd. All rights reserved. Electrochimica Acta 324 (2019) 134849