FULL PAPER © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 wileyonlinelibrary.com 1. Introduction Lithium-sulfur (Li-S) batteries with high theoretical specific energy (≈2600 Wh kg -1 ) provide new opportunities for next gen- eration rechargeable batteries to satisfy the rapid growth of port- able electronic devices. [1–5] Using sulfur as the cathode material can theoretically deliver a high specific capacity, 1675 mAh g -1 , High Sulfur Loading in Hierarchical Porous Carbon Rods Constructed by Vertically Oriented Porous Graphene-Like Nanosheets for Li-S Batteries Zongmin Zheng, Hongchen Guo, Fei Pei, Xin Zhang, Xinyi Chen, Xiaoliang Fang,* Taihong Wang, and Nanfeng Zheng* The utilization of porous carbon frameworks as hosts for sulfur loading is an important theme in current Li-S battery research. Unfortunately, the high loading of insulating sulfur often leads to low specific capacities, poor rate properties, and rapid capacity loss. To address this challenge, a facile tem- plating route to fabricate a novel host material, hierarchical porous carbon rods constructed by vertically oriented porous graphene-like nanosheets (HPCR) is presented. With a high specific surface area, ultralarge pore volume, hierarchical porous structures, and ideal ion transfer pathways, HPCR is a promising candidate for high sulfur loading. When used as the active material for a sulfur cathode, the HPCR-S composite with 78.9 wt% sulfur exhibits excellent rate performance (646 mAh g -1 sulfur at 5 C) and cycling stability (700 mAh g -1 sulfur after 300 cycles at 1 C). Even with a sulfur content of 88.8 wt%, the HPCR-S composite, without any additional protec- tive polymer coating, still delivers a good rate performance (545 mAh g -1 sulfur at 3 C) and cycling stability (632 mAh g -1 sulfur after 200 cycles at 1 C). More importantly, the high sulfur loading (88.8 wt%) ensures that the HPCR-S com- posite has a high energy density (880 mAh cm -3 cathode after 200 cycles at 1 C). DOI: 10.1002/adfm.201601897 Z. M. Zheng, H. C. Guo, F. Pei, Dr. X. Y. Chen, Dr. X. L. Fang, Prof. T. H. Wang Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen University Xiamen, Fujian 361005, China E-mail: x.l.fang@xmu.edu.cn X. Zhang, Prof. N. F. Zheng State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials and Engineering Research Center for Nano-Preparation Technology of Fujian Province College of Chemistry and Chemical Engineering Xiamen University Xiamen, Fujian 361005, China E-mail: nfzheng@xmu.edu.cn more than five times higher than that of the commercially available insertion com- pound cathodes. [6] More importantly, sulfur is a low cost, environmentally friendly, and abundant resource in nature. However, the practical application of Li-S batteries is still suffering from several problems of the sulfur cathode, including the low conduc- tivity of sulfur, the large volumetric change of sulfur during lithiation/delithiation pro- cess, and the capacity loss induced by the dissolution of intermediate products (Li 2 S n , 4 ≤ n ≤ 8) in the electrolyte. [7–9] To overcome these challenges, efforts have focused on optimizing the composition and structure of the sulfur cathode. Numerous sulfur hosts, such as porous carbon, [10–15] conduc- tive polymer matrix, [16–19] metal oxides/ hydroxides, [20–23] sulfides, [24] and metal organic frameworks, [25] have been recently adopted to improve the utilization of sulfur and reduce the loss of soluble polysulfide species. Unfortunately, in most of the reported results, the overall sulfur content in the cathodes is less than 60 wt%, which is difficult to compete with the commercial insertion compound cathodes. With light weight, good electrical properties, and struc- tural diversity, carbon materials are considered to be the most promising hosts for sulfur loading. [26] The structures of carbon hosts are usually designed according to the following principles: (1) high specific surface area (SSA) to enhance the interaction between the carbon and polysulfides; (2) an inter- connected architecture for sulfur impregnation to improve sulfur utilization; (3) an open framework for fast ion/electron transport; and (4) enough space to accommodate the volu- metric expansion of sulfur. After fulfilling these requirements, a sulfur cathode with a high specific capacity and good sta- bility was not difficult to achieve as long as the sulfur content of the carbon-sulfur composite was kept below 70 wt%. [10–15] Since the carbon-sulfur composites usually need to be mixed with conductive agent and binder, the overall sulfur content in these cathodes are usually below 60 wt%. [10–15] To achieve high sulfur content, several highly porous carbon structures have been recently employed. [27–31] However, the high loading of insulating sulfur inevitably leads to low specific capaci- ties, poor rate properties, and rapid capacity loss. Therefore, Adv. Funct. Mater. 2016, DOI: 10.1002/adfm.201601897 www.afm-journal.de www.MaterialsViews.com