Metal-Organic Frameworks derived novel hierarchical durian-like nickel sulfide (NiS 2 ) as an anode material for high-performance sodium-ion batteries K.J. Zhu a,b,1 , G. Liu a,1 , Y.J. Wang a,⇑ , J. Liu b,⇑ , S.T. Li b , L.Y. Yang b , S.L. Liu b , H. Wang b , T. Xie b a Department of Hepatobiliary Pancreas Surgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China b School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China article info Article history: Received 16 December 2016 Received in revised form 8 March 2017 Accepted 15 March 2017 Available online xxxx Keywords: Nanoparticles NiS 2 Sodium ion batteries Energy storage and conversion abstract An anode material for sodium-ion batteries, Ni-Metal-Organic Frameworks (MOFs)-derived nickel sulfide (NiS 2 ), is first reported. The synthesis strategy involves a novel method in which Ni-based MOFs is fab- ricated as precursor and then sulfured by sublimed sulfur in solid phase reaction. The as synthesized Ni-MOFs-derived NiS 2 shows a hierarchical durian-like nanostructure made of nanoparticles with the diameter of around 10 nm and amorphous carbon with 3 dimensional conductive net skeleton. Moreover, due to the novel hierarchical nanostructure, sodium ions are able to easily insert/extract into/from the active material. As a result, the as synthesized Ni-MOF-derived NiS 2 nanostructure elec- trode exhibits high specific capacity and excellent rate performance. We believe that the hierarchical Ni-MOFs-derived NiS 2 nanoparticles will be one of the most promising electrode materials for sodium- ion batteries. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Recently, with the portable electronic devices and electric vehi- cles being widely used and rapidly developed, studying on the green and efficient energy storage system is considered to be of extremely significant [1]. The high-cost and shortage of the lithium resources are natural bottlenecks limiting the large-scale applica- tion of lithium ion batteries (LIBs) [2,3]. Thus, seeking alternative energy sources is the top priority of researchers. Due to the similar storage mechanism with LIBs, sodium ion batteries (SIBs) have attracted wide attention [4]. Yet, SIBs are not as perfect as expected because the sodium ion radius (1.02 Å) is larger than that of the lithium ion (0.69 Å), making Na + much more difficult to insert/ extract into/from the active materials [5,6]. So there are enormous challenges to develop suitable materials for SIBs in large-scale commercial application. Up to now, researchers have tried countless kinds of active materials in order to obtain excellent electrochemical perfor- mance. The most frequently reported previous materials in SIBs are carbon materials and metal oxide materials owing to their high specific capacities [7,8]. Meanwhile, many researchers study metal sulfides as SIBs anode material, such as FeS 2 , Ni 2 S 3 and MoS 2 [9– 11]. To our best knowledge, there have been few reports on NiS 2 used as SIBs anode material, where Wang et al. adopted the hydrothermal method to synthesize nanostructured nickel disul- fideÀgraphene nanosheets composites [12]. However, this method is not suitable for mass production by many reasons as following: First, the amount of each hydrothermal experiment products is minuscule; Second, the preparation of Graphene oxide is complex and it costs too much. Thus, designing different synthesis methods of electrode material is worth attempting. Herein, we employ a novel method to synthesize Ni-based Metal-Organic Frameworks (MOFs) sulfide. In this work, the syn- thesis method is simple where Ni-based MOFs is fabricated as pre- cursor and then sulfured by sublimed sulfur in solid phase reaction. The carbonaceous matrix can constitute 3 dimensional (3D) conductive net skeleton to improve the mechanical flexibility of the electrochemically active materials, as well as restrain their volume expansion upon cycling, resulting in excellent perfor- mance. The electrochemical measurement results show MOFs- derived NiS 2 has excellent performance on SIBs. Impressively, the as synthesized Ni-MOFs-derived NiS 2 can preserve about 83.8% of the initial discharge specific capacity at 100 mA g À1 after 60 cycles and outstanding rate performance. More importantly, compared with previous work, our method is simple, efficient and low cost, http://dx.doi.org/10.1016/j.matlet.2017.03.087 0167-577X/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. E-mail addresses: wangyjdoctor@163.com (Y.J. Wang), liujun4982004@csu.edu. cn (J. Liu). 1 The first and second authors have equal contribution. Materials Letters xxx (2017) xxx–xxx Contents lists available at ScienceDirect Materials Letters journal homepage: www.elsevier.com/locate/mlblue Please cite this article in press as: K.J. Zhu et al., Metal-Organic Frameworks derived novel hierarchical durian-like nickel sulfide (NiS 2 ) as an anode material for high-performance sodium-ion batteries, Materials Letters (2017), http://dx.doi.org/10.1016/j.matlet.2017.03.087