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Xu, Jiantie,Shui, Jianglan,Wang, Jianli,Wang, Min,Liu, Hua-Kun,Dou, Shi Xue,Jeon, In-Yup,Seo, Jeong-Min,Baek, Jong-Beom,Dai, Liming American Chemical Society 2014 ACS NANO Vol.8 No.10
<P>Although much progress has been made to develop high-performance lithium–sulfur batteries (LSBs), the reported physical or chemical routes to sulfur cathode materials are often multistep/complex and even involve environmentally hazardous reagents, and hence are infeasible for mass production. Here, we report a simple ball-milling technique to combine both the physical and chemical routes into a one-step process for low-cost, scalable, and eco-friendly production of graphene nanoplatelets (GnPs) edge-functionalized with sulfur (S-GnPs) as highly efficient LSB cathode materials of practical significance. LSBs based on the S-GnP cathode materials, produced by ball-milling 70 wt % sulfur and 30 wt % graphite, delivered a high initial reversible capacity of 1265.3 mAh g<SUP>–1</SUP> at 0.1 C in the voltage range of 1.5–3.0 V with an excellent rate capability, followed by a high reversible capacity of 966.1 mAh g<SUP>–1</SUP> at 2 C with a low capacity decay rate of 0.099% per cycle over 500 cycles, outperformed the current state-of-the-art cathode materials for LSBs. The observed excellent electrochemical performance can be attributed to a 3D “sandwich-like” structure of S-GnPs with an enhanced ionic conductivity and lithium insertion/extraction capacity during the discharge–charge process. Furthermore, a low-cost porous carbon paper pyrolyzed from common filter paper was inserted between the 0.7S-0.3GnP electrode and porous polypropylene film separator to reduce/eliminate the dissolution of physically adsorbed polysulfide into the electrolyte and subsequent cross-deposition on the anode, leading to further improved capacity and cycling stability.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-10/nn5047585/production/images/medium/nn-2014-047585_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5047585'>ACS Electronic Supporting Info</A></P>
Fan, Qinghua,Noh, Hyuk-Jun,Wei, Zengxi,Zhang, Jiakui,Lian, Xin,Ma, Jianmin,Jung, Sun-Min,Jeon, In-Yup,Xu, Jiantie,Baek, Jong-Beom Elsevier 2019 Nano energy Vol.62 No.-
<P><B>Abstract</B></P> <P>Although lithium ion batteries (LIBs) hold great promise as a next generation power supply, the poor rate capability of the graphite that is mainly used as the battery anode limits high-performance LIBs. Compared to other reported carbon-based materials, however, its relatively low average working voltage still makes it attractive. Herein, we were able to introduce carbon disulfide (CS<SUB>2</SUB>) at the edges of graphene nanoplatelets (GnPs) with rich –C=S/-C-S bonds <I>via</I> ball-milling graphite in the presence of CS<SUB>2</SUB>. The resultant edge-thionic acid-functionalized GnPs (TAGnPs) exhibited a larger accessible surface area and smaller particle size than pristine graphite. Importantly, the TAGnPs retained a long-range-ordered layered structure similar to pristine graphite. When the TAGnPs were used as anode materials for LIBs, they displayed superior rate capability (<I>e.g.</I>, high average reversible capacities of 228.3, 208.1, 141.0 and 80.6 mAh g<SUP>−1</SUP> at 0.5, 1, 2 and 5 A g<SUP>−1</SUP>, respectively) compared to pristine graphite and the reference edge-hydrogenated GnPs (HGnPs), which mainly have -C-H bonds at their edges. Theoretical calculations also indicated that the presence of –C=S/-C-S bonds at the edges of TAGnPs enabled stronger Li<SUP>+</SUP> adsorption capability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Edge-thioated graphene nanoplatelets (TAGnPs) prepared by ball-milling graphite in the presence of carbon disulfide (CS<SUB>2</SUB>). </LI> <LI> TAGnPs have long-range-ordered structure similar to graphite. </LI> <LI> The TAGnPs have a larger accessible surface area than graphite. </LI> <LI> TAGnPs exhibit superior rate capability (>0.5 A g<SUP>−1</SUP>). </LI> <LI> TAGnPs reveal high average reversible capacities of 228.3, 208.1, 141.0 and 80.6 mAh g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>