Ball-milling synthesis of ZnO@sulphur/carbon nanotubes and Ni (OH)(2)@sulphur/carbon nanotubes composites for high-performance lithium-sulphur batteries

摘要

Zinc oxide wrapped sulphur/carbon nanotubes (ZnO@S/CNT) and nickel hydroxide wrapped sulphur/ carbon nanotubes (Ni(OH)(2)@S/CNT) nanocomposites are prepared using a simple, low cost and scalable ball-milling method. As the cathodes in Li-S batteries, the as-prepared ZnO@S/CNT composite illustrates a superior high initial capacity of 1663 mAh g(-1) at a charge/discharge rate of 160 mA g(-1), and maintains a reversible capacity at approximately 942 mAh g(-1) after 70 cycles. While for Ni(OH)(2)@S/CNT composites, its initial capacity is also as high as 1331 mAh g(-1), but a poorer cycling stability is presented. When the charge/discharge current is increased to 1600 mA g(-1), a high reversible capacity of 698 mAh g(-1) after 200 cycles still can be obtained for the ZnO@S/CNT composite, far better than that of Ni(OH)(2)@S/CNT composites. The better cycling performance and high discharge capacity can be attributed to the strong interactions between ZnO and S-x(2) species, which is verified by the density functional theory (DFT) calculation result that the ZnO exhibits a higher adsorption energy for Li2S8 than the Ni(OH)(2). (C) 2016 Elsevier Ltd. All rights reserved.