Browsing by Author "Haipeng, Li"
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Item Metadata only Enhanced cycle performance of Li/S battery with the reduced graphene oxide/activated carbon functional interlayer(Journal of Energy Chemistry, 2017-11-01) Li, Haipeng; Sun, Liancheng; Zhang, Yongguang; Tan, Taizhe; Wang, Gongkai; Bakenov, Zhumabay; Haipeng, LiAbstract The high-energy lithium/sulfur (Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 mAh/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional (3D) reduced graphene oxide/activated carbon (RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 mAh/g and a reversible capacity of 655 mAh/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.Item Metadata only In situ sol-gel synthesis of ultrafine ZnO nanocrystals anchored on graphene as anode material for lithium-ion batteries(Ceramics International, 2016-08-01) Li, Haipeng; Wei, Yaqiong; Zhang, Yongguang; Zhang, Chengwei; Wang, Gongkai; Zhao, Yan; Yin, Fuxing; Bakenov, Zhumabay; Haipeng, LiAbstract Ultrafine ZnO nanocrystals anchored on graphene were synthesized by a facile and highly efficient in situ sol-gel method. Uniform ZnO nanocrystals with an average size of 9.3nm were well dispersed on graphene nanosheets forming two-dimensional nanostructured ZnO/Graphene hybrids. Due to the intimate integration and strong synergistic effects between the ZnO nanocrystals and graphene nanosheets these hybrids exhibited a stable electrochemical performance. Along with this the graphene anchoring provides to the system high conductivity and large surface area and buffers the ZnO volume change during cycling. Furthermore, ultrafine ZnO nanocrystals provide a short diffusion path for Li+ upon insertion/deinsertion. These structure and property advantages allow the as-prepared ZnO/graphene composite to exhibit a high reversible operation as an anode for lithium batteries with a stable specific discharge capacity of 516mAhg−1 after 100 cycles at a current density of 200mAg−1 and a good rate capability with a discharge capacity of 304mAhg−1 even at a cycling rate of 1500mAg−1.