Browsing by Author "Li, Hejun"

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    Al-based MOF derived self-assembled carbon nanosheets as innovative anodes for Li-and Na-ion batteries
    (IOP, 2019-12-20) Zeng, Xie-Rong; Wenwu, Jin; Li, Hejun; Saikumar, Inguva; Zhang, Qi; Shaozhong, Zeng; Guozhong, Xu; Zou, Jizhao
    Functional modification and structural design of carbon electrode materials are considered as a cost-effective method to improve their electrochemical performance. In this study, a solvothermal method is applied to realize self-assembly of the metal-organic framework. After simple carbonization and acid treatment, carbon nanosheets with 2D adjustable defective sub-units are successfully prepared for the first time. It is found that carbonization temperature has a significant effect on the carbon skeleton structure. The optimal nanostructures with large specific surface area and appropriate pore size distribution make self-assembled carbon nanosheets having excellent Li/Na- ion storage properties. In addition, the adjustable carbon skeleton structure can effectively avoid irreversible damage when charge-discharge cycles. For Li-ion batteries, a specific capacity of 825 mAh g−1 is achieved after 100 cycles at 0.1 C, while for Na-ion batteries a specific capacity of 193 mAh g−1 is observed after 100 cycles at 0.5 C. Moreover, for Na-ion batteries, even at a high rate of 5 C the material delivers a specific capacity of 109.5 mAh g−1 after 3500 cycles.
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    ItemOpen Access
    Facile synthesis of TiN nanocrystals/graphene hybrid to chemically suppress the shuttle effect for lithium-sulfur batteries
    (Elsevier, 2020-01-08) Tu, Jianxin; Li, Hejun; Lan, Tongbin; Zeng, Shao-Zhong; Zou, Jizhao; Zhang, Qi; Zeng, Xierong
    Herein, we present a microwave reduction strategy for the synthesis of reduced-graphene-oxide (rGO) supported TiN nanoparticle hybrid (TiN/rGO) under N2 atmosphere. The method involves GO reduction, metal oxide reduction and nitridation reaction in one single step. Due to TiN high conductivity and good interfacial affinity between it and lithium polysulfides (LiPSs), the prepared TiN/rGO-Sulfur (TiN/rGO-S) cathodes demonstrate rapid charge transfer, lower polarization, faster surface redox reaction kinetic and enhanced stability cycling performance than rGO-Sulfur (rGO-S) and TiO2/rGO-Sulfur (TiO2/rGO-S) cathodes. The initial capacity reaches 1197.6 mA h g−1 with a reversible capacity of 888.7 mA h g−1 being retained after 150 cycles at 0.1 C.