In this study, graphene-selenium hybrid microballs (G-SeHMs) are prepared in one step by aerosol microdroplet drying using a commercial spray dryer, which represents a simple, scalable continuous process, and the potential of the G-SeHMs thus prepared is investigated for use as cathode material in applications of lithium-selenium secondary batteries. These morphologically unique graphene microballs filled with Se particles exhibited good electrochemical properties, such as high initial specific capacity (642 mA h g-1 at 0.1 C, corresponding to Se electrochemical utilisation as high as 95.1%), good cycling stability (544 mA h g-1 after 100 cycles at 0.1 C; 84.5% retention) and high rate capability (specific capacity of 301 mA h g-1 at 5C). These electrochemical properties are attributed to the fact that the G-SeHM structure acts as a confinement matrix for suppressing the dissolution of polyselenides in the organic electrolyte, as well as an electron conduction path for increasing the transport rate of electrons for electrochemical reactions. Notably, based on the weight of hybrid materials, electrochemical performance is considerably better than that of previously reported Se-based cathode materials, attributed to the high Se loading content (80 wt%) in hybrid materials.
Bibliographical noteFunding Information:
This work was supported by the energy efficiency and resource grant (No: 20122010100140) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) funded by the Ministry of Knowledge Economy, Korean government. This work was also supported by the third stage of Brain Korea 21 Plus Project in 2016 and a grant from the Fundamental RandD program and funded by the Korea Institute of Ceramic Engineering and Technology (KICET) and Ministry of Trade, Industry and Energy (MOTIE), Republic Korea.
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