1. KOH-activated hollow carbon spheres with surface functionalization for high-capacity and long-cycle-life lithium-selenium batteries.
- Author
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Zhang, Guohao, Wu, Guangping, Li, Junyi, Wang, Yamei, Xu, Shilong, Niu, Xiaobin, Wu, Rui, Jiang, Jinxia, John Blackwood, Daniel, and Song Chen, Jun
- Subjects
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CHEMICAL processes , *CHEMICAL affinity , *HYDROXYL group , *ACTIVATION (Chemistry) , *LITHIUM-ion batteries , *ELECTRIC batteries - Abstract
[Display omitted] • A method has been proposed to functionalize the surface of carbon hollow nanospheres through KOH chemical activation process to serve as the Se host for lithium-selenium battery. • The assembled battery achieved a high initial discharge specific capacity of 594 mA h g−1 at a current density of 0.5C. • DFT calculations indicated that surface functional groups exhibited strong chemical affinity towards polymeric selenides. • The ex-situ SEM/EIS tests demonstrated excellent reversibility of the electrode. Lithium-selenium (Li-Se) batteries are considered promising alternatives to lithium-ion batteries due to their higher volumetric capacity and energy density. However, they still face limitations in efficiently utilizing the active selenium. Here, we develop surface-functionalized mesoporous hollow carbon nanospheres as the selenium host. By using KOH activation, the surface of the carbon nanospheres is functionalized with hydroxyl groups, which greatly improve the utilization of selenium and facilitate the conversion of lithium selenides, leading to much higher capacities compared to ZnCl 2 activation and untreated carbon nanospheres. Theory and experimental evidence suggest that surface hydroxyl groups can enhance the reduction conversion of polyselenides to selenides and facilitate the oxidation reaction of selenides to elemental selenium. In-situ and ex-situ characterization techniques provided additional confirmation of the hydroxyl groups electrochemical durability in catalyzing selenium conversion. The meticulously engineered Se cathode demonstrates a high specific capacity of 594 mA h g−1 at 0.5C, excellent rate capability of 464 mA h g−1 at 2C, and a stable cycling performance of 500 cycles at 2C with a capacity retention of 84.8 %, corresponding to an ultra-low-capacity decay rate of 0.0144 % per cycle, surpassing many reported lithium-selenium battery technologies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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