Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 12, Issue 18, Pages 20838-20848Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.0c00679
Keywords
pitch; carbon nanosheets; potassium-ion battery; porous carbons; heteroatomic doping; molten salt method
Funding
- Science and Technology Plan Projects of Hunan Province [2017TP1009]
- special fund for innovative construction province of Hunan [2019RS2058]
- Natural Science Foundation of Hunan Province [2018JJ3042]
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Soft carbon is attracting tremendous attention as a promising anode material for potassium-ion batteries (PIBs) because of its graphitizable structure and adjustable interlayer distance. Herein, nitrogen/sulfur dual-doped porous soft carbon nanosheets (NSC) have been prepared with coal tar pitch as carbon precursors in an appropriate molten salt medium. The molten salt medium and N/S dual-doping are responsible for the formation of nanosheet-like morphology, abundant microporous channels with a high surface area of 436 m(2) g(-1) expanded interlamellar spacing of 0.378 nm, and enormous defect-induced active sites. These structural features are crucial for boosting potassium-ion storage performance, endowing the NSC to deliver a high potassiation storage capacity of 359 mAh at 100 mA g(-1) and 115 mAh g(-1) at 5.0 A and retaining 92.4% capacity retention at 1.0 A g(-1) after 1000 cycles. More importantly, the pre-intercalation of K atom from the molten salts helps improve the initial Coulombic efficiency to 50%, which outperforms those of the recently reported carbon anode materials with large surface areas. The density functional theory calculations further illuminate that the N/S dual-doping can facilitate the adsorption of K-ion in carbon materials and decrease the ion diffusion energy barrier during the solid-state charge migration.
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