Journal
SMALL
Volume 18, Issue 12, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/smll.202107113
Keywords
anodes; hard carbons; micro; mesopores; potassium migration behavior; potassium ion batteries
Categories
Funding
- National Natural Science Foundation of China [22008053, 52002111]
- Key Research and Development Program of Hebei Province [20310601D, 205A4401D]
- Natural Science Foundation of Hebei Province [B2021208061]
- High Level Talents Funding of Hebei Province [A202005006]
- Science Foundation of University of Hebei Province [BJ2020026, BJ2021001]
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Pore-structure design is an effective strategy to improve the K-storage performance in hard carbon. This study explores the relationship between porous structure and K+ migration behavior by synthesizing chemically activated hard carbon spheres with controllable micro/mesopores. The results reveal that micro/mesopores in the hard carbon facilitate adsorption and intercalation of K+ ions, leading to excellent reversible capacity and rate capability.
Pore-structure design with increased ion-diffusion ability is usually regarded as an effective strategy to improve K-storage performance in hard carbon (HC). However, the relationship between porous structure and K+ migration behavior remains unclear and requires further exploration. Herein, a series of chemically activated hard carbon spheres (denoted as AHCSs) with controllable micro/mesopores structure are successfully synthesized to explore intercorrelation between micro/mesopores and K migration behavior. The experimental results indicate AHCSs have two different K+ storage ways, that is, adsorption behavior at high potential region and intercalation process at low potential region. These behaviors are closely related to the pores structure evolution: the micropores afford extra active sites for efficient K-ions adsorption, and therefore positive correlation between micropores and adsorption-contributed capacity is confirmed; the mesopores permit more K-ions intercalation/deintercalation by offering adequate pathways, and as a result positive correlations between mesopores and intercalation-contributed capacity as well as initial Coulombic efficiency are revealed. All these together contribute to achieving excellent reversible capacity, and exceptional rate capability with an ultra-long cycle lifespan in PIBs, and simultaneously exhibit a high energy density as well as considerable cycling stability for potassium-ion full cells. These results promote a fundamental understanding of K+ migration behaviors in hard carbon.
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