Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbona...Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbonaceous electrodes present sluggish kinetics, resulting in unsatisfactory cycling stability and poor rate capability. Herein, we demonstrate that the synergistic effects of the enlarged interlayer spacing and enhanced capacitive behavior induced by the co-doping of nitrogen and sulfur atoms into a carbon structure(NSC) can improve its potassium storage capability. Based on the capacitive contribution calculations, electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique, and density functional theory results, the NSC electrode is found to exhibit favorable electronic conductivity,enhanced capacitive adsorption behavior, and fast K+ ion diffusion kinetics. Additionally, a series of exsitu characterizations demonstrate that NSC exhibits superior structural stability during the(de)potassiation process. As a result, NSC displays a high reversible capacity of 302.8 mAh g-1 at 0.1 Ag-1 and a stable capacity of 105.2 m Ahg-1 even at 2 Ag-1 after 600 cycles. This work may offer new insight into the effects of the heteroatom doping of carbon materials on their potassium storage properties and facilitate their application in PIBs.展开更多
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microsc...We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.展开更多
基金supported by the National Natural Science Foundation of China (51932011, 51972346, 51802356, and 51872334)Innovation-Driven Project of Central South University (2020CX024)the Fundamental Research Funds for the Central Universities of Central South University (2020zzts075)。
文摘Potassium-ion batteries(PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K+/K and Li+/Li. Unfortunately, PIBs with carbonaceous electrodes present sluggish kinetics, resulting in unsatisfactory cycling stability and poor rate capability. Herein, we demonstrate that the synergistic effects of the enlarged interlayer spacing and enhanced capacitive behavior induced by the co-doping of nitrogen and sulfur atoms into a carbon structure(NSC) can improve its potassium storage capability. Based on the capacitive contribution calculations, electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique, and density functional theory results, the NSC electrode is found to exhibit favorable electronic conductivity,enhanced capacitive adsorption behavior, and fast K+ ion diffusion kinetics. Additionally, a series of exsitu characterizations demonstrate that NSC exhibits superior structural stability during the(de)potassiation process. As a result, NSC displays a high reversible capacity of 302.8 mAh g-1 at 0.1 Ag-1 and a stable capacity of 105.2 m Ahg-1 even at 2 Ag-1 after 600 cycles. This work may offer new insight into the effects of the heteroatom doping of carbon materials on their potassium storage properties and facilitate their application in PIBs.
基金Financial supports by the National Natural Science Foundation of China (No. 21373269)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No. 10XNJ047)
文摘We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
