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
Strengthening in metals is traditionally achieved through the controlled creation of various grain boundaries(GBs),such as low-angle GBs,high-angle GBs,and twin boundaries(TBs).In the present study,a series of large-s...Strengthening in metals is traditionally achieved through the controlled creation of various grain boundaries(GBs),such as low-angle GBs,high-angle GBs,and twin boundaries(TBs).In the present study,a series of large-scale molecular dynamics simulations with spherical nanoindentation and carefully designed model were conducted to investigate and compare the strengthening effects of various GBs with nano-spacing as barriers of dislocation motion.Simulation results showed that high-angle twist GBs and TBs are similar barriers and low-angle twist GBs are less effective in obstructing dislocation motion.Corresponding atomistic mechanisms were also given.At a certain indentation depth,dislocation transmission and dislocation nucleation from the other side of boundaries were observed for low-angle twist GBs,whereas dislocations were completely blocked by high-angle twist GBs and TBs at the same indentation depth.The current findings should provide insights for comprehensive understanding of the strengthening effects of various GBs at nanoscale.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supported by the National Natural Science Foundation of China(Grant Nos.11472286,and 11672313)the National Key Basic Research Program of China(Grants Nos.2012CB932203,and 2012CB937500)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22040503)
文摘Strengthening in metals is traditionally achieved through the controlled creation of various grain boundaries(GBs),such as low-angle GBs,high-angle GBs,and twin boundaries(TBs).In the present study,a series of large-scale molecular dynamics simulations with spherical nanoindentation and carefully designed model were conducted to investigate and compare the strengthening effects of various GBs with nano-spacing as barriers of dislocation motion.Simulation results showed that high-angle twist GBs and TBs are similar barriers and low-angle twist GBs are less effective in obstructing dislocation motion.Corresponding atomistic mechanisms were also given.At a certain indentation depth,dislocation transmission and dislocation nucleation from the other side of boundaries were observed for low-angle twist GBs,whereas dislocations were completely blocked by high-angle twist GBs and TBs at the same indentation depth.The current findings should provide insights for comprehensive understanding of the strengthening effects of various GBs at nanoscale.
