Amorphous carbon materials hold great potential for practical use in potassium-ion batteries(PIBs)due to their abundant resources,low cost and high structural stability.However,given the challenge of sluggish potassia...Amorphous carbon materials hold great potential for practical use in potassium-ion batteries(PIBs)due to their abundant resources,low cost and high structural stability.However,given the challenge of sluggish potassiation kinetics,the rate performance of amorphous carbon is severely hindered.Herein,amorphous carbon compounded with graphitic domains(HG-CNTs)was proposed as an advanced anode for PIBs.As directly verified by in situ transmission electron microscopy(TEM),the graphitic domains guarantee fast K-ions transport in the carbon composite at a high current density,while the amorphous carbon shells ensure the structural integrity during potassiation,thus boosting its fast and durable K^(+)storage.As a PlB anode,the HG-CNTs electrode exhibits not only a super-stable long-term cyclability(191.6 mAh g^(-1)at 1 A g^(-1)with almost no capacity decay over 3000 cycles),but also an outstanding rate performance(184.5 mAh g^(-1)at 2 A g^(-1)).Ex situ Raman and TEM results further suggest that the highly reversible structure of HG-CNTs is responsible for its superior electrochemical stability.This work provides helpful insights into the development of carbonaceous electrodes with both high rate capability and long cycle life for PIBs.展开更多
An interlayer is usually employed to tackle the interfacial instability issue between solid electrolytes(SEs)and Li metal caused by the side reaction.However,the failure mechanism of the ionic conductor interlayers,es...An interlayer is usually employed to tackle the interfacial instability issue between solid electrolytes(SEs)and Li metal caused by the side reaction.However,the failure mechanism of the ionic conductor interlayers,especially the influence from electron penetration,remains largely unknown.Herein,using Li1.3Al0.3Ti1.7(PO4)3(LATP)as the model SE and LiF as the interlayer,we use metal semiconductor contact barrier theory to reveal the failure origin of Li/LiF@LATP interface based on the calculation results of density functional theory(DFT),in which electrons can easily tunnel through the LiF grain boundary with F vacancies due to its narrow barrier width against electron injection,followed by the reduction of LATP.Remarkably,an Al-LiF bilayer between Li/LATP is found to dramatically promote the interfacial stability,due to the highly increased barrier width and homogenized electric field at the interface.Consequently,the Li symmetric cells with Al-LiF bilayer can exhibit excellent cyclability of more than 2,000 h superior to that interlayered by LiF monolayer(~860 h).Moreover,the Li/Al-LiF@LATP/LiFePO4 solid-state batteries deliver a capacity retention of 83.2%after 350 cycles at 0.5 C.Our findings emphasize the importance of tuning the electron transport behavior by optimizing the potential barrier for the interface design in high-performance solid-state batteries.展开更多
基金financially supported by the National Natural Science Foundation of China(52172240)the Fundamental Research Funds for the Central Universities(20720200075)the National Program for Thousand Young Talents of China,and the“Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University。
文摘Amorphous carbon materials hold great potential for practical use in potassium-ion batteries(PIBs)due to their abundant resources,low cost and high structural stability.However,given the challenge of sluggish potassiation kinetics,the rate performance of amorphous carbon is severely hindered.Herein,amorphous carbon compounded with graphitic domains(HG-CNTs)was proposed as an advanced anode for PIBs.As directly verified by in situ transmission electron microscopy(TEM),the graphitic domains guarantee fast K-ions transport in the carbon composite at a high current density,while the amorphous carbon shells ensure the structural integrity during potassiation,thus boosting its fast and durable K^(+)storage.As a PlB anode,the HG-CNTs electrode exhibits not only a super-stable long-term cyclability(191.6 mAh g^(-1)at 1 A g^(-1)with almost no capacity decay over 3000 cycles),but also an outstanding rate performance(184.5 mAh g^(-1)at 2 A g^(-1)).Ex situ Raman and TEM results further suggest that the highly reversible structure of HG-CNTs is responsible for its superior electrochemical stability.This work provides helpful insights into the development of carbonaceous electrodes with both high rate capability and long cycle life for PIBs.
基金This research was supported by the National Natural Science Foundation of China(Nos.52072323,52172240,and 11874307)Natural Science Foundation of Jiangxi Province(No.20192ACBL20048)+3 种基金Natural Science Foundation of Jiangsu Province(No.BK20200800)Scientific Research Project of Fujian Provincial Department of Education(No.JAT191150)the Fundamental Research Funds for the Central Universities(No.20720200075)the Double-First Class Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University.
文摘An interlayer is usually employed to tackle the interfacial instability issue between solid electrolytes(SEs)and Li metal caused by the side reaction.However,the failure mechanism of the ionic conductor interlayers,especially the influence from electron penetration,remains largely unknown.Herein,using Li1.3Al0.3Ti1.7(PO4)3(LATP)as the model SE and LiF as the interlayer,we use metal semiconductor contact barrier theory to reveal the failure origin of Li/LiF@LATP interface based on the calculation results of density functional theory(DFT),in which electrons can easily tunnel through the LiF grain boundary with F vacancies due to its narrow barrier width against electron injection,followed by the reduction of LATP.Remarkably,an Al-LiF bilayer between Li/LATP is found to dramatically promote the interfacial stability,due to the highly increased barrier width and homogenized electric field at the interface.Consequently,the Li symmetric cells with Al-LiF bilayer can exhibit excellent cyclability of more than 2,000 h superior to that interlayered by LiF monolayer(~860 h).Moreover,the Li/Al-LiF@LATP/LiFePO4 solid-state batteries deliver a capacity retention of 83.2%after 350 cycles at 0.5 C.Our findings emphasize the importance of tuning the electron transport behavior by optimizing the potential barrier for the interface design in high-performance solid-state batteries.